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ADDENDUM TO THE PHASE I REMEDIAL INVESTIGATION WORK PLAN W.R. GRACE SUPERFUND SITE ACTON, MASSACHUSETTS
HSI January 14,2000 GEOTRANS A TETRA TECH COMPANY 6 Lancaster County Road, Suite Four Harvard, Massachusetts 01451 6 Lancaster County Road HSI Harvard, Massachusetts GEOTRANS 01451
A TETRA TECH COMPANY 978-772-7557 FAX 978-772-61 83
P.N. N099-007
January 13,2000
Mr. Derrick Golden Mr. Donald Hanson U.S. Environmental Protection Agency Bureau of Waste Prevention Region I MA Department of Environmental 90 Canal Street, Mail Code #HBO Protection Boston, MA 02203-0001 627 Main Street Worcester, MA 01608
Subject: Addendum to the Phase 1 Remedial Investigation Work Plan, W. R. Grace Superfund Site, Acton, Massachusetts
Gentlemen:
Enclosed please find the Addendum to the Phase 1 Remedial Investigation Work Plan. As indicated in the attached schedule, we will anticipate receiving comments from you on this document by March 14, 2000.
If you have any questions regarding this document, please call me at (978) 772-7557.
Sincerely,
Anne E. Benjamin Project Manager
Enclosures
AEB/blc
M \WP DOCS\N099\200OTI 11) 1015 »pd Derrick Golden and Donald Hanson 2 January 13,2000
cc: Seth Jaffe, Esq.. Foley. Hoag & Eliot Andy Cohen, DEP Boston Jim Demming, Action Water District Bob Eisengrein, ACES Doug Halley, Town of Acton Stephen Anderson, Anderson and Kreiger Maryellen Johns, W.R. Grace & Co. - Conn. Gretchen Muench, Esq. U.S. EPA Chuck Myette, EMCON Jim Okun, OT&O Barbara Weir, Metcalfe & Eddy J. Swallow, Pine & Swallow Associates Mitch Obradovic, W. R. Grace & Co. - Conn. Acton Public Library Nancy Bettinger, DEP Office of Research and Standards
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cc ADDENDUM TO THE PHASE I REMEDIAL INVESTIGATION WORK PLAN
W.R. GRACE SUPERFUND SITE ACTON, MASSACHUSETTS
PREPARED FOR: W.R. GRACE & Co. - CONN. 62 WHITTEMORE AVENUE CAMBRIDGE, MA 02140
PREPARED BY: HSI GEOTRANS, INC. 6 LANCASTER COUNTY ROAD HARVARD, MASSACHUSETTS 01451
HSI GEOTRANS PROJECT No. N099-007 JANUARY 14,2000
HSI GeoTrans, inc. TABLE OF CONTENTS PAGE
1 BACKGROUND 1-1 1.1 INTRODUCTION 1-1 1.2 NORTHEAST AREA 1-2 1.2.1 AIRCO INDUSTRIAL - ACTON, MA 1-2 1.2.2 PUBLIC WATER SUPPLY WELLS 1-2 1.3 HYDROGEOLOGIC SETTING 1-4 1.3.1 REGIONAL SETTING 1-4 1.3.2 SITE HYDROGEOLOGY 1-5 1.3.2.1 GEOLOGY 1-5 1.3.2.2 GROUNDWATER FLOW 1-6 1.3.2.3 HYDRAULIC PROPERTIES 1-7 1-7 1.3.2.4 FORT POND BROOK 1-8 1.4 GROUNDWATER QUALITY 1-8 1.5 FORT POND BROOK WATER QUALITY 1-11 1.6 SUMMARY 1-11 2 SITE CHARACTERIZATION 2-1 2.1 SITE SURVEY 2-1 2.2 SUBSURFACE AND HYDROGEOLOGIC INVESTIGATIONS 2-1 2.2.1 MONITORING WELL INSTALLATION 2-3 2.2.2 MISCELLANEOUS ACTIVITIES 2-5 2.3 SURFACE WATER AND SEDIMENTS 2-6 2.4 LONG-TERM MONITORING 2-6 2.5 TREATABILITY AND PILOT STUDIES 2-6 3 REFERENCES 3-1 APPENDIX A WATER QUALITY SUMMARY TABLES APPENDIX B ADDITIONS TO PROJECT OPERATIONS PLAN
FOR W R GRACE & Co - CONN. _ M\WP_DOCS,NCK»\2000\I20I0820*TO 11 HSI OGO I TSHS, IDC. LIST OF TABLES PAGE TABLE 1-1. SUMMARY OF COMPOUNDS DETECTED PRIOR TO 1999 NORTHEAST OF THE GRACE PROPERTY (MW AND PS SERIES WELLS, CHRISTOFFERSON. LAWSBROOK AND SCRIBNER WELLS) 1-13 TABLE 1 -2. SUMMARY OF COMPOUNDS DETECTED IN 1999 NORTHEAST OF THE GRACE PROPERTY (MW SERIES WELLS, CHRISTOFFERSON, LAWSBROOK AND SCRIBNER WELLS) 1-15 TABLE A-1. SUMMARY OF COMPOUNDS DETECTED PRIOR TO 1999 NORTHEAST OF THE GRACE PROPERTY (MW AND PS SERIES WELLS, CHRISTOFFERSON, LAWSBROOK AND SCRIBNER WELLS) (SORTED BY LOCATION) APP-A-1 TABLE A-2. SUMMARY OF COMPOUNDS DETECTED PRIOR TO 1999 NORTHEAST OF THE GRACE PROPERTY (MW AND PS SERIES WELLS, CHRISTOFFERSON, LAWSBROOK AND SCRIBNER WELLS) (SORTED BY COMPOUND) APP-A-7 TABLE A-3. SUMMARY OF COMPOUNDS DETECTED PRIOR TO 1999 NORTHEAST OF THE GRACE PROPERTY (MW SERIES WELLS, CHRISTOFFERSON, LAWSBROOK AND SCRIBNER WELLS)(SORTED BY LOCATION) APP-A-12 TABLE A-4. SUMMARY OF COMPOUNDS DETECTED PRIOR TO 1999 NORTHEAST OF THE GRACE PROPERTY (MW SERIES WELLS, CHRISTOFFERSON, LAWSBROOK AND SCRIBNER WELLS)(SORTED BY COMPOUND) ... . APP-A-13 TABLE B-l. PROPERTIES FOR WHICH ACCESS MAY BE REQUIRED APP-B-2 TABLE B-2. SITE-WIDE WATER LEVEL MONITORING LOCATIONS APP-B-3 TABLE B-3. GROUND WATER SAMPLING LOCATIONS AND ANALYSES APP-B-4 TABLE B-4. PROPOSED ADDITIONAL MONITORING WELL LOCATIONS APP-B-6 TABLE B-5. SOIL SAMPLING LOCATIONS FOR TOC ANALYSIS APP-B-7
FOR W.R. GRACE & Co. - CONN. M \WP DOCS\NOW2000\ 12010820 WPD 111 HSI GeoTrans, inc. LIST OF FIGURES PAGE FIGURE 1-1. SITE AND SURROUNDING AREAS 1-17 FIGURE 1 -2. UNCONSOLIDATED DEPOSITS POTENTIOMETRIC CONTOUR MAP 1999 ... 1-18 FIGURE 1-3. BEDROCK POTENTIOMETRIC CONTOUR MAP 1999 1-19 FIGURE 1 -4. AVERAGE VDC, VINYL CHLORIDE AND BENZENE CONCENTRATIONS IN UNCONSOLIDATED DEPOSITS 1986 & 1990 1-20 FIGURE 1 -5. AVERAGE VDC, VINYL CHLORIDE AND BENZENE CONCENTRATIONS IN BEDROCK 1986 & 1990 1-21 FIGURE 1-6. CROSS SECTION A-A' (DATA FROM 1986 & 1990) 1-22 FIGURE 1 -7. VDC, VINYL CHLORIDE AND BENZENE CONCENTRATIONSIN UNCONSOLIDATED DEPOSITS 1999 1-23 FIGURE 1 -8. VDC, VINYL CHLORIDE AND BENZENE CONCENTRATIONS IN BEDROCK 1999 1-24 FIGURE 1-9. CROSS SECTION A-A' (DATA FROM 1999) 1-25 FIGURE 2-1. PROPOSED EXTENSION OF THE TOPOGRAPHIC MAP 2-7 FIGURE 2-2. SCHEMATIC OF 1999 VDC CONCENTRATIONS IN GROUNDWATER 2-8 FIGURE 2-3. SITE MAP WITH PROPOSED SAMPLING LOCATIONS 2-9 FIGURE B-1. PROPERTIES FOR WHICH ACCESS MAY BE REQUIRED APP-B-8
FOR W.R. GRACE & Co. - CONN. M\WP DOCS\N099\2000M 2010820 WPD IV HSI GeoTrans, inc. LIST OF ACRONYMS AND ABBREVIATIONS
Addendum Addendum to the Phase 1 Remedial Investigation Work Plan cfs cubic feet per second gpm gallons per minute Grace W. R. Grace & Co. - Conn. ISCR Initial Site Characterization Report, Operable Unit Three NGVD National Geodetic Vertical Datum of 1929 MADEP Massachusetts Department of Environmental Protection PCE Tetrachloroethene POP Project Operations Plan RI/FS Remedial Investigation/Feasibility Study RI Work Plan Phase 1 Remedial Investigation Work Plan Site W. R. Grace & Co. - Conn. Acton Superfund Site SOW Statement of Work TCA 1,1,1 -trichloroethane TCE Trichloroethene TOC Total Organic Carbon USGS United States Geological Survey VDC 1,1 ,-dichloroethene Zone 2 MADEP Approved Wellhead Protection Area
FOR W.R. GRACE & Co. - CONN. M\WP DOCS\N099\2000\I2010820 WPD HSI GeoTrans, inc. 1 BACKGROUND
1.1 INTRODUCTION
The Addendum to the Phase 1 Remedial Investigation Work Plan (the Addendum) for the W. R. Grace & Co. - Conn. (Grace) Acton Superfund Site (the Site) is submitted to address the area northeast of the Grace property. One of the tasks proposed in the Phase 1 Remedial Investigation Work Plan (RI Work Plan) (HSI GeoTrans, 1999a) was to obtain and review available water level and water quality data from the Airco Industrial site located northeast of the Grace property (Figure 1-1). Grace completed this task while the government parties were reviewing the RI Work Plan. The results of the data review indicate that additional data should be collected during the RI to better understand the groundwater flow direction and the nature and extent of groundwater contamination in the area northeast of the Grace property. Grace is submitting this Addendum so that uncertainties regarding groundwater contamination northeast of the Grace property can be addressed during the Phase 1 RI, rather than during a subsequent investigation. The objectives of the Addendum are to
• review existing data in the area of the Airco Industrial site, review existing data in the area of the Lawsbrook, Scribner and Christofferson public water supply wells located northeast of the Airco Industrial site (Figure
1-D, • identify uncertainties regarding the flow of groundwater and the distribution of groundwater contamination in the area northeast of the Grace property, and • propose specific investigations designed to address the identified uncertainties.
Section 1 of the Addendum summarizes existing data from the area northeast of the Grace property and identifies uncertainties regarding the flow of groundwater and the
FOR W.R. GRACE & Co. - CONN. M \WP_DOCS\N099\2000\I20I0820WPD Hoi , IDC. distribution of groundwater contamination. Section 2 of the Addendum proposes specific investigations designed to address the identified uncertainties.
1.2 NORTHEAST AREA 1.2.1 AIRCO INDUSTRIAL - ACTON, MA The Airco Industrial site is located directly north of the former W.R. Grace Daramic Plant on Lawsbrook Road in Acton, Massachusetts (Figure 1-1). Airco's acquisition of this land in 1948 was the first time this property had been used for industrial purposes. The facility, now operated by BOC Gases, is located within an Approved Wellhead Protection Area (Zone 2). The Airco Industrial site is approximately 1,600 feet hydraulically upgradient from the Lawsbrook and Scribner public water supply wells.
Several unconsolidated deposits and bedrock monitoring wells have been installed at the Airco Industrial site in response to Airco Industrial site-related contamination. Groundwater quality data collected sporadically from these wells since 1987 suggest that Airco Industrial site-related contamination is limited mainly to groundwater in the shallow unconsolidated deposits and that contamination in the bedrock groundwater is not related to Airco Industrial site contamination. A more complete description of the production history of the Airco Industrial site and the Airco Industrial site-related contamination can be found in Section 2.2.1 of the Initial Site Characterization Report, Operable Unit Three (ISCR) (HSI GeoTrans, 1998).
1.2.2 PUBLIC WATER SUPPLY WELLS The Lawsbrook, Scribner, and Christofferson public water supply wells, which are operated by the Acton Water District, are located between School Street and Lawsbrook Road in Acton, Massachusetts (Figure 1-1). The wells are approximately 3,700 feet northeast of the Grace property.
FOR W R GRACE & Co - CONN M \WP_DOCS\N099\2000\I20I0820WPD 1 "2 HSI GGOTTdnS, IRC. The Christofferson well, formerly called the School Street well, is located immediately north of Fort Pond Brook (Figure 1-1). The well, installed in 1964, is 40 feet deep with an eight-inch diameter casing and a ten-foot long gravel packed screen. The maximum sustainable pumping rate for the Christofferson well, when all three public water supply wells are pumping, has been estimated to be 300 gallons per minute (gpm) (GZA, 1984).
The Lawsbrook well, constructed in 1960, is located approximately 1,000 feet south of Fort Pond Brook (Figure 1-1). The well is 24-inches in diameter in a 48-inch diameter gravel packed borehole. The well is 53 feet deep with a ten-foot screen. The maximum sustainable pumping rate for the Lawsbrook well, when all three public water supply wells are pumping, has been estimated to be 208 gpm (GZA. 1984). The Lawsbrook well is classified as an emergency source because the Acton Water District does not own the 400 foot protective radius around the well.
The Scribner wellfield, also referred to as the Lawsbrook wellfield, is located approximately 150 feet south of Fort Pond Brook (Figure 1-1). The wellfield is comprised of eighteen 2 '/2-inch diameter gravel packed wells. The wellfield consists of three parallel lines with six, eight and four wells, respectively. The wells, which range in depth from 26 to 35 feet deep, have five-foot long screens and are spaced approximately fifty feet apart. The maximum sustainable pumping rate for the Scribner wellfield, when all three public water supply wells are pumping, is approximately 236 gpm (GZA, 1984).
Water from the Christofferson well, the Lawsbrook well, and the Scribner wellfield is treated at the School Street Treatment Plant, located on School Street, west of Route 2 and near the Christofferson well. The treatment facility was constructed in 1987 to remove VOC's which have been detected in groundwater from the wells. VOCs which have been detected include: 1,1,1-trichloroethane (TCA), 1,1-dichloroethane, 1,1-dichloroethene
FOR W.R. GRACE & Co. - CONN. M \WPJX3CSW099\2000M20I0820 *TO 1-3 HSI GGOTTdDS, IDC. (VDC), chloroform, benzene and trichloroethene (TCE). The water is treated using an air- stripper. The treatment plant has a capacity of 620 gpm (Dufresne-Henry, 1996).
1.3 HYDROGEOLOGIC SETTING 1.3.1 REGION AL SETTING The approximately 260 acre property owned by Grace is located in Acton and Concord, Massachusetts (Figure 1-1). Fort Pond Brook borders the Grace property to the northwest and the Assabet River borders the Grace property to the southeast. Two Acton public water supply wells, Assabet 1 and Assabet 2. are located south of the Grace property, and three Acton public water supply wells, Christofferson, Lawsbrook and Scribner, are located northeast of the Grace property.
The geomorphology of the Site and surrounding areas is characterized by glacial features including kames, swampy areas, and kettlehole ponds. The surficial geology of the area is comprised predominantly of stratified glacial deposits. Sand and gravel deposits are underlain by glacial till, which is underlain by metamorphic bedrock. The bedrock is comprised of gneisses and schists of the Nashoba formation. The upper portion of the bedrock has been observed to be weathered and fractured (Hansen, 1956). The Site is located between two major northeast trending fault zones, the Bloody Bluff and the Clinton- Newbury. These major fault zones have created a northeast trending regional fabric of stratigraphic trends and foliation (Barosh, Fahey and Pease, 1977).
The Site is located in the Assabet River Drainage Basin which is part of the larger Merrimack River Basin. Water within this drainage system eventually discharges to the Atlantic Ocean north of Cape Ann (Pollock, 1969).
Recharge from precipitation is the principal source of water to the aquifer. Between 1957 and 1997, the average annual recorded precipitation was about 45 inches per year.
FOR W.R. GRACE & Co. - CONN. M\wp_Docs\Now2ooo\i2oios2owpD 1-4 HSI GsoTfans, inc. Precipitation was recorded at the National Weather Service Station in Bedford, Massachusetts located approximately 8 miles to the east. During this period the highest measured annual precipitation was 61.22 inches in 1996 and the lowest was 27.25 inches in 1965. On average, the greatest monthly precipitation occurs in November, with 4.5 inches and the lowest occurs in June, with 3.3 inches (NOAA, 1997).
1.3.2 SITE HYDROGEOLOGY The hydrogeology of the Grace property and surrounding areas was presented in the ISCR. This section will focus on the hydrogeology of the area northeast of the Grace property. Subsurface investigations completed during previous investigations have provided information on the geologic and hydraulic characteristics of the unconsolidated deposits and the bedrock in the area northeast of the Grace property. This information is summarized below.
1.3.2.1 GEOLOGY Bedrock The bedrock near the Site has been identified as gneisses and schists of the Nashoba formation. As described in boring and well logs, the bedrock consists of gray to green foliated quartz-biotite gneiss and quartz schists. The bedrock has both vertical and horizontal fracturing. Data from wells drilled into bedrock at the Airco Industrial site indicates that the bedrock surface in that area ranges from 93 to 137 feet below ground surface and from an elevation of 96 to 54 feet National Geodetic Vertical Datum of 1929 (NGVD). Refusal data from wells completed in the unconsolidated deposits near the Lawsbrook, Christofferson and Scribner wells, indicates that the bedrock surface in that area ranges from 30 to 100 feet below ground surface and ranges in elevation from 120 to 64 feet NGVD.
Unconsolidated Deposits Boring logs from the Airco Industrial site indicate that there is a dense silt with some fine sand and clay overlying the bedrock. The silt ranges in thickness from four to 55 feet. Overlying the silt are stratified units consisting mainly of fine to medium sands with coarse
FOR W R GRACE & Co - CONN ~~~ " ~ M \wp_Docs\N099V2oooM2oio82owro 1-5 HSI GooTratis, inc. sand, silt and gravel in some areas. The sands range from 76 to 133 feet thick. No stratigraphic information is available from the area near the Lawsbrook, Christofferson and Scribner wells, except that the Lawsbrook and Scribner wells are located in a former gravel pit.
1.3.2.2 GROUNDWATER FLOW Figures 1-2 and 1-3 illustrate water levels measured between September 27 and 30, 1999 in wells screened in the unconsolidated deposits and in bedrock, respectively. The figures show that groundwater on the Grace property currently flows from a groundwater high located in the vicinity of the MBTA easement and Independence Road to the south and southeast toward the Assabet River and to the northwest toward Fort Pond Brook. Groundwater levels and flow directions are locally affected by recharge from surface water bodies, such as Sinking Pond, and groundwater withdrawals from municipal and extraction wells. A detailed discussion of groundwater flow conditions at the Grace Site is included in the ISCR.
The data available to the northeast of the Grace Site indicate that the groundwater divide currently extends to the north across portions of the Airco Industrial site. The data show a groundwater mound in the unconsolidated deposits near wells MW-10S and MW-7, with groundwater flowing to the north across the northern portion of the Airco Industrial site (Figure 1-2). As shown in Figure 1-3, groundwater flow in bedrock beneath the Airco Industrial site is to the north with a low horizontal hydraulic gradient. Data collected in 1986, north of the Airco Industrial site in the PS series wells, indicates groundwater flow in the unconsolidated deposits to the north and northeast toward Fort Pond Brook and the ^' Lawsbrook well.
Water level data indicate that there are downward vertical hydraulic gradients between the shallow and deep unconsolidated deposits at the Airco Industrial site at all locations except the MW-6 and MW-4 clusters where there is an upward vertical hydraulic gradient. There is a downward vertical hydraulic gradient between the unconsolidated
FOR W.R. GRACE & Co. - CONN. " ~~~ ~ M \wp_Docs\NW2ooo\ 12010820 wo 1-6 HSI GsoTpans, inc. deposits and the bedrock at the Airco Industrial site. Data collected from the PS series wells in 1986 indicate that there are strong upward vertical hydraulic gradients in the unconsolidated deposits along Fort Pond Brook. These data support the conclusion that groundwater discharges to the brook (Pine and Swallow, 1986). There are no bedrock wells in the area north of the Airco Industrial site near the Lawsbrook, Scribner and Christofferson public water supply wells.
The location of the groundwater divide and groundwater flow directions in the area northeast of the Grace Site have likely changed over time in response to the cessation of wastewater disposal in the lagoons at the Grace Site and temporal variations in groundwater withdrawal from municipal and extraction wells.
1.3.2.3 HYDRAULIC PROPERTIES In May 1959, a pumping test was done on a test well near the current location of the Lawsbrook well. The test well was pumped for nine days at 200 gpm and the drawdown response was measured in three monitoring wells. Analysis of the pumping test data indicated that the hydraulic conductivity in the vicinity of the Lawsbrook well is approximately 180 feet per day (Water Supply District of Acton files). A pumping test was conducted in August 1963 on a test well near the location of the current Christofferson well. The test well was pumped for nineteen days at 400 gpm and drawdown was measured in four monitoring wells. Analysis of the pumping test data indicated that the hydraulic conductivity in the vicinity of the Christofferson well is approximately 55 feet per day (Water Supply District of Acton files). A pumping test was done in 1979 at the Scribner wellfield. Twelve wells in the wellfield were pumped at 280 gpm for 21 days. Drawdown was measured at eight monitoring wells. Analysis of the pumping test data indicated that the hydraulic conductivity in the vicinity of the Scribner wellfield is approximately 24 feet per day. The pumping test also indicated that Fort Pond Brook provides a limited amount of recharge to the Scribner wellfield (Dufresne-Henry,1981).
FOR W.R. GRACE & Co. - CONN. M\WP_DOCS\N099UOOOV 12010820 »TD 1-7 HSI GGOTrSflS, JRC. TARGET SHEET
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DESCRIPTION: Figure 1-2: Unconsolidated Deposits Potentiometric Map 1999
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DOC ID: 43194 DATE: January 14, 2000 TITLE: Addendum to the Phase 1 Remedial Investigation Work Plan
DESCRIPTION: Figure 1-4: Average VDC, Vinyl Chloride And Benzene Concentrations in Unconsolidated Deposits 1986& 1990
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DESCRIPTION: Figure 1 -5: Average VDC, Vinyl Chloride and Benzene Concentrations in Bedrock 1986 & 1990
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DESCRIPTION: Figure 1-7: VDC, Vinyl Chloride and Benzene Concentrations in Unconsolidated Deposits 1999
THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER, BOSTON, MA TARGET SHEET
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DESCRIPTION: Figure 1-8: VDC, Vinyl Chloride and Benzene Concentrations in Bedrock 1999
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UJ £ a S •s > CD BEDR O o: §— '\ ^2 \ i Wz "~C•". \\ y™r^iM * i • • ITir™ i •••• • i / T 1M T CO i 'i CQ CM CO I O 9 / i i 01 O 01 It O D * Q r° CO co LU Q dOM NOU03S-X\*aOM\Slc 2 SITE CHARACTERIZATION Section 2 is divided into the five components of Site characterization identified in the Operable Unit Three Remedial Investigation/Feasibility Study (RI/FS) Statement of Work (SOW). Section 2.1 is the Site survey, Section 2.2 is the subsurface and hydrogeologic investigations, Section 2.3 is surface water and sediments. Section 2.4 is long-term monitoring and sampling and Section 2.5 is treatability and pilot studies. 2.1 SITE SURVEY The SOW requires the preparation of a small-scale map based on the United States Geological Survey (USGS) 7.5-minute quadrangle, as well as, a topographic contour map of the Site. The small-scale map based on the USGS quadrangle is complete. The existing Site topographic map extends as far north as the Airco Industrial site. The topographic map will be extended to include the area of the Christofferson, Lawsbrook and Scribner wells. Figure 2-1 shows the extent of the existing topographic map and the area that will be added to the map. 2.2 SUBSURFACE AND HYDROGEOLOGIC INVESTIGATIONS The SOW requires that sufficient subsurface and hydrogeologic investigations be planned, conducted and reported to characterize and/or describe, at a minimum, the following: The nature and extent of contamination sufficiently to define the boundaries of all contaminant plumes and to quantify in three dimensions every aquifer, including bedrock; A quantitative estimate of the number of years necessary to achieve clean-up goals for ground water extraction and treatment remedial alternatives; FOR W. R. GRACE & Co. - CONN. M \WPDOCS\N099\2000\12010820WPD 2~ 1 HSI CjGOirSnS, IMC. The subsurface stratigraphy and structure, for each rock and soil type including, but not limited to, lithologies, grain sizes, sorting, permeability, fracturing (orientation, frequency, and effects), plasticity index, moisture content, dry density, and mineralogy; The concentration, environmental fate, transport mechanisms, and other significant characteristics of each contaminant; The partitioning of contaminants between groundwater and soil or rock, and determine the phases, including their partitioning coefficients; Quantification of the hydrogeological factors (e.g., in situ permeability, conductivity, and storage capacity of each soil and rock type; depth of saturated zone; hydraulic and pressure gradients); The routes of groundwater migration, transport rates, and receptors. Also specifically determine the locations, flow rates, contaminant concentrations, and variability for discharge to bodies of surface water; The seasonal fluctuations in the water table, flow gradients, and contaminant concentrations, simultaneously with other factors such as precipitation, run-off, and stream flow; The condition of existing monitoring wells and the need to replace them or a portion of their installation materials; The construction, location, and proximity, of residential, municipal, and previously installed monitoring wells; The populations and environments at risk; The extent to which the hazardous substances will migrate once the limits of plumes are determined (if modeling studies are involved, the parameters, assumptions, accuracy, contingencies of the studies must be explicitly stated, and a plan established to verify the modeling if a significant risk is indicated for a specific population or environment); A review and illustration of groundwater classifications (the need for institutional controls on ground-water use, considering such controls as adjuncts to remedial action, must be assessed); All physical and chemical waste characteristics that may affect the possible type of treatment (this information must be reported in a chart for each detected compound); FOR W.R. GRACE & Co. - CONN. M \WP_DOCS\N099\2000M20I0820 WPD 2"2 HSI GGOTTSflS, IDC. • The potential risks associated with future releases resulting from onsite residuals; and • The background levels for groundwater quality at a sufficient number of horizontal and vertical locations, including unconsolidated overburden and bedrock. Section 1 of this report evaluated all historic groundwater and surface water data collected in the area northeast of the Grace property. Section 1 identified several areas requiring further investigation including: the direction of groundwater flow and the quality of groundwater north of the Airco Industrial site; • th directioe n of groundwater flow and the quality of groundwater west of the Airco Industrial site and north of the Grace property. Specific activities designed to address these areas are described below. Investigations proposed in this Addendum will be done using the same methodologies described in the Project Operations Plan (POP) (HSI GeoTrans, 1999b) submitted in conjunction with the RI Work Plan and modified in the Response to July 13, 1999 Government Party Comments on the Phase 1 Remedial Investigation Work Plan (HSI GeoTrans, 1999c). The changes to the POP that will be made as a result of the additional monitoring locations proposed in this Addendum are described in Appendix B of this document. 2.2.1 MONITORING WELL INSTALLATION The direction of groundwater flow and the quality of groundwater in the area west and north of the Airco Industrial site is not well characterized. Figure 2-2 shows the known extent of groundwater containing VDC concentrations greater than 1 ug/L in 1999 and illustrates that additional data needs to be collected west and north of the Airco Industrial site to further define the extent of VDC contamination. As was discussed in Section 1.4, groundwater containing VDC is found mainly in the deep unconsolidated deposits and bedrock. FOR W R GRACE & Co - CONN M\WP_DOCSN<»<>uooo>12oio82o»TD 2-3 HSI GeoTrans, inc. Limited monitoring points exist in the area north of the Airco Industrial site. While most of the MW series wells on the Airco Industrial site remain intact, few of the PS wells remain. A site reconnaissance conducted in the fall of 1999 by HSI GeoTrans and personnel from the Water Supply District of Acton located the PS-22 and PS-29 clusters and the seven OW series wells. It is assumed that the other PS series wells no longer exist. Six monitoring well clusters will be installed in the area west and north of the Airco Industrial site. The proposed locations of the monitoring well clusters are shown on Figure 2-3. Final monitoring well locations may change due to physical accessibility or if permission to place wells in the selected locations cannot be obtained. One of the monitoring well clusters (AR-26) was originally proposed in Section 3.2.1 of the RI Work Plan. The AR-26, AR-27, AR-28 and AR-29 clusters will be installed to better understand the flow of groundwater and the distribution of groundwater contaminants west and north of the Airco Industrial site. The AR-27 and AR-28 clusters will also be used to evaluate the potential for contaminated groundwater to discharge to Fort Pond Brook. The AR-30 cluster will be installed to evaluate the potential for the Christofferson well to have drawn groundwater contamination under Fort Pond Brook. The location for the sixth well, AR-31, will be determined after reviewing the screening results from the first five clusters. Each cluster will contain a shallow unconsolidated deposits well, a deep unconsolidated deposits well, a shallow bedrock well and a deep bedrock well. The wells will be completed using the methods described in the Response to July 13, 1999 Government Party Comments on the Phase 1 Remedial Investigation Work Plan (HSI GeoTrans, 1999b). Completion intervals for the unconsolidated deposits wells will be selected based on the VDC/benzene concentrations of the soil headspace. the permeability of the geologic material and the depth of the boring. For example, a shallow unconsolidated deposits well will be screened in the upper portion of the saturated unconsolidated deposits in a zone containing the highest VDC/benzene concentrations and more permeable geologic material. Completion intervals for the bedrock wells will be selected based on the VDC/benzene screening results of groundwater samples. After coring 20 feet into bedrock, a groundwater sample will be FOR W.R. GRACE & Co. - CONN. ~~~ \ M \WP_DOCS\N099\2000\I20I0820WPD 2~4 Hoi (jGO I CSPS, IDC. collected and screened in the field for benzene and VDC. Coring and sampling will continue every 20 feet until the field screening indicates low concentrations of benzene and VDC are present in the groundwater. One bedrock well will be completed in the zone containing low concentrations of benzene and VDC to permit monitoring of the bottom of the plume. One bedrock well will be completed in the zone containing the highest concentrations of benzene and VDC to permit monitoring of the plume itself. If low concentrations of benzene and VDC are found in the upper 20 feet of bedrock, drilling will stop and only a shallow bedrock well will be installed. The new monitoring wells will be included as part of the Site-wide water level measurement round and Site-wide groundwater sampling round described in Sections 3.2.5 and 3.2.6 of the RI Work Plan. Groundwater from the new monitoring wells will be analyzed for VOCs and inorganic compounds. 2.2.2 MISCELLANEOUS ACTIVITIES As described in the RI Work Plan, some soil and groundwater samples will be collected to satisfy critical data requirements needed to properly screen and evaluate potential remedial alternatives and technologies. Similar samples will be collected from the area northeast of the Grace property. These include: • total organic carbon (TOC) samples from each unconsolidated deposits geologic unit encountered during the installation of select new wells, and • groundwater screening parameters to evaluate natural attenuation from select wells associated with the northeast plume. The TOC samples will be used to evaluate partitioning of contamination between groundwater, soil and vapors (where applicable). The groundwater screening parameters will be used to assess the likelihood that biodegradation is occurring. Additional details regarding the usefulness of these analyses is included in Section 3.2.9 of the RI Work Plan. The POP outlines how these data will be collected and analyzed. FOR W R GRACE & Co - CONN ~ ~ M \WP_DOCS\NOW2000\I2010820WPD 2-5 HSI GGOTfaHS, IPC. 2.3 SURFACE WATER AND SEDIMENTS The SOW requires that the nature and extent of contamination from the Site to surface water bodies be determined. More specifically, evaluations are to include: • groundwater migration releases to surface water and • th extene t to which contamination from the Site has affected or threatens to affect human health and the environment. Fort Pond Brook, described in Sections 1.3.2.4 and 1.5, is located northeast of the Grace property. At this time however, it is not known if groundwater contamination from the Grace property extends as far as Fort Pond Brook in this area. Therefore, no sampling is proposed to be done in Fort Pond Brook. Sampling of Fort Pond Brook will be proposed if data collected during the Phase 1 RI indicates that contaminated groundwater is discharging to Fort Pond Brook. 2.4 LONG-TERM MONITORING Monitoring of groundwater, and potentially surface water and sediment, is required to determine the long-term changes in the nature, extent, quantity, seasonal variability, climatological influence, environmental fate and transport, background levels, and migration pathways for each contaminant at the Site. Based on the results of the Phase 1 RI, long-term monitoring for the area northeast of the Grace property will be evaluated, along with the rest of the Site, as described in Section 3.4 of the RI Work Plan. 2.5 TREATABILITY AND PILOT STUDIES As described in Section 3.5 of the RI Work Plan, no treatability or pilot studies are proposed for the Phase 1 investigations since the narrowing of treatment alternatives based on the Phase 1 investigation results is likely. FOR W.R. GRACE & Co. - CONN. M \wp_Docs\N099V2ooo\i2oios2owpD 2-6 HSI GsoTrsos, inc. rxtt EXISTING TOPOGRAPHI: C 7\-^x * VV Originals Figure 2-1 Proposed Exfenf/on of the Topographic Mop GEOTBANS CHRSTOFFEMON dCraBNEn T EXPLANATION f MONITORING WELL (SINGLE OR CLUSTER) *'• EXTRACTION WELL. 9 WATER SUPPLY WEL _. APPROXIMATE ZONE OF CAPTURE VDC DATA 1999 £^ 100 1 000 ug/L VDC £^j 10 IOC ug/L VDC J^^ 1- 10 UQ/L VOC SITE FEATURES \s 1 INDU^BIAL LANDFILL > 2 FORMER SECONDARY LAGOON • * MUSKRAT O FORMER ACID NUTRALJZATIQN PIT TURTLE POND ^ FORMER BLCWDOWN PIT 5 FORMER EMERGENCY LAGOON POND 6 FORMER PRIMARY LAGOON 7 FORMER BATTER> SEPARATOR AREA 8 FORMER NORTH OGQON 9 FORMER TANK CAR AREA ASSABET I* BASE MAT GOMFUD ntOM nKFtao r* C#WP wtsa AU LOCA10NS Original includes color coding. HSI OEOTDANS Figure 2-2 Schematic of 1999 VDC Concentrations in Udundwater A TETIA TKCH CBHPAHV sch-vdc99 dwg WEI,. LOCATIONS W R GRACE PROPERTY FROM INFORMATION PROVIDED BY CAMP PERTY LINE LOCATIONS ARE FROM SORS MAPS INFORMATION m THE QUAD AND FROM fNFORMATION BY PINE ^PROXIMATE AR-26 • PROPOSED UONITORING HELL V™"\> KR GRACE PROPtRTY UNE (APPROX) SURROUMOMG PHOPERTr UNE (APPROX.) ASSESSOR'S PROPERTY NUMBER EXTRACTION MIL PUBLIC WATER SUPPLY HELL PROPOSED PUBLIC WATER SUPPLY WELL Site Map with Proposed Sampling Locations W.R. Grace, Acton, MA. HSI MJriginal incjjkdes color coding. GEOTDANS 3 REFERENCES Barosh, Patrick, J. Richard J. Fahey and M.H. Pease, Jr., 1977, Preliminary Compilation of the Bedrock Geology of the Land Area of Boston 2° Sheet, Massachusetts, Connecticut, Rhode Island and New Hampshire, USGS Open-File Report 77-285. Dufresne-Henry, Inc., 1981, Report on Continuous Pumping Test, Lawsbrook Wellfield, 4/81. Dufresne-Henry, Inc., 1996, Report on Water System Master Plan Update, Acton Water District, Acton, MA, 2/96. Goldberg-Zoino & Associates, Inc., 1984, Final Report, Municipal Aquifer Study, Acton, Massachusetts, 6/84. Goldberg-Zoino & Associates, Inc., 1985, Lawsbrook Aquifer Contamination Study, 3/85. Goldberg-Zoino & Associates, Inc., 1989, Final Report, Aquifer Protection Zones, 2/89. Hansen, Wallace R., 1956, Geology and Mineral Resources of the Hudson and Maynard Quadrangle Massachusetts, United States Geological Survey Bulletin 1038. HSI GeoTrans, 1998, Initial Site Characterization Report, Operable Unit Three, 8/12/98. HSI GeoTrans, 1999, Phase 1 Remedial Investigation Work Plan, 5/14/99. HSI GeoTrans, 1999, Project Operations Plan, 5/14/99. HSI GeoTrans, 1999, Response to July 13, 1999 Government Party Comments on the Phase 1 Remedial Investigation Work Plan, 11/12/99. National Oceanic and Atmospheric Administration (NOAA), 1997, Climatological Data Annual Summary, New England, Bedford, Massachusetts Station. Pine and Swallow Associates, 1986, Reconnaissance Contaminant Hydrology, Southern Lawsbrook Aquifer, Acton, Massachusetts, 5/86. Pollock, S.J., Farrell, D.F., and Caswell, W.W., 1969, Water Resources of the Assabet River Basin Central Massachusetts, USGS HA-312. FOR W.R. GRACE & Co. - CONN. M \WP_DOCS\N099\2000M20I0820WPD 3~1 HSI GSOlrSflS, IHC. TARGET SHEET THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE: (X) OVERSIZED MAP () NON-PAPER MEDIA () OTHER: DOCK): 43194 DATE: January 14, 2000 TITLE: Addendum to the Phase 1 Remedial Investigation Work Plan DESCRIPTION: Figure 3-1: Topographic Site Map THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER, BOSTON, MA APPENDIX A WATER QUALITY SUMMARY TABLES FOR W.R. GRACE & Co. - CONN. M*WP_DOCS\N099\2000M2010820W]>D HSI GGOI PSHS, IDC. Table A-l. Summary of compounds detected prior to 1999 northeast of the Grace Property (MW and PS series wells, Christofferson, Lawsbrook and Scribner wells), (sorted by location) Minimum Maximum Average No. Samples with Concentration Concentration Concentration Detections / Total Location Compound (ue/l) (ue/D (ue/H No. Samples Christofferson 1,1,1 -TRICHLOROETHANE 0.0 1 6 04 11 / 13 1 ,1 -DICHLOROETHANE 00 03 01 4 / 6 1 ,1 -DICHLOROETHENE 00 1 0 02 17 / 18 1,2 -DICHLOROETHENE (TOTAL) trace trace trace 1 / 1 BENZENE trace trace trace 1 / 3 BIS (2-FTHY1 HFXYL) PH FHALATE 300 300 300 I / 1 CHlOROrORM trace trace trace 1 / 3 TRICHLOROETHENE 00 02 0 1 14 / 18 Lawsbrook 1,1,1 -TRICHLOROETHANE 00 35 09 10 / 14 1,1 -DICHLOROETHANE 00 04 0 2 3 / 6 1 , 1 -DICHLOROETHENE 00 68 1 7 16 / 19 BENZENE trace trace trace 1 / 5 BROMODICHLOROMETHANE trace trace trace 1 / 3 CHLOROFORM 14 3 2 24 3 / 3 ISOPROPYL ETHER 33 33 33 1 / 1 METHYL t-BUTYL ETHER 00 05 03 1 / 2 TRICHLOROETHENE 00 04 0 1 15 / 19 MW-11S 1,1,1 -TRICHLOROETHANE 00 2 0 — 0 7 1 / 3 MW-13B 1,1 -DICHLOROETHENE 540 1800 997 3 / 3 BENZENE 00 20 07 1 / 3 VINYL CHLORIDE 20 140 64 3 / 3 MW-16B 1,1 -DICHLOROETHENE 00 20 10 1 / 2 TOLUENE 00 10 05 1 / 2 MW-1B 1,1 -DICHLOROETHENE 00 122 65 5 / 6 For W.R. Grace - Acton Page 1 of 6 HSI GeoTrans, inc. P \pn>J«t\wrg»cton\ac«ss97\N099db mdb RPT CombinedSlats new Friday, January 14, 2000 Table A-l. (continued) Minimum Maximum Average No. Samples with Concentration Concentration Concentration Detections / Total Location Comnound (ue/T) rue/n fue/n No. Samples BKN/l-NI 0.0 4 0 1.2 3 / 6 BIS (2-ETHYLHEXYL) PHTHALATE 0.0 580 19.0 3 / 5 TOLUENE 0.0 3.0 0.9 2 / 6 VINYL CHLORIDE 0.0 2.8 0.5 1 / 6 MW-2B 1,1-DICHLOROETHENE 0.0 3.0 0.4 1 / 7 BIS (2-ETHYLHEXYL) PHTHALATE 0.0 85.0 19.0 2 / 5 TOLUENE 0.0 2.2 0.3 1 / 7 MW-2D BENZENE 0.0 1.0 0.3 1 / 3 BIS (2-ETHYLHEXYL) PHTHALATE 0.0 4.0 1.3 1 / 3 TOLUENE 0.0 2.0 0.7 1 / 3 TRICHLOROETHENE 0.0 3.0 1.0 1 / 3 MW-2S BIS (2-ETHYLHEXYL) PHTHALATE 0.0 50.0 16.7 1 / 3 MW-3B BIS (2-ETHYLHEXYL) PHTHALATE 31.0 31.0 31.0 1 / 1 TOLUENE 1.2 1.2 1.2 1 / 1 MW-3D BIS (2-ETHYLHEXYL) PHTHALATE 0.0 8.0 1.6 1 / 5 MW-4B 1,1-DICHLOROETHENE 0.0 114.0 62.0 5 / 6 BENZENE 0.0 3.0 1.4 4 / 6 TOLUENE 0.0 2.9 0.8 2 / 6 VINYL CHLORIDE 0.0 12.0 4.0 4 / 6 MW-4D 1,1,1 -TRICHLOROETHANE 0.0 2.0 1.0 4 / 6 BIS (2-ETHYLHEXYL) PHTHALATE 0.0 4.2 0.8 1 / 5 TRICHLOROETHENE 0.0 1.2 0.4 2 / 6 MW-4S TOLUENE 0.0 1.6 0.2 1 / 7 MW-5S For W.R. Grace - Acton Page 2 of 6 HSI GeoTrans, inc. P \projecl\wrgaclon\acc<:ss97\N099db mdb - RPT CombmedSuts-new Friday, January 14, 2000 Maximum Average No. Samples with ^^^^^^P^^^^ Minimum ^^BP^^ Concentration Concentration Concentration Detections / Total •PPEound fUB/fi fue/n fua/n No. Samples 1 , 1 ,1 -TRICHLOROETHANE 0.0 30 1 6 4 / 5 BIS (2-ETHYLHEXYL) PHTHALATE 0.0 3.0 06 1 / 5 MW-6B 1,1-DICHLOROETHENE 290.0 810.0 556.2 6 / 6 BENZENE 0.0 2.8 0.8 2 / 6 BIS (2-ETHYLHEXYL) PHTHALATE 0.0 1 9 0.5 1 / 4 VINYL CHLORIDE 0.0 35.0 17.9 5 / 6 MW-6D BIS (2-ETHYLHEXYL) PHTHALATE 0.0 11.0 2.8 1 / 4 TRJCHLOROETHENE 0.0 1.9 0.3 1 / 6 MW-6S 1,1,1 -TRICHLOROETHANE 0.0 3.8 1.4 4 / 5 BIS (2-ETHYLHEXYL) PHTHALATE 0.0 49.0 12.3 1 / 4 TRICHLOROETHENE 0.0 1.0 0.3 2 / 5 MW-7B 1 ,1 -DICHLOROETHENE 71.0 250.0 133.3 3 / 3 BENZENE 0.0 6.8 3.3 2 / 3 TOLUENE 0.0 6.0 2.0 1 / 3 VINYL CHLORIDE 2.0 430 17.7 3 / 3 MW-7S 1,1,1 -TRICHLOROETHANE 0.0 49 1.1 2 / 8 BIS (2-ETHYLHEXYL) PHTHALATE 0.0 33.0 5.5 1 / 6 PS-20 1,1-DICHLOROETHENE 29.0 29.0 29.0 1 / 1 TRICHLOROETHENE 0.3 0.3 0.3 1 / 1 PS-21A 1 ,1 -DICHLOROETHENE 0.0 06 0.4 2 / 3 TRICHLOROETHENE trace trace trace 2 / 2 PS-21B 1,1,1 -TRICHLOROETHANE 11.2 11.2 11.2 1 / 1 1 , 1 -DICHLOROETHENE 3.3 3.3 3.3 1 / 1 TETRACHLOROETHENE 0.0 0.0 0.0 1 / 1 For W.R. Grace - Acton Page 3 of 6 HSI GeoTrans, inc. P \project\wrgicton\icciti97\N099db.mdb - RPT.CoobinedStiti-iww Friday, January 14, 2000 Table A-l. (continued) Minimum Maximum Average No. Samples with Concentration Concentration Concentration Detections / Total Location Compound (ue/n fue/U (ue/n No. Samples TR1CHLOROETHENE 06 06 06 i / i PS-22A 1,1-DICHLOROETHENE trace trace trace i / i TRLCHlOROEFHLNh trace trace trace i / i PS-22B 1,1-DICHLOROETHENE 170 170 170 i / i TRICHLOROETHENE 0.9 09 09 i / i PS-23 TR1CHLOROETHENE trace trace trace i / i PS-24 TETRACHLOROETHENE trace trace trace i / i TRICHLOROETHENE trace trace trace i / i PS-25A TETRACHLOROETHENE trace trace trace i / i TRICHLOROETHENE trace trace trace i / i PS-25B TETRACHLOROETHENE trace trace trace i / i TRICHLOROETHENE trace trace trace i / i PS-26A 1,1,1 -TRJCHLOROETHANE 5.4 61 58 2 / 2 1 ,1 -DICHLOROETHENE 0.2 02 0.2 1 / 1 TETRACHLOROETHENE 0.0 1 3 06 1 / 2 TRICHLOROETHENE 00 1 4 07 1 / 2 PS-26B 1,1-DICHLOROETHENE 30 45 38 2 / 2 BENZENE 1 8 20 1 9 2 / 2 TETRACHLOROETHENE 0.2 02 02 1 / I TRICHLOROETHENE 20 26 23 2 / 2 PS-27A TETRACHLOROETHENE 08 08 08 1 / 1 TR1CHLOROETHENE trace tratc- trace 1 / 1 PS-27B For W.R. Grace - Acton Page 4 of 6 HSI GeoTrans, inc. P \project\wrgKton\uxess97\N099db mdb - RJ>T CombmedStals-ww Friday, January 14, 2000 Table A-l. (continued) Minimum Maximum Average No. Samples with Concentration Concentratio n Concentration Detections / Total Location Comnound (uti/n No. Samples TETRACHLOROETHENE O.I 0.1 0.1 i / 1 TOLUENE 0.1 0.1 0.1 i / 1 TRICHLOROETHENE 0.1 O.I O.I i / 1 PS-29A 1,1,1 -TRICHLOROETHANE 6.7 6.7 6.7 2 / 2 1,1-DICHLOROETHENE 0.0 0.3 0.2 1 / 2 TETRACHLOROETHENE 0.3 0.3 0.3 1 / 1 TRICHLOROETHENE 0.0 0.6 0.3 1 / 2 PS-29B 1,1,1 -TRICHLOROETHANE 8.2 11.6 9.9 2 / 2 1,1-DICHLOROETHENE 6.2 9.7 79 2 / 2 BENZENE 1.9 2.4 2.2 2 / 2 TETRACHLOROETHENE 0.0 1.4 0.7 1 / 2 TRICHLOROETHENE 1.2 2.2 1.7 2 / 2 PS-30A 1,1,1 -TRICHLOROETHANE 2.8 2.8 2.8 1 / 1 1,1-DICHLOROETHENE trace trace trace I / I TRICHLOROETHENE trace trace trace 1 / 1 PS-30B 1,1,1 -TRICHLOROETHANE 46.5 46.5 46.5 1 / 1 1,1 -DICHLOROETHENE 8.0 8.0 8.0 1 / 1 cis-l,2-DICHLOROETHENE 0.3 0.3 0.3 1 / 1 TETRACHLOROETHENE 3.2 3.2 3.2 1 / 1 TRICHLOROETHENE 4.0 4.0 4.0 1 / 1 PS-31A 1,1-DICHLOROETHENE 0.2 0.2 0.2 1 / 1 PS-31B 1,1-DICHLOROETHENE 154.0 154.0 154.0 1 / 1 PS-32A 1,1,1 -TRICHLOROETHANE 14.0 14.0 14.0 1 / 1 1,1-DICHLOROETHENE 0.1 0 1 0.1 1 / 1 TETRACHLOROETHENE 1.0 1.0 1.0 1 / 1 For W.R. Grace - Acton Page 5 of 6 HSI GeoTrans, inc. P \projecl\wrgacton\acccss97\N099db mdb - RPT CornbrnedStals-new Friday, January 14, 2000 able A-l. (continued) Minimum Maximum Average No. Samples with Concentration Concentration Concentration Detections / Total Location Comnound rue/n rue/1) fue/1) No. Samnles TRICHLOROETHENE 1.6 1 6 1.6 i / 1 PS-32B 1,1,1 -TRICHLOROETHANE 7.5 7.5 7.5 i / 1 1,1 -DICHLOROETHENE 0.1 01 0.1 i / 1 TETRACHLOROETHENE 0.3 0.3 03 i / 1 TRICHLOROETHENE 1.3 13 1.3 i / 1 PS-33 1.1 -DICHLOROETHENE trace trace trace i / 1 PS-34B 1,1 -DICHLOROETHENE 180.0 1800 180.0 i / 1 TRICHLOROETHENE 4.9 49 4.9 i / 1 Scribner 1,1.1 -TRICHLOROETHANE 0.0 32 1.0 17 / 21 1,1 ,2,2-TETRACHLOROETHANE trace trace trace 1 / 3 1 ,1 -DICHLOROETHANE 0.0 03 0 1 2 / 4 1,1 -DICHLOROETHENE 0.0 86 12 21 / 23 CHLOROFORM 0.0 9.7 1.9 3 / 5 TRICHLOROETHENE 0.0 07 0.2 15 / 19 For W.R. Grace - Acton Page 6 of 6 HSI GeoTrans, inc. P Vprojea\wrgaciiM\KceM97\N099db mdb - RPT CombnedSuis-new Friday, January 14,2000 able A-2. Summary of compounds detected prior to 1999 northeast of the Grace Property (MW and PS series wells, Christofferson, Lawsbrook and Scribner wells), (sorted by compound) Minimum Maximum Average No. Samples with Concentration Concentration Concentration Detections / Total Compound Location (ue/\) Tue/l) (ue/h No. Samples BIS a-ETHYLHEXYL> PHTHALATE MW-3B 31 31 31.0 i / 1 Christofferson 30 30 30.0 i / 1 MW-2B 0 85 19.0 2 / 5 MW-IB 0 58 19.0 3 / 5 MW-2S 0 50 16.7 1 / 3 MW-6S 0 49 12.3 1 / 4 MW-7S 0 33 5.5 / 6 MW-6D 0 11 2.8 / 4 MW-3D 0 8 1.6 / 5 MW-2D 0 4 1.3 / 3 MW-4D 0 4.2 0.8 / 5 MW-5S 0 3 0.6 / 5 MW-6B 0 1.9 0.5 / 4 1.1.1-TRICHLOROETHANE PS-30B 46.5 46.5 46.5 / 1 PS-32A 14 14 14.0 / 1 PS-21B 11.2 11.2 11.2 / 1 PS-29B 8.2 11.6 9.9 2 / 2 PS-32B 7.5 7.5 7.5 1 / 1 PS-29A 6.7 6.7 6.7 2 / 2 PS-26A 5.4 6.1 5.8 2 / 2 PS-30A 2.8 2.8 2.8 1 / I MW-5S 0 3 .6 4 / 5 MW-6S 0 3.8 .4 4 / 5 MW-7S 0 4.9 .1 2 / 8 MW-4D 0 2 .0 4 / 6 Scribner 0 3.2 .0 17 / 21 Lawsbrook 0 3.5 0.9 10 / 14 MW-11S 0 2 0.7 1 / 3 For W.R. Grace - Acton Page 1 of 5 HSI GeoTrans, inc. P \prqjecl\wrg«cton'UKcess97\N099db mdb - RPT_COMBINEDSTATSBYCHEM-new Table A-2. (continued) Minimum Maximum Average No. Samples with Concentration Concentration Concentration Detections / Total Compound Location fug/1) fueW (U2/l» No. Samples Christofferson 0 1.6 0.4 11 / 13 1 .1 .2.2-TETRACHLOROETHANE Scribner trace trace trace 1 / 3 1.1-DICHLOROETHANE Lawsbrook 0 0.4 0.2 3 / 6 Christofferson 0 0.29 O.I 4 / 6 Scribner 0 0.32 O.I 2 / 4 1.1-DICHLOROETHENE MW-6B 290 810 556.2 6 / 6 PS-34B ISO 180 180.0 1 / 1 PS-31B 154 154 154.0 1 / I MW-7B 71 250 133.3 3 / 3 MW-13B 54 180 99.7 3 / 3 MW-4B 0 114 62.0 5 / 6 PS-20 29 29 29.0 1 / 1 PS-22B 17 17 17.0 1 / 1 PS-30B 8 8 8.0 1 / 1 PS-29B 6.2 9.7 7.9 2 / 2 MW-1B 0 12.2 6.5 5 / 6 PS-26B 3 4.5 3.8 2 / 2 PS-21B 3.3 3.3 3.3 1 / 1 Lawsbrook 0 6.8 1.7 16 / 19 Scribner 0 8.6 1.2 21 / 23 MW-16B 0 2 1.0 1 / 2 MW-2B 0 3 0.4 I / 7 PS-21A 0 0.58 0.4 2 / 3 PS-31A 0.21 0.21 0.2 1 / 1 Christofferson 0 1 0.2 17 / 18 PS-29A 0 0.32 0.2 1 / 2 PS-26A 016 0 16 02 1 / 1 PS-32A 0.11 0 11 0.1 I / I PS-32B 0.1 0.1 0.1 1 / 1 For W.R. Grace - Acton Page 2 of 5 HSI GeoTrans, inc. P \prpjecl\wrgacton\accMs97\N099d6 mdb - RPT COMBINEDSTATSBYCHEM-new Friday, January 14, 2000 L ^^^^••P' Minimum Maximum Average No. Samples with ^^^^H^^^ Concentration Concentration Concentration Detections / Total ^^^^^ompound Location fue/l) fue/h rue/1) No. Samples P""" PS-22A trace trace trace i / 1 PS-33 trace trace trace i / 1 PS-30A trace trace trace i / 1 1.2-DICHLOROETHENE (TOTALS Christofferson trace trace trace i / 1 BENZENE MW-7B 0 6.8 3.3 2 / 3 PS-29B 1.9 2.4 2.2 2 / 2 PS-26B 1.8 2 1.9 2 / 2 MW-4B 0 3 1.4 4 / 6 MW-1B 0 4 1.2 3 / 6 MW-6B 0 2.8 0.8 2 / 6 MW-13B 0 2 0.7 1 / 3 MW-2D 0 1 0.3 1 / 3 Lawsbrook trace trace trace 1 / 5 Christofferson trace trace trace 1 / 3 BROMODICHLOROMETHANE Lawsbrook trace trace trace 1 / 3 CHLOROFORM Lawsbrook 1.4 3.2 2.4 3 / 3 Scribner 0 9 7 1.9 3 / 5 Christofferson trace trace trace 1 / 3 cis-1 .2-DICHLOROETHENE PS-30B 0.33 0.33 0.3 1 / 1 ISOPROPYL ETHER Lawsbrook 3.3 3.3 3.3 1 / 1 METHYL t-BUTYL ETHER LAWSBROOK 0 0.5 0.3 1 / 2 TETRACHLOROETHENE PS-30B 3.2 3.2 3.2 1 / 1 PS-32A 1 1 1.0 1 / 1 PS-27A 0.84 0.84 0.8 1 / 1 For W.R. Grace - Acton Page 3 of 5 HSI GeoTrans, inc. P.\projed\wg»cton\K«u97\N099db mdb - RPT_COMBINEDSTATSBYCHEM-new Friday, January 14, 2000 Table A-2. (continued) Minimum Maximum Average No. Samples with Concentration Concentration Concentration Detections / Total Compound Location fue/n fug/]) fue/1) No. Samples PS-29B 0 1.4 07 1 / 2 PS-26A 0 1.3 0.6 1 / 2 PS-29A 0.33 0.33 0.3 1 / PS-32B 0.29 0.29 0.3 1 / PS-26B 0.2 02 0.2 1 / PS-27B 0.11 0.11 0.1 1 / PS-21B 0.03 0.03 00 1 / PS-25A trace trace trace 1 / PS-24 trace trace trace 1 / 1 PS-25B trace trace trace 1 / 1 TOLUENE MW-7B 0 6 20 1 / 3 MW-3B 1.2 1.2 1.2 1 / 1 MW-1B 0 3 0.9 2 / 6 MW-4B 0 29 08 2 / 6 MW-2D 0 2 0 7 1 / 3 MW-16B 0 1 0.5 1 / 2 MW-2B 0 2.2 03 1 / 7 MW-4S 0 16 02 1 / 7 PS-27B 0.12 0.12 0 1 1 / 1 TRICHLOROETHENE PS-34B 4.9 49 49 1 / 1 PS-30B 4 4 4.0 1 / 1 PS-26B 2 26 2.3 2 / 2 PS-29B 1.2 2 2 17 2 / 2 PS-32A 1.6 1.6 1.6 1 / 1 PS-32B 1.3 1.3 1.3 1 / 1 MW-2D 0 3 1.0 1 / 3 PS-22B 0.87 0.87 0.9 1 / 1 PS-26A 0 1.4 0.7 1 / 2 PS-21B 0.57 0.57 06 1 / 1 MW-4D 0 1.2 0.4 2 / 6 For W.R. Grace - Acton Page 4 of 5 HSI GeoTrans, inc. P \prpiectWgicton\icces597\N099db mdb - RPT COMBINEDSTATSBYCHEM-new Friday, January 14, 2000 Minimum Maximum Average No. Samples with Concentration Concentration Concentration Detections / Total ^r Compound Location fue/n fue/n fu2/n No. Samples PS-20 0.34 0.34 0.3 i / 1 MW-6S 0 1 0.3 2 / 5 MW-6D 0 1.9 0.3 1 / 6 PS-29A 0 0.63 0.3 1 / 2 Scribner 0 0.66 0.2 15 / 19 PS-27B 0.12 0.12 0.1 1 / 1 Lawsbrook 0 0.41 0.1 15 / 19 Christofferson 0 0.18 0.1 14 / 18 PS-23 trace trace trace / PS-30A trace trace trace / PS-27A trace trace trace / PS-22A trace trace trace / PS-25A trace trace trace / PS-25B trace trace trace / PS-21A trace trace trace 2 / 2 PS-24 trace trace trace |/ 1 VINYL CHLORIDE MW-6B 0 35 17.9 5 / 6 MW-7B 2 43 17.7 3 / 3 MW-13B 2 14 6.4 3 / 3 MW-4B 0 12 4.0 4 / 6 MW-1B 0 2.8 0.5 1 / 6 For W.R. Grace - Acton Page 5 of 5 HSI GeoTrans, inc. P \|iroject\wrgicton\««wi97\N099db mdb - RPT_COMBINEDSTATSBYCHEM-nev» Friday, January 14, 2000 Table A-3. Summary of compounds detected in 1999 northeast of the Grace Property (MW series wells, Christofferson, Lawsbrook and Scribner wells), (sorted by location) Minimum Maximum Average No. Samples with Concentration Concentration Concentration Detections / Total Location Compound (us/I} (ue/n rue/I) No. Samples MW-13B U-D1CHLOROETHENE 320 320 320 i / i BENZENE 38 38 38 i / i VINYL CHLORIDE 170 170 170 i / i MW-1B 1 , 1 -D1CHLOROETHENE 18 18 18 i / i ACETONE 390 390 390 i / i BENZENE 20 20 20 i / i ETHYLBENZENE 05 05 05 i / i MW-4B 1,1 -DICHLOROETHENE 310 310 310 i / i ACETONE 470 470 470 i / i BENZENE 95 95 95 i / i ETHYLBENZENE 10 1 0 1 0 i / i VINYL CHLORIDE 21 2 1 21 i / i MW-4D 1,1,1 -TRICHLOROETHANE 09 09 09 i / i TETRACHLOROETHENE 05 05 05 i / i TRICHLOROETHENE 1 5 1 5 1 5 i / i MW-6B 1,1-DICHLOROETHENE 3000 3000 3000 i / i BENZENE 53 53 53 i / i CHLOROETHANE 10 10 1 0 i / i ETHYLBENZENE 08 08 08 i / i VINYL CHLORIDE 100 100 100 i / i MW-7B 1,1 -DICHLOROETHENE 1600 1600 1600 2 / 2 ACETONE 120 130 125 2 / 2 BENZENE 70 7 2 71 2 / 2 VINYL CHLORIDE 210 210 210 2 / 2 Note Pre-validation results For W.R. Grace - Acton Page 1 of 1 HSI GeoTrans, inc. P\pro)ea\wrgiclon\«cccss97\NEW_ 1 .1 ,1-TRICHLOROETH ANE MW-4D 086 086 09 i / 1 1. 1 -DICHLOROETHENE MW-6B 300 300 3000 i / 1 MW-7B 160 160 1600 2 / 2 MW-13B 32 32 320 1 / 1 MW-4B 31 31 310 1 / 1 MW-IB 18 1 8 1 8 1 / 1 ACETONE MW-4B 47 47 470 1 / 1 MW-IB 39 39 390 1 / 1 MW-7B 12 13 12 5 2 / 2 BENZENE MW-4B 95 95 9 5 1 / 1 MW-7B 7 72 7 1 2 / 2 MW-6B 5 3 53 5 3 1 / 1 MW-13B 3 8 3 8 3 8 1 / 1 MW-IB 2 2 20 1 / 1 CHLOROETHANE MW-6B 1 1 1 0 1 / 1 ETHYLBENZENE MW-4B 098 098 1 0 1 / 1 MW-6B 083 083 08 1 / 1 MW-IB 052 052 05 1 / 1 TETRACHLOROETHENE MW-4D 05 1 051 05 1 / 1 TRICH LOROETHENE MW-4D 1 5 1 5 1 5 1 / 1 VINYL CHLORIDE MW-7B 21 21 21 0 2 / 2 For W.R. Grace - Acton Page 1 of 2 HSI GeoTrans, inc. P \prqiect\wrgicton\access97\NEW_diu mdb • RPT_COMBINEDSTATSB YCHEM-new Friday, January 14, 2000 Table A-4. (continued) Minimum Maximum Average No. Samples with Concentration Concentration Concentration Detections / Total Compound Location (ue/n (ue/N fui!/l) No. Samples MW-I3B 17 17 170 i / i MW-6B 10 10 100 i / i MW-4B 21 2 1 2 1 i / i Note: Pre-validation results For W.R. Grace - Acton Page 2 of 2 HSI GeoTrans, inc. P \projecl\wrgiaon\iccess97\NEW_dau mdb - RPT_COMBINEDSTATSBYCHEM-new Friday, January 14, 2000 APPENDIX B ADDITIONS TO PROJECT OPERATIONS PLAN FOR W.R. GRACE & Co. - CONN. M \WP_DOCS\N099\2000\I 20 1 0820 WTO HSI , IflC. The following changes will be made to the specified sections of the POP as a result of work proposed in the Addendum. Site Management Plan The information on the attached Table B-l and Figure B-l will be added to the corresponding Table 3-1 and Figure 3-1 of the Site Management Plan to account for additional property access that will be necessary. Field Sampling Plan The information on the attached Table B-2 and Figure 2-3 of the Addendum will be added to the corresponding Table 2-1 and Figure 2-1 of the Field Sampling Plan to account for additional water level measurements that will be collected. The information on the attached Table B-3 and Figure 2-3 of the Addendum will be added to the corresponding Table 2-3 and Figure 2-1 of the Field Sampling Plan to account for additional groundwater samples that will be collected. The following text will be added to Section 3 of the Field Sampling Plan to account for the new monitoring wells that will be installed northeast of the Site. Six monitoring well clusters will be installed in the area northeast of the Grace property. Each well cluster will contain a shallow unconsolidated deposits well, a deep unconsolidated deposits well, a shallow bedrock well and a deep bedrock well. The information on the attached Table B-4 and Figure 2-3 of the Addendum will be added to the corresponding Table 3-1 and Figure 2-1 of the Field Sampling Plan to account for additional monitoring wells that will be installed. The information on the attached Table B-5 will be added to the corresponding Table 3-2 of the Field Sampling Plan to account for additional TOC soil samples that will be collected. FOR W.R. GRACE & Co. - CONN. ~~ ~ M \WP_DOCS\N099V2000\120I0820wpo APP-B"1 HSI G6OTr3DS, JPC. Table B-l. Properties for which access may be required MAP# LOT# ^ PROPERTY OWNER MAILING ADDRESS STATUS H-4 76 Acton Water District PO Box 953, Acton, MA Not Established 113 Acton Water District PO Box 953, Acton, MA Not Established 114 Acton Water District PO Box 953, Acton, MA Not Established 116-3 Lawsbrook, Inc. 5 Lawsbrook Road (rear) Not Established 119 Acton Water District PO Box 953, Acton, MA Not Established 126 Acton Water District PO Box 953, Acton, MA Not Established 130 Acton Water District PO Box 953. Acton, MA Not Established 134 Acton Water District PO Box 953, Acton, MA Not Established 135 Acton Water District PO Box 953. Acton, MA Not Established 139-1 Acton Water District PO Box 953, Acton, MA Not Established 143 Air Reduction Company 37 Lawsbrook Road. Acton. MA Established (Airco) 152 Air Reduction Company 37 Lawsbrook Road, Acton, MA Established (Airco) FOR W.R. GRACE & Co. - CONN. M\WP DOCS\N09WOOO\I20I0820WPD APP-B-2 HSI GeoTrans, inc. Table B-2. Site-wide water level monitoring locations LOCATION MW-1B AR-26D AR-31D MW-1D AR-26S AR-31S MW-1S AR-26SBR AR-31SBR MW-2B AR-26DBR AR-31DBR MW-3D AR-27D Christofferson MW-3S AR-27S Lawsbrook MW-4B AR-27SBR Scribner MW-4D AR-27DBR OW-A MW-4S AR-28D OW-B MW-6B AR-28S OW-C MW-6D AR-28SBR OW-D MW-6S AR-28DBR OW-E MW-7B AR-29D OW-8 MW-7D AR-29S OW-F MW-7S AR-29SBR PS-29A MW-8S AR-29DBR PS-29B MW-10S AR-30D PS-22A MW-13B AR-30S PS-22B MW-15S AR-30SBR MW-16B AR-30DBR FoRW.R GRACE & Co. - Com. M\WP DOCS'NC»w:000\]20l0820wvi) APP-B-3 HSI GeoTrans, inc. Table B-3. Groundwater sampling locations and analyses LOCATION VOCs SVOCS INORGANICS NITROGEN/ TOC/TSS NATURAL PHOSPHORUS ATTENUATION MW-1B / V MW-1D / V MW-4B V V MW-4D V V MW-6B V V MW-6D V" V MW-7B / V MW-7D V V MW-13B / V AR-26S V V AR-26D V" V AR-26SBR V V AR-26DBR V V AR-27D V V AR-27S V / AR-27SBR / V AR-27DBR / V AR-28D V V AR-28S V V AR-28SBR / V AR-28DBR V" V AR-29D V / / AR-29S / V AR-29SBR / V / AR-29DBR V V AR-30D V V AR-30S V / AR-30SBR •f / AR-30DBR V / AR-31D V / AR-31S V / AR-31SBR V V AR-31DBR / / Christofferson V / Lawsbrook / / Scribner V V FOR W.R. GR.ACE & Co. - CONN. M\WP DOCS\N099\:OOOM20I0820 WTO APP-B-4 HSI GeoTrans, inc. LOCATION VOCS SVOCs INORGANICS NITROGEN/ TOC/TSS NATURAL PHOSPHORUS ATTENUATION OW-A V V OW-D V / OW-E / V OW-8 V V OW-F V V PS-29A V V PS-29B V V PS-22A V / PS-22B V V FOR W.R. GRACE & Co. - CONN. M\WP DOCS\N099\2000\l2010820wpo APP-B-5 HSI GeoTrans, inc. Table B-4. Proposed additional monitoring well locations WELL IDENTIFIER WELL LOCATION LOCATION OF SCREEN AR-26S Northeastern Area shallow unconsolidated deposits AR-26D Northeastern Area deep unconsolidated deposits AR-26SBR Northeastern Area shallow bedrock AR-26DBR Northeastern Area deep bedrock AR-27S Northeastern Area shallow unconsolidated deposits AR-27D Northeastern Area deep unconsolidated deposits AR-27SBR Northeastern Area shallow bedrock AR-27DBR Northeastern Area deep bedrock AR-28S Northeastern Area shallow unconsolidated deposits AR-28D Northeastern Area deep unconsolidated deposits AR-28SBR Northeastern Area shallow bedrock AR-28DBR Northeastern Area deep bedrock AR-29S Northeastern Area shallow unconsolidated deposits AR-29D Northeastern Area deep unconsolidated deposits AR-29SBR Northeastern Area shallow bedrock AR-29DBR Northeastern Area deep bedrock AR-30S Northeastern Area shallow unconsolidated deposits AR-30D Northeastern Area deep unconsolidated deposits AR-30SBR Northeastern Area shallow bedrock AR-30DBR Northeastern Area deep bedrock AR-31S Northeastern Area shallow unconsolidated deposits AR-31D Northeastern Area deep unconsolidated deposits AR-31SBR Northeastern Area shallow bedrock AR-31DBR Northeastern Area deep bedrock FOR W.R. GRACE & Co. - CONN. M \WP DOCS\N099\2000\ 12010820 WPD APP-B-6 HSI GeoTrans, inc. Table B-5. Soil sampling locations for TOC analysis LOCATION SAMPLES CONTINGENCY LOCATION AR-26 1 till, 1 outwash AR-27 AR-28 1 till, 1 outwash AR-28 AR-30 1 till, 1 outwash None FOR W.R. GRACE & Co. - CONN. M\WP DOCS\N099\2000M20I0820WPD APP-B-7 HSI GeoTrans, inc. NOTE BASE MAP BY COL-EAST 1998 WELL LOCATIONS, W R GRACE PROPERTY LINE & MISC SITE FEATURES COMPILED FROM INFORMATION PROVIDED BY CAMP DRESSER & McKEE SURROUNDING PROPERTY LINE LOCATIONS ARE FROM THE TOWN OF ACTON AND CONCORD ASSESSORS MAPS INFORMATION iN THE NORTH AREA HAS BEEN COMPILED FROM JSGS QUAD AND FROM NFORMATION BY PINE & SWALLOW ALL LOCATIONS ARF APPROXIMATE -N EXPLANATION _ - __ W.R. GRACE PROPERTY LME (APPROX.) SURROUNOWG PROPERTY UNE (APPROX.) ASSESSOR'S PROPERTY NUMBER MOWTORMGWELL (9NGLE OR auSTER) EXTRACTION Ml WATER SUPPLY WELL PROPOSED PUBUC WATER SUPPLY \Bi 1/14/00 Properties for Which Access may be Required W.R. Grace, Acton, MA. CHECKED: AB MS FIGURE: HSI DRAFTED: RMK OEOTDANS RLE: Access.dwg B-1 DATE: 1/4/00