Volume 1 KGS 2020c Area 2 PSCS for PFAS-2.pdf

SEPTEMBER 2020

Prepared for:

U.S. Army Corps of Engineers

New England District

Concord, Massachusetts

Prepared by:

KOMAN Government Solutions, LLC

293 Boston Post Road West, Suite 100

Marlborough, MA 01752

Contract No.: W912WJ-18-C-0011

AREA 2 PRELIMINARY SITE CHARACTERIZATION

SUMMARY

PER- AND POLYFLUOROALKYL SUBSTANCES

(PFAS) REMEDIAL INVESTIGATION

FORMER FORT DEVENS ARMY INSTALLATION, DEVENS, MA

NOTICE

The United States Department of Defense, Department of Army, funded wholly or in part the preparation of this document and work described herein under Contract No. W912WJ-18-C-

0011. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

Area 2 Preliminary Site Characterization Summary

Per- and Polyfluoroalkyl Substances (PFAS) Remedial Investigation

Former Fort Devens Army Installation

Devens, Massachusetts

September 2020

CERTIFICATION:

I hereby certify that the enclosed Report, shown and marked in this submittal, is that proposed to be incorporated with Contract Number W912WJ-18-C-0011. This document was prepared in accordance with the U.S. Army Corps of Engineers (USACE) Scope of Work and is hereby submitted for Government approval.

Reviewed By:

09/11/2020

KGS Project Manager Date

Received By:

USACE Project Manager Date

TABLE OF CONTENTS

Section Page i

1.0 INTRODUCTION ...................................................................................................................... 1-1 INVESTIGATION APPROACH ................................................................................. 1-1 REPORT ORGANIZATION ........................................................................................ 1-2

2.0 FORMER FORT DEVENS SITE LOCATION AND DESCRIPTION .................................. 2-1 PHYSICAL CHARACTERISTICS ............................................................................... 2-1 GEOLOGY ..................................................................................................................... 2-1 REGIONAL HYDROGEOLOGY ................................................................................ 2-3

3.0 AOC 32/43A PRELIMINARY SITE CHARACTERIZATION SUMMARY ....................... 3-1 SITE DESCRIPTION ..................................................................................................... 3-1 FACILITY HISTORY AND UTILITIES ...................................................................... 3-1 REMEDIAL STATUS .................................................................................................... 3-1 PFAS FIELD INVESTIGATION .................................................................................. 3-2

Existing Wells ................................................................................................... 3-2 Surface Water and Sediment .......................................................................... 3-3 DPT Vertical Profiles ....................................................................................... 3-3 DPT Soil Borings .............................................................................................. 3-3 Piezometer Installation.................................................................................... 3-3 Synoptic Water Level Surveys ....................................................................... 3-3

PFAS NATURE AND EXTENT .................................................................................. 3-4 Groundwater .................................................................................................... 3-4 Soil ............................................................................................................... 3-5 Surface Water and Sediment .......................................................................... 3-6

4.0 AOC 76/MACPHERSON WELL PRELIMINARY SITE CHARACTERIZATION

SUMMARY ................................................................................................................................. 4-1

SITE DESCRIPTION ..................................................................................................... 4-1 FACILITY HISTORY AND UTILITIES ...................................................................... 4-1 PFAS FIELD INVESTIGATION .................................................................................. 4-2

Existing Wells ................................................................................................... 4-2 Surface Water and Sediment .......................................................................... 4-2 DPT Vertical Profiles ....................................................................................... 4-2 Soil Borings ....................................................................................................... 4-3 Monitoring Wells and Piezometers ............................................................... 4-3 Synoptic Water Level Event ........................................................................... 4-3 Town of Ayer Waste Water Treatment Plant Outflow ............................... 4-3

NATURE AND EXTENT ............................................................................................. 4-3 Groundwater .................................................................................................... 4-4 Soil ............................................................................................................... 4-5 Surface Water and Sediment .......................................................................... 4-5

5.0 AOC 5 SHELPLEY’S HILL LANDFILL PRELIMINARY SITE CHARACTERIZATION

SUMMARY ................................................................................................................................. 5-1

SITE DESCRIPTION ..................................................................................................... 5-1 SITE HISTORY AND UTILITIES ................................................................................ 5-1 REMEDIAL STATUS .................................................................................................... 5-1 ii

PFAS FIELD INVESTIGATION .................................................................................. 5-2 Existing Wells ................................................................................................... 5-2 Surface Water and Sediment .......................................................................... 5-2 Shepley’s Hill Landfill Treatment Plant ....................................................... 5-2

NATURE AND EXTENT ............................................................................................. 5-2 Groundwater in Overburden ......................................................................... 5-3 Groundwater in Bedrock ................................................................................ 5-3 Surface Water and Sediment .......................................................................... 5-3

6.0 DEVENS CAR WASH WELL ................................................................................................... 6-1

7.0 REFERENCES ............................................................................................................................. 7-1 iii

TABLES

Table 1-1 Select PFAS Criteria

Table 2-1 Bedrock Elevations Table 2-2 Synoptic Water Level Event AOC 32/43A, December 5, 2018 Table 2-3 Synoptic Water Level Event AOC 76 and MacPherson, May 16, 2019 Table 2-4 Synoptic Water Level Event AOC 43G and AOC 76, June 28, 2019 Table 2-5 Synoptic Water Level Event SHL, October 22, 2019 Table 2-6 Synoptic Water Level Event AOC 32/43A, April 29, 2020

Table 3-1 AOC 32/43A Field Activities Table 3-2 AOC 32 Summary of PFAS Exceedances from Vertical Profile Samples Table 3-3 AOC 32 Summary of PFAS Exceedances from Monitoring Wells Table 3-4 AOC 43A Summary of PFAS Exceedances from Vertical Profile Samples Table 3-5 AOC 43A Summary of PFAS Exceedances from Monitoring Wells

Table 4-1 AOC 76/MacPherson Field Activities Table 4-2 AOC 76/MacPherson Summary of PFAS Exceedances from Vertical Profile Samples Table 4-3 AOC 76/MacPherson Summary of PFAS Exceedances from Monitoring Wells Table 4-4 AOC 76 Summary of PFAS Exceedances from Soil Borings

Table 5-1 Shepley’s Hill Landfill Field Activities Table 5-2 Shepley’s Hill Landfill Summary of PFAS Exceedances from Monitoring Wells

Table 6-1 Devens Car Wash Well Field Activities

FIGURES

Figure 1-1 Devens PFAS Remedial Investigation Areas

Figure 2-1 Nashua River Basin Figure 2-2 Surface Water Bodies Figure 2-3 USGS Overburden Geology Figure 2-4 Bedrock Geology Figure 2-5 Bedrock Contours Figure 2-6 Devens Groundwater Figure 2-7 Groundwater Elevation Contours Overburden Wells AOC 32/43A December 2018 Figure 2-8 Groundwater Elevation Contours Bedrock Wells AOC 32/43A December 2018 Figure 2-9 Groundwater Elevation Contours AOC 76 and MacPherson – May 16, 2019 Figure 2-10 Groundwater Elevation Contours AOC 43G and AOC 76 – June 28, 2019 Figure 2-11 Groundwater Elevations October 22, 2019 North Impact Area and Shepley’s Hill

Landfill Figure 2-12 Overburden Groundwater Elevation Contours AOC 32/43A April 29, 2020 Figure 2-13 Bedrock Groundwater Elevation Contours AOC 32/43A April 29, 2020

Figure 3-1 AOC 32/43A 1992 Aerial Imagery Figure 3-2 AOC 32/43A Area Historic Subsurface Features iv

Figure 3-3 AOC 32/43A Area Current Subsurface Features Figure 3-4 AOC 32/43A Field Activities Figure 3-5 AOC 32/43A Groundwater Results Figure 3-6 AOC 32 Field Cross Section Location Map Figure 3-7 AOC 32 Cross Section A-A’ Figure 3-8 AOC 32 Cross Section B-B’ Figure 3-9 AOC 32 Soil Sampling Results Figure 3-10 Area 2 results in Surface Water and Sediment Samples

Figure 4-1 AOC 76 Fire Station Area 1992 Aerial Imagery Figure 4-2 AOC 76 Fire Station Area Historic Subsurface Features Figure 4-3 AOC 76 Area Current Subsurface Features Figure 4-4 AOC 76/MacPherson Area Historic Subsurface Features Figure 4-5 AOC 76/MacPherson Area Current Subsurface Features Figure 4-6 AOC 76/MacPherson Area Field Activities Figure 4-7 AOC 76 Fire Station Area Field Activities Figure 4-8 AOC 76 Fire Station Area Groundwater Results Figure 4-9 AOC 76/MacPherson Well Area Groundwater Results Figure 4-10 AOC 76/MacPherson Area Cross Section Locations Figure 4-11 AOC 76 Cross Section A-A’ Figure 4-12 AOC 76 Cross Section B-B’ Figure 4-13 AOC 76 Cross Section C-C’ Figure 4-14 AOC 76 Cross Section D-D’ Figure 4-15 AOC 76 Fire Station Area Soil Sampling Results

Figure 5-1 Shepley’s Hill Landfill 1992 Aerial Imagery Figure 5-2 Shepley’s Hill Landfill Historic Subsurface Features Figure 5-3 Shepley’s Hill Landfill Current Subsurface Features Figure 5-4 Shepley’s Hill Landfill Field Activities Figure 5-5 Shepley’s Hill Landfill Groundwater Results Figure 5-6 Shepley Hill Area Cross Section Locations Figure 5-7 Shepley’s Landfill Cross Section A-A’ Figure 5-8 Shepley’s Landfill Cross Section B-B’ Figure 5-9 Shepley’s Landfill Cross Section C-C’

Plate 1 Sample Locations Plate 2 Groundwater Results

APPENDICES

Appendix A Monitoring Well Field Sheets Appendix B Synoptic Water Level Event Field Sheets Appendix C Surface Water and Sediment Field Sheets Appendix D Vertical Profiling Field Sheets Appendix E Soil Boring Logs Appendix F Piezometer Construction Logs Appendix G Grain Size Results v

Appendix H Analytical Results

H-1 PFAS in Groundwater at Existing Monitoring Wells

PFAS in Groundwater at Existing Monitoring Wells at AOC 32/43A

PFAS in Groundwater at Existing Monitoring Wells at MacPherson

PFAS in Groundwater at Existing Monitoring Wells at AOC 69W

PFAS in Groundwater at Existing Monitoring Wells at Town of Ayer Sludge Landfill

PFAS in Town of Ayer Waste-Water Treatment Plant Effluent

PFAS in Groundwater at Existing Monitoring Wells at Shepley’s Landfill

PFAS in Groundwater at Devens Car Wash Supply Well

H-2 PFAS in Groundwater at Vertical Profile Locations

PFAS in Groundwater at Vertical Profile Locations at AOC 32/43A

PFAS in Groundwater at Vertical Profile Locations at AOC 76

PFAS in Groundwater at Vertical Profile Locations at MacPherson

H-3 PFAS in Groundwater at Water Supply Wells

PFAS in MacPherson Water Supply Well

PFAS in Town of Shirley Patterson Water Supply Well

PFAS in Town of Shirley Walker Water Supply Well

H-4 PFAS in Surface Water and Sediment and TOC in Sediment

AOC 32 Detention Pond Surface Water and Sediment Results

Willow Brook Surface Water and Sediment Results

Plow Shop Pond Surface Water and Sediment Results

Nonacoicus Surface Water and Sediment Results

H-5 PFAS in Soil

PFAS Results in Soil Samples at AOC 32/43A

PFAS Results in Soil Samples at AOC 76 vi

AFFF aqueous film forming foam

AOC area of contamination

Army U.S. Army

AST above ground storage tank

BERS-Weston BERS-Weston Services JVA, LLC bgs below ground surface

BRAC Base Realignment and Closure

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

DPT direct push technology

DRFTA Devens Reserve Forces Training Area

DQO data quality objectives

DRMO Defense Reuse and Marketing Office

E&E Ecology and Environment, Inc.

EPA U.S. Environmental Protection Agency

FS Feasibility Study

FSP field sampling plan ft feet

GW-1 Massachusetts Contingency Plan Method 1 Groundwater

HLA Harding Lawson Associates

J estimated result

KGS KOMAN Government Solutions, LLC k-spar potassium-spar

LHA lifetime health advisory

LTM long-term monitoring

MassDEP Massachusetts Department of Environmental Protection

MassDevelopment Massachusetts Development and Finance Agency

MCP Massachusetts Contingency Plan

MNA monitored natural attenuation

NAVD88 North America Vertical Datum 1988

NIA North Impact Area ng/L nanograms per liter

PA preliminary assessment

PFDA perfluorodecanoic acid

PFAS per- and polyfluoroalkyl substances

PFHpA perfluoroheptanoic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluoronanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

POL petroleum, oil lubricants

PSCS preliminary site characterization summary

RI Remedial Investigation

ROD Record of Decision

SA study area

SHL Shepley’s Hill Landfill

SI Site Inspection SSSL site-specific screening level

S&W Stone and Webster Environmental Technology and Services

S-1 MCP Method 1 S-1 Soil Category µg/kg micrograms per kilogram

UST underground storage tank

1-1

1.0 INTRODUCTION

KOMAN Government Solutions, LLC (KGS), on behalf of the U.S. Army Corps of Engineers (USACE)

New England District, has prepared this Preliminary Site Characterization Summary (PSCS) for the Per-and Polyfluoroalkyl Substances (together, “PFAS”) Remedial Investigation (RI) at the former Fort Devens

Army Installation (Devens) located in Devens, Massachusetts.

The PSCS summarizes data that have been collected at numerous Areas of Contamination (AOC) identified in the Draft Remedial Investigation Work Plan for Per- and Polyfluoroalkyl Substances (PFAS) (KGS, 2018a) and as shown on Figure 1-1.

To expedite the field investigations, the identified AOCs, Grove Pond wellfield, and MacPherson, Patton, and Shabokin water supply well areas were grouped into three areas (Areas 1, 2, and 3). This PSCS addresses part of Area 2 as indicated below.

Area 2 (partial):

• AOC 32/43A Former Defense Reuse and Marketing Office(DRMO)/Petroleum, Oil, Lubricants

(POL) Storage Area;

• AOC 76 Devens Fire Station;

• MacPherson Well Area; and,

• AOC 5 Shepley’s Hill Landfill (SHL).

The Area 1 PSCS (KGS, 2020) addressed Area 1 and part of Area 2 as indicated below.

Area 1:

• AOC 57 Building 3713 Fuel Oil Spill Site;

• AOC 74 Barnum Road Firefighting Exercise Site;

• AOC 75 Former Building T-1445 Warehouse Fire; and,

• Grove Pond wellfield.

Area 2 (partial):

• AOC 40 Cold Spring Brook Landfill;

• AOC 43G Historical Gas Station G;

• AOC 43J Historical Gas Station J;

• Patton water supply well; and,

• Shabokin water supply well.

A future PSCS submittal will include Area 3.

The PSCS is a summary of site data following completion of the initial field sampling and analysis (EPA, 1988). The intent is to better understand and assess any potential data gaps remaining at the AOCs, and determine additional data gathering activities. The U.S. Army (Army) will prepare a bulleted list of data gaps following discussions at the Base Cleanup Team meetings, which will be used to develop specific

Data Quality Objectives (DQO) for the development of an RI Addendum work plan.

Investigation Approach

The initial field activities for the AOCs covered in this PSCS were detailed in the Draft Remedial

Investigation Work Plan for Per- and Polyfluoroalkyl Substances (PFAS) (KGS, 2018a) and the Area 2

Field Sampling Plan (FSP) Addendum to Remedial Investigation Work Plan for Per- and Polyfluoroalkyl

Substances (PFAS) (KGS, 2018b). The initial activities were planned based on results from the Final Base-

Wide Preliminary Assessment for Evaluation of Perfluoroalkyl Substances (KGS, 2017), the Site Inspection

(SI) Addendum for Additional Per- and Polyfluoroalkyl Substances (PFAS) Sampling at Area of

Contamination (AOC) 76-Devens Fire Department and Long Term Monitoring (LTM) Wells at AOCs 57, 43G, 43J, 32, 43A, 50 and Shepley’s Hill Landfill (SHL) Former Fort Devens Army Installation Devens, Massachusetts (BERS-Weston, 2018a), and the Final Site Inspection Report for Per- and Polyfluoroalkyl

1-2

Substances (PFAS) at Former Fort Devens Army Installation, Devens, MA (BERS-Weston, 2018b).

Knowledge of the sites through previous investigations, operation and maintenance activities, and long-term monitoring activities, which included various groundwater models were also used to plan field activities.

The field work was conducted in an iterative manner. The field work commenced with the work detailed in the Area 2 Field Sampling Plan Addendum to Remedial Investigation Work Plan for Per- and

Polyfluoroalkyl Substances (PFAS) (KGS, 2018b). While executing the field work, analytical data from sampling of existing monitoring wells, groundwater vertical profiling, soil sampling, and surface water and sediment sampling was shared with U.S. Environmental Protection Agency (EPA) and Massachusetts

Department of Environmental Protection (MassDEP) as it was received from the laboratory. The results were discussed with EPA and MassDEP and additional activities, not detailed in the field sampling plan

(FSP), needed to achieve the study goals and DQOs were recommended. The recommendations were developed based on review of the analytical data and understanding of groundwater flow direction based on analysis of field data or review of information from previous field investigations or groundwater flow models. Further activities included additional vertical profiles, soil borings, surface water and sediment sampling, existing monitoring well sampling, installation of piezometers, and synoptic water level surveys.

As additional results were received and reviewed, further work was conducted, which sometimes resulted in numerous phases of field activities at different AOCs. The field work at each AOC is discussed in subsequent sections.

After existing monitoring wells were sampled in Area 1 and Area 2, further sampling of existing monitoring wells was detailed in the Work Plan for Additional Sampling of Existing Wells to Support the PFAS

Remedial Investigation Former Fort Devens Army Installation, Devens, MA (KGS, 2019). This supplemental sampling of existing monitoring wells was intended to provide additional data regarding the nature and extent of PFAS at these sites for the RI and will be used to support evaluation of trends in PFAS concentrations in groundwater over time.

There were minor deviations to the FSPs and FSP addendums related to locations of drilling activities, additions and deletions of locations, or activities at specific locations. As is typical with field investigations, some locations were adjusted based on field conditions (e.g., steep terrain, proximity to wetlands, safety considerations). None of the adjustments to the locations negatively impacted meeting the DQOs. There were no major deviations to the methods detailed in the work plan, FSPs, and FSP addendums.

Report Organization

The site characteristics, general geology, and regional hydrogeology at former Fort Devens are described in Section 2. The results of synoptic water level events conducted in the areas addressed in this report are reported in Section 2 and site-specific groundwater flow conditions are described in the subsequent site-specific sections. Sections 3 through 5 each address a specific area of investigation listed above. The PFAS results related to each area of investigation are discussed in the applicable section. The PFAS results in various media are described in each applicable section with respect to the media-specific criteria (Table 1-

1). Section 6 addresses a sample collected from a well that is currently not associated with any AOC in the

PFAS RI. The field sheets, soil boring logs, piezometer construction logs, and results are presented in appendices.

2-1

2.0 FORMER FORT DEVENS SITE LOCATION AND DESCRIPTION

Devens is located in the towns of Ayer and Shirley in Middlesex County, and the towns of Harvard and

Lancaster in Worcester County, Massachusetts, approximately 35 miles northwest of Boston, Massachusetts. The installation occupied approximately 9,260 acres. Fort Devens was divided into the

North Post, Main Post, and South Post. Route 2 divides the South Post from the Main Post. The Nashua

River runs through the North, Main, and South Posts. The area surrounding Devens is primarily comprised of rural residential properties. Portions of Devens have been redeveloped for commercial/industrial use.

Camp Devens was established in 1917 as a temporary training area for soldiers during World War I. In

1932, the site was named Fort Devens and made a permanent installation with the primary mission of commanding, training, and providing logistical support for non-divisional troop units. Fort Devens was used for a variety of training missions between 1917 and 1990. Pursuant to the Comprehensive

Environmental Response, Compensation, and Liability Act (CERCLA), Fort Devens was placed on the

National Priorities List on November 21, 1989, due to environmental contamination at several sites.

Fort Devens was identified for cessation of operations and closure under Public Law 101-510, the Defense

Base Realignment and Closure (BRAC) Act of 1990, and officially closed in March 1996. As part of the

Devens BRAC program, portions of the property formerly occupied by Devens were retained by the U.S.

Army for reserve forces training and renamed the Devens Reserve Forces Training Area (DRFTA). Areas not retained as part of the DRFTA were transferred to new owners, the Massachusetts Development and

Finance Agency (MassDevelopment), U.S. Department of Labor, U.S. Department of Justice, and the U.S.

Fish and Wildlife Service, for reuse and redevelopment. In 2009, the DRFTA was renamed the U.S. Army

Garrison Fort Devens.

Physical Characteristics

Devens lies within the Nashua River basin. The Nashua River flows north through the former North, Main, and South Posts (Figures 2-1 and 2-2). The Nashua River forms the western installation boundary on the former Main Post. Other notable surface water features include: Grove Pond located north of the Grove

Pond wellfield, Plow Shop Pond located west of Grove Pond, Nonacoicus Brook flowing from Plow Shop

Pond to the Nashua River, Cold Spring Brook located east of AOCs 57, 74, and 75, an unnamed stream located east of AOC 43G, Robbins Pond located east of AOC 43G, Willow Brook flowing north from

Robbins Pond to Nonacoicus Brook, Cold Spring Brook Pond (AOC 40), and Mirror Lake and Little Mirror

Lake located between Patton and Shabokin wells. The specific surface water bodies and their relations to specific areas of investigation are discussed in applicable sections.

The geography of Devens is characterized by undulating glacial terrain. The landforms are products of glacial erosion and deposition on a crystalline bedrock terrain. Terrain at Devens falls generally into three types. The least common is bedrock terrain, where rocks that have been resistant to both glacial and fluvial erosion remain as topographic highs, sometimes thinly veneered by glacial deposits. A more common terrain at Devens consists of tills deposited by glaciers. These landforms often conform to the shape of the underlying bedrock surface. They range from areas of comparatively low topographic relief to elongated hills (drumlins) [Harding Lawson Associates (HLA), 2000].

The most common terrain at Devens was formed by sediment accumulations in glacial-meltwater streams and lakes (glaciofluvial and glaciolacustrine deposits). Other prominent glacial meltwater features are kame and kettle topography present on the former Main Post near Mirror Lake and Little Mirror Lake located between the Patton and Shabokin wells.

Geology

The major glacial units consist of till, deltaic deposits from former glacial Lake Nashua, and deposits from glacial meltwater streams (Figure 2-3). Glacial till at Devens consists of unstratified gravel to silt and typically contains boulders. The till at the site is typically approximately 10 feet thick but is up to 60 feet

2-2 thick in the cores of drumlins. The glacial lake deposits consist chiefly of sand and gravelly sand. Lake bottom deposits consist of sand, silt, and clay. Post-glacial deposits consist of river terrace sands and gravels, fine alluvial sands and silts, as well as peat and silt and sands in swampy areas. Generalized surficial geology by AOC is described below and is based on the 2018 Surficial Materials Map of the Ayer

Quadrangle, Massachusetts (Stone and Stone) that in turn, was based on geologic units mapped by Richard

Jahns in 1953 (Jahns, 1953).

• AOC 32/43A - coarse terrace deposits, chiefly kame terraces, coarse sand and pebble to boulder gravel, with bedrock outcrops and till over shallow bedrock to the east and west, and kame deposits farther to the east, and muck and peat in the wetland to the east.

• MacPherson – river terraces and floodplain silt and sand, terraces due in part to erosion.

• Shepley’s Hill Landfill – primarily coarse sand and pebble to boulder gravel kame-plain or ice-contact deposits, with some swamp deposits chiefly muck and peat, some thin deposits of sand and gravel, some sand and pebble to cobble gravel in terrace and delta-outwash plain deposits, some small chiefly pebble to boulder gravel with some fine to coarse sand kame deposits and near

Nonacoicus Brook some kame deposits of shore and near-shore deposits of glacial Lake Nashua.

• AOC 76 – artificial fill and a mix of thins deposits of sand and gravel, sand and pebble to cobble gravel kame deposits, sand and pebble to cobble gravel terrace and delta-outwash plain deposits, and river terraces and floodplain silt and sand to the north.

Bedrock beneath the portion of Devens covered under this PSCS has been mapped as part of the Preliminary

Bedrock Geologic Map of the Ayer Quadrangle, Massachusetts (Kopera, 2006). Bedrock chiefly consists of low-grade metasedimentary rocks, gneisses, and granites. The principal bedrock units are described below and illustrated on Figure 2-4.

• The Oakdale Formation underlies AOC 76 and the MacPherson well. The formation is described by Kopera as thinly laminated, light tan micaceous quartz-muscovite-ankerite siltstone and quartzite interbedded with thin, dark greenish-grey, chlorite-muscovite-quartz- ankerite phyllite.

At biotite and actinolite grade, consists of fine grained reddish and greenish siltstone granofels.

• The Devens Gneiss Complex underlies AOC 32/43A and SHL and is believed to be of Silurian age.

The unit is described by Kopera as light to medium grey, buff to pink weathering, coarse-grained quartz-potassium-spar (k-spar) biotite granite-gneiss, with subordinate tonalitic and dioritic gneiss near Harvard Center. Biotite content varies locally as much as approximately 15 percent. Sheared to a medium to dark grey fine- to medium-grained S/C mylonite with k-spar porphyroclasts near the Clinton-Newbury fault zone. Intruded by the Ayer Granite.

Other bedrock units beneath or in the general vicinity of Devens and depicted on Figure 2-4 include:

• The Ayer Granite of Silurian age and described by Kopera as light to dark grey, buff weathering, coarse-grained, porphyritic quartz-k-spar biotite granite with distinctive k-spar megacrysts up to 8 centimeters in diameter. Locally foliated, sheared and altered to an augen gneiss and talc-bearing schist near the Clinton-Newbury fault zone. A non-porphyritic phase has been mapped separately northwest of Harvard center.

• The Chelmsford Granite of Devonian age and described by Kopera as white to buff weathering, light grey medium- to coarse-grained feldspar-quartzbiotite granite. Biotite occurs in isolated rusty weathering clots. Commonly contains screens and xenoliths of presumed Berwick formation.

Distinctive quartz veins, up to 2 centimeters in width and several meters in length, are common.

Locally foliated and/or sheared near the Clinton-Newbury fault zone. Also includes a medium grey, buff weathering, fine- to medium-grained quartz-feldspar-muscovite-biotite granite-gneiss, and a

2-3 well-foliated light grey k-spar-quartz-muscovite granite-gneiss near the Clinton-Newbury fault.

Intrudes the Ayer granite and Devens gneiss complex.

• The Berwick Formation of Silurian age and described by Kopera as thinly to massively bedded, light green-grey, fine-grained metamorphosed calcareous siltstone, quartzite, and quartzo-feldspathic granofels. Also contains a fine-grained, massively bedded muscovite-quartz-biotite quartzite and schist containing distinctive 1-millimeter knots of biotite.

• The Tadmuck Brook Schist is possibly of late Proterozoic or early Paleozoic age. The formation is described by Kopera as rusty weathering, sulfidic, quartz-muscovite-biotite with or without sillimanite, andalusite, or staurolite, schist. Metamorphic grade increases from west to east across strike.

The bedrock elevation contours were mapped using data gathered as part of the PFAS RI, previous investigations at Devens, well drilling records available through the Massachusetts Energy &

Environmental Affairs Data Portal (eeaonline.eea.state.ma.us), and Massachusetts Geological Survey

(Figure 2-5, Table 2-1). There is significant relief in bedrock elevations across Devens and the surrounding area. The area shown has bedrock elevations ranging from -49 feet (ft) North America Vertical Datum 1988

(NAVD88) to 408 ft NAVD88.

Regional Hydrogeology

The Nashua River is the eventual discharge locus for surface water and groundwater flow at Devens. The tributaries of the Nashua River at Devens are Nonacoicus Brook and Walker Brook on the former North

Post; Cold Spring Brook (which is a tributary of the Nonacoicus Brook through Grove Pond and Plow Shop

Pond) on the former Main Post (Figure 2-2). There is also a lesser stream, Willow Brook that discharges to

Nonacoicus Brook to the north. Willow Brook originates from Robbins Pond and is fed by Robbins Pond, surface water runoff, storm water discharge, and groundwater. On the west side of the Nashua River there are also a number of tributaries west of Devens, specifically Catacoonamug Brook, Trout Brook, Morse

Brook, Walker Brook, and Mulpus Brook. The groundwater flow direction at each AOC is addressed in applicable sections.

Glacial meltwater deposits constitute the primary overburden aquifer at Devens. Groundwater also occurs in the underlying bedrock; however, flow is limited because regional bedrock lacks primary porosity and/or has been affected by metamorphism that limits transmissivity (an example would be the degree of development of transmissive partings parallel to layering). The result is bedrock groundwater flow that is primarily via fractures and dissolution voids.

The zones of highest transmissivity within the overburden are found in areas of thick glacial meltwater

(outwash) deposits on the former Main Post at Devens, and these encompass deposits in which the

Shabokin, Patton, MacPherson, and Grove Pond water supply wells are screened (Figure 2-6). Due to the high transmissivity of these overburden deposits, these areas are preferential groundwater flow areas. The zones of lowest transmissivity are typically associated with exposed till and bedrock.

Groundwater recharge occurs in upland areas and groundwater flows generally from the topographic highs to topographic lows. Groundwater discharges in wetlands, ponds, streams, and directly into the Nashua

River.

The Devens Groundwater Use and Value is categorized as “High” as determined by MassDEP (MassDEP, 2003) and the MassDEP groundwater classification of GW-1 is applied throughout Devens. The MassDEP approved water supply Zone II’s, as well as the potentially productive aquifer areas, and the Devens Aquifer

Protection and Watershed Protection Districts are shown on Figure 2-6.

The synoptic water level measurements taken for the PFAS RI in the areas addressed in this report are presented in Tables 2-2, 2-3, 2-4, and 2-6. The groundwater elevation contour maps based on those measurements are on Figures 2-7, 2-8, 2-9, 2-10, 2-12, and 2-13. A synoptic event was performed at SHL

2-4 in October 2019 (Table 2-5, Figure 2-11) in support of the long-term monitoring (LTM) program and is provided in this report for reference. The contour intervals vary between figures based on the level of scale and area of interest. The groundwater flow directions and gradients are discussed in the applicable sections.

3-1

3.0 AOC 32/43A PRELIMINARY SITE CHARACTERIZATION SUMMARY

Site Description

The AOC 32/43A and surrounding areas have been redeveloped and currently consist of large warehouse type buildings (constructed in 2001 and 2007) and paved areas. The area is generally flat with the land sloping down to a wetland north of the Devens Recycling Center.

The area is zoned Rail, Industrial & Trade Related. There are no wells in the area that are used for drinking water supply, irrigation water supply, or any other water supply purposes. A permit is required from Devens

Enterprise Commission for installation of any water supply well.

Facility History and Utilities

AOC 32 (former DRMO Yard) historically consisted of three fenced areas (West Yard, East Yard, and Tire

Recycling Area) along Cook Street (Figure 3-1). The West Yard, a paved area formerly used for the storage of used equipment containing lead-acid batteries, as well as for storage of telecommunications and administrative equipment; the former East Yard, a paved area that was used for disassembling vehicles for reusable parts; and the Tire Recycling Area, an unpaved area used for the storage and recycling of tires.

Records indicated that the facility was actively used by the Army from approximately 1964 to 1995 (KGS, 2017). In addition, a former waste oil underground storage tank site, located just northeast of the former

DRMO Office, was also incorporated into AOC 32.

South of AOC 32 is a series of underground storage tanks (UST), aboveground storage tanks (AST), and gasoline pump stations, that was name AOC 43A (former POL Storage Area). During the 1940s and 1950s, AOC 43A, was a fenced lot that served as a distribution facility for all the gasoline stations at Fort Devens.

The distribution facility formerly consisted of a main gasoline station, a pump house (former building T-

401) with five fuel USTs and four fuel ASTs, railroad tracks, an asphalt driveway led into the POL Storage

Area from Antietam Street (Figure 3-1) [Stone & Webster Environmental Technology and Services (S&W), 1998].

The land where historic AOC 32/43A source areas are located was redeveloped to include paved areas and a large warehouse constructed in 2001 (Nobis, 2005). The current owner, O’Reilly Auto, purchased the property in 2013. The land where DRMO West Yard was located is owned by JPR Trust (purchased in

2000). The land east of AOC 32/43A was divided and the northern parcel sold to Devens Recycling Center, LLC (purchased in 2006) and the southern parcel is currently owned by National Ind Portfolio Borrower, LLC (purchased in 2007). The National Ind Portfolio Borrower, LLC property is undeveloped. The Devens

Recycling Center was constructed by 2007. The Devens Recycling Center had a large fire at the facility in

May 2015. Sixty 5-gallon pails of aqueous film forming foam (AFFF) were used to extinguish the fire

(KGS, 2017). The facility is a construction and demolition debris processing center.

The current and previous subsurface features are shown on Figures 3-2 and 3-3. The current stormwater system around the Devens Recycling Center discharges storm water to detention areas south and southwest of the center and an infiltration gallery southeast of the center.

Remedial Status

Prior to the PFAS investigation, investigations, remediation, and post-remediation monitoring has occurred at AOCs 32 and 43A, under the CERCLA program, to address issues related to the USTs and ASTs identified at the sites described above. A brief summary of those activities is presented below.

At AOC 32, in 1991, a SI was performed at the DRMO Yard. Two operable units were included, a soils operable unit, that included the excavation and off-site disposal of soil and a groundwater operable unit associated with a waste-oil UST. Excavated soils were removed from the East Yard and the former Tire

Recycling Yard (KGS, 2017). Analytical findings of the SI reported xylene and petroleum contamination in soil and groundwater.

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In 1994, a RI was conducted and concluded that soil and groundwater contamination at the site required further remedial action [Ecology and Environment, Inc. (E&E), 1994]. Potential remedial alternatives were presented in a feasibility study (FS) and the preferred alternative was presented in a proposed plan. The record of decision (ROD) documented the final choice of remedy for cleanup of soils by excavation with off-site disposal and cleanup of groundwater by monitored natural attenuation (MNA) (Horne, 1998).

Remedial actions for the soil included the removal and disposal of metal debris; the removal and disposal of soil contaminated with petroleum, pesticides, and lead; and the removal and disposal of non-hazardous soil containing shredded tire scrap (S&W, 2000a).

In 1999, MNA field activities commenced at AOC 32 and a final assessment and recommendations report concerning the effectiveness of the MNA based on ROD criteria was presented in February 2000. The report determined that natural attenuation, supplemented with long-term groundwater monitoring and the establishment of institutional controls, would be an effective remedial action for AOC 32 (S&W, 2000c).

Monitoring of the groundwater at the site has continued and the results reported on an annual basis.

At AOC 43A, between 1965 and 1972, four fuel oil ASTs were removed. In 1989 and 1990, five fuel oil

USTs were located, and the adjacent soils were excavated and removed from the site, respectively. Five

USTs and 800 cubic feet of contaminated soil was removed from the site. Total petroleum hydrocarbons were detected in soil collected during the excavation (E&E, 1994). This remedial action removed the source from AOC 43A.

In 1991, five new USTs were installed in the POL Storage Area and were used to store fuel for military vehicles. In 1992, the Army conducted a SI and reported low levels of xylene and elevated petroleum in subsurface soils. In 1994 a RI was conducted to determine the nature and distribution of the detected contamination. Findings of the RI concluded that groundwater contamination required a remedial action evaluation (S&W, 2000b). Potential remedial alternatives were presented in a FS and the preferred alternative was presented in a proposed plan. The 1998 ROD documented the final remedy choice of institutional controls and MNA long-term monitoring (Horne, 1998).

Per the ROD, long-term monitoring has continued at AOC 32/43A.

PFAS Field Investigation

The RI field investigation at AOC 32/43A included sampling existing monitoring wells, collecting a surface water and sediment sample from the detention pond north of the Devens Recycling Center, groundwater vertical profiling using direct push technology (DPT), soil borings using DPT, piezometer installation, and synoptic water level events. The work was completed in general accordance with the Area 2 Field Sampling

Plan Addendum to Remedial Investigation Work Plan for Per- and Polyfluoroalkyl Substances (PFAS)

(KGS, 2018b). Field activities were added as the data was received and reviewed. Sampling locations are presented on Figure 3-4 and summarized in Table 3-1. The results are discussed in Section 3.5.

Existing Wells

Groundwater samples were collected from existing monitoring wells at AOC 32/43A from November 2018 to January 2019 in accordance with the Area 2 Field Sampling Plan Addendum to Remedial Investigation

Work Plan for Per- and Polyfluoroalkyl Substances (PFAS) (KGS, 2018b) (Table 3-1, Figure 3-4). A sample could not be collected from 32Z-01-11-XBR. The well was dry in the 2018/2019 Winter and in the

2019 Spring.

Groundwater samples were collected from one existing monitoring well (32M-01-14XBR) at AOC 32 in

November 2019 and May 2020 in accordance with the Work Plan for Additional Sampling of Existing Wells to Support the PFAS Remedial Investigation Former Fort Devens Army Installation, Devens, MA (KGS, 2019). The groundwater results are discussed in Section 3.5.

3-3

Surface Water and Sediment

A surface water and sediment sample was collected from the detention pond north of the Devens Recycling

Center in December 2018, in accordance with the Area 2 Field Sampling Plan Addendum to Remedial

Investigation Work Plan for Per- and Polyfluoroalkyl Substances (PFAS) (KGS, 2018b). The results are discussed in Section 3.5.

DPT Vertical Profiles

Two phases of DPT vertical profiles were conducted at AOC 32/43A. As results were received and reviewed, additional profiles were conducted to better delineate the PFAS contamination. The DPT vertical profiles are described below, are shown on Figure 3-4 and are summarized in Table 3-1.

AOC 32

The first round of vertical profiles at AOC 32 (32VP-19-01 through -08) was conducted from February into

June 2019 downgradient of the area of historic AOC 32 contamination (Table 3-1, Figure 3-4).

Review of the initial vertical profile results and the existing monitoring well results at AOC 32 indicated that the highest concentrations in the area were north of the Devens Recycling Center at 32VP-19-01. Based on these results, a second set of vertical profiles (32VP-19-09 through -12) was completed. Two vertical profiles were conducted downgradient of 32VP-19-01 (32VP-19-09 and -10), one vertical profile was conducted northeast of the paved area where water and AFFF foam from extinguishing the fire may have runoff the pavement (32VP-19-11), and one vertical profile was conducted downgradient of the infiltration gallery that is a component of the storm water management system that collects storm water on the east side of the Devens Recycling Center (32VP-19-12). These four vertical profiles were conducted in

September 2019. The results are discussed in Section 3.5.1.

AOC 43A

Four vertical profiles at AOC 43A (43AVP-19-01 through -04) were conducted in March to May 2019 downgradient of existing AOC 43A monitoring wells (Table 3-1, Figure 3-4). Based on review of the vertical profile results [maximum perfluorooctanoic acid (PFOA) + perfluorooctanesulfonic acid (PFOS) of 30.0 nanograms per liter (ng/L)] and existing monitoring well results (maximum PFOA + PFOS of

34.0 ng/L at 43M-01-17XBR) from AOC 43A and existing AOC 32 monitoring wells near AOC 43A, additional vertical profiles were not conducted at AOC 43A. The results are discussed in Section 3.5.1.

DPT Soil Borings

A total of 11 soil borings (32SB-19-01 through -11) were conducted at AOC 32 in October 2019. The locations of the soil borings were determined after review of the groundwater results from the existing wells and the vertical profiles (Figure 3-1). At 32SB-19-04, refusal occurred at a maximum depth of three feet below ground surface (bgs) during three attempts within the area cleared of subsurface utilities. Soil samples were not collected from this location. The soil borings activities were conducted accordance with the Area 2 Field Sampling Plan Addendum to Remedial Investigation Work Plan for Per- and

Polyfluoroalkyl Substances (PFAS) (KGS, 2018b). The results are summarized in Section 3.5.

Piezometer Installation

Two piezometers (32PZ-19-01 and -02) were installed in September and October 2019.

Synoptic Water Level Surveys

Two synoptic water level monitoring events that encompassed AOC 32/43A were conducted. One event was conducted in December 2018 and one was conducted in April 2020. All of the results are discussed in

Section 3.5.

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PFAS Nature and Extent

Groundwater PFAS results are summarized on Figure 3-5 and in cross section (Figures 3-6 through 3-8).

Soil sampling results are summarized on Figure 3-9. Surface water and sediment sampling results are summarized on Figure 3-10. Site-specific groundwater contour figures are presented on Figures 2-7, 2-8, 2-12, 2-13, and 3-5. All of the PFAS results from the RI are presented in tables in Appendix H. The media specific criteria are presented in Table 1-1.

Groundwater

Groundwater at AOC 32 was characterized through existing monitoring wells and vertical profiles. At AOC

32, vertical profile samples were collected from 12 locations. A total of 87 vertical profile samples were collected from AOC 32. Table 3-2 provides summary statistics of the results of the vertical profile samples.

Of those samples, 12 samples (14%) of the samples had concentrations greater than the EPA LHA and 57 samples (66%) had concentrations greater than the Massachusetts Contingency Plan (MCP) Method 1

Groundwater (GW-1) standard. Table 3-3 provides summary statistics of the results of the monitoring well samples in the AOC 32 area, which includes a few wells installed for SHL, specifically SHL-12, SHL-17, SHL-25, and SHM-93-24A. Of the 25 monitoring well samples collected, 7 samples (28%) had concentrations greater than the EPA LHA and 23 samples (92%) had concentrations greater than the GW-

1. None of the concentrations were greater than the GW-3 standard (protective of surface water). The wells at AOC 32 are located in overburden and shallow bedrock.

The summary statistics table provides data with respect to individual compounds (e.g., number of samples with PFOA that exceed the EPA LHA and the GW-1 standard) and with respect to the sum of applicable compounds in the EPA LHA and the GW-1 standard (e.g., numbers of samples with the sum of

PFOA+PFOS that exceed the EPA LHA, and number of samples with the sum PFOA+PFOS+ perfluorohexanesulfonic acid (PFHxS) + perfluoronanoic acid (PFNA) + perfluoroheptanoic acid

(PFHpA)+perfluorodecanoic acid (PFDA) that exceed the GW-1 standard]. Due to the summing of concentrations needed for comparison to the EPA LHA and the GW-1 standard, the numbers of samples that exceed the EPA LHA or GW-1 standard for individual compounds may not equal the numbers of samples that exceed the sum of the appropriate compounds for the EPA LHA or GW-1 standard. One example is, if individual results of PFOA and PFOS were both below the EPA LHA, but the sum of the results exceeded the EPA LHA, then the sample would be counted as an exceedance of the EPA LHA even though the individual compounds would not be counted as exceedances.

At AOC 32, as indicated on Figure 3-5, PFAS was detected at concentrations greater than the EPA LHA at the tire recycling yard (32Z-01-07XOB), within and downgradient of the approximate historic extent of petroleum contamination (32M-01-14XBR and SHL-12), north of the Devens Recycling Center (32VP-19-

01, -09, and -10), and downgradient of the infiltration gallery associated with the storm water collection system around the Devens Recycling Center (32VP-19-12 and -05). All of the locations had at least one groundwater sample that had PFAS concentrations greater than the GW-1 standard, except 32M-01-16XBR and SHL-17.

The maximum PFAS concentrations were detected off the north edge of the pavement from the Devens

Recycling Center at 32VP-19-01, in the shallowest sample interval (17-21 ft bgs). The detected concentrations of PFOA + PFOS was 2,880 ng/L and the sum of the six GW-1 compounds was 4,300 ng/L.

At 32VP-19-01, PFAS concentrations greater than the EPA LHA were detected from 17 to 41 ft bgs (24 ft thick) and concentrations above the GW-1 standard were detected from 17 to 51 ft bgs (34 ft thick).

Downgradient (i.e., north/northeast) of 32VP-19-01 at 32VP-19-02, the maximum concentrations were detected at 32-36 ft bgs with lesser concentrations detected throughout the saturated overburden. PFAS concentrations greater than the GW-1 standard were detected at 32VP-19-02 from 12 to 70.5 ft bgs (except at 22-26 ft bgs). Downgradient of 32VP-19-01 at 32VP-19-09, and -10, PFAS concentrations greater than the EPA LHA and GW-1 standard were detected in the shallowest sample interval as well as deeper in the aquifer, but not continuously throughout the thickness of the saturated overburden. At 32VP-19-09 PFAS

3-5 concentrations greater than the EPA LHA were detected from 12 to 16 ft bgs and 49 to 73 ft bgs and PFAS concentrations greater than the GW-1 standard were detected from 12 to 16 ft bgs, 29 to 33, and 49 to 73 ft bgs. At 32VP-19-10, PFAS concentrations greater than the EPA LHA were detected from 9 to 13 ft bgs and from 79 to 83 ft bgs and PFAS concentrations greater than the GW-1 standard were detected from 9 to

23 ft bgs, 79 to 83 ft bgs, and 99 to 103 ft bgs.

The second highest PFAS concentrations were detected downgradient of the infiltration gallery at 32VP-

19-12 with PFOA + PFOS = 449 ng/L and the sum of the six GW-1 compounds was 534 ng/L, in the shallowest sample interval (22 to 26 ft bgs). At 32VP-19-12, the PFAS concentrations greater than the EPA

LHA were only detected from 22 to 26 ft bgs and…