Eming -:'= -——- • **-*Gl ENVIRONMENTAL FNGIN&RS, INC
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IMUS 20 Gannett f "eming -:'= -——- • **-*gl ENVIRONMENTAL FNGIN&RS, INC FINAL REPORT FOCUSED REMEDIAL INVESTIGATION ARMY CREEK LANDFILL SITE NEW CASTLE COUNTY, DELAWARE EPA WORK ASSIGNMENT NUMBER 37-10-3L34 CONTRACT NUMBER 68-W8-0037 NUS PROJECT NUMBER 1017 JANUARY 1990 AR30I260 FINAL REPORT FOCUSED REMEDIAL INVESTIGATION STUDY ARMY CREEK LANDFILL SITE NEW CASTLE COUNTY, DELAWARE EPA WORK ASSIGNMENT NUMBER 37-10-3L34 UNDER CONTRACT NUMBER 6B-W8-0037 JANUARY 1990 Prepared By; APProved AJUAJM//Y(iry/V"' -_______ —,-_________...,. "David L. Sheridan, P,E. Robett E, SCeclk, Jr Project Manager ARCS III Program Manager Gannett Fleming, Inc. NUS Corporacloji| pgg TABLE OF CONTENTS -* Section Pa&e EXECUTIVE SUMMARY.,.,...,,,,......,.,,,..,,....,.,,....,.,.,,,......, ES-1 1.0 INTRODUCTION...,........,,,.,,,,.,.,,,..,...,,......,...,,.,..., 1-1 1,1 PURPOSE OF REPORT,..,.......,........,..,,..,.....,.... 1-1 1,2' SCOPE AND OBJECTIVES..........,,..,,.,.....,,........., 1-1 1.3 SITE BACKGROUND,,..,,,...,.....,....,,,,,,.,,....,..... 1-2 1.3.1 Sice Location and Description,.,,,..,,.....,,...,....., 1-2 1.3.2 Site History.,.,.,.............,.,...,.,,,..,...,...... 1-4 1,3.3 Previous Investigations,...,,.,......,......,,,,,...... 1-5 1,4 REPORT ORGANIZATION...........,,....,.,,.,...,..,,,.... 1-6 2,0 FIELD INVESTIGATION..,,....,,.,.,,...,...,,,..........,.,,....,. 2-1 2.1 SAMPLING OF GROUNDWATER RECOVERY WELL DISCHARGES,...... 2-1 2.2 HYDROGEOLOGIC INVESTIGATION............................ 2-3 3.0 NATURAL AND PHYSICAL CHARACTERISTICS OF THE SITE..,.,......,..,. 3-1 3.1 SURFACE FEATURES.,....,.,.,.......,,.,.........,,,,.... 3-1 3.2 CLIMATOLOGY...,,.,.,.....,..,..,.....,.............,,,. 3-1 3,3 GEOLOGY................................................ 3-3 » 3.3,1 Regional Geology.,...,..,...,,.,.....,,..,,,,.......... 3-3 3,3.2 General Sice Geology,..,,.,..........,..,,,,.,,.,...... 3-4 3,4 HYDROCEOLOGY.,,,...,..,...,.,.,.....,..,.,..,........,, 3-7 3,4,1 Aquifer Characteristics..,.........,,,,.,,,.,.,..,,.,,, 3-7 3.4,2 Groundwater Flow.,....,,.,,,,.,...,...........,,,.,.... 3-6 3,4,3 Water Balance Inventory.,,,,,....,,,,,,..,.,..,,,,,.... 3-9 3,4.4 Conclusions,,,,..,,,,..,.,..,.,,.,..,,.,,,..,.,,,....,. 3-11 3,5 DEMOGRAPHY AND LAND USE................................ 3-U 3.6 BIOTA,.....,,.....,,,,,,,,,,...,.,....,..,,,,,,....,,,, 3-13 3,6,1 Vegetation.,,,,....,,.,...,.........,.,....,,.,,,,..... 3-13 3,6.1,1 Direct Observations,,,,,,.,.,.,,,,....,....,,..,.,.,.., 3-13 3,6,1,2 Regional, Threatened, and Endangered Species,,,,,...,,, 3-17 3,6,2 Wildlife.,.,,,...,.,,,,,.,,,.,,...,.,,,,.,..,,....,.... 3-18 3.6.2,1 Amphibians and Reptiles.,,,,..,,,,,.,.,..,,,...,,,...., 3-18 3,6.2.2 Fish.....,.,.,.,.,,,.... ....,...,,...,..,,.....,....,, 3-20 3,6,2.3 Birds,,..,,,,,,.,.,,.,,.,.,...,......,,..,.,..,,.,...,. 3-22 3,6.2.4 Mammals.,,.,,,.....,,.,.....,.,...,...........,,.,..... 3-25 3.6.3 Aquatic Microbiota ,,.,,.,,,,...,,,.,.........,......,, 3-28 4,0 NATURE AND EXTENT OF CONTAMINATION.,...,,.,..,,...,.,.,,,,,,.,,, 4-1 4,1 GROUNDWATER RECOVERY WELL DISCHARGES,.,,.,.,.,,,.,.,.,, 4-1 4,2 SURFACE WATER AND SEDIMENTS...,.,..,...,...,,.,,.,..... 4-6 4.2.1 Surface Water,,.,.,,,.,,.,.,,,,.,.,....,,.,,,.,,,.,,.., 4-7 4.22 Sediments,,,,,,...,,,,,,,,.,,.,.,.,,,,........,..,,..., 4-7 AR30I262 TABLE OF CONTENTS (oont'd.) Seeclop Page 5.0 ENVIRONMENTAL FATE AND TRANSPORT,,,,,....,....,...............,, 5-1 5,1 CONTAMINANT TRANSPORT WITHIN A MEDIUM ................. 5-1 5.2 TRANSFORMATION OF CONTAMINANTS ..,...,,...,..,,.,...,,, 5-2 5.3 INTERMEDIA TRANSPORT OF CONTAMINANTS ,.......,...,...,. 5-5 5,3,1 Transfer between Water and Atmosphere ,,..,..,,,,,,.,,, 5-5 5,3.4 Transfer between Water and Sediment/Soil .,.,,...,.,.., 5-8 5.3,3 Transfer between Wacer/Sedlmenc and Biota .,,.,......,. 5-12 5.4 SUMMARY .,,..,..,,,..,....,,...,..,,..,.....,,.,,...,., 5-13 6.0 RISK ASSESSMENT..........,..,.,.......,..,.........,..,,.,..,... 6-1 6.1 HAZARD ASSESSMENT ,,,,......,,......,.....,,.,..,,..,.. 6-1 6.1.1 Hazard Identification .....,..,,..,..........,.,.,...,. 6-2 6,1,2 lexicological Evaluation .....,...,,...,,...,.,..,.,,,. 6-3 6,2 DOSE-RESPONSE EVALUATION ..,...,,.,....,......,..,.,,.. 6-4 6,2.1 Toxicity Values ,.,,,,.........,...,,,.,.,.,..,,.,...,, 6-4 6,2.2 Water Quality Criteria ...,..,..,,.,.,...,,..,...,.,,.. 6-6 6,3 EXPOSURE ASSESSMENT ................................... 6-10 6,3.1 Receptor Identification ..,,....,.,,..,,....,........,. 6-12 6.3.2 Exposure Routes ,,,,,.,..,,..,,.,...,,..,..,....,,.,,.. 6-12 . 6,3.3 Exposure Estimates ,..,..,,,.,,,,,..,..,.,.,.,,.,,.,.,, 6-13 6,4 RISK CHARACTERIZATION .,,,,,,......,.,,....,.,.....,,., 6-18 6,4.1 Uncertainty in Risk Assessment ,.,..,.,,,,,,..,.,..,.., 6-18 6.4,2 Carcinogenic Risks ,....,..,.,..,,.,,,,..,.,.,..,..,,.. 6-19 6.4,3 Koncarcinogenic Effects ,...,.,.,..,,..,..,,..,,...,,,, 6-20 6.4.4 Summary of Risk Characterization ,,,...,,,.,,,,,.,,,,,, 6-20 6,5 ENVIRONMENTAL ASSESSMENT ...,...,,,,,,.....,.,...,..... 6-20 6,5.1 Water Quality ....,,..,....,..,..,.,,.,,,..,..,,,,.,.,, 6-20 6.5,2 Bioassays and Chronic Toxicity Studies ,..,,.,,,,,,,.,, 6-23 6,5,3 Chemicals of Concern and Environmental Receptors,,,.,,, 6-25 7,0 SUMMARY AND CONCLUSIONS ..,,,..,.,..,,.,,.,.,..,...,,..,,,..,,,. 7-1 7,1 SUMMARY ..,,,....,.,,.,..,...,,.,.......,,.,...,..,,,., 7-1 7.1,1 Nature and Extent of Contamination ,.....,...,..,...,., 7-1 7.1.2 Environmental Fata and Transport ,,.,.,,,..,,,.,,,,,.., 7-1 7.1.3 Risk Assessment ,,...,,,.,.,.,,.,,.,.....,...,.,..,,,., 7-2 7,2 CONCLUSIONS ,,.,,..,..,..,.,,.,.,,,......,.,.,,...,..., 7-2 u AR30I263 TABLE OF CONTENTS (cont'd.) Section^ Page REFERENCES........................................................... R-l APPENDICES A COMMUNITY RELATION CONCERNS AND MAILING LIST B SAMPLE LOG SHEETS C ANALYTICAL RESULTS FOR GROUNDWATER RECOVERY WELL DISCHARGES D PREVIOUS SEDIMENT AND SURFACE WATER DATA E TOXICOLOGIC PROFILES F PUBLIC HEALTH RISK CALCULATIONS G ENVIRONMENTAL SURVEY DATA H PRIME FARMLAND AND HISTORIC AND ARCHAEOLOGICAL RESOURCES AROUND THE ARMY CREEK LANDFILL SITE I LIST OF CONTRIBUTORS 111 LIST OF TABLES Table gflge 3-1 Vegetation of Array Creek ,...,........,.,.,,.,......,.... 3-14 3-2 Reptiles and Amphibians of Army Creek ..,,.,....,....,,,. 3-19 3-3 Fish of Army Creek .,,..,...,,.,,,.,..,.,..,.,..,..,,,.,. 3-21 3-4 Birds of Army Creek ..................................... 3-23 3-5 Mammals of Army Creek ......,....,.,....,..,.,..,......,. 3-26 3-6 Aquatic Invertebrates of Army Creek ,....,,,.,,.,,,.,..,. 3-29 4-1 Summary of Analytical Results for Recovery Well Discharge—General Chemical Characteristics...,,,...,,... 4-2 4-2 Summary of Analytical Results for Recovery Well Discharge--Total Inorganic Contaminants ,.,,.,......,..,. 4-3 4-3 Summary of Analytical Results for Recovery Well Discharge--Dissolved Inorganic Contaminants ,,,,,..,,,.,. 4-4 4-4 Summary of Analytical Results for Recovery Well Discharge-•• Organic Contaminants .,,,.,,,,.,,,.,..,,,..,.,...,..,..,, 4-5 4-5 Summary of Analytical Results for Previous Surface Vater Sampling--Organic Contaminants .,,,.,,,,,,...,....,,,..,. 4-8 4-6 Summary of Analytical Results for Previous Surface Water Sampling--Inorganic Contaminants ,,,...,.....,.....,.,.., 4-9 4-7 Summary of Analytical Results for Previous Sediment Sampling--Organic Contaminants ,.,,...,,....,,,.,,.,,,,., 4-10 4-8 Summary of Analytical Results for Previous Sediment Sampling--Inorganic Contaminants ,.,.,,,,,......,...,,,,, 4-11 4-9 Ranges and Averages of Metals in Uncontamlnated Soil ,,., 4-12 4-10 Comparison of Surface Water and Sediment Concentrations in Army Pond and Army Creek..,.......,.,.....,....,...,..,., 4-14 5-1 Relative Importance of Naturally-Occurring Processes for Selected Contaminants at the Army Creek Landfill Site ,., 5-3 5-2 Chemical and Physical Properties Affecting Contaminant Migration ,....,..,,,...,.,.,,,,......................... 5-6 5-3 Comparison of Observed and Calculated Surface Water Concentrations of Inorganic Contaminants,.,,,,,.,,,,,,,., 5-11 6-1 Regulatory Requirements and Dose-Response Parameters for Indicator Chemicals ,,,,,.,,,,,,.,,,.,,.,...,..,..,., 6-7 6-2 Water Quality Criteria for Indicator Chemicals .,,,.,.,., 6-11 6-3 Summary of Total Potential Carcinogenic Risks ........... 6-21 6-4 Summary of Total Potential Hazard Indices ,.,,,,.,,,,,,,, 6-22 6-5 Environmental Chemicals of Concern,,.,.,..,.,,.,......,., 6-26 iv AR30I265 LIST OF FIGURES Figure £S2£ 1-1 Army Creek Landfill Site Location ......................... 1-3 2-1 Army Creek Active Recovery Wells .......................... 2-2 3-1 Army Creek Landfill Site .................................. 3-2 3-2 Hypothetical Pre- and Post-Pumping Groundwater Flow Regime in the Vicinity of Army Creek ...................... 3-6 AR30I266 m 8x H m< U) 1 1 AR30I26? EXECUTIVE SUMMARY SITE HISTORY The Army Creek Landfill, formerly known as the Llangollen Landfill, is located approximately 7 miles southwest of the Cicy of Wilmlngton, Delaware, 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 U.S. Routes 13 and 301 to the west and Delaware Route 9 to the east, The Array Creek Landfill consists of a 60-acre site that was operated by New Castle County from 1960 through 1968 for the disposal of municipal and industrial wastes, The site is located adjacent to Delaware Sand and Gravel (DS&G), an industrial waste disposal site closed by the Delaware Department of Natural Resources and Environmental Control