SDMSDocID 2011400 •'.«/« IN THE UNITED STATES DISTRICT COURT FOR THE DISTRICT OF DELAWARE

UNITED STATES OF AMERICA, Plaintiff, v. Consolidated Civil Action Nos BP AMERICA, INC.., THE BUDD COMPANY, CHAMPLAIN CABLE CORPORATION, CHRYSLER CORPORATION, DAY INTERNATIONAL CORPORATION, E.I. DU PONT DE NEMOURS, 6 COMPANY, INC. GEC INDUSTRIES, INC., GENERAL MOTORS CORPORATION, HERCULES, INCORPORATED, ICI AMERICAS INC., MOTOR WHEEL CORPORATION, NEW CASTLE COUNTY, DELAWARE SCA SERVICES, INC., STANDARD CHLORINE OP DELAWARE, INC., STAUFPER CHEMICAL COMPANY, WASTE MANAGEMENT of DELAWARE, INC. WESTVACO CORPORATION, and WILMINGTON CHEMICAL CORPORATION, Dafandanta.

AND

flR000367 IN THE UNITED STATES DISTRICT COURT FOR THE DISTRICT OF DELAWARE

STATE OF DELAWARE, Plaintiff, v. Consolidated Civil Action Nos. BP AMERICA, INC. , ) THE BUDD COMPANY, ) CHAMPLAIN CABLE CORPORATION, ) CHRYSLER CORPORATION, ) DAY INTERNATIONAL CORPORATION, ) E.I. DU PONT DE NEMOURS, 6 ) COMPANY, INC. ) GEC INDUSTRIES, INC., ) GENERAL MOTORS CORPORATION, ) HERCULES, INCORPORATED, ) ICI AMERICAS INC., ) MOTOR WHEEL CORPORATION, ) NEW CASTLE COUNTY, DELAWARE ) SCA SERVICES, INC., ) STANDARD CHLORINE OP DELAWARE, ) INC. , STAUPPER CHEMICAL COMPANY, ) WASTE MANAGEMENT of DELAWARE, INC.,) WESTVACO CORPORATION, and ) WILMINGTON CHEMICAL CORPORATION, ) Dafendants. )

CONSENT DECREE

AR000368 IN THE UNITED STATES DISTRICT COURT — FOR THE DISTRICT OF DELAWARE L.CtC'.^

UNITED STATES OF AMERICA, ) ) Plaintiff, ) v. ) Consolidated ) Civil Action Noa BP AMERICA, INC.., ) THE BUDD COMPANY, ) CHAMPLAIN CABLE CORPORATION, ) CHRYSLER CORPORATION, ) DAY INTERNATIONAL CORPORATION, ) E.I. DU PONT DE NEMOURS, 6 ) COMPANY, INC. ) GEC INDUSTRIES, INC., ) GENERAL MOTORS CORPORATION, ) HERCULES, INCORPORATED, ) ICI AMERICAS INC., ) MOTOR WHEEL CORPORATION, ) NEW CASTLE COUNTY, DELAWARE ) SCA SERVICES, INC., ) STANDARD CHLORINE OP DELAWARE, ) INC., STAUPPEX CHEMICAL COMPANY, ) WASTE MANAGEMENT of DELAWARE, INC.,) WESTVACO CORPORATION, and ) WILMINGTON CHEMICAL CORPORATION, ) Defendants. )

AND

AR000369 IN THE UNITED STATES DISTRICT COURT FOR THE DISTRICT OF DELAWARE

STATS OF DELAWARE, Plaintiff, v. Conaolidated Civil Action Nos. 3P AMERICA, INC., THE BUDD COMPANY, CHAMPLAIN CABLE CORPORATION, CHRYSLER CORPORATION, DAY INTERNATIONAL CORPORATION, E.I. DU PONT 01 NEMOURS, 6 COMPANY, INC. GEC INDUSTRIES, INC., GENERAL MOTORS CORPORATION, HERCULES, INCORPORATED, ICZ AMERICAS INC., MOTOR WHEEL CORPORATION, NEW CASTLl COUNTY, DELAWARE SCA SERVICES, INC., STANDARD CHLORINE OP DELAWARE, INC., STAUPPUt CHEMICAL COMPANY, WESTVACWASTE MANAGEMENO CORPORATIONT of ,DELAWARE and , INC., WILMINGTON CHEMICAL CORPORATION, Defendant*.

CONSENT DICJtIB

AR000370 TABLE OF CONTENTS INTRODUCTION I. JURISDICTION 6 II. PARTIES BOUND 7 III. DEFINITIONS 3 IV. GENERAL PROVISIONS H V. TRUST FUND 15 VI. WORK TO BE PERFORMED 13 VII. IMPLEMENTATION OP WORK 24 VIII. U.S. EPA PERIODIC REVIEW 28 IX. REPORTING REQUIREMENTS .29 X. NOTICES 30 » XI. DESIGNATED REMEDIAL PROJECT MANAGER AND PROJECT COORDINATORS 32 XII. DATA QUALITY ASSURANCE 33 XIII. SITE ACCESS 33 XIV. SAMPLING AND DATA/DOCUMENT AVAILABILITY 42 XV. RECORD PRESERVATION 43 XVI. STIPULATED PENALTIES 44 XVII. FORCE MAJEURE 48 XVIII. DISPUTE RESOLUTION 51 XIX. RESPONSE AUTHORITY 53 XX. CONSISTENCY WITH NATIONAL CONTINGENCY PLAN 54 XXI. COVENANT NOT TO SUE 54

XXII. CLAIMS AGAINST THE PUHD AND PAYMENT OP RESPONSE COSTS AND NATURAL RESOURCE DAMAGES 60

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AR00037I XXIII. EFFECTIVE AND TERMINATION DATES SUBSEQUENT MODIFICATION

XXIV. USE OF DECREE/ADMISSIONS ...... 67

XXV. CONTRIBUTION PROTECTION ...... 53

XXVI . RETENTION OF JURISDICTION ...... 69

XXVII. OTHER PROVISIONS ...... 69 XXVIII . COMMUNITY RELATIONS ...... 71

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AR000372 IN THE UNITED STATES DISTRICT COURT FOR THE DISTRICT OF DELAWARE

UNITED STATES OF AMERICA, ) Plaintiff, )

v. ) Consolidated ) Civil Action Nos, ) and, BP AMERICA, INC. , a£ aJL. , )

Defendants, )

STATE OF DELAWARE, Plaintiff, v.

BP AMERICA, INC., ft£ Defendants. )

CONSENT DECREE INTROPOCTIQM A. Whereas, the United Statae of America ("United statae*), on behalf of the Administrator of the United States Environmental Protection Agency ('IPX'), filed this action pursuant to Sectione IOC and 107 of the Comprehensive Environmental Reeponee, Compeneation, and Liability Act of 1910, ae amended (*CERCLA»), 42 U.S.C. ff 9«0« and 9407; B. Whereas, the united Statae in its Complaint seefcs: (i) abatement of an imminent and substantial endenqerment to the

SR000373 public health, welfare, and the environaent; (ii) reimbursement of responaa costs incurred by EPA, together with accrued interest and costs of enforcement, for removal and remedial actions taken in response to the release or threat of release of hazardous substances from the Army Creek Landfill Superfund Site (the "Site*) located in New Castle County, Delaware; (iii) a declaratory judgment under Section 113(g)(2) of CERCLA, 42 u.s.c. ! 9«13(g)(2), and 2f U.S.C. S 2201, on liability for response costs or damages that will ba binding on any subsequent action or actions to recover further response costs or damages, and (iv) damages for injury to, destruction of, or lose of natural reaourcee under Section l07(a)(4)(C) of CZRCLA, 42 u.s.C. I f 9607(a)(4)(C); * c. Whereaa, the State of Delaware ('State') on behalf of the secretary of the Department of Natural Resources and Environmental Control (*DNREC*) filed an action pursuant to 7 Del. c. chapters 60, 63, and 90 for injunctive and other equitable relief to remedy a condition that may present an imminent and aubatantial hazard to the health of pereone or the environment and, pursuant to Section-107 of CHCXA, 42 U.s.C. I 9607, fort (i) reimbursement of reeponee coete incurred or to be incurreetay the Department (as hereinafter defined) in reeponee to a reissue) ot threat of release of hasardoua eubetancee from the Site, (ii) a declaratory judgment under Section 113(9) (2) of CZRCLA, 42 U.S.C. I 9413(9)(2), as to liability for further reeponee coeta, and (iii) damages for Injury to, destruction of,

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AR000371+ or loss of natural resources under Section 107(a)(4)(C) of CERCLA, 42 U.S.C. I 9607(a) (4) (C) ; D. Whereas, the United States and the State allege that hazardous substances as defined by Section 101(14) of CERCLA, 42 U.S.C. § 9601(14), and other pollutants or contaminants as defined by Section 101(33) of CERCLA, 42 U.S.C. § 9601(33), have been released and threaten to be released from the Site into the environment; E. whereas, for the purpose of entry and enforcement of this Consent Decree, the Settlors do not contest that the Complaint states a claim against the Settlors upon which relief may be granted. F. Whereas, the Settlors (as hereinafter defined) deny any * and all liability under any federal or state atatute, regulation, or common law for any reaponae coate incurred or to be incurred by the United statae, or the State caused by the relaaaa or threat of raleaae of hazardoua substances from the Site; G. Whereas, the United statae, the State, and the Settlors agree that Settlement of this matter and entry of this Consent Dacree are made in good faith in an effort to avoid expensive and protracted litigation; H. Whereas, all parties to thia Coneent Decree consent to the entry thereof; X. Whereaa, pursuant to Section 10S of CZJtCLA, 42 U.S.C. f 960S, EPA placed the Site on the National Priorities) Liat,

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AR000375 (*NPL*), sat forth at 40 c.F.R. Part 300, Appendix B, 43 Fed. Reg. 40666 (September a, 1983); J. Whereas, the Site has been divided by the EPA into tvo operable units, Operable Unit One and Operable Unit Two (hereinafter defined); K. whereaa, certain Settlors have participated in the funding and/or performance of the Remedial Inveatigation and Feasibility Study for Operable Unit one, pursuant to an Administrative Order on consent, consistent with CERCLA and the National Contingency Plan (»NCP*); L. whereas, EPA conducted the Remedial Investigation and Feasibility Study for operable Unit Two; M. whereaa, on September 30, I9t«, the United Statae % executed a Record of Decision ('HOD-1*), which ie attached hereto ae Exhibit 1, and which among other things requiree that certain health and environmental threats poeed by the Site be addreaaed by aaane of inetallation of a aurface cap, gee venting system, appropriate eroeion and sediment controls, and pumping of groundvater; N. Whereaa, on June 29, 1990, the United Statae executed a Record of Decision for Operable Unit Two (•HOD-2*) which ie attar-heel hereto as) Exhibit 2, and which, among other things, require*that certain health and environmental threata poeed by the Site be addreaaed by treating the groundvater extracted by the recovery veil network;

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&R000376 0. Whereas, various potentially responsible parties have been identified with regard to this Site and notified and revested to undertake the Remedial Action for Operable Unit one. various potentially responsible parties were also offered the opportunity to conduct the Remedial Investigation and Feasibility Study and the Remedial Action for operable Unit Two; p. Whereas, the Settlors have submitted to EPA a good faith offer to undertake and complete the Remedial Action for Operable Unit One and Operable Unit Two; Q. Whereas, in accordance with Section 121(f)(l)(F) of CERCLA, 42 U.S.C. S 9621(f)(1)(F), EPA notified the State prior to the negotiations with potentially reeponeible partiee t

regarding the scope of the remedial design and the remedial * action for the Site, and the State hae participated in theaa negotiations; R. whereas, in accordance with Section 122(j)(l) of CERCLA, 42 U.S.C. f 9622(j)(l), EPA hae notified federal natural rasourcae truataee in the Department of Commerce and in the Department of the Interior of the settlement negotiations and the federal trustaee have participated in theee negotiationes 3. Whereaa, subject to Section XXII (Claims Against the Fund anet Payment of Reeponee Coats), BP America, Inc.; The Sudd Compenyr Champ lain cable Corporation (formerly Raveg Industries, Inc.); Chrysler Corporation; Day International Corporation (formerly Electric Hose i Rubber Company); I.I. duPont da Nemours & Company, Inc.; QIC Industries, Inc. (formerly Gatae Engineering

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&R000377 Company, Inc.); General Motors Corporation; Hercules, Incorporated; Id Americas Inc.; Motor wheel Corporation; Mew Castle County, Delaware; SCA Services, Inc.; Standard Chlorine of Delaware, Inc.; stauffer Chemical Corporation; Waste Management of Delaware, Inc.; Westvaco Corporation; and Wilmington Chemical Corporation, have agreed to undertake and complete the Remedial Actions selected by the Records of Decision for Operable Unit One and Operable Unit Two and to reimburse EPA a portion of its past response costs; T. whereas, the Settlors have entered into an agreement which includea a plan for allocation of coate among themselves to fund the Remedial Actions for operable Unite One and Two; u. Whereas, the State hae agreed to withdraw a Notice of Conciliation issued to the County, and therefore, the State entara into this Consent Decree with the understanding that the county will undertake axpeditioue conetruction of the treatment plant called for in ROD-2. The partiee understand, subject to the timely entry of the Consent Decree, that *axpeditioue conetruction* means that the contract for conetruction will be awarded and the contractor will be ieaued a notice to proceed before December 31, 1990, and conetruction will be completed by June 30, 19*2. HO* TOMTOM, it ie hereby ordered, adjudged, and decreed ae follow*!

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AR000378 I. JURISDICTION A. This Court has jurisdiction over the subject natter cf these actions pursuant to 23 U.S.C. §§ 1331 and 1345, and 42 U.S.C. Si 9606, 9607, and 9613(b), and pendent jurisdiction over state law claims. The Court has personal jurisdiction over the Settlors, which, solely for the purposes of the Consent Decree and the underlying Complaints, waive all objectiona and defenses that they may have to the jurisdiction of the Court or to venue in this District. II. PAHTTgg MUMP A. This Consent Decree ehall apply to and be binding upon the Parties to this Consent Decree and their reepectiva succaaaors and assigns. Mo change in corporate or ownership • statue shall change the Settlors' raeponeibility to comply with the terms and conditions of thia Consent Decree. The undersigned representatives of the Settlors certify that they are fully authorized by the Party whom they rapraeent to enter into the terms and conditions of this Consent Decree, to execute this Consent Decree, and to legally bind such Party to thia Consent Decree. B. with regard to the Prime Contractors and any subcontractor, laboratory or consultant retained to perform the work required by thia Consent Decree, the Settlors shall, prior to such retention, provide them a copy of the portiona of this coneent Decree dealing with implementation of the remedial work and the standarde and requirements related thereto and ehall make

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AROG0379 compliance with those terns of this Consent Decree a condition of any contract for such Work. The portions of the consent Decree to be provided in compliance with this paragraph, shall be Sections IV (GENERAL PROVISIONS) ; VI (WORK TO BE PERFORMED) (only through Section 8(2)); VII ( IMPLEMENTATION OF WORK); IX (REPORTING REQUIREMENTS) ; XI (DESIGNATED REMEDIAL PROJECT MANAGER AND PROJECT COORDINATORS); XII (DATA QUALITY ASSURANCE) (only for contractors undertaking field sampling or laboratory analysis) ; XIV (SAMPLING AND DATA/ DOCUMENT AVAILABILITY) ; XV (RECORD PRESERVATION); and XVII (FORCE MAJZURE) .

III. A. Unless otherwise expressly provided herein, terme used in this consent Decree which are defined in COCLA or in , * ragulatione promulgated under C2XCLA shall have the meaning assigned to them in the statute or the regulatione. whenever terme listed below are ueed in thia Conaent Decree or in the Exhibita or Appendicee attached hereto or incorporated herein, the following definitione shall applyt 1. -CXHCLA* shall mean the Comprehensive Environmental Reeponee, Compensation, and Liability Act of 19tO, ae amended, 43 TJ.i.C. f 9601, *fi sjfcfl. 2* 'County* ehall mean Hew Caetle county, Delaware. 3» 'Day* ehall mean a calendar day unlaee expressly stated to b« a working day. ^forking day* shall mean a day other than a Saturday, Sunday, or federal holiday. Zn computing any period of time under thia Conaent Decree, where the) laat day

ARQG038G would fall on a Saturday, Sunday, or federal holiday, the shall run until the end of the next working day. 4. "DNREC* shall mean the Delaware Department of Natural Resources and Environmental Control. 5. *EPA* shall mean the United States Environmental Protection Agency. 6. 'National Contingency Plan* or *NCP* shall mean the National Contingency Plan promulgated pursuant to Section 105 of CERCLA, 42 U.S.C. § 9609, codified at 40 C.F.R. Part 300, including any amendments thereto. 7. 'Operation and Maintenance* or *0 4 M* shall mean those activitiee taken to maintain the effectiveness of the> . remedial measures implemented pursuant to thia Conaent Decree., o • & M shall not, include the pumping and treating of groundwater for a period of tan (10) years after commencement of operation of the treatment facility. 8. 'Operable Unit One* shall mean that aspect of the Site to be addreeaed by the remedy selected by ROD-1. Operable Unit One shall not mean that aspect of the Site to be addressed by the remedy selected for operable Unit Two. 9. 'Operable Unit Two* shall mean that aspect of the site to* me> addreeeed by the remedy selected by ROD-2. 10. * 'Overeight* shall mean all acts not inconeiatant with the NCP related to Work-l and Work-2 undertaken by 1PA, ita contractors, subcontractors, and/or agenta to assure and confirm performance by the Settlore of all the Settlors' dutiae and

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£R00038i obligations under and pursuant to this Consent Decree in the implementation of WorJc-1 and Wor)c-2. 11. "parties* shall mean the United States, the state and the Settlors. 12. 'Prime Contractor* shall mean the company or companies (including any substitute) selected by and retained on behalf of the Settlors in accordance with Section VI (WORK TO BE PERFORMED) of this Decree to undertake and complete the Work (as hereinafter defined). The Prime Contractor and any subcontractor retained by the Prime Contractor shall be deemed to be related by contract to each of the Settlors within the meaning of Section 107(b)(3) of CERCLA, 42 U.S.C. f 9607(b)(3). The Prime f Contractor and any subcontractor retained by the Prime Contractor shall be qualified to perform thoee portione of the Work for which they have been retained; provided, however, that the United States reserves the right to disapprove any such Prime Contractor in accordance with Section VI (WORK TO BE PERFORM!D) hereof. 13. 'Private settlors* shell mean all Settlora except for the County. 14. 'Record of Deeiaion-1* or *ROO-1* ehall mean the Record of Decision selecting remedial action for Operable Unit one signeat by the) Regional Administrator of IPA Region III on September 3O, 19M. 15. *Record of Decision-2* or *ROO-2* ehall eean the Record of Decision selecting remedial action for Operable Unit

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R000382 Two signed by the Regional Administrator of EPA Region in on June 29, 1990. 16. "Response Costs' shall mean all costs of response as "response* is defined by Section 1.01(25) of CERCLA, 42 U.S.C. § 9601(25), including the administrative, litigation and oversight costs, as well as the costs of preliminary assessments, site identifications, remedial investigations, and feasibility studies, incurred or to be incurred in response to releases or threatened releases of hazardous substancaa at or from the Site. 17. 'scope of work-l* or sow-l shall mean the description of Work-l as set forth in Exhibit 3 annexed hereto.

18. 'Scope of work-2* or sow-2 shall mean the f deacription of Work-2 as sat forth in Exhibit 4 annexed hereto. * 19. 'Settlors* shall aaan BP America, Inc.; The Budd \ ' Company; Champlain Cable Corporation; Chrysler Corporation, Day International Corporation, E.I. duPont de Nemours » Company, •^ Inc.; GEC Industries, Inc.; General Motors Corporation? Hercules, Incorporated; ICZ Americas, Inc.; Motor Wheel Corporation; New Castle County, Delaware; SCA Servicee, Inc.; standard Chlorine of Delaware, Inc.; Stauffar Chemical Company; Waete Management of Delaware Inc.; Weatvaco Corporation; and Wilmington Chemical corporation, and their reepective succaeeore and aeeigne. The provisions* of this Consent Decree set forth in Section XXI (COVENANT NOT TO SU1) and Section XXV (COMTltXOTXOIf PROTECTION) shall apply to Settlors whose acts or omission* gave riae to the alleged liability for CEHCLA and State lav claims pertaining to

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ARGGG383 the Site and those persons and entities whose acts or omissions gave rise to the alleged Liability of Settlors for CERCLA and State law claias pertaining to the Site, including with respect to both, those which were or are predecessors, successors, assigns, purchasers, sellers, affiliates, parents, subsidiaries, officers, directors, agents, and employees of Settlors and such persons and entities. 20. "Site* shall mean the 'facility* aa that term is defined in Section 101(9) of CERCLA, 42 U.S.C. i 9601(9), and 40 C.F.R. § 300.6, known as the Army Creek Landfill Superfund Site, conaisting of no leas than 60 acrae, located in New Caatle County, Delaware, approximately two milae aouthweet of New . caatle, Delaware, adjacent to Routee 13 and 40 to the weet and * Route 9 to the east. The Site includea the Property referred to under section XXII (SITE ACCESS) and the groundvater affected by the release of hazardoue aubetancee from the Army creek Landfill Superfund Site and/or the Delaware Sand and Gravel Landfill Superfund Site. i Site doee not include any aoile at the Delaware Sand and travel Landfill Superfund Site and any raaponsa action related thereto, or any other portion (other than groundvater) of the Delaware Sand and Gravel Landfill Superfund site. at. -'State* shall mean the State of Delaware, including the Department of Natural Reeourcea and Environmental Control (DMR1C).

- 12 - 22. 'Technical steering Committee* shall mean the entity, comprised of certain Settlors or their representatives, selected by the Settlors to perform certain functions regarding Worfc-1 and Worfc-2, which functions are defined in a separate agreement among the Settlors, within fifteen (15) days after the entry of this Consent Decree, the Settlors shall notify the United States of the identity of the members of the Technical steering Committee, and the Committee members' addresses and telephone numbers. Notwithstanding any delegation of duties to the Technical steering Committee, the Settlors shall not be relieved of the responsibility to assure full and proper performance of their obligations sat forth in thia Consent • Decree. » 23. ''Trust Fund* shall mean the fund into which, by contractual agreement, the Settlors have each agreed to pay the amount neceasary to pay for the implementation and completion of the Work to be performed under this Consent Decree. 24. TJnited statae' shall mean the United Statae of America, including all dapartmente, divieione, agencies, independent boarde and administratione of the federal government. 23. *Work* ehall mean all activitiee the Settlore are requires! to perform under this Consent Decree in implementing work-1 and Work-2. Work shall alao mean remedial action ae defined in CZRCLA 101(24), 42 U.S.C. § 9601(24). 26. lfork-1* shall constitute all taeka to implement the remedial action called for in ROD-1, excluding pumping of

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RGGG385 groundwater but including operation and maintenance, as acre specifically described in Scope of Worfc-1, the Work Plans, and any plans or schedules attached or to be attached thereto. For purposes of Section XXII, (CLAIMS AGAINST THE FUND AND PAYMENT CF RESPONSE COSTS), however, "Work-1* shall not include expenses related to the operation and maintenance of the remedial action set forth in ROD-1. 27. *Work-2* shall conatituta all taaka to implement the remedial action called for in ROD-2, aa well aa the pumping of groundwater called for in ROD-1 and including operation and maintenance, as more specifically daacrlbad in Scope of Work-2, the Work Plane, and any plane or echedulea attached or to be attached thereto. For purposes of Section XXII, (CLAIMS AGAINST THE FUND AND PAYMENT OP RESPONSE COSTS), however, Work-2 shall not include expeneee related to operation and maintenance of the remedial action aet forth in ROD-2. The partiee understand that for purposes of claime against the Fund, ten (10) years of pumping and treating after commencement of operation of the treatment facility ie coneidered remedial action and not operation and maintenance. 2S. *Work Plane* shall mean the document*, approved by EPA, whie* specifically describe the Work (including 04*) to be perform** by the) Settlors in order to fulfill the) United States' objective* through the implementation of the ramediae selected by ROD-l and ROD-2. There will be a separate Work Plan for Operable Unit one and Operable Unit Two. The Work Plan for Operable Unit

- 14 - One shall be consistent with the Scope of Work-l and once approved by EPA, shall be incorporated into this Consent Decree by reference as Exhibit 5. The Work Plan for Operable Unit Two shall be consistent with the Scope of Work-2 and once approved by EPA shall be incorporated into this Consent Decree by reference as Exhibit 6. IV. GENERAL PRQVISIOMS A. Objective* at the Parties, The objectives of the partiea in entering into this consent Decree are to protect public health and welfare and the environment from releasea or threatened releaaae of hazardous substances from the Site by the inveatigation, development, » deaign and implementation of the remedlea selected by ROD-l and ROD-2 and reimbursement of EPA's response coats. B. Obligations of Settlors; 1. Sattlore shall finance and perform the work in accordance with this Conaant Decree, including the SOW-l and sow- 2 and all standarde, apecificationa, and schedules set forth therein or developed thereunder, and in a manner coneiatant with the ROD-l and ROD-2. settlors shall alee reimburse the United Statae for Peat Reeponee Costs and Oversight Cost* ae provided in thia consent Decree. a. - The obligations of the Settlor* under thia consent Decree are joint and several. In the event of the ineolvency or other failure of any one or more of the Settlor* to implement the

- 15 - requirements of this Consent Decree, the remaining Settlors shall complete all such requirements.

C. Complia,pga With Applicable Law 1. All actiona taken by the Settlors pursuant to this Consent Decree shall be performed in accordance with the requirements of CERCLA and the national Contingency Plan. 0. Permits. 1. As provided in Section 121(a) of CERCLA and the KCP, no permit shall be required for any portion of the Work conducted entirely on the Site, where any portion of the Work requires a federal, state or local permit or approval under CERCLA and the NCP, the Settlor* shall timely submit applications and take all other actione necessary to obtain all such permit * approval*. 2. This Consent Decree ie not, and shall not be construed to be, a permit iseued pursuant to any federal or state statute or regulationa. V. TRPST FCTtP A. Prior to the execution of thie Concent Decree, the Settlore executed a Management Agreement eatabliahing the Truet Fund for Work-1. &V fattier* aha11 make payment* to the Truet Fund in accordance) vita the terme of their agreement. Such payment by each of the Settlors ie not a fine or penalty. c. In the event the coet of Work-1 exceeds the amount allocated for Work-1 and paid to the Truat Fund under thia Section V (TRUST FUND), the Technical Steering Committee shall provide timely written notice to the Settlors and EPA, and the Settlor* shall make additional payments to the Trust Fund in accordance with their agreement, to ensure the uninterrupted progress of the Work-1. 0. Any Settlor that fails to make payments required by this consent Decree shall become a 'Defaulting Defendant.* In the event that any of the Settlor* become* a Defaulting Defendant, the remaining Settlors shall make additional payments to the Trust Fund in an amount at leaat equal to the amount to be paid by the Defaulting Defendant(a) in accordance with their agreement, and ensure the uninterrupted progress of the Work. Nothing set forth herein ahall be construed to limit the right* * of other Settlor* to compel such Defaulting Defendant to satisfy its obligation* with respect to matters addressed in this Consent Decree. E. The purpose of this section V (TRUST FUND) is specifically to provide for and recognise the existence of a binding agreement among the settlore which ahall aaeure the necessary funding for activities undertaken by the Settlore pursuant to thia Consent Decree. The Partiee hereby expressly recognise) that the) Management Agreement la a separata and distinct/ document which ie binding only aa among the Settlore. P. No term* or conditiona in the Settlor*' Management Agreement shall be binding upon the United Statae or the State.

- 17 - G. Under the Management Agreement, defendants Chrysler Corporation, Day International Corporation, GEC Industries, Inc., General Motors corporation, standard Chlorine of Delaware, Inc., westvaco Corporation and Wilmington Chemical Corporation shall fully satisfy their obligations to the other Settlors relating to the Work and this Consent Decree by making a single premium payment to the Trust Fund, and shall not be involved in or reaponsibla to the other Settlors for actual implementation of the work. Nothing contained herein shall altar the term* and conditiona of the Management Agreement. H. Under the Management Agreement, defandante Herculee,

Incorporated, champlain Cable Corporation, Motor wheel p corporation and The Budd company shall not be involved in or , * responsible to the other Settlore for the actual implementation of the Work. Nothing contained herein shall alter the term* and condition* of the Management Agreement. I. Except for the Stipulated Penaltiea provisions set forth in Section XVT (STIPULATED PENALTIES), the obligation* imposed upon all Settlors under this Consent Decree shall be joint and several. VI. TOM TO W PPfgiMtP A~» SaAagfclati of Prime Contgeetarsj 1*. TBe> Settlors shall, within aixty (CO) calendar days of approval of the) respective work Plans, notify the United Statae of the name), title and qualifications of the Prime) Contractors for work-l and work-2. it is anticipated that there will be

- it - different Prime Contractors for Wor)c-L and worfc-2, and the following provisions shall apply separately to such Prime Contractors. The United States retains the right to disapprove the Prime Contractors initially proposed and any substitute Pri.r.e Contractors subsequently proposed if it determines that any such Prime Contractors are not qualified or are otherwise unable to perform those portions of the Work for which they have been retained, provided that the acceptance of the United States shall not be unreasonably withheld. The United Stataa shall notify the Settlors of its disapproval or acceptance of the Prime Contractor and the reason(s) therefor within fourteen calender days following receipt of such notice of the identity of the proposed Prime contractor. In the event of disapproval of the Prime • Contractor, the Settlor* shall notify the United States within forty-five (45) calendar day* of the receipt of notice of disapproval, of the name, title and qualifications of the Prime contractor who will replace the one who wae disapproved, or the Settlors, or any one or more of them may initiate Diapute Resolution pursuant to Section XVIII (DISPUTE RESOLUTION) hereof, if Dispute Reeolution ie invoked and EPA'a dec ieion to disapprove is sustained, Settlors shall name a subetitute Prime contractor within forty-five (45) daye of receipt of notice that EPA'a decision was sustained. The Settlors ahall within sixty («0) calendar days of acceptance of the Prime Contractor, enter into an agreement with that Prime Contractor to perform the work. Prior to execution of this Consent Decree, the county say submit

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A rt u o 0 o to EPA a list of contractors to be invited to bid as Prime Contractor for Work-2. In such event, the provisions of this Section VI(A)(l) (WORK TO BE PERFORMED) shall apply to EPA's acceptance process for any such Prime Contractor. 2. The United States and the State shall not be conaidered a party to any contract between or among the Settlors, Prime Contractors, and/or any subcontractors retained to perform the work. If, at any time during the pendency of this Decree, a decision is made to retain a substitute Prime Contractor, selection of the substitute shall be governed by the provisions of this Section.

a) within 60 calendar day* of the date on which anyf Prime Contractor ie accepted, the Settlore shall submit to EPA the namee of the subcontractors selected to perform any Work to be performed under such Prime Contractor. 3. EPA retain* the right to disapprove any subcontractors s «lacted to perform the Work, and any subcontractor selected to replace any such subcontractor* that EPA hae disapproved, if it reasonably determines that any such subcontractor ia not qualified or otherwise unable to perform those portions of the work for which it has been retained, provided that the acceptance of EPA smttll not be unreaeonably withheld. The EPA ahall notify the Settlors of its disapproval of any subcontractor and the reaaon(s) therefor within fourteen days following receipt of notice of such subcontractor, or such subcontractor ahall be deemed accepted, within forty-five calendar days of the receipt

- 20 - of any notice of disapproval, Settlors shall notify the United State* of the name and qualifications of a replacement subcontractor, or Settlors, or one or more of them, may initiate Dispute Resolution pursuant to Section XVIII (DISPUTE RESOLUTION) hereof. If Dispute Resolution is invoked and EPA's decision to disapprove is sustained, Settlors shall name a replacement subcontractor within forty-five daya of receipt of notice that EPA's decision was sustained. 4. Paul c. Rizzo and Associates is accepted aa Private Settlors' engineering firm and construction aanagar. Roy F. Weston, Inc. is accepted as the County's engineering firm and construction manager. Their profeaaional subcontractor*, such.as surveyors, drillers, and electrician* ahall not require separate review. \ 3. Insurance 1. The Settlors shall require each of the Prime contractors to purchaae and maintain in force insurance policies to fully protect the United Statae and the public againat liability arising out of the act* or omiseione of Prime Contractors and any subcontractor, agent, or employee retained to perform the Work* For each prime contractor, said policia* ahall provide) coverage in amount* not less than those specified below: a. workmen's compensation and Employer's Liability Insurance in accordance with the lavs of the State of Delaware;

- 21 - b. comprehensive General Liability Insurance, including; (1) Bodily Injury Liability $1,000,000 each person $1,000,000 each occurrence (2) Property Damage Liability 91,000,000 each accident $1,000,000 aggregate c. Automobile Liability Insurance; (1) Bodily Injury Liability $500,000 each peraon $1,000,000 each i accident (2) Property Damage Liability $900,000 each accident d. Umbrella Policy in the amount of $2,000,000 which shall provide coverage in axcee* of the underlying coverage daacribed above. 2. Ten (10) day* prior to the commencement of the work, the Settlors, through the Prime Contractors, ehall provide the United States vita copies of all policies of insurance. 3. In the event the Prime contractors are unable to obtain smcb insurance after uaing beet effort* the Settlors shall give EPA written notice delineating the) best efforts made by the Prims contractors. Such failure to obtain or maintain any insurance required by this Section ahall not be a violation of this consent Decree if Settlors demonetrata to EPA'* satisfaction - 22 -

<-> c\ that good faith efforts were made to obtain such insurance and that such insurance is not available at reasonable cost. 4. The Settlors shall indemnify the United States ar.d hold the United States harmless for any claim arising from any injuries or damages to persons or property resulting from any acts or omissions of the Settlors, their contractors, subcontractors, or any person acting on their behalf in carrying out any activities pursuant to the term* of this Consent Decree. The foregoing shall not include any officer, employee, agent, contractor, subcontractor or any other person acting on behalf of the United statea or any agency or department thereof. Nothing in this Section is intended in any way to expand or incraaae any liability of the United Statae, ite agente or amployaae, under, existing law or to altar or affect any rule of law that would govern the liability of the United Statae in the absence of this Consent Decree. C. Performance Standard* 1. The Work performed by Settlors under this Concent Decree for operable Unit One shall achieve the performance standard* selected in ROD-l, attached hereto and incorporated herein as Exhibit 1, as set forth in SOW-l, attached hereto and incorporated herein ae Exhibit 3. The work performed by settlor* under tfti* Consent Decree for Operable Unit Two ahall achieve the performance standards selected in ROD-2, attached hereto and incorporated herein as Exhibit 2, as set forth in SOW-2, attached hereto and incorporated herein as Exhibit 4. The) performance

- 23 -

R G C 0 3 ^ b standards selected by ROD-l and ROD-2 shall be incorporated into, the appropriate work Plans. 2. settlors acknowledge and agree that nothing in this Consent Decree or in the Work Plans constitutes a warranty or representation of any Kind by the United States that compliance with this Consent Oacrea will achieve the Performance Standards set forth in ROD-l and ROD-2 and in Section vi(C)(l) (WORK TO BE PERFORMED), above, and that compliance with the Consent Decree shall not foreclose the United Statea from seeking achievement of the applicable Performance Standards. 3. In the event that EPA or the Settlor* determine(*) that additional response activities are neceeeary to meet the . Performance Standarda described in paragraph 1, notification of * such additional response activitiee shall be provided to EPA's Remedial Project Manager or to Settlors' Project Coordinators. 4. Any additional reeponee activitiae that the Settlor* determine are necessary to meet Performance Standard* shall be subject to approval by EPA, after reasonable opportunity for reviev and comment by the State, and shall be completed by the Settlors in accordance with plans, specifications and schedules approved by EPA pursuant to Section VIZ (IMPLEMENTATION OF WOPX|> 5. Unless otherwise stated by EPA to be a larger period, within thirty (30) days of receipt of notice from EPA that additional response activitiae are necessary to meet the Performance Standards, the Settlors ehall submit for approval by

- 24 - EPA, after reasonable opportunity Cor review and comment by the State, a work plan for additional response activities. Upon approval of the plan pursuant to Section VII (IMPLEMENTATION OF WORK), the Settlors shall implement the plan for additional response activities in accordance with the schedule contained therein. This subsection does not apply to additiona. response actions required by Section XXI(F) (COVENANT NOT TO SUE). VII. TUPLEyfENTATIOM OF WORK A. Within thirty (30) daya after notification from EPA of the lodging of this Consent Decree with the Court, the Settlors shall submit their preliminary draft Work Plane to EPA and the state. The Settlora shall revise their Work Plan* conaistent . with SOW-1 and SOW-2, in accordance with any comments made by EPA * and the State., within thirty (30) daye after the Settlor* receive notice that this Consent Decree hae been entered by the court, the Settlor* shall submit their final Work Plane to EPA and the State. The Work Plane ahall provide for deeign of the remedy sat forth in ROD-l and ROD-2, in accordance with SOW-1 and SOW-2. A Health and Safety Plan for field deeign activitiae shall be prepared in conformance with applicable Occupational safety and Health Administration and EPA requirement*, and incorporated into the Work Plane. EPA ahall review the work Pan* for consistency with ROD-l and ROO-2, in accordance with sow-i and SOW-2, and notify the Settlore in writing of EPA'a approval or disapproval of the Work Plans. In the event of EPA'* disapproval, EPA shall specify the deficiency(ies) of each work

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<-, - 7 0 J I Plan, if any, in writing. Within fourteen (14) days of the receipt of such notice of disapproval, Settlors shall submit revised Work Plans which correct such deficiencies. The Settlors may, if they wish, submit further information to EPA during the fourteen (14) day period giving reasons why the original Work Plans should be approved; however, such submission shall not change the obligation of the Settlors to submit revised Work Plans within the fourteen (14) day period should EPA not reverse its decision, subsequent EPA disapprovals shall be subject to the terms of Section XVIII (DISPUTE RESOLUTION) of this Consent Decree. B. Upon approval by EPA, the Settlor*' Work Plan* stiall.be incorporated into this Consent Decree. The term* and schedule* in the Work Plans shall become requirements of this Consent Decree. C. Subject to Section XXII (SITE ACCESS) of thia Consent Decree, the Settlor* shall commence the Work no later than ninety (90) day* from the date of receipt of EPA's acceptance of the Prime Contractor* to perform the work under each work Plan. The work shall be completed in accordance with the standard*, specifications, and the schedule of completion set forth in the EPA-approved Work Plans. Failure to comply vita any provision of the schedolee and milestone* in the Work Plans shall subject the Settlors to the imposition of stipulated penalties as set forth in Section XVT (STIPULATED PENALTIES) of this Consent Decree.

- 2« - D. The Parties agree that the Work and any schedule of completion may be modified by written agreement of the Parties hereto which agreement shall be filed with the Court, except that the EPA Remedial Project Manager may make minor modifications which may affect interim, but not final, deadlines for work to be performed under this Decree. However, minor modifications are those changes which do not materially alter the requirements of this Consent Decree. No informal advice, guidance, suggestions, or comments, including, but not limited to, oral representations, made by EPA or the State regarding reports, plans, specifications, schedule*, or any other writing

submitted by the Settlor* shall be construed ae relieving the p Settlor* of their obligation to obtain such formal approval a* • • may be required by thi* Conaant Decree. E. The Settlor* ahall maintain documentation, conaistent with the NCP, 40 C.F.R. } 300.69, or any amendments thereto, to support all actione taken in performing the Work. The Settlor* shall provide written prograae report* to the EPA Remedial Project Manager ae required by thie Consent Decree and the Work Plan*, containing the information therein required. P. If a progra** or monitoring report, ae required by SectioavXX(A) (REPORTINO REQUIREMENTS), submitted to EPA i* deficient, EPA ahall notify the appropriate Project Coordinator within ninety (90) days of receipt of auch prograae or monitoring report by EPA. The notice ahall include a deecription of the deficiencies. Within fourteen (14) days of receipt by the

- 27 - Settlors of a notice of deficiency in a progress or monitoring report, the Settlors shall sake the necessary changes and resubmit the progress or monitoring report to the EPA Remedial Project Manager. The Settlors may, if they wish, submit further information to EPA during the fourteen (14) day period giving reasons why the original progress or monitoring report should be approved; however, such a submission shall not change the obligation of the Settlors to resubmit the progress or monitoring report within the fourteen (14) day period should EPA not reverse its decision. a. The Settlors shall notify the United Statae orally and in writing within two working daye of the completion of all of. the element* set forth in each Work Plan. The United State* k shall review the Work and indicate its agreement or disagreement as to the satisfactory completion of the Work within a reasonable time of (1) receipt of such notice or (2) receipt of all sampling data required to be submitted to EPA under the Work Plane, whichever ie later. H. If the United State* believee that Work-1 and/or work-2 hae not been *ati*factorily completed in accordance with the Work Plans, it shall notify the Settlors, in writing, of what muat be done t9 complete the Work, referencing the- specific portion(a) of the work> Plane and propoaing a schedule of completion. Thereafter, the) Settlors ahall either (1) undertake and complete such aeasuree in accordance with the proposed schedule of completion, or, if the Settlors object to such proposed measures, (2) within five working days of receipt of the United States' notification, initiate the dispute resolution procedures of Section XVIII (DISPUTE RESOLUTION) of this Consent Decree. I. In the event the United States determines, at any time, that there have been violations of the terms of this Consent Decree and the United States has previously notified the Settlors or the appropriate Project Coordinator in writing of such violations, and the Settlors have failed to remedy such noncompliance with the term* of thi* Consent Decree, then the United States, may perform such portion* of the Work a* EPA determine* it wishes to undertake and seek to recover the coats thereof from the Settlors. The United Statae shall give the » Settlors at least fourteen day* written notice of it* intent to * undertake the, Work. The United Statae' right to perform portions of the Work under this paragraph i* In addition to and not in limitation of the United Statae' right to take any other action under law, including, but not limited to, enforcing the term* of thi* Concent Decree. Further, the provision* of thi* Conaent Decree ahall not limit EPA in any way in taking action at the Site in the event of an imminent and substantial endangerment to the public heelth or welfare or the environment. vxix. g.a. EPA patiopie Rivim A. At-least every five years after initiation of the remedial action (Work) at the Site, EPA ehall review the remedial action ae required by Section 121(c) of CERCLA, 42 U.S.C. f 962l(c). The Settlors ahall in connection with such review* make - at -

A t\ C C u k u i available the studies and investigations in their possession as ill as such analysis thereof, as determined necessary by EPA. B. The Settlors shall be provided with an opportunity to confer with EPA on any additional response action proposed by EPA as a result of the 5-year review process and to submit written comments for the record during the public comment period. After the period for submission of written commanta is closed, the Regional Administrator, EPA Region III, shall determine in writing whether further reaponae action is appropriate. If the Regional Administrator, EPA Region III, determinea that the remedial action is not protective of human health and the environment, based upon Information received, in whole or in j part, during the review conducted pursuant to Section 121(c) of CERCLA, 42 U.S-.C. f 9«21(c), the Settlors shall, subject to Section XXI(F) (COVENANT NOT TO SUE) of thia Consent Decree, undertake the reaponae actlone that EPA hae determined are appropriate. IX. MPOttTIMO MQUIRgMBPM A. The Private settlors and the County shall each submit to EPA and the State written monthly progreee reporta regarding Work-l and Work-2, respectively, whicht (a) deecribe the actions which hs*e> been taken toward achieving compliance with thia conaant Deeraa during the previous month; (b) include all sampling and teats and all other data, including all raw data, generated by the Settlors or their contractors or agents in the previous month; (c) include all plans and procedures completed

- 30 - under the Work Plans during the previous month; (d) describe all actions, including data collection and implementation of plans which are scheduled for the next month and provide other information relating to the progress of construction; (e) include information regarding percentage of completion, unresolved delays encountered or anticipated that may affect the future schedule for implementation of the Work or Work Plane, and a deecription of efforts made to mitigate those delaya or anticipated delays. The Settlors shall submit theaa progreaa reporta to EPA and the state by the tenth day of every month following the entry of this Consent Decree. B. with respect to the discharge of recovered groundwater from the County's treatment facility the County shall submit to the State discharge monitoring reporta (DMRe) in accordance with the requirement* set forth in SOW-2. C. Upon the occurrence of any event during performance of the work which, pursuant to section 103 of CERCLA, 42 U.S.C. i 9603, require* reporting to the National Reeponee Center, settlore shall promptly orally notify the EPA Remedial Project Manager or in the event of the unavailability of the Remedial Project Manager, the Emergency Reeponee Section, Region III, united States Environmental Protection Agency, in addition to the reportinsj required by Section 103. within twenty (20) days of the onset of auch an event, Settlors ehall furnish to the United statee a written report, signed by the appropriate Project coordinator, setting forth the event* which occurred and the

- 31 - measures taken, and to be taken, in response thereto, within thirty (30) days of the conclusion of such an event, the Settlors shall submit a report setting forth all actions taken to respond thereto. X. MOTICES whenever under the term* of thi* Conaent Decree notice is required to be given or a report or other document ia required to be forwarded by one Party to another, it shall be directed, in writing, to the following individuals at the addressee specified below (or to such other address a* such Party may, from time to time, designate by written notice)t 1. If to the United Statae or EPA: j a. Remedial Project Manager Army creek Landfill Site U.S; EPA Region 3 s 941 Cheetnut Building Philadelphia, PA 19107 b. Assistant Regional Counsel Army Creek Landfill Site Office of Regional Counsel 841 Cheetnut Building Philadelphia, PA 1910? c. Chief, Environmental Enforcement Section U.S. Department of Juetice P. O. Box 7611 sen Franklin station Washington, O.C. 20044 DOJ Ref. NO. 90-11-2-411 3. Xf to the) States a. Robert M. Allen Department of Natural Resources and Environmental Control 7 IS Grantham Lane) New Castls, 01 19730

A i\ u 0 b. Jeanne L. Langdon Deputy Attorney General State of Delaware Department of Natural Resources and Environmental Control 39 Kings Highway Dover, DE 19903 c. Water Pollution Control Branch State of Delaware Department of Natural Resources and Environmental Control Division of Water Resources P.O. Box 1401 Dover, DE 19903 3. If to the Settlors: a. F. Michael Parkowski, Esquire 116 west Water Street Post Office Box 59* Dover, DE 19903 b. New Castle County Attorney t County Department of Lav city-County Building • 300 French Street, 8th Floor Wilmington, Dl 19101 XI. DESIGNATED REMEDIAL PROJECT MANAGER AND PROJECT COORDINATORS A. The United State* ha* selected or will select a Remedial Project Manager for this Site whoee bueine** address is listed in Section X (NOTICES) of this Decree, within ten (10) daye after the entry of this Coneent Decree, the Settlors shall notify the) EPA Remedial Project Manager, in writing, of the name, addreee)*, ajst telephone number of their Project Coordinator*. EPA and thsrtsttlors ehall have the right to change- their reepective Remedial Project Manager and Project Coordinators. Such a change shall be accomplished by notifying the other Parties in writing at least five (5) days prior to the change. It is anticipated

- 33 - that the Private Settlors will have a Project Coordinator for Work-1 and that the County will have a Project Coordinator far work-2. 3. The EPA Remedial Project Manager and his designated representatives shall have the authority lawfully vested in the Remedial Project Manager and the On-Scene Coordinator by the applicable provisions of the NCP, 40 C.F.R. Part 300. c. The EPA Remedial Project Manager has the right to suspend the Work if the Work i* not being performed in accordance with this consent Decree or if the Work cauaes or threatana to causa a release or threatened releaae of hazardous substance* which may create an imminent and substantial endangerment to human health and the environment. If the Work i* suspended, • Settlor* may file an emergency petition for expedited Dispute Raaolution. If the EPA Remedial Project Manager suspend* any Work and the raaeons are due to the act* or omission* of the Settlors or act* or omission* of the Prime Contractor* or subcontractor*, then any extension of the schedule of completion shall be at EPA'* discretion, exercised in good faith. D. Minor modifications in the studies, techniguee, procedures, designs or interim deadlines utilised in carrying out this Consent Decree, and necessary to the completion of Work-1 or work-3 mmy be mads by mutual agreement of the EPA Remedial Project Manager, and either the county's or the Private Settlor*' Project coordinator, as appropriate. Such modifications shall be mad* by exchange of letters agreeing to auch changes and ahall

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A r\ u u U w u b have as an effective date the date on which the letter from EPA' 3 Remedial Project Manager is signed. The absence of the EPA Remedial Project Manager or his representatives from the site shall not be cause for the stoppage of Work. XII. DATA QUALITY ASSURANCg A. The Private Settlors and the County shall use Quality Assurance/Quality Control practices and procedures, including chain-of -custody procedures, in accordance with guidance provided in *EPA NEIC Policies and Procaduree Manual* dated May 1978, revised November 1984, EPA 330/9-78-001-R and 'Interim Guidelines and Specifications for Preparing Quality Assurance Project Plan*,* December 1980, QAMS-003/80, while conducting all sample collection and analysis activitiee required by this Conaent • Decree: The Private Settlor* and the County shall consult with the EPA Remedial Project Manager in planning for, and prior to, all sampling and analyaia required by the Work Plane, and subsequent EPA-approvad plane prepared ae pert of this Consent Decree. In order to provide adequate Quality A**urance and Quality control regarding all eample* collected and analyzed pursuant to this Consent Decree, the. Private Settlors and the county ahall » 1. Uee only labor at or iee which have a documented Quality Assurance Program that compliee with EPA guidance document QAHS-OOS/tOi 2. Ensure that United States personnel and/or United states authorized representatives are allowed reasonable access

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A r( u o u 4 u / to laboratories, records, and personne- utilized by the ?rivi-_e Settlors and the County for analysis of samples collected pursuant to this Consent Decree; 3. submit a Quality Assurance and Quality Control Plan (*QA/QC Plan*) for the collection, transportation, analysis and reporting to be conducted, as appropriate, during the Work undertaken pursuant to this Consent Decree. The QA/QC Plan shall be submitted to the EPA Remedial Project Manager for review and approval in accordance with the schedule to be included in worfc-i and Work-2 and prior to initiating any respective field investigation* to be described in the raapective QA/QC Plan. EPA shall review the QA/QC Plan and notify the Settlor* in writing, of EPA's approval or diaapproval of the QA/QC Plan, within fourteen (14) day* of receipt of any notice of disapproval, the Private Settlor* and/or the County (ae appropriate) shall submit a revised QA/QC Plan which addraaaae auch deficienciee. Each plan shall specify, for the phaae of activity addreeeed, the data quality objective*, the number, time and location of soil, air, surface water and groundvater samples to be taken, sample collection and transportation procedures, data analysis method*, and validation and reporting procedures that are consistent with the ROOV 1PA NIXC Policies and Procedures Manual, QAKS-005/tO, and appropriate EPA guidance; 4. Ensurs, except where otherwise specified in subsequent EPA-approved plans prepared as part of this Decree, that the lax. ratory(ies) analysing sample* required by this Consent Decree shall use the methods and submit deliverables delineated in the current 'Statement of Work of the EPA Contract Lab Program* (»CLP*). Analysis for all constituents and physical parameters in which CLP methods will not be used shall be described in detail in the appropriate QA/QC Plan and approved by the EPA Remedial Project Manager prior to all sampling and analysis; 5. Ensure that any laboratory analyzing samples pursuant to this Consent Decree demonstrate ita capability to perform analysis throughout Work in compliance with CLP requirements through the periodic analysis of Performance Evaluation (*PE*) samples. EPA may waive thia requirement to analyze PE samples provided the laboratory periodically analyxea PI samplea submitted by EPA or a state agency and documentation of periodic PE sample analysis i* submitted to the EPA Remedial Project Manager for verification in accordance with the schedule to be included in the Work Plan; 6. Conduct an appropriate number of field audits, to be described in the QA/QC Plan, during Work to verify that sampling is being performed according to the QA/QC Plan. The Private settlor* and the County shall submit a report to the EPA Remedial Project Manager within fifteen (IS) days of completion of each t audit. 1me> Private Settlors and the County agree to report deficiencies in implementation of the QA/QC Plan and propose corrective actions within twenty-four hours of the time the any of the Settlors or any contractor or subcontractor discover any

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A rt u u U k U :, deficiency. The Settlors agree to take immediate action to correct any deficiency. 7. Conduct, in accordance with the QA/QC Plan, an appropriate number of audits of the laboratories that will analyze samples from the Site at a frequency to be specified in the respective Work Plans during the time the laboratories are conducting analyses. The audits shall be conducted to verify analytical capability. Audit reports shall be submitted to the EPA Remedial Project Manager within fifteen (13) daya of completion of each audit. The Private Settlors and the County agree to report deficiencies within twenty-four hours of the tiaa that any of the Settlor* discover the deficiency. The Private Settlor* and the county agree to make their beet efforts to take • corrective action* immediately. Laboratoriae which are CLP lab« need not be audited if the CLP proceduree are employed by the Private Settlor* and the County; 8. Provide data validation of analyse* performed by the laboratory(iee) in accordance with the 'Functional Guideline* for Data Review* for data derived by CLP methode, or if another method is used, the data validation shall be performed in accordance) with the) QA/QC data validation criteria eet forth in that metbe*}. for methods lacking QA/QC data validation protocols* the) Private Settlors and the County must establiah validation criteria such as those in Section • of the) SPA Seriee Methods in 40 C.P.R. Part 13«. The Private Settlors and the county agree to submit the appropriate quality aasurance data

- 3t - validation summary reports, along with sample data and summary sheet*, to the EPA Remedial Project Manager in accordance with reporting requirements to be described in the Work Plans. XIII. SITE A. The County, which owns or controls access to certain portions of the properties constituting the Army Creek Landfill Site (such areas referred to hereinafter as the "Property") , is hereby ordered and hereby agrees: 1. To permit the United States, it* repreaentatives or its contractors, the State, its repreeentativea or ita contractor*, the Private Settlor*, the Technical steering Committee, Prime Contractors, subcontractor* and their reapecfeive representatives to enter upon the Property for the purpose of . * effectuating all term* of thi* Concent Decree; 2. Not to interfere with or disturb the Work to be performed under thi* Concent Decree by the Private Settlor* or altar the remedial facilitiae conetructad by the Private Settlors pursuant to thi* Consent Decree; 3. Not to convey any title, easement, or other interest in the Property or any portion thereof, unleea such conveyance includes a covenant that! (i) permits the United state*, ita repreeentativee or its contractors, the State, ite representatives or its contractors, Private Settlors, the Technical Steering Committee, Prime contractors, subcontractor* and their respective representatives to enter upon the Property or portions thereof conveyed, for purposes of effectuating all

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rt u u 0 U i i terms of this Consent Decree; (ii) contains a binding agreement not to interfere with or disturb the work and any future respor,s« activities (including 0 4 M) that may be performed; and (iii) contains a binding agreement to inform any person or entity that subsequently acquires any title, easement, or other interest in the Property or any portions thereof of the requirements, conditions, and operative effect of thia Section XIII (SITE ACCESS). 3. At leaat ninety (90) days prior to any conveyance that is subject to this Section, the County shall notify, by regiatered mail, the United Statae, the State and the other Settlor* of the intent to convey any title, eaaement, or other interest in the Property , or any portion thereof, and of the propoaad wording of the covenant required under thie Section x'lli \ (SITE ACCESS). The notice shall include the name, addresa and telephone number of the traneferee. The reetrictions and obligatione set forth in thie Section XIII (SITE ACCESS) shall be made to run with the land and ahall be binding upon any and all person* or entitiee that acquire any title, eaaement, or other interest in the Property or any portion thereof. c. The Private Settlors ars hereby ordered and hereby / agrees I. Hot to interfere with or disturb the) work to be » performed! under this Consent Decree by the) County or alter the remedial facilities constructed by the) County pursuant to this Consent Decree.

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A R u u U U i i. 2. within thirty days after entry of this Consent Decree, the Private Settlors and the County shall meet and develop a plan for their coordinated implementation of all construction and operation and maintenance activitiea associated with their respective undertaking of Work 1 or Work 2. The plan shall be framed to permit the most cost-effective implementation of both Work 1 and Work 2 consistent with the schedules for such work set forth in this Consent Decree. The plan shall not alter any of the requirements imposed under this Consent Decree. 3. Representatives of the Private Settlors and the county shall at regular interval* review this plan and make such adjustmenta aa may be necessary to achieve the above-etated purpoaa of thi* plan. D. In t£e event ace*** ie needed to property not owned or controlled by the County and such owner refuaee accea*, the Settlor* shall u*e their be*t effort* to secure voluntary access. In the event that the Settlor* are unable, deepite beet efforts, to obtain auch acceee at raaaonable coet within thirty (30) day*, they ahall notify the EPA, in writing, of their failure to obtain such acceee, and the effort* made to obtain such acceee. If the Settlors have used their beet efforts and failed to obtain access, sjmt the Settlors satiety the requirements of Section XVTI (FORCE MVBCntB), failure to obtain access shall be considered a fore* ma/lauM event. The Settlors shall bear all reasonable and necessary coats and expenses to obtain such access (including all costs or expenses incurred by the United States in exereieing any

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AriuuU4 i J legal authority it may have to assist the Settlors in obtaining such access; which costs shall be considered oversight costs under Section XXII (CLAIMS AGAINST THE FUND AND PAYMENT OF RESPONSE COSTS) of this Consent Decree), ex.ept to the extent that the Court may order such costs to be paid by a person or entity other than the United statea. E. The State and the County shall cooperate to assure that the property owned or controlled by the County shall not be used in a manner inconsistent with the remedial action for Operable Units One and Two, including any wetland* or other natural reaourca restoration and/or preservation project required by the State of Delaware, the United Statae Department of the Interior, and/or the United Statae Department of Commerce, ae a reeult of * subsequent proceeding* or settlement agreements. F. The Settlors ahall not prevent the Federal and/or state governmenta, or their deelgnated represent*tivee, from gaining acceaa to the Site. G. Nothing in thie Section XZZZ (SITE ACCESS) ahall limit the authority of the United States or state to enter the site under faderel or state- lav. H. Any disputes concerning this Sits Acceee provision shall bat resolved via the dispute resolution procedure establish* by Section XVZZZ (OZSPUTI RHOLDTIOW) herein. In the event of any dispute between the Privets Settlors and the County concerning this Sits Access provision, either the) Private Settlors or the county may file a petition under Section XVIZZ(A)

- 42 - (DISPUTE RESOLUTION) if the parties cannot resolve within five working days any such dispute. XIV. SAMPLING AND DATA/DOCUMENT AVAILABILITY A. The Settlors shall promptly make available to the United States the results of all sampling and/or tests or other data, including raw data, generated by the Settlors, or on their behalf, pursuant to this Consent Decree. The Settlors shall submit these results in reports as described in Section IX (REPORTING REQUIREMENTS) of this Consent Decree, and as described in the Work Plans. EPA promptly will make available to the Settlors the validated reaults of sampling and/or teats or other validated data similarly generated by EPA. B. At the request of EPA, the Sattlore ahall allow split * or duplicates aamplea to be taken by the United Statae and/or its authorized representativae of any samples collected by the Settlors pursuant to the implementation of thie Conaent Decree. The Settlor* shall notify EPA aaven (?) daye in advance of any sampling activity. c. The Settlore may a**ert a claim of buaine** confidentiality covering part of the information or documentation developed in connection with thie consent Decree in the manner deecribed in 40 C.F.R. } 2.203(b). Such claims shall be supportem) by documentation when the assertion ie made by the settlors in accordance with the requirements of 40 C.P.R. f 2.204(e)(4). Analytical data and other information specified in Section 104(o) of CZRCZA, 42 U.S.C. I 104(a), ehall not be

- 43 -

U 4 , J claimed as confidential by the Settlors. Information determined to be confidential by EPA will be made available to the public only in accordance with the procedures set forth in 40 C.F.R. Part 2, Subpart B. If no claim of business confidentiality accompanies the information when it is submitted to EPA, it may be made available to the public by EPA without further notice to the Settlors. XV. RECOUP PRgag*VXTTQM A. For ten (10) year* after termination of this Consent Decree, Private Settlors and the County, or reaponsible persons designated by them, ahall retain all record* and document*, including all coat documentation, in their possession or in the possaaaion of their divisions, employees, agenta, accountant*, * contractor*, or attorneye which relate reepectively in any way to work-l and Work-2, deepite any document retention policy to the contrary. Notwithstanding any delegation of cuatody of such documents, Private Settlor* and the County shall be reaponsible for any respective failure to preeerve. At the end of thie tan (10) year period, the Private Settlors and the County, or their agent(s) having custody of the documents, shall notify EPA at least sixty (60) days prior to the destruction of any such document** If, however, Settlors submit claims against the Fund pursuant*, to Section XXII (CLAIMS AGAINST THI FUVD AMD PAYMfMT OF RJESPONS* COST*), then all cost documentation and any record relating to those) claims ahall be maintained for a period not

- 44 -

ArtuuGw.b less than ten (10) years from the date on which the final claim was submitted to the Fund. B. Upon request by EPA, the Private Settlors and the County shall make available to EPA such records or copies of any such records, subject to the attorney-client privilege, the privilege related to documents or records protected by the attorney work product doctrine, and any other privilege recognized under federal law. In the event Settlors withhold a document as privileged, Settlor* shall provide EPA with the title of the document, the data of the document, the name of the author, the name of the addressee and/ or recipient, a description of the content* of the document, identification of the privilege asserted, and a daacription of the baai* for the claim a**ertad.

XVI . STIPULATED A. Except with raapact to any axteneione agreed to by the Partiae in writing, but not including extenaion* resulting from Settlor* ' pursuit of dispute raeolution under Section XVIII (DISPUTE RESOLUTION), and for any force majeure evente covered by Section XVTI (FORCE MAJEURE) herein, and subject to Section XIII (C) (SITE ACCESS), for each working day that the Private Settlors or the County fail to submit a report or a document or otherwise* fail to commence or achieve the requirement* of thi* consent Decree, the Private Settlors or the County ahall be subject for each such failure on each such day to the impoeition of stipulated penalties as sat forth below. The Private Settlor* shall be jointly and severally liable for their stipulated

- 43 -

ft u u U it , / penalties set forth, in this Section XVI (STIPULATED PENALTIES) . The County shall be solely liable for its stipulated penalties set forth in this Section XVI (STIPULATED PENALTIES). 1. Pra-iect Activities with the exception of monthly progress reports listed in Section IX(A) (REPORTING REQUIREMENTS) of this Consent Decree, each day that the Private Settlors or the County fail to submit a plan or report to be submitted during the course of the work in accordance with the schedule in the Work Plan*, or commence or complete the task* listed in accordance with the requirements of thi* Consent Decree, the Private Settlore and/or the County shall ba subject to the imposition of atipulatedv panaltiae in the following amounta: 4 Day* l - >10 $1,300 per day Daye ll - 30 $3,000 per day After 31 daye $6,000 per day 2. Reports For each day that the Private Settlore or the county fail to submit a progrea* report in accordance with the requirements of Section IX(A) (REPORTING REQUIREMENTS) of this Conaent Decree, or to be established- in the Work Plan, the Private Settlors or the County shall be subject to the imposition of stipulated penalties in the following amount**

Days) 1-14 f 900 per day Days IS - 30 $1,000 per day After 31 days $1,500 per day 3. Failure to Achieve Other Requirements For each working day that the Private Settlors or the County fail to commence or achieve any other schedule regAiirements of this Consent Decree, the Private Settlors or the County shall be subject for each such failure on each such working day to the imposition of stipulated penalties as set forth below:

Days 1-10 $1,500 per day Day* 11-30 $3,000 per day After 31 day* $6,000 par day B. Payment of stipulated penaltiae shall be due and payable within thirty (30) day* following receipt of a written demand for such payment by the United Statae, sent by certified mail, return receipt requeated. In it* demand the United Statae will daecribe the basis for the imposition of the stipulated penaltia* under thie Conaent Decree. Intereet will begin to accrue on atipulatad penaltiee if the penalty amount i* not paid within thirty (30) day* after the Settlore receive written demand by the United Statae unlaae one of the Settlore hae initiated diepute resolution proceduree pursuant to Section XVIII (DISPUTE RESOLUTION). Intereet will be aeseesed at the rate of the current anaualised treaeury bill rate as of the date of the demand* C. Zf dispute resolution procedures are 'invoked, stipulated penalties shall be placed in aa intereat bearing eacrow account pending reaolution of the) dispute, written notice of depoeits into the escrov account shall be sent to the Regional - 47 -

A f\ u u U Hearing Cleric as set forth in paragraph (0) below. Any such account shall be open to audit by the United States. It the dispute ia resolved in favor of the United States, the monies in the approved escrow account shall, including all accrued interest, be transferred to the Hazardous Substance Superfund within thirty (30) days of such decision. D. Payment of stipulated penaltiea to EPA shall be made by cashier's or certified check, which references the Site name, and is payable to the Hazardous Substance Suparfund and shall be mailed to: EPA, Region 3 Attn: Superfund Accounting P. 0. BOX 360515M Pittsburgh, PA 15251 f A copy of the check and transmittal latter ahall be • sent to the EPA Remedial Project Manager and tot Regional Hearing Clerk (3RCOO) U.S. EPA - Region 3 341 Cheetnut Building Philadelphia, PA 1910? E. Accrual of theee stipulated penaltiea shell stop if and when the requirement that wee the aubjact of the penalty haa bean achieved or the United Statee begine performing the Work that was the subject of the demand or Settlors complete performance of such Work, whichever occurs first. P. The imposition of stipulated penalties in accordance with this Section does not preclude the United States from pursuing any other remedies, including the statutory maximum penalty, or enforcement actions which may be available by reason

- 41 -

u ^ 'L u of the Settlors' failure to comply with any of the requirements of thi* Consent Decree, provided, however, that any stipulated penaltie* assessed by EPA and actually paid will be deducted frca any statutory penalty imposed for the same event. G. After the date of the County's execution of this Consent Decree and assuming that this Consent Decree is entered by the Court, the State shall not assert, demand, or seek to collect from the County any stipulated penalty authorized by the October 8, 1987 Notice of Conciliation Proceeding* issued by the state in connection with NPDES Permit No. DEOOS0741. H. Neither the pendency of diapute raaolution proceedings under Section XVIII (DISPUTE RESOLUTION) nor the payment of. panaltiae shall altar the Settlor*' obligation to complete the Work or perform any other obligatione required under thi* Consent Decree. XVII. FQRC« MAJTOM A. The Settlor*' activitiae under thie Consent Decree shall be performed in the manner and within the time limit* sat forth herein, unleee performance ie delayed or prevented by an event arieing solely from cau*ee beyond the control of Settlor* and which could not have been avoided or overcome by the exercise of due> diligence. Increaaed coat* or expeneee associated with implementation of the work called for in this Consent Decree and the economic eircumstancee of the Settlors shall not be considered circumstances beyond the control of the Settlors. The settlors' time to perform the activities or comply with the

- 4t -

A R u u U requirements affected by the force majeure event shall be extended for a period of time equal to the extent of the delay caused by the force majeure event. However, the Settlors shall use best efforts to expeditiously complete the delayed activity c- come into compliance. All elements of the Work not affected by the force majeure event shall continue and ba completed in accordance with the applicable schedule. B. when circumstances are occurring or have occurred that may delay performance or prevent compliance with any obligation under thia Consent Decree, whether or not dua to a force aajeure event, the Settlors shall notify the United statae and the State orally within seven (7) days and in writing a* soon a* poaaible, but in no event more than twenty (20) working day* after learning of any event which Settlor* believe may delay the Work or prevent compliance. Such notice shall deecribes 1. the nature and cauee of the event the Settlor* consider to be force majeure, including, if applicable, a statement of the Settlore' rationale for interpreting such event a* force majeure; 2. the meaaures taken and to be taken by the Settlors to prevent or minimite the delay or non compliance) 3. the) anticipated length of the delay or non compliance)! 4. the) timetable by which various measures vill be implemented to prevent or minimise the delay or noa compliance; and

- 50 - 5. the date by which or the time period within which the Settlors propose to complete the activities as to which the deadline applied. Such notice by the Settlors shall be accompanied by any documentation relating to (1) through (5), above. Failure by the Settlors to comply with the notice requirements of this Section shall constitute a waiver of the Settlors' rights under this Section to assert that the event waa force majeure. The burden of proving that any delay ia caused by a force majeure and the extent of the delay cauaad by the force aajaura shall reat with the Settlors. C. The United State* shall raapond in writing to any notice submitted by the Settlor* pursuant to Section XVII(B) * (FORCE MAJEUREJ of thie Consent Decree, indicating whether the United Statae agraae that the delay or noncompliance wae caused by a force majaura event and approvae the Settlore' proposed data or time period for completion of the delayed activitiae. The United Statae' written approval shall be deemed to be incorporated into thie Conaent Decree. If the United Statee doee not so approve, the United States shall ao atate its reaeone in writing* An extension of time for performance of the obligation directly affected by the force majeure event shall not necessarily juatify an extension of time for performance of a subsequent obligation not directly affected by the force majeure event.

- 51 -

U Hr 0. Delay or non compliance caused by force najeure shall not be deemed a violation of this Consent Decree, nor shall it make the Settlors liable for the stipulated penalties contained in Section XVI (STIPULATED PENALTIES) of this Consent Decree. XVIII. DISPUTE RESOLUTION A. Except as otherwise provided in Section XXII (CLAIMS AGAINST THE FUND AND PAYMENT OF RESPONSE COSTS), all disputes between the Parties arising under thi* Consent Decree shall be resolved according to this Section. If a diaputa arises under this Consent Decree, the EPA Remedial Project Manager and Settlors' Project Coordinators shall firat attempt to reaolve the matter informally. EPA, however, may at any time notify the Private Settlor* and/or the County of diaputa* concerning Work-1 t or Work-2, as may be appropriate. If the EPA Remedial Project Manager and settlor*' Project Coordinators cannot raeolve a difference of opinion with respect to such matter* within two (2) working day*, or, if the Private Settlors and/or the County object to any United Statae' notice of deficiency, notice of disapproval or any other decision made pursuant to this Consent Decree, the Private Settlors and/or the County ahall notify the united States in writing of their objection within fourteen (14) days of receipt of the notice or decision, or of the difference of opiniemu EPA and the Private Settlors and/or the) County ahall then have) fourteen (14) days from the receipt by EPA of the notification of objection to negotiate to reach agreement. If agreement cannot be reached on any iaaus within this fourteen

- 52 - (14) day period, EPA shall within the succeeding ten (10) days provide a written statement of its final decision to the Private Settlors and/or County. The decision of the United States shall be binding unless the Private Settlors and/or the County file a petition with the Court within fourteen (14) days of issuance of EPA's final decision setting forth the matter in dispute and the relief requested. Failure to file a petition requesting relief within the fourteen (14) day period shall conatituta a waiver of this Section XVIII (DISPUTE RESOLUTION) for the disputed final decision. In an emergency, any Party may file a petition at any time. The period for negotiation* may be extended by mutual agreement between EPA and the Private Sattlore and/or the County. In no circumstances shall the invocation of thie paragraph delay • the Work or any part thereof except a* otherwise may be agreed by the Partiae or ordered by the Court. B. Payment of Stipulated penalties with reapact to any disputed matter shall be atayad pending resolution of the dispute. Notwithstanding the stay of payment, Stipulated penaltiee ahall accrue from the firat day of noncompliance with any applicable provision of this Consent Decree. In the event that the Settlors do not prevail on the disputed issue, stipulated peneltiee shall be aeeeeeed and paid ae provided in Sectios»fX (STIPULATED PENALIZES). C. Zn any dispute presented to the Court for resolution involving matters falling within the scops of Section 113(j) of CERCLA, 42 U.S.C. | 9«13(j), the Court ahall affirm the position

- 33 -

Art u u u of the United States unless such position shall be shown, on the administrative record, by the Settlors, to be arbitrary and capriciou* or otherwise not in accordance with law. For any other dispute arising under this Decree, the Court shall determine the appropriate standard of review. C. The failure to specifically reference this Section XVIII (DISPUTE RESOLUTION) in any other provision of this Consent Decree shall not be interpreted aa a waiver of the applicability of this Section. D. The provision* of this Section regarding Dispute Resolution shall not apply to dispute* between the state and the United State*. XIX. BESPOMag AUTHORITY A. Except as provided in Sectiona VIZ (IMPLEMENTATION OF s WORK) and XXZ (COVENANT NOT TO SUE), nothing in thie Concent Decree shall be deemed to limit the authority of the United Statae under Sectione 104 and 104 of CERCLA, 42 U.S.C. f| 9604 and 9606, or the authority of the OSC under 40 C.P.R. I 300.65, or the right of the United Statee to recover the coete of such response under Section 10? of CERCLA, 42 U.S.C. I 9607, or any other legal authority. B. Except as is specifically provided in Section VZZ(I) (lMPLZM«tt*TION OF NOME) herein, so long as the Settlors are performing the work required by this Consent Decree and the work performed is in compliance vita the terms of this Consent Decree, the United States ahall not perform this *ame Work. This

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u 0 ^ L o provision shall in no way limit the United States from oversight of Work performed by the Settlors, including the taking and analysis of duplicate samples. XX. CONSISTENCY WITH NATIONAL CONTINGENCY PLA.N A. The United States, the State and the Settlors agree that the work, if performed in accordance with the requirements of this Consent Decree, is consistent with the provisions of the National contingency Plan, promulgated pursuant to Section 105 of CERCLA, 42 U.S.C. i 960S, and all actions taken or omitted in performing the Work are afforded all protection provided in Section 107(d) of CERCLA, 42 U.S.C. | 9607(d). XXI. COVENANT NOT TO 3CT A. Except a* specifically provided in thie Section, the United Statae and the State covenant not to aue the Settlors for Covered Matter*. For the purposes of thie Section only, the term 'Covered Matters* shall mean any and all civil claim* against, and civil liability of the Settlor* to the United Statae and the State for cauaae of action ariaing under Sectione 10« and 107(a) of CERCLA, as amended, 42 U.S.C. f| 9«0< and 9607(a), and the provision* of *tate atatutory lav, relating tot 1. Implementation of the Work for Operable Unit one and Operable unit Two, (including collection, treatment and monitomimsj of groundvatar underlying the Oelavare Sand and Gravel Superfund Site) as set forth in ROD-l and ROD-2 and more specifically described in Scope of Work-1, Scope) of Work-2, and the Work Plans submitted to and approved by EPA;

- 33 -

AriuuU 2. The implementation and continuation of operation and maintenance activities pertaining to the Work for Roo-1 and ROD-2? 3. sediments in Army Creek, and upgradient trenching and diversion and/or treatment as specified in ROD-l; 4. Payment of Oversight costs and response costs incurred by the United States and/or the state except to the extent that the Settlors are obligated to pay such costs under Section XXII(H) and (I) (CLAIMS AGAINST THE FUND AND PAYMENT OF RESPONSE COSTS) herein; and 5. Damages for injury to, destruction of, or loaa of natural reeources, including the reasonable costs of assessing such injury, destruction, or loss of natural reeourcee, resulting * from the release or threat of releaee of hatardoue substance* from (a) the Site, and (b) with respect to the Delaware Sand and Gravel Landfill Superfund Site, releasea or threatened releases of hazardous substance* which cauae or contribute to ground water contamination and contamination of Army Creek and the Army Creak habitat. 'Natural resources* shall have the meaning assigned to them by Section 101(16) of CERCLA, 42 U.S.C. I 9«01(1«). B. Per purposes of this Section, 'Covered Kattere*, deee not inclose) s 1. .Claims based on a failure by the. Settlors to meet the requirement* of this Coneent Decreei 2. Subject to paragraph A above, claims for

- S< - injunctive relief and response costs incurred pursuant to Section 121(C) Of CERCLA, 42 U.S.C. § 3621(c); 3. Criminal claims; and 4. Claims based on liability for hazardous substances removed from the Site. C. This covenant not to sue the Private Settlors and the County shall take effect upon approval by EPA of completion of the construction phase of Work-1 and Work-2 respectively, payment to EPA of the sum specified in Section XXII(H) (CLAIMS AGAINST THE FUND AND PAYMENT OF RESPONSE COSTS AND NATURAL RESOURCE DAMAGES) for past response costs incurred by the United States, and payment of the sum specified in Section XXII(K) for damagaa for injury to, deatruction of, or lose of natural reaourcas incurred by the United State* and the State. The United States or the State shall not initiate any action for covered matters while the Private Settlors or the County are pursuing completion of Work-1 and Work-2 raapactivaly and are otherwise in compliance with thi* Concent Decree. D. A determination regarding certification of completion will be made by EPA within one (1) year of *ucceeeful completion of the construction phaaa of the Work-1 and Work-2, respectively. *V Votvithstanding thi* covenant not to eue, Settlor* ahall not betesjcitled to the protection afforded by thie covenant not to sue vita respect to any reeponee actions that EPA undertakae or determine* are necessary pursuant to Sections VII(I)

- 57 - (IMPLEMENTATION OF WORK), VIII (U.S. EPA PERIODIC REVIEW), or XV : (STIPULATED PENALTIES). F. Notwithstanding any other provision in this Consent Decree, the United States and the State reserve their right to institute proceedings in this action or in a new action seeking (1) to compel Settlors to perform any additional response work for Covered Matters, (2) reimbursement of the United States' response costs, or (3) damage* for injury to, destruction of, or loss of natural reaourcea if: 1. for procaadinga prior to EPA certification of completion of the remedial action; a. condition* at the Site relating to Covered Matter*, previously unknown to the United Statae or the State, * are discovered-, after the entry of thie Concent Decree; or b. information i* received, after the entry of thi* Concent Decree; and c. the** previously unknown conditione or information indicatae that the remedial action taken i* not protective of human health and/or the environment or, with reapact to proceedings or actione to recover therefor, that there is injury to, destruction of, or loes of natural reaourcea that was previously unknown; or a. subsequent to the EPA certification of completion of the remedial action, a. conditions at the Sits relating to Covered Matters, previously unknown to the United States or the State,

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A ri u 0 U s J U are discovered after the certification of completion by EPA Region III; or b. information is received, after the certification of completion by EPA of Worlc-1 and Work-2; and c. these previously unknown conditions or information indicates that the remedial action taken is not protective of human health and/or the environment or, with respect to proceedings or actions to recover therefor, that there is injury to, destruction of, or loss of natural resources that was previously unknown. 3. Knowledge and information in the poaaassion of the state shall not be imputed to the United Stataa and knowledge and information in the poaaassion of the United • State* shall not be imputed to the State. G. Notwithstanding any other provision in thi* Concent Decree, the covenant not to sue in thi* section shall not relieve the Sattlore of their obligation to meet and maintain compliance with the requirementa set forth in thie Conaent Decree, including the requirement* to be included in the Work Plan for Operable Unit One and Operable Unit Two, which are incorporated herein. The covenant not to sue provided by thi* section* small be subject to the satisfactory performance by Settlor** of their obligationa under thia Conaent Decree. H. nothing in thia Consent Decree shall constitute or be construed as a release or a covenant not to sue with regard to Non-Settlors.

A A' U u U 4 J i I. Excect as expressly provided in this Consent Decree, each party reserves all rights, claims and defenses it has under CERCLA, or any other law or in equity. J. Nothing in this Section or any other Section of this Consent Decree shall be deemed an admission of liability (or of an element of liability) or a waiver by any Settlor of any defense available under CERCLA, RCRA or any other statute or the common law to any claim for relief in any proceeding subsequently instituted by the United Statee or the State in connection with the Si . Settlors, however, shall not be able to conteat their -oligation to comply with the terms of this Consent Decree but shall have the right to contest _ whether they have complied with those obligatione. Nothing in •• thi* Section shall relieve the United States or the State of any applicable requirement to establish the element* of any statutory or common lav claim under which it seeks to obtain any additional relief, not authorized by thia Consent Decree, from the Settlore in connection with the Site. In the event the United States, or the State, secures additional relief in an action instituted pursuant to Section XXI(F)- (COVYXAMT MOT TO SUE) hereof, pursuant to Section 122(b)(4) of CERCLA, as amended* the) Pond shall be subject to an obligation for subsequent rams ill it action* at the Sits only to the extent that sue* subsequent actions are necessary by reaeon of failure of the original remedy. Such obligation shall be in a proportion equal to, but not exceeding, the proportion

- 60 - contributed by the Fund for the original remedial action pursuant to the Preauthorization Documents referenced in Section XXII (CLAIMS AGAINST THE FUND AND PAYMENT OF RESPONSE COSTS). K. For and in consideration of the covenants and promises made herein, the Settlors waive, release, and covenant not to sue or otherwise assert any causa of action, claims, or demands against the United State* and the State with reapect to the Site, or for expenses related to this consent Decree, including any claim* purauant to Section I06(b), of CERCLA, 42 U.S.C. | 9«06(b), or any other provision of law, directly or indirectly, or againat the Hazardous - Substances Superfund established by Section 121 of CERCLA, 42 , * U.S.C. f 9621» or any other claims againat the United Statae and the State for expense* related to thie Conaent Decree, except that Sattlore may submit the claims described in Section XXII (CLAIMS AGAINST THE FUND AND PAYMENT OP RESPONSE COSTS). The Settlors' waiver, releaee, and covenant not to sue under thie paragraph X ahall not apply in the event that the United States or the State inetitutee an action againat the Settlors under Paragraph P hereof or with respect to any matter ts>vhich the) covenant of the United Statae or the State pursuant to Paragraph A hereof ie found inapplicable by the court.

- 61 - XXII. CLAIMS AGAINST THE FUND AND PAYMENT OF RESNE COSTS AND NATURAL RESOURCE DAMAC A. In accordance with the Preauthorization Decision Document attached to this Consent Decree as Exhibit 7, the Private Settlors may submit a claim for reimbursement to the Hazardous substance Superfund (the "Fund*) for up to ten percent (10%) of the costs incurred in completing Work-l, excluding any expanses incurred for Operation and Maintenance of Work-1. In no event shall the Settlors' claim against the Fund exceed the sum of $2,000,000.00, unless the amount preauthorized is modified pursuant to paragraph C of this Section. The eligibility of claim* shall date from the effective data of the Preauthorization Deciaion Document. f B. in accordance with Exhibit I, the Preauthorization . Decision Document, the County may submit a claim for reimbursement to the Hazardou* Subatance Superfund (the "Fund*) for up to forty percent (40%) of ite coets incurred in completing Work-2, including expanee* incurred for the pumping and treating of groundwater. In no event ahall the New Castle County'* claim against the Fund exceed the sum of $2,000,000.00, unless the amount preauthorised ia modified pursuant: to paragraph c of thie Section. The eligibility of claims, email date from the effective date of the Preauthoriiation Decision Document. C. If it is subsequently determined by EPA that it is neceesary to modify the actions that EPA preauthorited, or if it becomes apparent that the project's costs vill exceed the - 62 -

Af\CuG*34 approved costs as set out in the Preauthorization Decision Document, or if the Settlors undertake additional Work required by EPA pursuant to Sections VI (WORK TO BE PERFORMED), VII (IMPLEMENTATION OF WORK), or VIII (U.S. EPA PERIODIC REVIEW), the Settlors may submit to EPA a revised application for preauthorization. EPA will consider requests for preauthorization from the Settlors in a timely manner and subject to the availability of funds appropriated for response actions from the Hazardous Substancea Superfund and will, upon submission of all required documentation, revise the preauthorization to cover ten percent (10%) of Private Settlors' reasonable and necessary coat* to implement work-1, and forty percent (40%) of the County'* reaaonable and t necessary coats to implement Work-2. D. The Settlors' claim* againat the fund shall cover only the Settlors' coat* of remedial action. The Settlor*' claim* againat the Fund shall not include any of the United statea' oversight coat*, inveetigatory coete or paet reaponae coat* that were incurred prior to the lodging of thie Consent Decree. Reimbursement from the Fund of the amount claimed by the settlor* shall be subject to the applicable claims and audit procedures specified in the Preauthorization Decision Document;*. E. Any claims for reimbursement against the Fund shall not exceed ten (10%) of coeta incurred in completing Work-1; and forty (40%) of coeta incurred in completing Work-2,

- 63 - including costs incurred for pumping and treating groundwater for the first ten years of operation of the treatment plant. Settlors may present a claim against the Fund only after the claim has been presented to any person Known to them who may be liable under Section 107 of CERCLA and which claim has not been satisfied within sixty (60) days. If the first claim was denied by the responsible party or not responded to, and EPA agrees that there ia no reason to believe that subsequent claim* would be honored by such responsible party, the denial of the firat claim, or lack of reaponaa, ahall be conaidared denial of every subsequent claim. If EPA denies a claim in whole or in part, EPA ahall notify the Settlor in writing of - the reason for such denial. If the Settlor ie dissatisfied » with EPA's decision to deny any claim againet the Fund, in whole or in part, the Settlor may demand an administrative hearing before an administrative lav judge ae provided in Section 112(b) of CEftCLA, 42 U.S.C. } 9612(b). F. Payment of any claim to the Settlore shall be subject to the subrogation of the rights of the Settlors as claimant* to the United States, to the extent to which the Settlore' reeponsej costs are compensated from the Fund.

Furthert the) Settlors ahall aaaiat in any coat recovery action which may be> initiated by the United States. The Settlors and the Settlors' contractors shall furnish the personnel, services, documents, and materials needed to assist EPA in the collection of evidence to document work performed and costs

- 64 - expended by the Settlors or the Settlors' contractors at the Site in order to aid in cost recovery efforts. Assistance shall al*o include providing all requested assistance in the interpretation of evidence and costs, and providing requested testimony. All of the Settlors' contracts for implementing the Preauthorization Decision Document shall include a specific requirement that the contractors agree to provide this cost recovery assistance. <3. The Settlors shall not make any claim* againat the Fund except a* provided in thia Section. H. within thirty (30) day* after the entry of thia Conaent Decree, the Settlor* shall jointly and severally pay the United Statae Environmental Protection Agency the sum of » $1,000,000.00, which represents a portion of pa*t response cost* incurred by the United Statae in responding to the release and threatened release of hazardous substancea at the Site. Such cost* ar* listed and described in Exhibit 9 which is attached hereto and incorporated by reference. The payment to EPA shall be by certified check payable to lUxardoue Subrtanc* Superfund' and shall be sent by certified mail, return receipt requested, tot EPA, Region 3 Attentions Superfund Accounting P. 0. BOX 360515M Pittsburgh, PenneyIvania 13231 The check shall reference the Site name. A copy of the cover letter and the check ahall be sent to the EPA Remedial Project Manager and the Regional Rearing Clerk (3RCOO), U.S. - 69 -

o/ Environmental Protection Agency, Region 3, 841 Chestnut Building, Philadelphia, Pennsylvania 19107, and to Attn: Rosemarie Pacheco, Environmental Enforcement Section, U.S. Department of Justice, P. o. Box 7611, Ben Franklin Station, Washington, o.C. 20044. I. The Settlors shall be jointly and severally liable for and shall pay oversight costs of the United States incurred in overseeing implementation of Work-1 and of Work-2 to assure compliance with the term* of thi* Consent Decrea and CERCLA and the NCP. Payments of all such coat*, which costs must not be inconsistent with the NCP, shall be made on an annual basis and within sixty day* of the submission of itemized cost statement*. The Settlors shell be given timely • and reasonable opportunity to review supporting document* for such submittal*. In the event the Settlore dispute claimed oversight costs or any portion thereof, auch coets, to the extent found in Dispute Resolution to be payable, shall be paid within thirty (30) daye after the final deciaion in the dispute reeolution procedure, with intereet running from thirty (30) days after submission of the original itemized coet statement until the date of payment. Such intereet shall be calculated at the then prevailing intereet rate on fifty* two weeJKV.S. Treasury MX bills maturing in September of each year. The United States' beet eetimate is that its oversight coets through the construction phase of Work-1 and Work-2 will be in the range of $1,000,000.00. As a convenience to the

- 66 - Settlors, EPA shall maintain two separate accounts for oversight costs, one for expenses incurred for Work-l and another for expenses incurred for work-2. Billing for costs incurred for Worfc-1 will be directed, to the Private Settlors and billing for costs incurred for Work-2 will be directed to the County. J. If oversight costs are outstanding at the time the United States plans to certify completion pursuant to Section XXIII(B) (EFFECTIVE AND TERMINATION DATES SUBSEQUENT MODIFICATIONS), the Settlors shall, within sixty (60) daya of the submission of an itemized coat atatemant and before termination of this Consent Decree, pay such oversight cost*. .. In the event the Settlor* dispute claimed oversight coat*, * such costs, to the extent found in Dispute Resolution to be payable, shall be paid within thirty (30) daye after the final decision in the dispute raaolution procedure, with intaraat running from thirty (30) daye after submission of the original itemized coat atatament until the date of payment. Such intaraat shell be calculated at the then prevailing intaraat rate on fifty-two week U.S. Treasury MX bill* maturing in September of each year. The United State* shall not certify completion until such time ae all coete required to be paid under tad* consent Decree plue intereet are paid by the Settlors. K. within thirty (30) days after the entry of thia Conaent Decree, the Settlors shall jointly and aeverally pay

- 67 -

A rt u u u H J :> the United States Department of the Interior (»DOI*) the sum of $266,000.00, the United States Department of Commerce, National Oceanic and Atmospheric Administration ("NCAA") the sum of $266,000.00, and the Delaware Department of Natural Resources and Environmental Control ("DNREC*) the sum of $268,000.00, which represents a portion of the damages for injury to, destruction of, or loss of natural resources incurred by the United state* and the state reaulting from the release and threatened release of hazardou* substances at the Site and the Delaware Sand 6 Gravel Landfill Superfund Site as referenced in Section XXI(A)(5)(COVENANT NOT TO SUE). The payment to DOI shall b* by certified check payable to "U.S. f Department of the Interior* and ahall be sent by certified . mail, return receipt requested, to: Office of Fiscal servicee Office of the Secretary U.S. Department of the Interior Kail Stop 3237 1S49 c street, tf.w. Washington, D.C. 20240 The check shall reference the Site name. A copy of the cover latter and the check shall be sent to Director, Office of Environmental Affaire, U.S. Department of the Interior, lt4* c street, V.V.—Room 2340, Washington, D.C. 20340. The payment to NOA*small be by certified check payable to.*U.S. Department of Commerce, NOAA* and shall be sent by certified mail, return receipt requeeted, tot General Counsel National Oceanic and Atmospheric Administraticn Herbert Hoover Building, Room 5814 14th and Constitution Avenue, N.w. Washington, D.C. 20230 The check shall reference the Site name. Copies of the checks to DOI and NCAA shall be sent to Attn: Rosemarie Pacheco, Environmental Enforcement Section, U.S. Department of Justice, p. o. Box 7611, Ben Franklin station, Washington, D.C. 20044. The payment to DNREC shall be by certified check payable to 'Delaware Department of Natural Reaourcea and Environmental Control* and shall be sent by certified mail, return receipt requested, to: Legal Office I Delaware Department of Natural Resource* and Environmental Control State of Delaware 39 King* Highway Wilmington, Delaware 19901 The check shall reference the site name. XXIII. EFFECTIVE AND TERMINATION DATES SUMEQUEMT-JJQQIF.ICAT.IQM. A. This Consent Decree ahall become affective upon the date of its entry by the Court. B. The provisions of thi* Conaent Decree shell terminate and be deemed satisfied upon the Settlors' receipt of writtsm) notice from the United States that the Settlor* have demonstrated to the satisfaction of the United Statae that all of the terms of this Consent Decree have been completed and all oversight costs and atipulated penalties required to be paid under this consent Decree have been paid,

- 69 - provided, however, that Operation and Maintenance as required by each Work Plan and Sections VI (WORK TO BE PERFORMED) , vni (PERIODIC REVIEW) , XIII (SITE ACCESS) , XIV, (SAMPLING AND DATA/ DOCUMENT AVAILABILITY) , XV (RECORD PRESERVATION) , and XIX (RESPONSE AUTHORITY), XXI (COVENANT NOT TO SUE) and XXV (CONTRIBUTION PROTECTION) of this Consent Decree, shall survive termination. C. Except as specifically provided in Section vii(D) (IMPLEMENTATION OF WORK) and Section XI (D) (DESIGNATED REMEDIAL PROJECT MANAGER AMD PROJECT COORDINATORS) , no modifications, to which the Parties agree, shall be made to this Decree without written notification to tha Court and written approval of the United Statae, the State, and the Settlor*. XXIV. US* OF A. Settlor* specifically deny any violation, fault or liability under any federal, atate or local law or any legal liability whatsoever in connection with the Site or otherwise. Nothing in thie Conaent Decree is intended by the Partiee to be, nor shall it be, an admission or adjudication of facta or law, an estoppel or a waiver with respect to any matter, act, claim, right or defence by the Settlors for any purpose, or evidence* o* any wrong doing, misconduct, fault or liability to any person on the part of the settlors. Accordingly, it is the intention of the United States, the) Stats, and the Settlors that, with the exception of any proceeding to enforce

- 70 - this Consent Decree or for contribution or indemnity by or against the Settlors, this Consent Decree shall not be admissible into evidence in any other proceeding except that it nay be admissible in: (l) a judicial or administrative proceeding between the Settlors and any insurance company concerning the obligation of such insurance company to pay any amounts expended by the Settlors or to satiafy any liability of Settlors hereunder; and (2) in any administrative or judicial proceeding arising from Settlors' claim* against the Fund brought pursuant to Section XXII (CLAIMS AGAINST THE FUND AND PAYMENT OF RESPONSE COSTS) . XXV. COMTBIBUTIQM r Each Settlor shall hava the benefit of the contribution * protection prqvided under Section 113(f) and Section 122(h)(4) of CERCLA, 42 U.S.C. i 9613 (f) and each of the Settlor* agree that if a suit or claim for contribution i* brought againat it for matter* covered by thie Concent Decree, it will timely notify the United Statae and the State of the inetitution of such suit or claim. It ie also agreed that the United State* and the state ehall not be under any obligation to aaaist the settlors in any way in defending againat such suits for contribution. Nothing in this Consent Decree shall affect the settlors* right to seek recovery of expenditures made in compliance with this Consent Decree by way of indemnity or contribution except as againat the United States or the State.

- 71 - XXVI. RETENT^flN OF JURISDICTION, A. This Court will retain jurisdiction for the purpose of enabling any of the Parties to this Consent Decree to apply to the Court at any time for such further order, direction, and relief as may be necessary or appropriate for the implementation, construction or modification of this Consent Decree, or to effectuate or enforce compliance with ita terms, or to resolve disputes in accordance with Section XVIII (DISPUTE RESOLUTION) hereto. a. The United States, the State, and the Settlors retain the right to enforce the term* of thi* Concent Decree and take any action authorized by federal or atate law not inconsistent with itc terms to achieve or maintain compliance » with the terms, and conditions thereof. XXVII. QTHCT PHQVT3IQMS A. Thie Concent Decree may be executed in any number of counterparts, each of which shall be deemed an original but all of which taken together ahall conctitute one and the sa instrument. B. All *ection headinge herein are for convenience only and are in no way to be conetrued as part of this Consent Decree, oar as a limitation on the scops of, the proviaion to which tfcay may refer. C. Failure or delay of the United States or EPA to provide to the settlors any approvals or notices within designated time periods specified in this Consent Decree shall

- 72 -

A R u u 0 ^ k 4 not be construed or interpreted as approval by the United States or EPA of any matter, except as specifically provided in section xvil(C) (FORCE MAJEURE) of this Consent Decree. D. This Consent Decree represents the entire agreement and understanding between the Parties regarding the matters set forth herein and shall supersede all prior drafts, writings, negotiations, and discussions between the Parties. E. This Consent Decree shall be lodged with the Court for a period not less than thirty (30) daya for public notice and comment in accordance with Section 122(d) and (i) of CERCLA, 42 U.S.C. f 9622(d) and (i), and 2t C.F.R. | 50.7. The United States reserves the right to withdraw or withhold its consent if the comments regarding the Consent Decree ' * disclose facts, or considaratione which indicate that the Consent Decree is inappropriate, inadequate or improper. Settlors consent to the entry of thie Concent Decree without further notice. F. Each Settlor ahall identify, on the attached signature page, the name and addreee of an agent who ic authorized to accept service of proceee by mail on behalf of that party with respect to all matters arising under or ralatins) to this Consent Decree. Settlors hereby agree to accept service in that manner and to waive the.formal service requirements set forth in Rule 4 of the Federal Rules of Civil Procedure, including service of a summons, and any applicable local rules of this court.

- 73 - G. In the event of conflict between or among the Consent Decree and the exhibits annexed, the Consent Decree shall control. Each work Plan or Scope of work, as applicable, shall govern its respective Preauthorization Decision Documents. H. Upon entry of the Consent Decree, NPDES Permit Mo. DEOOS0741 shall be revoked and the October 8, 1987 Notice of Conciliation Proceeding* issued by the State shall be withdrawn. The County consents to the revocation of the permit and the withdrawal of the Notice. Notwithatanding the foregoing, the State reserves the right to enforce Paragraph « of the Conaant Order entered in Wilson v. county of New castle, c. A. No. 37C-SE6, Kant County Superior Court, to fund * Delaware Nature Society's Stream watch Program. XXVtXX. COMMUMTTY RELATIONS A* reasonably requested by EPA or the State, the Settlors shall participate in the preparation of all appropriate information disseminated to the public and in public seetinga which may be held or cponeored by EPA or the State to explain activities at or concerning the Site.

TH*im*TiEJ urn* INTO THIS CONSENT DECRIE RELATING TO THE ARKs> Cim LANDFILL SUFERFUND SXTB.

- 74 - FOR STATES OF AMERICA

DATS BAERY- M.*-HaPSMMfr Acting Assistant Attorney General Environment: and Natural Resources Division U.S. Department: of Justice Washington, D.C. 20530

. 1441 DATE/ MICHAEL D. MCZHTYRZJ Attorney Environmental Enforcement section U.S. Department of Justice Box 7611 Ben Franklin Station Washington, D.C. 20044 (202) 514-S508 WILLIAM C. CARPENTER, JR. United Statae Attorney District of Delaware

DAT: Assistant United State* Attorney J. Caleb Bogg* Federal Building 344 King Street, Room 5110 Wilmington, Delaware 19801 (302) 573-6277

DA JAMES M. STROCK Assistant Administrator U.S. EPA 401 M Street, S.w. Washington, D.C. 20460

DATS EDWIN B. ERICSSON Regional Administrator U.S. EPA Region IH 341 Chestnut Building Philadelphia, PA 19107

- 75 -

Artuuu FOR THE STATE OF DELAWARE:

DATE EDWIN H. CLARK, II, Secretary State of Delaware Department of Natural Resources and Environmental Control 89 Kings Hwy., P.O. Box 1401 Dover, DE 19901

DATE / ' MICHAEL F. FOSTER State Solicitor Department of Justice 820 N. French Street Wilmington, DE 19801

DAT J $$NNE L . LArfGDON *O Deputy Attorney General Department of Natural Resources and Environmental Control 89 Kings Hwy., P.O. Box 1401 Dover, DE 19901 - 76 -

A K u U U Mr Lt 0 DATE' MARCIA S. MULKEY. Regional Counsel U.S. EPA Region III 341 Chestnut Building Philadelphia, PA 19107

DATE MARIA* PARISI VTCKERS Assistant Regional Counsel U.S. EPA Region III 341 Chestnut Building Philadelphia .PA 19107

DATE General counsel National Oceanic and Ataospharic Administration U.S. Department of Commerce Washington, D.C. 20230 FOR THE STATS OF DELAWARE:

DATE EDWIN H. CLARK, II, Secretary State of Delaware Department of Natural Resources and Environmental Control 39 Kings Highway Dover, DE 19901

DATE JEANNE L. LANGDON Deputy Attorney General State of Delaware Department of Natural Resources and Environmental Control 39 King* Highway Dover, OS 19901 (302) 736-4«3« - 76- - FOR THE DEFENDANTS:

- 77 -

ii u U U K- 5 U United states v. BP America Inc., efr al. and State of Delaware v. BP America, Inc., et al. Consolidated Civil Action Nos. Consent Decree United States District Court District of Delaware

September 21, 1990

BP AMERICA INC.

BY: Warren F. Lory,Manager Acquisition and Divestitures

9097

^ 5 i United States v. BP America, Inc., et al. and State of Delaware v. BP America, Inc., et al Consolidated Civil Action Nos. Consent Decree United States District Court District of Delaware

September 24. 1990 Date

The Budd Company Name of Defendant

("Signature)

D. Hecker. Vice President & General Counsel (name and title)

U u U L/ 0 L. BP AmerJE?. Inc.. et al. and Stata of flglaware v. BP America. Inc.. et al. Consolidated Civil Action Nos. _ Consent Decree United States District Court District of Delaware

September 14, 1990 Date

CHAMPLAIN CABLE CORPORATION Name of Defendant

By (Signature)

F. Torvend. President/CEO (Please type name and title here)

PJUC-871* - 09/12/90 - llillaa United States v. BP America, Inc., et al. and state of Delaware v. BP America, inc., et al. Consolidated Civil Action Nos. CONSENT DECREE United states District court District of Delaware

September 20, 1990

Day International Corporation (formerly Electric Hose & Rubber Company1 Name of Defendant

By: XJohn S. Pyfce, Jr. Vice President and Secretary

Art u u U United States v. BP America, Inc., et al. and State of Delaware v. BP America, Inc., g£ Consolidated Civil Action Nos. Consent Decree United States District Court District of Delaware

September 19.1990 Date

E. I. DU PONT DE NEMOURS AND COMPANY

By:

Dr. Richard A. Romanelli Director Safety

A R u U u s- United states v. BP America, Inc., eJt and State of Delaware v. BP America, Inc., et al. Consolidated Civil Action Nos. Consent Decree United States District Court District of Delaware

Date 7 /

Gates Engineering, Inc./GEC Industries, Inc. Name of Defendant

BY: X_ (Signature)

Thomas J. Puette Director - Regulatory Affairs THE GLIDDEN COMPANY, as predecessor in interest to GEC Industries. Inc. United States V. BP America, Inc., et aj. and State of Delaware v. BP America, Inc., e£ a_l. Consolidated Civil Action Nos. Consent Decree United States District court District of Delaware

September 21, 1990 Date

General Motors Corporation Name of Defendant

By: (Signature)

Mark Heater. (Please type name and title here)

/ United States v. SP America, Inc., et al. and State of Delaware v. BP America, Inc., et al Consolidated Civil Action Nos. Consent Decree United States District Court District of Delaware

September 27, 1990 Date

Hercules Incorporated Name of Defendant xH/A/£- B " TSTgnature)

(Please type name and title here

« A' o o U ^ j 6 United States v. BP America, Inc., et al. and State of Delaware v. BP America, Inc., et al. Consolidated Civil Action Noa. Consent Decree United States District Court District of Delaware

September 20, 1990 Date

ICI Americas Inc. Nam* of Defendant

(Signature)

B. H. Lochtenberg, Chairman (Please type tuuu and title here) United States v. BP America, Inc., et al. and State of Delaware v. BP America, Inc., §_£ al. Consolidated Civil Action Nos. Consent Decree United States District Court District of Delaware

September 24, 1990 Date

MOTOR WHEEL CORPORATION

By:: A (L Dale R. Martin, Esquire Vice President, Secretary and General Counsel

u United States v. BP America, Inc., ej; al. and State of Delaware v. BP America, Inc., et Consolidated Civil Action Nos. Consent Decree United States District Court District of Delaware

Date T

Chrysler Corporation Name of Defendant

Lynn K. Buhl, Staff Counsel (Please type name and title here)

A ii u U G 4 6 I United States v. BP America. Inc.. et al. and St^te of Delaware v. BP America. Inc.. et al Consolidated Civil Action Nos. Consent Decree United States District Court District of Delaware

September 19, 1990 Date

NEW CASTLE COUNTY Name of Defendant

Robert L. Maxwell, Acting County Executive (Please type name and title here UNITED STATES V. BP AMERICA, INC., ET AL. AND STATE OP DELAWARE V. BP AMERICA, INC., ET AL. CONSOLIDATED CIVIL ACTION NOS. CONSENT DECREE UNITED STATES DISTRICT COURT DISTRICT OP DELAWARE

2fi 1 9 Q fl Date

SCA Services, Inc. SCA Services, Inc.

Signature

H. Alfred Ryan. Regional Environmental Counsel (Please'type name and title here) United States v. *? America, Inc., at and Stata of Delaware 7. BP America, Inc., §£ il< Consolidated civil Action tios. Consent Decree united States District Court District o£ Delaware

Date '

of Defendant

Jt* (Signaturena )

(Please type name) and title here)

t\ Pv U U UNITED STATES V. BP AMERICA, INC., ET AL. AND STATE OP DELAWARE V. BP AMERICA, INC., ET AL. CONSOLIDATED CIVIL ACTION NOS. CONSENT DECREE UNITED STATES DISTRICT COURT DISTRICT OP DELAWARE

September 26. L99Q Date

Mananomont nf riolauaro. Tnr gement of Delaware, Inc

Signature

Dennis II. Grim, President (Please type name and title here)

U u U 4 0 United States v. 3P America, Inc., et al. and State of Delaware v. BP America, Inc., et al. Consolidated Civil Action Nos. Consent Decree United States District Court District of Delaware

September 21, 1990 Date

Stauffer Chemical Company Name of Defendant

(Signature)

(Please type name and title here) Uniced States of America v. BP America, Inc., ££ and State of Delaware v. BP America, Inc., eg aj. Consolidated Civil Action Nos. Consent Decree United States District Court District of Delaware

Date

WESTVACO CORPORATION Name of Defendant

By: (Signature)

V. S. LUKE Senior Vice President Manager, Bleached Board Division

u UNITED STATES OF AMERICA, INC., s£ al. and STATE OF DELAWARE V. BP AMERICA, INC., fit CONSOLIDATED CIVIL ACTION NOS. CONSENT DECREE UNITED STATES DISTRICT COURT DISTRICT OF DELAWARE

September 21, 1990 Date

Seton Company on Behalf of Wilmington Chemical Corporation Name of Defendant

irfc P^Ma jia^re. Bag. r vice Prgald»n+- and Secretary of Seton (Please type name and title here) Company

« iv u u u ^/ 0 u THIS CONSENT DECREE (C.A. No. 99- ) IS HEREBY ENTERED AND MADE AN ORDER OF THIS COURT THIS ^iA*" DAY OF

-*ITED J STATES DISTRICT TC^URT —JUDGE

4 TRUE COPTi ATTEST! AL

CLBRI

,*

- 78 - Attachments to the Army Creek Consent Decree:

Exhibit 1: Record of Decision for OU-1

Exhibit 2: Record of Decision for OU-2

Exhibit 3: Army Creek Remediation, Scope of Work 1 (Separate Binder)

Exhibit 4: Army Creek Remediation, Scope of Work 2

Exhibit 5: Work Plan for Scope of Work 1

Exhibit 6: Work Plan for Scope of Work 2

Exhibit 7: Preauthorization Decision Document for Private Settlors

Exhibit 8: Preauthorization Decision Document for New Castle County

Exhibit 9: Cost Summary Report

^v / m X K S H RECORD OF DECISION REMEDIAL ALTERNATIVE SELECTION

Site: Army Creek Landfill Site, New Castle County, Delaware Data Reviewed The underlying technical Information, unless otherwlsed specified, used for analysis of the coat-effectiveness and feasibility of remedial alternatives is included in the following documents end project correspondence. I have been briefed by my staff of their contents, and they form the principal basis for my decision of the appropriate extent of remedial action. Feasibility Study for the Army Creek Landfill, New Castle County, Delaware, (Roy P. Weston, Inc., July 1986) Endangerment Assessment, Army Creek Landfill (Richard L. Zambito, U.S. E.P.A. Region III, July 1984) Hydrogeochemical Studies at a Landfill in Delaware (Mary Jo Baedecker : and Michael A. Apgar, 1984, Studies In Geophysics. Groundwater Contamination, National Academy Press) Recommendations by the Delaware Department of Natural Resources and Environmental Control Staff summaries and recommendation* Description of Selected Remedy * Aa initial operable unit for source control* to be Implemented in a two-phased approach. Pnase 1 ' Inatall a RCRA type cap to minimize infiltration of rainwater. Capping of the landfill will include site clearing, regrading of the existing cover surface, adding soil backfill to achieve grade*, installing the cap with gas vents, and construction of drainage ditches to direct run-off away from the landfill. * Continue operation of the downgradient recovery well network. * Evaluate the capping system and the downgradlent pumping network for five years after the cap la installed to a*aess effectiveness of the system during operation. Thia evaluation will Include, but not be limited to, monitoring water levels, pumping rate* and water quality. -2-

Phase 2

* After the five year evaluation period, a determination will be made on whether to install upgradient controls to intercept lateral groundwater inflow on the northwestern boundary of the landfill.

* Continue monitoring the water levels, pumping rates and water quality as in Phase 1.

* Operation and maintenance (0 & M) will include as a minimum, regular inspactiona and, aa necessary, repairs to the RCIA cap. The groundwater recovery system will be monitored to aaaure that It 1* capturing the contaminated plume. Selection of a treatment alternative for the groundwater recovery well discharges has not been made at this time and will be the subject of a second operable unit decision document in the future. A groundwater treatment remedy has not been selected, because the final NPDES permit has not been issued. In addition, the Remedial Investigation/Peaaibllity Study (RI/FS) at the Delaware Sand 4 Gravel Superfund site adjacent to Army Creek Landfill, haa not been completed. It 1* our intention to combine the remedial action* for the*e two site* wherever coet-effeetive. Also being deferred at thia time ia a decision on appropriate remedial measures for sediment* in Army Pond. Thi* decision will be made at the same time aa groundwater treatment 1* considered and after further analysis 1* accomplished regarding the actual impact* on Army Pond. Declaration* Consistent with the Comprehensive Environmental Re*ponce and Compensation and Liability Act of 1980 (CERCLA) (42 U.S.C. f 9601-9657) and the National Contingency Plan (40 C7R Part 300), I have determined that the remedial action described above, together with proper operation and maintenance constitutes a coat-effective remedy which mitigate* and minimize* damage to public health, welfare, and the environment. The remedial action provide* for capping the site, continuing operation of existing dovngradlent groundwater recovery well*, and the installation of upgradient groundweter control* in the future a* neceaiary and, therefore, minimize* the threat of further contamination of the environment. The remedial action doea not affect or violate any areas. A portion of the remedy may encroach slightly into the floodplain at the south end of the site. If during detailed deeign, survey work establishes thia, special measures will be taken to minimize the encroachment and to protect the remedy. The State of Delaware has been consulted and agree* with the approved remedy* In addition, the action will require future operation and maintenance activities to ensure the continued effectlvene** of the ram*die*. Theme activities will be considered part of the approved action and eligible for Truat Fund monies for a period of six months following completion for conatruction. -3-

I have determined that the action being taken is appropriate when balanced against the availability of Trust Fund monies for use at other sites.

:NISTRATOR SUMMARY OF REMEDIAL ALTERNATIVE SELECTION

A. SITE LOCATION AND DESCRIPTION

The Army Creek Landfill formerly known as Che Llangollen Landfill, is located approximately two miles southwest of the city of New Castle, Delaware (Figure 1). The landfill is bordered to the north and west by tracks of the Penn Central Railroad and on the south and east by Army Creek. The highways adjacent to the Landfill are Routes 13 and 40 to the west and Route 9 to the east.

Llangollen Estates, a residential development is located 1/4 mile southwest of the site. The former Amoco Chemical Plant, closed in 1980 due to fire, is located 1/4 mile east of the site. Delaware Sand and Gravel, another landfill which has been placed on the Superfund National Priorities List, is adjacent to Army Creek Landfill and separated from it only by Army Creek, a tributary of the Delaware River.

The Army Creek Landfill, a former sand and gravel quarry is owned by New Castle County. The County operated this 44 acre landfill which accepted municipal wastes from 1960 until its closure in 1968. During that time, an estimated • 1.9 million cubic yards of refuse were landfilled at the site, 30 percent of which (or approximately 600,000 cubic yards) now lies below the seasonal high water table. In late 1971, water in a residential well southwest of the landfill developed quality problems, such as a distinctly disagreeable odor and permanent staining of porcelain fixtures. New Castle County and its consultant, Roy F. Weston, Inc., of West Chester, Pennsylvania, began a multi-year field investigation to assess the problem. Results from that investigation showed that leachate most likely originating from the Army Creek and Delaware Sand and Gravel Landfills, was contaminating local aquifers. Weston's remedial investigation lead to the installation of a groundwater recovery system designed to maintain a groundwater divide between the landfills and the Artesian Water Company Wellfield located downgradient of the landfills. Contaminated groundwater pumped from the recovery well system was discharged to Army Creek. In August 1984, EPA entered into a Consent Order with New Castle County to perform a Feasibility-Study (FS) at the site. B. SITE GEOLOGY The Army Creek Landfill is located within the Atlantic Coastal Plain physiographic province. The coastal plain is composed of a wedge-shaped body consisting of gravels, sands, silts and clays. The site-is underlain by two water-bearing formations, the Columbia and the Potomac. The Columbia, the upper-most aquifer beneath the landfill, is of

A Pi U U G 4 / 0 -2- . ui..,a (foG) Pleistocene Age and is from 10 to 60 feet thick at the site. This formation, which dips to the southeast, consists of medium to coarse grained sands, gravels, silts and clays which were deposited in shallow lens-shaped channels (Figure 2). The silt and clay units of the Columbia are discontinuous and do not form confining units.

The Potomac Formation of Cretaceous Age underlies the Columbia Formation and is generally separated from it by a confining clay layer at the site. The Potomac Formation dips to the southeast, is up to 600 feet thick and consists of silts and clays interbedded with sands and some gravel. The formation is divided into upper and lower units which are separated by a thick confining clay unit. The upper Potomac Formation silts and clays are discontinuous and non-uniform; in some places, the sands of the Columbia and Potomac are in contact.

C. Site Hydrogeology

Hydrologically, the Potomac upper clay functions as a confining zone for the underlying aquifer which is known as the upper Potomac Hydrologic zone. The direction of flow in the Potomac aquifer has been altered significantly over the past several decades due to withdrawal of water for industrial and domestic uses. The elevation of the potentiometric surface in the 1950's, before significant development of the aquifer, was about 6 meters below sea t level and flow direction was toward Delaware Bay to the southeast. In the 1960's, after wellfields were developed in the Potomac Formation for public water supplies and industrial use, the direction of flow remained to the south and east.

Artesian Water Company, a private water company servicing 5,000 customers in this area, completed its first well at the nearby Llangollen Wellfield in 1952. By 1961, shortly after the Army Creek Landfill opened, there were four operating wells withdrawing water from the Llangollen Wellfield at an annual average rate of about 1.42 mgd (million gallons per day). In early 1966, Artesian completed a new well and had increased its average pumpage to approximately 1.62 mgd. In 1969, a sixth well was added and the annual average pumpage from the Llangollen Wellfield increased to about 1.74(mgd). In late 1971 and early 1972, five more wells were added to Llangollen Wellfield. By late 1971, Artesian had increased its pumpage to an annual average of 2.60 mgd. Since then, Artesian Water Company has had to decrease pumpage to 2 mgd in order to slow down the migration of the contaminants and to avoid contributing to the problems of salt water intrusion that had become common in the area. There has been considerable litigation between Artesian Water Company and New Castle County, over groundwater use. The precise amount of water which Artesian had withdrawn In the past, or is presently entitled to withdraw is unclear.

Amoco Chemical Company initiated groundwater withdrawal from the Potomac aquifer in 1961 for use in their plant operations. Pumpage by Amoco was discontinued in 1980 when the plant closed due to fire.

It has been estimated that pumpage from the upper Potomac aquifer had

A R u u U k / D _3_ (fled) increased more than seven fold from 1952 to 1972 as a result of groundwater withdrawals from Artesian's Llangollen Wellfield and the Amoco Chemical Company plant wells. During this period, it has been reported that the increased pumpage caused the static water level in Artesian's Llangollen wells to decline up to 65 feet. Thia decrease in water level resulted in a steepening of the hydrologic gradient in the upper Potomac aquifer which accelerated the migration of pollutants from Army Creek and Delaware Sand and Gravel Landfills toward the Artesian and Amoco production wells. In late 1971, when one of the residential wells in the vicinity of the Army Creek Landfill, became contaminated with iron and other chemicals, New Castle County determined that the leachate generated by the landfill was contaminating the groundwater in the area. The leachate is produced by water entering the landfill in two ways: 1. Through direct precipitation on, and infiltration through, the landfill surface. 2. As groundwater moves laterally into the saturated lower portion of the landfill. Analysis of water inflow to the landfill is accomplished by dividing the landfill into two sections (Figure 3). Section 1, the western section (estimated area - 760,000 square feet), receives both surface water and groundwater inflow, and generally has a continuous clay floor of relatively low permeability. As a result, there exists a relatively thick zone of saturation in this portion of the landfill. Section 2, the older, eastern section of the landfill (estimated area =» 1,350,000 square feet), receives water primarily by infiltration of direct precipitation. In the vicinity of Section 2, the contact between the Columbia and the upper aquifer of the Potomac Formation is often a quite permeable zone. Here the Potomac clay deposits are relatively thin, sandy, or are absent. Consequently, water in the Columbia sands moves downward to the Potomac aquifer rather than laterally through the landfill. In addition, the Columbia sands have been excavated northeast and south of the landfill. Therefore, elevations at these points and in the marsh to the east are lower than those of the landfill surface and, in places, lower than much of the Army Creek Landfill floor. The surface of the landfill is pocketed with depressions resulting from the differential subsidence of the refuse. These depressions, coupled with the remaining flat surface of the landfill prevent stormwater from running off the landfill. The cover i~s generally silty, sandy and quite permeable. However, deposits of clay have accreted in the depressions so that stormwater forms ponds in the depressions. These ponds contribute to the slow infiltration of water into the landfill. Because of these surface conditions, it is estimated that at least 50 percent of the precipitation which falls directly onto the landfill surface infiltrates through the landfill cover and percolates through the refuse.

A R u u u ORIGINAL (Red)

D. SITE HISTORY

The Army Creek Landfill occupies an area that was formerly utilized as a sand and gravel pit. The gravel pit in which Army Creek Landfill was constructed, was excavated until a hard zone was encountered. This zone marks the base of the Columbia Formation and the top of the underlying clay.

In 1960, the landfill began operation as a municipal refuse landfill. The landfill was operated by New Castle County continuously until 1968 when it was filled to capacity. Refuse placement, compaction and covering operations at the Army Creek Landfill were carried out by the operators of the gravel pit under contract to New Castle County. Refuse burial began at the eastern end of the pit and generally continued toward the pit entrance on the west. The refuse was generally not well compacted and not regularly covered. The cover material used was obtained from the pit and includes residential sands, tailing piles and siltation basin deposits. As the operation progressed, cover material and landfill space became depleted. This encouraged deeper excavation which may have removed much of the clay layer which separated the Columbia from the Potomac formations. This in turn, could have created direct access routes for leachate to the Potomac from the Columbia. Direct access routes may also have occurred naturally due to the non-continuous geometry of the Potomac clay.

Improper covering, along with non-consistent compaction and decomposition ' of the waste materials, may have contributed to the differential settling of the waste material which has occurred since the landfill was closed.

In 1970, the landfill was covered with sandy material and the property was purchased by the County for use as a park. In late 1971, water in a residential well downgradient of the Army Creek Landfill Site developed severe quality problems. Evidence of these problems was the odor of the water and staining of the porcelain fixtures in the residence. In June 1972, New Castle County commenced a groundwater monitoring program which began with a well installation and sampling program. Monitoring by various agencies including EPA, United States Geological Survey, (USGS) New Castle County and the Delaware Department of Natural Resources and Environmental Control (DNREC) as well as the University of Illinois has continued up to the present. Monitoring has resulted in the identification of groundwater contaminants indicative of hazardous waste disposal as well as typical municipal refuse. It was also determined that the plume of these contaminants was moving towards the receptors located downgradient of the landfill. After considering alternative water supplies for the affected residents, New Castle County paid for an extension of Artesian's Water supply lines to the first contaminated residence and other homes along Grantham Lane. There was also a settlement with the homeowners to offset the monthly services costs.

In 1973, recovery wells RW-1, RW-2, RW-3, RW-4, RW-5, RW-6,27,28,29, 31 and 53 were installed in the upper Potomac Aquifer by Roy F. Weston under the direction of New Castle County (Figure 4). The purpose of the recovery wells was to intercept and contain the contaminant plume. The pumping of these wells created a groundwater divide between the Army Creek Landfill and the Artesian Water Company's Llangollen Wellfield. Beginning in 1977, the

A K u u u -5- ., ORIGINAL (Red) recovery wells showed a pattern of stability in water quality. In November 1977, New Castle County conducted a technical Round Table Conference in order to obtain input and opinions from nationally and internationally recognized authorities regarding the remediation of the contaminated groundwater in the vicinity of the landfill. As a result of the Technical Round Table Conference, a modified recovery system was installed in 1980, which included placement of new recovery wells closer to the landfill in order to pump more concentrated groundwater and therefore less clean water. The present recovery well system utilizes Wells 27, 28, 29, 31, RW-1, RW-9, RW-10, RW-11, RW-12, RW-13, and RW-14. US EPA has been involved at the site since 1974, when EPA representatives sampled the recovery wells for the first time. Since then, EPA has sampled the wells in 1977, 1978 and 1981 for priority pollutants. Based on the sampling analysis from the recovery and monitoring wells, the Army Creek Landfill site was proposed for the National Priorities List (NPL) in October of 1981 and was finalized on the list in September of 1983 due to extensive groundwater contamination. In August 1984, EPA entered into a Consent Agreement and Order with New Castle County to perform a Feasibility Study at the site. New Castle County submitted the final draft of the study in July 1986. ' E. CURRENT SITE STATUS Groundwater Since early 1972, intensive field studies have been conducted by the County, through its consultant Roy F. Weston, Inc., to evaluate the nature and the extent of the problem and to define and implement necessary controls to mitigate the groundwater contamination. These efforts included the installation and operation of the recovery wells in 1973, and monitoring and sampling of the recovery and monitoring wells. The analytical results from the various sampling efforts have demonstrated that the following organic constituents are present in the groundwater: benzene, 1,2,dichloropropane, nethylene chloride, 2,4,-dinitrotoluene, n-nltrosodimethy- lamine, 2,4,6-trlchlorophenol, bis(2chloroethyl)ether and chlorodibromomethane. These contaminants have been detected in concentrations above levels set in drinking water standards (Table 1). Inorganic contaminants were also found in water collected from monitoring and recovery wells. The contaminants include, beryllium, cadmium, chromium, lead, mercury, nickel, Iron and manganese in concentrations above the levels set in drinking water standards (Tables 2,3,4).

A R G G U k ; Surface Water

In 1981, the EPA field investigation team sampled Army Creek for priority pollutants. The data indicated the presence of organic and inorganic contaminants in the waters of Army Creek. Organics detected included phenol, bis(2- ethylhexyDphthalate, butyl benzylphthalate and di-n-butylphthalate (Table 5). Inorganics detected were aluminum, barium, cobalt, copper, iron, manganese, zinc, boron, calcium, magnesium and sodium (Table 6).

Additional water quality sampling for priority pollutant compounds was conducted by Weston for New Castle County in 1983 in connection with their NPDES permit application . Samples were analyzed by the New Castle County Laboratory. No volatile or extractable organic compounds were detected. The base/neutral organic compounds detected were bis(2-ethylhexyl) phthalate and di-n-butyl phthalate (Table 7). Upstream concentrations of both compounds were greater than downstream concentrations. All values were well below their respective ambient water quality criteria. Total metals were also analyzed in 1983. Of the metals analyzed from the water samples, cadmium, lead, mercury, nickel, and iron were found at higher concentrations upstream than downstream. Copper, silver, chromium, zinc, and manganese were found downstream at higher concentrations than upstream. Cadmium and mercury were the only parameters exceeding water quality criteria upstream and downstream of the pond (Table 8).

The State of Delaware, in connection with the remedial investigation at Delaware Sand and Gravel, conducted surface water sampling along Army Creek. No priority pollutants were found to exceed any water quality criteria.

Sediments

DNREC conducted sediment analysis in connection with the remedial investigation at Delaware Sand and Gravel (Table 9). Eight locations were sampled: six along Army Creek and Pond; one in a gravel pit pond as background and one at an intermittent stream east of Delaware Sand and Gravel. A comparison of this data with the clean stream sediments indicates that the Army Creek sample concentrations are considerably higher than those of the clean streams. Utilizing Station 7, the gravel pit pond for comparison and as a local background source, it is evident that samples taken from Army Creek and Pond have higher concentrations of all the metals detected. The iron and manganese concentrations in particular show an increasing trend in the downstream direction. Other metal concentrations peak at the pond entrance. Therefore, sediments have also been effected by the recovery well discharges.

Bioassays

Also in September 1973, a series of surface water and biotic surveys for Army Creek and Pond was initiated, to evaluate the affects of the recovery well discharges on the surface water system. Furthermore, in the past 13 years of discharges, Roy F. Weston, EPA and the State have taken numerous surface and sediment samples to determine if high levels of contaminants exist in the Army Creek and Pond and if so, what the affects of the contaminants have been. Overall, the results of the bioassays indicated that Array Creek and Pond were affected by the-recovery well discharges, although the impacts were not readily discernible. ORIGINAL -7- (Red)

In March 1986, U.S. EPA and Weston conducted split sampling for bioassay and macrobenthos evaluations. Also well discharges were collected and composited on a weighted basis from the existing recovery wells for use in the bioassays. Macrobenthos sampling results by the EPA and Weston were basically in agreement and concluded that the the low diversity of the pollution tolerant benthic species at all stations indicate degraded water quality within the watershed. The difference in diversity and composition of pollution tolerant species indicates that the macroinvertebrate community downstream of the pond is in better condition than the upstream station. The bioassays were conducted using fathead minnows and Ceriodaphnia dubia. It was determined by EPA that recovery wells 9,28,29 and 31 exhibited chronic toxicity, while recovery wells 10,11,12,13,14 and 27 exhibited no chronic toxlclty. DNREC is currently drafting a National Pollution Discharge Elimination System (NPDES) permit for the discharge of water from the County recovery wells to Army Creek. At thia point it seems likely that only water in the recovery wells exhibiting chronic toxicity (wells 9,28,29,31) will be required to be treated prior to discharge into Army Pond. Water from the wells which exhibit no chronic toxicity (wells 10,11,12,13,14,27) would be permitted to freely discharge into the pond. • A treatment alternative will not be chosen, at this time, because the final NPDES permit and its associated discharge limits has not been issued. In addition, the Delaware Sand and Gravel RI/FS has not been completed, therefore, we can not determine Delaware Sand and Gravel's contribution to the degradation of the groundwater, or the Army Creek and Pond at this time. It is our intention to combine the ultimate groundwater remedial actions at these two sites wherever possible. Also being deferred at this time is a decision on appropriate remedial measures for the sediments in Army Pond. Further analyses of the impacts on Army Pond is required to clarify what measures if any, are required. This Record of Decision specifically deals with the selection of the source control alternative to prevent the generation of the leachate that contaminates the local groundwater. We are deferring our decision on groundwater treatment alternatives until the RI/FS at Delaware Sand and Gravel is complete and the NPDES permit is Issued. Environmental Assessment The remedial investigations performed at the Army Creek Landfill Site revealed extensive groundwater contamination resulting from the generation of the leachate at the landfill. The groundwater and the surface water are contaminated with organic and inorganic priority pollutants, many of which exceed Water Quality Criteria for human health and aquatic life (Tables 1-4). The major public health concern at the site is the contamination of the upper Potomac and Columbia aquifers. The major user of groundwater in the area is the Artesian Water Company, located near Llangollen Estates. ~8~ (Red)'

In 1973, New Castle County installed its groundwater recovery system to prevent the migration of contaminated plume towards Artesian's Wellfield. Due to the success of the groundwater recovery system operated by the County, along with the reduction in pumpage by Artesian Water Company, the contaminants emanating from Army Creek Landfill are not currently threatening drinking water supplies.

Army Creek and Army Creek Pond receive surface water runoff and recovery well discharges from the groundwater recovery system. However, Army Creek and Pond is restricted for public use, prior to its discharge to the Delaware River, one mile downstream. The effect of the creek on the Delaware river is expected to minimize due to dilution.

Surface water bioassays have indicated that the surface water system has been effected by the recovery well discharges, although the severity of the impacts on the aquatic life is not readily discernible.

ALTERNATIVE EVALUATION

The major objective for the remedial action to be taken at the Army Creek Landfill Site is to minimize further groundwater contamination by reducing the leachate generated by the landfill. The requirements of CERCLA Section 104, of CERCLA 420 U.S.C. § 9604, EPA's mandate to protect the public health and welfare and the environment, determine the goals and levels of response for the site. '

In an effort to determine remedial alternatives for the subject site, feasible technologies were identified for consideration in a general response action table. Available technologies were then screened to eliminate all but the most definitive and feasible alternatives. This screening included: technical (site conditions or waste characteristics), environmental and public health, institutional, performance and cost criteria.

The technologies that have passed the technology screening process were examined further to identify remedial alternatives. Remedial alternatives were developed using best engineering judgment to select a technology or group of technologies that best addresses the problems existing at the site to protect public health, welfare and the environment. In an effort to provide a degree of flexibility in the final selection of a remedial action, alternatives covering a range of remedial action categories have been developed. These categories are described below:

1. No action: No-action alternatives could include monitoring activities.

2. Alternatives"that meet the CERCLA goals of preventing or minimizing present or future migration of hazardous substances and protecting human health and the environment, but which do not attain all of the applicable or relevant standards. (This category may include an alternative that closely approaches but does not meet, the level of protection by the applicable or relevant standards.) _9_ ORIGINAL (fad) 3. Alternatives that meet CERCLA goals and attain all applicable or relevant Federal public health and environmental standards, guidance, and advisories.

4. Alternatives that exceed all applicable or relevant Federal public health and environmental standards, guidance, and advisories.

5. Alternatives specifying offsite storage, destruction, treatment, or secure disposal of hazardous substances at a facility approved under the Resource Conservation and Recovery Act (RCRA). Such a facility must also be in compliance with all other applicable Environmental Protection Agency (EPA) standards. The broad evaluation criteria selected were: technical feasibility, public health, environmental, institutional evaluation, and cost effectiveness. Within those criteria the following factors were considered. - Technical Feasibility 'Performance olmplementability "Reliability

- Public Health Evaluation "Reduction of Health Impacts k - Environmental Evaluation "Reduction of environmental impacts "Protection of Natural Resources - Institutional Evaluation "Legal requirements, institutional requirements "Community Impacts - Cost Effectiveness "Capital Costs "Operation and Maintenance Costs "Present Worth Values "Sensitivity Analysis ANALYSIS OF REMEDIAL ALTERNATIVES Alternate Technologies Alternate technologies to recycle, destroy or treat* the wastes were screened for use at this site. These technologies included incineration of the waste, recirculatlon and/or treatment of the leachate, and block displacement which consists of sealing the sides and/or bottom of the landfill by grout injection technique.

These technologies were not chosen for several reasons. The discontinuous nature of the subsurface soil conditions argued against the technical feasibility of grouting the sides or bottom. -10- ORIGINAL (Red)

Direct leachate recirculation or treatment was evaluated on a pilot scale in the landfill but clogging of the wells and low permeability of the refuse in some areas prevented further consideration. Only incineration technology was retained for further evaluation.

Note: Capital, Operation and Maintenance, and Present Worth Costs for all alternatives are found in Table 10.

Alternative No. 1 - No Action with Monitoring

The purpose of presenting a No Action Alternative is to provide a basis for comparison of existing conditions with the other proposed remedial alternatives. Under the No Action Alternative, no additional remedial activities would be taken and any current activities would be terminated at the Army Creek Landfill site. This would mean that the present hydrologic divide between the groundwater contaminant plume and the Artesian Water Company Wells, maintained by the recovery well system, would be eliminated.

This alternative includes a. long-term monitoring program to provide information concerning contaminant presence and concentration. Groundwater monitoring would be performed between the landfill and the Artesian Water Company wells, and within the wellfield. i The primary public health concern of the No Action Alternative is the possible health risk resulting from the potential contamination of the downgradient production wells in the Artesian Water Company wellfield. Current production from these wells is approximately 2 million gallons a day (mgd), supplying the equivalent of 5,000 residences with drinking water. The effected population could increase, should the Artesian Llangollen Wellfield be shut down and the contaminants be drawn towards other wellfields in the area, including Artesian's Village, and Fairwinds wellfields located downgradient.

Of main concern is the attenuation of organic compounds found at concentrations exceeding drinking water criteria in nine of the twelve recovery wells. Table 1 lists the organic compounds found in the recovery wells, the maximum concentrations encountered, and the drinking water criteria. Under No Action, the contaminants would most likely be attenuated by dilution, dispersion and absorption prior to reaching a drinking water source. However, it is not known at what concentration these organics will persist in the groundwater. Therefore, a potential for human exposure by ingestion of organic compounds in concentrations above the drinking water criteria is associated with this alternative. This alternative would not provide protection to public health or the environment and contamination of groundwater through leaching of the contaminants would be expected to continue.

Common to All Other Alternatives

All of the source control alternatives discussed below would include a rigorous, initial, sampling and analysis program. Both monitoring and recovery wells would be sampled for Hazardous Substance List (HSL) compounds in order to more precisely define the contaminants and their concentrations. (Red)

All of the source control alternatives include downgradient recovery wells to control the migration of the contaminant plume. A treatment alternative for the recovery well discharges can not be addressed at this time. The State of Delaware is in the process of issuing an NPDES permit that would identify the safe and appropriate levels for contaminants at the point of discharge into the Army Creek and Pond. Based on those limits, the treatment alternative will be determined at a later date. A definite time period for phasing out the downgradient recovery well system cannot be established at this time for the following reasons:

0 Groundwater quality for organics at the site can not be precisely defined with existing data. 0 The total impact of the Delaware Sand and Gravel Landfill on the groundwater is not known at this time. 0 The remedial actions to be taken at the Delaware Sand and Gravel Landfill are not known. These actions may affect the quality of groundwater at the Army Creek site. The following methodology will be considered for phasing out the recovery well system: j The recovery well system will be evaluated in terms of both the flow system and water quality for a period of five years after the cap is installed or after the waste is excavated. If primary drinking water criteria levels are not met within this evaluation period, alternate concentration levels (ACL) will be considered. The ACLs will be based on an evaluation to define if sufficient attenuation will be achieved downgradient of the Army Creek Landfill, so that drinking water criteria levels will be met at any potential receptors. These ACLs will be applied at the recovery wells or the property boundary. When the ACLs are met, the recovery well system could be phased out. Alternatives that Include a cap may encroach on the 100 year floodplain at the south end of the site. The floodplain extends to approximately the ten foot contour. During design, detailed surveys and design evaluation will determine if any portion of the cap must extend to this area. Suitable measures including gabions or rip-rap may be used to protect the cap and minimize encroachment in the floodplain.

Alternative No. 2 - Downgradient Pumping Alternative No. 2 consists of a series of downgradient pumping wells to recover contaminated groundwater and control its migration. In 1972, when it was discovered that leachate had entered the underlying confined aquifer in the Potomac Formation and had contaminated a nearby domestic well, Weston was retained by New Castle County to investigate the extent of the problem and propose potential solutions. Preliminary hydrogeologic investigations conducted by Weston indicated that the leachate had contaminated a substantial volume of the upper Potomac aquifer and that contaminated groundwater was moving in the -12- direction of the Artesian Water Company's Llangollen Wellfield in response to both the natural groundwater gradient and the pumping effects of the Artesian wellfield. The nearest Artesian Water Company well was located about 1,600 feet from the edge of the contaminant plume.

Based on preliminary hydrogeologic investigations, a contaminant recovery and monitoring program was designed and Implemented in 1973 as an initial step towards an eventual solution to the problem. The recovery program was designed to achieve the following objectives:

0 To control the migration of contaminants towards Artesian Water Company's wells and to contain them in an area closer to the landfill.

0 To create a groundwater divide between the Artesian wellfield and the contaminated zone such that the groundwater flow in the contaminated zone could be reversed and the contaminated groundwater between the recovery wells and wellfield would move toward the Army Creek Landfill.

0 To redover contaminated water and restore the aquifer water quality.

0 To monitor the water quality and water levels in the area and evaluate the effectiveness of the recovery program.

0 To develop feasible leachate treatment and disposal methods until some type of permanent solution to the problem was determined.

As a result, a large number of observation and recovery wells was constructed. While the observation wells were constructed in both the shallow Columbia sediments and the underlying Potomac aquifer, the recovery wells were constructed only in the contaminated zone of the upper Potomac aquifer, which is the aquifer source used by Artesian.

The initial recovery well system consisted of eleven recovery wells RW-1, 2,3,4,5,6 and wells 27,28,29,31 and 53 (Figure 3). In 1977, the data collected during the initial operation from 1973 to 1977 was evaluated. The following conclusions were made at that time based on the evaluation:

0 The recovery wells have been successful in containment of the contaminated groundwater plume within the groundwater flow south of the Army Creek Landfill. 0 A groundwater divide has been developed between the Artesian Water Company's wellfield and the contaminated zone of groundwater. The groundwater flow in the contaminated zone between the landfill and the Artesian wellfields has been reversed towards the recovery wells and the Army Creek Landfill.

0 Recovery wells RW-1, RW-3, RW-4, and RW-5 continued to "pull back" the contaminants to as far as their present locations; these recovery wells could be phased out of the system in stages by reducing their pumping rates. -13- ORIGINAL (Red i 0 It would be necessary to monitor the water quality in the vicinity of recovery wells RW-1, RW-3, RW-4 and RW-5 more frequently than usual when their pumping rates have been reduced. This would assure early detection of any deterioration in water quality caused by reduced pumping rates.

0 It appears that most of the inorganic contaminants are discharged into the upper Potomac aquifer in an area of the landfill north of recovery wells 27, 28 and 29 and in the southwest corner of the landfill.

0 The total pumping rate of the recovery wells was approximately 1.5 million gallons per day, which is about 7.5 times more than the average daily rate of potential leachate production. Leachate would be recovered more

efficiently if the wells were located within and closer to the landfill.

0 Incrustation has caused a significant problem requiring frequent rehabilitation of the recovery wells. To control the incrustation problem, the pumping rates of the existing recovery wells should be further reduced by about 50 percent.

0 When RW-1, RW-3, RW-4 and RW-5 have been phased out of the recovery program, more recharge will be available for Artesian Water Company's wells.

It was therefore recommended that new wells RW-10, RW-11, RW-12, RW-13 and RW-14 be installed closer to the landfill such that leachate and contaminated groundwater could be recovered more efficiently. This was also recommended by the Round Table Conference in 1977.

In May 1982, the effectiveness of the modified downgradient pumping system was evaluated through a series of pump tests performed on the new recovery wells, RW-10, RW-11, RW-12, RW-13 and RW-14. The conclusions and recommendations generated as a result of the pump tests resulted in the phasing out of recovery wells RW-2, RW-3, RW-4, RW-5 and RW-6. The current downgradient pumping system includes RW-14, RW-13, RW-12,31,29,28,27, RW-1, RW-11, RW10, and RW-9 (Figure 3). The current system has maintained the groundwater divide necessary to intercept contaminated groundwater.

The clogging of well screens and discharge lines by iron precipitate is a continuous problem that is addressed through a regular program of well rehabilitation and pump repair. During the period of June 1982 through April 1983, at least one well was off-line for maintenance, repair or rehabilitation during any given month, with the exception of June 1982'. Since the phasing out of wells with the porest performance, a biannual maintenance program has been established to treat and rehabilitate the twelve operating wells. Maintenance and replacement of parts have been performed as part of the maintenance program.

Since the recovery well system is already in place and operative, there is no implementation time necessary for this alternative.

A K U U U 4 U / ORIGINAL -14- (Red)

Sampling and testing performed at the Artesian Water Company's wellfield and concentration gradient maps of the area have indicated that the downgradient pumping system along with controlled withdrawal by Artesian has been effective in containing the contaminated groundwater plume through the creation of a hydrologic divide between the landfill and the Artesian Water Company's wellfield. Alternative 2 has therefore been proven to have contained contaminated ground- water. By controlling the contaminated groundwater the pumping system has prevented the possible abandonment of the upper Potomac aquifer as a source of water supply in the production wellfields near the landfill and reduced the public health risk that could have resulted if the contaminated groundwater plume was not controlled.

Alternative 2 does not, however, address the source of leachate entering the Potomac aquifer or the pathways through which water enters the landfill resulting in leachate production. Precipitation infiltrating through the landfill surface and groundwater infiltration through the northwest side of the landfill from the Columbia aquifer will continue under this alternative. Therefore, leachate migration into the Columbia and upper Potomac aquifer will continue should Alternative 2 be implemented.

This alternative does not attain all applicable and relevant public health and environmental standards as defined by CERCLA and RCRA.

Alternative No. 3 - Downgradient Pumping and Landfill Capping

Alternative 3 consists of the downgradient pumping program evaluated under Alternative 2, and includes capping the landfill with a multi-layered cap.

The multi-layer cap system represents a recently developed cover technology that is gaining widespread use as an infiltration control strategy for waste containment or in-place closure. The multi-layer cap system performs the basic functions of minimizing infiltration into the waste site; directing and transmitting percolation and gas migration away from the site; and providing a final cover for the site and growth medium for vegetation. A typical multi- layer cap system, as shown on Figure 5, consists of the following three layers:

a) Uppersoil layer. A top soil and native soil layer, typically placed to a depth of about 12-24 inches. This layer serves to support vegetation, provide a cover for the drain layer, and divert surface runoff.

b) Middle drain layer. A graded layer of porous flow zone material (e.g., sand, gravel, geogrid) to act as a drainage medium. This layer is typically placed to a depth of about 18 inches.

c) Cap layer. A compacted layer of fine-grained soils of low permeability designed to divert infiltration that has percolated through the upper soil layer. This cap layer is typically placed to depths of about 18- 24 inches.

The successful multi-layer cap system Incorporates the use of low permeability materials to provide a surface seal over the contaminated area. A zone of high -is- ORIGINAL permeability materials, such as graded gravel, aggregate, and drainage geotextiles, is typically placed over a cap layer to enhance lateral movement of water that percolates through the upper soil layer. The upper soil layer provides the following: (a) A soil cover to promote runoff. (b) A protective cover for the drain layer. (c) A medium for growth of vegetative cover. The vegetation not only stabilizes the cover system from possible damage due to water or wind erosion, but also contributes to moisture loss through evapotranspiration . Several major advantages of the multi-layer cover system as compared to a standard native soil cover include the following: (a) A protective soil layer is placed over the cap layer; the cap is not directly exposed to excessive damage due to weathering, cracking or root penetration. (b) A drain layer serves to divert additional percolating water so it does not eventually migrate into the underlying waste material. ' (c) Possible slumping of the topsoil and upper soil layers is minimized. Calculations using hydrologic simulation modeling show that the multi- layered cover system can divert greater than 90 percent of the precipitation falling on the site. Since the cover is constructed of natural materials, it is expected to remain effective over the 30-year evaluation period. Final design studies will be used to determine the material types and specifications for the number of layers and thickness of the final cap system. Any system installed will comply with the RCRA cap requirements.

Alternative 3 provides the same health benefits as Alternative 2 by containing the contaminant plume through the creation of a hydrologic divide between the landfill and the Artesian Water Company's wellfield by downgradient pumping. The recovery pumping program in place at the Army Creek Landfill has proven to have contained contaminated groundwater close to the landfill. By controlling the contaminant plume, the pumping system has prevented the possible abandonment of the upper Potomac aquifer as a source of water supply in the production wellfields near the landfill. This alternative attains all applicable and relevant public health and environmental standards as defined by CERCLA and RCRA. Alternative No. 4 - Downgradient Pumping, Landfill Capping, and Upgradient Controls A. Non-phased Approach - The non-phased approach to Alternative 4 would include the continuation of the downgradient pumping program and the simultaneous -16- ORDINAL "?.?d) construction of the final cap system and the upgradient groundwater controls (Figure 6). This approach to Alternative 4 provides additional immediate measures to further mitigate the environmental impacts of the landfill as compared to Alternative 3. The upgradient controls would intercept and significantly reduce the groundwater entering the landfill along the north- western side, thus reducing the potential volume of leachate produced. The flow of groundwater into the landfill along the northwestern side has been estimated at 25,000 gpd as compared to 4,000 gpd of precipitation infiltration.

B. Phased Approach - The phased approach to Alternative 4 involves two phases. Phase 1 would include installation of the final cap system with continuation of the downgradient pumping system. The effect on the groundwater quality as a result of capping the landfill would then be monitored and assessed prior to initiating Phase 2 upgradient controls. It is possible that although a significantly greater volume of groundwater passes through the site than does precipitation, the refuse that comes in contact with the groundwater has already had much of the contamination leached after almost seventeen years in a saturated state. Monitoring has also shown that the groundwater table elevations have dropped over the past twelve years due to the additional pumping, resulting in a lesser quantity of refuse that is saturated. Precipitation, on the other hand, percolates through the entire refuse stratum, allowing for more contact with a greater volume of ' landfill material. Following an evaluation period of 5 years after the cap is installed, the need for upgradient groundwater controls to reduce leachate production would be determined. This determination would be based on the evaluation of the monitoring well water levels, pumping rates and water quality.

Both the phased and non-phased approaches include surface management measures and gas venting as part of the construction of the cap system.

The technical evaluation of the downgradient pumping program has been performed under Alternative 2, and the evaluation of the multi-layer cap system under Alternative 3. Final design analysis will be used to determine the material types and specifications for the number of layers and thickness of the final cap system. The analysis for this alternative will therefore concentrate on evaluating the upgradient controls. An upgradient pumping network is used here for evaluation purposes only. The final upgradient control (pumping or trench) would be determined during the design phase. It is anticipated that less pumping, both in quantity and duration, by the downgradient recovery well system would be required as a result of capping the landfill. Upgradient controls should further hasten groundwater cleansing, reducing the time the downgradient system has to be operated.

The arrangement and number of recovery wells necessary to prevent the lateral inflow of groundwater into the Army Creek Landfill would be contingent upon several of the following factors; the volume of inflowing water, the depth to which the water table must be lowered, and the ability of the Columbia aquifer to transmit water. ORIGINAL -17- (Red)

To intercept the inflowing groundwater and lower the water table within the landfill, Weston determined that five recovery wells, spaced at 320-foot intervals, would be needed. The wells could be located directly south of the railroad tracks along the northwestern boundary of the landfill (Figure 3). To ensure maximum drainage from the Columbia aquifer, the depth of the wells should extend to the base of the aquifer (25 to 30 feet). An evaluation of various pumping rates estimated that a discharge rate of 20 gpm per well would provide maximum drainage of the Columbia aquifer without exceeding the critical well drawdown limits. The pumping rate of 20 gallons per minute(gpm) at each of the five wells would remove approximately 144,000 gpd of groundwater, creating a hydrologic drain for the groundwater enroute to the landfill. The drawdown influence from the pumping wells would lower the water table within the refuse. Upgradient pumping would essentially dewater a major portion of the refuse, leaving only a fraction of the total waste volume saturated near the base of the Columbia Formation. The water level in Army Creek could potentially impact the dewatering influences of the upgradient wells. If the cumulative drawdowns from the five recovery wells lowers the water table below the water level of Army Creek, then surface water flow into the Columbia aquifer could be induced. This would eventually create a steady-state condition between the water levels in the wells and the stage of the stream. At this time, the variation in the elevation of the surface water in Army Creek is unknown, and the effect of the stream on the maximum water table drawdowns cannot be determined. Alternative 4 provides the same health benefits as Alternatives 2 and 3 by containing the contaminant plume through the creation of a hydrologic divide between the landfill and the Artesian Water Company's wellfield by downgradient pumping. Alternative 4 provides further measures to mitigate the environmental impacts remaining after the implementation of the downgradient pumping and landfill capping included in Alternative 3. Under the non-phased approach to Alternative 4, upgradient controls will be installed at the same time the landfill is capped. Both pathways of infiltration into the landfill would, therefore, immediately be addressed. Potential leachate production should be significantly reduced as a result of these actions. It is therefore anticipated that groundwater cleansing would be further hastened under Alternative 4. The phased approach would allow for a period of monitoring and assessment of the effectiveness of capping the landfill on groundwater quality. Following an evaluation period of 5 years after the cap is installed, the need for additional measures to reduce leachate production would be determined. This decision would be based on an evaluation of water levels and water quality at the Army Creek Landfill. This alternative attains all applicable and relevant public health and environmental standards as defined by CERCLA and RCRA.

Alternative 5 - Downgradient Pumping, Partial Removal and Landfill Capping Alternative 5 consists of the downgradient recovery well system also included ORIGINAL -is- (Red)

in Alternatives 3 and 4, the excavation of the landfill refuse in the western section, and movement of the excavated refuse on the eastern section. The eastern section would then be graded and capped with a multi-layered cap system, and the western section backfilled with clean fill material, graded to drain surface run-off and vegetated. Erosion and run-off controls would be established in excavated and fill areas. The saturated refuse in the western section would require "dewatering" or draining as it is excavated and would be mixed with dryer refuse to be placed and compacted on the eastern section of the landfill. A combination of draining/pumping of free liquids from the saturated refuse and upgradient controls would be required for the dewatering process. Figure 7 provides a graphical presentation of Alternative 5.

This alternative will remove one of the sources of contamination of the Columbia aquifer and subsequently the upper Potomac aquifer by the excavation of the western section of the landfill. Field information suggests that groundwater is infiltrating the refuse laterally in this section of the landfill.

This alternative also addresses the precipitation infiltration through the removal and redeposition of refuse to the eastern section of the landfill which would then be capped with a multi-layered cap system. The multi-layered cap system was evaluated in Alternative 3. Alternative 5 would be effective in addressing the pathways of infiltration and reducing the potential volume of leachate produced from an estimated 29,000 gpd (25,000 gpd groundwater infiltration • plus 4,000 gal/day of precipitation infiltration) to an estimated 200 gpd (precipitation infiltration through multi-layered cap system). Source removal would provide an effective long-term solution to groundwater contamination at the site. The useful life of the multi-layered cap system would depend on the establishment of a maintenance program that would maintain a proper vegetated cover and integrity of the cap. A properly constructed and maintained cap should last through the 30-year evaluation period.

Once the vegetation on the multi-layered cap system is established it would require routine regular maintenance. The entire vegetated area should be mowed once or twice a year to minimize the potential for growth of deep-rooted vegetation. The surface cap on the eastern section should be periodically inspected to assure continued integrity of the capping system. Cracking, erosion damage, and differential settlement damage would require repairs.

Two of the major concerns resulting from the excavation of the western section of the existing landfill include the following:

0 Dewatering of the western section would be required before the saturated refuse is excavated from below the water table. Upgradient controls similar to the system outlined under Alternative 4 can be used to lower the water table below the refuse. Complete dewatering may include the construction of drains and sump controls, but it is anticipated that most of the free liquid would be removed by the upgradient controls. The discharge from the upgradient controls could possibly require treatment. Since the duration of pumping (if used) will be short-term (time required to excavate the western section), the most cost effective treatment -19- ORIGINAL <^4) option could possibly be discharge to the local waste treatment facility (Wilmington Waste Water Treatment Plant).

0 A potential slope stability problem could result between the eastern section and the western section as excavation of the western section resulted in deep cuts into landfill refuse. The excavation should proceed in an "area" type manner to minimize deep cuts and possible stability problems. Final side shapes after backfilling in the eastern section should be limited to a maximum ratio of 3 horizontal to 1 vertical (3:1) to ensure slope stability.

Excavation of the saturated refuse would be accomplished using either backhoes or draglines working from the top of the working face. If a pocket of non- refuse or potentially hazardous wastes has been identified, special excavation and handling procedures would be initiated.

All of the refuse, with the possible exception of waste requiring special handling, would be loaded onto dump trucks. These vehicles could then haul the refuse on a temporary access road along the north side of the landfill running parallel to the existing railroad. Free liquid from the transportation of the refuse would therefore be contained within the existing landfill area. Extensive odor control would be necessary within and around the perimeter of the excavation site for the dump trucks. s,

After the western section had' been completely excavated and backfilled with a clean soil fill, the eastern section would be prepared for the final capping. The cap would be placed over the intermediate soil cover and utilize a multi-layer design. The multi-layer cap system would significantly reduce precipitation infiltration. Erosion and sedimentation controls would be initiated until a proper vegetated cover is established. Gas venting and surface management measures will be installed during the construction of the cap system.

While Alternative No. 5 represents a potential safety risk to the construction workers, due to the unknown types of wastes and conditions which would be encountered during excavation, proper safety protocol would reduce the risk.

Alternative 5 provides the same health benefits as Alternatives 2, 3, and 4 by containing the contaminant plume through the creation of a hydrologic divide between the landfill and the Artesian Water Company's wellfield by the existing downgradient pumping program. Alternative 5 provides basically the same environmental benefits as Alternative 4 but addresses the groundwater infiltration condition in the western portion of the landfill by eliminating the source of leachate generation through total removal of the refuse in the western section. Groundwater cleansing would be hastened by the elimination of the source of contamination. Capping the eastern section with a multi-layer cap would signifi- cantly reduce precipitation infiltration which would further hasten groundwater cleansing.

During excavation, odor and vector problems would likely occur in addition to the need to handle draining water from saturated refuse. Leachate pumped during dewatering operations before the saturated refuse is excavated would need to be collected and treated.

Art u u -20- ORIGINAL This alternative attains all applicable and relevant public health and '•Hed) environmental standards as defined by CERCLA and RCRA.

Alternative 6 - On-site Incineration and Downgradient Pumping

This alternative consists of the construction of an incinerator and power generator facility adjacent to the subject site, excavating and incinerating the waste, and backfilling the ash residue on-site. In order for this alternative to be feasible, the excavated landfill wastes at the site would need to be mixed with raw-solid waste from nearby communities or other fuel to produce a combustible mixture. Otherwise, the fuel requirements for burning the wet waste would be very excessive. Excavation of the saturated material would require dewatering. This could be achieved by upgradient pumping or pumping directly from the excavated area. The discharge from the dewatering operation could require treatment.

This alternative would include continued downgradient pumping to assure that contaminated groundwater did not reach the Artesian Water Company's wellfield. A long-term groundwater monitoring program would determine when the downgradient recovery system could phased out after the landfill had been removed and incinerated.

Alternative 6 would provides basically the same public health and environmental benefits as Alternatives 4 and 5 through downgradient pumping and removal of the source by excavation and incineration. Dry refuse or other fuel would need to be transported to the site and mixed with the saturated waste to make it burnable. Air pollution control devices required under RCRA would reduce the release of contaminants into the air. Incinerator ash and residue would be backfilled on-site only in areas above the groundwater table and eventually capped. Dust, odor and drainage of liquids from the saturated waste are problems associated with the excavation of landfill refuse. Other environmental and health concerns would be associated with the transport of dry refuse to the Army Creek Landfill site. These concerns include noise and dust from transportation and vector problems. Measures such as vector control and site access routing, would be initiated to mitigate these problems. Construction activities during excavation could affect wetlands habitats through noise, surface water diversion practices and dust. Drainage could also have an effect, if not controlled. On-site incineration would be required to meet the technical requirements of RCRA. In addition to RCRA requirements, the remedy would need to comply with other applicable State and Federal requirements but would not need a permit. A monitoring program would also be a mandatory part of the incineration process. Significant public opposition could be expected to this alternative.

This alternative attains and/or exceeds applicable and relevant public health and environmental standards as defined by CERCLA and RCRA.

Alternative 7 - Off-site Disposal by Landfilling at an Approved Site and Downgradient Pumping This alternative consists of completely removing the landfilled waste by -21- standard excavation methods and disposing of the waste in an approved off-site facility. Upgradient pumping has also been included for the anticipated dewatering of the saturated material in the bottom of the western part of the landfill prior to excavation. The landfill area would be backfilled, following complete excavation of the waste material. This alternative would eliminate a source of leachate generation (refuse) and thus eliminate the addition of contaminants to the groundwater.

This alternative includes a downgradient pumping program. Monitoring of the recovery system will determine when the system can be phased out after complete removal of the landfilled wastes. Alternative 7 would provide basically the same public health and environmental benefits as Alternatives 4, 5, and 6 through downgradient pumping and the complete removal of the source of contamination by excavation and disposal in an approved off-site landfill facility. These actions would prevent direct human exposure and accelerate groundwater cleansing as do Alternatives 4, 5, and 6. Dust, odor, and noise problems would arise from the excavation and hauling actions contained in this alternative. The off-site facility would need to be a RCRA permitted landfill to assure that potential environmental impacts at the new site are minimized. Commercial disposal facilities must meet stringent analytical, RCRA, and • State permitting and compliance standards. Using off-site facilities also would require that the Department of Transportation requirements are met. Opposition could occur from the State receiving this large quantity of waste (approximately 2,000,000 cubic yards). Off-site facilities could also be reluctant to accept this large quantity of waste. This alternative attains and/or exceeds all applicable and relevant public health and environmental standards as defined by CERCLA and RCRA. RECOMMENDED ACTION (Table 10)

Section 300.68 (j) of the National Contingency Plan (NCP) states that the appropriate extent of remedy shall be determined by the lead agency's selection of the remedial alternative which the agency determines is cost-effective (i.e., the lowest cost alternative that is technologically feasible and reliable) and which effectively mitigates and minimizes damage to, and provides adequate protection of public health, welfare, or the environment. Based on our evaluation of the cost effectiveness of each of the proposed alternatives, of the comments received from the public, and information received from the Delaware Department of Natural Resources and Environmental Control, we recommend that the phased approach Alternative 4B be implemented at the Army Creek Landfill Site.

This alternative Includes downgradient pumping with monitoring, landfill capping and possibly upgradient controls. This alternative will reduce the public health risk by possibly containing the contaminant plume through the downgradient recovery system. This alternative will also control precipitation infiltration through the landfill surface with a multi-layered cap. Groundwater infiltration through the northwest side of the landfill from the Columbia

j21 ft U G U H 'J 22 - ORIGINAL (Red) aquifer will be controlled by upgradient measures; if necessary. Leachate migration into the Columbia and upper Potomac aquifers will be reduced. The upgradient controls (pumping or an interception trench) may be installed following an evaluation period of up to 5 years after the cap is installed. This decision would be based on an evaluation of water levels and water quality at the Army Creek Landfill. An additional component of this alternative is a well monitoring program.

At this time, the selection of a groundwater treatment alternative has not been made and will be the subject of a future decision document. In particular this decision has been delayed because the final NPDES permit has not been issued and the Delaware Sand and Gravel RI/FS has not been completed. It is EPA's intention to combine the remedial actions at both sites where possible and cost-effective. Also being deferred at this time is a decision on appropriate remedial measures for sediments in Army Pond, that decision will be made at the same time as groundwater treatment is considered and after further analysis is accomplished regarding the actual impacts on Army Pond.

Operation and Maintenance

At least, quarterly inspection and maintenance will be required during the operation of the downgradient and upgradient controls. Wells will be inspected and maintained to insure their continual functioning. !

Maintenance of the multi-layered cap will be required to ensure that the cap is functioning properly in preventing the infiltration of stormwater into the landfill. Vegetation loss, erosion, cracking or other cap disturbances will be corrected.

Consistency with Other Environmental Laws

Alternatives were examined in light of relevant Federal, state and local environmental program requirements and in light of all RCRA and CERCLA require- ments for the closure of hazardous waste landfills and for disposal of excavated contaminants in offsite hazardous waste facilities, including landfills and incinerators. The recommended action meets all applicable and relevant public health and standards as defined by RCRA and CERCLA.

Evaluation of Alternatives Not Selected (Table 11)

The No-Action Alternative No. 1 with monitoring was not selected since it would not control the source of contamination and would allow further degradation of groundwater. Implementation of the No-Action alternative would mean that the present hydrologic divide between the Army Creek Landfill site and Artesian Water Company's production wells would no longer exist. Therefore, a potential for human exposure by ingestion of organic and inorganic compounds in concentrations above the drinking water criteria would exist. This alternative does not provide protection to public health and the environment. -23- *, ORIGINAL (Red) Alternative No. 2 involves downgradient pumping with monitoring. Although this alternative would reduce the public health risk by containing the contaminant plume through pumping, it would not, however, address the source of leachate entering the Potomac aquifer or the pathways in which water enters the landfill resulting in leachate production. Precipitation infiltration though the landfill surface and groundwater infiltration through the northwest side of the landfill from the Columbia aquifer would continue under this alternative. Therefore, leachate migration into the Columbia and upper Potomac aquifers would continue for Alternative No. 2. Alternative No. 3 would involve downgradient pumping with monitoring and landfill capping. Although this alternative would reduce the public health risk by containing the contaminant plume through pumping and control precipitation infiltration through the landfill surface, it would not address groundwater infiltration through the northwest side of the landfill from the Columbia aquifer. Therefore, leachate migration into the Columbia and upper Potomac aquifers would continue for Alternative No. 3. Alternative No. 5 would involve excavation of the landfill refuse in the western section, and disposal of the refuse on the eastern section, downgradient pumping with monitoring and capping. Alternative No. 5 would address the groundwater infiltration condition in the western portion by eliminating the source of leachate generation through total removal of the refuse in the western section of the landfill. This alternative was rejected because it provides the same benefits as Alternative No. 4, but costs twice as much ($37,930,000 vs. $15,290,000), and would be more difficult to implement. Alternative 6 would involve on-site incineration and downgradient pumping. This alternative would provide basically the same public health and environmental benefits as Alternative 4 through downgradient pumping and removal of the source by excavations and incineration. This alternative was rejected because it would provides the same benefits as Alternative No. 4, but would cost 7 times ($108 million vs. $15,290,000) as much and would be more difficult to implement. Alternative 7 would involve the complete removal of the landfill and down- gradient pumping and monitoring. This alternative would provide basically the same public health and environmental benefits as Alternative 4 through down- gradient pumping and removal of the source. This alternative was rejected, because it would provides the same benefits as Alternative 4, but costs 15 times as much ($243,000,000 vs. $15,290,000) and would be more difficult to implement. (Red)

ENFORCEMENT CONFIDENTIAL

ENFORCEMENT SUMMARY AND CURRENT STATUS

Summary

The Army Creek Landfill Site, located in New Castle County, Delaware, was owned and operated by New Castle County as a municipal landfill from 1960 to 1968. At that time, the landfill reached its capacity and the County began operating a municipal landfill at Tybouts Corner. Many of the generators who disposed of waste in Army Creek Landfill began using Tybouts Corner when Army Creek closed in 1968. Information gained through the investigation of Tybouts generators has been applied toward developing a list of waste generators who used Army Creek Landfill for waste disposal.

EPA issued a CERCLA Section 104(e) letter to New Castle County, operator and owner of the Army Creek Landfill, in January of 1983. In later negotiations, the County indicated a willingness to conduct a Feasibility Study at the site. EPA and New Castle County signed a Consent Agreement on August 1, 1984 for the ; County to conduct a Feasibility Study at the site. EPA issued twenty § 104(e) letters in January of 1983 and eight in May of 1983. EPA has also gained information about generator input to Army Creek Landfill from discovery documents prepared by ICI Americas in anticipation of litigation concerning Tybouts Corner Landfill and from a PRP search document prepared by EPA contractor, Techlaw. EPA later issued 34 additional § 104(e) letters.

Besides New Castle County, EPA identified and sent notice letters to 18 additional Potentially Responsible Parties (PRPs) in July of 1986. The PRPs were notified of their responsibility for site contamination at Army Creek and were instructed to enter into negotiations with the Agency to conduct remedial activities at the site. Identified PRPs include:

Chrysler Corporation Twardus and Sons Gates Engineering Company, Inc. Stauffer Chemical Company Allied Corporation NVF Company Atlantic Aviation Corporation E.I. duPont de Nemours and Co., Inc. Avon Products ICI Americas Budd Company Ametek, Inc. General Motors Corporation Hercules, Inc. Materials Transit, Inc. FMC Corporation Landfill, Inc. New Castle County Mr. Edgar T. Harvey In addition the State of Delaware technically holds title to the property upon which the Army Creek Landfill is located. EPA has made a determination at this time not to consider the State as a PRP due to their lack of involvement with operations at the site. -2- Oii...,,., (Red)

Current Status

A meeting with the PRPs was conducted on August 28, 1986 at EPA Region III offices. In attendance were Region III technical and legal staff as well as representatives of the State of Delaware, Allied Corporation, ICI Americas, Avon Products, Budd Company, E.I. duPont de Nemours and Company, Inc., Hercules, Inc., General Motors Corporation, Cheseborough Ponds, Gates Engineering Company, Inc., and New Castle County.

The contractor for New Castle County who prepared the Feasibility Study discussed the recommended alternative for remedy of the threat of contamination posed by Army Creek Landfill. EPA technical staff discussed the rationale for choosing this alternative and EPA legal staff outlined EPA's options as far as future enforcement actions were concerned.

The PRPs agreed to respond to notice letters by mid-October, 1986. Three options are open to EPA at this point. The Agency can reach a Consent Agreement with the PRPs, EPA can issue a Unilateral Order or EPA can conduct a Fund financed cleanup and later sue to recover costs from the PRPs.

EPA is planning to pursue negotiations with the PRPs to reach an agreement for the PRPs to fund a Remedial Design and Remedial Action at the Army Creek site. If negotiations are unsuccessful EPA will pursue the options mentioned 1 above to complete remedial activities at the Army Creek site.

H R U U U WILMINGTON

ARMY CREEK ARMY (LLANGOLLEN WARE LANDFILL LANDFILL

CO CHEMICAL CORP POLYMER PLANT

ARTESIAN WATER CO. WELL FIELD

3ASC MA» IS A PORTION OF TX Ulfl* WUSMQION SOUTH, OCL.-N.J. FIGURE V QUAOMAN8L2 (7.9 MMJTE SEMES, IM7) COMTOUft INTERVAL » 10' LOCATION OP ARMY CREEK LANDFILL NEW CASTLE COUNTY. DELAWARE ._, SCALE'• I "=2000' " MKu CORPORATOR LIQUID WASTE DISPOSAL PIT

4O

DELAWARE: 20 SAND 6 GRAVEL

COLUMBIA FORMATION APPROXIMATE WATER TA_LE --20 IN 1961

--4Q

r—60

:; : . •'•^'_-ze«4^*?-^'."-^ ^^ ^T- » w^i _^« .^^h^» "^ia^'V^upPE_**CT -,••*.? *UPPE^ » ^B*R* POTOMAC FORMATION^ --80

-100

UJ --I20

--I40 c •>. CD LEGEND SOURCE •• C K. LEE , JUNE , 1962 CM C HYDRQGEQLOGIC SECTION A-A SANO WITH CLAY ARMY CREEK LANDFILL NEW CASTLE COUNTY. PEL Kj CLAV WITH SAND HORIZONTAL SCALE: |"»500' IMUS NOT TO VERTICAL SCALE a LANDFILL JcaFFORATIOr DELAWARE SAND A 6RAVEL LANDFILL A

AMQOO CHEM CORK YMERPLANT ' •,*.

X" PJ C ' c cr» en c

ARTESIAN WATER CO WELL FIELD

LEGEND J> INDICATES LOQATCN OF ^ RECOVERY WELL ARMY CREEK LANDFILL- SITE SKETCH —^indicates groundwater I I flow direction NEW CASTLE COUNTY. DELAWARE SCALED i"= 1000' ' IMUS CQRPORATGN LEGEND INDICATES LOCATION OF RECOVERY WELL INDICATES LOCATION OF POTOMAC WELLS (DEEP) • BIS- INDICATES LOCATION OF COLOMBIA WELLS (SHALLOW

DELAWARE BAND a ORAVEL O LANDFU. A

AMOCO CHEMCORR PLANT

ARTESIAN WATER CO WELL FIELD

•n ARMY CREEK LANDFILL - NEW CASTLE COUNTY, DELAWARE 5 c 30 LOCATION OF MONITORING, PRODUCTION AND RECOVERY WELLS m SCALE : |"= 1000 NUS CORPORATION * ^w^SA'-S^ , ORIGINAL TABLE 1 (Red)

ORGANIC COMPOUNDS IN RECOVERY WELLS EXCEEDING DRINKING WATER CRITERIA*

Max. Cone. Criteria Well Parameter (ug/1) Tug/I) RW-1 Ben-zene 12.0 5.0ft 1 , 2-dichloropropane 40.6 6.0b Methylene Chloride 32.0 0.19C RW-10 2 , 4-dinitrotoluene 44.0 O.lld , N-ni tr osodimethy lami ne <10.0 0.0014° 1 , 2-dichloroethane 51.0 5.0a RW-11 Benzene <10.0 5.0a RW-12 Benzene 10.3 1 , 2-dichloropropane 25.1 6iob Methylene Chloride 21.2 0.19C 2 , 4, 6-trichlorophenol 3.0 1.8% Bis^ 2-chloroethyl ) ether <10.0 6.03d RW-13 1 , 2-dichloropropane 26.8 Methylene Chloride 21.3 Bix ( 2-chloroethyl ) ether 46.0 O.*03d Benzene 37.0 5.0a RW-14 Bis ( 2-chloroethyl ) ether <10.0 0.03d 2 , 4-dinitrotol uene 38.0 O.lld 28 Benzene 40.0 5.0a 29 Benzene 45.0 5.0a

31 Benzene 150.0 5.0% Methylene Chloride 16.3 0.19C Chlorodi br omomethane 19.2 0.19^ 2 , 4-dinitrotol uene 116.0 O.lld

* - All laboratories (1983-1985) a » Proposed Primary MCL (EPA, 13 November 1985) b * Proposed RMCL (EPA, 13 November 1985) c « Water Quality Criteria for Human Health (Fish and DrinJcing Water); concentration of total halomethanes (CWA) d * Water Quality Criteria for Human Health - Fish and Drinking Water (CWA) e Water Quality Criteria for Human Health - Adjusted for DrinJcing Water (CWA) . . ." TABLE 2

t""V ^«.--A l^ii.11 ill

Cioutl Wjt.ii Quality 1941*

I'XI WL.-| 1 34 VLil 1 ^6 1)11 ilk in

AJit ii <0.010

<0.002

Boiyll iiiui ,0.0001 <0.000i

O.OU06 0.001 0.0006 0.0015 O.OIOb

0.0216 0.0151 0.0116 0.028U 0.050b

0.0048 0.0111 0.0012 0.0104 l.)(

0.0101 O.OU8V 0.0068 0.0061 0.050b

K:l .JUI y 0.00/2 0.0006 0.0002 0 . 000 1 0 . 00 1

Nickel 0.050 0.070 0.060 0.050 O.OI54C

<0.050 <0.050 <0.050 <0.050 O.OIOb

Silver <0.000i <0.0005 ;-

•I1i4lliu <0.002

Zliic O.OM O.OM 0.0)0 0.050 5.0d

e U J4I 2.540 0.220 1.160 ).650 O.J

0.160 0.060 0.040 O.OUO 0.051^

iul lr Quality Criterid - Oru^iioltlc - Flail «Kl Drinking Mttjr (OKI c •i - S>:mkJary H.'l. c:> ( •= Pr c ex C'; TABLE 3

MUtt CHEtX IANOF1U. t*M LASTLY, (Kl AWAKE

WtU, INLHGANIC WMtX QUALITY 1481*

Total Con- oentritioii W..I :r (PJ/|> HH-1 HM-) HM-4 HH-6 HM-9 KM 10 KM-11 RW-12 HW 11 KM 14 27 28 29 Jl Cr iteila I'l iterid

Aiitiiooiiy <0.00l <0. 001 CO. 001 CO. 001 CO. 005 CO. 001 CO. 001 0.0064 CO. 001 0.0048 CO. 001 0.0061 <0.005 CO.001 0. 1.6"

Ar ionic 0.0092 0.010 0.0198 0.0067 CO. 001 0.014 0.0246 CO. 00) 0.00)4 <0.000) 0.0206 0.0024 CO.001 0.005 0. 0.040°

Buryllium

Cadmium 0.0056 0.0214 0.004 0.006 0.0009 0.0054 0.0051 0.00)5 0.0021 0.0018 0.00)8 0.0011 0.0009 0.002U 0.010b 0 10° .. Clirumi uii C0.005 0.0084 0.0099 0.0147 0.0)7) 0.012) 0.0196 0.0185 CO. 005 CO. 005 CO. 005 0.071) 0.0847 CO.005 0.050b

h Cciyur 0.0089 0.024) 0.0084 0.0104 0.0095 0.0105 0.01)2 0.0142 0.0144 0.009 0.0197 0.0)44 0.008 0.026 l.l 0.50e

b l^dd 0.005) 0.00)7 CO. 001 0.0084 0.00)4 0.0055 0.0042 0.0017 0.00)) 0.00)4 0.0051 0.00) 0.005 0.0111 0.0b0 0. lio"

HJ oui y 0.0018 0.0016 0.0016 0.0047 Mi 0.0007 0.0071 0.0028 0.002) 0.00) 0.004 Mi NH 0.0011 0.002b

J Nickel 0.110 O.OUO 0.2)0 0.120 0.016 0.060 0.170 0.090 0.250 0.050 0.190 0.0029 0.002) 0.240 O.OI54 1.0e

^Ionium 0.0091 0.0061 0.0151 CO. 002 CO. 200 0.0079 0.0209 CO. 002 CO. 00 2 CO. 002 0.0267 CO. 200 CO.200 CO.002 0.010b

b Silvur 0.0029 0.0027 0.00)8 0.001) 0.000) 0.0088 0.0049 0.00)7 0.00)9 0.0004 0.0086 0.0018 0.0005 0.0012 0.050 U.10

J •HulliuM

lion 4.0 6.60 51.0 11.2 21.7 5.68 6.90 16. • 11. » 8.0 16.6 4'. 6 40 . 2 10 . 4 0. )y

J HuMai*.-* 0.95 0.52 l.Ud I. ft I.) . 0.48 0.51 1.00 0.70 0.79 0.67 1.59 l.5t> \.'i\ 0.5o'

* - AJul/ioJ by Now Ca^le County Laboratory

C > " - L'uiLiinoi i urobable aourou of dirouiiuiHj INu. diromium ftou >ulyift:thaiiu C . C> H< No Ke^ulta a - Wutir Quality Criteria for Huuun llualtli • flat) and,Drinkinidllty for llumn Hoalth - Adjust.*) for Driiikimj Haler Only (CMM : •* SLiLj iif Delaware Water Quality Criteria for Ui^diar^ea (198)1 f - Mjtir Quality Criteria) Onjdnoleutlc - Fish arid Drinking MaUir (CMA) i] - Sjjoifciary KCL h -• Piu,.ji:J W4CL (EPA, I) Novcinbor 19851 LUalt Values (CMA) TABLE A

An«y Creek l.««ll 111 N«w Castle, Do).Mil c! Groukl Water Quility EfA 5.4.1.nb-t 1984 Swpl

|)l 1 Ilk KhJ Siu 1. ii i- W./l 1 54 W.II 56 Wei t 24 Well 26 WeJ I HI IW-9 IH 1 1 Hell 2'> W..l.-r W.il.'l k^jiadlent ujigradient Ouxnqradjent Downqradlem 1>'<1K)1 JtlltlU Recovei y HeCuvely Hucovery^ Cl Ili-l la Cr 1 1 el l«i

Am iiikjiiy vO.OU5 CO. 005 CO. 005 0.007 CO. 005 cO.0115

b U AlSenl*: vO.OU2 CO. 002 CO. 002 CO. 002 CO. 002 CO. 002 CO. 002 CO. 002 0.050 O.M

1 0.1 yllum 0.020 CO. 005 CO. 005 CO. 005 CO. 005 CO. 005 CO. 005 CO. 005 0. 00000 1 *' 0.005I1'" b C i.lml mi vO.005 0.0066 CO. 005 CO. 005 CO. 005 CO. 005 C0.«05 CO. 005 o.oio H.\"

tltf >jni nil 0.258 CO. 100 CO. 100 CO. 100 CO. 100 CO. 100 cO.100 CO. 100 0.056 0. I5DL'

0|'l> i 0.49U 0.090 CO. 050 0.190 CO. 050 CO. 050 CO. 050 CO. 050 l.ly 0.5e

I I 0.190 0.021 o.oia 0.770 0.019 CO. 002 0.010 CO. 002 0.050b O.I •)()'' • • b M* j .:tn y 0.022 CO.0002 cO.0002 0.0002 CO. 0002 CO. 0002 CO.0002 CO. 002 0.002 0.005''

d Nickel 0.156 CO. 050 CO. 050 0.01) CO. 050 CO. 050 CO. 050 CO. 050 0.0154 !.(.'• b S.Jenl.»l -O.U02 CO. 002 CO. 002 CO. 002 0.00) CO. 002 CO. 002 CO. 002 o.oio 0.02''

b Sll W.-I CO. 005 CO. 00 5 CO. 005 CO. 005 CO. 005 CO. 005 CO. 005 CO. 005 0.05 O.l"

d llullium CO. 010 CO. 010 CO. 010 CO. 010 CO. 010 CO. 010 CO. 010 CO. 010 O.OI78 0.04'

1 Zinc 0.427 0.09) 0.064 0.1(8 0.056 CO. 050 CO. 050 CO. 050 5.0 i.o"

Alkil/

-• Tllea - Prniur/ Drinking WjH r SunLitd ' SujokUry Drinking Water Stanlard -> Miier Quality Criteria for Ihuun llmlLli - Adjiutud for Drinking Mater Only (CMA) ? SMte of tkJ.lwjr - Mdtui Qtulity Criteria For Oiachar > Miier Qmllty Crllerl.i, d'jdiiolept ic - Piali and Drinking Water (CMA) C - Pi,,.i.ol IHiJ. (EPA, I) Nova*U.>r 1985) cr> > A4i>>ir.-iii Tlii.-JKjI.l Limit Val ita (CWA I C/i c TAJJLli 'J

Army Creek Landfill New Castle, Delaware Amy Creek and Pond Water Quality EPA/FIT Sanpling 9-11 November 1981 Organic Concentrations

0) 8 CD 0) 3 62

Station II II UIk. If I (Rt. 13) ND ND ND ND ND ND ND ND

ND ND ND ND II (RR tracks) * *

m (nr. RW-9) ND ND ND ND (discharge)

IV (nr. RW-4) ND (discharge)

V (nr. Amoco) ND 350. ND ND ND ND ND

ND = Not Detected * Indicates chemical present in sanple

o d> C3 CD cn c CO TABLE 6

Amy Laivlli

Ai.iiy o -ek jo. I Pr.kl Mat .-r Quality Inor.jaiiii: Concentration:! (Mj/1 ) Q'./Fir S«f\illnc) 9-11 No/enter 1981

Station II SLrltlOII III SLiI Ion IV Slal lr>n v jot d I CollC. (Bt.lil (MR tracks) (nr; RH-9 dlactiarq (nr. »M ili^H, (nr. ATOJCU) Criteria

AlumiiKini 0. 150 0.400 O.HJO 0.150 0.400 Chr-MiliM CO. 010 CO.010 CO.010 cO.010 CO.010 B.ir iiiM 0.060 0.170 0.270 0.090 0.210 Bor/llluM <0.002 CO.002 CO.002 CO.002 CO.002 O.OD5I1 Calvin* CO.005 CO.005 CO.OOS CO.005 cO.OOS 0.000025 '

Jill I CO.010 I).010 0.020 CO.010 0.050 . CO. 020 CO.020 CO.020 CO. 020 o.no 1.000 I. 760 2.160 25.000 0.860 167.000 CO.040 cO.040 CO.040 cO.040 CO.040 O.I/" CO.020 cfl.020 CO. 020 CO.020 CO. 020 I.84 0. 2'10 0.590 O.BW 0.1)0 0.470 0.050 0.050 0.020 0.020 0.150 0.12" H.. » 0.050 0.080 CO.010 0.0)0 CO.010 V m. i<)i IIID ,0.010 CO.010 CO.010 CO.010 CO.010 21.800 11.600 21.100 20.700 11.600

7.700 1.700 7.500 7.800 5.400 17.900 2fl.)00 16.500 26.700 11.00 Ars.-'iiic CO.010 CO.010 CO.010 CO.010 CO.010 0 04" Anl Imrjiiy CO.020 CO.020 CO.020 CO.020 CO.020 1.61'" CO.010 CO. 010 CO.010 CO.010 CO.010 0.76C

en.010 CO.010 CO.010 CO.010 CO.010 0.041 ' H.-i.Mry CO 001 CO.001 CO.001 CO.001 CO.001 o.oooooI; Tin CO.020 CO.020 CO.020 CO.020 CO.020 Sllw r CO.020 CO.020 CO.020 (0.020 CO.020 0.0041" j •> Crll.-iU for ti:itt^ii Aututlo Life - total r>9-x>v;rablii .Vijuminu a cr> of liW). MJ/I. u CaCo CD c h - Crit?rl.i for Fredliwit-r Ai|>ut ic Life 22 1 ._• - A^Mt! IVmlclly Criteria for Fre;.liwat.-c Asiatic Life ICMAI cr> C • - (\\nr-iiL ItwoJlmld l.lail Value j (CMA) CM C TABLE 7

Army Creek Landfill New Castle, Delaware Army Creek Water Quality

Base/Neutral Organic Compounds (ug/1.)

Bis(2-ethylhexyl) Di-n-butyl Location Date Phthalate Phthalate

Upstream Sept. 1983 13.2 83.6

Downstream Sept. 1983 NF 40. I

Surface Water or 3.0a* 3.0a Cri teria

* Analyzed by New Castle County Laboratory

NF = Not Found

a = Criteria for Freshwater Aquatic Life for Phthalate Esters (CWA) * = Apparent Threshold Limit Values (CWA)

PL- '• o C ' C> . > O en TABLE 8

Army Creek Landfill Ntu Castle, Del a wj re Army Creek Mater Qiulity

Tutal Irorganic Cdiceiitrdtions (raj/1)

Luxition Data • 1 I* I I I I I I I - I I

i, .*un i~4.i . |yb) ,11.010 CO.002 CO.0005 0.0016 0.015 0.0064 0.0127 O.OOOb 0.110 -.O.U'jO cO.OOO'j <0.002 0.0^0 t. /b D.loil

cO.010 cO.002 <0.005 0.0015 0.0176 0.0060 0.0077 0.0001 O.OUO cO.ObO O.OOOb <0.002 0.1)0 J.iyi 11.4111)

bin t n;i: Walc-i , Li" U L" c Ii <• Kb U U d 1 C.lt,.,,., °' < «•««" 0.000025 0.021 0.022° 0.1/° 0.0(10017° I.«° o. 7o O.OOIl'nnd0.004I" 0.04'' ().

CL> C' C) Amlyiol I)/ NvW (JJlle Conn y |jh C/! __ • AH»I( III 'Illli.-ilMllil Lllllil V:•• CWA) " Oil i Jill nil |ly li^i^ii^' flilll dull JIIICI by iLillKj IN) III |ulyn».'l Ibllle iJunl .11 M, I :, .

.1 - W.it, i ^ikilny (,'r 11 ei 1.1 toi Ilimiiu ll'iillli r-iili iiiul Diinkiiuj Wjl ei UWA) b - iMUiu tui r-i, .liw.ilul Aijuil IO Lite (LMA) c - Ciileiia for F(e_>liwt er A"|in( 1C Lift: - Liiljl ri-T.-uvenblt/ dxjii(«)ilkl) ' • - • • '• f I '• -• • .1 .., Ac ii Lit I.- I I I .- Ii Vl« I TABLE 9

Amy Creek Landfill Maw Cattle, Delaware Amy Creek and Pond Sediment Quality TOtal Inorqanle Coneentrations (H>b) Ot«BC Sailing and Analysis

Cuu.viiti il ion St.it i.x Station 2 Station 3 Station 4 Station 5 Station 6 Station 7 Station B

In iii 21,902,000. 9,505.000 44,010.000. 18,530,000. 45,175,000. 27,962,000 2,867 000 18 259 000 167,000. 190,000. 274,000. 398,000. 845,000. 1,320,000. 24,260. 87,020. r|u r»ni inn 18,490. 10,210. 25,540. < 10, 000. 14,920. 14,930. <10,000. 11,570. Silvan clO.OOO. ClO.OOO. <10,000. ClO.OOO. ClO.OOO. clO.OOO. <10,000. < 10, 000. Zinc 87,270. 90.920. 274,000. 70,750. 143,000. 240,000. 22,240 93,060

1^1.1 21,400. 142,000. 175,000. 25,410. 70,630. 56.750. 10,110. 31,690. C.kiiru mn ClO.OOO. < 10, 000. <10,000. < 10,000. ClO.OOO. ClO.OOO. <*,000. ClO.OOO. H.-ioiry <500. <500. <500. <500. <500. 630. <500 C500. Ars.;.nc <3000. <3000. 9260. <3000. 5470. 13,540. C3000. < 3000 . Seloui mn C500. <500. 710. <500. <500. <500. C500. <500.

tidf luni 42,800. 38,310. 234,000. 79,720. 145,000. 76,660. ClO.OOO. 57,380.

Suit ion I - Amy Cr./ok, Wiiil D( Hoiil.; 13 SLition 2 - A nny Cri.-<.-k, Ea it of Roiiti' 13, ttjutiv-din of Weir Slat iim 3 - Ariiy CieckCi , Paul Entr-tno- en Stitimi 4 - Amy Cr,-ok, Pcji.1 Effliwit SI it i. MI 5 - Ajiiy Cr,:.:k, (liil^r Kailro,iii Briiljo Stjl IIMI 6 ^ Aniy Cr,;.,-k, Tiilil <'*tl

* TVjxicity IIMm i j, tlil.; ul ration u> l,»ml-oL-oli>jic' CWGI.NAi Precipitation f'Red: Diagrammatic water budget

G4K>t«rtfl4) \Drain Percolation through soil

Percolation through cap(Si%)

Percolation through waste material Exiartlng grade Percolation through existing soils

d - Slope angle

MULTILAYER CAP SYSTEM PROFILE

FIGURE 5 A R U u U J 1 0 vegetated Layer Horizontal Drain Layer Multilayer Low Permeability Soil Cap Drainage Barrier Layer System Ditch Regraded Surface To Treatment/ Discharge I*

Upgradient Existing Soil Fill Interceptor Cover Surface (Local Granular Soils) Well Existing Refuse c > o C/!

a m

N-S CROSS SECTION: ALTERNATIVE 4 A Well Point System Final Cover/Cap System to Dewater the Saturated Refuse Before Reburial Will Be Required- Discharge to Treatment Reburial of Removed Refuse \ \ Refuse to be Removed; Area to be Backfilled with Clean Soil Fill

C > c c_•> C/i (J

o c m ^ W-E CROSS SECTION: ALTERNATIVE 5 C ' c> TABLE 10 d.) en REMEDIAL METHOD COST ESTIMATES - Army Creek Landfill o Remedial Method Total Capital Total Monitoring/Maintenance Cost Total Present WoiIh Cost Annual Present Worth <• ' ' Cost. i. No action - monitoring $250,000 $113,000 $1,065,000 $1,315,000

Downgradient pumping $120,000 $272,000 $2,565,000 $2,685,000

Uowngradient pumping and landfill capping $12,030,000 $307,000 $2,895,000 $14,925,000

Uowngradient pumping Non-phased $12,340,000 $393,000 $3,705,000 $16,045,000 landfill capping and Phased $12,030,000/ upgradient pumping $310,000(2) $306,000/$87,000<3> $3,140,000 $15,290,000

Partial removal and on-site disposal, $35,500,000 $296,000<4> $2,430,000 $37,930,000 capping and downgradient pumpi ng

On-siLe incineration $113,500,000 $272,000 $2,565,000 $ 108,250,000 O and downgradient pumping

Oft-site disposal at an approved landfill and downgradient pumping $239,900,000 $272,000 2,565,000 $243,000,000

(1^ Assumes present worth valifes based on a discount rate of 10X over 30 years.

(2) Assumes construction of upgradient pumping in 10 years @$310,000.

(3) Assumes operation of upgradient pumping in 10 years @$87,000/yr. .75

(4) Anticipated annual cost for 15 years after which annual cost is redyped to $96,000.

(l>) Tliis cost estimate is a result of subtracting the revenue figures from the total cost ol the project. TABLE 11

ilM-WHY bVAJJMTKW O RtMQJlAl. MLTUM A1.1W

UI.T ($1,000) TBJWICAi. QUNLtWNS PKCJBfT HIUI.IC IKALTII AND < PBIU-XWMAJO:-ra. i AB 11. m tKHTS OOMNIfY EWIRUWDfTAL (XMCEHHS IMHAMOffMlLlTY-SAfETY I RESPONSE CCNCEfMS

1. No-Act ioii 1,115 Without hydroltqlc cuittola, Publicly Unacceptable not attain o Monitoring Only the contaminate plum* will Does not follow pcui>osuJ aii'llcable public •igrate further dOMirjradient, guidelines of the ETA liealth ami environ- ruaultlnq In potential htinan Ground water Protection m-'iital standards. eicpaMue by 1090911 on uf or- Strategy- (CtXLCA) ffuilc oonatltuenta above the 10 Health Risk Criteria. Itw continued proJuction of leactate, ujuld not be con- trol led continuing lopact on Col until a and Potcwuc ai|ulf er.

2. 2,685 Keducea public health risk Daunjradlent recovery Tile discharge of recuv rut attain o Monitoring by containing the contawl- •yste* has to date a ered/treated ground water ajipl I cable environ- o Discharge U> A|VIO~ nant plune by mana of a history of effectiveness, •UBt be perform*! within mental standards - i* late hydrologic divide. fatter quality of down- necessary permitting/ present cover over graJlent water production approval process. tVUES landfi 11 does not Itas prevented poeslble abaii- supply wells has been permit required If treat- met RCRA guidelines. doment of Pot owe aquifer aa BBintalned. ed discharge is to Army source of water supply. The Creek. quantity of leachate generated Syate* requires periodic fro» precipitation and ground rehabilitation and water Infiltration through •alntanance. the landfill will not be re- duced - inpact en environment will continue.

IX>fl*jradieiit Punping 14,925 Public health risk reduced by Itogradlng and backfilling Ttie discharge of recov- Tliis alternative at- o Monitoring oontatnlrvj the contaminant of the existing cover la ered/treated ground water taina a(j|>licable and o Diat^iarjt) to pi we by auans of a hydrologic required to establish a •uat be perfonud wltliln •)e*'*it public health |iriate divide. aite contour pattern to necessary permitting/ and en..ronmeritdl prunote run-off auay fro* approval process. NPues standards. C > Idmif i II Ca|iplng Infiltration of precipitation landfill. Hagradlng to permit required if treat- o Site Hegradlng and through the landfill will be flatten out existing ed discharge ia to Army c > Surface Hate Diver- reduced over 961 by capping slojiea to assure slope Creek. cr> Die landfill, tkihiclng lea- stability my be raquirad. C/! diate production should hasten TABLE 11

(cm it inuul)

UKI' ($1,0001 TULIWICAI. QMCKKNS Hllll.1C lt*l.ni AM) COMMMY Al.Tt-HNATlVE MUKTII ENVI MOMENTA!. UNJUMS RESPONSE QNCKRNS j. (ountinuul)

o Gaa Vailing ground water cleansing but at Side slop>;s In tlie flood Iliere are HL'HA ilesiijn an unknown rate. Infiltration plain must be protect**! standards for bur face Into landfill of ground water with rip rap oovcr. capping. Projxwul cap from Columbia aquifer along will meet RCRA guidelines. northwestern side will oun- tlnue. Contamination of both Public concerns about now Columbia and Pot owe aquifer activity at tile landfill continue. site must be addressed. Ail state erosion, sedi- ment, and dust control ordinances would apply during construction and until a vegetated cover Is established.

15,290 Public iKdllJi risk reduced by Sane as I) L In addition) Seine as I) fc In aildition, llnli-r the (rfiasul ,i|, cuutalning the oontamlnant The efficiency of the up- well Installation permits irodch the effect >n Hua.-' I plume by means of a hydrologic gradient pumping well for the new n>jr<*llen( the groujHl wuti^r DlMIKjrddient PuB|>ilKJ divide create by downgradient scheme Is largely depen- wells have to be obtained qual Ity aa a result o Monitoring pumping. dent on the amount of re- fro* the State of of capping the Idifcl o Discharge to Ap- charge through the land- Delaware. fl 11 wi 11 be uunitoiul proriate Treat- Infiltration of precipitation fill and the voter level and assessed |« ior to ment through landfill reduced over elevations In Army Creek. Initiating ujigiadient 961 by rapping the landfill. punping. landfill Capping Present cover or ov Idea only As with the downgradient o Site Rugrading I 12% reduction In infiltration. system, the upgradient will Tins alternat ive Surface Miter require periodic rehabil- attains a(i()licable and Diversions Upgradient pumping network itation (initially) and relevant public h>-,ilih o Gas Vaiting will algnif leant ly reduce the maintenance. aiki envi i onniental C > ground water entering landfill staiulards. Huse 2 . along northwestern side, re- c Dpgradlunt Controls dicing further leachate produc- C-> o Mill luring tion. en o Discharge U>, Ap- pro(>rlate Tre.«t - Alter initiating meiit limiting (Plia^e 2) short-term c: effect Id uuntlnuul use of a witer resource, llpjijd ient |jun|)ins (jjiifilng uf n. I work .

(or TABLE 11

(ountinuud)

OUbf ($1,000) TEUMICAL OMCKHNS INSTIIUrKWI. REQUIRE- PRESENT KJBLIC IKAI.TH AND (PERTOIMANCE-REI.IABII.rrY ' MENTS ooMMrrY ALTERNATIVE _ _ MtJfrTH EMVIRCj«4EMTAL CONCERNS IMPLfMEHTABILITY-SAFOT I RESPONSE CONCERNS COttfOTS

4. ami inuul Nun-Rust*! Aifxoach 16,045 Sanu aa |4a Saw as |4a 14 Llmler the non-p!iadud ajiprodcti all raitadial action will be Initi- ated simultaneously.

5. partial Huoival and 17,910 Public Health Risk reduced by Refuse In western part Same as |) In addition, This alternat ive Disposal Oi-Site containing contaminant plums. below the water table odor would be a signi- attains applicable o RajraJIrvj, Back will have bo be dewatered ficant concern to the and relevant puhllc fi Illng, Surface Addresses environmental b»- by ujjgradlent pimping. local public. Increased health and environ- Mater Diversions (jocl caused by ground water Recovered water will noise is also a concern mental stanrvirds. infiltration by eliminating require treatment. during excavation and l*tti*if i 11 (Jailing the source of leachate gen- disposal operations. o Gas Vuitlng eration and has additional Free liquid drainage and benefit of not rexoving ad- dust can be oontrolled Ikwii ji jdieiit Puii|>iivj ditional water from local using standard construc- o Mmitoring source aa in Alternative 4. tion approaches but odor o Discharge Lo A||>ro- will ba more difficult. [* late Trealmenl Capping of eastern section after removal and disposal of A potential slops stability western section will signifi- problem may result along cantly reduced precipitation the exposed cut section be- infiltration. Source removal tween the eastern and west- and capping of landfill will ern section aa excavation hasten a ground water cleans- results In deep aits into ing reducing long-term pimping. refuse. C c:> During excavation dust t odor Special/hazardous wastes en- problems will occur aa well countered will require CTi as the draining of free water special handling and tran- fro» saturated refuse. sport.

On Site Inclnerallixi 108,000 Sane public health and envir- Suitability of Potomac lance with Delaware This alternative was o Ccmpl>?le Removal onmental benefits as Alter- tarjutlon bo aupport in- Solid Waste Autliorlty'a screened out because o Diwaterlng of Refuse natives 4 and S. Air pollu- cinerator foundations. •aster plans. Its cost Is of an by Uri jr ad lent Pumping tion control devices required order of magnitude under RCRA will reduce the re- Raw refuse from off-site On-Site Incineration re greater tlian Alter - (Xwngradient Pumping lease of contaminants Into will be transported to the gulated under RCRA. A natives 4 and 5 which o MonI tor Ing the air. alte and mixed with the Hazardous Haste Manage- offer similar public o Discharge to Appro- saturated waste to mike ment Facility Permit ia health and environ- priate Incinerator ash and residue It burnable. required. mental benefits. backfilled on-site In areas above ground water table. oj)(«wltl<»i mil tie anticipated. TABLE 11

(continued)

($1,000) HJB1.IC ItAI.III AND (PEWOKMANCE-HKUABII.rrY ft-wrs AjL-rKKNATIVE vumt EWlBONHEMTAl. CtMCERNS IKPUHEMTABItm-SAFETK > HESFCMSE UMC£HNS

6. cunt imual Uuut, odor, and drainage of free liquids fro* the saturated National Ambient Air was,te are problems associated Standards (NAAQS) ap|>ly - with the excavation of landfill will require Clean Air Act •refuse. (CAA> permits. Other environmental and health concerns are with transport of raw refuse to UK) Army Creek Site including noise, dust and (received vector problems.

7. Oft Site l>Ui«*,.il l;y 241,000 Sane public health and envir- Availability of RCRA TidiisixH tat Ion of luzanl- aa |6. Ixiiulf i II nxj on A|(Jiovud onmental benefits aa Alter- approved sites. cus waste to an off-site Site natives 4, S, and 6. Dust, disposal facility re>)ulres o Oinpl^'e Ktiiiovdl of odor, drainage of free water RL'RA TSDF permits. landfill fro* the saturated refuse, o OtWtitur ing ol Sat- and noise problems will arise public ujipositlon to tliia urated Refuse by fro* the excavation and haul- alternative resulted In (Ipgradient Pumping Ing operations. the cancellation of an earlier plan for a dis- pun|>ing posal site adjacent to o Monitoring Army Creek site. o Discharge to Afjiro priate Treatment

C C ' C ' t/: ro c: RESPONSIVENESS SUMMARY

ARMY CREEK LANDFILL SITS NEW CASTLE COUNTY, DELAWARE

SEPTEMBER 1986

This cotitijnity relations responsiveness simmary is divided into the following sections:

Section I: Overview - A discussion of the EPA's preferred remedial action alternative. Section II: Background of Community Involvement and Concerns - A brief history of the community's interest in and in- volvement with the Army Creek Landfill Site, including a discussion of concerns raised by community members and officials during remedial planning activities. Section III: Summary of Public Comments Received During the Public Comment Period and Agency Responses - A summary of comments categorized by topic and followed by EPA responses. Section IV: Remaining Concerns - A description of remaining commonity concerns that should be considered as the EPA and the State of Delaware Department of Natural Resources and Environmental Control (DNREC) conduct the remedial design and remedial action at the Army Creek site.

In addition to sections I through IV, a list of EPA community relations activities conducted at the Army Creek site is included as Attachment A of this responsiveness summary.

A R U u U 5 c I - 2 -

I. Overview The Remedial Investigation (RI) Report and the Feasibility Study (F3) Report v«re released to the public for review and comment on August 21, 1986. This narked the opening of the comment period, which extended until September 22, 1986. During the ccmment period, the EPA recannended a preferred remedial alternative frcro among the seven alternatives presented in the FS report. After careful review of and consideration of all alternatives developed in the FS, the EPA and DNREC recommended the phased approach described in Alternative 4. This alternative includes the following components: 0 Regrade the landfill surface to assure a finished compacted surface and install a capping system to minimize infiltration of rainwater. 0 Continue the operation of the downgradient recovery well netvork. 9 Evaluate the capping system and the downgradient pumping network for five years after the cap is installed to assess systam effectiveness during operation. This evaluation would include, but not be limited to, monitoring water levels, pumping rates and water quality. 9 After the evaluation period, if conditions necessitate, install upgradient controls to intercept lateral groundwater inflow on the northwestern boundary of the landfill. 9 Continue monitoring of water levels, pumping rates and water quality.

II. Background of Community Involvement and Concerns The Army Creek Landfill Site is located 2 miles southwest of New Castle, Delaware. The site is located on the northwest bank of Array Creek, which discharges into the Delaware River within 1 mile of the site. A residential development of more than 200 homes, Llangollen Estates is the nearest and most directly affected community. Just beyond this residential area lies the Artesian Water Company's well field, which supplies water to approximately 5,000 people. The site was originally used as a sand and gravel pit. The New Castle County purchased the property in 1960 for use as a municipal landfill. Waste was deposited fro* 6 to 35 feet deep over an area covering 44 acres.

A Pi u u U t) c. - 3 -

The residents of Llangollen Estates expressed their concern over the landfill as early as 1960, when plans for the municipal landfill were announced. The Llangollen Estates Civic Association filed an un- successful legal action to prevent the Landfill from opening. Throughout the active life of the landfill, residents of Llangollen Estates complained of rodent and odor problems. The number of complaints decreased substantially after the landfill was closed and covered with sand and soil. In 1971, one Llangollen Estates resident complained that the water in her home had an odor and stained her porcelain fixtures. The water was analyzed and found to be contaminated, as was water from several other private wells. Present-ly, most Llangollen Estates residents are receiving municipal water supplied by the Artesian Water Company. Residents of Llangollen Estates have followed closely the activities of all government agencies involved with the Array Creek Landfill. However, communication between government agencies and citizens during the time between signing of the FS Consent Order with New Castle County and release of the FS document was limited. This lack of communication was a major concern voiced by citizens during the comment period.

III. Summary of Public Comments Received During the Public Comment Period and Agency Responses Technical Questions/Concerns Regarding Remedial Alternatives 1. A resident asked for an explanation of upgradient controls. EPA Response - The installation of upgradient controls is an option to be considered after the five-year evaluation period. The capping system and the downgradient pumping network will be evaluated for five years after the cap is installed to assess the system's effectiveness. If necessary, upgradient controls such as recovery walls upgradient of the landfill or trenching around the landfill would be installed to prevent lateral flow through the fill material. 2. One ccanentor asked what was being done at present to control the contamination into Army Creek. EPA Response - Contaminated groundwater pumped from the recovery wall system at the Any Creek Landfill is discharged into Army Creak. Presently, DNREC is drafting an NPDES permit which will establish safe and appropriate levels for contaminants now being discharged into Army Creek. 3. One conmmtor questioned if the quality of the recovery wall water would improve upon completion of the remedial action and if so, would it be plausible to pump this water into the Wilmington Waste Water Treatment Plant instead of into Army Creek. - 4 -

EPA Response - Once the landfill is capped, the quality of ground water should improve. Pumping into the Wilmington Waste Water Treatment Plant is an option that will be addressed at a later date. 4. A resident asked how much water was presently being pumped into Army Creek. EPA Response - Approximately two million gallons per day. 5. Another resident asked how close the contaminants are to the well field. EPA Response - The contaminant plume extends to approximately 1500 feet away from the Artesian wall field. 6. Several comraentors questioned the timetable for the remedial action. EPA Response - Negotiations with responsible parties generally are limited to 90 days. It is anticipated that the Record of Decision (ROD) will be finalized by September 30, 1986. The actual design phase of the project could take up to one year to complete. After the design phase, the remedial action will be implemented. Once the action is completed and the cap is in place, the site will be monitored for five years to determine if the levels of contamination decrease. An evaluation will then be made regarding the need for upgradient controls. 7. One resident questioned what factors the Feasibility Study (FS) took into consideration. EPA Response - The Feasibility Study considers not only what contaminants are in the landfill, but the pathways by which exposure can occur to both hunans and the environment. The purpose of the FS is to evaluate various alternatives to remediate the source and the contaminated groundwater. Public Haalth/Environasntal Concerns 1. A resident asked if anyone could say with reasonable assurance that there will not be a lateral flow of contamination into the landfill. EPA Response - .EPA will evaluate the effects of any lateral flow upon completion of the cap* If the effects are significant, upgradient controls will be installed. Public Participation Process 1. Several residents expressed their concern over the lack of information and opportunities for public participation at the Army Creek site.

A ft u U 0 5 c - 5 -

EPA Response - EPA representatives offered to make themselves available for small group meetings to discuss the FS in detail. EPA also stated that there will be many more opportunities in the future for residents to be involved with the decisions made at the site. 2. Several ccmmentors requested additional time to review the FS and the preferred alternative. Several residents said they were outraged at being given only 21 days to comment on a study that took 2 years to prepare. EPA Response - A decision to extend the public comment period could not be made at the meeting, but would be taken into consid- eration with the other comments received, both written and oral. (The comment period subsequently was extended from September IS to September 22 as a result of this request.) EPA explained that citizens would have input for the duration of the project, and that this Record of Decision could not address recovery wall discharge. 3. Some residents indicated that EPA should begin the cleanup as soon as possible, and that additional delays should be avoided. EPA Response - None. 4. A representative of the Llangollen Civic Association asked if EPA would meet with knowledgeable community members once they had a chance to review the FS. EPA Response - Agreed. Cost/Funding Issues 1. A commsntor questioned what the cost of the remedial action would be. EPA Response - The present worth cost of the remedial alternative over the next 30 years approximately is $15 million, this includes capital costs. 2. One resident asked how much New Castle County had spent to date on ths> Ana/ Creek Landfill. EE* Response - New Castle County has spent $3.85 million to date on the feasibility Study and the installation, operation, and maintenance of the recovery walls. 3. The Artesian Water Company claim that its pumping capacity has been reduced due to groundwater contamination. The company believes it should be compensated for this loss as part of this CERCLA action. - 6 -

EPA Response - This question has been discussed at length by EPA, the Artesian Water Company ("Artesian") and New Castle County before and during generation of the Feasibility Study. It is Artesian's position that it has been forced to draw less water from its wellfield because of the contamination leaching from Army Creek and operation of the recovery well system. Artesian regards the reduction in capacity as a response cost under CERCLA. New Castle County is of the view that, if Artesian has lost any capacity from the wellfield, it is for reasons other than pollution from the landfill. The County has argued that Artesian has never been entitled to draw more water than it presently takes from the wellfield, by virtue of state authorization and salt water intrusion. Artesian has sued New Castle County, and some other parties over this question, and no final resolution of thaf case has been reached. Both Artesian and the County vigorously presented their respective positions to EPA during preparation of the Feasibility Study. The regional staff consulted with headquarters about this issue, and the final result was a memorandum from Gene A. Lucero, Director, Office of Waste Programs Enforcement, to Steve Wassersug, Director, Hazardous Waste Management Division, Region III. In short, the position of EPA is that replacement of aquifer capacity is not a goal for this CERCLA cleanup. The wellfield currently in use is being protected by the existing recovery wall system, and other remedial measures recommended for this site should prevent future contamination of the aquifer related to contamination from the landfill.

H n! u u u D

Community Relations Activities Conducted at the Army Creek Landfill Superfund Site.

o August 3, 1984 - EPA announced signing of a Consent Order with New Castle County to perform a Feasibility Study for the Army Creek Landfill. 9 November, 1984 - EPA completed a community relations plan. 0 August 18-20, 1986 - EPA contacted local officials and citizens regarding release of the FS and set up information centers in the community. 4 August 21, 1986 - The FS was sent to 4 information centers, and a press release announcing completion of the FS was distributed. • September 10, 1986 - A public meeting was held to discuss the findings and recommendations of the FS. • September 15, 1986 - The comment period was extended until September 22, 1986.

H•~ Di\ U~ .u" :U~ CJ '(_ ^ Consent Decree Exhibit 1

Army Creek Record of Decision OU-1

Army Creek Landfill Superfund Site New Castle County Delaware RECORD OF DECISION

REMEDIAL ALTERNATIVE SELECTION

Site: Amy Creek Landfill Site, New Castle County, Delaware

Data Reviewed The underlying technical information, unless otherwls«d specified, used for analysis of the coat-effectiveness and feasibility of remedial alternatives is Included in the following documents and project correspondence. I have been briefed by my staff of their contents, and they form the principal basis for my decision of the appropriate extent ot remedial action. Feasibility Study for the Army Creek Landfill, New Castle County, Delaware, (Roy F. Weston, Inc., July 1986) Endangerment Assessment, Army Creek Landfill (Richard L. Zamblto, U.S. E.P.A. Region III, July 1984) rlydrogeochcmlcal Studies at a Landfill in Delaware (Mary Jo Baedecker and Michael A. Apgar, 1984. Studies in Geophysics. Groundwater Contamination, National Academy Press) Recommendations by the Delaware Department of Natural Resources and Environmental Control Staff summaries and recommendation* Description of Selected Remedy * An initial operable unit for source control* to be implemented In « two-phased approach. Phase L * Install a RCRA type cap to minimize infiltration of rainwater. Capping of the landfill will Include site clearing, regradlng of the existing cover surface, adding soil backfill to achieve grade*, installing the cap with gas vents, and construction of drainage ditches to direct run-off *w*y from the landfill. * Continue operation of the downgradient recovery well network. * Evaluate the capping system aad the downgradient pumping network for five years after the cap 1* installed to ***e** effectiveness of the system during operation. Thi* evaluation will include, but not be Halted to, monitoring water level*, pumping race* aad water quality. -2-

Phase 2 * After the five year evaluation period, a determination will be made on whether to install upgradient controls to intercept lateral groundwater inflow on the northwestern boundary of the landfill. 9 Continue monitoring the water levels, pumping rates and water quality as in Phase L. 0 Operation and maintenance (0 & M) will include as a minimum, regular Inspections and, as necessary, repairs to the RCRA cap. The groundwater recovery system will be monitored to assure that it 1* capturing the contaminated plume. Selection of a treatment alternative for the groundvater recovery well discharges hau not been made at this time and will be the subject of a second operable unit decision document in the future. A groundwater treatment remedy ha* not been selected, because the final NPDES permit ha* not been issued. In addition, the Remedial Investigation/Feasibility Study (RI/FS) at the Delaware Send & Gravel Superfund site adjacent to Army Creek Landfill, has not been completed. It i* our intention to combine the remedial action* for these two sites wherever coet-efreceive. Also being deferred at thi* time i* a decision on appropriate remedial measures for sediments in Army Pond. Thi* decision will be made «t the same time a* groundwater treatment 1* considered and after further analy*!* 1* accomplished regarding the actual impact* on Army Pond. Declaration* Consistent with cha Comprehensive Environmental Response and Compensation and Liability Ace of 1980 (CERCLA) (42 U.S.C. f 9601-9657) and Che National Contingency Plan (40 CFR Pare 300), I have determined chac che remedial aceIon described above, together with proper operation and maintenance conaclcuce* a cost-effective remedy which mitigate* and minimize* damage co public health, welfare, and the environment. The remedial action provides for capping Che site, continuing operation of existing downgradient groundwater recovery walls, and Che installation of upgradient groundwater control* in cha future aa necessary and, therefore, minimize* the threat of further concaalnaelon of the environment. The remedial action does noc affect or violate any areas. A portion of the remedy may encroach slightly ineo the floodplain ae che vouch end of cha alee. If during detailed deaiga, aurray work **eabli*he* thi*, special maaauraa will be taken to minimize cha encroachmenc and eo proeece cha remedy, the Scaee of Delaware ha* been consulted and agree* wich the approved remedy. In addicioa, cha action will require future operation and malneenaace activitiea co enaur* che continued effeceivenea* of the remedies. These ace1viela* will be considered pare of the approved action aad eligible for Trust Fund aoalaa for a period of six month* following coapletioa for construction. -3-

I have determined that the action being taken ia appropriate when balanced against che availability of Trust Fund monies for use at other sites.

EIF MINISTRATOR

A R U U U J 3 i SUMMARY OF REMEDIAL ALTERNATIVE SELECTION

A. SITE LOCATION AND DESCRIPTION The Army Creek Landfill formerly known as the Llangollen Landfill, is located approximately two miles southwest of the city of New Castle, Delaware (Figure I). The landfill is bordered to the north and west by tracks of the Penn Central Railroad and on the south and east by Army Creek. The highways adjacent to the Landfill are Routes 13 and 40 to the west and Route 9 to the east. Llangollen Estates, a residential development is located 1/4 mile southwest of the site. The former Amoco Chemical Plant, closed in 1980 due to fire, is located 1/4 mile eaat of the site. Delaware Sand and Gravel, another landfill which has been placed on the Superfund National Priorities List, is adjacent to Army Creek Landfill and separated from it only by Army Creek, a tributary of the Delaware River. The Army Creek Landfill, a former sand and gravel quarry is owned by New Castle County. The County operated this 44 acre landfill which accepted municipal wastes from 1960 until its closure in 1968. During that time, an estimated 1.9 million cubic yard* of refuse were landfilled ac che sice, 30 percent of which (or approximately 600,000 cubic yards) now lies below the seasonal high water table. In late 1971, water in a residencial well southwest of the landfill developed quality problem*, such a* a distinctly disagreeable odor and permanent staining of porcelain fixtures. New Castle County and its consulcant, Roy F. Weston, Inc., of Wesc Chester, Pennsylvania, began a multi-year field investigation to assess the problem. Results from that investigation showed that leachate most likely originating from the Army Creek and Delaware Sand and Gravel Landfills, was contaminating local aquifers. Weston's remedial investigation lead to the Installation of a groundwater recovery system designed Co maintain a ground water divide between the landfills and the Artesian Water Company Wellfield located downgradient of the landfills. Contaminated groundwater pumped from the recovery well system was discharged to Army Creek. In August 1984, EPA entered into a Consent Order with New Castle County to perform a Feaaibillcy Study (FS) at the sice. B. SITE GEOLOGY The Army Creek Landfill ia located within ehe Aelaneic Coastal Plain physiographic province. The coastal plain is composed of a wedge-shaped body consisting of gravels, sands, silts and clays. The sice is underlain by two wacar-baariog formacions, ehe Columbia and che Potomac. The Columbia, Cha upper-mo*C aquifer beneath cite landfill, 1* T>f -2-

Pleiscocene Age and is from 10 to 60 feet chick at the site. This formation, which dips to the southeast, consists of medium to coarse grained sands, gravels, silts and clays which were deposited in shallow lens-shaped channels (Figure 2). The silt and clay units of che Columbia are discontinuous and do not form confining units. The Pocomac Formation of Cretaceous Age underlies the Columbia Formation and is generally separated from it by a confining clay layer at the site. The Potomac Formation dips to the southeast, is up to 600 feet thick and consists of silts and clays interbedded with sands and some gravel. The formation is divided into upper and lower units which are separated by a thick confining clay unit. The upper Potomac Formation silts and clays are discontinuous and non-uniform; in some places, the sands of the Columbia and Potomac are in contact. C. Site Hydrogeology Hydrologically, the Potomac upper clay function* as a confining zone for the underlying aquifer which is known as the upper Potomac Hydrologic zone. The direction of flow in the Potomac aquifer has been altered significantly over the past several decades due to withdrawal of water for industrial and domestic uses. The elevation of the potentiometric surface in the 1950's, before significant development of the aquifer, was about 6 meters below sea level and flow direction was toward Delaware Bay to che southeast. In the 1960's, after wellfields were developed in the Potomac Formation for public water supplies and Industrial use, the direction of flow remained to the south and east. Artesian Water Company, a private water company servicing 5,000 customers in this area, completed Its first well at Che nearby Llangollen Wellfield in 1952. By 1961, shortly after the Army Creek Landfill opened, there were four operating wells withdrawing water from the Llangollen Wellfield at an annual average rate of about 1.42 mgd (million gallons per day). In early 1966, Artesian completed a new well and had Increased it* average pumpage to approximately 1.62 mgd. In 1969, a sixth well was added and the annual average pumpage from the Llangollen Wellfield increased to about 1.74(mgd). In late 1971 and early 1972, five more wells were added to Llangollen Wellfield. By late 1971, Artesian had increased its pumpage to an annual average of 2.60 mgd. Since then, Artesian Water Company ha* had Co decrease pumpage to 2 mgd in order to slow down ehe migration of the contaminants and to avoid contributing to the problem* of salt water intrusion that had become common in the area. There has been considerable litigation between Artesian Water Company and New Castle County, over groundwater use. The precise amount of water which Artesian had withdrawn In Che oast, or is presently entitled to withdraw is unclear. Amoco Chemical Company initiated groundwater withdrawal from the Potomac aquifer in 1961 for use in their plane operation*. Pumpage by Amoco we* discontinued in 1980 when Che plane cloaed due Co fire. 1C ha* been estimated that pumpage from che upper Potomac aquifer had

A K u u u ^ 3 J -3- increased aore than seven fold from 1952 to 1972 as a result of groundwater withdrawals from Artesian's Llangollen Wellfield and the Amoco Chemical Company plant wells. During this period, it has b«en reported that the Increased pumpage caused the static water level in Artesian's Llangollen wells to decline up to 65 feet. This decrease in water level resulted in a steepening of the hydrologic gradient in the upper Potomac aquifer which accelerated the migration of pollutants from Army Creek and Delaware Sand and Gravel Landfills toward the Artesian and Amoco production wells. In late 1971, when one of the residential wells in the vicinity of the Army Creek Landfill, became contaminated with Iron and other chemicals, New Castle County determined that the leachate generated by the landfill was contaminating the groundwater in the area. The leachate is produced by water entering the landfill in two ways: 1. Through direct precipitation on, and infiltration through, the landfill surface. 2. As groundwater moves laterally into Che saturated lower portion of the landfill. Analysis of water inflow to che landfill is accomplished by dividing the landfill into two sections (Figure 3). Section 1, che western section (estimated area - 760,000 square feet), receives boCh surface water and groundwater inflow, and generally has a continuous clay floor of relaCively low permeability. As a resole, there exists a relatively thick zone of saturation in this portion of the landfill. Section 2, the older, eastern section of Cha landfill (estimated area - 1,350,000 square feet), receives water primarily by infiltration of direct precipitation. In Che vicinity of Section 2, Che contact between the Columbia and the upper aquifer of the Potomac Formation is often a quite permeable zone. Here the Potomac clay deposits are relaCively chin, sandy, or are absent. Consequently, water in che Columbia sands moves downward Co che Potomac aquifer rather than laterally through che landfill. In addition, the Columbia sands have been excavated northeast and south of Che landfill. Therefore, elevations at these points and in Che marsh to the east are lower Chan chose of the landfill surface and, in places, lower Chan much of the Army Creek Landfill floor. The surface of che landfill is pocketed with depressions, resulting from the differencial subsidence of Che refuse. These depressions, coupled with the remaining flat surface of ehe landfill prevene stormwater from running off the landfill. The cover ia generally silty, sandy and quite permeable. However, deposits of clay have accreted in che depressions so that stormwaeer forma ponds in the depressions. These ponds concribuce co che slow infiltration of water into che landfill. Because of cheae. surface condleiona, ie 1* estimated that ac leaae 50 percent of che precipitation which falls directly onCo eha landfill surface inf11trace* through cha landfill cover and percolate* through the refuse.

A a U U U o J -4-

D. SITE HISTORY

The Army Creek Landfill occupies an area that was formerly utilized as a sand and gravel pit. The gravel pit in which Army Creek Landfill was constructed, was excavated until a hard zone was encountered. This zone marks the base of the Columbia Formation and the top of the underlying clay.

In 1960, the landfill began operation as a municipal refuse landfill. The landfill was operated by New Castle County continuously until 1968 when it was filled to capacity. Refuse placement, compaction and covering operations at che Army Creek Landfill were carried out by the operators of the gravel pit under contract Co New Castle County. Refuse burial began at the eastern end of che pit and generally continued coward the pit entrance on the west. The refuse was generally not well compacted and not regularly covered. The cover material used was obtained from the pit and includes residential sands, tailing piles and siltation basin deposits. As the operation progressed, cover material and landfill space became depleted. This encouraged deeper excavation which may have removed much of the clay layer which separated che Columbia from the Potomac formations. This in turn, could have created direct access routes for leachate to the Potomac from the Columbia. Direct access routes may also have occurred naturally due to the non-continuous geometry of che Potomac clay. Improper covering, along with non-consistent compaction and decomposition of the waste materials, may have contributed to the differential settling of the waste material which has occurred since the landfill was closed. In 1970, the landfill was covered with sandy material and the property was purchased by the County for use as a park. In late 1971, water in a residential well downgradient of the Army Creek Landfill Site developed severe quality problems. Evidence of these problems was the odor of the water and staining of the porcelain fixtures in Che residence. In June 1972, New Castle County commenced a groundweter monitoring program which began with a well installation and sampling program. Monitoring by various agencies including EPA, United States Geological Survey, (USGS) New Castle County and the Delaware Department of Natural Resources and Environmental Control (DNREC) as well as the University of Illinois has continued up to che present. Monitoring has resulted in the identification of groundweCer contaminants indicative of hazardous waste disposal as well as typical municipal refuse. It waa also determined that the plume of these contaminants we* moving Coward* the receptors located downgradlent of che landfill. After considering alternative water supplies for the affected residents, New Castle County paid for an extension of Artesian's Water supply lines to the first coneamlnated residence and other homes along Grantham Lane. There was also a sectlement with the homeowners to offset the monthly services costs. In 1973, recovery well* RW-1, RW-2, RW-3, RW-4, RW-5, RW-6,27,28,29, 31 and 53 were Installed in che upper Potomac Aquifer by Roy F. Weston under the direction of New Caacle Couney (Figure 4). The purpose of che recovery wells was Co intercept and contain che contaminant plume. The pumping of these wells created a groundwater divide beCween che Army Creek Landfill and che Artesian Water Company's Llangollen Wellfield. Beginning in 1977, the

u u U o 3 J -5-

recovery wells showed a pattern of stability in water quality.

In November 1977, New Castle County conducted a technical Round Table Conference in order co obtain input and opinions from nationally and Internationally recognized authorities regarding the remediation of the contaminated groundwater in the vicinity of the landfill. As a result of the Technical Round Table Conference, a modified recovery system was installed in 1980, which included placement of new recovery wells closer to the landfill in order to pump more concentrated groundwater and therefore less clean water. The present recovery well system utilizes Wells 27, 28, 29, 31, RW-1, RW-9, RW-10, RW-11, RW-12, RW-13, and RW-14. US EPA has been involved at the site since 1974, when EPA representatives sampled the recovery wells for the first time. Since then, EPA has sampled che wells in 1977, 1978 and 1981 for priority pollutants. Baaed on che sampling analysis from the recovery and monitoring wells, the Army Creek Landfill site was proposed for the National Priorities List (NPL) in October of 1981 and was finalized on Che Use in September of 1983 due to extensive groundwater contamination. In August 1984, EPA sneered into a Consent Agreement and Order with New Castle County Co perform a Feasibility Study at che site. New Castle County submitted the final draft of the study in July 1986. E. CURRENT SITE STATUS Groundwater Since early 1972, intensive field studies have been conducted by che County, through its consultant Roy F. Weston, Inc., to evaluate che nature and the extent of the problem and to define and Implement necessary controls to mitigate the groundwater contamination. These efforts included the installation and operation of the recovery wells in 1973, and monitoring and sampling of the recovery and monitoring wells. The analytical results from che various sampling efforCs have demonstrated that the following organic constituents are present in che groundwater: benzene, 1,2,dlchloropropane, machylene chloride, 2,4,-dinltrotoluene, n-nicrosodimechy- lamine, 2,4,6-trichlorophanol, bis(2chloroethyl)ether and chlorodibromomethane. These contaminants have been detected in concentrations above levels set in drinking water standard* (Table 1). Inorganic concamlnanCs ware also found in wacer collected from monitoring and recovery well*. The concaminants include, beryllium, cadmium, chromium, lead, mercury, nickel, iron and manganese in concencradon* above che levels sec in drinking wacar aeandard* (Tablea 2,3,4). -6-

Surface Water

In 1981, the EPA field investigation team sampled Army Creek for prioricy pollucancs. The daca indicaced che presence of organic and inorganic concaminants in che waters of Army Creek. Organics decected included phenol, bis(2- ethylhexyDphthalate, butyl benzylphthalate and di-n-butylphthalate (Table 5). Inorganics detected were aluminum, barium, cobalt, copper, iron, manganese, zinc, boron, calcium, magnesium and sodium (Table 6). AddiClonal water qualicy sampling for prioricy pollutant compounds was conducted by Weston for New Castle County in 1983 in connection with their NPDES permit application . Samples were analyzed by the New Castle County Laboratory. No volatile or extractable organic compounds were detected. The base/neutral organic compounds detected were bis(2-ethylhexyl) phthalate and di-n-butyl phGhalate (Table 7). Upstream concentrations of both compounds were greater than downstream concentrations. All values were well below their respective ambient water quality criteria. Total metals were also analyzed in 1983. Of the metals analyzed from the water samples, cadmium, lead, mercury, nickel, and iron were found at higher concentrations upstream than downstream. Copper, silver, chromium, zinc, and manganese were found downstream at higher concentrations than upstream. Cadmium and mercury were the only parameters exceeding water quality criteria upstream and downstream of the pond (Table 8). The State of Delaware, in connection with the remedial investigation at Delaware Sand and Gravel, conducted surface water sampling along Army Creek. No priority pollutants were found to exceed any water quality criteria. Sediments DNREC conducted sediment analysis in connection with the remedial investigation at Delaware Sand and Gravel (Table 9). Eight locations were sampled: six along Array Creek and Pond; one in a gravel pit pond as background and one at an intermittent stream east of Delaware Sand and Gravel. A comparison of this data with the clean stream sediments indicates that the Army Creek sample concentrations are considerably higher than those of the clean streams. Utilizing Station 7, the gravel pit pond for comparison and as a local background source, it is evident that samples taken from Army Creek and Pond have higher concentrations of all the metals detected. The iron and manganese concentrations in particular show an increasing trend in the downstream direction. Other metal concentrations peak at the pond entrance. Therefore, sediments have also been effected by the recovery well discharges. Bioassays Also in September 1973, a series of surface water and biotic surveys for Army Creek and Pond was IniCiated, Co evaluate Che affects of che recovery well discharges on Che surface water syscem. Furchermore, in che pace 13 years of discharge*, Roy F. Wescon, EPA and che SCace have Caken numerous surface and sediment samples Co decermine If high levels of contaminants exist in the Any Creek and Pond and if so, whae Cha affects of Che concamlnane* have been. Overall, che results of cha bioassays Indicaced Chae Army Creek and Pond were affecced by che recovery well discharge*, although cha Impacts were not readily discernible.

Art u u G 5 3 / -7-

In March 1986, U.S. EPA and Weston conducted split sampling for bioassay and raacrobenthos evaluations. Also well discharges were collected and composited on a weighted basis from the existing recovery wells for use in che bioassays. Macrobenthos sampling results by the EPA and Weston were basically in agreement and concluded that the the low diversity of the pollution tolerant benchic species at all stations indicate degraded water quality within che watershed. The difference in diversity and composition of pollution tolerant species Indicates that the macroinvertebraee community downstream of the pond is in better condition than the upstream station. The bioassays were conducted using fathead minnows and Ceriodaphnia dubla. It wa-s determined by EPA that recovery wells 9,28,29 and 31 exhibited chronic toxicity, while recovery well* 10,11,12,13,14 and 27 exhibited no chronic toxicity. DNREC is currently drafting a National Pollution Discharge Elimination System (NPDES) permit for the discharge of water from the County recovery wells to Army Creek. At this point It seems likely that only water in the recovery wells exhibiting chronic toxicity (wells 9,28,29,31) will be required to be treated prior to discharge into Army Pond. Water from the wells which exhibit no chronic toxicity (wells 10,11,12,13,14,27) would be permitted to freely discharge into the pond. A treatment alternative will noc be choaen, ae this time, because che final NPDES permit and tcs associated discharge limits has noc been issued. In addition, che Delaware Sand and Gravel RI/FS ha* not been completed, therefore, we can not determine Delaware Sand and Gravel'* contribution to the degradation of the groundwater, or the Army Creek and Pond at Chi* ciae. 1C 1* our intention to combine the ultimate groundwater remedial actions ae these two sites wherever possible. Also being deferred at Chi* time 1* a decision on appropriate remedial measures for the sediments in Army Pond. Further analyses of the impacts on Army Pond is required to clarify what measures if any, are required. This Record of Decision specifically deals with the selection of the source control alternative to prevent the generation of the leachate that contaminates the local groundwater. We are deferring our decision on groundwater treatment alternatives until the RX/FS ae Delaware Sand and Gravel is complete and the NPDES permit is issued. Environmental Assessmenc The remedial InvestIgaCions performed at the Army Creek Landfill Site revealed extensive ground water contamination resulting from ehe generation of the leachate at che landfill. The groundwecer and Che surface waeer are contaminated with organic and inorganic prioricy pollueanes, many of which exceed Water Ouallcy Criteria for human health and aquatic life (Table* 1-4). The major public health concern at che alee ia the contamination of eh* upper PoComac and Columbia aquifara. The major uaer of groundwacer in che area ia cha Artesian Water Company, located near Llangollen Ectataa. -8-

In 1973, New Castle County installed ics groundwater recovery system Co prevenc che migration of contaminated plume cowards Arceslan's Wellfield. Due to che success of che groundwacer recovery syscem operated by che Councy, along with che reduccion in pumpage by Arcesian Water Company, che contaminants emanating from Army Creek Landfill are noc currently threatening drinking water supplies.

Army Creek and Array Creek Pond receive surface water runoff and recovery well discharges from che groundwacer recovery syscem. However, Army Creek and Pond is rescricced for public use, prior Co its discharge to the Delaware River, one mile downstream. The effect of the creek on the Delaware river is expected co minimize due Co dilution.

Surface water bioassays have indicated that the surface water system has been effected by the recovery well discharges, although the severity of che Impacts on the aquatic life is not readily discernible.

ALTERNATIVE EVALUATION

The major objective for the remedial action to be taken at the Army Creek Landfill Site is to minimize further groundwater contamination by reducing the • leachate generated by the landfill. The requirements of CERCLA Section 104, of CERCLA 420 U.S.C. I 9604, EPA's mandate to protect the public health and welfare and the environment, determine the goals and levels of response for the site.

In an effort Co determine remedial alternatives for che subject site, feasible technologies were identified for consideration in a general response action table. Available technologies were then screened to eliminate all but the most definitive and feasible alternatives. This screening included: technical (site conditions or waste characteristics), environmental and public health, institutional, performance and cost criteria.

The technologies that have passed the technology screening process were examined further to identify remedial alternatives. Remedial alternatives were developed using best engineering judgment to select a technology or group of technologies that best addresses the problem* existing at the site co protect public health, welfare and the environment. In an effort to provide a degree of flexibility In the final selection of a remedial action, alternatives covering a range of remedial action categories have been developed. These categories are described below:

1. No action: No-action alternatives could include monitoring activities. 2. Alternatives that meet the CERCLA goal* of preventing or minimizing present or future migration of hazardous substances and protecting human health and the environment, but which do not attain all of Che applicable or relevant standards. (This category aay include an alternative that closely approaches but does not meet, the level of protection by the applicable or relevant standards.)

f. u u U D J J -9-

3. Alternatives that meet CERCLA goals and attain all applicable or relevant Federal public health and environmental standards, guidance, and advisories. 4. Alternatives that exceed all applicable or relevant Federal public health and environmental standards, guidance, and advisories. 5. Alternatives specifying offsice storage, destruction, treatment, or secure disposal of hazardous substances at a facility approved under the Resource Conservation and Recovery Act (RCRA). Such a facility must also be In compliance with all other applicable Environmental Protection Agency (EPA) standards. The broad evaluation criteria selected were: technical feasibility, public health, environmental, institutional evaluation, and cost effectiveness. Within those criteria the following factors wete considered. - Technical Feasibility •Performance •Implementabillty •Reliability - Public Health Evaluation •Reduction of Health Impacts - Environmental Evaluation •Reduccion of environmencal iapace* •Procaceion of NaCural Resource* - Institutional Evaluation •Legal requirements, Inscltutional requirements •Community Impacts - Cost Effectiveness •Capital Costs •Operation and MainCenance Coses •Presenc Worth Values •Sensitivity Analysis ANALYSIS OF REMEDIAL ALTERNATIVES

Alternate Technologies Alternate technologies Co recycle, deseroy or treat cha waatea were screened for use ae chla alee. These cechnologles Included inclneraclon of ehe wasce, recirculacion and/or treatment of the leachate, and block dlsplacemenc which consists of sealing ehe side* and/or boctoa of ehe landfill by groue injection technique. These technologies were noe chosen for several reasons. The dlsconeinuous nacure of ehe subsurface soil condleions argued againsc ehe Cechnical feasibility of grouting cha sldaa or bottom. -10-

Direct leachate recirculation or treatment was evaluated on a pilot scale in the landfill but clogging of che wells and low permeabilicy of che refuse In some areas prevented further consideration. Only incineration cechnology was retained for further evaluation.

Vote: Capital, Operation and Maintenance, and Present Worth Costs for all alternatives are found in Table 10.

Alternative No. 1 - No Action with Monitoring

The purpose of presenting a No Action Alternative is to provide a basis for comparison of existing conditions with the other proposed remedial alternatives. Under che No Action Alternative, no addiclonal remedial activities would be taken and any current activities would be terminated at the Army Creek Landfill site. This would mean that the present hydrologic divide between the groundwater contaminant plume and the Artesian Water Company Wells, maintained by the recovery well system, would be eliminated.

This alternative includes a long-term monitoring program to provide information concerning contaminant presence and concentration. Groundwater monitoring would be performed between the landfill and the Artesian Water Company wells, and within the wellfield. The primary public health concern of che No Action Alternative is the possible health risk resulting from the potential contamination of the downgradient production wells in the Artesian Water Company wellfield. Current production from these wells is approximately 2 million gallons a day (mgd), supplying the equivalent of 5,000 residences with drinking water. The effected population could increase, should the Artesian Llangollen Wellfield be shut down and the contaminants be drawn towards other wellfields in the area, including Artesian's Village, and Fairwlnds wellfields located downgradient. Of main cor- ?rn is the attenuation of organic compounds found at concentrations exceeding drinking water criteria in nine of the twelve recovery wells. Table I lists the organic compounds found in the recovery wells, the maximum concentrations encountered, and the drinking weter criteria. Under No Action, the contaminants would most likely be aCtenuated by diluCion, dispersion and absorption prior to reaching a drinking water source. However, 1C is not known at what concentration these organics will persise in che groundwacer. Therefore, a potential for human exposure by IngestIon of organic compounds in concentrations above the drinking water criteria is associated with this alternative. This alternative would not provide procection Co public health or che environment and contamination of groundwacer Chrough leaching of che contaminants would be expected to continue. Common to All Other Alternatives All of the source control alternatives discussed below would include a rigorous, Initial sampling and analysis program. Both aonleoring and recovery wells would be sampled for Hazardous Subscance Lise (HSL) compounds In order to more precisely define Che concaminancs and Chair concencracion*. -11-

All of the source control alternatives include downgradient recovery wells to control the migration of che contaminant plume. A treatment alternacive for che recovery well discharges can not be addressed at this time. The State of Delaware is in che process of issuing an NPDES permit chat would identify che safe and appropriate levels for contaminants at the point of discharge into the Army Creek and Pond. Based on chose limits, the treatment alternacive will be determined at a later date. A definite time period for phasing out the downgradient recovery well system cannot be established at this time for the following reasons: 9 Groundwater quality for organics at the site can not be precisely defined with existing data. 0 The total impact of the Delaware Sand and Gravel Landfill on the groundwater is not known at this time. * The remedial actions to be taken at Che Delaware Sand and Gravel Landfill are noc known. These actions may efface ehe quality of groundwater at the Army Creek site. The following methodology will be considered for phasing out che recovery well syscem: The recovery well system will be evaluated in Cerms of both the flow system and water quality for a period of five year* afcer che cap 1* installed or afcer che wasce 1* excavated. If primary drinking water criteria levels are noe met viehln this evaluation period, alcernace concencracion level* (ACL) will be considered. The ACL* will be baaed on an evaluation to define if sufficient attenuation will be achieved downgradiene of Che Army Creek Landfill, so that drinking water criteria level* will be mat ae any potential receptors. These ACLs will be applied at che recovery wells or che property boundary. When the ACLs are met, the recovery well syscem could be phased out. Alternatives that Include a cap may encroach on che 100 year floodplain at the south end of the sice. The floodplain exeenda Co approximately the ten foot contour. During design, detailed survey* and design evaluation will determine if any portion of the cap muae extend to this area. Suitable measures Including gabions or rip-rap may be used to protect che cap and minimize encroachment in Che floodplain. Alternative Ho. 2 - Downgradiene Pumping Alternative No. 2 consist* of a series of downgradiene pumping walls co recover concaminaced groundwater and conerol lea algration. In 1972, when ic was discovered that leachate had eneered the underlying confined aquifer in cha Potomac Formation and had contaminated a nearby domaetic wall, we*eon was reeainad by New Caatle County to investigate Che extent of ehe problem and propoae potential solution*. Prelialnary hydrogaologlc investIgationa conducted by Weaton indicated Chat Che laachaea had concaminaced a aubatantial volume of che upper Poeoaac aquifer and chat contaminated groundwacer waa moving in che -12-

direction of the Artesian Water Company's Llangollen Wellfield in response co both the natural groundwater gradient and the pumping effects of the Artesian wellfield. The nearest Arcesian Water Company well was located about 1,600 feec from che edge of che concaminanc plume.

Based on preliminary hydrogeologic invescigacions, a contaminanc recovery and monitoring program was designed and implemented in 1973 as an initial seep Cowards an eventual solution to the problem. The recovery program was designed co achieve the following objectives:

0 To control the migration of contaminants towards Artesian Water Company's wells and to contain them in an area closer to the landfill.

0 To create a groundwater divide between the Artesian wellfield and che contaminated zone such that the groundwacer flow in the contaminated zone could be reversed and the contaminated groundwater between the recovery wells and wellfield would move toward the Army Creek Landfill.

* To recover contaminated water and restore the aquifer water quality. 0 To monitor the water quality and water levels in the area and evaluate the effectiveness of the recovery program. 0 To develop feasible leachate treatment and disposal methods until some type of permanent solution to the problem urns determined.

As a result, a large number of observation and recovery wells was constructed. While the observation wells were constructed in both the shallow Columbia sediments and the underlying Potomac aquifer, the recovery wells were constructed only in the contaminated zone of the upper Potomac aquifer, which is the aquifer source used by Artesian. The Initial recovery well system consisted of eleven recovery wells RW-1, 2,3,4,5,6 and wells 27,28,29,31 and 53 (Figure 3). In 1977, the data collected during the initial operation from 1973 to 1977 wa* evaluated. The following conclusions were made at that time based on the evaluation: * The recovery wells have been successful in containment of the contaminated groundwacer plume within the groundwater flow south of the Army Creek Landfill. * A groundwater divide has been developed between the Artesian Water Company's wellfield and the concaminaced zone of groundwacer. The groundwacer flow in che concamlnaeed zone between the landfill and che Arcesian wellfields has been reversed cowards che recovery wells and cha Army Creek Landfill. * Recovery walls RH-1, RW-3, RW-4, and RW-S continued Co "pull beck' che concaminancs co as far as chair presenc locaciona; chase recovery wells could be phased ouC of che syscem in scages by reducing cheir pumping race*. -13-

0 It would be necessary to monitor the water quality in the vicinity of recovery wells RW-1, RW-3, RW-4 and RW-5 more frequently than usual when their pumping rates have been reduced. This would assure early detection of any deterioracion in water quality caused by reduced pumping rates. 0 Ic appears chat most of the inorganic contaminants are discharged into che upper Potomac aquifer in an area of the landfill north of recovery wells 27, 28 and 29 and in che southwest corner of the landfill. * The total pumping rate of the recovery wells was approximately 1.5 million gallons per day, which is about 7.5 times more than the average daily rate of potential leachate production. Leachate would be recovered more efficiently if the wells were located within and closer to the landfill. " Incrustation ha* caused a significant problem requiring frequent rehabilitation of the recovery wells. To control the incrustation problem, the pumping rate* of the existing recovery wells should be further reduced by about 50 percent. * When RW-1, RW-3, RW-4 and RW-5 have been phased out of the recovery program, more recharge will be available for Artesian Water Company's wells, It was therefore recommended that new wells RW-10, RW-11, RW-12, RW-13 and RW-14 be installed closer to the landfill such that leachate and contaminated groundwe.cer could be recovered more efflcienely. This was also recommended by che Round Table Conference in 1977. In May 1982, the effectiveness of che modified downgradiene pumping system was evaluated through a series of pump tests performed on che new recovery wells, RW-10, RW-11, RW-12, RW-13 and RW-14. The conclusions and recommendations generated as a result of the pump tests resulted In the phasing out of recovery wells RW-2, RW-3, RW-4, RW-5 and RW-6. The currenC downgradiene pumping system includes RW-14, RW-13, RW-12,31,29,28,27, RW-1, RW-11, RW10, and RW-9 (Figure 3). The current system has maintained the groundwater divide necessary to intercept contaminated groundwater. The clogging of well screens and discharge linea by iron precipitate is a continuous problem Chat ia addressed through a regular program of well rehabilitation and pump repair. During the period of June 1982 through April 1983, at lease one well was off-line for maintenance, repair or rehabilitation during any given aonCh, .wieh Che excepdon of June 1982. Since che phasing ouc of well* wieh eh* poreae performance, a biannual ma1neenance program has been established Co treat aad rehabillcaca ehe cwelve operaclng wall*. Maincenance and replacement of parts have been performed aa pare of ehe maintenance program. Since che recovery wall syscem Is already in place and oparacive, chare Is no implemencadon cime neceaiary for this aleernaclve.

A R G u G 5 k -14-

Sampling and testing performed at che Artesian Water Company's wellfield and concentration gradient maps of Che area have indicaced chat the downgradiene pumping syscem along with controlled withdrawal by Artesian has been effective in containing the contaminated groundwacer plume chrough che creacion of a hydrologic divide between the landfill and che Artesian Water Company's wellfield. Alcernacive 2 has cherefore been proven co have concained contaminated ground- water. By controlling the contarainaced groundwacer che pumping syscem has prevenced che possible abandonment of the upper Potomac aquifer as a source of water supply in che production wellfields near the landfill and reduced the public health risk that could have resulted if the contaminated groundwater plume was not controlled. Alternative 2 does not, however, address the source of leachate entering the Potomac aquifer or the pathways through which water enters che landfill resulting in leachate production. Precipitation infiltrating through che landfill surface and groundwater Infiltration through the northwest side of the landfill from the Columbia aquifer will continue under this alternative. Therefore, leachate migration into the Columbia and upper Potomac aquifer will continue should Alternative 2 be implemented. This alternacive doe* noc attain all applicable and relevant public health and environmental standards as defined by CERCLA and RCRA. Alternative No. 3 - Downgradient Pumping and Landfill Capping Alcernacive 3 consists of the downgradiene pumping program evaluated under Alternative 2, and includes capping th« landfill with a multi-layered cap. The multi-layer cap system represents a recently developed cover technology that is gaining widespread use as an infiltration control strategy for waste containment or in-place closure. The multi-layer cap system performs the basic functions of minimizing infiltration into the waste site; directing and transmitting percolation and gas migration away from the site; and providing a final cover for the site and growth medium for vegetation. A typical multi- layer cap system, as shown on Figure 5, consists of the following three layers: a) Uppersoll layer. A top soil and native soil layer, typically placed co a depth of about 12-24 inches. This layer serves to support vegetation, provide a cover for the drain layer, and divert surface runoff. b) Middle drain layer. A graded layer of porous flow zone material (e.g., sand, gravel, geogrid) to act as a drainage medium. This layer is typically placed to a depth of about 18 Inches. c) Cap layer. A compacted layer of fine-grained soils of low permeability designed Co divert Infiltration chat ha* percolated through che upper soil layer. Thi* cap layer 1* typically placed Co depths of about 18- 24 inches. The successful multi-layer cap syscem Incorporaces Che use of low permeability maCerials co provide a surface seal over che concaminaced area. A zone of high -15-

permeability materials, such as graded gravel, aggregate, and drainage geotexciles, is typically placed over a cap layer co enhance lateral movement of wacer chac percolaces chrough che upper soil layer. The upper soil layer provides che following (a) A soil cover co promote runoff. (b) A protective cover for the drain layer. (c) A medium for growth of vegetative cover. The vegetation not only stabilizes the cover system from possible damage due to wacer or wind erosion, but also contributes to moisture loss through evapotransplracion. Several major advantages of the multi-layer cover system as compared to a standard native soil cover Include the following: (a) A protective soil layer is placed over the cap layer; the cap is not directly exposed to excessive damage due to weathering, cracking or root penetration.

(b) A drain layer serve* to divert additional percolating water so it does not eventually migrate into che underlying waste material. (c) Possibl* slumping of che Copsoil and upper soil layers is minimized. Calculations using hydrologic simulation modeling show that che multi- layered cover system can divert greater than 90 percent of the precipitation falling on the site. Since the cover is constructed of netural materials, it is expected to remain effective over the 30-year evaluation period. Final design studies will be used Co determine the material types and specifications for che number of layers and thickness of the final cap system. Any system installed will comply with the RCRA cap requirements. Alternative 3 provides the same health benefits aa Alternative 2 by containing the contaminant plume chrough che creacion of a hydrologic divide between the landfill and Che Arcesian Water Company's wellfield by downgradient pumping. The recovery pumping program in place at Che Army Creek Landfill has proven co have conealnad concaminaced groundwacer close Co che landfill. By controlling che concaminanc plume, Cha pumping system has prevented che possible abandonment of ehe upper PoComac aquifer aa a source of wafer supply in che production wellfield* near Cha landfill. This alternative aeeaina all applicable and relevanc public health and environmental standards aa defined by CERCLA and RCRA. Alternative No. 4 - Downgradiene Pumping, Landfill Capping, and Upgradienc Concrol* A. Non-phased Approach - The non-phaaed approach eo Alcernacive 4 would include Cha conetnuatIon of ehe downgradiene pumping program and cha simultaneous -16-

conscruccion of che final cap system and che upgradienc groundwacer concrols (Figure 6). This approach Co Alternative 4 provides additional immediate measures to further mitigate che environmental impaccs of che landfill as compared to Alcernacive 3. The upgradient controls would intercept and significantly reduce the groundwater entering the landfill along che norch- wescern side, chus reducing che potential volume of leachate produced. The flow of groundwater into the landfill along the norchwescern side has been esciaaced ac 25,000 gpd aa compared to 4,000 gpd of precipltacion infilcracion. B. Phased Approach - The phased approach to Alternative 4 involves cwo phases. Phase 1 would include installation of the final cap system with continuation of che downgradient pumping system. The effect on the groundwacer quality as a result of capping the landfill would then be monitored and assessed prior to initiating Phase 2 upgradient controls. It is possible that although a significantly greater volume of groundwater passes through the site than does precipitation, the refuse that comes in contact with the groundwater has already had much of the contamination leached after almost seventeen years in a saturated state. Monitoring has also shown that the groundwater table elevations have dropped over the past twelve years due to the additional pumping, resulting in a lesser quantity of refuse that is saturated. Precipitation, on the other hand, percolates through the entire refuse stratum, allowing for more contact with a greater volume of landfill material. Following an evaluation period of 5 years after the cap is installed, the need for upgradient groundwater controls to reduce leachate production would be determined. This determination would be based on the evaluation of the monitoring well water levels, pumping rates and water quality. Both the phased and non-phased approaches include surface management measures and gas venting as part of the construction of the cap system. The technical evaluation of the downgradient pumping program has been performed under Alternacive 2, and Che evaluacion of Che multi-layer cap system under Alternative 3. Final design analysis will be used to determine the material types and specifications for the number of layers and thickness of che final cap system. The analysis for this alternetive will therefore concentrate on evaluating the upgradient controls. An upgradienc pumping network is used here for evaluation purposes only. The final upgradienc concrol (pumping or trench) would be determined during Che design phase. Ic 1* anticipated that less pumping, both in quantity and duration, by the downgradient recovery well system would be required as a result of capping the landfill. Upgradienc concrols should further hasten groundwacer cleansing, reducing Che time the downgradient system has to be operated. The arrangemenc and number of recovery wells necessary co prevent the lateral inflow of groundwacer inco cha Army Creak Landfill would be contingent upon several of the following factors; Che volume of inflowing wacer, che depch co which cha wacer cable mu*C be lowered, and Che abillcy of ehe Columbia aquifer to transmit water. -17-

To intercept the inflowing groundwater and lower the water table wichin che landfill, Weston determined that five recovery wells, spaced at 320-foot Intervals, would be needed. The wells could be located directly south of the railroad cracks along the northwestern boundary of the landfill (Figure 3). To ensure maximum drainage from che Columbia aquifer, che depth of the wells should extend co che base of che aquifer (25 to 30 feet).

An evaluation of various pumping rates estimated that a discharge rate of 20 gpm per well would provide maximum drainage of the Columbia aquifer without exceeding the critical well drawdown limits. The pumping rate of 20 gallons per alnute(gpm) at each of the five wells would remove approximately 144,000 gpd of groundwater, creating a hydrologic drain for the groundwater enroute to che landfill. The drawdown Influence from the pumping wells would lower the wacer cable wichin che refuse. Upgradient pumping would essentially dewoter a major portion of the refuse, leaving only a traction of the total waste volume saturated near the base of the Columbia Formation. The water level in Army Creek could poteneially impacC che dewatering influences of the upgradienc wells. If che cumulative drawdowns from the five recovery wells lowers che water table below ehe water level of Army Creek, chen surface wacer flow Into che Columbia aquifer could be induced. This would eventually create a steady-state condition between che water levels In che wells and the stage of the stream. Ac this else, Che variation in the elevation of the surface water In Army Creek 1* unknown, and the effect of che scream on che maximum wacer cable drawdown* cannot be determined. Alternacive 4 provides ehe same haaleh benefits •• Aleemaeive* 2 and 3 by containing the contaminant plume chrough Che creacion of a hydrologic divide between the landfill and the Artesian Water Company1* wellfield by downgradient pumping. Alternacive 4 provide* further measures to mitigate the environmental impacts remaining after the implementaeion of the downgradient pumping and landfill capping included in Alternative 3. Under the non-phased approach to Alternative 4, upgradienc controls will be installed at the same time che landfill is capped. Boch paehways of infilcration into che landfill would, therefore, immediately be addressed. Poceneial leachaCe production should be significantly reduced aa a resulc of these actions. 1C 1* therefore anticipated that groundwater cleansing would be further hastened under Alternacive 4. The phased approach would allow for a period of monitoring and assessment of the effeceivene** of capping Che landfill on groundwacer quality. Following an evaluation period of 5 year* afcer che cap 1* insealled, che need for additional measures Co reduce leachaee production would be determined. This decision would be baaed on an evaluaeion of wacer levels and wacer quality ae che Army Creek Landfill. This alternative accaina all applicable and relevant public health and environmental standards aa defined by CERCLA and RCIA. Alternative 5 - Downgradient Pumping, Pareial Removal and Landfill Capping Alcernacive 5 conalae* of Che downgradiane recovery well syscem also included

A R U U U J v L> -18- in Alternatives 3 and 4, c'le excavation of the landfill ref-.i** in tho VP,: section, and inovement of the excavated refuse on che eastern serein. T'->e eastern section would Chen be graded and capped wieh a ~iu 1 1 i-lavered : .vj s and the wescern -seecion b.ic' s i rf ace run -off and vegetated. Eros I in a .id run-o f f rontrols wml d ^e ^c i-i excnvaced and fill arens. The sat irat->d refuse in the western sert ii-. require "^ev.iter ing" or draining as It is excavated and would be Mxed '.«-i -tryer refuse to he placed and co^pact2d ->n the eastern section of t^e 1 3-. A cO'Tibin it ion of draining/pulping of free liquids from cht» saturated r-r'u and upgradienc controls would be required for the dewaterlng process. T;. provides a jraphical presencacion of Alternative 5.

This alternative will remove one of che sources of concaninac ITI of the aquifer and subsequently the upper Potomac aquifer by che excavation of the wescern seccioa of the landfill. Field infonadon suggest-; f.hac groundwacer is infilcracing che refuse lacerally in this section of the landfill.

This alcernaclve ilso addresses Che precipt Cation inf ilcriclon through :^e r«?-nov,il and redeposlclon of refuse co che eascern sev-.cion of che landfill -/hL;:h would Chen be capped wieh a mulci-layered cap system. The mule l-layered cip syste- was evaluated in Alternacive 3. Alcernacive 5 would be effeccive in addressing the paChways of Inf I Icracion and reducing the potential volume of leachate produced frotn an estimated 29,000 gpd (25,000 gpd groundvater infiltration plus 4,000 gal/day of precipitation inf iltracion) Co an osclmaced 2^0 gpd ( preclpl cacion infilcraclon chrough nultl-layered cap syscen). Source renoval would provide an effective long-term solution to groundwater .-ontaminacion at :he sice. The useful life of che nulti-layered cap sysc .-i would depend on che esc abllshnenc of .a -naintenance progran chat would na.'.'italn a prjper \/egeta:-»d cover and Inta^ricy of Che cap. A properly conscru::

Once che vegetation on the fluitl-layered cap system Is established it would require routine regular maintenance. The entire vegetated area should be "lowed once or twice a year to minimize the potential for growth of deep-rooted vegetation. The surface cap on the eastern section should be periodically Inspected to assure continued Integrity of the capping system. Cracking, erosion damage, and differential settlement damage would require repairs.

Two of che major concerns resulting from the excavation of the western section of the existing landfill include the following:

* Dewacerlng of Che western section would be required before che saturated refuae Is excavated from below che wacer table. Upgradient controls similar Co Che syscem outlined under Alternative 4 can be used to lower the water table below the refuse. Complete dewatering may Include the construction of drains and sump controls, but It is anticipated that most of the free liquid would be removed by the upgradient controls. The discharge from the upgradlent conerols could possibly require treatment. Since th* duration of pumping (If used) will be short-Cerm (time required co excavate the wescern section), the mosc cosC effeccive treatment

A ii u U U u -19-

option could possibly be discharge to the local waste treatment facility (Wilmington Waste Wacer Treatment Plant).

° A potential slope stability problem could result between the eastern section and che wescern section as excavation of the western section resulted in deep cuts into landfill refuse. The excavation should proceed in an "area" type manner to minimize deep cuts and possible stability problems. Final side shapes after backfilling in the eastern section should be limited to a maximum ratio of 3 horizontal to 1 vertical (3:1) to ensure slope stability.

Excavation of the saturated refuse would be accomplished using either backhoes or draglines working from the top of the working face. If a pocket of non- refuse or potentially hazardous wastes has been identified, special excavation and handling procedures would be initiated. All of the refuse, with the possible exception of waste requiring special handling, would be loaded onto dump trucks. These vehicles could Chen haul che refuse on a temporary access road along che north side of the landfill running parallel to the existing railroad. Free liquid from Che tranaportation of che refuse would therefore be contained within the existing landfill area. Extensive odor control would be necessary wichin and around ehe perimeter of the excavation site for the dump trucks. After the western section had been completely excavaeed and backfilled with a clean soil fill, cha easeern secclon would be prepared for the final capping. The cap would be placed over ehe incermediace soil cover and utilize a multi-layer design. The multi-layer cap system would significantly reduce precipitation infiltration. Erosion and sedlmentacion concrols would be initiated until a proper vegetated cover is established. Gas venting and surface management measures will be Installed during the construction of the cap system. While Alternative No. 5 represents a potential safety risk to the construction workers, due to the unknown types of waates and conditions which would be encountered during excavation, proper safety protocol would reduce the risk. Alternative 5 providea Che same health benefits as Alternatives 2, 3, and 4 by containing che concaminanc plume chrough the creation of a hydrologic divide between the landfill and cha Artesian Wacer Company's wellfield by che existing downgradiene pumping program. Alcernacive 5 provides basically che same environmental benefits aa Alcernacive 4 bue addresses che groundwacer infiltration condition In eh* wescern porelon of che landfill by elialnacing che source of leachate generaCion chrough Cocal removal of che refuaa in che wescern seccion. Groundwacer cleansing would be hasCened by cha elimination of cha source of contamination. Capping Che eaacarn seccion wieh a aulci-layer cap would signifi- cantly reduce precipicaclon infiltration which would further hasten groundwater cleansing.

During excavation, odor and vector probleaa would likely occur in addition co che need Co handle draining wacer from saeuraced refuaa. Laachaca pumped during dewaeerlng ope radons before che sacuraeed refuse is excavaeed would need co be collecced and creaced. -20-

This alternative attains all applicable and relevant public health and environmental standards as defined by CERCLA and RCRA.

Alternative 6 - On-sice Incineration and Downgradiene Pumping

This alcernacive consists of Che conscruction of an incinerator and power generacor facilicy adjacent Co che subject site, excavating and incinerating che wasce, and backfilling che ash residue on-siCe. In order for chis alternative co be feasible, the excavated landfill wastes at the site would need to be mixed wlch raw-solid waste from nearby communities or other fuel to produce a combustible mixture. Otherwise, the fuel requirements for burning the wet waste would be very excessive. Excavation of the saturated material would require dewatering. This could be achieved by upgradient pumping or pumping directly-from the excavated area. The discharge from the dewatering operation could require treatment. This alternative would include continued downgradient pumping to assure chat contaminated groundwater did not reach the Artesian Water Company's wellfield. A long-term groundwacer monitoring program would determine when che downgradient recovery system could phased out after the landfill had been removed and incinerated. Alternative 6 would provides basically the same public health and environmental benefits as Alceroaeives 4 and 5 through downgradiene pumping and removal of che source by excavation and Incineration. Dry refuse or other fuel would need co be transported to the site and mixed with the saturated waste to make it burnable. Air pollution control devices required under RCRA would reduce che release of contaminants into the air. Incinerator ash and residue would be backfilled on-slte only in areas above the groundwater table and eventually capped. Dust, odor and drainage of liquids from the saturated waste are problems associated with the excavation of landfill refuse. Other environmental and health concerns would he associated with the transport of dry refuse to the Army Creek Landfill site. These concerns include noise and dust from transportation and vector problems. Measures such a* vector control and site access routing, would be initiated to mitigate these problems. Construction activities during excavation could affect wetlands habitats through noise, surface water diversion practice* and du*C. Drainage could also have an effect, if noc controlled. On-site incineration would be required Co meet the technical requirements of RCRA. In addition to RCRA requirement*, the remedy would need co comply with other applicable Seace and Federal requirement* bue would noc need a permit. A monitoring program would also be a mandatory part of the incineration process. Significant public opposition could be expected Co chis alcernacive. This alternacive aCCalna and/or exceed* applicable and relevant public health and environmental sCandards aa defined by CERCLA and RCRA. Alcernacive 7 - Off-«iee Di*po*al by LandfillIng ae an Approved Sice and Downgradiene Pumping This alcernacive concise* of compleeely removing che landfilled wasce by

ARGuObb i -21- atandard excavation methods and disposing of the waste in an approved off-sice facility. Upgradient pumping has also been included for the anticipated dewacering of che saturated material in the bottom of the western part of the landfill prior co excavation. The landfill area would be backfilled, following complete excavation of the waste material. This alternative would eliminate a source of leachace generation (refuse) and thus eliminate the addition of contaminants to the groundwater. This alternative includes a downgradient pumping program. Monitoring of the recovery system will determine when the system can be phased out after complete removal of the landfilled wastes. Alternative 7 would provide basically che same public healch and environmental benefits as Alternatives 4, 5, and 6 through downgradiene pumping and che complete removal of the source of contamination by excavation and disposal in an approved off-site landfill facility. These actions would prevent direct human exposure and accelerate groundwater cleansing as do Alternatives 4, 5, and 6. Dust, odor, and noise problems would arise from che excavation and Tiauling actions contained in this alternative. The off-site facility would need to be a RCRA permitted landfill to assure that potential environmental Impacts at the new sice are minimized. Commercial disposal facilicies aust meet scringene analytical, RCRA, and State peralccing and compliance scandarda. Uaing off-«ic* facilicle* also would require that the Deparemene of Tranaporcaeion requlremene* are mac. Opposition could occur from Cha Scace receiving chis large quaneiey of wasce (approximately 2,000,000 cubic yards). Off-sice facilicies could also be reluctant co accept this large quaneiey of waste. This alternative accains and/or exceeds all applicable and relevant public health and environmental standards as defined by CERCLA and RCRA.

RECOMMENDED ACTION (Table 10) Section 300.68 (J) of ehe National Contingency Plan (NCP) states Chat che appropriate extent of remedy shall be determined by ehe lead agency's seleccion of che remedial alternacive which che agency decermines is cost-effective (i.e., the lowest cose alternative that is technologically feasible and reliable) and which effectively mitigates and minimizes damage Co, and provides adequate protection of public healch, welfare, or che environmene. Based on our evaluation of the cose effecdveness of each of cha proposed alternatives, of the comments received from ehe public, and Information received from ehe Delaware Department of Natural Resources and Envlronmencal Conerol, we recommend that cha phased approach Alternative 4B be implemented at cha Army Creek Landfill Sice. Thi* alternative include* downgradiene puaping wieh monitoring, landfill capping and possibly upgradienc controla. Thia alternative will reduce che public healch riak by poaaibly coneainlng Cha contaminant plum* through Che downgradiene recovery syscem. This altemaeive will alao control precipicacion infilcraeion Chrough the landfill surface with a multi-layered cap. Groundwacer infilcraeion chrough che northweat side of che landfill from cha Coluabia -22-

aquifer will be controlled by upgradient measures; if necessary. Leachace migration into the Columbia and upper Potomac aquifers will be reduced. The upgradient controls (pumping or an interception crench) may be inscalled following an evaluation period of up co 5 years afcer che cap is installed. This decision would be based on an evaluation of water levels and water quality at che Army Creek Landfill. An addicional component of this alternative is a well monitoring program.

At chis cime, the selection of a groundwater treatment alternacive has noc been made and will be the subject of a future decision document. In particular chis decision has been delayed because the final NPDES permit has not been Issued and the Delaware Sand and Gravel RI/FS has not been completed. It is EPA's intention to combine the remedial actions at both sites where possible and cost-effective. Also being deferred at this time is a decision on appropriate remedial measures for sediments in Army Pond, that decision will Be made at che same cime as groundwater treatment is considered and after further analysis is accomplished regarding the actual impacts on Army Pond. Operation and Maintenance At least, quarterly inspection and maintenance will be required during the operation of the downgradient and upgradient controls. Wells will be inspected and maintained to insure their continual funccioning. Maincenance of che multi-layered cap will be required to ensure that the cap is functioning properly in preventing the infiltration of stormwater into the landfill. Vegetaelon loss, erosion, cracking or other cap disturbances will be corrected. Consistency with Other Environmental Laws Alternatives were examined in light of relevanc Federal, state and local environmental program requirements and in light of all RCRA and CERCLA require- ments for the closure of hazardous vase* landfills and for disposal of excavated concamlnants in offsite hazardous waste facilities, including landfills and incinerators. The recommended action meecs all applicable and relevanc public health and standards as defined by RCRA and CERCLA. Evaluation of AlCernaClves Noc SelecCed (Table 11) The No-Accion AlCertfaclve No. 1 with monitoring was not selected since it would not control the source of contamination and would allow further degradation of groundwacer. ImplemenCaCioo of cha No-AcClon alcernacive would mean that the present hydrologic divide between the Army Creek Landfill site and Artesian Water Company's production wells would no longer exist. Therefore, a potential for human exposure by Ingescion of organic and inorganic compound* In concentrations above the drinking wacer cricerla would exlsc. Thi* aleernacive doe* noc provide protection Co public healch and Che environmanC. -23-

Alternacive No. 2 involves downgradient pumping with monitoring. Although this alternative would reduce the public health risk by containing the contaminant plune chrough pumping, ic would noc, however, address the source of leachace encering the Potomac aquifer or the pathways in which water enters the landfill resulting in leachace production. Precipitation infiltration though the landfill surface and groundwacer infiltration through the northwest side of che landfill from che Columbia aquifer would continue under chis alternative. Therefore, leachate migration into the Columbia and upper Potomac aquifers would continue for Alcernacive No. 2. Alternative No. 3 would involve downgradient pumping with monitoring and landfill capping. Although this alternative would reduce the public healch risk by containing the contaminant plume through pumping and control precipitation Infiltration through the landfill surface, it would not address groundwater infiltration through the northwest side of the landfill from the Columbia aquifer. Therefore, leachate migration into the Columbia and upper Potomac aquifers would continue for Alternative No. 3. Alternative No. 5 would involve excavation of the landfill refuse In the western section, and disposal of the refuse on the eastern section, downgradient pumping with monitoring and capping. Alternative No. 5 would address the groundwater infiltration condition in che wescern portion by eliminating the source of leachate generation through total reaoval of ehe refuse in che wescern seccion of ehe landfill. This alcernacive waa reJecCed because ic provides the same benefits as Alternative No. 4, but coae* twice as much ($37,930,000 vs. $15,290,000), and would be more difficule co implemene. Alcernacive 6 would involve on-sice incineration and downgradiene pumping. This alcernacive would provide basically che same public healch and environmental benefits as Alternative 4 through downgradient pumping and removal of the source by excavations and incineration. This alternative was rejected because it would provides the same benefits as Alternative No. 4, but would cost 7 times ($108 million vs. $15,290,000) as much and would be more difficult to Implement. Alternative 7 would involve the complete removal of the landfill and down- gradient pumping and monitoring. Thi* alternative would provide basically the same public healch and environmencal benefits aa Alternative 4 through down- gradient pumping and removal of che source. This alternative was rejected, because it would provide* eh* same benefits as Alcernacive 4, buC coses 15 times as much ($243,000,000 vs. $15,290,000) and would be more difficule Co implemene.

U LOCATION OF ARMY ,.. NEW CASTLE COUNTY SCALE:l"«2000 OfLAMfAM SAMO * elUMEL

am (suit aMif • oa ettu. falfcA '

ARMY CREEK LANDFILL- SITE SKETCH NEW CASTLE COUNTY, DELAWARE SCALE; i"»iooo' : \i NUS I I «• ItGtNO aj 6 INDICATES LOCATION OF RECOVERY WELL *) 64 INDICATES LOCATION OF POTOMAC WELLS (DEEP) • BIB- INDICATES LOCATION OF COLOMBIA WELLS (SHALLO"!

ARTESIAN WATER CO WELL FIELD

o ARJvl^REEKJLANOFJLL^NEW CASTLE COUNTY, DELAWARE c a LOG AT ION OfJvlONrrORING, PRODUCTION AND RECOVERY WELLS m SCALE: |"= 1000' IMUS CORPORATION TABLE 1

ORGANIC COMPOUNDS IN RECOVERY WELLS EXCEEDING DRINKING WATER CRITERIA*

Max . Cone . C C la Wall Paraaetar (ug/l) fig ^f FW-1 Betvzene 12.0 b 1 , 2T-dichloropropane 40.6 s!o Methylene Chloride 32.0 0.19C Bf-10 2 , 4-dinitrotoluene 44.0 O.lld . N-nitroaodiaethylaaune <10.0 O.OQ14a 1 , 2-dichloroathane 51.0 5.0* FN-11 Benzene <10.0 5.0* FW-12 Benzene 10.3 1 , 2-dichloropropane 25.1 Methylene Chloride 21.2 0.19sio*C 2 , 4,, 6-tr ichlorophenol 3.0 1.8* Bis*! 2-chloroethyl ) ether <10.0 0.03d FM-13 1 , 2-dichloropropane 26.8 6.0b Methylene Chloride 21.3 0.19^ Bix ( 2-chloroethyl ) ether 46.0 0.03d Benzene 37.0 5.0* FM-14 Bis ( 2-chloroethyl ) ether <10.0 0.03d 2 , 4-dinitrotoluene 38.0 O.lld 28 Benzene 40.0 5.0* 29 Benzene 45.0 5.0* 31 Benzene 150.0 Methylene Chloride 16.3 0*.19^ Chlorodi or oaoaethane 19.2 0.195 2,4-diaitrotoluene 116.0 O.lld

* - All laboratories (1983-1985) a - Proposed Primary MCL (BPAt 13 Hovaabar 198S) b - Proposed BMCL («PAf 13 Sovaabar 1985) c - Water Quality Criteria for Huaen Health (Fish and Drinking Water)i concentration of total haioaethanea (CMA) - d - Water Quality Criteria for Huaan Health - Pish and Drinking Water (CWA) e Water Quality Criteria for luaan Health - Adjusted for Drinking Water (CWA) TABLE 2

..J.:* l I 4411J. Ottl.WMI I . ji i, Oullcy IMI

•.am* *.MI • OU14 • .010"

o.uu •••lit O.MM 0 (UM • .«*"

O.OOM •.Ml) • .MM 0.0104 I.I1

0. O.OU4J Mjroury • tun o.c O.OMI s-sw •.Mtt

•.001*

O.Otti

Stao ».2M •.*• 0 OM O.fcu

It* C«Ml« County l*lnr«to Pricing MMMC iCMk) Prl«r/ MX IBM. II Hwwrfur IMil CiltarU faw Oclnftlai| Mti«r Only ICMI Crlt«(i« 4CMI ict MCI. !•>*. 1 1 NuMMkir (Mil C7! C~J c.n en TABLE 3

lAMVIU. MiH OUHU. OUMHUOi uuttftMic MUM OUM.ITV

Uinking ...ul .. . W.I :C (•/U SM-1 M-) flf-4. «J*-4 .««-» ff-10 >**-!! MM-tl BM-J4 II CfUcii* I'l I Id la

«.M*2 S.MS S.MM 4.M47

SuryllitM

•.•214 S.M4 S.M4 4.MA* S.OM4 4. Mil •.Mli 4.M21 «.M14 4.00M 0 OOU U IUU

IIM~

• .Mil •.Mil <*.MI 4.0044 •.M14 S.Mii 4.4042 4.M17 4.M11 4.MM 4.MM O.M) 0 liUc

Mtfuury S.MIS S.MI4 S.MI4 4.M47 NH 4.0M7 S.M1I 4.M24 4.M2) «.MI «.OO4 Ml

NldMl S. 11* S.MS •-254 • .12* 4.014 • .MS S.IM •.MS 0.254 •.•&• 4.IM 0.0024

&4 S.4UH <«.M2 <«.M2 <«.M2 •.•247 <«.2M

•I I Mir S.Sttt 4.4S27 • .MM •.Mil 4.004) • .MM «.M4» 4.M17 4.MH 4.4044 «.M44 4.OH4

•SMlltw <«.MI

S.SM •••!• • •«• 4.414 4.414 4.424 4.424 0.429

i.44 4.M 14.4 II.» 4.4 14.4 47.4

• .42 I > » 0.4t 4.M l.M a.I* 4.7* 4.47 l.W ••* ' CMU Oainty of C1 c - No Mwalt* ttittr Qtfrilty lot MUMH HiMlUt ' Pith Mtt^r tCMI C-- Id. Cn Cn tUtt€ Ol*"y *»r SIMM MwlUt - *( ION) •a. W4O. 1ST*. U Ma/MrtM' LUlt TABLE It

MM Owlle, DtJ.ii.4K Cx»»t MMef Quillly S^M.Htcc 1*44 &M|«llii>J

III lurtll^j 'NU 1 ii .- M..I C.«K...rtt*.|.JM 1*211 44 Mull 44 Mull 24 Mull 24 Mi-.ll 10 IM •» U« II Mull fi *M.-, W.I.I Hucoveiy Cl tluf IA I'l II i.i t.i A4 . • *.,l»y vO.OO> <4.y^ <0.004 4.M7 <0 004 <0.0»4 .O.OU4 <0.(U4 0 14k Ik

Aff*t*il*; v4.002 <4.M2 <4.00J <4.M2 <4.M2

ft.yltkuB 0.020 <4.Mi <4.0U4 <0.004 <0.004 vO.OU* 0.0044 6. 244 <4.M4 <4. 144 <4.I44 <4.IM

e 0«.» 04* 4.444 <4.444 4.1*4 <4.4M <4.4M <0.040 <0.040 I.I* 0 4 I.M.I O.IM 4.421 4.414 4.774 4.41* <4.M2 0.010 <4.001 O.Obo" O.I4I>':

b »«..iMY*' 4-422 <4.4M2 <4.M42 4.4442 (4.4442 <4.0M2 <0.0002 <4.002 0.002 0 OU-,"

d e Mivtal 4.144 <4.4M <4.4M 4.M1 <4 454 <4.4U <0.040 <4.044 0.0l44 l.n

b : SJxtlMB <4.M2 <4.M2 <4.M2 <4.M2 4.MI <4.M2 <4.001 <4.001 O.OIO 0 U/

b e SllMMT <4.M5 <4.Mi <4.4M <4.44i <4.Mi <4.M4 <0.004 <0.004 0.04 0 |

d C Y 1U.lt !«• <4.4I4 <4.M» <4.4I4 <4.«4 <4.4I4 <4.4I4

• • '*.-!, wl b*«l U» fc.Mi«| tl*. x- 2 l?£?*M£j£*'£Xi.t i | 1 —. ^ a UMIW QMkllty Oltvrl* l»r IkHMi lb«lth - *)>••<. «J tat (M inking MAIM Oily (0*» Criiarl« fur Ol*dur>jMI lOMI »tlc - riah Md OflMkli•y M«w IUMI r- -, * rr^uNAi n*a. IIM, n'no»<»iii» (CM*I O - Amy Creek Landfill New Castle, Delaware Amy Creek and Pond Mater Quality BPA/F1T Sanpllng 9-11 November 1981 Orxjanic Concentrations (u|A)

w g 3 4V "^ tJ J 5i *S ~KPM *o c 8St"£ Station I « iJiJ s^ I (Mt. 13) ND ND ND ND ND ND ND M) NL> M)

II (Mt tracks) * W) ND ND M) ND <3 III (nr. W-9) ND ND M) ND (diacharga) i 1 W (nr. fM-4) ND * * * * (discharge)

V (nr. Aaooo) 350. ND H> It/ ND M) M)

ND - Not Patftc

Indlcataa dteaical present In sample

C' C ' CD TABLE 6

l^kll »11 N>w Amy Crjuk *vl PohJ Mtt ir Qwllty jilt r«l Inn* liaj/11 • -I) IkHMtkir 1*41

SLttl.nl I II III Station IV SUI !«"**•». (M. CijteiU

4. CMI 4.4M 4. Mil 0.144 O 40ll <4.4I4 <0.4I4 <4.4I4 <4.4I4

CJ.,11 ' <4.0IO 4.414 •.420 <0.4IO 0 040 O.U22 <4.424 C4.424 <4.4M <0.424 4.204 l.000b ll>M 1.744 2.144 4.4M 147.OM <4.444 <4.444 <4.444 <4.444 <4.040 O.l,'1 <4 024 <4.«N <4.424 <4.424 <4.4t4

4 2*1 4.«N 4.414 4.IM 4.470 Itnc 4 444 4 444) 4.424 4.424 4.144 0.»2J 4.0M 4.4M (4.414 4.4)4 <4.4IO VM»||I« <•.•!• <4.4I4 <4.414 <4.4I4 <4.4IO Criclua I).4M 12.IM II.4M

7.700 1.744 7.W4 7.M4 4 «0 17.*M 24 MO M.m 24 7M 11.40 <4.4I4 <4.4I4 <4.M4 <4.4t4 <0.4IO <4.4»4 <4.424 <4.424 <4.424 <4 020 <4.M« <4.4»4 <4.4I4 <4.4I4 0.74C

<4.4IO <0.4I4 <4.4I4 <4.4I4 <0.0«0 0.04 Hirotry <4.MI <4.MI <4.MI <4.MI <4.UII 0.0000011*1 Tta <4.424 <4.424 <4.*M <4.424 <4.020 •llnxr <4 424 <4.424 <4.4»4 <4.424 <4.IU4 O.OU4I

C- j -CrlttrU tor Llf« - loUl C nl IM. IM/L-M Ctfa. fdftl b • CrllirU tor r*n4*»»Cir o c - *>•«» UMlclty Crlt«rU tor V/M(lc Lll« 10*1 en 1.1*1 1 (0*1 c TABLE ?

Army Creek Landfill New Caatle, Delaware Army Creek Hater Quality

Baae/Neutral Organic Compounds (ug/lt)

Bis(2-ethylhexyl) Di-n-butyl Location • Date Phthalate Phthalate

Upatraaai Sept. 1983 13.2 83.6

Downstream Sept. 1983 NF 40.1 Surface Water or 3.0** 3.0a* Criteria

* Analysed by New Castle County Laboratory

NP - Mot Pound

a * Criteria for Freahwater Aquatic Life for Phthalate Baters (CWA) • - Apparent Threahold Limit Values (CMA)

c C~' CJ TABLE 8

Cr«mk Ma* CMtlt), Any CrtMtk M*tnr Quality

Tut*I Inorganic OOMCMIC ration* l«j/l I - IS II *I '1• I i !t: i I§ i iI

. IMI

C1 OMUL.!* Stfjt. IM) »i->7 l.t.0t ° 0./.. ,b J U.UU4I c U (14 l.« u O'-. . C1':

M.W C«

JIL 11«\nliuM 1 1*1 1 V-l.iii CMA) '• UifiMII UH i^ulubly lc_Kjiul trtM OLMIIJIIK:! Liy UUIIKJ IM) in |«jl yn»:lliuiu.- omi .iln.i

• • Wdior Quillty Critorlu tor UIMUH lk.il ill - r'lali a.i.1 1)1 llifcurj MVMci |(.VMI b - C(ltu(i« (or frtr«l**il«!r AqiulIC Lite IOMI fur TABLE 9

Any Cm* Undfill Maw Cantla, lM*mt» Any CMnk and rend fladiwmt Quality total Inoriytnlc GcMaantratlona MUC Sailing and Anatyaia

CfjMXjntrattoa Station 1 Station 2 Sutlon J Station 4 SUtion 5 Station i Station 7 Station 4

IMMI 21.9U2.000. 9.505.000 44.410,004. 10,5)0. 0*0. 45.175.000. 27.942,000. 2,047.000. 14,259,000. MH»jana«j 147.000. 190.000. 274, OM. m.ajs. 045.000. 1. 120. 000. 24.240. •7.020. ClrCMllM 10.490. 10.210. 25,540. 70. Silver

u~l 21.400. 142.000. 175,000. 25.410. 70. 410. 54",750. 10,110. 11,490. C*ha)iM * <10.000. '1> c c> aarluai 42.4UO. 10,110. 214.000. 79.720. 145.000. 74,440. clO.OOO. W.J40. en o . Q-- SUtlon 1 Ana/ Crook, Mkc«t of Noutd 1) Station 2 Ana/ Cruok. Ba.it of fkniUi 11, U|Jut(od« of Heir SUtloii 1 Ana/ Cr*uk. PutJ bttrwun Station 4 Ar^ Cr«jk, PakI Kffluunt SUtlon 5 Aray Croi*. IHkLir iuJIrodd Brlvt^u SUtlon 4 Aray Crook. TlJal G»tJ, Ba.it of ftuuL.i J SUtlon 7 GTJWJ) f>lt Pokl SUtlon • InUtrialtttfiit Slr«ji« Ca.it of IXi 4 <;

Itwlclty j/ur»li4lblo ouikxiiitcatloii ui Uiwt iimli>/lc Precipitation Diagrammatic water budget

Vegetative cover

Drain layer. Percolation through soil

Pfjrcotetton through

Percoiation through

Percolation through existing

MULTILAYOI CAP SYSTtM PflOFILf

naum • A rt u u u b o / Vegetated Layer

Horizontal Drain Layer Multilayer Low Permeability Soil Cap Barrier Layer System Regraded Surface To Treatment/ Discharge

7 Upgradienl Existing Soil FIN Inierceptor Cover Surface (Local Granular SoUe)

C> C,' CM O* C.

N-S CROSS SECTION: ALTERNATIVE 4 A Well Point System Final Cover/Cap System to Dewiater the Saturated Raiuae Before Reburial WMI Be Required- Discharge to Treatment 1 Reburial ol Removed Refuse V A Rekiaetobe Removed; Area to be BackHNed wUh Existing Refuse Clean Soil FIN

C> C Ci en o > i WE CROSS SECTION: ALTERNATIVE 5 TABLE 10

C ' REMEDIAL METHOD COST ESTIMATES - Amy Creek Landfill o en Method Total Capital Total Monitoring/Maintenance Cost Total Present Coat Annual Present Worth (I) Cost

1. No set ion - Monitoring $250.000 $113,000 $1.065.000 $1.315,000

2. Downgradient puaping $120.000 $272.000 $2,565.000 $2.685,000 1. Downgradient pimping and landfill capping $(2.030.000 $307,000 $2,895,000 $14,925,000

4. Downgrsdient pimping Non-phased $12.340.000 $393.000 $3,705,000 $16,045.000 landfill capping and Phased $12.030,0007 upgradiant pimping $310.000(2) $306.000/$87.000O) $3.140.000 $15,290,000 i. Partial reaoval and on-slts disposal, $35.500,000 $296.000<4> $2,430,000 $17,930,000 capping and downgradient ptmping

. On-alte incineration $113,500.000 $272.000 $2,565,000 $108,250,000(5) and doungradient pimping

. Off-alce disposal at an approved landfill and downgradient pimping $239,900.000 $272.000 2,565,000 $243,000,000

(I) Assimes present worth valnea based on a discount rate of 10Z over 30 years.

!2) Asaimes construction of upgradient pimping In 10 years £$310,000.

3) Assimes operation of upgradient pumping in 10 years £$87.000/yr.

4) Anticipated annual cost for 15 years after which annual cost Is reduced to $96,000.

5) This coat estisiate ia a result of subtracting the revenue figures fro* the total coat of tlie project. TABLE 11

tVMHATIlM Of HM4U1IM- M f HO AUtWMTIVGS

a»,-r TtUMICM. OMU944B MMJUIMi- rw HNHJC IKM.1M AND OOMMITV MONTM UM*MTS

I. tkr-fcA I>M Without hydruloalc ountrola, nut AIL*In o IkMltataa. O»ty tha onataBlaata pliaw Mill DOB* not folio, |>U>ltc atorata fucthar 9ild»ll«M of lha O>* raaultlaf la potaatlal Ground t*t«r Ptut«ctlun fa by lagaatloa of or- •Uatagy. ICKMOll atltuaata abowa UM MMlth alak Criteria.

lha oantlnuad production of laadMta, Mould aot ba ooaj~* Uollad continuing lapact OK Ooluat4a ajvl rwoMac

J. OuMauradlMMlty of laadMta ajaaaratad r** periodic fro* praclpltatloa rahabllltatloM avd MMar tafllUatloa UM landfill will aot ba ra-

Mill ODHtlMM

I. r*»a*jradta*t 14.Mi Public ajMltb rlak raduoad by Moradlng and backfilling UM dladMroa of recuv- Hil* •IteiiMllve 41 o Mmltoclau oantalalitg UM oontaalaant of UM aalatlag oanac la aradAtaatad ground ualar Lain* ajjirilcable and o Stack*! -t» to pluaa by'awMM of a bydrologlc raoulrvd to aitabllali • pwfunMl within • lA»*nt public prUta fr«ata«at dlvlda. alta ooatour pittara to ty p and an^iianauntal proaota nai-off ••y from •jiprawal ptoca**. atamairiti. lawMIII 0«pla« lafilttatloa of praclpitatloa laadflll. Iburadlag to pamlt r«aulr«d If trxt- o Slta aagraAlaa ant Uwouoh UM landfill will ba flattaa out aalatlag •d dlacfcar^a U to May Surf«oa Nata Olwar radocad ovar Mt by ocuplng •lojMa to aiaura alopa Ctaak. c> aloaa UM landfill, aufcu-lng laa- atablllty aay ba r»|Ulrad. C>

01 TABLE 11

louitlnutftl

OUif Ifl.4tt4l TaUMUAt. UMJttaaj rVJIiSjIr HMM.IC IKAI/IM AMI lr4MrVMtnNCK-aB.IAall.ITV ' WMtt OM4MITV •gnu *wii«344»ir>4. o>m»B IMHjiafrrasiu-K-Snftfff t auroOT ONCBMNS uM4um> 1. louutlauiall ,

a CM Matting ground watar claaaalau but at Sid* alopaa In UM floud Iter* ara arm deaiun an unknown rata. Infiltration plain auat ba protact*! *t*Ad*rda for-am (ace Into landfill of ground watar with rip rap oowar. npplag. friai QolUBbla auitlfar along will aa northMaatara alda will onn- tlnua. Oaitaalnation of both fubllc Ooluafcia aad PrtiMM auulfar activity at UM landfill onutlaua. aita au*t b* ad^roaatf.

All atata aroalon, aadl- aaat, aad duat control ojdlmncaa would *H>ly Airing oonatruction and until a wagatatad oowar la Mtabllakad.

4. tin J lilt nfV"^* 14,»4 ruullc hMlth rlak raduoad by gaaa a* |) ft In additloai «an* a* I) ft In addition. Undar UM (Jiaaa) ap ounUlalna UM ooataalaant «M affldaNcy of UM w>- will Inatallatlon paralta pjonch UM effact ui I pluaa by «MMM of a hydrologic gradlaat puapiaa wall for UM aaw vigradlant UM ground >•!« ftaaqraillanf tUBpIng dlvld* oraata by daoyailaat ackaaa la laraaly dapav- w*lla ka«a to ba obtalnad quality a* a reault o MoMltorlaf puopjag. dant a* UM aanunt of ra- froa UM Stata of of capping the Uikl a OiaolMraa to *p- ' Onaroa Uwough UM land- DalawMa. fill will b* aunitoi^i prorlata ttaat- Infiltration of praclpltatloa fill axd UM watar laval and aaaoaaad i«lor u> aaat Uirouak landfill raducad at* alavatlOM to IWJMM Craak. Initiating M% by oapplaa UM Undflll. fuapl<4 tandf III C*vp4ng VMaaat oowar provldaa oaly Aa with UM dawngradlant q ill i rajailllnj i 121 raductloa ia laf lltratloa. ayataa, UM umradlaM will Ihla altarnat Ive Surfaoa Matac raojulra parlodic rahabtl- attain* Mwaralon* Ikigradlant (uaplng natwork Itatloa llaltlallyl awl ralavant public health - ' proprlata Tnxt- Altar Initiating uugradlant 1 '• ' aaut I*>«I>Ili«g will h**tm ground ottfi cl«M«alng long-tan* •ffm.-t .* l*»a |unplng of djwngradlent i

* t\a)ilng taxal for avaluatlun TABLE 11

louitlnmll

a*ff 1*1.t TeUMICAL UMJUMB MSrl lUrlnMAI. NBJIIIItt- MSeMI HNH.IC I4IM.1M AMD IKNTOMnMCK-aB.IAail.ITi ' NBffB OOMN| ry ALTDMATIVt •arm U4U OMJBIMS CUMOrTS

4. It, 444 Sen* a* I4a a* I4a Saw a* 14 Under Uw luii aivroadi all ia*«lial action will be Initi- ated alaultanouuuly .

S. Partial thavwal and Public Health alak reduced by la waatara part Saaa at II In adJItlon, Ihl* *lteinatIve Mapoaal Oi-Slta ooutalalag mntaalaant plua*. faalow UM MUar Ubla odor would b* a *lgnl- ettalna afifillcable o ajoradlaj. aack- will hava to b* dawatarad flcant ooncarn to UM and relevant ruMIc fllllng. Surface by upgradlant puaolng. looal public. l«:ra*» hualth and aivliun Mater Mvaraloaa •aoowarad watar will nolaa la alao a ooncarn aantal atanodrd*. Infiltration by eliminating raqulra ti« dWIng aicavatlon and tawMIII Cawing UM •vMfOai of •• dlapoaal operation*. o OB* Wanting aratlon aad kaa additional rraa liquid drainage and banaf It of aot ran* lag ad- duat can ba oontrolled DuMkjradlant ditional MBtar froa lootl ualng atanderd con*t ruc- o Monitor lag at to Mtaraattva 4. tion approaohaa but odor o Macharga to »pj»vj will ba aora difficult. prlata tr« Opplng of aaatara eactlon after raaoval aad dlapoaal of A potential alopa ateblllty wMtara aactloa will algnlfl- problna aay reaalt along oaatly reduoad precipitation UM aapnaai cut aactlon ba- Infiltration. Source raaowel awl otpplae of landfill will era aactlon aa aBcavetloa beaten a ground watar claana- raault* to daa» out* Into Ing raduclng lowj-tara punplng. rafuaa.

During aaoawatlon duat ft odor SjaclalAaa»rdaua waataa an- problaaa will occur aa wall aountared will rauulra a* UM draining of fraa watar apaclal handling awl tran- friM aaturatad rafuae.

4. O»-4lta laolaaratlua 104,004 public health and anvlr- •ultablllty of Potanac Ooapllance with OelaM*ie Itila •lleiiullve Mia o QtB|4lag tlon control davlcaa rauulrad orddr of •M^nlliktu c> under ICM will reduce the re- MM rafuaa froa off-alt* Oi-Slta Incineration re- greatvr Utan Altai CD Dna»:h en o Monitoring the air. alta and aiaad with the a*urooua Na*te Mature- uffer eliallar public o Maonarua) to Hi*0' aaturatad waate to aaka •ml paclllty Puiait I* health and envlim- prlata Traat^aat Incinerator aah and residue It burnable. required. •untal benefit*. backfilled on elle In areae *hrnr« ground witer table. antlcliJelaJ. TABLE 11

taunt I mull

UafT 1*1.4441 Man flrrily - with UM evcavatioa of Uadflll will require Clean Air nut rafuaa. ICAAI panalte.

envlronennral and kvalth ooHoaraa are Utb Uaaaport of raw rafuaa to UM Anay Creak Site Including nolaa.

1. Off-Slta Dtauoaal by 241.1 9aa« public heal tb and a*wlr- Mail lability of Tranaportatlon of htaard- a* It. tawafllliaa ON aAwomu onaantal baaaflta a* Altar- anprouad alta* . oua uaate to an off-alla Ska) natlvaa 4, 9. aad C. fkait, dtapoaal facility require* « Ooaylata aamnwl of odor, drainage of fraa water •CM «BV parnita. Undflll froa UM aaturatad rafuaa. rln of Sat- awl aolae problaaa will arlae Public awaaltlan to UiU froa UM a»r»i>atloa aad haul- •Iternatlve reeulted In tog qparatlon*. UM cancellation of an earlier plea for a dla- naaajradlant poaal elte adwceiit to o Naaltorlajj Amy craak alta. o> Oiaonarja to Appro- priate Trmtaaal

X" •30 C' c:

C/i RESPONSIVENESS SUMMARY

ARMY CREEK LANDFILL SITE NEW CASTLE COUNTY, DELAWARE

SEPTEMBER 1986

This comnunity relations responsiveness simmary is divider! into the following sections:

Section I: Overview - A discussion of the EPA's preferred remedial action alternative. Section II: Background of Coanunity Involvement and Concerns - A brief history of the conmunity's interest in and in- volvement with the Army Creek Landfill Site, including a discussion of concerns raised by conmunity members and officials during remedial planning activities. Section III: Stannary of Public Corrtnsnts Received During the Public Comment Period and Agency Responses - A summary of comments categorized by topic and followed by EPA responses. Section IV: Remaining Concerns - A description of remaining camtinity concerns that should be considered as the EPA and the State of Delaware Department of Natural Resources and Environmental Control (DNREC) conduct the remedial design and remedial action at the Array Creek site.

In addition to section* I through IV, a list of EPA community relations activities conducted at the Array Creek site is included as Attachment A of this reason* ivenesa summary.

A R U u U o / D - 2 -

I. Overview The Remedial Investigation (RI) Report and the Feasibility Study (F3) Report «ere released to the public for review and comment on August 21, 1986. This marked the opening of the comment period, which extended until September 22, 1986. During the comment period, the EPA recJinnended a preferred remedial alternative from among the seven alternatives presented in the FS report. After careful review of and consideration of all alternatives developed in the FS, the EPA and DNREC recommended the phased approach described in Alternative 4. This alternative includes the following components: 9 Regrade the landfill surface to assure a finished compacted surface and install a capping system to minimize infiltration of rainwater. 0 Continue the operation of the downgradient recovery well network. 9 Evaluate the capping system and the downgradient pumping network for five years after the cap is installed to assess systann effectiveness during operation. This evaluation would include, but not be limited to, monitoring water levels, pumping rates and water quality. 9 After the evaluation period, if conditions necessitate, install upgradient controls to intercept lateral groundwater inflow on the northwestern boundary of the landfill. 9 Continue monitoring of water levels, pumping rates and water quality.

II. Background of Community Involvement and Concerns The Army Creek Landfill Site is located 2 miles southwest of New Castle, Delaware, the site is located on the northwest bank of Army Creek, which discharges into the Delaware River within 1 mile of the site. A. residential development of more than 200 homes, Llangollen Estates is the nearest and most directly affected cosBunity. Just beyond this residential area lies the Artesian Water Ccavpany's well field, which supplies water to approxiinstely 5,000 people. The site was originally used as a sand and gravel pit. The New Castle County purchased the property in I960 for use as a municipal landfill. Waste was deposited from 6 to 35 feet deep ever an area covering 44 acres.

A R u u u D y 6 - 3 -

The residents of Llangollen Estates expressed their concern over the landfill as early as 1960, when plans for the municipal landfill were announced. The Llangollen Estates Civic Association filed an un- successful legal action to prevent the landfill from opening. Throughout the active life of the landfill, residents of Llangollen Estates complained of rodent and odor problems. The number of complaints decreased substantially after the landfill was closed and covered with sand and soil. In 1971, one Llangollen Estates resident complained that the water in her home had an odor and stained her porcelain fixtures. The water was analyzed and found to be contaminated, as was water from several other private wells. Presenrly, most Llangollen Estates residents are receiving municipal water supplied by the Artesian Mater Company. Residents of Llangollen Estates have followed closely the activities of all government agencies involved with the Army Creek Landfill. However, communication between government agencies and citizens during the time between signing of the FS Consent Order with New Castle County and release of the FS document was limited. This lack of communication was a major concern voiced by citizens during the comment period.

III. Summary of Public Comments Received During the Public Comment Period and Agency Responses Technical Questions/Concerns Regarding Remedial Alternatives 1. A resident asked for an explanation of upgradient controls. EPA Response - The installation of upgradient controls is an option to be considered after the five-year evaluation period. The capping system and the downgradient pumping network will be evaluated for five years after the cap is installed to assess the system's effectiveness. If necessary, upgradient controls such as recovery wells upgradient of the landfill or trenching around the landfill would be installed to prevent lateral flow through the fill material. 2. One ccsM*»ntor asked what was being done at present to control the contamination into Army Creek. EPA Response - Contaminated groundwater pumped from the recovery well system at the Army Creek Landfill is discharged into Army Creek. Presently, DNRBC is drafting an NPCBS permit which will establish safe and appropriate levels for contaminants now being discharged into Army Creek. 3. One ccansntor questioned if the quality of the recovery well water would improve upon completion of the remedial action and if so, would it be plausible to punp this water into the Wilmington Mists Vtoter Treadnent Plant instead of into Army Creek.

A K u U U D / / - 4 -

EPA Response - Once the landfill is capped, the quality of ground water should improve. Pumping into the Wilmington bfeste fcfeter Treatment Plant is an option that will be addressed at a later date. 4. A resident asked how much water was presently being pumped into Army Creek. EPA Response - Approximately two million gallons per day. 5. Another resident asked how close the contaminants are to the well field. EPA Response - The contaminant plume extends to approximately 1500 feet away from the Artesian well field. 6. Several commentors questioned the timetable for the remedial action. EPA Response - Negotiations with responsible parties generally are limited to 90 days. It is anticipated that the Record of Decision (ROD) will be finalized by September 30, 1986. Tne actual design phase of the project could take up to one year to complete. After the design phase, the remedial action will be implemented. Once the action is completed and the cap is in place, the site will be monitored for five years to determine if the levels of contamination decrease. An evaluation will then be made regarding the need for upgradient controls. 7. One resident questioned what factors the Feasibility Study (FS) took into consideration. EPA Response - The Feasibility Study considers not only what contaminants are in the landfill, but the pathways by which exposure can occur to both humans and the environment. The purpose of the FS is to evaluate various alternatives to remediate the source and the contaminated groundwater. Public Health/Environmental Concerns 1. A resident asked if anyone could say with reasonable assurance that there will not be a lateral flow of contamination into the landfill. EPA Response - EPA will evaluate the effects of any lateral flow upon completion of the cap. If the effects are significant, upgradient controls will be installed. Public Participation Process 1. Several residents expressed their concern over the lack of information and opportunities for public participation at the Army Creek site.

A R u o U 5 / CJ - 5 -

EPA Response - EPA representatives offered to make themselves available for small group meetings to discuss the FS in detail. EPA also stated that there will be many more opportunities in the future for residents to be involved with the decisions made at the site. 2. Several ccmmentors requested additional time to review the FS and the preferred alternative. Several residents said they were outraged at being given only 21 days to comment on a study that took 2 years to prepare. EPA Response - A decision to extend the public comment period could not be made at the meeting, but would be taken into consid- eration with the other comments received, both written and oral. (The comment period subsequently was extended from September 15 to September 22 as a result of this request.) EPA explained that citizens would have input for the duration of the project, and that this Record of Decision could not address recovery well discharge. 3. Some residents indicated that EPA should begin the cleanup as soon as possible, and that additional delays should be avoided. EPA Response - None. 4. A representative of the Llangollen Civic Association asked if EPA would meet with knowledgeable comrauni ty members once they had a chance to review the FS. EPA Response - Agreed. Cost/Funding Issues 1. A ccmmentor questioned what the cost of the remedial action would be. EPA Response - The present worth cost of the remedial alternative over the next 30 years approximately is $15 million, this includes capital costs. 2. One resident asked how much New Castle County had spent to date on the Arjay Creek Landfill. EPA Response - New Castle County has spent $3.85 million to date on the Feasibility Study and the installation, operation, and maintenance of the recovery wells. 3. The Artesian fertsr Company claim that its pumping capacity has been reduced due to groundwater contamination. The company believes it should be compensated for this loss as part of this CERCLA action.

Aft U C G 5 / - 6 -

EPA Response - This question has been discussed at length by EPA, the Artesian Water Company ("Artesian") and New Castle County before and during generation of the Feasibility Study. It is Artesian's position that it has been forced to draw Less water from its wellfield because of the contamination leaching from Amy Creek and operation of the recovery 'well system. Artesian regards the reduction in capacity as a response cost under CERCLA. New Castle County is of the view that, if Artesian has lost any capacity from the wellfield, it is for reasons other than pollution fron the landfill. The County has argued that Artesian has never been entitled to draw more water than it presently takes from the wellfield, by virtue of state authorization and salt water intrusion. Artesian has sued New Castle County, and some other parties over this question, and no final resolution of that- case has been reached. Both Artesian and the County vigorously presented their respective positions to EPA during preparation of the Feasibility Study. The regional staff consulted with headquarters about this issue, and the final result was a memorandum from Gene A. Lucero, Director, Office of Waste Programs Enforcement, to Steve Wassersug, Director, Hazardous Waste Management Division, Region III. In short, the position of EPA is that replacement of aquifer capacity is not a goal for this CERCLA cleanup. The wellfield currently in use is being protected by the existing recovery well system, and other remedial measures recommended for this site should prevent future contanination of the aquifer related to contamination from the landfill.

&' Attachment A

Community Relations Activities Conducted at the Army Creek Landfill Superfund Site.

9 August 3, 1984 - EPA announced signing of a Consent Order with New Castle County to perform a Feasibility Study for the Army Creek Landfill. 9 November, 1984 - EPA completed a community relations plan. • August 18-20, 1986 - EPA contacted local officials and citizens regarding release of the FS and set up information centers in the community. 0 August 21, 1986 - The FS was sent to 4 information centers, and a press release announcing completion of the PS was distributed. • September 10, 1986 - A public meeting was held to discuss the findings and recommendations of the FS. 9 September 15, 1986 - The comment period was extended until September 22, 1986. 153 H to

AROG0582 RECORD OF DBCZSZOaf ABUT CBBBX LAMDVZLL OPBRABLI UVZT §2 DECLARATIOM

Site ffame and Loes.fci.oii Any creek Landfill Sits Operable Unit 12 New Castle, Delaware statement of Basis a,pfl purpose This decision document presents the selected remedial action for the Army Creek Landfill sits in New Castle, Delaware, which was chosen in accordance with the requirements of the. Comprehen- sive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) , as amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA) , and, to the extent practicable;, the National oil and Hazardous Substances Pollution Contingency Plan (NCP) . This decision document explains the factual and legal basis for selecting the remedy for this site.. The, Delaware Department of Natural Resources and Environmental Control has not concurred with the selected remedy. The, information supporting thie remedial action decision is contained in thai administrative record for thie site. Assessment of the Site Actual or threatened releases of hazardous substances from this site, if not addressed by implementing the response action selected in thie Record of Decision*.- (ROD) , may present an imminent and substantial endangerment to public health, welfare, or the environment. Desc Thie operable unit ie the second of two operable unite for the site. The Record of Decision for the first operable unit selected a remedial alternative for source control including the installation of a 'multi-layered landfill cap and the operation of a recovery veil network downgradient from the site to prevent contaminated groundwater from migrating to potable water supply wells. Thie second operable unit addressee the need to treat the recovery well dischargee prior to discharging to Army Creek/ Pond. The selected remedy will reduce the concentration of iron in the extracted groundwater to a level that is protective of the designated ueee of Army Creek. A monitoring plan will be implemented -to ensure continued compliance with all applicable standards. Together, the implementation of the overall remedial action strategy selected in the first operable unit ROD and the second operable unit ROD will provide a quality of water in Army Creek/Pond that ie protective of human health and the environment. Hazardous substances will remain on site, therefore long-term management will be required. The primary component of the selected remedy is the con- struction and operation of a water treatment facility that is capable of reducing the concentration of iron in groundwater recovered by the recovery well network prior to surface discharge, amounting to about 1.4 million gallons/day. This remedial action will require long-term management to assure compliance. Declaration of Statutory Determinations The selected remedy ie protective of human health and the environment, compliee with Federal and State requirements that are legally applicable or relevant and appropriate to the remedial action, and ie cost-effective. Thie remedy utilizee permanent solutions and alternative treatment (or reeource recovery) technologies to the maximum extent practicable, and it satiefiee the statutory preference for remediee that employ treatments that reduce toxicity, mobility, or volume ae their principal element. Because thie remedy, will reeult in hazardous substances remaining on eite above health-based levels, a review will be conducted within five yeare after commencement of remedial action to eneure that the remedy continuee to provide adequate protec- tion of human health and the environment.

Erickson Date ional Administrator Region ZZZ

AROG0581* RECORD OV DECISION REMEDIAL ALTERNATIVE SELECTION

ARMY CREEK LANDFZLL 8ZTE OPERABLE UNIT *2 NEW CASTLE, DELAWARE

AROG0585 DECISION SUMMARY

Z. SITE LOCATION AND DESCRIPTIOM The Army Creek Landfill is located approximately two miles southwest of the city of New Castle, Delaware (Figure 1). The landfill is bordered to the north and west by Conrail tracks and on the south and east by Army Creek. The highways adjacent to the Landfill are Routes 13 and 40 to the west and Route 9 to the east (Figure 2). Llangollen Estatee, a residential development, is located 1/4 mile southwest of the site. Delaware Sand and Gravel, another landfill which has been placed on the Superfund National Priorities List, is adjacent to Army Creek Landfill and separated from it only by Army Creek, a tributary of the Delaware River. The Army Creek Landfill, a former sand and gravel quarry, is owned by New Castle County. The County operated this approximately 44-acre landfill which accepted municipal and industrial wastes from 1960 until its closure in 1968. During that time, an estimated 1.9 million cubic yards of refuse were landfilled at the site, 30 percent of which (or approximately 600,000 cubic yards) now lies below the seasonal high water table. In late 1971, water in a residential well southwest of the landfill developed quality problems, such as a distinctly dis- agreeable odor and permanent staining of porcelain fixtures. New Castle County began a multi-year field investigation to assess the problem. Results from that investigation showed that leachate originating from the Army Creek and Delaware Sand and Gravel Landfills was contaminating local aquifers. The County's remedial investigation led to the installation of a groundwater recovery system designed to maintain a groundwater divide between the landfills and the Artesian Water Company Wellfield located downgradient of the landfills. Contaminated groundwater pumped from the recovery well system is currently discharged to Army Creek. Army Pond, oriented parallel to the southern site boundary, is ellipsoid in shape and approximately 2,000 feet long, 175 feet wide, and 1 foot deep. Storm water runoff from the site, as well as flows from the recovery wells, are collected in thie pond. Upstream of the pond, Army Creek is a low- volume seasonal stream largely dependent on storm runoff which empties into the pond. Downstream of the pond the Creek is enlarged by the flow from the recovery wells, which averages 1.4 million gallons per day. Although the recovery well discharges represent up to 90 percent of the volume of Army creek, historical aerial photos:document that Army Creek/Pond was nearly the same size in the late 1950s. There are high quality wetlande associated with the Army Creek which are utilized by migratory birds.

AR000586 ARMY CRgJK LANDBLL SITE LOCATION Illllltlll SCAtl'T. 44400 "•HR000587 00 CO in FIGURE 9 CD Ar.TlVg RECOVERY WEtlS CD CD

HtCOVMT WfLLWBJ)

GANNETT FLEMING, INC. t. MAKTLANO Army Creek and its vicinity supports a diverse flora and fauna. Five species of special concern have been found in Army Creek or within the vicinity of the site. These are the bur- marigold, smallmouth bass, striped bass, white crappies and yellow bullheads. The bur-marigold is not found on the Army Creek Site, but rather at the mouth of Army Creek along the Delaware River. Because of the distance involved, it is not likely this species would be impacted by the Army Creek Site or its remediation. The four fish species listed above could potentially be impacted by the Army Creek site. Although these species have been found in Army Creek, they do not appear to be common species in the Creek. White crappies and smallmouth bass were found two times out of six sampling events between 1975 and 1983, while yellow bullhead and striped bass were found only once. Site Geology The Army Creek Landfill is located within the Atlantic Coastal Plain physiographic province. The coastal plain is composed of a wedge-shaped body consisting of gravels, sands, silts and clays. The site is underlain by two water-bearing formations, the Columbia and the Potomac. The Columbia, the upper-most aquifer beneath the landfill, is of Pleistocene Age and is from 10 to 60 feet thick at the site. This formation, which dips to the south- east, consists of medium to coarse grained sands, gravels, silts and clays which were deposited in shallow lens-shaped channels. The silt and clay units of the Columbia are discontinuous and do not form confining units. The Potomac Formation of Cretaceous Age underlies the Columbia Formation and is generally separated from it by a confining clay layer at the site. The Potomac Formation dips to the southeast, is up to 600 feet thick and consists of silts and clays interbedded with sands and some gravel. The formation is divided into upper and lower units which are separated by a thick confining clay unit. The upper Potomac Formation silts and clays are discontinuous and nonuniform; in some places, the sands of the Columbia and Potomac are in contact. Site Hydrogeology Hydrologically, the Potomac upper clay functions as a confin- ing zone for the underlying aquifer which is known as the upper Potomac Hydrologic zone. The direction of flow in the Potomac aquifer hae been altered significantly over the past several decades due to withdrawal of water for industrial and domestic uses. The elevation of the potentiometric surface in the 1950s, before significant development of the aquifer, was about 19 feet below sea level and flow direction was toward Delaware Bay to the southeast. In the 1960s, after wellfields were developed in the Potomac Formation for public water supplies and industrial use, the direction of flow remained to the south and east.

AROG0589 The surface of the landfill is pocketed with depressions resulting from the differential subsidence of the refuse. These depressions, coupled with the remaining flat surface of the landfill, retards stormwater from running off the landfill. The cover is generally silty, sandy and quite permeable. However, deposits of clay have accreted in the depressions so that storm- water forms ponds in the depressions. These ponds contribute to the slow infiltration of water into the landfill. Because of these current surface conditions, it is estimated that at least 50 percent of the precipitation which falls directly onto the landfill surface infiltrates through the landfill cover and percolates through the refuse. ZZ. SITE HISTORY AMD ENFORCEMENT ACTIVITIES The Army Creek Landfill occupies an area that was formerly utilized as a sand and gravel pit. The gravel pit in which Army Creek Landfill was constructed was excavated until a hard zone was encountered. This zone marks the base of the Columbia Formation and the top of the underlying clay. In 1960, the landfill began operation as a municipal refuse landfill. The landfill was operated by New Castle County continu- ously until 1968 when it was filled to capacity. Refuse place- ment, compaction and covering operatione at the Army Creek Landfill were carried out by the operators of the gravel pit under contract to New Castle County. Refuse burial began at the eastern end of the pit and generally continued toward the pit entrance on the west. The cover material used was obtained from the pit and includee residential sands, tailing pilee and siltation basin deposits. As the operation progressed, cover material and land- fill space became depleted. This encouraged deeper excavation which may have removed much of the clay layer which separated the Columbia from the Potomac formations. This in turn could have created direct access routes for leachate from the Columbia to the Potomac. Direct access routes may also have occurred naturally due to the noncontinuous geometry of the Potomac clay. In late 1971, water in a residential well downgradient of the Army Creek Landfill Site developed severe quality problems. In June 1972, New Castle County commenced a groundwater monitoring program which began with a well installation and sampling program. Monitoring by various agencies including EPA, New Castle County and the Delaware Department of Natural Resources and Environmental Control (DNREC) hae continued up to the present. Monitoring has resulted in the identification of groundwater contaminants indicative of hazardous waste disposal as well as typical municipal refuse. It was also determined that the plume of these contaminants was moving toward the receptors located downgradient of the landfill. After considering alternative water supplies for the affected residents, New Castle County paid for an extension of Artesian's Water supply lines to the first contaminated residence and other homes along Grantham Lane. There was also a settlement with the homeowners to offset the monthly services costs.

AROG059G In 1973, recovery wells were installed in the upper Potomac Aquifer by New Castle County. The purpose of the recovery wells was to intercept and contain the contaminant plume. The pumping of these wells created a groundwater divide between the Army Creek Landfill and the Artesian Water Company's Llangollen Wellfield. A modified recovery system was installed in 1980, which included placement of new recovery wells closer to the landfill in order to pump more concentrated groundwater and therefore less clean water. The present recovery well system utilizes Wells 27, 28, 29, 31, RW-1, RW-9, RW-10, RW-11, RW-12 and RW-13 (Figure 2). Based on the sampling analysis from the recovery and moni- toring wells, the Army Creek Landfill site was proposed for the National Priorities List (NPL) in October of 1981 and was finalized on the list in September of 1983 due to extensive groundwater contamination. In August 1984, EPA entered into a Consent Agreement and Order with New Castle County to perform a Feasibility Study at the site. New Castle County submitted the final draft of the study in July 1986. The Army Creek Record of Decision (ROD) for the first oper- able unit, ieeued on September 30, 1986, selected a remedial alternative for eource control but deferred selection of appropriate remedial measures for sediments in Army Pond and a treatment for the groundwater recovery well discharges to a second operable unit decision document. The first operable unit ROD eelected a two-phased approach: Phaae i 1. installation of a multi-layer landfill cap 2. continued operation of the downgradient recovery well network 3. evaluation of the remedial action for five years after the cap is installed to aseese the effectiveness of the system during operation Phase II 1. based on the five-year evaluation, a determination will be made on whether to inetall upgradient controls 2. continue evaluation of the effectiveness of the system 3. operation and maintenance The extensive studies that have been conducted at the site have identified contamination in both the groundwater and surface water. The remedial action strategy selected in the first oper- able unit, described above, addresses the groundwater contami- nation and the landfill leachate currently seeping into the surface water (Army creek/Pond). In August 1986, EPA issued Notice Letters to the identified Potentially Responsible Parties (PRPs) inviting them to design and implement the remedial action strategy selected in the first operable unit Record of Decision. The PRPs failed to achieve

AR00059 settlement with the EPA. EPA completed the remedial design of a multi-layer landfill cap in August 1989. In February 1989, EPA issued Special Notice Letters to the identified PRPe inviting them to conduct the focused Remedial Investigation and Feasibility Study with respect to the surface water (Army Creek/Pond) and sediments adjacent to the landfill. The noticed PRPs declined to perform the study. In February 1990, EPA completed the second operable unit RI/FS.

IZZ. SCOPE AMD RQT.H Qf OPgRAJM UNIT This is the second and final planned operable unit for the site. The first operable unit provided for the installation of a hydraulic barrier (cap) over the landfill to prevent vertical infiltration through the wastes and for the continued operation of the downgradient recovery well network to prevent the migration of contaminated groundwater to public supply wells. The recovery well system is currently operating and the remedial design of the landfill cap has recently been completed. Actual cap construction is planned to begin before December 1990. This second operable unit addresses the need to treat the recovery well discharges, which, as determined in the Remedial Investigation, do not present an unacceptable threat to human health but are potentially harmful to the environment. Sediment sampling revealed contaminant levels which were within a range expected to be found in a wetland environment and are therefore not an environmental concern. The contaminated medium to be addressed in the second operable unit is the surface water of Army Creek/Pond in general and the recovery well discharge in particular. IV. HIGHLIGHTS OF COMMUNITY PARTICIPATION The RZ/FS Report and the Proposed Plan for the second operable unit of the Army Creek site were released to the public for comment on March 18, 1990. These two documents were made available to the public in both the administrative record and an information repository maintained at the EPA Docket Room in Region 3 and at DNREC's New Castle office. The notice of availability for these two documents wae published in the Wilmington News Journal on March 18, 1990. A public comment period on the documents wae held from March 18, 1990, to May 2, 1990. In addition, public meetings were held on March 26 and April 21, 1990. At these meetinge, repre- sentativee from EPA and DNREC answered questions about problems at the site and the remedial alternatives under consideration. A response to the comments received during thie period is included in the Responsiveness Summary, which is part of this ROD. V. SITE CHARACTERISTICS As documented in the first operable unit ROD, the groundwater beneath and downgradient from the site is contaminated by both organic and inorganic pollutants at levels exceeding the drinking water standards. Drinking water standards are the applicable standards for groundwater because it is withdrawn and used as a potable water supply. The first operable unit ROD selected the continued operation of the existing recovery well network to prevent the horizontal migration of the contaminants to any potable water supply well head. The groundwater recovered by the recovery well network is currently being discharged to the Army Creek/Pond surface water. A determination on the level of treatment required for this recovered groundwater prior to surface discharge is the primary objective of this decision document. Drinking water standards are not appli- cable to the Army Creek/Pond surface water because the creek water ie not classified as a potable water source. EPA and DNREC have established relevant water quality standards pursuant to Sections 304(a) and 303 of the Clean Water Act, respectively, in order to protect the designated uses of Army Creek/Pond. The designated uses for Army Creek/Pond include the following: secondary contact recreation; fish, aquatic life and wildlife. The fresh water segments are also designated for agricultural water supply uses. Surface Water Two studies have compared the stream biota of Army Creek from locations above and below the landfill, beyond the pond outlet. The study conducted in 1985 by the State of Delaware found species richness at stations above and below the landfill to be similar. Both stations exhibited high densities of macroinvertebrates but relatively low species diversity. Of the species present, facultative and pollution-tolerant organisms predominated. The authors suggested these communities were indicative of moderate inorganic enrichment. The second biomonitoring study was conducted in 1986 by EPA. This study had three study sites, one upstream from the landfill, the second in the Army Creek Pond, and the third downstream of Army Creek Landfill. Results of this study were similar to those found in the 1985 State of Delaware study. The EPA study did find that the downstream benthic community had more taxa and fewer organisms per taxa as well as more groups intolerant of water pollution, indicating a slight improvement in water quality over upstream stations. The pond station exhibited very low species richness and 95 percent of the groupe found in the pond were pollution tolerant. This indicates poor water quality in the pond. In summary, Army Creek both above and below the landfill appears to be nutrient enriched. Although chronic toxic effects due to landfill effluent may be present, the effects cannot be distinguished from the stream biotic communities due to the confounding effects of the stream enrichment. The improvement in the benthic macroinvertebrate community below the pond outfall does suggest that the pond may be operating in a limited capacity as a filter or aeration system, improving the water quality of the outflow water. Based on questions raised by the State regarding the repre- sentativeness of the results cited in the Remedial Investigation and Proposed Plan (taken from a report on chemical analyses of fish samples collected in 1983) a new sampling event was conducted. In May 1990, separate bioassays were performed on composite fish fillet samples of five common carp and six american eel collected by DNREC. Results showed some inorganic contamination by zinc in both the carp (11.2 ug/g) and the eel (14.9 ug/g). No additional

ARG00593 inorganic constituente were identified. Organic analyses of the composite fish fillets have not yet been completed. The fish in the study were collected below the landfill at the edge of the Army Creek Site. In August 1988, the EPA field investigation team sampled Army Creek for priority pollutants. The data indicated the presence of organic and inorganic contaminants in the waters of Army Creek (Table 1). Organics detected included: bis(2-chloroethyl)ether, 1,2-dichloroethane, and phenol. Inorganics detected in two or more sampling locations included: cadmium, chromium, iron, mercury, and zinc. The organic contaminants were well below the Delaware Sur- face Water Quality Standards (DSWQS) which are known to be protective of the aquatic environment. The concentration of bis- (2-chloroethyl)ether may exceed the numeric DSWQS for protection of human health via fish consumption (identified concentrations are below detection limits). The concentrations of cadmium, iron, mercury and zinc were found to exceed the Delaware Surface Water Quality Standards for chronic toxicity (Table 4). The analysis for chromium did not differentiate between valences; however, the rela- tive toxicity of hexavalent chromium is greater than trivalent chromium. If the majority of the total chromium reported is in the hexavalent form, the level doee exceed the criterion. Oroundwater Recovery Well Discharge There are currently ten recovery wells pumping groundwater and discharging to Army Creek/Pond. New Castle County hae arranged to direct the water pumped from one of the ten wells (RW|9) to the Wilmington POTW. The sampling of the remaining nine recovery well discharges was carried out on July 6, 1989. The recovery wells sampled, referred to by the well number assigned to them by New Castle County upon installation, were numbered 1, 10, 11, 12, 13, 27, 28, 29, and 31 (Figure 2). To determine the combined effect of these discharges on Army Creek/Pond, the flow weighted average concentrations of the compounds found in the recovery well discharges were calculated. Although many organic (Table 2) and inorganic (Table 3) contami- nants were detected in the discharges, only iron definitively exceeds the numeric surface water quality criteria. The flow weighted average concentration of bis(2-chloroethyl)ether in the discharges may contribute to an "in stream" concentration that may exceed the numeric criterion established to protect human health from the fish consumption exposure route. The current data is insufficient to make a definitive determination. The numeric and narrative criteria documented in the Delaware Surface Water Quality Standards as amended on February 2, 1990 (Table 4) are the standards relevant to surface water bodies. Surface Water quality criteria are constituent concentrations, levels or narrative statements that represent a quality of water that supports a particular designated use. As such, they apply "in stream." In determining maximum allowable discharge concen- trations, the allowable dilution in the receiving stream is

AR000591* Table l of Analytical Results for surface Water sampling Army Creek Landfill Mew Castle, Delaware Organic contaminants No. of Range of *Average Instrument Method Positive Concen- Concentra- Detection Detec- Detec- trations tion Limit tion Chemical tions/ (ug/L) (ug/L) (ug/L) Limit No of (ug/L) Samples Bis(2-Chloroethyl) - *** ether 3/8 3.6-7.5 3.4 3.6 10.0 1 , 2-Dichloroethane 2/8 2-5 1.6 2.0 5.0 Phenol 8/8 92-213 157 50 50.0

Inorganic Contaminants No. of *Range of ** Average Instrument Method Chemical Positive Concen- Concentra- Detection Detec- Detec- trations tion Limit tion tions/ (ug/L) (ug/L) (ug/L) Limit No. of (ug/L) Samples Cadmium 5/8 34-38 25 10.0 10.0 Chromium (Total) 7/8 57-150 84 50.0 50.0 Iron 7/8 980-2,860 1,549 500 500 Mercury 2/8 0.2 0.13 0.2 0.2 Nickel 1/8 150 62 100 100 Thallium 1/8 610 295 500 500 Zinc 8/8 25-640 167 10.0 10.0 * Concentrations in lab analyses labelled as estimated, "J", were assumed to equal listed concentrations. ** Values of 1/2 of the Instrument Detection limits were used for the values of the nondetected results in calculation of averages, *** Each detection identified below the method detection limit; therefore, concentrations given are approximate values. Note: Surface water was analyzed for TAL and TCL; only positive detections reported in summary table.

10 ARGG0595 Table 2 Summery of Analytical Results for Recovery Well Discharge Army creek Landfill New Castle, Delaware

Organic contaminants

No. of •Range of •* Flow Instrument Method Positive Concen- Weighted Detection Detec- Chemical Detect- trations Average Cone. Limit tion tions (ug/L) (ug/L) (ug/L) Limit No. of (ug/L) Samples Benzene 4/9 14-18 8.0 5 5 Bis ( 2-Chloroethyl ) - 7/9 5-21 11.0 5 10 ether Bis ( 2 -ethy Ihexy 1 ) - 1/9 3 1.8 3 10 phthalate Chlorobenzene 3/9 3-18 4.0 3 5 Chloroform 1/9 6 2.. 8 5 5 1 , 4-Dichloroben- 1/9 6 3.6 6 10 zene 1 , 2-Dichloroethane 2/9 22-50 8.4 5 5 Ethylbenzene 2/9 4 2.6 4 5 Tetrachloroethene 1/9 2 1.1 2 5 Toluene 1/9 19 4.2 5 5 Trichloroethene 1/9 2 1.1 2 5 Total Xylenee 2/9 7-10 4.4 5 5

*(1) Where duplicate samples were taken, the higher concentration was used. (2) Concentration in lab analyses labelled as estimated, "J", were assumed to equal the listed concentration. ** Values of 1/2 of the Instruction Detection limits were used for the values of the nondetected results in calculation of averages. Notes Discharges were analyzed for Target Compound List (TCL); only positive detections reported on summary table.

11 ARGG0596 Table 3 Summary of Analytical Results for Recovery Well Disohargi Army Creek Landfill New Castle, Delaware Total Inorganic contaminants

No. of •Range of ••Flow Instrument Positive Concen- Weighted Detection Chemical Detections/ trations Average Limit No. of (ug/L) Cone. (ug/L) Samples (ug/L) Aluminum 1/9 132.0 29.6 12.0 Arsenic 1/9 2.7 1.0 1.8 Barium 9/9 74.5-377.0 184 1.2 Calcium 9/9 8,760-18,800 11,470 17.1 Cobalt 3/9 22.7-36.9 11.8 2.7 Iron 9/9 488-34,300 12,400 8.6 Magnesium 9/9 3,630-13,600 6,670 24.3 Manganese 9/9 249-2,710 945 1.5 Potassium 9/9 1,940-17,000 6,770 407.8 Selenium 2/9 1.4-1.5 0.8 1.4 Sodium 9/9 9,690-80,600 26,840 21.8

• Concentrations in lab analyses labelled as estimated, "J", were assumed to equal listed concentrations. ** Values of 1/2 of the Instrument detection limits were used for the values of the nondetected results in calculation of averages. Notes Dischargee were analyzed for Total Analyte List (TAL); only positive detections reported in Summary Table.

12 ARGG0597 Table 4 Chemicals Found to Exceed Delaware Surface Water Quality Standards as Amended on February 2, 1990 (DSWQS) in the Army Creek/Pond Delaware Surface Water Delaware Surface * Range of ** Average Quality Criterion Water Quality Cri- Concentra- Concentra- terion for Protec- chemical tions tion Human Health/Fish Consumption tion of Freshwater (ug/L) (ug/L) (ug/L) Aquatic life Acute Chronic Toxicity Toxicity From Recovery Well Discharge Iron 488-34,300 12,400 NA NA 1,000 Bis(2Chlo- roethy 1 ) ND-21 11 1.77 NA NA Ether

* Concentrations in lab analyses labelled as estimated, "J", were assumed to equal listed concentrations. *• Values of 1/2 of the Instrument detection limits were used for the values of the nondetected results in calculation of averages. Average concentration in Recovery well discharge is flow weighted. ND Not Detected NA Not Available o Mote: Recovery well discharges and surface water were analyzed for Total Analyte List and Target CD Compound List. Only constituents which may exceed or may contribute to an excursion of the CD DSWQS are identified. en CO

13 Table 4 (Continued)

Delaware Surface Water Delaware Surface * Range of *• Average Quality Criterion Water Quality Cri- Concentra- Concentra- terion for Protec- Chemical tions tion Human Health/Fish Consumption tion of Freshwater (ug/L) (ug/L) (ug/L) Aquatic life Acute Chronic Toxicity Toxicity From Surface Water Cadmium 34-38 25 NA 3.9 (a) 1.1 (a) Chromium 57-150 84 840,000 (trivalent) 1,737 (a) 207 (a) (Total) 4 , 200 (hexavalent) 16 (hex) 11 (hex)

Iron 980-2,860 1,549 NA NA 1,000

Mercury ND-0 . 2 0.13 7.1 2.4 0.012 Zinc 25-640 167 NA 117 (a) 106 (a) Bis(2Chlo- roethyl) ND-7 . 5 3.4 1.77 NA NA Ether * Concentrations in lab analyses labelled as estimated, "J", were assumed to equal listed concentrations. •* Values of 1/2 of the Instrument detection limits were used for the values of the nondetected CD results in calculation of averages. Average concentration in Recovery well discharge is flow CD weighted. CD (a) Hardness dependent criterion (100 mg/L used) cn ND Not Detected NA Not Available Mote: Recovery well discharges and surface water was analyzed for Total Analyte List and Target Compound List. Only constituents which may exceed or may contribute to an excursion of the DSWQS are identified.

14 considered. In the case of Army Creek, the upstream portion is considered an intermittent stream largely dependent on surface water run-off for flow. In accordance with DSWQS, the critical flows to be used in defining available dilution are: the 50th percentile or median flow; the flow of thirty-day duration with a recurrence interval of 5 years (30Q5); the flow of seven-day duration with a recurrence interval of ten years (7Q10); or the flow of one-day duration with a recurrence interval of ten years (1Q10), depending on the applicable criterion (human carcinogen, systemic toxicant, chronic toxicity or acute toxicity). Sediments In August 1988, the EPA field investigation team sampled sediments in Army Creek/Pond. The data indicated the presence of both organic and inorganic contaminants in the creek/pond sediments. Twenty organic chemicals were found in the sediment (Table 5) while only three were found in the surface water. The only organic chemical found in both surface water and sediment was phenol. Many of the chemicals found exclusively in the sediment samples have very high organic carbon partition coefficients, which indicates a propensity for soil and sediment adsorption. The metals found in the sediment samples include arsenic, chromium, copper, iron, lead, mercury, nickel, and zinc (Table 5). Phenol was not detected in the recovery well discharge sampling performed for this RI/FS, but it had been detected in earlier sampling at concentrations far below the surface water concentratione shown in Table 1. Evidently, the source of phenol is either contaminated leachate from the landfill , or contaminated runoff from off site. Regardless of the source of phenol, its concentration in the surface water doee not represent a hazard to human health or aquatic life. Levels of metals observed in Army Pond and Army Creek sediments were compared to concentrations of metals occurring naturally in U.S. soils, shown in Table 6, as compiled by Brown and Associates (1983). All metals except iron were determined to fall within the ranges cited by this source. Although Brown and Associates did not include iron in their publication, the extremely high levels of iron measured in the creek/pond sediment is clearly an artifact from the introduction of high concentrations of dissolved iron in the recovery well discharges. The Army Creek/Pond bottom's orange appearance is due to the high levels of iron which have naturally precipitated out of the water column. When comparing sediment and surface water chemical concentrations in the Army Pond versus those in Army Creek downstream of the pond the concentrations are generally of the same order of magnitude, with slightly lower valuee in the downstream locations. This illustrates the limited natural cleansing effect occurring in the creek/pond itself (volatilization/biodegradation of organics and precipitation/adsorption of inorganics).

1 First Operable Unit Remedial Investigation identified the presence of phenol contamination in some of the monitoring wells constructed through the Army Creek landfill. &R000600 VI. SUMMARY OF SITE RISKS A primary component of the second operable unit remedial investigation is the public health and environmental risk assessment. This assessment defines the potential and actual risks to human health and the environment resulting from the presence of hazardous substances in the Army Creek/Pond surface water and sediments. The potential risk preeented by the recovery well discharges alone was also evaluated. To determine whether there is an actual exposure or a potential for exposure at this site with respect to surface water, the most likely pathways of contaminant release and transport, and the human and environmental activity patterns in the area were considered. A complete exposure pathway has three components: 1. a source of chemicals that can be released into the environment 2. a route of contamination transported through soil, sediment, air or water 3. an exposure or contact point for humans or the environment (plants and animals) Potential sources of contamination are summarized as follows: 1. recovery well water discharge 2. creek and pond surface water 3. creek and pond sediments 4. air in the area Of the creek and pond 5. fish caught for human consumption Although many chemicals were detected during the sampling activities, only a few of the chemicals pose a risk to human health. The identified indicator chemicals in the Army Creek/Pond surface water included: (1)(2)<3)bis (2-chloroethyl) ether, {2>l,2-dichloroethane, "'cadmium, O)chromium, (1>mercury, (1)nickel and (1>zinc. The human health risk assessment was calculated using the maximum concentration identified in the surface water. The identified indicator chemicals in the Army Creek/Pond sediments included: (3>benzo(a)pyrene, "'arsenic, o>chromium, (1>lead, 'mercury, 'nickel and zinc. The human health risk was calculated using the maximum concentration identified in the sediments. The identified indicator chemicals in the recovery well discharges included: <1>(2)(3)benzene, <1)<2)<3)bis(2-chloroethyl)ether, (1)<2)<3)l,2-dichloroethane, (1)arsenic, <1>nickel and (1>zinc. The human health risk was calculated using the flow-weighted average concentra- tion identified assuming a single discharge point.

(1) Potential contaminant of concern with respect to inadver- tent ingestion route (2) Potential contaminant of concern with respect to the inha- lation, -route (3) Potential contaminant of concern with respect to the dermal contact route

16 AROG0601 Table S Summary of Analytical Results for Previoue Sediment Sampling Army Creek Landfill New castle, Delaware Organic Contaminants No. of * Range of •* Average Instrument Positive Concentra- Concentra- Detection Detec- tions tion Limit Chemical tions/ (mg/L) (mg/L) (mg/L) No. of Samples Acenaphthene 1/8 0.165 0.092 0.165 Acetone 8/8 0.025-0.719 0.254 0.010 Anthracene 2/8 0.180-0.339 0.132 0.180 Benzo (a) Anthracene 3/8 0.258-1.25 0.344 0.258 Benzo (a) Pyrene 4/8 0.239-1.07 0.316 0.239 Benzo (b) Fluoranthene 4/8 0.203-1.33 0.382 0.203 Benzo ( g, h, i) Perylene 3/8 0.165-0.715 0.202 0.165 Benzo (k) Fluoranthene 2/8 0.446-0.786 0.278 0.330 2-Butanone 5/8 0.004-0.029 0.009 0.004 Chrysene 4/8 0.274-1.58 0.453 0.274 Di-n-Butylphthalate 7/8 0.236-1.08 0.489 0.330 Fluoranthene 4/8 0.331-1.62 0.556 0.330 Fluorene 1/8 0.161 0.090 0.161 Indeno(l,2,3-cd) 3/8 0.182-0.808 0.229 0.182 Pyrene

4 -Methy 1 phenol 1/8 0.139 0.079 0.139 Phenanthrene 3/8 0.402-1.71 0.478 0.330 Phenol 2/8 1.20-1.80 0.693 0.848 Pyrene 4/8 0.302-3.20 0.714 0.302 Toluene 2/8 0.009-0.033 0.007 .005 Total Xylenes 1/8 21 0.005 .005

17

AR0006G2 Table 5 (Continued) inorganic contaminants No. of •Range of ••Average Instrument Detections/ Concentra- Concentra- Detection Chemical No. of tions tion Limit Samples (mg/L) (mg/L) (mg/L)

Arsenic 7/8 1.1-6 2.91 0.95 Chromium 6/8 8.3-45 19.4 5.0 Copper 6/8 11.3-43.9 21.3 5.0 Iron 8/8 1,830-68,800 22,205 50.0 Lead 7/8 6-97.8 49.6 0.49 Mercury 8/8 0.0459-0.119 0.071 0.01 Nickel 5/8 9.9-26.4 13.5 9.9 Zinc 8/8 16.4-273 106.7 10.0 • Concentrations in lab analyses labelled as estimated, "J", were assumed to equal listed concentrations. •* Valuee of 1/2 of the instrument detection limits were used for the values of the nondetected results in calculation of averages. Notes Sediments were analyzed for both the Target Analyte List and the Target Compound List; only positive detections reported in summary table.

18

ARQ00603 Table 6 Ranges aad Averages of Metals in Uncontaminated Soil Army Creek Landfill New Castle, Delaware

Range of Average Chemical Concent rat ions Concentrations Comments (mg/kg) (mg/kg) Arsenic 1-50 Usually 10 ppm or less Chromium 1-1000 100 Copper 2-100 30 Iron No information given Lead 10-200 10 Mercury 0.01-0.3 0.03 Nickel 5-500 100 Zinc 10-300 50

No information given in Brown and Associates (1983)

19 AR000601* The identified inorganic indicator chemical in fish tissue was zinc, organic analyses is forthcoming. Bis(2-chloroethyl)ether was identified as a potential indicator chemical based on its presence in Army Creek and its accepted bioconcentration factor. Potentially exposed human and environmental receptors (plants and animals) are as follows: 1. persons trespassing on the site 2. persons residing or working downwind (to the north) of the site 3. aquatic biota in Army Creek/Pond 4. terrestrial flora and fauna living on site or seasonally using the site Monitoring activities have shown that the Artesian Water Company production wells, used for potable water supply in the area, have not been adversely affected by site-related contamination. The continued operation of the recovery well network will prevent them from becoming contaminated in the future. Identified potential human exposure routes included: 1. inadvertent ingestion of groundwater recovery well discharges (e.g., being splashed in the face), and surface water (e.g., falling into the pond) 2. inhalation of volatile organic compounds from groundwater recovery well discharges and surface water (e.g., while playing in or near the pond) 3. dermal absorption of contaminants from inadvertent exposure to recovered groundwater (e.g., being splashed by discharge) or surface water (e.g., falling into the pond) 4. fish consumption by recreational anglers To calculate the risk to public health, certain exposure estimates were made based on human activity patterns. - The ingestion rate of both surface water and recovery well discharges was set at 0.1 liter/day for a 70-kg adult and a 30- kg child. The absorption fraction was specified as 100 percent of all contaminants. - The inhalation rate was set at 1 m3/day for both a 70-kg adult and a 30-kg child. The absorption fraction was specified as 100 percent of all air contaminants. - The sediment ingestion rate was set at 50 mg/day for a 70-kg adult and a 30-kg child. - The dermal absorption exposure estimates were based on surface areas of :8,750 cm and 19,400 cm2 for 100 percent body exposure for a child and adult, respectively. Common to all evaluated scenarios, the exposure frequencies were six exposures in 30 years for adults and one exposure per year for six years for a child. Carcinogenic risk was based on an exposure duration of 30 years. Carcinogenic risk for a child was based on an exposure duration of six years. A lifetime was considered to be 70 years. 20 ARG006G5 The exposure estimate for ingestion of contaminated fish was set at 5.2 g/day which is the average consumption rate of freshwater fish by recreational anglers in Delaware. This exposure assessment assumes that 100 percent of the freshwater fish consumed by the receptor are taken from Army Creek/Pond. It is unlikely that a higher consumption rate will be realized based on the size of the creek and research conducted by the Delaware Division of Fish and Wildlife indicating "extremely low catches" in Army Creek. Toxioity Assessment Summary Cancer potency factors (CPFs) have been developed by EPA's Carcinogenic Assessment Group for estimating excess lifetime cancer risks associated with exposure to potentially carcinogenic chemicals (Table 7). CPFs, which are expressed in units of (mg/kg-day)~1, are multiplied by the estimated intake of a potential carcinogen, in mg/kg-day, to provide an upper-bound estimate of the excess lifetime cancer risk associated with exposure at the intake level. The term "upper bound" reflects the conservative estimate of the risks calculated from the CPF. Use of this approach makes underestimation of the actual cancer risk highly unlikely. Cancer potency factors are derived from the results of human epidemiological studies or chronic animal bioassays to which animal-to-human extrapolation and uncertainty factors have been applied. Reference doses (RfDs) have been developed by EPA for indicating the potential for adverse health effects from exposure to chemicals exhibiting noncarcinogenic effects (Table 7). RfDs, which are expressed in units of mg/kg-day, are estimatee of lifetime daily exposure levels for humane, including seneitive individuals. Estimated intakee of chemicals from environmental media (e.g., the amount of a chemical ingested from contaminated water) can be compared to the RfD. RfDs are derived from human epidemiological studies or animal studies to which uncertainty factors have been applied (e.g., to account for the use of animal data to predict effects on humans). These uncertainty factors help ensure that the RfDs will not underestimate the potential for adverse noncarcinogenic effects to occur. Risk Characterisation Summary Excess lifetime cancer risks are determined by multiplying the intake level with the cancer potency factor. These risks are probabilities that are generally expressed in scientific notation (e.g., 1x10'* or 1E-6). An excees lifetime cancer risk of IxlO'6 indicates that, as.a plausible upper bound, an individual has a one in one million chance of developing cancer as a result of site- related exposure to a carcinogen over a 70-year lifetime under the specific exposure conditions at a site. The summary of total potential carcinogenic risks (Table 8) shows that none of the exposure scenarios at this site, with respect to surface water and sediments, present an unacceptable risk to human health.

21 AROG0606 Table 7 Dose-Response Parameters for Indicator Chemicals Army Creek Landfill Mew Castle, Delaware

Carcinogenic Potency Chronic Factor Reference Dose l •• EPA Weight mg/kg/day mg/kg/day of Evidence Carcinogenic Chemical Oral •Inhl Oral •Inhl Classification

Znorganics Arsenic 0.001 50 A (1,0) Cadmium 0.0005 6.1 Bl (I) (water) 0.001 (food) Chromium A (I) (Trivalent or total) 1.0 (III) Iron Lead 1.4E-3 4.3E-4 B2 (1,0) Mercury 3E-4 B2 (1,0) Nickel 0.02 0.84 A (I) (Dust) Zinc 0.2

22 ARGG06G7 Table 7 Continued

Carcinogenic Potency Chronic Factor Reference Dose 1 •• EPA Weight mg/kg/day mg/kg/day of Evidence Chemical Carcinogenic Oral •Inhl Oral •Inhl Classification

organies Benzene 0.029 0.029 A (1,0) Benzo (a) pyrene B2 (1,0) Bis ( 2 -chloroethyl ) ether 1.1 1.1 B2 (1,0) 1 , 2-Dichloroethane 0.091 0.091 B2 (1,0)

• Inhalation ** A - Known human carcinogen Bl - Probable human carcinogen. Limited evidence of carcino-genicity in humans. B2 - Probable human carcinogen. Sufficient evidence of car- inogenicity in animals with inadequate evidence in humans. I - Inhalation O - Oral

23 &RGG06G8 Table 8 S' y of Total Potential carcinogenic Risks

Age Group Exposed Children Adults Media Scenario 6-11 yrs 70-yr life span Groundwater Recovery Inadvertent ingestion 1.2xlOE-8 5.3X10E-9 Well Discharges Inhalation of organics 7.2X10E-7 3.1X10E-7 leaving groundwater Dermal absorption 9.7X10E-7 9.2X10E-7 Sediment • Inadvertent ingestion 4 . 1X10E-9 1.7X10E-9 Surface Water • Inadvertent ingestion 6.5X10E-9 2.9X10E-9 Inhalation of organics 1.8X10E-7 7 . 6X10E-9 leaving surface water Dermal absorption 6.0X10E-8 5.7X10E-7 Fish •* Ingestion NC 7.7X10E-7

* Sediment and surface water risks were calculated using the highest pollutant concentrations detected during sampling. •• Estimated using calculated average pollutant concentration during sampling, accepted bioconcentration factor and 5.2 g/day consumption rate. NC These values could not be calculated due to a lack of sufficient information regarding fresh fish consumption for children 6-11 years old.

24 ARGG0609 The potential for health effects resulting from exposure to noncarcinogenic compounds is estimated by comparing an estimated daily dose to an acceptable level. If the ratio exceeds 1.0, there is a potential health risk associated with exposure to that particular chemical. The ratios can be added for exposures to multiple contaminants. The sum, known as a Hazard Index, is not a mathematical prediction of the severity of toxic effects, but rather a numerical indicator of the transition from acceptable to unacceptable levels. Table 9 presents a summary of the total potential Hazard Indices for the exposure scenarios previously discussed. Since none of the total Hazard Indices exceeds 1.0, there is no cause of concern for noncarcinogenic hazard to human health at the Army Creek site. Environmental Risks EPA conducted a survey of the aquatic life present in Army Pond which identified a very low number of species in the pond. In addition, 95 percent of those species found in the pond were pollution tolerant organisms, indicating poor water quality. Numeric surface water quality criteria have been developed by EPA and DNREC [promulgated Delaware Surface Water Quality Standards (DSWQS)] and are of primary utility in assessing acute and chronic toxicity effects in aquatic organisms. Contaminant-specific maximum levels have been established in addition to the narrative criteria for the protection of freshwater aquatic life. The following contaminants were.found to exceed the numeric criteria for freshwater aquatic life set by DNREC in the surface water: cadmium, chromium, iron, mercury, and zinc (Table 4). There are three potential sources of surface water contamination: 1. recovered groundwater discharged to the surface water 2. leachate seeps from the Army Creek Landfill 3. offsite/onsite surface runoff The average value for contaminants identified in the recovered groundwater discharges was computed. The only contaminant found to exceed the numeric DSWQS for protection of freshwater aquatic life in the discharge is iron (Table 4). This indicates that the source of cadmium, chromium, mercury and zinc is either the leachate seeps or surface runoff from the drainage area. The installation of the hydraulic barrier (cap) in accordance with the first Record of Decision will reduce the leaching of contaminante from the landfill and modify the flow of runoff in the area of the landfill surface (first operable unit). If the recovered groundwater is treated to reduce the concentration of iron (remedial objective of second operable unit) prior to being discharged to Army Creek/Pond, the numeric DSWQS known to be protective of the aquatic environment should be achieved. Actual or threatened releases of hazardous substances from this site, if not addressed by implementing the response action selected in this ROD, may present an imminent and substantial endangerment to the environment.

25 ARGG06IO Table 9 Summary of Total Potential Non-carcinogenic Hazard Indices

Age Group Exposed Children Adults Media Scenario 6-11 yrs 70-yr life span

Groundwater Recovery Inadvertent ingestion .000015 .0000013 Well Discharges Sediment • Inadvertent ingestion .00036 .000031 Surface Water • Inadvertent ingestion .0008 .00069 Fish Ingestion NC .0048

* Sediment and surface water risks were calculated using the highest pollutant concentrations detected during sampling. NC These values could not be calculated due to a lack of sufficient information regarding average fresh fish consumption for children 6-11 years old. If the Hazard Index exceeds 1.0, there is a potential health hazard associated with exposure to the medium.

26 ARG006II VII. DBSCRZPTIOlt OF ALT8.MfAT.IVES The Remedial Investigation found that neither the surface water nor the recovery well discharges present an unacceptable risk to human health or welfare; however, the most recent sampling results indicate that the discharges may be contributing to an excursion of the DSWQS numeric criterion for bis(2-chloroethyl)ether established for protection of human health via the fish consumption exposure route. The available data is insufficient to determine if the reported levels are representative of the character of the recovered groundwater or an anomaly; hence, chemical-specific treatment will not yet be proposed. The remedial objective of operable unit two is to ensure that the recovery well discharges do not exceed the applicable requirements set forth in the DSWQS that are protective of the designated uses of Army Creek/Pond. Based on historical and recent analyses, the level of iron in the discharges definitively contribute to an "in stream" concentration that exceeds the numeric criterion known to be protective of the aquatic environment. A reduction of iron prior to surface water discharge is therefore required. Four remedial alternatives (including No Action) were developed as possible response actions for providing a level of water quality in the recovery well discharges that is protective of the aquatic environment. Each alternative includes a chemical and biological monitoring plan. In the event that further monitoring finds the dischargee to be exceeding the numeric or narrative criteria listed in the DSWQS, a compliance program will be developed and implemented (excepting No Action). The [recovered] groundwater monitoring plan described in the Proposed Plan was incorrectly identified as being undertaken in compliance with RCRA Subpart F, 40 C.F.R. 264.100. Reference to the statute has been deleted from this document. Alternative fls No Action - Monitoring only Capital Cost: 0* Annual Operation and Manintenance (O&M) Costs: 0* Present Worth: 0* Months to implement: 0* The first operable unit Record of Decision requires that groundwater be extracted from the aquifer adjacent to the site. Groundwater ie currently recovered from the local aquifer by a series of wells which comprise a recovery well network* Under the No Action scenario thia recovered groundwater would continue to be discharged into Army Creek/Pond untreated. The calculated average concentration of iron being discharged from the recovery well network is in the range of 6,000 to 12,000 ug/L. This is well above the Delaware Surface Water Quality Standard of 1,000 ug/L considered to be protective of the aquatic environment. This alternative also includes long-term monitoring of the surface water, sediments and recovered groundwater quality to gauge the effectiveness of the remedy, and a wetland monitoring and evaluation plan consistent with the Record of Decision issued for the 27 6R0006I2 adjacent Delaware Sand & Gravel Site. Chemical and biological monitoring of treated groundwater effluent will be conducted consistent with NPDES requirements (to ensure that criteria and standards pursuant to Section 304(a) of the Clean Water Act are being attained). At least two surface water and sediment sampling events in Army Creek/Pond will be required to assess habitat quality: at five years after completion of the landfill cap (consistent with OU1 ROD) and at one year after pumping and treatment has ceased. The surface water and sediment sampling will include chemistry analyses and toxicity testing (using chronic surface water and sediment bioassays). Army Creek Landfill has affected the habitat (surface water and sediment) quality and the hydrology of Army Creek/Pond and its associated wetlands. The Army Creek watershed, previous to the existence of Army Creek Landfill, supported valuable wetland habitat. The wetland areas will be monitored to ensure that comparable habitat values will be maintained. Alternative 12s conventional Water Treatment Capital Cost: $1,874,250* Annual O&M Cost: 260,860* Present Worth: 3,900,000* Months to implement: 14* This alternative involves the construction and operation of a conventional precipitation water treatment plant. The water extracted by the recovery well network would be passed through a combination of unit processes including aeration (cascade aeration), precipitation (pH adjustment and polymer addition), and filtration (sand filtration) before being discharged to Army Creek/Pond. Support processes include sludge thickening and dewatering. Sludge generated by the treatment process will be sampled and disposed of appropriately. This plant is anticipated to reduce the iron concentration in the recovered groundwater from the current range of 6,000 to 12,000 ug/L to less than 5,000 ug/L, but not to the 1,000 ug/L target level. The treatment plant will reduce the volume of iron in the recovered groundwater discharge by reducing the concentration. The mobility and potential toxicity to aquatic life associated with iron in the recovered groundwater would be reduced slightly. This alternative also includes long-term monitoring of the surface water, sediments and recovered groundwater quality to gauge the effectiveness of the remedy, and a wetland monitoring and evaluation plan consistent with the Record of Decision issued for the adjacent Delaware Sand & Gravel Site. Chemical and biological monitoring of treated groundwater effluent will be conducted consistent with NPDES requirements (to ensure that criteria and standards pursuant to Section 304(a) of the Clean Water Act are being attained). At least two surface water and sediment sampling events in Army Creek/Pond will be required to assess habitat quality: at five years after completion of the landfill cap (consistent with OUl * All cost and implementation times are estimated.

28 AR000613 ROD) and at one year after pumping and treatment has ceased. The surface water and sediment sampling will include chemistry analyses and toxicity testing (using chronic surface water and sediment bioassays). Army Creek Landfill has affected the habitat (surface water and sediment) quality and the hydrology of Army Creek/Pond and its associated wetlands. The Army Creek watershed, previous to the existence of Army Creek Landfill, supported valuable wetland habitat. The wetland areas will be monitored to ensure that comparable habitat values will be maintained. The Army Pond habitat will be managed during groundwater treatment and for a period of five(5) years after cessation of groundwater treatment to ensure the dominance of species beneficial to fish and wildlife, and to control less desirable reed grasses (Phragmites spp.). Monitoring of plant speciee composition and implementation of a management plan will be reviewed by the appropriate state and federal natural resource managers. Alternative f3s Modified Conventional Water Treatment Capital Cost: $2,710,000* Annual O6M Cost: 294,000* Present Worth: 4,900,000* Months to implement: 14* In order to ensure achieving the 1,000 ug/L iron surface water standard in the recovered groundwater prior to discharging to Army Pond, modifications to the Conventional Water Treatment (Alternative 2) can be incorporated. This "modified" conventional treatment plant is Alternative 3. Preliminary engineering evaluations indicate that these modifications should satisfy the objectives; however, other modifications to the conventional precipitation water treatment plant might be equally effective and therefore acceptable. This alternative involves the construction and operation of a "modified" conventional precipitation water treatment plant. The water extracted by the recovery well network would be passed through a combination of unit processee including an influent flow equalization chamber, aeration (cascade aeration with a blower), precipitation (pH adjustment and polymer addition), sedimentation (settling and thickening chamber), and granular media filtration before being discharged to Army Creek/Pond. Support processes include sludge thickening and dewatering. Sludge generated by the treatment process will be sampled and disposed of appropriately. By meeting the contaminant-specific ARAR (iron DSWQS numeric criterion of 1,000 ug/L), the effluent from the treatment plant should be protective of the aquatic environment. The treatment plant would reduce the volume of iron being discharged into Army Creek/Pond and the mobility would also be reduced. The potential toxicity to aquatic life associated with iron in the recovered groundwater would be eliminated. The facility should be designed in such a manner that

* All cost and implementation times are estimated.

29 AR0006U subsequent modifications may be incorporated in the event that the characteristics of the influent (recovered groundwater) change. This alternative also includes long-term monitoring of the surface water, sediments and recovered groundwater quality to gauge the effectiveness of the remedy, and a wetland monitoring and evaluation plan consistent with the Record of Decision issued for the adjacent Delaware Sand & Gravel site. Chemical and biological monitoring of treated groundwater effluent will be conducted coneistent with NPDES requirements (to ensure that criteria and standards pursuant to Section 304(a) of the Clean Water Act are being attained). At least two surface water and sediment sampling events in Army Creek/Pond will be required to assess habitat quality: at five years after completion of the landfill cap (consistent with OU1 ROD) and at one year after pumping and treatment has ceased. The surface water and sediment sampling will include chemistry analyses and toxicity testing (using chronic surface water and sediment bioassays). Army Creek Landfill has affected the habitat (surface water and sediment) quality and the hydrology of Army Creek/Pond and its associated wetlands. The Army Creek watershed, previous to the existence of Army Creek Landfill, supported valuable wetland habitat. The wetland areas will be monitored to ensure that comparable habitat values will be maintained. The Army Pond habitat will be managed during groundwater treatment and for a period of five (5) years after cessation of groundwater treatment to ensure the dominance of species beneficial to fish and wildlife, and to control less desirable reed grasses (Phragmites spp.). Monitoring of plant species composition and implementation of a management plan will be reviewed by the appropriate state and federal natural resource managers. Alternative |4s Enhanced Conventional Treatment Plant Capital Cost: $3,344,000* Annual O&M Cost: 351,000* Present Worth: 6,000,000* Months to implement: 14* The "Enhanced" conventional water treatment plant employs even further modification to the Conventional Water Treatment plant (Alternative 2). Preliminary engineering evaluations indicate that the Enhanced Conventional Water Treatment plant would achieve iron concentrations far below the remedial action objective of 1,000 ug/L known to be protective of the aquatic environment. This alternative involves the construction and operation of an "enhanced" conventional precipitation water treatment plant. The water extracted by the recovery well network would be passed through a combination of unit processes including an influent flow equalization chamber, aeration (high velocity-nozzle aerator), precipitation (pH adjustment and polymer addition), sedimentation (settling and thickening chamber), granular media filtration and a * All cost and implementation times are estimated.

30 AROG06I5 catalytic/ion exchange polisher (using "green sand" zeolite) before being discharged to Army Creek. Support processes include sludge thickening and dewatering. Sludge generated by the treatment process would be sampled and disposed of appropriately. By meeting the contaminant-specific ARAR (iron DSWQS numeric criterion of 1,000 ug/L), the discharge from the treatment plant should be protective of the aquatic environment. The treatment plant would reduce the volume of iron being discharged into Army Pond and the mobility would also be reduced. The potential toxicity to aquatic life associated with iron in the recovered groundwater would be eliminated. This alternative also includes long-term monitoring of the surface water, sediments and recovered groundwater quality to gauge the effectiveness of the remedy, and a wetland monitoring and evaluation plan consistent with the Record of Decision issued for the adjacent Delaware Sand & Gravel Site. Chemical and biological monitoring of treated groundwater effluent will be conducted consistent with NPDES requirements (to ensure that criteria and standards pursuant to Section 304(a) of the Clean Water Act are being attained). At least two surface water and sediment sampling events in Army Creek/Pond will be required to assess habitat quality: at five years after completion of the landfill cap (consistent with OU1 ROD) and at one year after pumping and treatment has ceased. The surface water and sediment sampling will include chemistry analyses and toxicity testing (using chronic surface water and sediment bioassays). Army Creek Landfill has affected the habitat (surface water and sediment) quality and the hydrology of Army Creek/Pond and its associated wetlands. The Army Creek watershed, previous to the existence of Army Creek Landfill, supported valuable wetland habitat. The wetland areas will be monitored to ensure that comparable habitat values will be maintained. The Army Pond habitat will be managed during groundwater treatment and for a period of five (5) years after cessation of groundwater treatment to ensure the dominance of species beneficial to fish and wildlife, and to control less desirable reed grasses (Phragmites spp.). Monitoring of plant species composition and implementation of a management plan will be reviewed by the appropriate state and federal natural resource managers. VTTT. amntARY or vwm COMPARATIVE ANALYSIS OF ALTERNATIVES The following nine criteria were used in the evaluation of the remedial action alternatives for Operable Unit II at the Army Creek Site: Threshold Criteria 1) Overall protection of human health and the environment; and 2) Compliance with applicable or relevant and appropriate requirements.

31 AROG0616 Primary Balancing Criteria 3) Long-term effectiveness and permanence; 4) Reduction of toxicity, mobility, or volume through treatment; 5) Short-term effectiveness; 6) Implementability; and 7) Cost. Modifying Criteria 8) State/support agency acceptance; and 9) Community acceptance. A brief description of each of these criteria is provided in Table 10. Overall Protection of Human Health and the Environment Alternatives 13 and 14 will achieve the remedial objectives for thie second operable unit. Each of these alternatives provide for the extracted groundwater to be passed through a water treatment facility which will reduce the iron concentration to 1,000 ug/L (or leee in the caee of Alternative |4), which is known to be protective of the aquatic environment. The Conventional Water Treatment (Alternative 12) facility would reduce the iron concentration in the recovered groundwater from the current range of 6,000 to 12,000 ug/L to less than 5,000 ug/L, but not to 1,000 ug/L, which is the level known to be protective of the aquatic environment. compliance with ARARs Alternatives 13 and 14 will meet the contaminant-specific ARAR for surface water discharge to Army Creek/Pond by achieving a maximum iron concentration equal to or less than the criterion that has been established by DNREC pursuant to Section 303 of the Clean Water Act. Surface water quality criteria are "in stream" maximum concentrations that are used by the NPDES program to determine maximum allowable concentrations in surface water discharges. In accordance with the Delaware surface water quality standards, when calculating the maximum allowable discharge concentration for the protection of aquatic life (chronic toxicity), the effect of dilution is based on the lowest flow over a seven-day period with a recurrence interval of ten years. Since the upstream portion of Army Creek is considered to be an intermittent stream, little dilution effect can be calculated; therefore, the concentration of iron in the effluent must come close to meeting the maximum allowable "in stream" standards. In the event that activities undertaken in accordance with the monitoring plan confirm that the level of bis(2-chloroethyl)ether is contributing to the excursion of the applicable criterion or find that the characteristics of the recovered groundwater change so that the applicable surface water standards are not being met, a compliance

32 AR0006I7 TABLE 10

MIME EVALUATION CRITERIA 1. Overall Protection of Human Health and the Environment addresses whether or not a remedy provides adequate protection and describee how risks posed through each pathway are eliminated, reduced or controlled through treatment or engineering. 2. Compliance with ARARs: Whether or not a remedy will meet all Applicable or Relevant and Appropriate Requirements (ARARs) of Federal and State Environmental Statutes and/or provides grounds for invoking a waiver. Whether or not the remedy complies with advisories, criteria and guidance that EPA and DNREC have agreed to follow. 3. Long-Term Effectiveness and Permanence refers to the ability of a remedy to maintain reliable protection of human health and the environment over time once cleanup goals have been met. 4 . Reduction of Toxicity. Mobility or Volume is the anticipated performance of the treatment technologies a remedy may employ. 5. Short-term Effectiveness addresses the period of time needed to achieve the protection, and any adverse impacts on human health and the environment that may be posed during the construction and implementation period until cleanup goale are achieved. 6. Implementabil ity ie the technical and administrative feasibility of a remedy, including the availability of materials and services needed to implement a particular option. 7. Cost includes estimated capital , operation and maintenance, and net present worth costs. 8. State Acceptance indicates whether, based on its review of the RI/FS and Proposed Plan, the State concurs with, opposes, or has no comment on the identified preferred alternative. Acceptance indicates whether, based on its review of the RI/FS and Proposed Plan, the Community concurs with, opposee, or haa no comment on the previously identified preferred alternative. Community comments and the Agency's responses have been included in the Responsiveness Summary.

33 AR0006I8 plan will be developed and implemented. Action-specific ARARs, such as OSHA health and safety requirements, must be met at the treatment facility and will be further evaluated during remedial design activities. Alternative 12 will reduce the iron concentration in the recovered groundwater to less than 5,000 ug/L but will not attain the ambient water quality criterion of 1,000 ug/L which is known to be protective of the aquatic environment. Alternatives #2, #3 and 14 will meet the location-specific ARARs for protection and management of floodplains and wetlands pursuant to Federal Executive Orders 11988 and 11990 and State Executive Order 56. Long-term monitoring and wetland evaluation and management will meet the requirement to minimize the loss or degradation of wetlands, to restore and rehabilitate the wetland habitat; and to preserve the natural and beneficial values within the floodplain. Long-Term Effectiveness The long-term effectiveness of both alternatives #3 and 14 is anticipated to be good. The effectiveness will be maintained as long as the treatment plant constructed is operated and the landfill cap continues to function as a hydraulic barrier. The treatment of the recovered groundwater will be required until the recovery well network can be shut down or the extracted groundwater meets a level of water quality that is protective of the designated uses of Army Creek/Pond prior to treatment. Alternative 12 will only attain marginal effectiveness by reducing iron concentratione to less than 5,000 ug/L. The marginal effectiveness attained will be maintained ae long as the treatment plant constructed is operated and the landfill cap continues to function as a hydraulic barrier. Reduction of Toxicity, Mobility and Volume Alternatives |2, 13 and 14 use treatment to reduce the toxicity, mobility and volume of iron in the recovered groundwater. Both Alternatives 13 and 14 are equivalent in their reduction of the potential toxicity to aquatic life associated with iron in the recovered groundwater. Alternative 12 will reduce toxicity by reducing the concentration of iron, however, not by enough to eliminate the potentially toxic effect. Alternatives #4, |3, and #2, listed in order of effectiveness, each reduce the volume and mobility of iron released to the environment by reducing the concentration in the recovered groundwater prior to discharging to Army Creek/Pond. Short-Term Effectiveness Alternatives #3 and #4 would be expected to yield good short- term effectiveness with respect to the potential for chronic toxicity due to high levels of iron in the aquatic environment. Both the "Modified" and "Enhanced" water treatment facilities would achieve compliance with the surface water quality criterion (1,000 ug/L) prior to discharge to Army Creek/Pond within approximately two weeks

34 AR0006I9 of plant start-up. However, the overall impact of this reduction is expected to be only moderate during the short-term because the overall strategy also relies on the positive effect to be realized from the installation of the hydraulic barrier (cap) over the 44- acre landfill. Alternative #2 would be anticipated to yield moderate-to-low effectiveness with respect to the potential chronic toxicity to the aquatic environment presented by iron. Even after the facility achieved its performance standard, the effluent would not achieve levels known to be protective of the environment. Implementability Alternatives #2, 13 and #4 are equally implementable. The installation and operation of the water treatment facilities could be accomplished easily. The basic components conceptually included in all these alternatives are readily available and regularly installed by construction contractors. The operability of each of these alternatives is well understood and routinely carried out. The long- term monitoring plan included in each of the alternatives is also easily implemented.

COSt CERCLA requires selection of a cost-effective remedy (not merely the lowest cost) that protects human health and the environment and meets other requirements of the statute. Project cost includes all construction and operation and maintenance costs incurred over the life of the project. An analyeie of the preeent worth value of these costs has been completed for each alternative described in this Record of Decision, and is summarized in Table 11. Capital costs include those expenditures necessary to implement a remedial action. Annual operating costs are included in the present worth cost. The relative cost, in order of most to least is Alternative #4, 13, #2, and then II. Community Acceptance The Proposed Plan was released to solicit public comment regarding the proposed remedial alternatives on March 18, 1990. At that time a 31 day comment period was opened. A public meeting on the Proposed Plan wae held March 26, 1990, in New Castle, Delaware. Pursuant to the request of a citizen the public comment period was extended to May 2, 1990. Comments at the public meeting and during the comment period are referenced in the Responsiveness Summary included in this Record of Decision. state Acceptance The State of Delaware has not concurred with this selected Remedial Action.

35 AR00062G II. THE SELECTED P.BMBPY, Alternative 13s Modified Conventional Treatment - 1,000 ug/L iron performance standard. Capital Cost: $2,710,000 Annual Operation & Maintenance Costs: $294,000 Present Worth: $4,900,000 Based upon consideration of the requirements of CERCLA, the detailed evaluation of the alternatives, and public comments, both EPA and the State of Delaware have determined that Alternative I3 is the most appropriate remedy for Operable Unit II of the Army Creek Site. The objective of this alternative is to reduce the concentration of iron in the recovered groundwater to 1,000 ug/L prior to discharging to Army Creek/Pond. The overall goal of the remedial activities being taken with respect to the surface water at Army Creek is to attain the Delaware Surface Water Quality standards established pursuant to Section 303 of the Clean Water Act. In the event that activities undertaken in accordance with the monitoring plan confirm that the level of bis(2-chloroethyl)ether is contributing to the excursion of the applicable criterion or find that the characteristics of the recovered groundwater change so that the applicable surface water standards are not being met, a compliance plan will be developed and implemented. The combined strategy of providing treatment to the recovered groundwater prior to diecharge and installing a landfill cap over Army Creek Landfill to reduce leachate seepage into Army Creek (in accordance with ROD I) is expected to achieve an "in stream" water quality that supports the designated usee and is protective of the aquatic environment. This alternative also includes long-term monitoring of the treatment plant influent, effluent and Army Creek/Pond surface water and sediment quality to gauge effectiveness of the selected remedy, and a wetland monitoring and evaluation plan. The Army Pond habitat will be managed during groundwater treatment and for a period of five (5) years after cessation of groundwater treatment to ensure the dominance of speciee beneficial to fish and wildlife, and to control less desirable reed grasses (Phragmites spp.). A more detailed description of the selected remedy is provided in Section VIZ. The facility should be designed in such a manner that subsequent modifications may be incorporated in the event that the characteristics of the influent (recovered groundwater) change. It should be recognized that minor changes to the selected alternative may be made during design as long as the performance standard is achieved. These changes in general will reflect the usual modification resulting from the engineering process.

3C. STATUTORY DETERMINATIONS EPA's primary responsibility at Superfund sites is to undertake remedial actions that are protective of human health and the environment. In addition, Section 121 of CERCLA, as amended, 36 AR00062I establishes several other statutory requirements and preferences. These specify that when complete, the selected remedial action for this site must comply with applicable or relevant and appropriate environmental standards established under Federal and State environmental laws unless a statutory waiver is granted. The selected remedy also must be cost-effective and utilize treatment technologies or resource recovery technologies to the maximum extent practicable. Finally, the statute includes a preference for remedies that permanently and significantly reduce the volume, toxicity or mobility of hazardous wastes. The following sections discuss how the selected remedy for this site meets these statutory requirements. Protection of Human Health and the Environment The selected remedy protects the environment by providing onsite treatment of recovered groundwater prior to discharging to Army Creek/Pond. The combined remedial strategy of capping the landfill (in accordance with ROD 1), which will reduce landfill leachate seeping directly into Army Creek/Pond, and operating a treatment facility to reduce the concentration of iron in the recovered groundwater prior to discharging will achieve a level of water quality that is protective of the environment. The baseline human health risk assessment determined that there is no unacceptable risk to human health or welfare with respect to the surface water or sediments at the site. The exposure levels are well within the 10 to 10 range within which EPA manages potential carcinogenic risk and the Hazard Indicee for non-carcinogens are much less than one. The remedy selected in the first Record of Decision will mitigate the risk presented to human health via groundwater ingestion. Attainment of Applicable or Relevant and Appropriate Requirements The selected remedy will attain all applicable or relevant and appropriate requirements for the site surface water and associated wetlands, the contaminants in the surface water, and the actions that will be implemented. The ARARs are presented below. Action-Specific ARARs Water Air Resources Act (7 Delaware Code Chapter 60, 1983) The following State regulations are promulgated pursuant to Section 6010 of Chapter 60: rDelaware! Surface Water Quality Standards (1990) Sections that clearly apply:

* In accordance with CERCLA Section 121(e) no permit shall be required for actions conducted entirely onsite but substantive requirements must be met.

37 AR000622 Regulations Governing the Land Treatment of Wastes (1988) Section 4.1(a)(iii): Surface waters must be free from any pollutants which may interfere with attainment and maintenance of designated uses. Section 9.2: General provisions prohibiting acute or chronic toxicity to aquatic life, adverse effects on human health from ingestion of contaminated aquatic organisms. Section 9.3: Iron requirement of 1,000 ug/L for protection of aquatic life against chronic toxicity. TState") Regulations Governing Control of Water Pollution (1983) Section 3.01: Discharge of any pollutant from point source to surface water requires permit.* Treatment plant sludge is subject to requirements of Part III(B) Section 301 pertaining to transportation, and treatment disposal. Regulations Governing Solid Waste (1988) (Section 6 pertains to industrial landfills) Section 6.D.3.f: Residuals from on-site leachate treatment system must be sampled and analyzed for hazardous waste characteristics per Delaware Hazardous Waste regulations. Section 6.K.I.a: post-closure care for 30 years. Section 6.K.l.e: action necessary to mitigate threat to human health or the environment if evidence of contaminant release. Erosion & Sedimentation Control (7 Delaware Code Chapter 40) Erosion & Sedimentation Control Regulations (1989) General state criteria: E&S plan must be developed and followed during construction of the water treatment plant to prevent increased sedimentation or accelerated erosion into Army Creek. Clean Water Act (33 U.S.C. § 1251 fit sea.) Pursuant to Section 402 of the Clean Water Act, 33 U.S.C. § 1342, any discharge of pollutants from a point source to waters of the United State requires a National Pollutant Discharge Elimination System (NPDES) permit. The NPDES permit must contain conditions that are protective of human health and the aquatic life.

In accordance with CERCLA Section 121(e) no permit shall be required for actions conducted entirely onsite but substantive requirements must be met.

38 AR000623 mi pant—Specif Ic ARARS Hazardous Waste Management Act (7 Delaware Code Chapter 631 Regulations Governing Hazardous Waste (1988) Section 262.11: Hazardous waste determination must be made on sludge generated by treatment of discharges. Clean Water Act (33 U.S.C.S 1251 et seq.1 Pursuant to Section 303 of the Clean Water Act, 33 U.S.C. § 1313, the State of Delaware has coupled federal Ambient Water Quality Criteria [established under Section 304(a)] with designated uses (described in Section 101) to determine Delaware Surface Water Quality Standards (DSWQS). The recovered groundwater must receive treatment to reduce the concentration of chemical constituents to a level that will not exceed DSWQS that support or are protective of Army Creek's designated uses. other criteria, advisories or guidance to be considered for this remedial action (TBC'sl State Executive Order 56 on Freshwater Wetlands (1988) (Including Governor's Roundtable Report on Freshwater Wetlands, 1989) General policy to minimize the adverse effects to freshwater wetlands resulting from the construction and operation of the treatment plant, including the resultant discharges. Federal Executive Order 11988. Floodplain Management. 40 C.F.R. Part 6. Appendix A Action must avoid adverse effects, minimize potential harm, restore and preserve natural beneficial value. Federal Executive Order 11990. Protection of Wetlands. 40 C.F.R. Part 6. Appendix A Action must minimize destruction, loss, or degradation of wetlands and preserve and enhance the natural and beneficial valuee of wetlands. The wetlands management plan will act to preserve the natural and beneficial valves-of the wetlands to the wildlife be ensuring that the perimeter of the Army Creek/Pond is recolonized by indigenous species after the recovery wells are phased-out or shut down. Cost-Effectiveness EPA and the State believe the selected remedy is cost-effective in mitigating the risk posed by the surface water adjacent to the landfill. The selected alternative includes the least costly remedy which will effectively achieve our remedial objective for this second operable unit.

39 &R000621* Utilisation of Permanent Solutions Employing Alternative Technologies to the Maximum Extent Practicable The selected remedy is the most appropriate solution for this operable unit and represents the maximum extent to which permanent solutions and treatment can be practicably utilized. Both alternatives §3 and |4 meet the threshold criteria of being protective and achieving ARARs and are equal in effectiveness with respect to long-term effectiveness and permanence; reduction in toxicity, mobility and volume through treatment; short-term effectiveness and implementability. Since alternative #3 and alternative #4 are equally effective and alternative #3 is less costly than alternative #4, alternative 13 was selected on the basis of being more cost-effective. The proposed selection of alternative 13 was well received by the State and community. Preference for Treatment This preference is satisfied since treatment is the principal element of the chosen alternative.

40 AR000625 w H

AR000626 AR000627 AR000628 EXHIBIT 4

Army Creek Remediation Scope of Work-2

Army Creek Landfill Superfund Site New Castle County Delaware

ARG00629 -1-

ARMY CREEK REMEDIATION SCOPE OF WORK-2 TABLE OF CONTENTS

SECTION TITLE PAGE 1.0 Introduction 1 2.0 Construction of the Army Creek 2 Treatment Plant 3.0 The Army Creek Water 3 Treatment Plant 3.1 Labor 3 3.2 Materials and Supplies 5 3.3 Utilities 7 4.0 The Army Creek Recovery Wellfield 7 4.1 Background 7 4.2 Wellfield Operation 8 5.0 Monitor Point System 11 5.1 Background 11 5.2 Tasks 12 5.3 Anticipated Scope and Duration 14 5.3.1 Use of Existing Monitor Points 14 5.3.2 Additional Monitor Points 15 5.4 Five Year Evaluation Report 17 5.5 Army Creek/Pond Surface Water and Sediment Monitoring Plan 17 6.0 • Methodology for System Phaseout 18

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6.1 Backgound 18 6.2 Implementation 19 .6.3 Phase-Out, Monitoring and 20 Re-Start Procedures 6.4 Management of Army Pond Habitat 22

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1.0 Introduction

This document is Scope of Work-2, Exhibit 4 to the Army Creek Consent Decree. This Scope of Work is intended to identify and outline the principal items required to implement Work-2. The descriptions of the three major components (Treatment Plant, Recovery Wellfield and Monitor Point System) will, as necessary, be specified in greater detail in a Work Plan subsequently to be submitted to EPA Region III.

These components of Work-2 were specified by EPA Region III as the preferred means to restore groundwater quality that, in EPA's view, has been affected by conditions at both the Army Creek and Delaware Sand & Gravel Landfills. Various studies conducted by EPA and private parties have identified iron as the principal "contaminant of concern" in the recovered groundwater with respect to the feasibility of discharging this recovered groundwater to Army Creek. These studies have indicated that elevated iron levels — ranging from 6-to-12 ppm or an average of 5 ppm above background — are attributable to the presence of landfill leachate in the groundwater.

Accordingly, the Recovery Wellfield component is designed to control groundwater that may contain unacceptably high levels (under drinking water standards) of either organic or inorganic compounds. That component is also designed to route those waters to the Treatment Plant, which removes iron to

AR000632 -2-

levels specified by ROD-2 and then returns the restored water to the environment.

The Monitor Point component will gauge the effectiveness of the remedial measures. Recovery well flow rates must be measured and compared with groundwater level readings from various monitor points to determine the need for Recovery Wellfield adjustments (e.g.. rehabilitation, flow rate adjustments or new recovery well locations) that will optimize system efficiency. These data must in turn be analyzed in relation to water quality measurements that, taken together, assess the manner in which the other remedial measures (principally, construction of surface caps and removal of contaminated soils) can be combined with the System to optimize restorative efficiencies. Accordingly, each component of the system, as well as other remedial measures taken at Army Creek and DS&G, is integral to restoration of groundwater quality.

2.0 Construction of the Army Creek Treatment Plant

Construction of the Army Creek treatment plant will be in accordance with the schedule to be included in the Work Plan to

AR000633 -3- be submitted by the County. Attachment A to this Scope of Work will be a set of the plans and specifications for the plant that is to be constructed upon approval of these plans by EPA prior to entry of the Consent Decree. The performance standards referenced in Section VI.C.I of the Consent Decree and ROD-2 shall be those described in Attachment C hereto and pertinent to the operation and performance of the treatment plant.

3.0 The Army Creek Water Treatment Plant

The Army Creek treatment plant shall be a 24 hr/day operating facility. As such, there will be a need to oversee the plant to assure uninterrupted treatment and to replace and repair component parts as necessary.

3.1 Labor

Labor incident to these functions includes inhouse or outside personnel involved in plant operation and coordinating the scheduling for the repair or replacement of component parts of the physical plant or the chemical processes. Other items include:

AROG0631* -4-

o Equipment operators to operate machinery incidental to the operation of the treatment plant. This may include truck drivers to load/unload dumpsters or incoming bulk chemical supplies.

o Electricians will be utilized to trouble shoot and repair all electrical related problems associated with the day-to-day operation of the treatment plant.

o Mechanics will be utilized to service all mechanical devices such as valves and motors in support of the daily operation of the system.

o All labor categories, whether from the laboratory or operations staff, will require technical direction from management, i.e.. engineers, chemists and supervisors. o From time to time it will be necessary to retain consultants or outside contractors to adjust or "fine tune" the operation or components of the operation/building, recommend changes to trouble shoot problems or provide other services outside the capabilities of New Castle County.

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3.2 Materials and Supplies

Materials and supplies include expendable items and components necessary to effect repairs or replacements for day-to-day operation of the treatment plant. It can also include rental of machinery or equipment to accomplish various tasks. Other items include:

o The chemicals used in the treatment process. This is projected to consist of polymer, lime and hydrogen peroxide but may include other new or more cost effective materials as they become available.

o Expendable items such as oil, paper, soap, gaskets, seals, pumps, motors or any other mechanical component requiring replacement.

o Sludge handling and hauling would include not only the plant's filter processes but also the lease/purchase of the dumpster and the special truck employed to drag, lift and dump the dumpster. Transport of the sludge to its final point of deposition would include such items as gasoline and general operating expenses of the

AROG0636 -6- vehicle and fees incurred in connection with disposal of the sludge at a landfill or via some alternative disposal method.

There will be a requirement to service the waste holding receptacle for lavatory and washrooms used by plant personnel.

Laboratory services, whether performed by New Castle County or an outside contractor, to measure physical/chemical parameters of plant effluent.

Vehicle support will involve the vehicles utilized in any assignment related to the treatment plant. This may include trades trucks (e.g.. welder or mechanic) or vehicles used by supervisory personnel.

Additional materials may be required to implement alternations in the treatment process following recommendations for trouble shooting or fine tuning the system.

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3.3 Utilities

Utilities such as electricity and water are an integral part of the treatment plant operation. Electrical service must be maintained in order for pumps, presses, sensors, telemetering and atmospheric controls to operate. A telephone must be installed to maintain communications. A potable water source must be provided for drinking and wash water.

4.0 The Armv Creek Recovery Wellfield

4.1 Background

The original recovery wellfield was drilled and put into service in 1973. Regular and continual monitoring of wellfield performance, adjusting of pumping rates, and modeling has resulted in two redesigns of the recovery wellfield. The first took place in 1981 when five outlying recovery wells were abandoned and five new wells drilled closer to and in the Army Creek Landfill. Recent recovery well performance analysis resulted in the shutdown/disassembly of RW-14 and indicated that installation of a recovery well near the western side of the Army Creek Landfill is now appropriate. Due to the dynamic nature of the locally controlled groundwater system, the recovery wellfield is continually monitored to assess its capabilities in restoring groundwater quality. It is expected

AROG0638 -8- that recovery wells will be added, subtracted or refitted as conditions in the area change. The County shall not add any well to the recovery well network for the purpose of diluting the concentration of any contaminant in the influent to the treatment plant.

4.2 Wellfield Operation

Operational data has revealed the need to periodically "rehabilitate" or restore the efficiency of each pumping well. Efficiency of the wells is measured by observing the change in specific capacity. As specific capacity decreases, it is an indication that the gravel pack, screen, and riser pipe are becoming clogged with colonies of iron loving bacteria. The well and pump must then be inactiviated, disassembled and physically/chemically cleaned. Typically the need to perform this work occurs every five-to-six months.

Tasks associated with wellfield operation are as follows:

o Pumping rates and water levels shall be recorded in the field weekly to assure efficient operation of the wellfield and thereby optimize groundwater : quality restoration. Field data is computerized for efficient storage and retrieval. Data can be

ARG00639. -9- recalled in tabular form and as graphs to support reporting requirements.

Water quality data shall be collected and analyzed for trends.

All data received shall be subjected to quality control procedures and evaluated for pumping trends, further analysis, or the need to physically adjust the system.

From time to time it becomes necessary to embark upon efforts to predict wellfield performance. This is accomplished by applying existing data to digital models of the wellfield.

Miscellaneous Geoscience tasks are occasionally required to define aquifer parameters, soil characteristics or perform related special studies of the area incluenced by the pumping wells.

The wellfield electric system must be kept intact and in good working order. This includes inspecting the components (wires, power poles, control boxes and transformers) for vandalism or

AROG06l*G -10- other destructive losses and making repairs or replacements when necessary.

Recent modeling predicted the utility of drilling a new well on the western end of the wellfield. This effort will require consulting services for well design and inspection, the retention of a drilling contractor to drill and equip the well and an electrical contractor to bring power to the new well.

Approximately semi-annually, the wellfield's efficiency is reduced to the point where it becomes necessary to disassemble and physically/chemically clean each well, pump, riser pipe and discharge line assembly. This is accomplished utilizing the services of a drilling contractor. The contractor can provide the equipment and skills necessary to "rehabilitate" the wellfield.

Components of the wellfield system such as electrical control boxes, fuses, pumps, motors, discharge lines and submersible wire must be frequently inspected, and repaired or replaced as needed. When possible, spare parts and/or new

AROQ06U.1 -11-

replacement parts are stocked by New Castle County or are obtained from an outside contractor.

o The treatment of the disassembled well requires dosages of chemicals to loosen bacterial colonies choking the screen and gravel pack.

o The operation and rehabilitation of the wellfield is overseen by a professional geoscientist. This consultant service assures creditable data gathering and interpretation and the drilling contractors' performance to restore efficiency to the wellfield. o Roads must be kept passable to assure access to the wellfield.

5.0 Monitor Point System

5.1 Background

Since 1972, over 200 monitor points have been installed around and on the site. Through the years, many have been abandoned or fallen victim to nature, vandalism, or commercial development. Approximately 80 points remain (depicted on Attachment B) and this system has provided an approximate base of data points from which to appraise the restorative status of

AR0006t*2 -12-

the groundwater regime via the gathering of field data, creation of piezometric maps and computer modeling of groundwater flow components. Work-2 as defined in the Consent Decree contemplates an expanded monitor point system that will be utilized to measure groundwater conditions over a wider geographic area. These data will be used to assess the extent to which this System and other remedial facilities at Army Creek and DS&G are restoring groundwater quality; evaluate the need for further realignment of the recovery well system; and make determinations concerning phaseout of the recovery well system. All County recommendations regarding the Phase-Out, Monitoring and Re-Start Procedures in § 6.3 are subject to EPA approval.

5.2 Tasks

The following tasks will be included in this effort:

o Review of historical data and computer modeling to determine optimum configuration of expanded monitor point system.

o Labor and materials to re-establish former monitor points and drill new points, as determined by optimum configuration.

AROQ06U -13-

Ongoing collection of field data on recovery well quality parameters of treatment plant influent and effluent, water levels and/or water quality at various monitoring points, including those tasks set out in Attachment C hereto. In addition to chemical monitoring, biological monitoring will be conducted as set out in Attachment C.

Ongoing analysis and/or computer modeling of field data to assess requirements for optimum restorative configuration of the System.

Prepare and submit a Five Year Evaluation Report (FYER), five years after the Army Creek Landfill cap has been completed. The FYER will contain monitoring data, interpretation and technical recommendations relating ~o necessity of upgradient controls and the establishment of a recovery well phase out plan.

Labor and materials to reconfigure, down-scale or shutdown the recovery well system in accordance with data analysis. All tasks will be undertaken by the County and resulting data submitted to EPA. Recommendations for any modification to the

AR0006H . -14-

existing system will be submitted to EPA for approval.

5.3 Anticipated Scope and Duration

5.3.1 Use of Existing Monitor Points

Referring to Attachment B, the County presently takes weekly water level readings in the following 19 wells: AWC 2, 6, 7, G3, K7 RW 1, 4, 9, 10, 11, 12, 13 Wells 1A, 27, 28, 29, 31, 41, 42 The County presently takes monthly water level readings in the following 51 wells: Layne TW 134 DGC-1, 4, 2S, 3S, 6, 7S, 9S points A-l, 2, 4, 8, 9 B-3, 4, 12, 18 RW-14 S-l Wells 3A, 5A, 18, 20, 22, 24, 25, 26, 30, 32, 33, 34 38, 40, 44, 45, 49, 54, 56, 57, 58, 61, 63, 65, 66, 67, 68, 70, 71 Well points presently located in the "footprint" of the Army Creek surface cap will be eliminated. Prior to initiation of construction of the surface cap, a determination will be made by EPA on the need for installing water level monitoring points into the landfill. EPA will confer witii the County and the Private Settlors prior to making this determination. -15-

The County will continue the program of water level monitoring •(which includes preparation of monthly piezometric surface maps of the subject area) for purposes, inter alia, of assessing the extent to which the surface cap is restoring groundwater quality. Weekly water level readings as specified above (and for any new monitor points installed into the landfill) will continue for one year after construction of the Army Creek surface cap. Thereafter, these points also will be measured monthly absent conditions that necessitate continuation of water lev.el monitoring on some greater frequency. This information will provide the data base necessary to evaluate the need to rehabilitate individual wells, reconfigure the recovery well network, and utilize upgradient controls, consistent with ROD-l.

5.3.2 Additional Monitor Points

A well installation and monitoring program will also be implemented to provide data that will aid in determining recovery well realignments that may be necessary to optimize the system's efficiency at restoring groundwater quality and preparing evaluations on system phase-out in accordance with § 6. In general, it is anticipated that new wells may be installed where: (1) there are no current monitor points able to assess the efficiency of remedial actions at the Army Creek or DS&G sites, including the effectiveness of the recovery well -16-

system; (2) re-location of well points onto property owned or controlled by the County will achieve comparable data collection while avoiding long-term access issues that may affect wells presently located on private property; and (3) such other monitoring activities as may be necessary to assess the impact of commercial, industrial and residential development of nearby areas on the existing groundwater flow patterns for which the recovery well system is presently designed.

Any new wells placed downgradient of the Army Creek Landfill will be monitored monthly for water levels. Wells in categories (1) and (2) above will also be sampled and analyzed quarterly for total VOC's and those substances for which primary drinking water standards have been established. See Table A in § 6.2. All of the above monitoring activities will be undertaken until phase-out of the system is implemented in accordance with § 6.2, after which monitoring will be undertaken as specified in § 6.3.

As part of the Work Plan or as a separate submission within 30 days after entry of the Consent Decree, the County will submit a detailed Groundwater/Recovery Well Operation and Maintenance and Monitoring Plan-Phase I (O&M-PHI) to EPA for review and approval. The O&M-PHI plan shall contain a discussion of the data requirements that will be necessary to ensure that a complete evaluation of the effectiveness of Phase I activities

AR0006U7 -17-

described in ROD-l can be made. The O&M-PHI plan must describe how the Settlors intend to acquire all data that will be required to develop the Five Year Evaluation Report and to meet the requirements contained in this description of Work-2 (i.e.. criteria used to determine when recovery well rehabilitation is required).

5.4 Five Year Evaluation Report •>

Within 30 days after the fifth anniversary of the completion of the installation of the landfill cap, the County shall submit a Five Year Evaluation Report (FYER) to EPA for review and approval. Upon EPA approval, all established standards and methodologies incorporated in the FYER will become the performance standards required prior to phaseout or cessation of the recovery well network.

5.5 Armv Creek/Pond Surface Water and Sediment Monitoring Plan

At five years after completion of the Army Creek surface cap and at one year after pumping and treating has ceased, the County will collect from Army Creek/Pond surface water, in the vicinity of the treatment plant, and from sediments in Army Pond samples on which Priority Pollutant scans will be conducted and which will be subjected to surface water and sediment -18-

bioassays. Additional testing may be required if there is obvious degradation of Army Creek/Pond surface water.

6.0 Methodology For System Phase-out

6.1 Background

ROD-l specified (at p. 11) as follows:

The recovery well system will be evaluated in terms of both the flow system and water quality for a period of five years after the cap is installed or after the waste is excavated. If primary drinking water criteria levels are not met within this evaluation period, alternate concentration levels (ACL) will be considered. The ACLs will be based on an evaluation to define if sufficient attenuation will be achieved downgradient of the Army Creek Landfill, so that drinking water criteria levels will be met at any potential receptors. These ACLs will be applied at the recovery wells or the property boundary. When the ACLs are met, the recovery well system could be phased out.

6.2 Implementation

To implement this methodology, the County may utilize all available data, including water level and water quality data collected and analyzed in accordance wi^h § 5.3 hereof. At any time after the period of five years following installation of the Army Creek surface cap, the County may prepare and present to EPA an evaluation of these data. If primary drinking water criteria (as set out at in Table A overleaf) are met in the

AR0006t*9 Tnofganiea s

0.06 1 0.010 0.06 046 OJJOt (MN). 10 0.01 046

Organics;

(s) (1,3.4.10, 1 7- 1,4. 0.0008 (1 0.004 (1.1.1-Trtcn.wo^, 2-Hi (A- 0.1

0.006

0.1

0.01 (OT01SJ

0.10 mg/t

AR00065G Organicst

CAS MB. level to me/i

71-43-2 0406 75-01-4 0.001 0406 107-00-a 0.001 Tf-01-4 Ti 0406 1,1 0.007 71 1,1,1 0.078

Source: 40 C.F.R. SS 141.1Kb), 141.12, 141.61U)

ARQG0651 -19- boundary wells at that time, the system may be phased out in the manner described in § 6.3 hereof.

If the primary drinking water criteria are not met in the boundary wells at that time, the County may prepare and present to EPA an evaluation of alternate concentration levels ("ACLs"). This evaluation will examine whether, after phase-out of all or some part of the system, there will be sufficient attenuation of those substances for which primary drinking water criteria are published such that these criteria will be met in the Artesian Water Company ("AWC") water distribution system located at Llangollen Estates. The County may implement, upon EPA's approval, phase-out of all or part of the system in accordance with § 6.3 if this evaluation shows that: (1) any failure to meet primary drinking water criteria in AWC's Llangollen water distribution system should not be due to the proposed phase-out of the recovery well system, and (2) monitoring and re-start procedures under § 6.3 (or as the County may in the evaluation propose that they be altered) should be adequate to prevent any such failure in the event ACLs are initially set at inappropriate levels. If necessary, • substance-specific ACLs for the designated wells will, in accordance with ROD-l, be determined by EPA on the basis of the data presented in any such evaluation.

AR000652 -20-

In the event EPA disagrees with any such evaluation, the County may invoke the dispute resolution procedures set out in § XVIII of the Consent Decree. In the event the County does not contest EPA's position on an evaluation or in the event dispute resolution proceedings are resolved adversely to the County, it may submit another such evaluation not sooner than six months thereafter. The same procedure shall apply to all subsequently submitted evaluations. In the event of a partial phase-out, the County may at any time thereafter submit an evaluation supporting phase-out of additional components or of the balance of the system, as appropriate.

The five-year evaluation requirement shall not preclude any decrease in recovery well locations, flow rates and the like that may be warranted by groundwater conditions. No such changes shall be made without prior EPA approval, and any such changes shall not relieve the County of any other obligations, including submission of the FYER.

6.3 Phase-Out. Monitoring and Re-Start Procedures

Upon EPA's concurrence that the County's evaluation warrants a full or partial phase-out of the system, the County will, for the first quarter following shutdown, undertake bi-weekly monitoring for those substances on Table A in such monitoring or recovery wells that are determined to be best suited to

ARGG0653 -21- gauge the hydrogeologic impact of the shutdown in relation to AWC's Llangollen system. The County's recommendations in this respect will be subject to disapproval by EPA. In the event sampling data collected during the first quarter do not result in re-start of the system, monitoring for the same parameters in the same wells will be undertaken on a monthly basis for the next 12 months. In the event sampling data collected during that 12-month period do not result in re-start of the system, monitoring for the same parameters in the same wells shall continue on a quarterly basis for up to five years thereafter. This monitoring may be discontinued at an earlier date, with the concurrence of EPA, on the basis of field observations which indicate that monitoring at that level is no longer necessary.

In the event of a phase-out, the County shall maintain the recovery wells and/or the treatment plant in such condition that any wells shut down in a partial phase-out or (in the event of a complete phase-out) the overall system can be re-started within 45 days. This requirement shall apply for the period of time the County is required to-continue groundwater monitoring.

EPA may seek a re-start of all or part of the system after a partial or complete phase-out in accordance with the terms and conditions of § XXI (COVENANT NOT TO SUE) of the Consent Decree,

AROOQ65U -22-

6.4 Management of Army Pond Habitat

During the continued discharge of treatment plant effluent into Army Pond, the County will semi-annually inspect Army Pond and an area 50 yards beyond its present limits, except for areas on which the surface cap is constructed (hereinafter referred to, only for purposes of this Scope of Work-2, as the "Army Pond habitat"), and report to EPA on the types of vegetation in the habitat. For two years following cessation of plant discharge to Army Pond, the County will semi-annually measure Army Creek and Pond water levels as well as continue to conduct inspections of vegetation in the habitat. If during this two-year period Army Creek and Pond water levels recede so that associated wetland vegetation is dewate_ed and unvegetated substrate is exposed, inspection frequency will be increased to quarterly (excepting winter season).

Ideally, these transition areas, should they occur, will be naturally recolonized by already indigenous species which are of ecological value to fish and wildlife. In the event that these transition areas begin to be colonized by less desirable reed grasses (Phragmites spp.), the County shall implement an active management plan in an effort to r.aintain comparable ecological value. This management plan, to be included in the long-term operation and maintenance plan, may include reseeding

&RGQ0655 -23- and active measures, of reasonable scope-- in relation to vegetation in the surrounding area, to control colonization of reed grass.

If after two years the Army Creek and Pond water levels do not recede and create the conditions described above, or transition areas are naturally recolonized by vegetation of ecological value, the inspections will be conducted annually for three additional years. In the event that active management is required within the first two years following recovery well shutdown, an additional three years of Management in accordance with the plan will be undertaken.

&RGG0656 DUNN GEOSCICNCI CORPOIATION •ANortltwev LOM North Lotham. N.Y. 12110 pem««cnvt • wtu. uoomoiw OCUUMUW 4AMO A 4*W(U STUOT STAT¥ OF OCUUf AM

•an: 5^^000657 ATTACHMENT C

A. The discharge from the treatment facility shall be monitored as follows:

Effluent Parameter Monitoring Reguirement Measurement Sample Frequency Type Flow Continuous Recording/ Totalizing Total Suspended Solids Once/week Composite Iron (Total) Once/week Composite pH Once/week Grab In addition, the County shall conduct quarterly bioassays and Priority Pollutant scans on the effluent for one year after installation of the Army Creek surface cap. Thereafter, bioassays will be conducted quarterly and Priority Pollutant scans annually in accordance with Section 6.3 of this Scope of Work. Biomonitoring shall be conducted using EPA test method 1002.0 Ceriodaphnia Survival and Reproduction Test on 100% effluent from discharge and a control sample. The source of the control shall be Artesian Water Company Well Number 7 located in the Llangollen Wellfield or an alternate source as approved by EPA. The testing procedure is outlined in the EPA publication Short Term Methods for Estimating the Chronic Toxicitv of Effluents and Receiving Waters to Freshwater Organisms (EPA/600/4-85/014, December 1985). The results shall be reported according to EPA/600/4-85/014, Section 10, "Report Preparation," 45 days after completion of the testing procedure. Based on a review of the results of the biomonitoring, EPA may require periodic Priority Pollutant scans of both the effluent and the control. The County may propose, and, upon EPA approval, implement revisions to the testing procedures specified above. The Student's T Test shall be used to determine whether differences in control and effluent biomonitoring data are significant. Toxicity of the effluent will be demonstrated if either the survival or reproductability rates for the discharge sample are significantly less than, at the 95 percent

AR000658 -2-

confidence level, the rates for the control sample. If any one test indicates the effluent is toxic, a second and third set of samples shall be collected and tested for toxicity within the following 60 days. If toxicity is encountered twice in a 90-day period, the County shall submit for approval, within 60 days after completion of the second testing procedure, a plan for conducting a toxicity identification and reduction evaluation. The results of the toxicity reduction evaluation shall be submitted in accordance with a schedule approved by EPA. B. The quantity of effluent discharged from the wastewater treatment facility shall not exceed the design capability of the facility, as approved by EPA. The discharge from the treatment facility shall not exceed the effluent limitations set out on the table appearing on the following page. C. Monitoring results obtained during the previous one (1) month shall be summarized for each month and reported on a Discharge Monitoring. Report Form (EPA No. 3320-1), postmarked no later than the 28th day of the month following the completed reporting period. The first report is due at the end of the first month following approval of the Consent Decree. Signed copies of these reports shall be submitted to EPA and to the State at the following address: Pollution Control Branch Delaware Department of Natural Resources and and Environmental Control Division of Water Resources R&R Building, P.O. Box 1401 Dover, Delaware 19903 (302) 739-5731 Knowingly making any false statement on any such report may result in the imposition of criminal penalties as provided for under 7 Del. C. § 6013 and 18 U.S.C. § 1001. D. Pripr to the startup of any treatment equipment, the services of a Delaware certified sewage treatment plant operator shall be obtained for the operation and maintenance of the equipment. The operator shall, at a minimum, be licensed at the level necessary to comply with the State of Delaware Regulations for Licensing Operators of Wastewater Facilities, as revised. E. Adverse Impact The County shall take all reasonable steps to minimize any adverse impact to the waters of the state or the United States resulting from noncompliance with the limits contained in paragraph B above, including such accelerated or additional &ROQO&58 EFFLUENT LIMITATIONS CD »J3 03 Mall CD Instaurtan Pally A PalWHMrisMi Concentration t !• •ct

Parameter Ibs/day kg/day Concentration Ibs/day kg/day

Total Sespended Solids 450 205 30eg/L 676 307 45B9/L Iron

The ml shall not be lest than (.0 standard units nor greater tbasj 9.0 standard writs. The discharge shall be free from floating solids, sledge deposits, debris, oil and sew.

v t -3- monitoring as necessary to determine the nature and impact of the noncomplying discharge. F. The County shall at all times comply with the requirements of this Attachment C, except that the following modifications of these requirements shall apply for the period between the date of entry of the Consent Decree and the date when the treatment plant is complete: 1. The maximum daily average and maximum instantaneous concentration for iron (Total) shall be 5.0 mg/L and 7.5 mg/L, respectively, in lieu of the iron limits specified in paragraph B, above. 2. Monitoring for, and point of compliance with, the effluent limitations at paragraph B above shall be at the downstream outlet from Army Pond. Composite sampling shall consist of 12 grab samples collected within a 24-hour period at least two times per month. In lieu of the measurement frequencies specified in paragraph A hereof, grab samples shall be taken at least two times per month for pH and composite samples shall be taken and analyzed at least two times per month for total suspended solids and iron. Flow shall be determined by weekly estimates performed for each recovery well. 3. For this interim period, a grab sample shall be collected for each recovery well at least monthly and analyzed for iron and pH in lieu of any other parameter specific sampling listed in paragraph A hereof. To the extent practicable, the collection of samples from the recovery wells shall be coordinated with the collection of samples required pursuant to paragraph F-2. 4. At least one bioassay shall be conducted each quarter on a single sample composed of flow-proportioned grab samples collected from all of the operating recovery wells in accordance with paragraph A hereof. 5. Daily average flow of groundwater that may be discharged from all recovery wells shall not .exceed 1.8 Million Gallons per Day (MGD). The daily average flow shall be computed by summing the total flow from all operating recovery wells during a calendar quarter and then dividing by the number of days in that quarter. m X X (—H 03 *—H

AR000662 Exhibit 5

Work Plan for Scope of Work-l

Army Creek Landfill Superfund Site New Castle County Delaware

AROG0663 tc >—3 o^

ARQOQ661* Exhibit 6

Work Plan for Scope of Work-2

Army Creek Landfill Superfund Site New Castle County Delaware

AR000665 X EC 65

ARGG0666 Exhibit 7

Pre-Authorization Decision Document for Private Settlors

Army Creek Landfill Superfund Site New Castle County Delaware

AR000667 Re: Amy Creek Landfill site Ref: CERCLA 90-003

DECISION DOCUMENT PREAUTHORIZATION OF A CERCLA §111 (a) CLAIM ARMY CREEK LANDFILL SITE - NEW CASTLE COUNTY, DELAWARE

STATEMENT OF AU Section 111 of the Corprehensive Environmental Response, Compensation, and Liability Act of 1930 ("CERCLA"), 42 U.S.C. 9601 et seq., as amended by the Superfund Amendments and Reauthorization Act of 1036 ("SARA") authorizes the reimbursement of response costs incurred in carrying out the National Contingency Plan ("NCP"), 40 CFR Part 300. Section 112 of CERCLA directs the President to establish the forms and procedures for filing claims against the Hazardous Substance Superfund ("the Superfund" or "the Fund"). Executive Order 12530 delegates to the Administrator of the Environmental Protection Agency ("EPA") the responsibility for such claims. Executive Order 12580 also delegates to the EPA Administrator the authority to reach settlements pursuant to section 122(b) of CERCLA. The Director, Office of Emergency and Remedial Response ("Director, OERR") is delegated authority to evaluate 'and make determinations regarding claims (EPA Delegation 14-9, September 13, 1937, and EPA Redelegation R-14-9 "Claims Asserted Against the Fund," May 25, 1938).

BACKGROUND ON THE SITE On September 30, 1936, James M. Seif, EPA Regional Administrator for Region III, signed the first Record of Decision ("ROD-l") for the Army Creek Landfill Site (hereinafter referred to as the "Site" or "Army Creek Site"). ROD-l calls for the health and environmental threats posed by the Site to be addressed by means of installation of a surface cap, gas venting system, appropriate erosion and sediment controls, and pumping of groundwater. These activities wLth the exception of pumping_o_f groundwater are collectively referred to in the Consent Decree being executed simultaneously with this Preauthorization Decision Document (PDD) a.s "Work-1." The activities collectively referred to in the Consent Decree as "Work-1" are the subject of this PDD. On June 29, 1990, Edwin B. Erickson, EPA Regional Administrator for Region III, signed a second Record of Decision ("ROD-2") for the Army Creek Site. ROD-2 calls for the health and environmental threats posed by the Site to be addressed by means of a groundwater pumping and treatment system design to treat the groundwater underlying the Site and the adjacent Delaware Sand and Gravel Site. The activities collectively referred to as Work-2 are

AR000666 the .subject of a separate PDD, which is attached to the Consent Decree, and are not covered by this PDD. In February 1080, ETA, pursuant to section 106(a) of CERCLA, issued notice letters to a number of potentially responsible parties ("PRPs"). Discussions between EFA and the PRPs aimed at settlement of the case resulted in an agreement in principle between EPA and a nurber of the PRPs in September 1989. This agreenent provides that the Private Settlors, a nur.ber of PRPs who are proposed settlors, as defined in the Consent Decree, shall implement the remedial activities of Work-1, including operation and maintenance, at the Site in compliance with the Consent Decree. EPA agreed to reimburse the Private Settlors ten percent of necessary response costs incurred in carrying out Work-1, excluding the costs of operation and maintenance. The agreement also provided that Ncv Castle County, the remaining PRP who is a proposed settlor (hereinafter referred to as "the County"), will carry out Work-2 and that EPA vill reimburse the County forty percent of necessary response costs. As stated above, this PDD addresses only icork-l and the reimbursement of the Private Settlors. f The allocation of remedial tasks between the Private Settlors J and the County is made solely for the purpose of presenting claims ] against the Fund. Notwithstanding such allocation of remedial / tasks, the Settlors are jointly and severally liable for \_ obligations imposed by the Consent Decree.

On August 13, 1900, the Private Settlors submitted a formal Application for Preauthorization as required by section 300.700(d) of the NCP. The Scope of i-.Tork, which is appended to the Consent Decree, will be used to implement ROD-l as summarized above.

FINDINGS Preauthorization (i.e., EPA's prior approval to submit a claim against the Superfund for reasonable and necessary response costs incurred as a result of carrying out the NCP) represents the Agency's coimnitT«ent that if the response action is conducted in accordance with the preauthorization, the Consent Decree, CERCLA and the NCP, and,costs are reasonable and necessary, reimbursement, subject to any maximum amount of money set forth in the Preauthorization Decision Document, will be had from the Superfund. Preauthorization is a discretionary action by the Agency. EPA has determined, based on its evaluation of relevant documents and the Private Settlors' Application for Preauthorization, pursuant to section 300.700(d) of the NCP, that: (1) A release or potential release of hazardous substances

AROQ0669 warranting a response under section 300.435 of the NCP exists at the Army Creek Site; (2) The Private Settlors have agreed to implement the cost- effective remedy selected by EPA to address the threat posed by the release at the Site; (3) The Private Settlors have demonstrated engineering expertise and a knowledge of the NCP and attendant guidance; (4) The activities proposed by the Private Settlors, when supplemented by the terms and conditions contained herein, are consistent with the NCP; and (5) The Private Settlors have demonstrated efforts to obtain the cooperation of the State of Delaware. while EPA does not accept as fact all of the statements contained in the Private Settlor's Application for Preauthorization, the Application demonstrates a knowledge of relevant NCP provisions and EPA guidance for the conduct of a remedial action. The Consent Decree, including the terms and conditions specified in the Preauthorization Decision Document, the RODs, and the Scope of work shall govern the conduct of the remedial action. In the event of any ambiguity or inconsistency between the Application for Preauthorization and this Preauthorization Decision Document with regard to claims against the Fund, the Preauthorization Decision Document and the Consent Decree shall govern.

DECISION AND TERMS AND CONDITIONS /' I preauthorize the Private Settlors to submit a claim(s) against the Superfund for an amount not to exceed the lesser of one million nine hundred and seventy six thousand dollars ($1,976,000), or ten percent (10%) of reasonable and necessary eligible costs, unless such amount is adjusted by EPA pursuant to paragraph 14 \ below, incurred for completion of the design and construction of the remedy set forth in EPA's Record of Decision for the Army Creek Site (Exhibit 1 hereto) as specified in the Scope of Work (which is incorporated into the Consent Decree) and the Work Plans when approved by EPA ^(hereinafter referred to as Work-1), subject to the terms and conditions set forth below. In the event of any ambiguity or inconsistency between the terms and conditions and the Discussion (which follows some of the terms and conditions), the terms and conditions shall govern. 1) The Private Settlors, as provided in Section VII. (Implementation of work) of the Consent Decree, shall develop Work Plans for Work-1. Such Work Plans shall include provision for the development and implementation of a worker health and safety plan. The Health and Safety Plan shall

AR000670 - 4 -

comply with OSHA Safety and Health Standards: Hazardous Waste Operations and Emergency Response (29 CFR Part 1910.120; 54 Federal Register 9204 et sea.. March 6, 1989). Discussion: As a part of the Health and Safety Plan, the Private Settlors will develop a Spill/Volatile Emissions Contingency Plan to address the protection of area residents from the physical, chemical and/or biological hazards particular to the Site and the selected remedial action. In addition, Private Settlors shall develop an air monitoring plan for the Site during the remedial action. In accordance with the Consent Decree and Scope, of Work, Private Settlors will implement Work Plans as approved by EPA. 2) Private Settlors shall undertake Work-1 in accordance with the requirements of all "applicable" or "relevant and appropriate" Federal and State environmental laws, regulations and requirements as identified pursuant to the Consent Decree and pursuant to section 121 of CERCLA. All activities undertaken by Private Settlors off-site shall, in addition, comply with all applicable permit requirements, unless an exemption from the requirements of such permits is granted according to law. 3) Modification of remedial design elements contained in EPA's Final Design Report, the performance standards specified in Section Vi.C (Work To Be Performed) of the Consent Decree, or the Scope of Work, shall require approval by the EPA Regional Administrator or his/her designee. Such modifications, when approved in accordance with Agency procedures by the Regional Administrator, shall modify this decision document. 4) Private Settlors, pursuant to Section VI. (Work To Be Performed) of the Consent Decree, shall provide for long-term site management (i.e., operation and maintenance) of the Site sufficient to ensure the long-term effectiveness and permanence of Work-1. The costs of operation and maintenance, unlike the costs to determine that the remedy is functional (i.e., "shakedown costs"), are not eligible for reimbursement. 5) Private Settlors shall develop and implement for Work-1: a) Procedures which provide adequate public notice of solicitations for offers or bids on contracts. Solicitations must include the evaluation methods and the criteria for contractor selection. Pursuant to Section VI.A (Work To Be Performed) of the Consent Decree, Private Settlors shall notify EPA of the qualifications of any contractor or subcontractor. EPA shall have the right to disapprove the selection of the architect or engineer and

AR000671 - 3 -

the construction firm(s) selected by Private Settlors. The reasons for any such disapproval shall be communicated to Private Settlors in writing. Discussion: The Private Settlors' Application for Preauthorization states that EPA will review bid proposals and may instruct the Private Settlors to remove a particular bid proposal from consideration. while the Consent Decree provides that EPA may disapprove a contractor based on technical qualification, it is unlikely that EPA will so instruct the Private Settlors. When soliciting bids or proposals, Private Settlors shall give adequate (generally 30 days before receipt of bids or proposals) public notice in professional journals, newspapers, or publications of general circulation over a reasonable area. b) Procedures for procurement transactions which: provide maximum open and free competition; do not unduly restrict or eliminate competition; and provide for the award of contracts to the lowest, responsive, responsible bidder, when the selection can be made principally on the basis of price. Private Settlors and their contractors shall use free and open competition in the procurement of supplies, services and construction. Discussion: While Private Settlors are not required to comply with the Federal procurement requirements found at 40 CFR Part 33 or EPA's Guidance on State Procurement Under Remedial Cooperative Agreements (OSWER Directive 9375.1- 11, June 1983), they should be guided by these documents in the development of procurement procedures for small purchases, formal advertising, competitive negotiations and noncompetitive negotiations as each may be appropriate to remedying the release or threat of release at the Site. Small purchase procedures are those relatively simple, informal procurement methods for securing services, supplies and other property from an adequate number of qualified sources when the services, supplies and other property being purchased constitute a discrete procurement transaction and do not cost more than $25,000 in the aggregate. Private Settlors shall not divide procurement transactions into smaller parts to avoid the dollar limitation. The award of any fixed price contract by Private Settlors satisfies the requirement of open and free competition for any subcontracts awarded within the scope of the prime contract.

RR000672 - 6 -

c) A prequalified list(s) of persons, firms, or products for use in acquiring goods and services, if appropriate. Such list(s) must be current and include enough qualified sources to ensure maximum open and free competition. Private Settlors should not preclude potential offerors who are not on the prequalified list from qualifying during the solicitation period. d) Fixed-price contracts for construction which include a Differing Site Conditions clause equivalent to that found at 40 CFR §33.1030(4) (1937). Discussion: The Private Settlors' Application for Preauthorization states that contracts will include a differing sites conditions that "generally is in accord" with the above stated requirement. The Private Settlors shall include in all fixed-price contracts for construction a provision eg"jvalent to that found at 40 CFR §33.1030(4) (1987) . e) Procedures to settle and satisfactorily resolve, in accordance with sound business judgment and good administrative practice, all contractual and administrative issues arising out of preauthorized actions. Private Settlors shall issue invitations for bids or requests for proposals; select contractors; approve subcontractors; manage contracts in a manner to minimize change orders and contractor claims; resolve protests, claims, and other procurement related disputes; and handle subcontracts to assure that work is performed in accordance with terms, conditions and specifications of contracts. f) A change order management policy and procedure generally in accordance with EPA's guidance on State Procurement Under Remedial Cooperative Agreements (OSWER Directive 9375.1-11, June 1988) . g) Detailed data quality assurance/quality control plans for sample collection and analysis activities (e.g., sampling, treatability studies, monitoring) in accordance with Section.XII. (Data Quality Assurance) of the Consent Decree. h) A financial management system that consistently applies generally accepted accounting principles and practices and includes an accurate, current and complete accounting of all financial transactions for the project, complete with supporting documents, and a systematic method to resolve audit findings and recommendations.

AROG0673 - 7 -

6), Pursuant to Section XI. (Designated Remedial Project Manager and Project Coordinators) of the Consent Decree, Private Settlors shall notify EPA of their selection of the Project Coordinator who shall be responsible for overseeing and administering the cleanup. As a term and condition of preauthorization, EPA shall have the right to disapprove the Project Coordinator selected by Private Settlors. The reason(s) for any such disapproval shall be communicated to Private Settlors in writing. In addition, the Private Settlors shall, as soon as practicable following the date of entry of the Consent Decree, supply EPA with a Management Plan including an organization and function chart identifying the responsibilities of and relationship between individuals responsible for the management of Work-1 (e.g., Private Settlors' Committee, Project Coordinator, Trustee, Construction Manager, Independent Quality Assurance Team, Contractors, Subcontractors). Discussion: The Private Settlors' Application for Preauthorization did not contain a detailed Management Plan for the response action. As a term and condition of preauthorization, the Private Settlors shall satisfy the above requirement. The Management Plan shall be submitted to EPA concurrent with the Work Plan under the schedule specified in Section VII. (Implementation Of Work) of the Consent Decree. 7) In order to provide for construction management for the Site, Private Settlors may utilize the competitive negotiation procurement method for award of the contract for architectural and engineering ("A&E") services. Private Settlors may award a cost reimbursement contract for A&E services and that contract may include an upper limit on costs. Discussion: Other professional services which do not constitute construction may also be procured utilizing the small purchase procurement, competitive negotiation, or noncompetitive procurement methods. 8) In order to implement construction of Work-1 at the Site, Private Settlors shall utilize the formal advertising (sealed bidding) method of procurement and shall award a fixed price contract (i.e., unit price, lump sum, or combination of lump sum and unit price) to the lowest responsive, responsible bidder for construction. The prior approval of the Regional Administrator or his/her designee is required in order for Private Settlors to use a procurement method other than the formal advertising method.

AROQ0671* Discussion: Private Settlors' Application for Preauthorization did not clearly propose the type of contract to be used for construction management or independent quality assurance. In addition, it is unclear whether individual contracts will be awarded by the Private Settlors' Committee, the Trustee or the construction management firm. EPA concludes, based on its procedures to ensure reasonable costs and the spirit of the procurement principles, that a cost reimbursement is the appropriate form of contract for A&E services and that a fixed-price contract(s) is most appropriate for construction. If Private Settlors elect to award a prime contract for A&E and construction, price competition shall occur at the subcontractor level. 9) Private Settlors shall provide EPA and its employees, contractors and agents with Site access as set forth in Section XIII. (Site Access) of the Consent Decree and shall immediately notify the Agency if they are unable to initiate or complete the preauthorized remedial action. 10) In submitting claims to the Superfund, Private Settlors shall: a) Document that response activities were preauthorized by EPA; b) Substantiate all claimed costs through a financial management system as described in paragraph 5(h); and c) Document that all claimed costs were eligible for reimbursement pursuant to this preauthorization and are reasonable and necessary in accordance with the appropriate Federal cost principles. Discussion: See paragraph 16 for additional references to the Federal cost principles. 11) Private Settlors shall maintain all cost documentation and any records relating to their claim for a period of not less than ten years from the date on which the final claim has been submitted to the Superfund, and shall provide EPA with access to their records. At the end of the ten-year period, Private Settlors shall notify EPA of the location of all records. Private Settlors shall allow EPA the opportunity to take possession of the records before they are destroyed. This requirement is in addition to the record preservation requirement located at Section XV. (Record Preservation) of the Consent Decree.

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12) Claims may be submitted against the Superfund by Private Settlors only while they are in compliance with the terms of the Consent Decree and no more frequently than intervals of: a) Project start-up through completion of clearing and brushing of Lobe 1; b) Completion of foundation fill placement for Lobe 1; c) Completion of cap construction for Lobe 1; d) Completion of foundation fill placement for Lobe 2; e) Completion of cap construction for Lobe 2; f) Completion of Site vegetation, fence construction, demobilzation and closeout; and g) Remaining eligible costs following EPA issuance of the Certificate of Completion for the construction phase of Work- 1. Discussion: Claims submitted by the Private Settlors may include the costs incurred for A&E or other professional services rendered prior to.the completion of each milestone in the above schedule. The Private Settlors may not submit claims more frequently than at six month intervals, nor, with the exception of the final claim, for amounts less than $250,000. 13) Payment of a claim for work completed does not constitute acceptance of the work performed. EPA will determine the acceptability of work performed in accordance with the Consent Decree. 14) Pursuant to Section XXII. (Claims Against The Fund And Payment of Response Costs) of the Consent Decree, if Private Settlors find it necessary to seek to modify the actions that EPA preauthorized, or if it becomes apparent that the project's costs will exceed the approved costs as set out herein, or if the Private. Settlors undertake additional work approved by EPA pursuant to the provisions of the Consent Decree, Private Settlors may submit to EPA a revised Application for Preauthorization. EPA will consider such an Application for Preauthorization and will, if appropriate, subject to the availability of appropriated funds, amend the maximum dollar amount for which Private Settlors may submit claims to the Fund. The maximum amount for which Private Settlors may submit claims will be determined according to the criteria used in approving Private Settlors' Application for Preauthorization.

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15) Claims shall be sufc-itted to the Director, Office of Emergency and Remedial Response, EPA, Washington, D.C. 20460. EPA shall provide the appropriate form(s) for such claims. 15) Prior to the payment of any claim, EPA may adjust claims using the facilities and services of private insurance and claims adjusting organizations or Federal personnel. In making a determination whether costs are allowable, the claims adjuster will rely upon the appropriate Federal cost principles (non- profit organizations - OMB Circular A-122; States and political subdivisions - OMB Circular A-37; profit making organizations - 43 CFR Subparts 31.1 and 31-2). When additional costs are incurred due to acts or omissions by the Private Settlors, payment of the claim will be adjusted accordingly. EPA may require Private Settlors to submit any additional information needed to determine whether the actions taken were reasonable and necessary. 17) At least 60 days before filing a claim against the Fund for Work-1, Private Settlors shall present in writing all claims to any person known to them who may be liable under section 107 of CERCLA for response costs incurred in carrying out the Consent Decree. If the first claim was denied by the responsible party or not responded to, and EPA agrees that there is no reason to believe that subsequent claims would be honored by such a responsible party, the denial of the first claim, or lack of response, shall be considered denial of every subsequent claim. 18) Payment of any claim shall be subject to the Private Settlors subrogating to the United States the rights of the Private Settlors to the extent to which their response costs are compensated from the Superfund. Further, Private Settlors and their contractors shall assist in any cost recovery action which may be initiated by the United States by furnishing personnel, services, documents, and materials needed to assist EPA in the collection of evidence to document work performed and costs expended by Private Settlors or Private Settlors' contractors at the Site; providing all requested assistance in the interpretation of evidence and costs and providing requested testimony. All of Private Settlors' contracts that implement preauthorized activities shall include a specific requirement that their contractors agree to provide this cost recovery assistance. 19) Pursuant to section lll(a)(2) of CERCLA, eligible costs are those costs incurred, consistent with the NCP, in carrying out the Work-1, subject to the following limitations: a) Costs may be reimbursed only if incurred after the date of this preauthorization;

AROG0677 1 -

b) Costs may be reimbursed only for completion of the design and construction of the remedy, including costs to determine that the remedy is functional, for the Site as provided herein. Such costs shall not include any of the oversight costs incurred by EPA, nor costs that were incurred by EPA prior to the effective date of the Consent Decree. c) Costs incurred for long-term operation and maintenance, as described in paragraph 4, are not eligible for reimbursement from the Superfund. d) Costs incurred for the payment of a person who is included in the List of Parties Excluded From Federal Procurement or Non-Procurement, established pursuant to Executive Order 12549, May 26, 1938, at the time the contract is awarded shall not be eligible for reimbursement, unless Private Settlors obtain approval from EPA, pursuant to 40 CFR Part 32, prior to incurring the obligation. e) Costs incurred for the payment of contractor claims either through settlement of such claims or an award by a third party may be reimbursed from the Fund to the extent EPA determines that: (i) the contractor claim arose from work within the scope of the contract at issue and the contract was for activities which were preauthorized; (ii) the contractor claim is meritorious; (iii) the contractor claim was not caused by the mis- management of Private Settlors; (iv) the contractor claim was not caused by Private Settlors' vicarious liability for the improper actions of others; (v) the claimed amount is reasonable and necessary; (vi) the claim for such costs is filed by Private Settlors within 5 years of completion of the . preauthorized activities; and (vii) " payment of such a claim will not result in total payments from the Fund in excess of the amount preauthorized. Discussion: "Contractor claim" means the disputed portion of a written demand or written assertion by any contractor who has contracted with Private Settlors pursuant to the Consent

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Decree to perform .Work-1, seeking as a matter of right, the payment of money, adjustment, or interpretation of contract terms, or other relief, arising under or related to a contract, which has been finally rejected or not acted upon by Private Settlors, or an award by a Third Party through the Disputes Clause of the contract document. f) An award by a third party on a contractor claim should include: (i) findings of fact; (ii) conclusions of law; (iii) allocation of responsibility for each issue; (iv) basis for the amount of award; and (v) the rationale for the decision. g) Interest accrues on amounts due Private Settlors pursuant to this agreement where EPA fails to pay the amount within sixty (60) days of EPA's receipt of a completed claim from Private Settlors.. A completed claim is a demand for a sum certain which includes all documentation required by EPA to substantiate the appropriateness of the amounts claimed. Where Private Settlors submit a claim which is technically complete but for which EPA requires additional information in order to evaluate the amount claimed, interest will not accrue on the claim until sixty (60) days after EPA's receipt of the requested additional information. The rate of interest paid on a claim is the rate of interest on investments of the Superfund established by subchapter A of chapter 98 of the Internal Revenue Code of 1954. 20) This Preauthorization Decision Document is intended to benefit only the Private Settlors and EPA. It extends no benefit to nor creates any right in any third party. 21) If any material statement or representation made in the Application for Preauthorization is false, misleading, misrepresented, or misstated, and EPA relied upon such statement in making its decision, the preauthorization by EPA may be withdrawn following written notice to Private Settlors. Disputes arising out of EPA's determination to withdraw its preauthorization shall be governed by Section XVIII. (Dispute Resolution) of the Consent Decree. Criminal and other penalties may apply (see Exhibit 3). 22) The Superfund is not hereby obligated to reimburse Private Settlors for subsequent remedial actions not covered by this preauthorization caused by failure of the original remedy, if those actions are necessary as a result of the failure of

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Private Settlors, their employees or agents, or any third party having a contractual relationship with Private Settlors to properly perform activities under the Consent Decree and Scope of Work and any modification thereto approved by EPA and in conformance with the terms and conditions of this Preauthorization Decision Document. The foregoing shall not apply if the remedy fails for any other reason. EPA may require Private Settlors to submit any additional information needed to determine whether the actions taken were in conformance with the Consent Decree and the Scope of Work, and were reasonable and necessary. 23) This preauthorization shall be effective as of the date of execution. Reimbursement from the Fund shall be contingent upon: (1) EPA's approval in writing of the performance of specific response activities to be initiated prior to the date of entry of the Consent Decree, and (2) entry of the Consent Decree by the Court,

Henry L./LongesII Dat£ Emergency & Remedial Response

EXHIBITS 1. EPA Records of Decision for the Army Creek Landfill Site 2. Consent Decree 3. Civil and Criminal Penalties

ARGG068G EXHIBIT 3

CERCLA PENALTY FOR PRESENTING FRAUDULENT CLAIM Any person who knowingly gives or causes to be given false information as a part of a claim against the Hazardous Substance Superfund may, upon conviction, be fined in accordance with the applicable provisions of title 18 of the United States Code or imprisoned for not more than 3 years (or not more than 5 years in the case of a second of subsequent conviction), or both. (42 USC 9612(b)(1).)

CIVIL PENALTY FOR PRESENTING FRAUDULENT CLAIM The claimant is liable to the United States for a civil penalty of $2,000, and in an amount equal to two times the amount of damages sustained by the Government because of the acts of that person, and costs of the civil action. (31 USC 3729 and 3730.)

CRIMINAL PENALTY FOR PRESENTING FRAUDULENT CLAIM OR MAKING FALSE STATEMENTS

The claimant will be charged a maximum fine of not more than $10,000 or be imprisoned for a maximum of 5 years, or both. (See 62 Stat. 698, 749; 18 USC 287, 1001.)

AROG0681 Xffi 5 3 00

ARGG0682 Exhibit 8

Pre-Authorization Decision Document for New Castle County

Army Creek Landfill Superfund Site New Castle County Delaware

AROG0683 Re: Army Creek Landfill site Ref: CERCLA 90-002

DECISION DOCUMENT PREAUTHORIZATION OF A CERCLA §111(a) CLAIM ARMY CREEK LANDFILL SITE - NEW CASTLE COUNTY, DELAWARE

STATEMENT OF AUTHORITY Section 111 of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 ("CERCLA"), 42 U.S.C. 9601 et sag., as amended by the Superfund Amendments and Reauthorization Act of 1986 ("SARA") authorizes the reimbursement of response costs incurred in carrying out the National Contingency Plan ("NCP"), 40 CFR Part 300. Section 112 of CERCLA directs the President to establish the forms and procedures for filing claims against the Hazardous Substance Superfund ("the Superfund" or "the Fund"). Executive Order 12580 delegates to the Administrator of the Environmental Protection Agency ("EPA") the responsibility for such claims. Executive Order 12580 also delegates to the EPA Administrator the authority to reach settlements pursuant to section 122(b) of CERCLA; The Director, Office of Emergency and Remedial Response ("Director, OERR") is delegated authority to evaluate and make determinations regarding claims (EPA Delegation 14-9, September 13, 1987, and EPA Redelegation R-14-9 "Claims Asserted Against the Fund," May 25, 1988). BACKGROUND ON THE SITE On September 30, 1986, James M. Self, EPA Regional Administrator for Region III, signed the first Record of Decision ("ROD-l") for the Army Creek Landfill Site (hereinafter referred to as the "Site" or "Army Creek Site"). ROD-l calls for the health and environmental threats posed by the Site to be addressed by means of installation of a surface cap, gae venting system, appropriate eroeion and sediment controls, and pumping of groundwater. These activities with the exception of pumping of groundwater are collectively referred to in the Consent Decree being executed simultaneously with this Preauthorization Decision Document (POD) ae "Work -1." The activities collectively referred to as Work-1 are the subject of a separate PDD, which is attached to the Consent Decree, and are not covered by this PDD. On June 29, 1990, Edwin B. Erickson, EPA Regional Administrator for Region III, signed a second Record of Decision ("ROD-2") for the Army Creek Site. ROD-2 calls for the health and environmental threats posed by the site to be addressed by means of a groundwater pumping and treatment system design to treat the groundwater underlying the Site and the adjacent Delaware Sand and Gravel Site. The activities collectively referred to in the Consent Decree ae "Work-2" are the subject of this PDD. - 2 -

In February 1989, EPA, pursuant to section 106(a) of CERCLA, issued notice letters to a number of potentially responsible parties ("PRPs"). Discussions between EPA and the PRPs aimed at settlement of the case resulted in an agreement in principle between EPA and a number of the PRPs in September 1989. This agreement provides that New Castle County, one of the PRPs who is a proposed settlor (hereinafter referred to as "the County"), shall implement the remedial activities of Work-2 at the Site in compliance with the Consent Decree. EPA agreed to reimburse the County forty percent of necessary response costs it incurs in carrying out Work-2. The agreement also provided that EPA will reimburse the Private Settlors, the remaining PRPs who are proposed settlors, ten percent of necessary response costs incurred in carrying out Work-1 excluding the costs of operation and maintenance. As stated above, this PDD addresses only Work-2 and the reimbursement of the County. The allocation of remedial tasks between the County and the Private Settlors is made solely for the purpose of presenting claims against the Fund. Notwithstanding such allocation of remedial tasks, the Settlors are jointly and severally 'liable for obligations imposed by the Consent Decree. On February 14, 1990, the County submitted a formal Application for Preauthorization as required by section 300.700(d) of the NCP. The Scope of Work, which is appended to the Consent Decree, will be used to implement Work-2 as summarized above. FINDINGS Preauthorization (i.e., EPA's prior approval to submit a claim against the Superfund for reasonable and necessary response costs incurred as a reeult of carrying out the NCP) represents the Agency's commitment that if the response action is conducted in accordance with the preauthorization, the Consent Decree, CERCLA and the NCP, and coets are reasonable and necessary, reimbursement, subject to any maximum amount of money set forth in the Preauthorization Decision Document, will be had from the Superfund. Preauthorization is a discretionary action by the Agency. EPA hae determined, based on its evaluation of relevant documents and the County's Application for Preauthorization, pursuant to section 300.700(d) of the NCP, that: (1) A release or potential release of hazardous substances warranting a response under section 300.435 of the NCP exists at the Army Creek Site; (2) The County agreed to implement the cost-effective remedy

AROG0685 - 3 -

selected by EPA to address the threat posed by the release at the Site; (3) The County has demonstrated engineering expertise and a knowledge of the NCP and attendant guidance; (4) The activities proposed by the County, when supplemented by the terms and conditions contained herein, are consistent with the NCP; and (5) The County has demonstrated its efforts to obtain the cooperation of the State of Delaware. While EPA does not accept as fact all of the statements contained in the County's Application for Preauthorization, the Application demonstrates a knowledge of relevant NCP provisions and EPA guidance for the conduct of a remedial action. The Consent Decree, including the terms and conditions specified in the Preauthorization Decision Document, the RODs, and the Scope of Work shall govern the conduct of the remedial action. In the event of any ambiguity or inconsistency between the Application for Preauthorization and this Preauthorization Decision Document with regard to claims against the Fund, the Preauthorization Decision Document and the Consent Decree shall govern. DECISION AND TERMS AND CONDITIONS I preauthorize New Castle County to submit a claim(s) against the Superfund for an amount not to exceed the lesser of two million dollars ($2,000,000), or forty percent (40%) of reasonable and necessary eligible costs, unless such amount is adjusted by EPA pursuant to paragraph 14 below, incurred, for completion of the design and the construction and operation of the remedy set forth in EPA's Record of Decision for the Army Creek Site (Exhibit l hereto) as specified in the Scope of Work (which is incorporated into the Consent Decree) and the Work Plans when approved by EPA (hereinafter referred to as Work-2), subject to the terms and conditions set forth below. The costs for operation of the groundwater recovery and treatment system shall be eligible for a period not to exceed ten years from the commencement of operations of the treatment facility or such lesser period of time when EPA determines, consistent with ROD-l, that operation of the system by the County is no longer required. In the event of any ambiguity or inconsistency between the terms and conditions and the Discussion (which follows some of the terms and conditions), the terms and conditions shall govern. 1) The County, as provided in Section VII. (Implementation of Work) of the Consent Decree, shall develop Work Plans for Work-2. Such Work Plans shall include provision for the development and implementation of a worker health and safety plan. The Health and Safety Plan shall comply with OSHA Safety and Health Standards: Hazardous Waste Operations and

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1 Emergency Response (29 CFR Part 1910.120; 54 Federaj. Register 9294 et sag.. March 6, 1989).

Discussion: As a part of the Health and Safety Plan, the County will develop a Spill/Volatile Emissions Contingency Plan to address the protection of area residents from the physical, chemical and/or biological hazards particular to the site and the selected remedial action. In addition, the County shall develop an air monitoring plan for the Site during the remedial action. In accordance with the Consent Decree and Scope of Work, the County will implement Work Plans as approved by EPA. 2) The County shall undertake Work-2 in accordance with the requirements of all "applicable" or "relevant and appropriate" Federal and State environmental laws, regulations and requirements as identified pursuant to the Consent Decree and pursuant to section 121 of CERCLA. All activities undertaken by the County off-site shall, in addition, comply with all applicable permit requirements, unless an exemption- from the requirements of such permits is granted according to law. 3) Modification of remedial design elements contained in the Final Design to be approved by EPA, the performance standards specified in Section VI.c (Work To Be Performed) of the Consent Decree, or the Scope of Work shall require approval by the EPA Regional Administrator or his/her designee. Such modifications, when approved in accordance with Agency procedures by the Regional Administrator, shall modify this decision document. 4) The County, pursuant to Section VI. (Work To Be Performed) of the Consent Decree, shall provide for long-term site management (i.e., operation and maintenance) of the Site sufficient to ensure the long-term effectiveness and permanence of Work-2. The costs of operation and maintenance, unlike the costs to determine that the remedy is functional (i.e., "shakedown costs"), are not eligible for reimbursement. Discussion: Costs associated with pumping and treatment of groundwater are a part of Work-2 and are eligible for reimbursement from the Fund for up to ten years from the commencement of operation of the treatment facility or such lesser period of time when EPA determines, consistent with ROD-l, that operation of the system by the County is no longer

ARGG0687 - 5 -

required, and shall not be considered operation and maintenance costs. 5) The County shall develop and implement for Work-2: a) Procedures which provide adequate public notice of solicitations for offers or bids on contracts. Solicitations must include the evaluation methods and the criteria for contractor selection. Pursuant to Section VI. (Work to Be Performed) of the Consent Decree, the County shall notify EPA of the qualifications of any contractor or subcontractor. EPA shall have the right to disapprove the selection of the architect or engineer and the construction firm(s) selected by the County. The reasons for any such disapproval shall be communicated to the County in writing. Discussion: When soliciting bids or proposals, the County shall give adequate (generally 30 days before receipt of bids or proposals) public notice in professional journals, newspapers, or publications of general circulation over a reasonable area. b) Procedures for procurement transactions which: provide maximum open and free competition; do not unduly restrict or eliminate competition; and provide for the award of contracts to the lowest, responsive, responsible bidder, when the selection can be made principally on the basis of price. The County and its contractors shall use free and open competition in the procurement of supplies, services and construction. Discussion: While the County is not required to comply with the Federal procurement requirements found at 40 CFR Part 33 or EPA's Guidance on State Procurement Under Remedial Cooperative Agreements (OSWER Directive 9375.1-11, June 1988), it should be guided by these documents in the development of procurement procedures for small purchases, formal advertising, competitive negotiations and noncompetitive negotiations as each may be appropriate to remedying the release or threat of release at the Site. Small purchase procedures are those relatively simple, informal procurement methods for securing services, supplies and other property from an adequate number of qualified sources when the services, supplies and other property being purchased constitute a discrete procurement transaction and do not cost more than $25,000 in the aggregate. The County shall not divide procurement transactions into smaller

&ROG0688 - 6 -

parts to avoid the dollar limitation. The award of any fixed price contract by the County satisfies the requirement of open and free competition for any subcontracts awarded within the scope of the prime contract. c) A prequalified list(s) of persons, firms, or products for use in acquiring goods and services, if appropriate. Such list(s) must be current and include enough qualified sources to ensure maximum open and free competition. The County should not preclude potential offerers who are not on the prequalified list from qualifying during the solicitation period. d) Fixed-price contracts for construction which include a Differing Site Conditions clause equivalent to that found at 40 CFR §33.1030(4) (1987). e) Procedures to settle and satisfactorily resolve, in accordance with sound business judgment and good administrative practice, all contractual and administrative issues arising out of preauthorized actions. The County shall issue invitations for bids or requests for proposals; select contractors; approve subcontractors; manage contracts in a manner to minimize change orders and contractor claims; resolve protests, claims, and other procurement related disputes; and handle subcontracts to assure that work is performed in accordance with terms, conditions and specifications of contracts. f) A change order management policy and procedure generally in accordance with EPA's guidance on State Procurement Under Remedial Cooperative Agreements "(OSWER Directive 9375.1-11, June 1988). g) Detailed data quality assurance/quality control plans for sample collection and analysis activities (e.g., sampling, treatability studies, monitoring) in accordance with Section XII. (Data Quality Assurance) of the Consent Decree. h) A financial management system that consistently applies generally accepted accounting principles and practices and includes an accurate, current and complete accounting of all financial transactions for the project, complete with supporting documents, and a systematic method to resolve audit findings and recommendations. 6) Pursuant to Section XI. (Designated Remedial Project Manager And Project Coordinators) of the Consent Decree, the County shall notify EPA of its selection of the Remedial Project Coordinator who shall be responsible for overseeing and administering the cleanup. As a tern and condition of

AR000689 - 7 -

• preauthorization, EPA shall have the right to disapprove the Remedial Project Coordinator selected by the County. The reason(s) for any such disapproval shall be communicated to the County in writing. 7) Costs incurred by the County, after the effective date of preauthorization by EPA, pursuant to the contract it previously awarded for design work during construction are eligible for reimbursement subject to the terms and conditions specified herein, and are subject to the County's cost- reimbursement contract with the firm for architectural and engineering ("A&E") services. In the event that the County elects to contract for construction management services for the Site, the County may utilize the competitive negotiation procurement method for award of the contract to a construction management firm. The County may award a cost reimbursement contract for the construction management services and that contract may include an upper limit on costs. Discussion: The County's Application for Preauthorization d'id not specify the method of procurement, nor the type of contract it awarded for A&E services during construction. The term and condition above clarifies EPA's understanding of the method and type of contract and specifies the requirements to be satisfied for such costs to be eligible for reimbursement. In addition, the Application does not state whether the County plans to utilize the services of a construction manager. The term and condition above specifies the requirements to be satisfied for such costs in order to be eligible for reimbursement. 8) In order to implement construction of Work-2 at the Site, the County shall utilize the formal advertising (sealed bidding) method of procurement and shall award a fixed price contract (i.e., unit price, lump sum, or combination of lump sum and unit price) to the lowest responsive, responsible bidder for construction. The prior approval of the Regional Administrator or his/her designee is required in order for the County to use a procurement method other than the formal advertising method. 9) The County shall provide EPA and its employees, contractors and agente with Site access as set forth in Section XIII. (Site Access) of the Consent Decree and shall immediately notify the Agency if it is unable to initiate or complete the preauthorized remedial action. 10) In submitting claims to the Superfund, the County shall: a) Document that response activities were preauthorized by EPA;

AR000690 - 8 -

b) Substantiate all claimed costs through a financial management system as described in paragraph 5(h); and c) Document that all claimed costs were eligible for reimbursement pursuant to this preauthorization and are reasonable and necessary in accordance with the appropriate Federal cost principles. Discussion: See paragraph 16 for additional references to the Federal cost principles. 11) The County shall maintain all cost documentation and any records relating to its claim for a period of not less than ten years from the date on which the final claim has been submitted to the Superfund, and shall provide EPA with access to its records. At the end of the ten-year period, the County shall notify EPA of the location of all records. The County shall allow EPA the opportunity to take possession of the records before they are destroyed. This requirement is in addition to the record preservation requirement located at Section XV. (Record Preservation) of the Consent Decree. 12) Claims may be submitted against the Superfund by the County only while it is in compliance with the terms of the Consent Decree and no more frequently than intervals of: a) Completion of construction of the treatment facility; b) Annually thereafter for up to ten years for the cost of operating the pumping and treatment system; and c) Remaining eligible costs following EPA issuance of the Certification of Completion or ten (10) years from the date of initiation of pumping and treatment. 13) Payment of a claim for work completed does not constitute acceptance of the work performed. EPA will determine the acceptability of work performed in accordance with the Consent Decree. 14) Pursuant to Section XXII. (Claims Against The Fund And Payment Of Response Costs) of the Consent Decree, if the County finds it necessary to seek to modify the actione that EPA preauthorized, or if it becomes apparent that the project's costs will exceed the approved coets as set out herein, or if the County undertakes additional work approved by EPA pursuant to the provisions of the Consent Decree, the County may submit to EPA a revised Application for Preauthorization. EPA will consider such an Application for Preauthorization and will, if appropriate, subject to the availability of

AR00069I - 9 -

' appropriated funds, amend the maximum dollar amount for which the County may submit claims to the Fund. The maximum amount for which the County may submit claims will be determined according to the criteria used in approving the County's Application for Preauthorization. 15) Claims shall be submitted to the Director, Office of Emergency and Remedial Response, EPA, Washington, D.C. 20460. EPA shall provide the appropriate form(s) for such claims. 16) Prior to the payment of any claim, EPA may adjust claims using the facilities and services of private insurance and claims adjusting organizations or Federal personnel. In making a determination whether costs are allowable, the claims adjuster will rely upon the appropriate Federal cost principles (non- profit organizations - OMB Circular A-122; States and political subdivisions - OMB circular A-87; profit making organizations - 48 CFR Subparts 31.1 and 31-2). Where additional costs are incurred due to acts or omissions by the County, payment of the claim will be adjusted accordingly. EPA may require the County to submit any additional information needed to determine whether the actions taken were reasonable and necessary. 17) At least 60 days before filing a claim against the Fund for Work-2, the County shall present in writing all claims to any person known to them who may be liable under section 107 of CERCLA for response costs incurred in carrying out the Consent Decree. If the first claim was denied by the responsible party or not responded to, and EPA agrees that there is no reason to believe that subsequent claims would be honored by such a responsible party, the denial of the first claim, or lack of response, shall be considered 'denial of every subsequent claim. 18) Payment of any claim shall be subject to the County subrogating to the United States the rights of the County to the extent to which its response costs are compensated from the Superfund. Further, the County and its contractors shall assist: in any cost recovery action which may be initiated by the United States by furnishing personnel, services, documents, and materials needed to assist EPA in the collection of evidence to document work performed and costs expended by the County or the County's contractors at the Site; providing all requested assistance in the interpretation of evidence and coete and providing requested testimony. All of the County's contracts that implement preauthorized activitiee shall include a specific requirement that the contractore agree to provide this cost recovery assistance. 19) Pursuant to section lll(a)(2) of CERCLA, eligible costs are those costs incurred, consistent with the NCP, in carrying out the Work-2, subject to the following limitations:

AR000692 - 10 - a) Costs may be reimbursed only if incurred after the date of this preauthorization; b) Costs may be reimbursed only for completion of the design and construction of the remedy, including costs to determine that the remedy is functional, and pumping and treatment of groundwater at the Site as provided herein. Such costs shall not include any of the oversight costs incurred by EPA, nor costs that were incurred by EPA prior to the effective date of the Consent Decree. c) Costs incurred for long-term operation and maintenance, as described in paragraph 4, are not eligible for reimbursement from the Superfund. Discussion: Costs associated with pumping and treatment of groundwater are a part of Work-2 and are not operation and maintenance costs. The costs of pumping and treatment of groundwater are eligible for reimbursement from the Fund for up to ten years or such lesser period of time when EPA determines, consistent with ROD-l, that operation of the system by the County is no longer required. d) Costs incurred for the payment of a person who is included in the List of Parties Excluded From Federal Procurement or Non-Procurement, established pursuant to Executive Order 12549, May 26, 1988, at the time the contract is awarded shall not be eligible for reimbursement unless the County obtains approval from EPA, pursuant to 40 CFR Part 32, prior to incurring the obligation. e) Costs incurred for the payment of contractor claims either through settlement of such claims or an award by a third party may be reimbursed from the Fund to the extent EPA determines that: (i) the contractor claim arose from work within the scope of the contract at issue and the contract wae for activities which were preauthorized; (ii) the contractor claim is meritorious; (iii) the contractor claim was not caused by the mis- management of the County; (iv) the contractor claim was not caused by the County's vicarious liability for the improper actione of others;

AR000693 - 11 -

(v) the claimed amount is reasonable and necessary; (vi) the claim for such costs is filed by the County within 5 years of completion of the preauthorized activities; and (vii) payment of such a claim will not result in total payments from the Fund in excess of the amount preauthorized. Discussion: "Contractor claim" means the disputed portion of a written demand or written assertion by any contractor who has contracted with the County pursuant to the Consent Decree to perform Work-2, seeking as a matter of right, the payment of money, adjustment, or interpretation of contract terms, or other relief, arising under or related to a contract, which has been finally rejected or not acted upon by the County, or an award by a Third Party through the Disputes Clause of the contract document. f) An award by a third party on a contractor claim should include: (i) findings of fact; (ii) conclusions of law; (iii) allocation of responsibility for each issue; (iv) basis for the amount ot award; and (v) the rationale for the decision. g) Intereet accrues on amounts due the County pursuant to this agreement where EPA fails to pay the amount within sixty (60) days of EPA's receipt of a completed claim from the County. A completed claim is a demand for a sum certain which includee all documentation required by EPA to substantiate the appropriateness of the amounts claimed. Where the County submits a claim which is technically complete but for which EPA requires additional information in order to evaluate the amount claimed, interest will not accrue on the claim until sixty (60) days after EPA's receipt of the requested additional information. The rate of intereet paid on a claim ie the rate of intereet on investments of the Superfund established by subchapter A of chapter 98 of the Internal Revenue Code of 1954. 20) Thie Preauthorization Decision Document is intended to benefit only the County and EPA. It extends no benefit to nor creates any right in any third party.

AR000691* - 12 -

21) If any material statement or representation made in the Application for Preauthorization is false, misleading, misrepresented, or misstated and EPA relied upon such statement in making its decision, the preauthorization by EPA may be withdrawn following written notice to the County. Disputes arising out of EPA's determination to withdraw its preauthorization shall be governed by Section XVIII. (Dispute Resolution) of the Consent Decree. Criminal and other penalties may apply (see Exhibit 3). 22) The Superfund is not hereby obligated to reimburse the County for subsequent remedial actions not covered by this preauthorization caused by failure of the original remedy, if those actions are necessary as a result of the failure of the County, its employees or agents, or any third party having a contractual relationship with the County to properly perform activities under the Consent Decree and Scope of Work and any modification thereto approved by EPA and in conformance with the terms and conditions of this Preauthorization Decision Document. The foregoing shall not apply if the remedy fails for any other reason. EPA may require the County-to submit any additional information needed to determine whether the actions taken were in conformance with the Consent Decree and the Scope of Work, and were reasonable and necessary. 23) This preauthorization shall be effective as of the date of execution. Reimbursement from the Fund shall be contingent upon: (1) EPA's approval in writing of the performance of specific response activities to be initiated prior to the date of entry of the Consent Decree, and (2) entry of the Consent Decree by the Court.

Henry L/Longest II Dat Director, Offifce of Emergency & Remedial Response

EXHIBITS 1. EPA Records of Decision for the Army Creek Landfill Site 2. Consent Decree 3. Civil and Criminal Penaltiee

AR000695 EXHIBIT 3

CERCLA PENALTY FOR PRESENTING FRAUDULENT CLAIM Any person who knowingly gives or causes to be given false information as a part of a claim against the Hazardous Substance Superfund may, upon conviction, be fined in accordance with the applicable provisions of title 18 of the United States Code or imprisoned for not more than 3 years (or not more than 5 years in the case of a second of subsequent conviction), or both. (42 USC 9612(b)(1).)

CIVIL PENALTY FOR PRESENTING FRAUDULENT CLAIM The claimant is liable to the United States for a civil penalty of $2,000, and in an amount equal to two times the amount of damages sustained by the Government because of the acts of that person, and costs of the civil action. (31 USC 3729 and 3730.)

CRIMINAL PENALTY FOR PRESENTING FRAUDULENT CLAIM OR MAKING FALSE STATEMENTS The claimant will be charged a maximum fine of not more than $10,000 or be imprisoned for a maximum of 5 years, or both. (See 62 Stat. 698, 749; 18 USC 287, 1001.)

AR000696 co H SO

AR000697 Consent Decree Exhibit 9

Cost Summary Report

Army Creek Landfill Superfund Site New Castle County Delaware

AR000698 COST SUMMARY REPORT TOTAL SITE EXPENDITURES THROUGH 8/9/90 ARMY CREEK SITE, DELAWARE Site 134

Prepared by Leslie Vassallo August 21, 1990

EPA EXPENDITURES;

EPA REGION III PAYROLL $162,397.68 EPA HEADQUARTERS PAYROLL 9.979.00 $172,376.68

INDIRECT COSTS $344,160.50

EPA REGION III TRAVEL $1,024.77 EPA HEADQUARTERS TRAVEL 419.51 $1,444.28

FIELD INVESTIGATION TEAM CONTRACT $29,024.07 Ecology & Environment, Inc. 68-01-6056

FIELD INVESTIGATION TEAM CONTRACT $2,050.00 NUS Corporation 68-01-6699

REMEDIAL CONTRACT $26,041.00 NUS Corporation 68-01-6699

ALTERNATIVE REMEDIAL CONTRACT SERVICES NUS Corporation - 68-W8-0037 $672,219.91

CONTRACT LAB PROGRAM $16,925.07 68-01-7307

&R000699 INTERAGENCY AGREEMENT $8,243.21 Department of Interior DW 14038401 DW 14038201 DW 14196801

ENVIRONMENT EMERGENCY RESPONSE UNIT CONTRACT $31,081.17 68-03-3255 68-03-3482

TECHNICAL ENFORCEMENT SUPPORT CONTRACT $36,919.00 GCA - TES I 68-01-6769

TECHNICAL ENFORCEMENT SUPPORT CONTRACT $28,755.30 CDM - TES III 68-01-7331

TECHNICAL ENFORCEMENT SUPPORT CONTRACT $7,807.90 CDM - TES VII 68-W9-0004

STATE MANAGEMENT ASSISTANCE $23,000.00 AGREEMENT V-003431-01

INTERAGENCY AGREEMENT $5,418.33 U.S. ARMY CORPS OF ENGINEERS DW 96934515-0

INTERAGENCY AGREEMENT $6,127.37 U.S. DEPARTMENT OF JUSTICE DW 15365401

MISCELLANEOUS EXPENSES $533.17

TOTAL EPA BJPBllDITURBg THEOOQH 9/9/901 SI.412.126.

AR000700 NARRATIVE 8UMMAJIY/STATEMB1IT OF FACTS COSTS FOR THE ABMY CREEK SITE MEW CASTLE COUNTY, DB

Prepared by Leslie Vassallo/Charlene Arnold September 14, 1990

1. The United States Environmental Protection Agency has incurred costs of at least $162.397.68 for EPA Region III payroll.

2. The United States Environmental Protection Agency has incurred costs of at least $9.979.00 for EPA Headquarters payroll.

3. The United States Environmental Protection Agency has incurred costs of at least $344.160.50 for Agency Indirect Costs associated with personnel and overhead expenses required to support the Superfund program.

4. The United States Environmental Protection Agency haa incurred costs of at least $1.024.77 for EPA Region III travel.

5. The United States Environmental Protection Agency has incurred costs of at least $419.51 for EPA Headquarters travel.

6. The United Statee Environmental Protection Agency has incurred costs of at least S29.024.07 for Field Inveetigation Team (FIT) contract expendituree. Thie total repreeents the amount spent under the contract with Ecology 6 Environment, Inc.

7. The United Statee Environmental Protection Agency has incurred costs of at leeet S2.Q5Q.QQ for Field Inveetigation Team (FIT) contract expendituree. Thie total repreeente the amount spent under the contract with NUS Corporation.

8. The United Statee Environmental Protection Agency hae incurred costs of at leaet S26.04l.oo for Remedial (REM) contract expenditures. This total represents the amount spent under the contract with NUS Corporation.

AR00070I 9. The United Statee Environmental Protection Agency has incurred costs of at leaet S260.092.95 for Alternative Remedial Contract Services (ARCS) expendituree. This total represents a portion of the amount spent under the contract with NUS Corporation.

10. The United States Environmental Protection Agency has incurred costs of at least $16.925.07 for Contract Lab Program (CLP) expenditures. This total represents the coet of generating laboratory analysis of samples collected at the Army Creek Landfill.

11. The United States Environmental Protection Agency has incurred costs of at least S8.243.21 for Interagency Agreements (IAG) expenditures. This total represents the amount spent under the agreement with the U.S. Department of Interior.

12. The United Statee Environmental Protection Agency has incurred costs of at least $31.081.17 for Environmental Emergency Response Unit (EERU) contract expenditures. This total represents the amount spent under the contracts with Enviresponse and Roy F. Weston.

13. The United states Environmental Protection Agency has incurred costs of at least S36.919.00 for Technical Enforcement Support (TES I) contract expenditures. This total represents the amount spent under the contract with GCA Corporation.

14. The United States Environmental Protection Agency has incurred costs of at least $28.755.30 for Technical Enforcement Support (TES III) contract expenditures. This total represents the amount spent under the contract with Camp, Dresser & McKee.

15. The United States Environmental Protection Agency has incurred costs of at least $7.807.90 for Technical Enforcement Support (TES VIZ) contract expendituree. This total represents the amount spent under the contract with Camp, Dresser & McKee.

RR000702 16. The United Statee Environmental Protection Agency has incurred costs of at least S23.000.oo for State Management Assistance Agreement. This total represents the amount spent under the agreement with the State of Delaware.

17. The United States Environmental Protection Agency has incurred costs of at least S5.418.33 for Interagency Agreement (IAG) expenditures. This total represents the amount spent under the IAG with the U.S. Army Corps of Engineers.

18. The United Statee Environmental Protection Agency has incurred costs of at least S6.127.37 for Interagency Agreement (IAG) expenditures. This total represents the amount spent under the IA6 with the U.S. Department of Justice.

17. The United Statee Environmental Protection Agency hae incurred coets of at least S533.17 for Miscellaneous Expenses.

AR000703 COST SUMMARY REPORT ARMY CREEK SITE, DE Site 134

EPA EIPBHPITURB8t

EPA REGION III PAYROLL $162,397.68 EPA HEADQUARTERS PAYROLL 9.979.0O $172,376.68

INDIRECT COSTS $344,160.50

EPA REGION III TRAVEL $1,024.77 EPA HEADQUARTERS TRAVEL 419.51 $1,444.28

FIELD INVESTIGATION TEAM CONTRACT $29,024.07 Ecology & Environment, Inc. 68-01-6056

FIELD INVESTIGATION TEAM CONTRACT $2,050.00 NUS Corporation 68-01-6699

REMEDIAL CONTRACT $26,041.00 NUS Corporation 68-01-6699

ALTERNATIVE REMEDIAL CONTRACT SERVICES NUS Corporation 68-W8-0037 Work Assignment #37-07-3L34 $ 58,588.64 work Assignment I37-04-3N34 201.504.31 $260,092.95

CONTRACT LAB PROGRAM $16,925.07 68-01-7307

AROOQ701* INTERAGENCY AGREEMENT $8,243.21 Department of Interior DW 14038401 DW 14038201 DW 14196801

ENVIRONMENT EMERGENCY RESPONSE UNIT CONTRACT $31,081.17 68-03-3255 68-03-3482

TECHNICAL ENFORCEMENT SUPPORT CONTRACT $36,919.00 GCA - TES I 68-01-6769

TECHNICAL ENFORCEMENT SUPPORT CONTRACT $28,755.30 CDM - TES III 68-01-7331

TECHNICAL ENFORCEMENT SUPPORT CONTRACT $7,807.90 CDM - TES VII 68-W9-0004

STATE MANAGEMENT ASSISTANCE $23,000.00 AGREEMENT V-003431-01

INTZRAGENCY AGREEMENT $5,418.33 U.S. ARMY CORPS OF ENGINEERS DW 96934515-0

&RQ00705 INTERAGENCY AGREEMENT $6,127.37 U.S. DEPARTMENT OF JUSTICE DW 15365401

MISCELLANEOUS EXPENSES $533.17

TOTAL EPA EXPENDITURES CLAIMED THKOOOH S/»/»Ot $1,000.000.00

AROG0706 SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

EPA REGION III PAYROLL

Fiscal Year Hours Amount 1982 13 $162.90 1983 311 $4,152.73 1984 470 $7,805.36 1985 1,039 $16,446.92 1986 1,236.5 $21,024.40 1987 747.5 $13,373.34 1988 1,033.5 $17,037.67 1989 2,207.6 $37,100.37 1990 2,117.7 $45,293.99

TOTAL EPA REGION 11 S162.397.68

AR000707 EPA HEADQUARTERS PAYROLL

Fiscal Year Hours Amount

1982 7 $108.49 1983 45 $813.16 1984 214 $2,986.42 1985 165 $2,409.67 1986 35.5 $714.69 1987 21 $425.69 1988 62 $1,416.90 1989 31.5 $742.74 1990 14.5 $361.24

TOTAL EPA HEADQUARTERS PAYROLL? $9.979.00

TOTAL EPft PAYPiflFiIrf* $172.376.68

SOURCE OF INFORMATION: Financial Management System Software Package for Unique Reports (SPUR), dated 8/9/90

AR000708 SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

INDIRECT COSTS

Fiscal Total i of Hourly Fiscal Year Year Hour a Charged Rate Total

1983 311 $52.00* $16,172.00 1984 470 $52.00* $24,440.00 1985 1,039 $48.00* $49,872.00 1986 1,236.5 $47.00* $58,115.50 1987 598.5 $54.00* $32,319.00 1988 721.5 $54.00** $38,961.00 1989 1,079.5 $54.00** $58,293.00 1990 1,222 $54.00** $65,988.00

TOTAL EPA INDIRECT COSTS: S3 44.160.50 SOLttCE OF INFORMATION: Financial Management System Software Package for Unique Reports (SPUR), dated 8/9/90; Indirect Coet Rate Guidance Document, dated 7/8/85; Guidance Memorandum, dated 12/12/85, Re: Recovering Indirect Coat* Related to Superfund Site Cleanup; Superfund Indirect Coet Manual for Coet Recovery Purposes, dated March 1986; Superfund Indirect* Coet Update, dated 1/5/87; Superfund Final Indirect Coet Rates for Fiscal Years 1985 and 1986, dated 12/17/87; Sperfund Indirect Cost Rates for Fiscal Year 1987, dated 9/28/89

*Final Rate "Provisional Rate

AR000709 10

SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

EPA REGION III TRAVEL

FISCAL YEAR (FY) 1983 $1.50 1984 21.95 1985 204.50 1986 396.12 1987 47.60 1988 144.46 1989 188.00 1990 20.64

TOTAL EPA REGION III TRAVEL; $1.024.77

EPA HEADQUARTERS TRAVEL

FISCAL YEAR (FY) 1984 $41.75 1985 97.80 1987 23.06 1988 126.98 1990 129.92

TOTAL EPA HEADQUARTERS TRAVEL; $419.51

TOTAL EPA TRAVEL; 81.444.28

SOURCE OF IHFORMATIOM: Financial Management Syetea Software Package for Unique Reports (SPUR), dated 8/9/90

AR000710 11 SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

FTEIifl INVESTIGATION TEAM fFIT) CONTRACT CONTRACTOR: Ecology 6 Environment, Inc. CONTRACT f: 68-01-6056

SUMMARY OF WORK: Technical Direction Task nt fTDPl i F3-8107-07 Prepare and complete on-site inspection of the Llangollen Landfill F3-8108-16A Perform hydrogeological survey of F3-8108-16B Llangollen Site in New Castle County, Delaware F3-8110-14 Conduct a high priority eite inspec- tion of Llangollen Landfill F3 -82 06-10 Complete a Hazard Ranking System (HRS)

TOTAL CONTRACTOR COSTS; 829.024.07 •> •.

SOURCE OF INFORMATION Financial Management System Software Package for Unique Reports (SPUR), dated 8/9/90; Copies of TDDs and Acknowledgments of Completion 12

SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

FIELD INVESTIGATION TEAM fFITi CONTRACT CONTRACTOR: NUS Corporation CONTRACT |: 68-01-6699

SUMMARY OF WORK:

Technical Direction Taak TDD I i F3-8212-15 Provide technical, hydrological assistance to EPA etaff in determinining further action F3-8409-01 Region III FIT provided technical assistance to EPA (enforcement support)

TOTAL CONTRACTOR COSTS; S2.Q5Q.QQ

SOURCE OF INFORMATION: Contractor Cost Report Prepared by NUS Corporation, dated 7/31/86

RR0007I2 13 SUMMARY OF COSTS ARMY CREEK SITE, DE Site #34

REMEDIAL fREMl CONTRACT CONTRACTOR: NUS Corporation CONTRACT : 68-01-6699

SUMMARY OF WORK: Work Assignment I: 01-3V34 A Remedial Action Maeter Plan (RAMP) was developed for the Army Creek Site; this study was performed to evaluate site data, define the need for any additional data and to develope a preliminary technical scope Amount: $21,714.00

Work Assignment f: 12-3V34 A Community Relations Plan was developed for the Army Creek Site Amount: $4,327.00

TOTAL CONTRACTOR COSTS; 826.041.00

SOURCE OF INFORMATION: Contractor Coet Report Prepared by NUS Corporation, dated 7/31/86

AR0007I3 14 SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

ALTERNATIVE REMEDIAL CONTACT SERVICES (ARCS! CONTRACTOR: NUS Corporation CONTRACT I: 68-W8-0037 SUMMARY OF WORK: Work Assignment f: 37-07-3L34 Technical Review of Documents Document Control 0 Obligation Payment TE0032 $40,000.00 $40,000.00 TE0009 $27,158.53 $18,558.98 TE0021 $247.00 $29.66

Total Work Assignment Costs: $58.588.64

Work Assignment #: 37-04-3N34 Remedial Deeign Document Co.-'crol t Obligation Payment RD0009 $80,000.00 ' $80,000.00 RD0019 $430,896.00 $121,504.31

Total Work Assignment Costs: $201,504.31

TOTAL CONTRACTOR COSTS CLAIMED; $260.092.95

Financial Management Syetem Software Package for Unique Reports (SPUR), dated 8/9/90; Copies of Work Assignment and Amendments; Procurement Request/Order

HR0007U 15 SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

CONTRACT LAB PROGRAM fCLP) CONTRACTOR: Viar CONTRACT #: 68-01-7253

SUMMARY OF WORK: Analysis of samples

Lab: CHEM Contract #: 68-01-7307 Amount: $2,363.00

Control i Obligation Payment FB0054 $14,562.07 $14,562.07

TOTAL CONTRACTOR COSTS; Sl6.925.07

SOURCE OF INFORMATION: Financial Management System Software Package for Unique Reports (SPUR), dated 8/9/90

AR0007I5 16

SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

INTERAGENCY AGREEMENT .IAG)

AGENCY: Department of Interior AGREEMENT Is: DW14038201 DW14196801 DW14038401

SUMMARY OF WORK: Preliminary Natural Resource Survey; Wetlands Survey

Areement i Paments Control t T2A013 DW14038401 $3,448.00 T2A017 DW14038201 $2,522.21 T2A362 DW14196801 $2,273.00

TOTAL IAG COSTS; S8.243.21

SOURCE OF INFORMATION: Financial Management System Software Package for Unique Reports (SPUR), dated 8/9/90

AR0007I6 17

SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

ENVIRONMENTAL EMERGENCY RESPONSE UNIT fEERUl CONTRACT CONTRACTOR: Enviresponse CONTRACT |: 68-03-3255 CONTRACTOR: Roy F. Weston, Inc. CONTRACT I: 68-03-3482

SUMMARY OF WORK: Surface Sampling Contract 68-03-3255: nt Obligation Payment Control i F2A132 $1,528.06 $1,528.06 F2A219 881.80 881.80 F2A498 163.54 163.54 GB0001 3,541.27 3,541.27

Total Contract Coets: $6,114.67

AR0007I7 18 EERU CONTRACT (cont.)

68-03-3482 Obligation Payment Control i

GB0002 $3,109.12 $3,109.12 GB0005 21,857.38 21,857.38 Total Contract Costs: $24,966.50

TOTAL CONTRACTOR COSTS; $31.081.17

SUPPORTING DOCUMENTATION: Financial Management System Software Package for Unique Reports (SPUR), dated 8/9/90 19

SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

TECHNICAL ENFORCEMENT SUPPORT (TES I) CONTRACT

CONTACTOR: GCA Corporation Technology Division, Inc. CONTRACT #: 68-01-6769

SUMMARY OF WORK: Work Assignment I 84-147 Potential Responsible Party Search Work Assignment i 84-326 Document Review

84-147 $17,122.00 84-326 $19,797.00

TOTAL CONTRACTOR COSTS; $36.919.00

SOURCE OF INFORMATION: Contractor Coet Report Prepared by GCA, dated 8/28/86; Copy of Work Assignment and Amendments

AR0007I9 20 SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

TECHNICAL ENFORCEMENT SUPPORT .TES III! CONTRACT CONTRACTOR: Camp, Dresser 6 McKee CONTRACT #: 68-01-7331

SUMMARY OF WORK: Work Assignment f CO3042 Responsible Party identification through interviews; locate and interview indivi- duals who were involved in the operation and/or transport and disposal of hazardous waste at the Army Creek Landfill

Obligation Payment Control t C30051 $16,360.06 $16,360.06 C30114 $293.50 $293.50 C30153 $10,422.35 $10,422.35 T30014 $1,670.65 $1,670.65 T30059 $8.74 $8.74

TOTAL CONTRACTOR COSTS; 828.755.30'

SUPPORTING DOCUMENTATION: Financial Management System Software Package for Unique Reports (SPUR), dated 8/9/90; Work Assignment 21 SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

TECHNICAL ENFORCEMENT SUPPORT fTES VII) CONTRACT CONTRACTOR: Camp, Dresser & McKee CONTRACT |: 68-W9-0004 SUMMARY OF WORK: Work Assignment IC03051 Locate and interview individuals who were involved in the operation of Army Creek Landfill, as well as with the operation, transportation and disposal of hazardous wastes at the Army Creek Landfill

Oliation Payment Control t TE0019 $7,212.38 $7,212.38 TE0205 $301.12 $301.12 TE0210 $294.40 $294.40

TOTAL CONTRACTOR COSTS; $7.807.90

SUPPORTING DOCUMENTATION: • Financial Management System Software Package for Unique Reports (SPUR), dated 8/9/90; Work Assignment

ARGQ0721 22

SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

STATE MANAGEMENT ASSISTANCE GRANT AGREEMENT: Superfund Support Agency Activitiee Multi-Site Cooperative Agreement AGREEMENT i: V-003431-01 STATE: State of Delaware

SUMMARY OF WORK: Provide management assistance during the Remedial Deeign ae requested by EPA

Obligation Payment Control i

TE0008 $33,365.00 $23,000.00 TE0218 $33,366.00 -0-

TOTAL GRANT COSTS; $23,,000.00

SOURCE OF INFORMATION: Financial Management System Software Package for Unique Reports (SPUR), dated 8/9/90; Copy of Agreement V-003431-Ol

&RGG0722 23

SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

INTERAGENCY AGREEMENT AGENCY: U.S. Army Corps of Engineers AGREEMENT I: DW96934515-0

SUMMARY OF WORK: Technical Assistance for the Remedial Design of the Army Creek Landfill

PflCVJitnt Obligation Payment Contro^ * RD0007 $15,000.00 $5,418.33

SOURCE OF INFORMATION: Financial Management System Software Package for Unique Reports (SPUR), dated 8/9/90; Copy of Interagency Agreement/Amendment

ARG00723 24

SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

INTERAGENCY AGREEMENT (IAG1 AGENCY: U.S. DEPARTMENT OF JUSTICE AGREEMENT f: DW 15365401

SUMMARY OF WORK: Legal assistance provided by the Department of Justice to EPA on caeee related to CERCLA

nt Obligation Pament Control t JA0002 $6,127.37 $6,127.37

SOURCE OF INFORMATION: Financial Management System Software Package for Unique Reports (SPUR) , dated 8/9/90 25

SUMMARY OF COSTS ARMY CREEK SITE, DE Site 134

MISCELLANEOUS EXPENSES

Procurement Request/Order I: 6W2811NALX Preparation of Contractor Cost Report Amount: $500.00

Procurement Request/Order I: 3PC0000301 Supplies and Materials Amount: $24.60

Procurement Request/Order f: 6IMP006510 Printing & Reproduction of Materials Amount: $8.57

TOTAL MTSglgt.LAJ^Qyg EXPENSES: $533.17

SUPPORTING DOCUMENTATION: Financial Management Syetem Software Package for Unique Reports (SPUR), dated 8/9/90

ARGG0725