Final Report
Arsenic Fate, Transport and Stability Study
Groundwater, Surface Water, Soil and Sediment Investigation
Fort Devens Superfund Site
Devens, Massachusetts
September 30, 2008
Robert G. Ford1, Kirk G. Scheckel2, Steven Acree3,
Randall Ross3, Bob Lien1, Todd Luxton2, and Patrick Clark1
USEPA National Risk Management Research Laboratory
!Land Remediation and Pollution Control Division
Soils and Sediments Management Branch
Andrew W. Breidenbach Environmental Research Center
26 W. Martin Luther King Dr, Cincinnati, OH 45268
2Land Remediation and Pollution Control Division
Waste Management Branch
Center Hill Research Facility
5995 Center Hill Ave, Cincinnati, OH 45224
3Groundwater and Ecosystems Restoration Division
Applied Research and Technical Support Branch
Robert S. Kerr Environmental Research Center
919 Kerr Research Dr, Ada, OK 74820
SDMS DocID 296835
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Table of Contents ii
List of Figures iv
List of Tables viii
Notice ix
1 Introduction 10
1.1 Site Background 10
1.2 Scope and Objectives 12
1.3 References 12
2 Hydrologic Studies 14
2.1 Monitoring Network 14
2.1.1 Groundwater Monitoring Wells 14
2.1.2 Surface Water Elevation Monitoring Point 15
2.1.3 Cove Piezometers 15
2.1.4 Sediment Temperature Sensors 15
2.2 Site Hydrology 15
2.2.1 Rainfall Data 16
2.2.2 SHL Extraction System Operation 16
2.2.3 Groundwater/Surface Water Elevation Data 16
2.2.4 Effects of SHL Extraction System on Groundwater Elevations at Red
Cove 17
2.2.5 Potentiometric Surface 18
2.2.6 Vertical Hydraulic Gradients 20
2.3 Hydraulic Conductivity Structure 20
2.4 Groundwater and Arsenic Flux 22
2.5 Seepage Measurements 23
2.6 Distribution of Groundwater Discharge to Red Cove 24
2.7 Hydrologic Summary 25
2.8 References 26
3 Groundwater Chemistry Studies 68
3.1 Monitoring Network 68
3.2 Groundwater Chemistry Trends: RSK Wells and Shepley' s Hill Landfill 68
3.3 Groundwater Chemistry Trends: RSK Wells and Red Cove 73
3.4 Groundwater Chemistry Summary 74
3.5 References 74
4 Surface Water and Sediment Chemistry Studies 90
4.1 Monitoring Network 90
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4.2 Sediment Chemistry 91
4.3 Surface Water Chemistry 92
4.4 Sediment and Surface Water Chemistry Summary 94
4.5 References 95
5 Summary and Recommendations 125
5.1 Red Cove - Existing Conditions 125
5.2 Analysis of Potential Remediation Alternatives 127
5.2.1 Groundwater 127
5.2.2 Sediments 129
5.3 Recommendations for Site Characterization 130
5.4 References 132
Appendix A. Site Maps 136
Appendix B. Location Data 139
Appendix C. Potentiometric Surface Data 143
Appendix D. Geologic Logs for Existing Wells Adjacent to Red Cove 147
Appendix E. Summary of field chemistry data for groundwater sampled from RSK wells
within Red Cove Study Area adj acent to Shepley' s Hill Landfill 154
Appendix F. Summary of field chemistry data for groundwater sampled from RCTW
wells within Red Cove Study Area adjacent to Shepley's Hill Landfill 161
Appendix G. Summary of field chemistry data for surface water sampled from within Red
Cove adjacent to Shepley's Hill Landfill 163
Appendix H. Summary of chemistry data for groundwater sampled from RSK wells within
Red Cove Study Area adjacent to Shepley's Hill Landfill 165
Appendix I. Summary of chemistry data for groundwater sampled from RCTW wells
within Red Cove Study Area adjacent to Shepley's Hill Landfill 172
Appendix J. Summary of chemistry data for surface water sampled from within Red Cove
Study Area adj acent to Shepley's Hill Landfill 174
Appendix K. Tabulated metal concentrations for sediment cores collected from the three
transects in Red Cove as determined by microwave assisted HNO3 extraction 176
Appendix L. Elemental concentrations as a function of depth for sediment cores collected
from the three transects in Red Cove 181
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IV
Figures
Figure 1. Supplemental monitoring network established near Red Cove. 28
Figure 2. Schematic diagram of piezometers constructed within Red Cove. 29
Figure 3. Locations of the sediment temperature data loggers deployed within Plow Shop
Pond. 30
Figure 4. Daily rainfall at Fitchburg Municipal Airport during Red Cove study period. 31
Figure 5. Daily water discharge from SHL treatment system between August 1, 2006 and
November 30, 2007. 32
Figure 6. Comparative plot of rainfall at Fitchburg Municipal Airport, groundwater
elevations at wells RSK7, RSK12, RSK15, RSK19, and RSK37, and surface
water elevations in Red Cove at monitoring point STAFF 1. 33
Figure 7. Hydraulic head differences between wells screened at the water table immediately
adjacent to Red Cove and surface water elevations measured at STAFF 1
compared with pond stage (STAFF 1) and rainfall measured at the Fitchburg
Municipal Airport. 34
Figure 8. Groundwater and surface water elevations during a period of abnormally high
pond stage during the fall of 2007. 35
Figure 9. Hydraulic head differences between wells screened at the water table immediately
adjacent to Red Cove and surface water elevations measured at STAFF 1
compared with pond stage (STAFF 1) and rainfall measured at the Fitchburg
Municipal Airport during the period of abnormally high pond stage in the fall of
2007. 36
Figure 10. Comparative plot of daily water discharge from the SHL treatment system,
groundwater elevations at wells surrounding Red Cove, and surface water
elevations in Red Cove measured at monitoring point STAFF 1 for the period
August 2006 to November 2007. 37
Figure 11. Comparative plot of daily water discharge from the SHL treatment system,
rainfall, groundwater elevations at wells immediately adjacent to Red Cove, and
surface water elevations in Red Cove measured at monitoring point STAFF 1 for
the period July 13 - 30, 2007. 38
Figure 12. Site-wide contour map of groundwater elevations on December 15, 2006,
provided in the 2006 annual report (CH2MHill, 2006). 39
Figure 13. Detailed comparison of groundwater elevations in wells surrounding Red Cove,
surface water elevations measured at STAFF 1, and rainfall at Fitchburg
Municipal Airport between April 8 and 26, 2007. 40
Figure 14. Detailed comparison of groundwater elevations in wells surrounding Red Cove,
surface water elevations measured at STAFF 1, and rainfall at Fitchburg
Municipal Airport between August 1 and November 14, 2007. 41
Figure 15. Potentiometric surface on April 26, 2007, produced using existing shallow wells
and enhanced RSK network. 42
Figure 16. Potentiometric surface on September 10, 2007, produced using shallow existing
wells and enhanced RSK network. 43
Figure 17. Potentiometric surface on November 7, 2007, produced using shallow existing
wells and enhanced RSK network. 44
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Figure 18. Well clusters used for determination of vertical hydraulic gradients and hydraulic
conductivity structure. 45
Figure 19. Potentiometric surface on April 26, 2007, and locations of lake-bed piezometers
in which hydraulic heads were measured in comparison to the pond level at the
same location. 46
Figure 20. Potentiometric surface on September 10, 2007, and locations of lake-bed
piezometers in which hydraulic heads were measured in comparison to the pond
level at the same location. 47
Figure 21. Potentiometric surface on November 7, 2007, and locations of lake-bed
piezometers in which hydraulic heads were measured in comparison to the pond
level at the same location. 48
Figure 22. Hydraulic conductivity profile at well cluster RSK1-7. 49
Figure 23. Hydraulic conductivity profile at well cluster RSK8-12. 50
Figure 24. Hydraulic conductivity profile at well cluster RSK13-15. 51
Figure 25. Hydraulic conductivity profile at well cluster RSK16-21. 52
Figure 26. Hydraulic conductivity profile at well cluster RSK36-43. 53
Figure 27. Potentiometric surface on November 7, 2007, and typical example of flowpaths
used in estimation of groundwater and dissolved arsenic flux. 54
Figure 28. Approximate locations of seepage measurements made using an advective flux
meter. 55
Figure 29. Locations of wells screened at the water table where groundwater temperatures
were measured using data loggers. 56
Figure 30. Groundwater temperature measured using data loggers in wells screened at the
water table surrounding Red Cove. 57
Figure 31. Classed posting map of sediment temperatures at 8:00 a.m. on March 20, 2007. 58
Figure 32. Classed posting map of sediment temperatures at noon on August 22, 2007. 59
Figure 33. Classed posting map of sediment temperatures at 8:00 a.m. on March 20, 2007 in
Red Cove. 60
Figure 34. Aerial locations of RSK and RCTW wells installed by EPA/ORD within the
groundwater aquifer adjacent to and underlying Red Cove. 75
Figure 35. Cross-sectional view of the distribution of screened depths of the EPA/ORD
groundwater chemistry monitoring network (RSK and RCTW wells) and nearby
wells installed by the Army. 76
Figure 36. Distribution of dissolved (0.45 |im filtered) arsenic as a function of depth within
the aquifer adjacent to Red Cove. 77
Figure 37. Comparison of bicarbonate (HCOs), ammonia-nitrogen (NH3-N) and sulfate
(804) concentrations as a function of depth among all RSK well clusters. 78
Figure 38. Patterns in the concentrations of dissolved (0.45 |im filtered) sodium (Na),
potassium (K), and chloride (Cl) are shown for RSK wells. 79
Figure 39. Patterns in the concentrations of bicarbonate (HCOs), dissolved (0.45 |im filtered)
calcium (Ca), dissolved iron (Fe), and dissolved arsenic (As; 0.45 |im filtered) are
shown for RSK wells. 80
Figure 40. Vertical trends in groundwater chemistry for RSK wells and existing wells within
the southern, central portions and just north of Shepley's Hill Landfill (SHL). 81
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Figure 41. Concentration of arsenic versus iron (left panel) and potassium (right panel) for
RSK wells and existing piezometer clusters in the southern and central portions of
Shepley's Hill Landfill. 82
Figure 42. Location of SHP-99-29X and N5- P2 wells within the central portion of
Shepley's Hill Landfill (SHL) relative to RSK well clusters adjacent to Red Cove. 83
Figure 43. Concentrations of ammonia (NHs-N) and methane (CH/t) measured in
groundwater for a subset of RSK wells and at SHL wells SHP-99-29X, N5-P2,
and N5-P1 during September 2007. 84
Figure 44. Measured concentrations of chloride (Cl), sodium (Na) and potassium (K) for
groundwater samples collected from RCTW wells during 2006-2007. 85
Figure 45. Spatial pattern in shallow groundwater chemistry underneath Red Cove sediments
based on contouring of chemical data collected for wells RCTW 1-10 during
August 2006. 86
Figure 46. Spatial pattern in shallow groundwater chemistry underneath Red Cove sediments
based on contouring of chemical data collected for wells RCTW 1-10 during
August 2007. 87
Figure 47. Comparison of the measured concentrations of dissolved (0.45 |im filtered)
arsenic and the arsenite [As(III)] chemical species in filtered groundwater
sampled from RSK and RCTW wells. 88
Figure 48. Location of push-point sampling locations for collection of sediment pore water
within Red Cove during September 2005. 96
Figure 49. Location of sampling locations for collection of sediment cores within Red Cove
during September 2005 (transects "T02" and "T03") and April 2007 (transect
"T01"). 97
Figure 50. Location of sediment cores relative to locations of temperature button transects
installed in sediments within Red Cove. 98
Figure 51. Spatial pattern in sediment pore water chemistry approximately 2 feet below the
sediment surface in Red Cove based on contouring of chemical data collected by
push-point sampling during September 2005. 99
Figure 52. Concentration of iron (Fe, wt%) in the core section retrieved from the sediment
surface for cores collected by EPA/ORD in Red Cove during September 2005 and
April 2007 (left panel). 100
Figure 53. A) Sediment core locations in Red Cove, red triangles indicate the location of the
sediment samples. B) Arsenic concentration profiles for the sediment cores. 101
Figure 54. Basis set of XANES spectra for arsenic model compounds used in fitting sample
spectra from sediment cores retrieved from Red Cove during September 2005
(Transects 2 and 3) and March 2007 (Transect 1). 102
Figure 55. Results from the speciation of arsenic by XANES analysis for sediment core
locations along Transect 1. 103
Figure 56. Results from the speciation of arsenic by XANES analysis for sediment cores
located along Transect 2. 104
Figure 57. Results from the speciation of arsenic by XANES analysis for sediment cores
located along Transect 3. 105
Figure 58. Total quantity and relative percentage of arsenic species present in the top two
inches of sediment collected from Red Cove (left panel). Distribution of acid-
extractable sulfur for shallow sediments in Red Cove (right panel). 106
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Figure 59. Water quality data at surface water sampling locations SW02B and SW02A for
April 2007. 107
Figure 60. Mineralogical characterization of suspended solids recovered from the water
column in Red Cove at the SW02 sampling location (0.57 feet above sediments; ft
bws = feet below water surface; ND = not detected). 108
Figure 61. Water quality data at surface water sampling locations SW02B and SW03 for
August 2007. 109
Figure 62. Water quality data at surface water sampling locations SW04 and SW05 for
September 2007. 110
Figure 63. Comparison of measured water chemistry relative to stability fields for
ferrihydrite [represented as Fe(OH)3], pyrite (FeS2), and mackinawite (FeS).
Platinum electrode readings of oxidation-reduction potential (ORP) were
converted to electron activity based on reference to the standard hydrogen
electrode. Ill
Figure 64. Relative stability of low-temperature sulfide mineral forms of iron (FeS) and
arsenic (As2Ss, poorly crystalline) based on comparison of measured water
characteristics (pH, ferrous iron, arsenite concentrations) to thermodynamic
predictions. 112
Figure 65. Comparison of the measured concentrations of dissolved arsenic and the arsenite
[As(III)] chemical species in filtered push-point and surface water samples from
Red Cove (left panel). 113
Figure 66. Evaluation of arsenic sorption data for suspended solids within the Red Cove
water column for sampling locations SW02A, SW02B, SW03, SW04 and SW05. 114
Figure 67. Measured concentrations of chloride (Cl), sodium (Na) and potassium (K) for
deep surface water samples and shallow groundwater sampled from RCTW wells
during 2006-2007. 115
Figure 68. Distribution of potassium (K) concentrations in shallow groundwater (RCTW
wells) and deep surface water above the sediment surface in Red Cove. 116
Figure 69. Comparison of sediment temperature distribution (August 22, 2007) to contoured
potassium concentrations (mg/L) in RCTW wells measured during August 21-23,
2007. 117
Figure 70. Comparison of arsenic (As) and potassium (K) concentrations for deep and
shallow surface water in Red Cove to concentrations observed in underlying
shallow groundwater (filtered, 0.45 |im). 118
Figure 71. Comparison of arsenic concentrations in sediment, deep surface water and
shallow groundwater in Red Cove. 119
Figure 72. Comparison in estimated groundwater fluxes of arsenic for RSK well locations to
the distribution of potassium in shallow groundwater (August 2007; RCTW well
contours) and the contoured distribution in sediment arsenic concentration based
on historical and EPA/ORD sediment data. 120
Figure 73. Cross-section through Red Cove (RC) showing relative locations of RSK and
RCTW wells along with surface water (SW) sampling locations. 133
Figure 74. Proposed locations for collection of additional groundwater chemistry data in the
saturated unconsolidated aquifer within the Shepley's Hill Landfill (SFIL) and
along the eastern edge of the landfill cap adjacent to Red Cove. 134
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Tables
Table 1. Average groundwater elevations in shallow wells surrounding Red Cove
compared to surface water elevations measured at STAFF 1 for the period August
2, 2006 to November 7, 2007. 61
Table 2. Average groundwater elevations in shallow wells surrounding Red Cove
compared to surface water elevations measured at STAFF 1 for the period October
4 to October 19, 2007. 62
Table 3. Vertical hydraulic gradients at well clusters surrounding Red Cove in 2005/2006. 63
Table 4. Vertical hydraulic gradients at well clusters surrounding Red Cove in 2007. 64
Table 5. Vertical hydraulic gradients between piezometers in Red Cove and surface water. 65
Table 6. Groundwater and Arsenic Flux Calculated from Potentiometric Surface Maps. 66
Table 7. Seepage Flow Measured Using a Bidirectional Advective Flux Meter. 67
Table 8. Concentration data for aquifer solids collected during purging of well screens at
RSK2 and RSK37 along with groundwater data collected on August 8, 2006
(RSK2) and August 22, 2007 (RSK37). 89
Table 9. Concentration of arsenic and speciation of the arsenic solid phase as determined
by linear combination fitting of XANES data for Transect 1. 121
Table 10. Concentration of arsenic and speciation of the arsenic solid phase as determined
by linear combination fitting of XANES data for Transect 2. 122
Table 11. Concentration of arsenic and speciation of the arsenic solid phase as determined
by linear combination fitting of XANES data for Transect 3. 124
Final Report
30 September 2008
EPA/ORD
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IX
Notice
This document is intended for internal Agency use only. All research projects making
conclusions or recommendations based on environmental data and funded by the U.S.
Environmental Protection Agency are required to participate in the Agency Quality Assurance
Program. This project was conducted under an approved Quality Assurance Project Plan (421-
Q10-1). The procedures specified in this plan were used without exception. Information on the
plan and documentation of the quality assurance activities and results are available from Kirk
Scheckel or Robert Ford.
The following individuals are acknowledged for assistance in field sampling, report preparation
and laboratory analyses: Thabet Tolaymat (USEPA/ORD-Cincinnati) and Aaron Williams
(former post-doctoral researcher; USEPA/ORD-Cincinnati); Brad Scroggins (USEPA/ORD-
Ada); Tim Bridges and Dan Granz (USEPA-Region 1 Laboratory) and personnel with Shaw
Environmental, Inc. under Contract 68-C-03-097. Ginny Lombardo (RPM), Bill Brandon, and
Rick Sugatt (USEPA-Region 1 Boston) provided project guidance and coordination of on-site
activities during this investigation. Carol Stein and Dave McTigue (Gannett Fleming, Inc.)
provided historical background for site investigations.
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1 Introduction
This document presents results from the Fiscal Years 2006-2007 field investigation at the
Shepley's Hill Landfill Superfund site to fulfill the research objectives outlined in the proposal,
'Fate and Transport of Arsenic in an Urban, Military Watershed' (Dr. Kirk Scheckel, EPA/ORD)
and the Arsenic Fate, Transport and Stability Study QAPP and Work Plan (Draft Version 3,
Revised 9 April 2007) prepared by EPA/ORD for the Fort Devens Superfund Site Remedial
Project Manager, Ginny Lombardo (EPA/Region I). The purpose of this study is to provide EPA
Region 1 with a technical evaluation of the distribution and flux of arsenic in shallow
groundwater adjacent to Red Cove and the fate, transport and stability of arsenic in sediments
and surface water following groundwater discharge.
The primary role of EPA/ORD was to investigate the migration of mobile forms of arsenic from
suspected source areas within the Shepley's Hill Landfill (Fort Devens Superfund Site) into the
Red Cove Study Area of Plow Shop Pond (Figure Al). Three goals were addressed as part of
this investigation: 1) identification of the mobile form of arsenic in groundwater, 2)
identification of the process(es) controlling arsenic uptake onto Red Cove Study Area sediments,
and 3) evaluation of the stability of arsenic associated with Red Cove Study Area sediments.
Synchrotron speciation techniques were utilized to determine the speciation of arsenic in
sediments. This information was used as a basis for determining the flux of arsenic discharging
into Red Cove from contaminated groundwater and to provide a preliminary assessment of the
influence of the existing groundwater extraction system on groundwater flux into the cove. The
information derived from this study was evaluated relative to potential remedial alternative(s) for
contaminated groundwater and sediments within and adjacent to the Red Cove Study Area.
1.1 Site Background
Fort Devens was established in 1917 as Camp Devens, a temporary training camp for soldiers
from the New England area. In 1931, the camp became a permanent installation and was
renamed Fort Devens. Throughout its history, Fort Devens served as a training and induction
center for military personnel, and as a unit mobilization and demobilization site. All or portions
of this function occurred during World Wars I and II, the Korean and Vietnam conflicts, and
operations Desert Shield and Desert Storm. During World War II, more than 614,000 inductees
were processed, and Fort Devens reached a peak population of 65,000. The primary mission of
Fort Devens was to command, train, and provide logistical support for non-divisional troop units
and to support and execute Base Realignment and Closure (BRAC) activities. The installation
also supports the Army Readiness Region and National Guard units in the New England area.
Fort Devens was selected for cessation of operations and closure under the Department of
Defense Base Realignment and Closure Act of 1990 (Public Law 101-510).
Shepley's Hill Landfill encompasses approximately 84 acres in the northeast corner of the
former Main Post at Fort Devens (Figure A2). Shepley's Hill Landfill includes three Areas of
Contamination (AOCs): AOC 4, the sanitary incinerator; AOC 5, sanitary landfill No. 1; and
AOC 18, the asbestos cell. AOCs 4, 5, and 18 are all located within the capped area at Shepley's
Hill Landfill. The three AOCs are collectively referred to as Shepley's Hill Landfill (USEPA,
1999). The landfill is situated between the bedrock outcrop of Shepley's Hill on the west and
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Plow Shop Pond on the east. Nonacoicus Brook, which drains Plow Shop Pond, flows through a
low-lying wooded area to the north of the landfill.
The southern end of the landfill borders the former Defense Reutilization and Marketing Office
(DRMO) yard. There was an exposed bedrock knob in this area southwest of the landfill, just
north of Market Street, and a second exposed bedrock knob further to the south, just north of the
intersection of Antietam and Carey Streets. As part of Devens redevelopment efforts, the
southern bedrock knob and a portion of the northern knob were removed to facilitate building
construction. In 2001, a 35,000 square foot building and associated paved areas were
constructed in the area of the former DRMO yard.
An area east of the landfill and south of Plow Shop Pond is the site of a former railroad
roundhouse which was investigated as Study Area 71.
Landfill operations at Shepley's Hill Landfill began at least as early as 1917, and stopped as of
July 1, 1992. During its last few years of use, the landfill received about 6,500 tons per year of
household refuse and construction debris, and operated using the modified trench method. A
portion of the waste was buried below the water table. In an effort to mitigate the potential for
off-site contaminant migration, Fort Devens initiated the Fort Devens Sanitary Landfill Closure
Plan in 1984 in accordance with Massachusetts regulations entitled "The Disposal of Solid
Wastes by Sanitary Landfill" (310 CMR 19.00, April 21, 1971). The Massachusetts Department
of Environmental Protection (MADEP) (then the Department of Environmental Quality
Engineering) approved the plan in 1985.
The Army performed a Remedial Investigation (RI) (E&E, 1993) and supplemental RI (ABB-
ES, 1993) at Shepley's Hill Landfill in accordance with CERCLA between 1991 and 1993. The
RI and RI Addendum reports identified potential human exposure to arsenic in groundwater as
the primary risk at Shepley's Hill Landfill. The RI Addendum Report also identified potential
ecological risks to aquatic and semi-aquatic receptors from exposure to Plow Shop Pond surface
water and sediments (USEPA, 1999).
Based on types of contaminants, environmental media of concern, and potential exposure
pathways, remedial action objectives were developed in the feasibility study to aid in the
development and screening of alternatives (ABB-ES, 1995). These remedial action objectives
were developed to mitigate existing and future potential threats to public health and the
environment (USEPA, 1999). The remedial objectives for the Shepley's Hill Landfill Operable
Unit are:
Protect potential residential receptors from exposure to contaminated groundwater
migrating from the landfill having chemicals in excess of Maximum Contaminant Levels
(MCLs).
Prevent contaminated groundwater from contributing to the contamination of Plow Shop
Pond sediments in excess of human-health and ecological risk-based concentrations.
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1.2 Scope and Objectives
The field sampling activities and laboratory analyses outlined in the work plan (USEPA ORD,
Draft Version 3, Revised 9 April 2007) provide a current assessment of arsenic distribution in
groundwater, sediments and surface water within the Red Cove Study Area of Plow Shop Pond
adjacent to Shepley's Hill Landfill. Activities were directed towards the collection of sediment
and limited soil (aquifer solids) materials for laboratory studies and aqueous samples to assess
the chemical speciation of arsenic and chemical conditions in groundwater and surface water.
Collection of sediment materials for laboratory characterization facilitated assessment of the
chemical speciation and stability of solid phase arsenic. These data provided a means for 1)
assessing the long-term assimilative capacity within the unconsolidated aquifer material and the
down gradient environment, and 2) the potential for future mobilization of arsenic that is
partitioned to sediment solids. In order to provide context for observations of groundwater
hydrology and chemistry within the Red Cove Study Area, existing interpretations of site
hydrology and reported groundwater chemistry for the aquifer underlying Shepley's Hill Landfill
were reviewed (Section 3).
The research effort was divided between field-based sampling and laboratory-based
characterization. Installation of the monitoring network and sampling was conducted during the
period September 2005 to November 2007. Reporting and analysis of data resulting from this
effort are presented in the following order: 1) Section 2 - hydrologic studies, 2) Section 3 -
groundwater chemistry, and 3) Section 4 - sediment and surface water chemistry. Where
possible, comparisons are made between data collected from the EPA/ORD monitoring network
to historical and concurrent data from the existing site groundwater monitoring network
(CH2MHill, 2006) and sediment sampling conducted within Plow Shop Pond (Gannett Fleming,
2006). The result of this analysis is summarized for the Red Cove Study Area in Section 5,
which also includes recommendations for alternative remediation strategies for contaminated
groundwater and sediments.
1.3 References
ABB Environmental Services, Inc. (ABB- ES) 1993. "Final Remedial Investigation Addendum
Report". Prepared for the U. S. Army Environmental Center, Aberdeen Proving Ground,
Maryland. Arlington, Virginia.
ABB Environmental Services, Inc., 1995. "Draft Consolidation Landfill Feasibility Study
Report". Prepared for the U. S. Army Environmental Center, Aberdeen Proving Ground,
Maryland. Arlington, Virginia.
CH2MHill, 2006 Annual Report, Shepley's Hill Landfill Long Term Monitoring & Maintenance,
Devens, Massachusetts". Prepared for the Department of the Army, BRAC Environmental,
Devens, Massachusetts.
Ecology and Environment, Inc. (E&E), 1993. "Final Remedial Investigations Report for Areas
of contamination 4, 5, 18, 40, Fort Devens, Massachusetts". Prepared for the U. S.
Army Toxic and Hazardous Materials Agency, Aberdeen Proving Ground, Maryland.
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Arlington, Virginia.
Gannett Fleming, Inc., 2006. "Final Expanded Site Investigation, Grove Pond and Plow Shop
Pond, Ayer, Massachusetts", prepared for the U. S. Environmental Protection Agency, Region 1,
Boston, Massachusetts, (http://www.epa.gov/ne/superfund/sites/devens/246620.pdf)
USEPA. Fort Devens (OU2) Record of Decision, Landfill Remediation Study Areas 6, 12, and
13 and Areas of Contamination (AOC) 9, 11, 40, AND 41, U.S. Army Reserve Forces Training
Area, Devens, Massachusetts; MA7210025154; July 21, 1999.
(http://www.epa.gov/superfund/sites/rods/fulltext/r0199504.pdf)
USEPA Office of Research and Development (ORD). Arsenic Fate, Transport and Stability
Study QAPP and Work Plan, Groundwater, Surface Water, Soil and Sediment Investigation, Fort
Devens Superfund Site, Fort Devens, Massachusetts, Draft Version 3, Revised 9 April 2007
(QAPP ID 421-Q10-1).
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2 Hydrologic Studies
The objectives of the hydrologic studies performed at the Fort Devens sediments research site
included:
Determination of groundwater flow rates and directions within the unconsolidated
overburden in the Red Cove area of Plow Shop Pond,
Estimation of groundwater and associated arsenic flux rates in the overburden,
Evaluation of the spatial and temporal nature of groundwater/surface water interactions
within the study area, and
Preliminary evaluation of the effects of the SHL extraction system on groundwater
elevations adjacent to Red Cove and groundwater discharge to the cove.
Investigations included installation of wells and piezometers in the vicinity of Red Cove, the
measurement of groundwater and surface water elevations, estimation of the hydraulic
conductivities of unconsolidated materials surrounding Red Cove, and the measurement of
sediment temperatures within the cove. Data and results from these studies are discussed below.
2.1 Monitoring Network
Forty monitoring wells (Figure 1) were installed in the overburden in the vicinity of Red Cove to
estimate groundwater flow rates and directions. Twelve piezometers were installed in Plow
Shop Pond to allow comparison of hydraulic head within the sediments with that of the pond. A
network of temperature sensors was also installed in the shallow sediments beneath Red Cove to
characterize temporal and spatial variability in sediment temperatures as an indicator of the
possible distribution of groundwater discharge to the pond. In addition, a sensitive bidirectional
advective flux meter (Lien, 2006) was used to measure the magnitude and direction of water
movement across the sediment/water interface at four locations in Red Cove.
2.1.1 Groundwater Monitoring Wells
Initially, twenty-one wells were installed in four clusters surrounding Red Cove in September
2005 using a Geoprobe 6600 rig. The clusters were designed to provide complete vertical
coverage from the depth of drilling refusal to the water table. The depth of drilling refusal is
assumed in this case to be at or very close to the base of the unconsolidated material. In order to
validate this assumption, the elevations of the top of bedrock described in geologic logs from
existing wells N2, SHL4, and N3 were compared with the elevation of drilling refusal at the
locations of the RSK1-7, RSK13-15, and RSK36-43 well clusters, respectively. The difference
between the elevation of drilling refusal and the top of bedrock from existing logs was 5.5 ft, 0.3
ft, and 1.7 ft at RSK1-7, RSK13-15, and RSK36-43, respectively. Given that the bedrock
topography appears to vary significantly in this area and the well clusters are as much as 50 ft
away from the locations where bedrock elevations are known (RSK1-7 cluster to well N2), these
relatively small differences between drilling refusal and known bedrock elevations indicate the
well clusters likely penetrate the entire thickness of unconsolidated materials at each location.
Following an initial period of characterization, additional wells were installed in April 2007 to
better determine the hydraulic conductivity structure and arsenic concentrations along the
southern shore of Red Cove as well as hydraulic gradients surrounding the cove.
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The majority of the wells are constructed using 1-in Schedule 40 PVC casing and screens 5 ft in
length. The slot size for well screens installed in September 2005 was 0.020 in. The slot size for
screens used in installation of subsequent wells was 0.010 in. All wells were installed through
the Geoprobe rods allowing the formation to collapse around the well as the rods were removed.
A bentonite seal was placed from the water table to ground surface and the wells were finished
with locking well caps. The wells were surveyed into the existing site-wide network using a
Topcon Model CTS-2 Total Station and location data for nearby wells surveyed by CH2M Hill.
The surveys were performed using procedure RSKSOP 292.
2.7.2 Surface Water Elevation Monitoring Point
In August 2006, a monitoring point for surface water elevation (Figure 1), equivalent in function
to a traditional staff gauge, was established near well cluster RSK16-21 in the northwestern
section of Red Cove. The monitoring station was constructed using 2-in Schedule 40 PVC
screen anchored in the shallow pond sediments using a steel rod. A reference point at the top of
the screen was surveyed into the existing well network using the Topcon Model CTS-2 Total
Station and procedure RSKSOP 292.
2.1.3 Cove Piezometers
In April 2007, twelve piezometers (Figure 1) were installed into the sediments beneath Plow
Shop Pond. The piezometers are constructed of steel pipe connected to stainless steel screened
drive points 0.5 ft in length. The screened points were driven to an average depth of 5 ft below
the sediment/water interface using a sliding hammer. Depth of piezometer placement was
generally the depth of refusal at each location. It is estimated that the location of the sediment
surface may be in error by a maximum of 0.5 ft due to the interference in aquatic plant matter
towards positive identification of the sediment surface. A stilling well constructed of 1-in
Schedule 40 PVC pipe was attached to each piezometer (Figure 2) such that the top of the
piezometer and top of the stilling well are at the same elevation. This construction allows the
difference in hydraulic head between the surface water and the groundwater beneath the pond to
be measured relative to the same reference point using a standard water level indicator. In this
way, the accuracy of each measurement is the same as that of a water level measurement in a
conventional well (i.e., 0.01 ft). Therefore, the accuracy of the calculated difference in hydraulic
heads is expected to be within 0.02 ft. While the elevation of the piezometer screen may be in
error by about 0.5 ft, this does not impact the accuracy of the difference in hydraulic head.
Location data for both the monitoring wells and piezometers are provided in Appendix B.
2.1.4 Sediment Temperature Sensors
In October 2006, an array of approximately one hundred small diameter temperature data loggers
was deployed in three transects across Red Cove (Figure 3). In addition to the loggers in the
transects, several individual loggers were deployed at locations within and adjacent to Red Cove.
The temperature loggers, manufactured by Dallas Semiconductor, have a reported precision and
accuracy of approximately +/- 0.9 deg F (Johnson etal., 2005). The temperature loggers were
placed in waterproof housings and buried at a depth of approximately 1.0 ft below the top of the
sediments. The array was used to record sediment temperatures every four hours between
October 2006 and September 2007.
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2.2 Site Hydrology
Based on the site setting, influences on groundwater flow rates and directions within the
overburden in the study area may include precipitation, surface water elevation in Plow Shop
Pond, and groundwater extraction from the Shepley's Hill Landfill (SHL) pump-and-treat
system. For this investigation, groundwater elevations in wells immediately adjacent to Red
Cove and surface water elevations at the staff gauge located in the western portion of Red Cove
were monitored at a minimum of every four hours using pressure transducers/data loggers. Since
data from an on-site meteorological station were not available, precipitation data for the period
of interest were obtained for the station located at the Fitchburg Municipal Airport in Fitchburg,
Massachusetts. The Army provided data and information regarding the water flow rates and
daily discharge volumes for the SHL extraction system.
2.2.7 Rainfall Data
Daily total rainfall data were obtained for September 2005 through November 2007 (Figure 4)
for the meteorological station at the Fitchburg Municipal Airport from the National Climatic
Data Center of the National Oceanic and Atmospheric Administration. It is noted that the station
is located approximately twelve miles from the study site. Although the magnitude of
precipitation at the Fitchburg station may differ from that in the study area, the precipitation
patterns should be sufficiently similar to allow identification of the time periods most affected by
rainfall and, therefore, the possible influence of precipitation on groundwater and surface-water
elevations at the site. For this purpose, an on-site meteorological station was not deemed to be
necessary. A more quantitative analysis of the effects of rainfall on hydraulic gradients would
require site-specific measurements of rainfall.
2.2.2 SHL Extraction System Operation
The SHL groundwater remediation system began operation in March 2006. Measurements of the
raw water flow to the treatment system and, beginning in August 2006, daily measurements of
the total volume of treated water discharged from the system were provided by the Army. For
purposes of this analysis, the reported volume of water discharged on a daily basis (Figure 5)
was used as a measure of the relative changes in total system extraction rates through time. It is
noted that the discharge water volume reportedly includes the volume of chlorine dioxide used
during treatment in addition to the volume of water extracted from the wells (Simeone, 2007).
The rate of chlorine dioxide addition was reported in May 2007 to typically be 1.3 gal/min.
Since these data are only used to identify time periods of particular interest for evaluating the
possible influence of the pumping system on groundwater/surface water interactions at Red
Cove, the inclusion of a relatively small contribution to flow beyond that of extracted
groundwater was considered to have no significant effect on the results. Notable features of the
system performance include the reduction in down time beginning in March 2007 and the
increase in combined extraction rate to greater than 40 gpm beginning in July 2007.
2.2.3 Groundwater-/Surface Water Elevation Data
Groundwater elevations were recorded at a minimum frequency of six times per day in four
wells surrounding Red Cove (RSK7, RSK12, RSK15, and RSK19) using pressure
transducers/data loggers starting in September 2005 (Figure 1). The staff gauge was added to
this network in August 2006 and RSK37 was added in September 2007. The data (Figure 6)
indicate significant temporal fluctuations in both groundwater and surface water elevations
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occur, primarily associated with rainfall events. Groundwater elevations in wells immediately
adjacent to the cove respond rapidly to precipitation events and changes in surface water levels
which are often, but not always (e.g., October 2007), correlated with precipitation. In general,
rainfall events with a magnitude of 0.5 in or more reported at the Fitchburg Municipal Airport
resulted in a noticeable increase in both surface water and groundwater elevations. However, the
magnitude of the increase is likely related to several factors, including the near-term cumulative
rainfall.
The average groundwater elevations (Table 1), as measured in wells screened at the water table
in each well cluster, indicate that the net direction of groundwater flow was toward Red Cove in
this area between August 2, 2006, and November 7, 2007. Well RSK37, located on the southern
shore of Red Cove, was not included in this comparison. The data set for this well (September
13 to November 7, 2007) was too small to support meaningful comparisons.
A comparison of the temporal fluctuations in hydraulic head differences between groundwater
elevations measured in water-table wells surrounding Red Cove and surface water elevations
(Figure 7) indicates that hydraulic gradients also respond to rainfall and changes in pond stage.
Hydraulic gradients toward the pond decrease rapidly in association with rapid increases in pond
stage. On several occasions during the fall of 2006, April 2007, and the fall of 2007, surface
water elevations were temporarily higher than groundwater elevations at well RSK7. During the
fall of 2007, surface water elevations were also higher than groundwater elevations measured at
each of the well clusters surrounding the cove for very brief periods of time (Figure 8)
corresponding to rapid increases in pond elevation during an extended period of abnormally high
pond stage. This indicates that the normal direction of groundwater flow reversed and surface
water from Red Cove briefly recharged the aquifer during these periods. These gradient
reversals appear to be associated with brief lags in the response of the aquifer to rapid changes in
pond stage and are not considered to be significant in the overall interpretation of groundwater
flow surrounding the cove.
Examination of the data does not indicate that there is likely to be a simple, direct correlation
between pond stage and hydraulic gradient during periods of normal pond stage. However,
during the period of abnormally elevated stage between approximately mid-September and the
end of October 2007, hydraulic head differences in the immediate vicinity of Red Cove were
significantly lower than normal (Figure 7). Pond stage during this period was above an elevation
of 218 ft AMSL for approximately 35 days and both pond stage and hydraulic head differences
were relatively stable between October 4 and October 19 (15 days) (Figure 9). During this
relatively stable period between October 4 and 19, the average groundwater elevations in the
wells adjacent to Red Cove (Table 2) were significantly closer to the average elevation of the
pond than the average elevations for the period between August 2, 2006, and November 7, 2007
(Tablel). This indicates that net groundwater discharge to the pond should also be reduced
during this period of elevated pond stage. Further, it indicates that management of pond stage at
higher elevations may benefit remedial actions designed to eliminate discharge of contaminated
groundwater to Red Cove, assuming that such management was even feasible. A more
controlled study of the effects of pond elevation on hydraulic gradient would be required to
better quantify the potential benefits of such a strategy.
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2.2.4 Effects ofSHL Extraction System on Groundwater Elevations at Red Cove
Groundwater elevations in four shallow wells immediately adjacent to Red Cove (RSK7,
RSK12, RSK15, and RSK19) do not display obvious correlations with changes in extraction
rates of the SHL pump-and-treat system (Figure 10). Possible correlations between groundwater
elevations and pumping rates were also examined during the period July 14-29, 2007, when the
pumping system was taken offline for four days and restarted at an increased rate (Figure 11).
Daily extraction rates, rainfall at the Fitchburg Municipal Airport, and groundwater elevations
were plotted against time. These data do not indicate obvious correlations between groundwater
extraction and groundwater elevations immediately adjacent to the cove. It is likely that any
changes in groundwater elevations due to the ongoing extraction are subtle in this area and are
masked by the dominant influences of fluctuations in surface water elevations and precipitation,
which are evident in Figure 11. More intensive monitoring of additional wells between Red
Cove and the extraction wells would be required to discern the influence of the extraction system
in the study area.
It should be noted that an assessment of drawdown to simply demonstrate influence of a
pumping system is generally not an effective measure of extraction system performance with
respect to groundwater containment objectives. The performance metric of most interest in this
regard is the extent and temporal variability of the capture zone as indicated by such lines of
evidence as interpretation of potentiometric surfaces, evaluation of downgradient chemical data
trends, and, in this case, direct measurements of groundwater discharge to surface water.
Additional recommendations concerning evaluations of system performance with respect to
groundwater capture can be found in USEPA (2008). In this respect, regardless of whether any
observable influence exists in this area, the data clearly demonstrate that groundwater with
elevated arsenic concentrations continues to discharge to Red Cove, even at pumping rates
greater than 40 gpm.
2.2.5 Potentiometric Surface
At the site-wide scale, shallow groundwater appears to flow in a generally south to north
direction as indicated by the site-wide groundwater elevation data provided in the 2006 annual
monitoring report (Figure 12) and previous reports. In addition to the influence of the SHL
extraction system on groundwater flow in the northern portion of the site, Figure 12 also
indicates the potential for groundwater discharge into Red Cove and other areas in the southern
portion of Plow Shop Pond. In order to better define hydraulic gradients adjacent to Red Cove,
groundwater elevations were measured both in the RSK well network and in surrounding wells
on April 26, September 10, and November 7, 2007. In support of this effort, groundwater
elevations, surface water elevations, and rainfall were plotted for periods when potentiometric
data were obtained to better understand the hydrologic context (Figures 13 and 14).
A potentiometric surface representing the water table was produced from each of these data sets
(Figures 15-17). These potentiometric surfaces indicate groundwater flow toward Red Cove,
implying discharge of groundwater to the pond in this area. However, differences in the
hydraulic gradients indicate the magnitude of the discharge likely varied as well as the portion of
Plow Shop Pond that received discharge. Groundwater elevation data used to create the
potentiometric surfaces are provided in Appendix C.
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The groundwater elevation data from April 26, 2007, were obtained following a significant
rainfall event during which the pond level spiked (Figure 13). Groundwater extraction by the
SHL pump-and-treat system during the period immediately preceding the measurements appears
to have been relatively constant at a combined rate of approximately 25 gpm. Hydraulic
gradients near Red Cove (Figure 15) ranged from approximately 0.005 in the vicinity of well
RSK7 to approximately 0.013 near RSK15 with the potential direction of groundwater flow
toward the cove. The potential direction of groundwater flow was toward Plow Shop Pond from
the area of Red Cove as far north as well N1,P3. The groundwater divide separating
groundwater with flow directions toward the pond from water moving toward the SHL extraction
system was located in the vicinity of wells SHP-05-43, SHP-05-44, and the Nl cluster during the
time of these measurements.
The groundwater elevation data from September 10, 2007, were obtained following a period of
relatively minimal rainfall (Figure 14). Groundwater extraction by the SHL pump-and-treat
system during the period immediately preceding the measurements appears to have been
relatively constant at a combined rate of approximately 45 gpm. Hydraulic gradients near Red
Cove (Figure 16) ranged from approximately 0.002 in the vicinity of well RSK7 to
approximately 0.006 near RSK15 with the potential direction of groundwater flow toward the
cove. The groundwater divide separating groundwater with flow directions toward the pond
from water moving toward the SHL extraction system was located further south than during the
April measurements and was in the vicinity of the N2 well cluster.
The groundwater elevation data from November 7, 2007, were obtained following a period of
sporadic rainfall, including a precipitation event on the day preceding the water level
measurements (Figure 14). However, the major hydrologic influence on this data set appears to
be related to the sustained period of elevated pond stage and the rapid changes in surface water
levels during this period. Inspection of this figure indicates that there were even several very
brief periods during which surface water elevations at STAFF 1 were higher than groundwater
elevations in one or more of the monitoring wells, indicating the water in Red Cove temporarily
recharged the aquifer. The groundwater elevation measurements used to produce the
potentiometric surface were immediately preceded by a rapid decline in pond stage. Therefore,
this data set may be significantly affected by hydrologic factors not representative of normal
conditions. Groundwater extraction by the SHL pump-and-treat system during the period
immediately preceding the measurements appears to have been relatively constant at a combined
rate of approximately 40 to 45 gpm. Hydraulic gradients near Red Cove (Figure 17) ranged from
approximately 0.002 in the vicinity of well RSK7 to approximately 0.004 near RSK15 with the
potential direction of groundwater flow toward the cove. The groundwater divide separating
groundwater with flow directions toward the pond from water moving toward the SHL extraction
system was located further south than during the measurements made in either April or
September and was in the vicinity of wells RSK7 and N2,P2.
Hydraulic gradients measured during September and November in the vicinity of Red Cove were
significantly lower in magnitude than in April, implying that flux of groundwater discharging to
the cove was also significantly less than in April. The difference in hydraulic gradients may
have largely been due to the increased precipitation prior to the measurements in April. More
intensive monitoring of a greater portion of the well network between Red Cove and the SHL
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extraction system would be required to determine whether the extraction system may also have a
significant impact on hydraulic gradients in this area of the site.
2.2.6 Vertical Hydraulic Gradients
Vertical hydraulic gradients (iv) estimated through comparisons of hydraulic head in co-located
shallow and deep monitoring points provide information regarding the potential direction for
vertical movement of groundwater. In the area of Red Cove, periodic measurements of hydraulic
head in wells screened at the water table and at the bottom of the unconsolidated materials were
made using a water level indicator at each of the well clusters surrounding the cove (Figure 18).
Similar measurements were also made in the piezometers screened in the pond sediments and in
the associated stilling wells (Figure 1).
At the locations of the well clusters surrounding Red Cove, vertical hydraulic gradients (Tables 3
and 4), calculated using the measured differences in hydraulic head and the vertical distance
between the screen mid-points of wells screened at the water table and at the bottom of the
unconsolidated materials, were generally low in magnitude and predominantly either neutral or
upward during each monitoring event further indicating the potential for discharge to the cove.
The hydraulic head differences between shallow sediments, as measured in the cove piezometers,
and the pond, as measured in the attached stilling wells, were determined at two of the locations
(Figure 19) on April 26, 2007, and at the majority of the locations on September 11/12 (Figure
20) and November 6, 2007 (Figure 21). The hydraulic head differences (Table 5) and the
potential directions of water flow were calculated using the measured differences in groundwater
and surface water elevations at each location. The differences in magnitudes of the hydraulic
gradients between different locations may not be significant due to the shallow depth of
piezometer placement and the difficulties in accurately estimating the elevation of the top of
sediments at each location. Therefore, the magnitude of the hydraulic gradient was not
calculated. In general, the potential directions of groundwater flow indicated by the cove
piezometers are in good agreement with the detailed potentiometric surfaces produced from
April, September, and November groundwater elevation data, generally indicating a potential for
upward flow in areas where the potentiometric surface indicates flow toward the pond and vice
versa.
2.3 Hydraulic Conductivity Structure
The hydraulic conductivity structure near Red Cove was estimated using pneumatic slug testing
techniques in the five well clusters surrounding the cove (Figure 18). The well clusters were
designed to provide complete vertical coverage of the saturated overburden from the water table
to the bottom of the unconsolidated materials. The tests were conducted using procedure
RSKSOP-256. This procedure is based on recommendations derived from Butler (1997). The
procedure utilizes air pressure and vacuum to initiate instantaneous changes in head within the
well combined with high frequency monitoring of the aquifer response using data loggers and
pressure transducers. The aquifer response data were analyzed using the methods of Bouwer and
Rice (1976) and Springer and Gelhar (1991).
Results (Figures 22, 23, 24, 25, and 26) indicate that the hydraulic conductivity at each of these
locations is generally moderate to high. The average hydraulic conductivity in each profile
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ranges from approximately 30 ft/d at RSK36-43 to approximately 80 ft/d at RSK8-12. With the
exception of well cluster RSK3 6-43, the horizontal hydraulic conductivity structure was
relatively uniform as measured on a 5 ft vertical basis, varying only within a factor 2 to 5 at each
location. However, the conductivity structure appears to be more heterogeneous at cluster
RSK36-43 varying by more than an order of magnitude within the vertical profile.
The hydraulic conductivity structure estimated at each location was compared with geologic logs
from nearby wells at the three locations where such logs (Appendix C) were available (RSK1-7,
RSK13-15, and RSK36-43). Detailed comparisons between the lithology logged in borings and
the hydraulic conductivity structure were not possible since the borings were logged using a 1.5
ft split spoon sample obtained every five vertical feet and sample recoveries were generally
moderate to poor. It should also be noted that relatively small differences in hydraulic
conductivity are generally not reliably observable in the geologic logs often obtained at normal
sites (Young et a/., 1998) due to a variety of factors, including the limited coverage of the
vertical profile, poor sample recovery, and the quality/detail of the sample descriptions.
At boring N2, located approximately 50 ft from RSK1-7, the majority of the samples were
logged as fine sands (USCS classification SP) with small differences in the percentage of fine-
grained materials. In addition, a single thin interval of silty sand (USCS classification SM) was
logged within the interval equivalent to the screened zone of the RSK1-7 cluster. However, the
elevation of this interval corresponds to an interval for which no reliable estimates of hydraulic
conductivity were obtained. Therefore, direct comparison is not possible. With the exception of
the silty sand interval, the lithologic log indicates the materials are not highly heterogeneous,
which supports the interpretation of the hydraulic conductivity structure at RSK1-7 (Figure 22).
In similar fashion, the geologic log for boring SEA-4, adjacent to well cluster RSK13-15,
indicates the materials are relatively homogeneous and are predominantly logged as fine to
coarse sands with varying percentage of gravel. A single interval of silty sand with an estimated
thickness of approximately 1.5 ft was logged immediately above the bedrock. This again
supports the interpretation that the hydraulic conductivity structure is not highly heterogeneous at
well cluster RSK13-15 (Figure 24) as measured on a 5 ft vertical interval.
In contrast, the degree of heterogeneity observed in the hydraulic conductivity structure at well
cluster RSK36-43 is not readily discernible from the geologic log for well N3, located
approximately 50 ft away. All intervals above bedrock at N3 were logged as clean sands with an
USCS classification of SP. Two intervals in the lower portion of the section contained
significant gravel. The hydraulic conductivity structure obtained from the RSK36-43 well
cluster indicates that the hydraulic conductivity in the lower 15 ft of the unconsolidated materials
is less than that of the materials near the water table by a factor of approximately 20. Although
this degree of heterogeneity is not readily discernible from the geologic log for N3, it is noted
that the log does indicate that samples in the lower portion of the unconsolidated aquifer
contained some additional fine-grained materials as compared with the samples obtained near the
water table. In general, the percentage of fine-grained materials is often a significant control on
hydraulic conductivity. An increased percentage of fines can result in a significant reduction in
hydraulic conductivity. It is also possible that the geologic materials at RSK36-43 are somewhat
different from those logged at N3 which is 50 ft away. It should be noted that two wells in the
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RSK36-43 cluster were screened over the interval from approximately 205 ft to 210 ft AMSL.
The hydraulic conductivities estimated for materials adjacent to those wells, 3.3 ft/d at RSK39
and 4.6 ft/d at RSK42, were quite similar, indicating that the estimated reduction in hydraulic
conductivity with increasing depth at this location is likely representative of actual conditions.
2.4 Groundwater and Arsenic Flux
Based on the differences in hydraulic gradients measured in April, September, and November, it
is anticipated that groundwater flux and the associated flux of arsenic through the overburden
near Red Cove is temporally variable. Overburden groundwater and arsenic fluxes to Red Cove
were estimated for conditions observed on April 26 and November 7, 2007. Groundwater flux to
Red Cove was estimated using a flow net approach (Cedergren, 1989) whereby flow lines are
constructed using the potentiometric surface for each date for which flux is estimated.
Groundwater flux was then calculated between the bounding flow lines ending at Red Cove. In
this fashion, the flux of groundwater passing a series of vertical planes immediately upgradient
of Red Cove and oriented perpendicular to the direction of flow is estimated. Inputs to the
calculations are the saturated overburden thickness, hydraulic gradients in each area, hydraulic
conductivity structure, and distance perpendicular to flow over which these inputs are assumed to
be representative.
For purposes of this estimation, the potentiometric surface was divided into segments using flow
lines indicating flow to Red Cove within the area encompassed by the network of well clusters
(Figure 27). The segments were chosen to correspond to the midpoints of the distance between
each well cluster and generally correspond with areas of similar hydraulic gradient. The
saturated overburden thickness was estimated at each of the well cluster locations as the
difference between the elevations of drilling refusal and the water table. Saturated thickness
ranged from 15 ft at the RSK13-15 cluster to 32 ft at the RSK1-7 cluster. Since detailed data
regarding bedrock topography were not available for the areas immediately west and south of
Red Cove and the estimated bedrock topography available from previous investigations varies
significantly in this area, the saturated thickness within each segment was assumed equal to the
saturated thickness measured at the well cluster within that segment. Additional study would be
required to obtain a more rigorous estimate of the bedrock surface in the area where this
preliminary estimate of groundwater and arsenic flux was performed.
With the exception of the segment encompassing flow through the vicinity of cluster RSK36-43,
hydraulic conductivity within each segment was assumed to be the average measured for the well
cluster within that particular segment due to the relatively low degree of heterogeneity observed
within each vertical profile. Based on the increased heterogeneity observed at cluster RSK36-43,
the hydraulic conductivity structure in this area was represented by a two-layer system. The top
layer, which was 8 ft thick, was assigned the average hydraulic conductivity estimated for the
upper two wells in the cluster and the bottom layer, which was 15 ft thick, was assigned the
average value for the deepest three wells in the cluster.
The hydraulic gradient was calculated near the center of each segment and immediately
upgradient of the well cluster representative of that segment. Hydraulic gradients in this area
were more stable than in areas immediately adjacent to the pond due, at least in part, to the
decreasing significance of the vertical component of flow with increasing distance from the
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discharge point. Groundwater flux was then calculated (Table 6) as the saturated thickness times
the segment width, hydraulic conductivity, and hydraulic gradient.
The flux of arsenic dissolved in groundwater was estimated using the groundwater flux
calculated for each segment and the concentration of dissolved arsenic in filtered samples
obtained from the well clusters on various dates between October 2006 and November 2007 and
analyzed using ICP-MS methodology. Arsenic flux through each segment was then estimated by
multiplying the groundwater flux by the average dissolved arsenic concentration.
Assumptions inherent in these calculations include:
Groundwater flow is horizontal in the area where fluxes are estimated,
Groundwater from the entire saturated thickness of overburden discharges to the pond,
Assumed values for saturated thickness, hydraulic conductivity, and dissolved arsenic
concentration are representative of relatively large areas surrounding Red Cove, and
Dissolved arsenic concentrations are constant through time.
In all likelihood, none of these assumptions are fully met in the study area. Significant
uncertainty exists with respect to several of these assumptions, particularly the saturated
overburden thickness, hydraulic conductivity distribution, and temporal behavior of arsenic
concentrations. It is also noted that this analysis does not directly evaluate the potential for
discharge to the pond from bedrock. Therefore, these estimates should be considered to be
preliminary in nature and useful only in a comparative sense for understanding the factors that
may influence flux.
As indicated in Table 6, the flux of groundwater and associated arsenic to Red Cove likely was
significantly higher in April 2007 than in November 2007 due to the increased hydraulic
gradients at the time of the measurements in April. It is also interesting to note that the
contribution of arsenic from each area was not uniform. Groundwater moving to the cove in the
vicinity of the RSK1-7, RSK8-12, and RSK16-19 clusters contributed approximately 90% of the
calculated arsenic flux on both April 26 and November 7 while representing approximately 40 %
of the groundwater flow field toward Red Cove. The difference in arsenic flux appears to be
primarily due to the increased arsenic concentrations in these flow paths. Acquisition of
sufficient data to constrain the potentiometric surface under a variety of hydrologic conditions
representative of the full range of conditions observed at this site would be required to better
evaluate the degree to which the current estimates of flux may be representative of "average"
conditions.
2.5 Seepage Measurements
A sensitive bidirectional advective flux meter (Lien, 2006) was used to directly measure the
magnitude and direction of water movement across the sediment/water interface in Red Cove.
The tool was deployed at four locations (Figure 28) to provide direct measurements of water flux
in support of conceptual model development for groundwater/surface water interactions within
the cove. The meter was used to measure fluxes (Table 7) at each of the four locations in April
2007 and also in August and November 2007 at location SM1B.
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Discharge of groundwater into the pond was detected during each measurement. Discharge rates
during August and November were lower than in April. The measured rates in November were
approximately 40% of the discharge rates measured in April. This reduction is in good
agreement with the relative reduction in groundwater flux estimated from the potentiometric
surfaces. The flux estimated using the November 7 potentiometric surface was approximately
35% of that estimated from the potentiometric surface produced for April 26.
Assuming that:
Seepage measurements representative of the area covered by the meter (i.e..,
approximately 2.47 ft) are also representative of the average discharge rate in the cove
and
The area of the cove is approximately 23,000 ft2, as estimated from Figure 1,
then the total discharge of water during the April 24-26, 2007, measurements would have been
approximately 2000 ft3/d. Using the same assumptions, the groundwater discharge to the cove
on November 6 would have been approximately 840 ft3/d. These values compare relatively well
with the estimates of 4300 ft3/d on April 26 and 1500 ft3/d on November 7 obtained using the
modified flow net approach, given the uncertainties in the distribution of discharge to the cove
and the uncertainties in the values of representative parameters for estimation of groundwater
flux from the potentiometric surface data.
2.6 Distribution of Groundwater Discharge to Red Cove
In recent years, the use of heat as a tracer for groundwater movement has been applied to
characterization of groundwater/surface water interactions. In particular, heat has been identified
as a significant tool in characterizing locations and, in some cases, rates of groundwater
discharge to surface water (e.g., Stonestrom and Constantz, 2003; Stonestrom and Constantz,
2004). The temperature history in shallow sediments within areas of groundwater discharge is
often more stable and less influenced by daily and seasonal temperature fluctuations than in areas
without groundwater discharge. Temperature at a depth of 1 ft below the top of sediments was
mapped at approximately one hundred locations within Red Cove and several other points in
adjacent areas of Plow Shop Pond (Figure 3) between October 2006 and September 2007 to aid
in evaluating the potential variability in groundwater discharge within the cove.
In support of this effort, groundwater temperatures in wells screened at the water table were
measured using data loggers at four locations (Figure 29) surrounding Red Cove since
September 2005. Temperatures in the wells screened at the water table (Figure 30) ranged from
approximately 46 deg F to 57 deg F. Groundwater temperatures in wells screened at the bottom
of the unconsolidated materials were also monitored between February and October 2006.
Temperatures in the deeper wells varied within the same range as the shallow wells. For
purposes of this analysis, it is assumed that the temperature range for groundwater discharging to
Red Cove was between 46 deg F and 57 deg F during the period of sediment temperature
records.
At Red Cove, the greatest contrast between surface water and groundwater temperatures occurs
in late winter and, secondarily, again in late summer. For the following analysis, it was assumed
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that the influence of groundwater discharge would result in warmer sediment temperature for
winter and cooler sediment temperature for summer. Sediment temperature on March 20, 2007,
was chosen to be representative of cold weather conditions. Observed temperatures at 8:00 a.m.
varied from approximately 33 deg F to 52 deg F. The data were plotted (Figure 31) to examine
spatial patterns and any correspondence with the range of groundwater temperatures.
Examination of the posted data indicates there is significant spatial variability in sediment
temperatures. Several areas indicate temperatures were within the range of observed
groundwater temperatures while temperature in other areas was much cooler. The areas with the
coolest temperatures are less likely to be areas with significant groundwater discharge. It is also
noted that the areas with the highest temperature were areas with low seasonal variation in
temperature and may represent areas of significant groundwater discharge. In general, the data
indicate that the distribution of groundwater discharge within the cove may be spatially variable.
Sediment temperatures during late summer were also examined as an indicator of the possible
distribution of groundwater seepage. For this purpose, the temperature at noon on August 22,
2007, was chosen to be representative of late summer conditions. Observed temperatures varied
from approximately 49 deg F to 66 deg F. Examination of the posted data (Figure 32) indicates
there is a similar pattern to that observed in the March data set. Several areas indicate
temperatures were within the range of observed groundwater temperatures (46 deg F to 57 deg F)
while temperature in other areas was much warmer. The areas with the warmest temperatures
are less likely to be areas with significant groundwater discharge.
Two of the locations where groundwater seepage was measured using the advective flux meter
(Figure 33) are within areas of warmer, more stable sediment temperatures measured on March
20, 2007, which are potentially indicative of groundwater discharge areas. The remaining two
locations of seepage measurements are adjacent to, but not within, the area where sediment
temperatures were measured. Therefore, no direct comparisons with sediment temperature
patterns can be made. Additional study, including deployment of temperature sensors in the
western portion of Red Cove and expanded use of tools such as the advective flux meter, would
be required to better characterize the range and spatial variability of discharge rates within the
cove.
2.7 Hydrologic Summary
Multiple lines of evidence, including direct measurements using an advective flux meter,
demonstrate that groundwater is currently discharging to Red Cove under most conditions. The
dominant influences on groundwater discharge appear to be:
Precipitation. Periods of increased rainfall may be generally correlated with increased
hydraulic gradients toward the cove and, therefore, increased discharge of groundwater to
the cove.
Pond stage. Hydraulic gradients to Red Cove are often briefly decreased and can reverse
direction during rapid increases in pond stage. In addition, hydraulic gradients may be
significantly reduced during highly elevated stages.
Final Report 30 September 2008 EPA/ORD
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26
Extraction from the SHL pump-and-treat system does not produce readily discernible influences
on hydraulic heads in wells immediately adjacent to Red Cove. Any such effects are likely
masked by the more dominant influences of precipitation and changes in pond stage. However,
the data clearly demonstrate that the current extraction system does not eliminate discharge to the
cove.
Discharge to Red Cove appears to be both spatially and temporally variable in nature.
Additional studies would be required to better characterize the range in both discharge rates and
locations within the cove.
2.8 References
Bouwer, H. and R.C. Rice, 1976. A slug test method for determining hydraulic conductivity of
unconfined aquifers with completely or partially penetrating wells, Water Resources Research,
12:423-428.
Butler, J.J., Jr., 1997. The Design, Performance, and Analysis of Slug Tests, Lewis Publishers.
Cedergren, H.R., 1989. Seepage, Drainage, and Flow Nets, John Wiley & Sons.
CH2MH111, 2006. 2006 annual report, Shepley's Hill Landfill, long-term monitoring &
maintenance, Devens, Massachusetts, CH2MHill, Boston, MA.
Johnson, A.N., B.R. Boer, W.W. Woessner, J.A. Stanford, G.C. Poole, S.A. Thomas, and S.J.
O'Daniel, 2005. Evaluation of an inexpensive small-diameter temperature logger for
documenting ground water-river interactions, Ground Water Monitoring & Remediation, 25:68-
74.
Lien, B.K., 2006. Development and demonstration of a bidirectional advective flux meter for
sediment-water interface, EPA/600/R-06/122, U.S. Environmental Protection Agency,
Cincinnati, OH.
Simeone, R., 2007. E-mail correspondence from Robert Simeone to Ginny Lombardo dated
May 3, 2007.
Springer, R.K. and L.W. Gelhar, 1991. Characterization of large-scale aquifer heterogeneity in
glacial outwash by analysis of slug tests with oscillatory response, Cape Cod, Massachusetts,
U.S. Geological Survey, Water Res. Invest. Rep. 91-4034.
Stonestrom, D.A., and J. Constantz, 2003. Heat as a tool for studying the movement of ground
water near streams, Circular 1260, U.S. Geological Survey, Reston, VA.
Stonestrom, D.A., and J. Constantz, 2004. Using temperature to study stream-ground water
exchanges, Fact Sheet 2004-3010, U.S. Geological Survey, Reston, VA.
Final Report 30 September 2008 EPA/ORD
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27
USEPA, 2008. A systematic approach for evaluation of capture zones at pump-and-treat
systems, EPA/600/R-08/003, U.S. Environmental Protection Agency, Cincinnati, OH.
Young, S.C., H.E. Julian, H.S. Pearson, FJ. Molz, and O.K. Boman, 1998. Application of the
electromagnetic borehole flowmeter, EPA/600/R-98/058, U.S. Environmental Protection
Agency, Cincinnati, OH.
Final Report 30 September 2008 EPA/ORD
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28
Figure 1. Supplemental monitoring network established near Red Cove. Locations of
existing well clusters Nl, N2, and N3 are included for reference. Red triangles mark
groundwater well locations. Yellow dots are the approximate locations of piezometers
within the cove. The blue square marks the location of the Red Cove staff gauge.
Final Report
30 September 2008
EPA/ORD
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29
Piezometer
Stilling Well
Surface Water
Sediments
Figure 2. Schematic diagram of piezometers constructed within Red Cove. Stilling well
is attached only to the piezometer riser.
Final Report
30 September 2008
EPA/ORD
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30
922800
922750
D)
922700
922650
192200 192250
Easting (m)
192300
Figure 3. Locations of the sediment temperature data loggers deployed within Plow Shop
Pond.
Final Report
30 September 2008
EPA/ORD
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4.0 -i
pcf
? X? X?
0.0
Date
Figure 4. Daily rainfall at Fitchburg Municipal Airport during Red Cove study period.
Final Report
30 September 2008
EPA/ORD
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32
75000
CD
fc
v
Date
Figure 5. Daily water discharge from SHL treatment system between August 1, 2006 and
November 30, 2007.
Final Report
30 September 2008
EPA/ORD
-------
33
220.00 -i
219.00
c
B 218.00
TO
>
LU
i_
CD
5 217.00
216.00^
RSK7
RSK12
RSK15
RSK19
RSK37
STAFF1
Increased
Extraction
Rate
1 I
JL
n r
4.0
3.0 j,
0)
2.0 |
5'
1.0 *-
0.0
^
^ ^
#
^
# /
y
,0fo J?
^ o-ฐ
Date
^
^
/
#
^
Figure 6. Comparative plot of rainfall at Fitchburg Municipal Airport, groundwater
elevations at wells RSK7, RSK12, RSK15, RSK19, and RSK37, and surface water
elevations in Red Cove at monitoring point STAFF 1. The date on which the extraction
rate from the SFIL groundwater extraction system was increased to values greater than 40
gal/min is noted for reference.
Final Report
30 September 2008
EPA/ORD
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34
1.2
RSK7-STAFF1
RSK12-STAFF1
RSK15-STAFF1
RSK19-STAFF1
RSK37-STAFF1
2.5 i
^:
l;r
2 0.5
0.0
TJ
219.0 ง.
m
i
218.0 |
3
L- 217.0
CO
j
1,
1
ill!
I
I
Ll
I
J
lu
LJ
I
1
L
1 1 Jl.ll
10/1/06 1/1/07
4/1/07
Date
7/1/07 10/1/07
Figure 7. Hydraulic head differences between wells screened at the water table
immediately adjacent to Red Cove and surface water elevations measured at STAFF 1
compared with pond stage (STAFF 1) and rainfall measured at the Fitchburg Municipal
Airport. The hydraulic head differences are calculated as groundwater elevation minus
surface water elevation. Positive differences signify potential for groundwater flow to
Red Cove (i.e., groundwater discharge to Red Cove). Negative differences signify
potential for surface water flow to the aquifer (i.e., Red Cove recharges the aquifer).
Final Report
30 September 2008
EPA/ORD
-------
219.50
219.00
218.50 -
0)
[[] 218.00 H
cu
217.50
217.00
35
Hydrograph
- STAFF1
RSK7
RSK12
RSK15
RSK19
RSK37
,/ww
8/1/07
9/1/07
10/1/07
11/1/07
Date
Figure 8. Groundwater and surface water elevations during a period of abnormally high
pond stage during the fall of 2007. Points at which the pond briefly recharged the aquifer
during periods of rapid rises in pond elevation are noted by arrows.
Final Report
30 September 2008
EPA/ORD
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36
0.8 i
0.6
(U
o
c
0)
I
?= 0.4
RSK7-STAFF1
RSK12-STAFF1
RSK15-STAFF1
RSK19-STAFF1
RSK37 - STAFF1
9/15/07
9/29/07
10/13/07
Date
10/27/07
11/10/07
Figure 9. Hydraulic head differences between wells screened at the water table
immediately adjacent to Red Cove and surface water elevations measured at STAFF 1
compared with pond stage (STAFF 1) and rainfall measured at the Fitchburg Municipal
Airport during the period of abnormally high pond stage in the fall of 2007. The
hydraulic head differences are calculated as groundwater elevation minus surface water
elevation. Higher hydraulic head differences indicate higher hydraulic gradients.
Positive differences signify potential for groundwater flow to Red Cove (i.e.,
groundwater discharge to Red Cove). Negative differences signify potential for surface
water flow to the aquifer (i.e., Red Cove recharges the aquifer).
Final Report
30 September 2008
EPA/ORD
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37
CO
219.50
219.00
218.50 -
c
'B 218.00 H
CD
LU
CD
217.50 -
217.00 -
216.50 -1
10/1/06 1/1/07 4/1/07 7/1/07 10/1/07
Date
Figure 10. Comparative plot of daily water discharge from the SHL treatment system,
groundwater elevations at wells surrounding Red Cove, and surface water elevations in
Red Cove measured at monitoring point STAFF 1 for the period August 2006 to
November 2007.
Final Report
30 September 2008
EPA/ORD
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38
2T 218.50
CO
G. 218.00
c
,g
'ซ>
03
ฎ 217.50 H
LJJ
S 217.00
ir-
ro
S
g, 80000
ra 60000
o 40000 -
jJ5 20000 -
fe 0
r- 1.50 7J
B)
- 1.00 =
ฃD
0.50 =
0.00 ^.
7/13/07
7/17/07
7/21/07
Date
7/25/07
7/29/07
Figure 11. Comparative plot of daily water discharge from the SHL treatment system,
rainfall, groundwater elevations at wells immediately adjacent to Red Cove, and surface
water elevations in Red Cove measured at monitoring point STAFF 1 for the period July
13-30,2007.
Final Report
30 September 2008
EPA/ORD
-------
39
SHM-99-31AI
213.5
SHM-99-31B
^ 212.4
SHM-99-31C
SHP-99-33A
212.5
SHP-99-33B
212.4
SHM-05-39A
212.1
SHP-05-49A
212.5
SHP-05-49B
212
SHP-05-48B
213.6
SHM-05-42A-
214.2
SHM-C5-42B
214.2'
SHM'-05-41B
214,2
SHM-05-41C
214.3
SHM-96-5C (
A 214.8 Si
fW-04
1 NM
5W.-01 pilot
214.9
N-2, P-1
217.4
K3.P-2
217.1
SHP-01-38A--.
217.8
= Bedrock {Screened
Estimated Grojndwater Bevatbn Contajr
Sssfwc i*fire!rfcrrcc; r ^-fitaowe rMnseatevcl
SHL-15 Location ID
243.5 * Groundwater Elevation
Weii cr Piezometer
Figure 4-2
Contour Map of Groundwater Elevations
on December 1S, 2006
Extraction Well
- = !rst1jne"r' Error
or Under Water)
PiVL = Perched W aer Level
'rV'j _ = S j tfjt* ^ as r Level Sbepte/s Hill L
Ccntour Internal = 1 foot (axcept where explidty labesed)
ft1"'. Fo.^ Deh/erco. IVM
.CH2MHILL
Figure 12. Site-wide contour map of groundwater elevations on December 15, 2006,
provided in the 2006 annual report (CH2MHill, 2006).
Final Report
30 September 2008
EPA/ORD
-------
40
219.50
219.00
(f)
ฃ. 218.
c
o
'-tป
03
jjj 218.
217.50
217.00
Hydrograph
- RSK7
- RSK12
RSK15
RSK19
- STAFF 1
Rainfall
Potentiometric
Surface
Figure 13. Detailed comparison of groundwater elevations in wells surrounding Red
Cove, surface water elevations measured at STAFF 1, and rainfall at Fitchburg Municipal
Airport between April 8 and 26, 2007. The point in time at which water level
measurements were made for creation of a potentiometric surface is also depicted.
Final Report
30 September 2008
EPA/ORD
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41
220.00
219.00
C/)
-4= 218.00
5
JD
LJJ
i_
-------
42
922900
922600
192100
192150
192200
192250
192300
Easting (m)
Figure 15. Potent!ometric surface on April 26, 2007, produced using existing shallow
wells and enhanced RSK network. Wells are depicted by red triangles and the surface
water monitoring point is depicted by a blue square. Well names were generally omitted
to improve figure clarity. Groundwater elevation contours are depicted in units of feet
with a contour interval of 0.2 ft. The approximate location of the groundwater divide
separating flow toward Red Cove and the western portion of Plow Shop Pond from flow
toward the extraction system is depicted as a dashed magenta line.
Final Report
30 September 2008
EPA/ORD
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43
922850
922800
922750
O 922700
922650
922600
192100
192150 192200 192250
192300
Easting (m)
Figure 16. Potent!ometric surface on September 10, 2007, produced using shallow
existing wells and enhanced RSK network. Wells are depicted by red triangles and the
surface water monitoring point is depicted by a blue square. Well names were generally
omitted to improve figure clarity. Groundwater elevation contours are depicted in units
of feet with a contour interval of 0.2 ft. The approximate location of the groundwater
divide separating flow toward Red Cove and the western portion of Plow Shop Pond
from flow toward the extraction system is depicted as a dashed magenta line.
Final Report
30 September 2008
EPA/ORD
-------
44
922900
922850
922800
D)
922750
922700
922650
922600
192100 192150 192200 192250 192300
Easting (m)
Figure 17. Potent!ometric surface on November 7, 2007, produced using shallow
existing wells and enhanced RSK network. Wells are depicted by red triangles and the
surface water monitoring point is depicted by a blue square. Well names were generally
omitted to improve figure clarity. Groundwater elevation contours are depicted in units
of feet with a contour interval of 0.2 ft. The approximate location of the groundwater
divide separating flow toward Red Cove and the western portion of Plow Shop Pond
from flow toward the extraction system is depicted as a dashed magenta line.
Final Report
30 September 2008
EPA/ORD
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45
922750
922700
922650
192150
192200
192250
Easting (m)
Figure 18. Well clusters used for determination of vertical hydraulic gradients and
hydraulic conductivity structure.
Final Report
30 September 2008
EPA/ORD
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46
922900
922600
192100 192150 192200 192250 192300
Easting (m)
Figure 19. Potent!ometric surface on April 26, 2007, and locations of lake-bed
piezometers in which hydraulic heads were measured in comparison to the pond level at
the same location. Yellow dots indicate piezometer locations at which the potential
direction of flow was from the sediments to the surface water (i.e., upward). Wells are
depicted by red triangles and the surface water monitoring point is depicted by a blue
square. Well names were generally omitted to improve figure clarity. Groundwater
elevation contours are depicted in units of feet with a contour interval of 0.2 ft.
Final Report
30 September 2008
EPA/ORD
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47
922850
922800
922750
922700
922650
922600
192100
192150 192200 192250
192300
Easting (m)
Figure 20. Potent!ometric surface on September 10, 2007, and locations of lake-bed
piezometers in which hydraulic heads were measured in comparison to the pond level at
the same location. Yellow dots indicate piezometer locations at which the potential
direction of flow was from the sediments to the surface water. Magenta dots indicate
piezometer locations at which the potential direction of flow was from the surface water
to the sediments (i.e., downward). Green dots indicate locations where the gradient was
considered to be insignificant (i.e., no discernible flow direction). Wells are depicted by
red triangles and the surface water monitoring point is depicted by a blue square. Well
names were generally omitted to improve figure clarity. Groundwater elevation contours
are depicted in units of feet with a contour interval of 0.2 ft.
Final Report
30 September 2008
EPA/ORD
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48
922900
922850
1-36X
'
E,
D)
922800
922750
922700
922650
922600
192100
192150 192200 192250 192300
Easting (m)
Figure 21. Potent!ometric surface on November 7, 2007, and locations of lake-bed
piezometers in which hydraulic heads were measured in comparison to the pond level at
the same location. Yellow dots indicate piezometer locations at which the potential
direction of flow was from the sediments to the surface water. Magenta dots indicate
piezometer locations at which the potential direction of flow was from the surface water
to the sediments (i.e., downward). Green dots indicate locations where the gradient was
considered to be insignificant (i.e., no discernible flow direction). Wells are depicted by
red triangles and the surface water monitoring point is depicted by a blue square. Well
names were generally omitted to improve figure clarity. Groundwater elevation contours
are depicted in units of feet with a contour interval of 0.2 ft.
Final Report
30 September 2008
EPA/ORD
-------
49
220-1
210-
CO
c
g
"ro
_0
LU
200-
190-
180
Water Table
No Data
Geoprobe Refusal
i i i i i i i i i i i i i i r
0
25 50 75
Hydraulic Conductivity (ft/d)
100
Figure 22. Hydraulic conductivity profile at well cluster RSK1-7.
Final Report
30 September 2008
EPA/ORD
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50
220 ^
210-
co
c
g
"ro
_0
LU
200^
190-
180
0
Water Table
Geoprobe Refusal
\ i r
T
\ \
\ i i r
T
i r
25 50 75
Hydraulic Conductivity (ft/d)
100
Figure 23. Hydraulic conductivity profile at well cluster RSK8-12. Analyses represent
updated solutions relative to the preliminary estimates provided in the previous interim
report.
Final Report
30 September 2008
EPA/ORD
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51
220 ^
210-
CO
c
g
"ro
_0
LU
200^
190-
180
Water Table
Geoprobe Refusal
i i i i i i i i i i i i i i r
0
25 50 75
Hydraulic Conductivity (ft/d)
I
100
Figure 24. Hydraulic conductivity profile at well cluster RSK13-15.
Final Report
30 September 2008
EPA/ORD
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52
220 ^
210-
CO
c
g
"ro
_0
LU
200^
190-
180
Water Table
Geoprobe Refusal
i i i i i i i i i i i i i i r
0
25 50 75
Hydraulic Conductivity (ft/d)
I
100
Figure 25. Hydraulic conductivity profile at well cluster RSK16-21.
Final Report
30 September 2008
EPA/ORD
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53
220 ^
210-
CO
c
g
"ro
_0
LU
200^
190-
180
0
Water Table
Geoprobe Refusal
i i i i i i i i i i i i i i r
25 50 75
Hydraulic Conductivity (ft/d)
I
100
Figure 26. Hydraulic conductivity profile at well cluster RSK36-43.
Final Report
30 September 2008
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54
922800
922750
O)
.E 922700
tr
O
922650
922600
192100
[Segment g
^egment4| [Segment
192150 192200 192250
192300
Easting (m)
Figure 27. Potentiometric surface on November 7, 2007, and typical example of
flowpaths used in estimation of groundwater and dissolved arsenic flux. Well clusters
used in flux calculations are depicted as red triangles. Groundwater elevation contours
are depicted in units of feet with a contour interval of 0.2 ft.
Final Report
30 September 2008
EPA/ORD
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55
922750
O)
c
922700-
922650
192150 192200 192250
Easting (m)
192300
Figure 28. Approximate locations of seepage measurements made using an advective
flux meter (green diamonds).
Final Report
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56
922750
922700
D)
922650
192150
192200
192250
Easting (m)
Figure 29. Locations of wells screened at the water table where groundwater
temperatures were measured using data loggers.
Final Report
30 September 2008
EPA/ORD
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57
60.0^
-g 56.0 H
S
I
E 52.0 -
(D
T3
C
13
O
O
48.0
44.0
Legend
RSK7
RSK12
RSK15
RSK19
Date
Figure 30. Groundwater temperature measured using data loggers in wells screened at
the water table surrounding Red Cove.
Final Report
30 September 2008
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58
922900
922850
922800
922750
922700
922650
Potential for
Discharge
* High
Medium
Low
Negligible
192100 192150 192200 192250 192300
Easting (m)
Figure 31. Classed posting map of sediment temperatures at 8:00 a.m. on March 20,
2007 (groundwater temperature range was 49-51 deg F). Temperatures were classed
using the following ranges: Red (48 deg F to < 52 deg F), Yellow (46 deg F to < 48 deg
F), Blue (40 deg F to < 46 deg F), and Purple (33 deg F to < 40 deg F). Wells N1,P3;
N2,P2; and N3,P2 are plotted (red triangles) for reference.
Final Report
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59
922900
922850
922800
922750
922700
922650
Potential for
Discharge
High
Medium
Low
Negligible
192100 192150 192200 192250 192300
Easting (m)
Figure 32. Classed posting map of sediment temperatures at noon on August 22, 2007
(groundwater temperature range was 50-53 deg F). Temperatures were classed using the
following ranges: Red (49 deg F to < 53 deg F), Yellow (53 deg F to < 55 deg F), Blue
(55 deg F to < 60 deg F), and Purple (60 deg F to < 66 deg F).
Final Report
30 September 2008
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60
922750
O)
.E 922700
922650
Potential for
Discharge
High
Medium
Low
Negligible
192200 192250
Easting (m)
192300
Figure 33. Zoomed portion of classed posting map of sediment temperatures at 8:00 a.m.
on March 20, 2007 in Red Cove (groundwater temperature range was 49-51 deg F).
Temperatures were classed using the following ranges: Red (48 deg F to < 52 deg F),
Yellow (46 deg F to < 48 deg F), Blue (40 deg F to < 46 deg F), and Purple (33 deg F to
< 40 deg F). Locations where the advective flux meter was deployed in Red Cove are
plotted as white diamonds. Wells N2,P2 and N3,P2 are plotted (red triangles) for
reference.
Final Report
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61
Table 1. Average groundwater elevations in shallow wells surrounding Red Cove
compared to surface water elevations measured at STAFF1 for the period August 2,
2006 to November 7, 2007.
Monitoring
Location
RSK7
RSK12
RSK15
RSK19
STAFF 1
Water Elevation
(ft AMSL)
217.40
218.16
218.02
217.68
217.29
Groundwater Elevation
Minus
Surface Water Elevation *
(ft)
0.11
0.87
0.73
0.39
* Positive differences in elevations indicate a potential flow direction toward the pond.
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62
Table 2. Average groundwater elevations in shallow wells surrounding Red Cove
compared to surface water elevations measured at STAFF1 for the period October 4
to October 19, 2007.
Monitoring
Location
RSK7
RSK12
RSK15
RSK19
RSK37
STAFF 1
Water
Elevation
(ft AMSL)
218.38
218.61
218.55
218.42
218.41
218.37
Groundwater Elevation
Minus
Surface Water Elevation *
(ft)
0.01
0.24
0.18
0.05
0.04
* Positive differences in elevations indicate a potential flow direction toward the pond.
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63
Table 3. Vertical hydraulic gradients at well clusters surrounding Red Cove in
2005/2006.
Well
RSK7
RSK1
RSK19
RSK16
RSK12
RSK8
RSK15
RSK13
9/15/05
Groundwater
Elevation
(ft AMSL)
217.14
217.17
217.35
217.39
217.76
217.77
217.62
217.63
iv
0.003
0.003
NS
NS
8/2/06
Groundwater
Elevation
(ft AMSL)
217.27
217.38
217.60
217.66
218.05
218.01
iv
0.011
0.004
-0.004
10/19/06
Groundwater
Elevation
(ft AMSL)
217.42
217.50
217.65
217.70
218.03
218.05
217.90
217.91
iv
0.008
0.003
NS
NS
Note: Positive vertical hydraulic gradient (iv) indicates potential for upward flow.
NS = Not Significant. The hydraulic head difference was less than 0.02 ft.
Final Report
30 September 2008
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64
Table 4. Vertical hydraulic gradients at well clusters surrounding Red Cove in
2007.
Well
RSK7
RSK1
RSK19
RSK16
RSK12
RSK8
RSK15
RSK13
RSK37
RSK41
4/26/07
Groundwater
Elevation
(ft AMSL)
217.65
217.76
217.97
218.01
218.59
218.58
218.56
218.57
217.76
217.81
iv
0.011
0.004
NS
NS
0.005
11/7/07
Groundwater
Elevation
(ft AMSL)
217.95
217.97
218.05
218.09
218.34
218.35
218.27
218.27
217.99
218.00
iv
NS
0.004
NS
NS
NS
Note: Positive vertical hydraulic gradient (iv) indicates potential for upward flow.
NS = Not Significant. The hydraulic head difference was less than 0.02 ft.
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Table 5. Hydraulic head differences between piezometers in Red Cove and surface
water.
Piezometer
PZ1
PZ2
PZ3
PZ4
PZ5
PZ6
PZ7
PZ8
PZ9
PZ10
PZ11
PZ12
Date
9/1 1/07
1 1/6/07
9/1 1/07
1 1/6/07
9/1 1/07
1 1/6/07
9/1 1/07
1 1/6/07
9/1 1/07
1 1/6/07
9/1 1/07
1 1/6/07
9/1 1/07
9/1 1/07
1 1/6/07
9/12/07
1 1/6/07
4/26/07
9/12/07
4/26/07
9/12/07
1 1/6/07
9/12/07
1 1/6/07
Hydraulic Head
Difference *
(ft)
0.25
0.43
0.11
0.07
0.04
0.03
0.01
0.02
0.05
0.08
0.11
0.14
0.07
0.00
0.03
0.04
0.02
0.19
-0.14
0.04
-0.27
-0.26
-0.01
-0.02
Potential Flow
Direction
UP
UP
UP
UP
UP
UP
Not Significant
Not Significant
UP
UP
UP
UP
UP
Not Significant
UP
UP
Not Significant
UP
DOWN
UP
DOWN
DOWN
Not Significant
Not Significant
* Hydraulic head differences were calculated by subtracting the depth to water measured
in the piezometer from the depth to water measured in the stilling well using a common
reference point.
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Table 6. Groundwater and Arsenic Flux Calculated from Potentiometric Surface
Maps.
Date
4/26/07
11/7/07
Well Cluster
RSK1-7
RSK8-12
RSK13-15
RSK16-19
RSK37-41
(shallow)
RSK37-41
(deep)
RSK1-7
RSK8-12
RSK13-15
RSK16-19
RSK37-41
(shallow)
RSK37-41
(deep)
Hydraulic
Conductivity
(ft/d)
67
83
35
66
75
4.4
67
83
35
66
75
4.4
Saturated
Overburden
(ft)
32
27
15
23
8
15
32
27
16
23
8
15
Hydraulic
Gradient
(ft/ft)
0.005
0.006
0.013
0.007
0.011
0.011
Totals
0.002
0.004
0.004
0.003
0.003
0.003
Totals
Water
Flux
(ft3/d)
659
1546
767
1129
744
82
4268
122
662
254
291
243
27
1476
Diss. As
(mg/1)
0.72
0.81
0.26
0.74
0.01
0.34
0.72
0.81
0.26
0.74
0.01
0.34
As Flux
(g/d)
13.4
35.5
5.6
23.7
0.2
0.8
79.2
2.5
15.2
1.9
6.1
0.07
0.3
26.0
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Table 7. Seepage Flow Measured Using a Bidirectional Advective Flux Meter.
Location
SM1A
SM2A
SM2B
SM1B
SM1B
SM1B
Date
4/24/07
4/24/07
4/26/07
4/26/07
8/21/07
1 1/6/07
Seepage Flow
(ftVd)
0.229 +/- 0.060
0.224 +/-0.034
0.197 +/-0.084
0.223 +/-0.039
0.158 +/-0.009
0.091 +/-0.015
Flow Direction
UP
UP
UP
UP
UP
UP
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3 Groundwater Chemistry Studies
The objectives of the groundwater chemistry studies performed at the Fort Devens sediments
research site included determination of the spatial and temporal patterns in arsenic concentrations
adjacent to Red Cove, the chemical speciation of arsenic, and the chemical characteristics of
groundwater for the purpose of delineating potential contributions from groundwater underlying
Shepley's Hill Landfill and defining the conditions supporting arsenic transport. Investigations
included installation of wells adjacent to Red Cove and within the shallow aquifer underlying
sediments within Red Cove. Data and results from these studies are discussed below.
3.1 Monitoring Network
Twenty-six (26) monitoring wells with five-foot screens were installed in the overburden in the
vicinity of Red Cove to facilitate collection of groundwater samples at different depths within the
saturated overburden. Additional details on well construction are provided under the section
entitled Hydrologic Studies. The sampled wells were grouped in five clusters around the
perimeter of Red Cove and are designated RSK 1-7, RSK 16-20, RSK 8-12, RSK 13-15, and
RSK 37-42 (Figure 34). Well clusters RSK 1-7, RSK 16-20 and RSK 37-42 each had two
screens completed at similar depths; RSK 3/6, RSK 17/20, and RSK 39/42, respectively. Except
for well cluster RSK 37-42, each of the well clusters were sampled at least twice during the
period from March 2006 to September 2007 (see Appendices). Sampling at screened interval
RSK 2 in the RSK 1-7 cluster was discontinued due to continual silt accumulation within the
screen. In addition to wells installed below land surface, a network often, short-screened (0.5
foot, stainless steel) well points was installed by hand underneath sediments in Red Cove (Figure
34). These well points were designated RCTW 1-10, and their location relative to surface water
sampling within Red Cove are shown in Figure 34. The RCTW wells were sampled at least
twice during the period March 2006 to September 2007 (see Appendices). Groundwater
chemistry from Wells RCTW 5, RCTW 8 and RCTW 9 are not reported for August 2007 due to
visible evidence of damage and inconsistencies in chemical readings from previous sampling
events and nearby wells. EPA/ORD also collected groundwater samples from Shepley's Hill
Landfill wells N5-P1, N5-P2, SHM-96-22B, and SHM-93-22C on September 13, 2007 for
analysis of dissolved methane (September 15, 2007 Memorandum; Ford to Lombardo-Region 1).
The elevation of well screens that were installed and sampled by EPA/ORD, as well as select
existing wells, is shown in Figure 35. Two cross-sectional views are shown that are generally
aligned along an east-west and north-south transect at Red Cove (see Figure 35), although it
should be noted that these well screens do not lie on a planar transect. These views demonstrate
that EPA/ORD well screens overlap in depth with the depths sampled by existing wells within
the Red Cove Study Area for which historical data are available for comparison.
3.2 Groundwater Chemistry Trends: RSK Wells and Sheplev's Hill Landfill
The vertical distribution of dissolved (0.45 |im filtered) arsenic in groundwater intercepted by
RSK well clusters is shown in Figure 36. Data from all sampling events are shown
independently (Appendix, Tables G.1-G.6), revealing a general consistency in arsenic
concentration at a given depth over the period of observation (March 2006 - September 2007).
Well clusters RSK 1-7, RSK 16-20, and RSK 8-12 all displayed the highest concentrations of
arsenic throughout the saturated depth within the aquifer adjacent to Red Cove. Dissolved
arsenic concentrations ranged from 400-1000 |ig/L (Figure 36). In general, lower concentrations
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of dissolved arsenic, typically less than 400 |ig/L, were observed at well clusters RSK 13-15 and
RSK 37-42. There was distinct stratification in the distribution of dissolved arsenic at well
cluster RSK 37-42, with concentrations <200 |lg/L in the more shallow screened intervals (RSK
37, RSK 38, RSK 39, RSK 42) and >500 |ig/L for the deepest two screened intervals (RSK 40
and RSK 41). These data also indicate that the higher calculated flux of arsenic for the RSK 16-
20 and RSK 8-12 well clusters is attributable to higher concentrations of arsenic in groundwater.
In addition, depth profiles for dissolved arsenic acquired via direct-push sampling by EPA
Region 1 in 2004 are also shown. Based on the reported locations for these sampling locations
(Carol Stein, Gannett-Fleming, Inc.; 12/14/2007 e-mail communication), these data are
referenced to well clusters RSK 16-20 (Region 1 location RC1) and RSK 8-12 (Region 1
location RC2). Depth-discrete data for the RC1 vertical profile are fully consistent with
observations at RSK 16-20. Disparities exist between data collected at RSK 8-12 and RC2,
particularly at mid-depth for these vertical profiles. As a point of reference, historical
concentrations of total arsenic reported by the Army are shown for wells SHL-4, SHL-11, SHL-
20, and SHP-01-38A. These reported values are consistent with observations at similar depths
and location for RSK wells (i.e., SHL-4 and RSK 15; SHP-38A-1 and RSK 12; SHL-20 and
RSK 1; SHL-11 and RSK 7).
Vertical trends for a selection of groundwater chemical parameters for RSK wells are shown in
Figure 37. Patterns in geochemical parameters that may be indicative of microbially-driven
processes are shown for the five RSK well clusters in Figure 38. Alkalinity, as indicated by the
concentration of bicarbonate, is lowest in well clusters RSK 13-15 and RSK 37-42 (generally
<200 mg HCO3/L). In general, well clusters RSK 8-12 and RSK 16-20 have the lowest sulfate
concentrations and highest ammonia-nitrogen concentrations. This contrasts with well cluster
RSK 1-7, which has relatively low concentrations of ammonia-nitrogen and the highest
concentrations of sulfate. The observed microbial signature for groundwater chemistry at well
clusters RSK 8-12 and RSK 16-20 may be due either to microbial activity within the aquifer at
the location of the well screens or due to transport of groundwater that has already been
influenced by microbial activity from upgradient source areas. Patterns in major element
chemistry for RSK wells and a selection of existing wells adjacent to Red Cove (SHL-4, SHL-
11, SHL-20, and SHP-01-38A) and within Shepley's Hill Landfill (south -N7-P1, N7-P2;
central - SHP-99-29X, N5-P1, N5-P2; north - SHL-9, SHL-22, SHM-93-22C, SHM-96-22B)
are represented by concentrations of chloride, sodium, and potassium in Figure 38 (See Figure 12
for well locations within Shepley's Hill Landfill.). In general, the salt content reflected by these
chemical parameters is higher in EPA/ORD well clusters RSK 1-7, RSK 16-20, and RSK 8-12
compared to that observed at RSK 13-15 and RSK 37-42, but all well screen compositions
appear to fall along a general linear trend. The salt content in existing wells adjacent to Red
Cove is comparable for similar screen depths (i.e., SHL-4, SHL-11, SHL-20, and SHP-01-38A).
Salt content for existing wells installed within the landfill generally fall within the range
observed at RSK wells. Whereas the trend for Na-Cl composition is very similar for RSK and
landfill wells, there appears to be some disparity between the potassium concentration for well
N5-P2 installed across the water table within the central portion of the landfill.
Comparison of groundwater arsenic concentrations as a function of iron, calcium, and
bicarbonate are shown in Figure 39 for RSK wells and several existing wells within or just north
of Shepley's Hill Landfill (south - N7-P1, N7-P2; central - SHP-99-29X, N5-P1, N5-P2; north -
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SHL-9, SHL-22, SHM-93-22C, SHM-96-22B) and adjacent to the Red Cove Study Area (SHL-
4, SHL-11, SHL-20, and SHP-01-38A). These data demonstrate that there is concurrence
between historical and contemporary measurements of groundwater chemistry for existing wells
adjacent to Red Cove that are in close proximity to RSK wells (i.e., SHL-4 and RSK 15; SHP-
01-38A and RSK 12; SHL-20 and RSK 1; SHL-11 and RSK 7). These data also reveal some
disparity in groundwater chemistry observed in existing wells installed within Shepley's Hill
Landfill and RSK wells adjacent to Red Cove. Groundwater chemistry at the N7-P1,P2
piezometer cluster appears to be similar to that observed at RSK 13-15 and the shallowest four
screen intervals at RSK 37-42. Inspection of the piezometric surface determined for the landfill
on December 15, 2006 (Figure 12) indicates the potential for groundwater flow from the location
of N7-P1,P2 to a portion of the aquifer screened by well clusters RSK 13-15 and RSK 37-42
adjacent to Red Cove. Examination of groundwater chemistry data for existing wells within the
central and northern portions of the landfill indicates disparity in groundwater chemistry relative
to that observed at RSK wells. Within the central portion of the landfill, arsenic appears to be
highest near the bottom of the aquifer (e.g., N5-P1 and SHP-99-29X) and exceeds the
concentration of arsenic in groundwater adjacent to Red Cove by a factor of three to four. The
elevation at which the highest arsenic concentration is observed at piezometer pair N5 (-145 ft
AMSL) coincides with the elevation of highest arsenic concentration observed in wells located
immediately down gradient of the groundwater extraction system (see well SHM-93-22B; Figure
39). It is also evident that chemical conditions vary dramatically as a function of depth in the
central portion of the landfill, as reflected by the concentration of bicarbonate and calcium
observed at N5-P1 (deep) and N5-P2 (shallow). The concentration of these two constituents is
higher near the water table where arsenic concentration is approximately two orders-of-
magnitude lower (compare N5-P2 and N5-P1).
In order to better understand these disparities in groundwater chemistry through the saturated
thickness of the aquifer, vertical trends in groundwater chemistry for the central and northern
portions of the landfill were examined in relation to observations adjacent to Red Cove. This
analysis was conducted to assist interpretation of the potential relationships (or lack thereof)
between elevated arsenic observed within the landfill and the Red Cove Study Area. Vertical
trends in potassium and arsenic are shown for several screened intervals within the landfill and
RSK wells in Figure 40. For the central portion of the landfill, the aquifer is screened near the
water table (N5-P2, SHP-99-29X) and within bedrock (N2-P1) with approximately 60 feet of
saturated aquifer thickness not being sampled. Beyond the northern portion of the landfill, there
is a selection of wells that provide reasonable coverage of the entire saturated thickness (SHL-5,
SHL-9, SHM-96-5C, SHM-93-22B, SHM-96-5B, and SHL-22) including bedrock (SHM-93-
22C). It should be noted that the well screens listed beyond the northern portion of the landfill
are not a true cluster of well screens. The aerial distribution of these well locations falls within a
circle with an approximate diameter of 60 meters (Figure 40, middle panel). Potassium was
chosen as a point of reference relative to groundwater transport, and patterns for this constituent
(Figure 40, left panel) were then compared to that observed for arsenic (Figure 40, right panel).
The concentrations of potassium and arsenic observed at RSK wells fall within the range of
concentrations observed at wells located within the landfill. Existing wells representative of the
southern portion of the landfill (i.e., represented by wells SHL-15, N7-P2, N7-P1 located
southwest of Red Cove) show observed potassium and arsenic concentrations that are lower than
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observed concentrations at EPA/ORD well clusters RSK 8-12, RSK 16-20, and RSK 1-7. There
is general correspondence with concentrations of these elements observed at EPA/ORD well
clusters RSK 13-15 and RSK 37-42. The concentrations of these constituents are generally
lower just beyond the northern portion of the landfill across the saturated thickness
corresponding to screen depths at Red Cove (specifically EPA/ORD well clusters RSK 8-12,
RSK 37-42, RSK 1-7; approximate elevation >185 ft AMSL). Finally, concentrations of these
constituents within the central portion of the landfill bracket observations at the RSK well
clusters. In order to capture the potential influence of the groundwater P&T system on these
observations, the time trend in potassium and arsenic concentrations during 2006 and part of
2007 just beyond the north portion of the landfill is included in Figure 40. For potassium there
appears to be a slight decrease in concentration over the screened depth based on comparison of
the mean and standard deviation for the entire data set (January 2006 - October 2007;
CH2MHill, 2006; Ginny Lombardo, 12/21/2007 e-mail correspondence) compared to that
observed during October 2007 alone (Figure 40, left panel). This same general trend is also
apparent for arsenic concentrations observed across the same depth interval, although it is
unclear if this is due to ongoing groundwater extraction or seasonal influences in groundwater
flow or chemistry. It should be noted that the maximum concentration of potassium occurs at a
shallower depth (-165 ft AMSL) than the maximum arsenic concentration (-145 ft AMSL).
One possible source of arsenic in groundwater may be derived from dissolution of natural forms
of arsenic present in site soils due to association with iron-bearing minerals such as iron oxides
or iron sulfides (Gannett Fleming, 2006). Since there appears to be a general increase in the
concentration of arsenic and iron in groundwater from the southern to northern extent of the
landfill, calculations were carried out to estimate to what extent this could be attributed to
dissolution of site soils. Background soil composition data used to calculate potential ranges of
arsenic and iron that could be generated by soil dissolution were taken from the 1993 RI
Addendum. For the purpose of calculation, it was assumed that dissolution of soil iron resulted
in release of arsenic at a ratio equivalent to that in the soil material. Subsequently, an equivalent
arsenic concentration in groundwater was determined for a range of iron concentration that
encompassed the range of iron observed in site groundwater (Shepley's Hill Landfill and Red
Cove Study Area). The results of these calculated ranges are shown in Figure 41 (left panel)
along with groundwater data for RSK wells and existing wells representative of the south (NT-
PI, N7-P2, SHL-15) and central (SHP-99-29X, N5-P1, N5-P2) portions of the landfill. The
range of possible As-Fe compositions derived from congruent dissolution of all site-derived soils
(including compositional outliers) is inclusive of compositions estimated from aquifer fines
recovered during development of well screens RSK 2 and RSK 37 (Table 8). Some of the
groundwater compositions observed at well cluster RSK 37-42, RSK 13-15, and the north
portion of the landfill (SHL-15, N7-P1, N7-P2) could be reasonably explained by the process of
soil dissolution. The composition at well screen N5-P2 also falls within the range bracketed by
estimated soil contributions, although it should be noted that this calculation approach ignores
potential chemical factors (e.g., redox) that could alter the As:Fe ratio in groundwater. In
contrast, arsenic concentrations observed in groundwater at well clusters RSK 8-12, RSK 16-20,
and RSK 1-7 are significantly higher than that attributable to dissolution of a background soil
source. This observation suggests a source of arsenic other than that attributable to shallow
background soils. As seen in previous data presentations, the groundwater compositions
observed at RSK well clusters with highest arsenic concentrations are bracketed by groundwater
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compositions from wells SHP-99-29X (or N5-P1) and N5-P2. This suggests the possibility that
groundwater compositions observed at EPA/ORD well cluster RSK 8-12 (saturated thickness
-25 feet) may be due to converging groundwater flow lines moving from a portion of the landfill
west-southwest of Red Cove where the saturated thickness is approximately 70 feet.
In order to illustrate the concept of converging groundwater flow lines, a cross-section through
the aquifer through existing well locations SHP-99-29X and SHL-4 is shown in Figure 42
(bottom panel; approximate locations of RSK 8-12 and RSK 13-15 also shown). An aerial view
of these well locations, along with RSK well clusters (color coded), is shown in the top left-hand
panel of Figure 42. Based on the calculated potentiometric surface for site groundwater (Figure
12; CH2MHill, 2006), there is no hydrologic evidence to support flow from the portion of the
landfill and aquifer screened at locations SFIP-99-29X or N5-P1,P2 to groundwater observed to
discharge into Red Cove. However, given the lack of alternative locations within the landfill
with available chemistry data, estimates of possible groundwater mixing due to converging flow
lines must rely on the available contemporaneous data from within the boundary of Shepley's
Hill Landfill. Employing observed concentrations of potassium and arsenic at well cluster RSK
8-12 during September 2007, relative mixtures of groundwater from SHP-99-29X & N5-P2 or
N5-P1 & N5-P2 can be estimated. Assuming a simplified binary mixture of waters and
conservative transport for arsenic or potassium, mixing estimates are shown below. (Note that
groundwater from N5-P2 must be included in order to achieve potassium concentrations
observed at RSK 8-12.) These calculations should only be viewed as a preliminary estimate of a
potential source of the groundwater composition observed at RSK well clusters with highest
arsenic concentrations. However, these estimates indicate that a mixture of groundwater sources
originating from upgradient portions of the landfill could reasonably represent the chemical
characteristics of groundwater discharging into Red Cove.
RSK 8-12
Sept 2007
Avg. Composition
734 ng As/L
13.1mgK/L
Binary Mixture #1
SHP-99-29X
2953 |ig As/L
0.6 mg K/L
24%
39%
N5-P2
29.6 |ig As/L
21mgK/L
76%
61%
Binary Mixture #2
N5-P1
4451 |igAs/L
5.9mgK/L
16%
52%
N5-P2
29.6 |ig As/L
21mgK/L
84%
48%
Trends in the concentrations of ammonia (as NHs-N; 2006-2007 period) and methane
(September 2007) observed at RSK well clusters support the potential influence of solid waste
degradation on groundwater chemistry (Figure 42; upper right-hand panel). There is a general
linear relationship between ammonia and potassium in groundwater chemistry observed at RSK
well clusters. Of these well clusters, RSK 8-12 and RSK 16-20 show the highest concentrations
of ammonia and potassium. In addition, potassium concentrations at these well clusters exceed
those observed at existing landfill wells SHP-99-29X and N5-P1. Although there is a more
limited dataset, methane concentrations at well clusters RSK 13-15 and RSK 8-12 are generally
consistent with the range of methane concentrations observed at existing landfill wells SHP-99-
29X, N5-P2 and N5-P1. Based on these trends, elevated concentrations of ammonia and
methane could potentially indicate an influence of solid waste degradation on groundwater
chemistry, given that existing well N5-P2 is completed within buried landfill material and the
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proximity of the well screen at SHP-99-29X to buried solid waste. These observations suggest
the need for a more complete characterization of the vertical and aerial extent of groundwater
constituents within the saturated aquifer underlying the central portion of the landfill, particularly
the area that is upgradient to Red Cove relative to groundwater flow potential (CH2MH111, 2006).
The potential importance of this data gap is illustrated by examination of the vertical trends in
ammonia and methane observed at well clusters N5-P1,P2, RSK 13-15, and RSK 8-12 (Figure
43). The methane concentration observed at well screen RSK 10 is consistent with that observed
at shallow well screen N5-P2 within the central portion of the landfill. As illustrated in Figure
43, there is nearly 60 feet of saturated overburden aquifer for which monitoring data are not
available within the central portion of the landfill. This data gap for such a large portion of the
aquifer in contact with the landfill significantly limits the reliability of estimating the sources or
extent of arsenic flux through the aquifer. This presents a significant limitation to understanding
arsenic transport to Red Cove, as well as remedial design options that might be available to
reduce/eliminate this contaminant discharge.
3.3 Groundwater Chemistry Trends: RSK Wells and Red Cove
Comparison of major element chemistry for shallow groundwater underneath Red Cove and
groundwater from RSK wells is shown in Figure 44. A linear trend was fit to the data from RSK
wells in order to simplify the presentation. The range of concentrations for chloride, sodium and
potassium are highlighted for well clusters RSK 1-7, RSK 16-20 and RSK 8-12. This
comparison reveals that the water chemistry in the majority of RCTW wells, with the exception
of two locations sampled in 2006, is consistent with the chemical conditions of RSK wells where
the highest concentrations of arsenic were observed. As a point of reference, concentrations of
chloride, sodium and potassium are also shown for shallow surface water samples collected from
Red Cove during 2006-2007. In general, shallow surface water is chemically distinct from
shallow groundwater within the cove as demonstrated by the significant disparity in potassium
concentrations. The range in potassium concentrations for RCTW wells was 6.1-13.4 mg/L
(except RCTW6 at 2.6 and 5.8 mg/L in August 2006 and August 2007, respectively), whereas
the observed range for shallow surface water in Red Cove was 1.2-2.0 mg/L during 2006-2007.
It should be noted that RCTW6 is located proximate to the region of Red Cove where sediment
temperature button data indicated significant influence by surface water (e.g., Figure 33). This
information indicates that potassium may be used as a marker to estimate the influence of
shallow surface water on chemical characteristics in shallow groundwater and deep surface water
proximate to sediments within Red Cove.
Snapshots of shallow groundwater chemistry underlying Red Cove are shown in Figures 45 and
46. These data were collected from shallow RCTW wells that were sampled during August 2006
and August 2007. These discrete data were used to generate isoconcentration contours for the
portion of the cove in which RCTW wells were installed. In general, these observations indicate
that the highest arsenic concentrations in shallow groundwater occur within the central portion of
the cove, although this observation is limited somewhat by the number and distribution of
monitoring points. Analysis of the chemical speciation of arsenic in groundwater indicates that
arsenite [As(III)] is the predominant form in both RSK and RCTW wells (Figure 47).
Measurement for the chemical species arsenate [As(V)], MMA and DMA indicated these species
were present at or below the analytical detection limit (generally <15 |ig/L). Patterns in the
concentration of bicarbonate, dissolved iron and sulfate also suggest that microbial sulfate-
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reduction may be occurring within the southeast area of the cove. Generally, microbial sulfate
reduction would result in elevated alkalinity and depressed sulfate concentrations. If reduced
iron were present, it would likely be scavenged from groundwater during precipitation of iron
sulfide. These chemistry patterns were generally consistent for both monitoring dates.
3.4 Groundwater Chemistry Summary
Comparison of water chemistry data from multiple sources and sampling dates indicates general
consistency among existing wells adjacent to Red Cove and EPA/ORD well installations
monitored as part of this study. Based on hydrologic data reported in the previous section and
the depth distribution of arsenic within the overburden adjacent to Red Cove, elevated
concentrations of arsenic can be attributed, in part, to groundwater from the aquifer underlying
Shepley's Hill Landfill. While chemical mixing calculations for groundwater sampled under the
central portion of the landfill are reflective of chemical characteristics observed at well cluster
RSK 8-12, the lack of available chemistry data or monitoring points for reasonable upgradient
groundwater flow paths prevents identification of the source of elevated arsenic discharging to
Red Cove. For RSK wells, elevated arsenic concentrations generally correlate with reducing
conditions that maintain elevated concentrations of reduced iron in groundwater. Comparison of
water chemistry in shallow groundwater underlying Red Cove (RCTW wells) and the chemistry
of shallow surface water indicates that groundwater discharge constitutes a significant source of
arsenic in Red Cove. Analysis of patterns in potassium concentrations throughout groundwater
and surface water indicate that this constituent, in combination with shallow sediment
temperature data, provides a reasonable tracer for mapping locations of arsenic plume discharge
into Red Cove. The pattern in potassium concentrations in RCTW wells relative to shallow
surface water is consistent with the interpreted distribution of groundwater discharge within Red
Cove as reflected by in-situ measurements of groundwater discharge and shallow sediment
temperature.
3.5 References
CH2MH111, 2006 Annual Report, Shepley's Hill Landfill Long Term Monitoring & Maintenance,
Devens, Massachusetts". Prepared for the Department of the Army, BRAC Environmental,
Devens, Massachusetts.
Gannett Fleming, Inc., 2006. "Final Expanded Site Investigation, Grove Pond and Plow Shop
Pond, Ayer, Massachusetts", prepared for the U. S. Environmental Protection Agency, Region 1,
Boston, Massachusetts, (http://www.epa.gov/ne/superfund/sites/devens/246620.pdf)
Final Report 30 September 2008 EPA/ORD
-------
922740
922730 -
922720 -
922710 -
922700 -
922690 -
-ฃ 922680 -
O) 922670 -
O 922660 -
922650 -
922640 -
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922620 -
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75
SHL-20
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SHL-4
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A Surface Water
Army
Region 1 DPT 2004
Cove Perimeter
SHL-19
192160
I
192180
I
192200
192220
I
192240
r
192260
Easting (meters)
Figure 34. Aerial locations of RSK and RCTW wells installed by EPA/ORD within the
groundwater aquifer adjacent to and underlying Red Cove. The locations of nearby wells
installed by the Army are shown for reference. Estimated locations are shown for EPA Region 1
direct-push sampling locations conducted in 2004. Sections labeled A-A' and B-B' are
referenced in Figure 35.
Final Report
30 September 2008
EPA/ORD
-------
76
Northing (meters)
922620 922640
i 1 , 1
220 -
216 -
_
212 -
^v
0) 208 -
< 204 -
ti
^ 200 -
0
'ro 196 -
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r
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(D
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Figure 35. Cross-sectional view of the distribution of screened depths of the EPA/ORD
groundwater chemistry monitoring network (RSK and RCTW wells) and nearby wells installed
by the Army. Two views are shown consistent with sections A-A' and B-B' depicted in Figure
29. Well mid-depth and screen length are depicted as a data point with error bars. Surface water
in Red Cove is represented by the blue shaded region.
Final Report
30 September 2008
EPA/ORD
-------
77
RSK1-7
Army 2006-2007
O RSK 16-20
D RC1.EPA/R1 2004
RSK 8-12
RC2, EPA/R1 2004
Army 2006-2007
RSK 13-15
Army 2006-2007
O RSK 37-42
916
919
CO 908
-------
78
C/)
220-
215-
210-
205-
o 200-1
"co
u 195-
190-
185
RSK 1-7
RSK 16-20
RSK 8-12
RSK 13-15
RSK 37-42
^ I ' I ' I ' \
0 100 200 300 400
HCO, (mg/L)
\
4
T
8
12 0
NH-N (mg/L)
5 10 15
SO. (mg/L)
20
Figure 37. Comparison of bicarbonate (HCOs), ammonia-nitrogen (NH3-N) and sulfate (864) concentrations as a function of depth
among all RSK well clusters. The mean and standard deviation is shown for all sampling dates (see Appendices for individual data).
(Values for HCOs can be calculated from alkalinity by the following formula: HCOs (mg/L) = 1.219 * Alkalinity (mg CaCOs/L).)
Final Report
30 September 2008
EPA/ORD
-------
79
-
?n
-
^
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0 -
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-- RSK13-15
O RSK 37-42
n SHL(R1,Oct2007)
O^HP-99-29X(RD ฐ SHL (Army, 2006-2007)
u 1
0 10 20 30 40
Na (mg/L)
K (mg/L)
Figure 38. Patterns in the concentrations of dissolved (0.45 |im filtered) sodium (Na), potassium (K), and chloride (Cl) are shown for
RSK wells. Also shown are similar dissolved concentration data collected by Region 1 in October 2007 for a select set of Army wells,
as well as the average and standard deviation of all total concentration measurements conducted by the Army in 2006-2007. See
Appendix A for location of all Army wells within and adjacent to Shepley's Hill Landfill.
Final Report
30 September 2008
EPA/ORD
-------
80
10000 .
1000 .
100 .
10 .
SHP
SHP-S
SHP-01
N7-P1(
(
I
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1000
100
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0 100 200 300 400 500 600 700 800
HC03 (mg/L)
0 20 40 60 80 100 120 140
Ca (mg/L)
h
*
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>.
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n SHL(R1, Oct2007)
n SHL (Army, 2006-2007)
v RC1 (R1 , 2004)
A RC2 (R1 , 2004)
D 2
0 4
0 60 80
Fe (mg/L)
Figure 39. Patterns in the concentrations of bicarbonate (HCOs), dissolved (0.45 |im filtered) calcium (Ca), dissolved iron (Fe), and
dissolved arsenic (As; 0.45 |im filtered) are shown for RSK wells. Also shown are similar dissolved concentration data collected by
Region 1 in October 2007 for a select set of Army wells, as well as the average and standard deviation of all total concentration
measurements conducted by the Army in 2006-2007. Data for As, Ca, and Fe are shown for direct-push samples collected by Region
1 in 2004 adjacent to Red Cove.
Final Report
30 September 2008
EPA/ORD
-------
W
240-
220-
200-
180-
160-
LU
120-
100-
80-
ISHL-15
ro
9
Q_
JBN7-P2
^olWh^j
- J^HW +
k*b ^^
SHL North (Oct07)
SHL North (Jan06 - Oct07)
SHL N5 (Jan06 - Oct07)
SHL-15& N7(Oct07)
RSK 37-41 (2006-2007)
RSK 13-15 (2006-2007)
RSK 1-7 (2006-2007)
RSK 16-20 (2006-2007)
RSK 8-12 (2006-2007)
81
Bedrock Elevation
(ft AMSL)
SHL-5
SHL-9A
i J RSK 13-15
RSK 16-20RSK 37-42
ฃ ^~ RSK 8-12
CL ^^RSK1-7
t SHM-96-5C
;" f
^^
SHM-93-22B
SHM-96-5B
SHL-22
SHM-93-22C
0 2 4 6 8 10 12 14 16 18 20 22
K (mg/L) *
North (OctOT)
North (Dec06)
SHL North (Jun06)
SHL North (Apr06)
SHL North (Jan06)
-240
-220
-200
-180
-160
-140
-120
-100
-80
*& ฐ
Easting (m)
1000 2000 3000 4000 5000
AS
Figure 40. Vertical trends in groundwater chemistry for RSK wells and existing wells within the southern, central portions and just
north of Shepley's Hill Landfill (SHL). Left panel - potassium concentration as a function of screen elevation; middle panel -
elevation of bedrock for displayed wells (blue hashed area for wells in northern portion of SHL); right panel - arsenic concentration as
a function of screen elevation. 'SHL North' refers to wells SHL-5, SHL-9, SHM-96-5C, SHM-93-22B, SHM-96-5B, SHL-22, and
SHM-93-22C.
Final Report
30 September 2008
EPA/ORD
-------
82
w
4000 -
3000 -
ซ-
.--
1000 -
~
800 -
600 -
-
400 -
_
200 -
QN5-P1
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- 1000
- 800
- 600
-
- 400
_
- 200
80 0 5 10 15 20 25
>
(A
(Q
Fe (mg/L)
Sitewide Soil (all samples)
North Post Soil (Soil-1, -2, -3, -4)
Sitewide Soil (68th percentile)
RSK 37 (aquifer fines)
^^ RSK 2 (aquifer fines)
RSK1-7(GW)
O RSK16-20(GW)
RSK 8-12 (GW)
RSK 13-15 (GW)
O RSK 37-42 (GW)
D N5-P1, P2 (GW, Army 2006-2007)
D N7-P1 ,P2 (GW, R1 Oct 2007)
K (mg/L)
Figure 41. Concentration of arsenic versus iron (left panel) and potassium (right panel) for RSK
wells and existing piezometer clusters in the southern and central portions of Shepley's Hill
Landfill (CH2MHill, 2006; Ginny Lombardo, 12/21/2007 e-mail correspondence). Linear trends
shown for site soils (1993 RI Addendum) and aquifer fines recovered during development of
well screens at RSK 2 and RSK 37 (Table 8) are calculated based on the measured ratio of
extractable iron and arsenic in solid materials assuming congruent dissolution of these elements.
The blue-hatched region is based on all site soils, including those considered to be compositional
outliers. The y-axis has a break at 2600 |ig/L As to facilitate display of all data.
Final Report
30 September 2008
EPA/ORD
-------
83
Aerial View
0 4 6 8 10 12 14 16 18 20 2
10000
8000
6000 g
-4000 i-
2000
Cross-Section View
RSK 8-12
RSK 13-15
Ugani
--ซ""' 39% (K)
Crn jfJ bujj Ji
24% (As
id ~
*.
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l ccfidfems between 6ป>pK.rMflM may ซry
Genarilly frit to warse with traces ofซ and
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I Zoปปซo( patents^ rughBrpvniHWIty.
Very dense; wall gradfd injm tin to gravel
^ mttridiue IDTIM relative to san
Figure 42. Location of SHP-99-29X and N5- P2 wells within the central portion of Shepley's
Hill Landfill (SHL) relative to RSK well clusters adjacent to Red Cove ('aerial view'). Upper,
right-hand panel displays groundwater concentrations of ammonia (NHs-N) and methane (CFL;)
versus potassium. The gray trend line represents a linear fit to all ammonia-potassium data for
RSK wells (EPA/ORD 2006-2007). Methane data were collected by EPA/ORD during
September 2007 from well clusters RSK 13-15, RSK 8-12, SHP-99-29X and N5-P1,P2. Bottom
panel displays relative elevations of sampled well screens; percentages (red text) show estimates
of mixtures from groundwater at N5-P2 and SHP-99-29X needed to approximately reproduce
average potassium/arsenic concentrations observed at RSK 8-12 for September 2007. Source of
aerial and cross-section landfill views: Harding ESE, Inc. 2003. Shepley's Hill Landfill
Supplemental Groundwater Investigation, Devens Reserve Forces Training Area. Devens,
Massachusetts.
Final Report
30 September 2008
EPA/ORD
-------
84
220
190 -
180 -
=ง 170 -i
>
U 160-
150 -
140 -
methane
, methane
* N5-P1.P2, methane
* SHP-99-29X, methane
RSK8-12, bedrock
RSK13-15, bedrock
^ N5, bedrock
SHP-99-29X, bedrock
Distribution of groundwater
constituents at N5-P1,P2?
I
2
4 6 8 10
NH-N (mg/L)
o
RSK8-12
RSK13-15
12
Figure 43. Concentrations of ammonia (NHs-N) and methane (CH4) measured in groundwater
for a subset of RSK wells and at SHL wells SHP-99-29X, N5-P2, and N5-P1 during September
2007. The elevation of bedrock is shown for the sampled locations.
Final Report
30 September 2008
EPA/ORD
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85
30 -
A SW03 8/07
&SW02B 8/07, SW04 9/07, SW05 9/07
RSK Linear Trend
O RCTW2006
RCTW2007
A Shallow SW 2006-2007
X SW02A 4/07
A MC 5/06
A i r.
O)
E
O 20 -
10 -
0 -
10
Na (mg/L)
K (mg/L)
Figure 44. Measured concentrations of chloride (Cl), sodium (Na) and potassium (K) for groundwater samples collected from RCTW
wells during 2006-2007. For comparison, linear trends fit to RSK groundwater data shown in Figure 32 are shown, along with the
range of concentrations observed for well clusters RSK 1-7, RSK 16-20 and RSK 8-12. Data for Red Cove surface water samples
(shallowest depth) collected during 2006 and 2007 are shown for reference; data label shows sampling month and year.
Final Report
30 September 2008
EPA/ORD
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86
922720
922710
922700
32 922690
O>
^ 922680
O)
g
Jz 922670 -
922660
922650
922640
922720
922710
^ 922700
B 922690
O>
^ 922680
O)
c
o
922670 -
922660
922650
922640
RSK 1-7
(642-995)
RSK 37-42
SHL-4 JU RSK 13.15 ^ fagflj
JO
I
I
0
125
250
375
500
625
750
875
1000
10
18
27
36
44
53
61
70
922720
922710
922700
922690
922680
922670
922660
922650
922640
922720
922710
922700
922690
922680
922670
922660
922650
922640
(284-344)
Q>
Q>
HCO, (mg/L)
I ' I ' I ' I ' I ' I ' I ' I
/SOA (mg/L)
(4.1-15.5)
JO
o
50
1 100
150
200
250
300
350
MOO
9
MO
Easting (meters)
Easting (meters)
Figure 45. Spatial pattern in shallow groundwater chemistry underneath Red Cove sediments based on contouring of chemical data
collected for wells RCTW 1-10 during August 2006. Individual well screen concentrations are shown in black text next to the RCTW
well location. The ranges of As, bicarbonate (HCOs), Fe, and sulfate (864) concentrations for RSK 1-7 are shown in parentheses for
comparison.
Final Report
30 September 2008
EPA/ORD
-------
87
922720 -
922710-
922700 -
ฃ 922690 -
O>
^ 922680-
O)
g
Jz 922670 -
O
~Z. 922660 -
922650 -
922640
922720 -
922710-
^ 922700-
ฃ 922690 -
O>
^ 922680-
O)
g
!c 922670 -
O
~Z. 922660 -
922650 -
922640
RSK 16-20
Q) RSK 8-12
SHL-4J0 RSK 13-15
RSK 37-42
(3-596)
As (jug/L)
Q>
(18-39)
Fe (mg/L)
(0.02-46)
I
o
125
250
375
500
625
750
875
1000
.
10
18
27
36
44
53
61
70
922720
922710-
922700
922690
922680
922670
922660
922650
922640
922720
922710-
922700
922690
922680
922670
922660
922650
922640
(230-268)
HCO. (mg/L)
(10.5-16.2)
S04 (mg/L)
Q>
(4.2-11.9)
o
50
100
150
200
250
300
350
400
Easting (meters)
Easting (meters)
Figure 46. Spatial pattern in shallow groundwater chemistry underneath Red Cove sediments based on contouring of chemical data
collected for wells RCTW 1-10 during August 2007. Individual well screen concentrations are shown in black text next to the RCTW
well location. The ranges of As, bicarbonate (HCOs), Fe, and sulfate (804) concentrations for RSK 1-7 and RSK 37-42 are shown in
parentheses for comparison.
Final Report
30 September 2008
EPA/ORD
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88
1200 -
1000
800
600
400
200
0 -
200
400 600 800
Dissolved As (|ig/L)
1000 1200
Figure 47. Comparison of the measured concentrations of dissolved (0.45 |im filtered) arsenic
and the arsenite [As(III)] chemical species in filtered groundwater sampled from RSK and
RCTW wells. The line represents a direct linear correlation between the two measurements.
Final Report
30 September 2008
EPA/ORD
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89
Table 8. Concentration data for aquifer solids collected during purging of well screens at RSK2
and RSK37 along with groundwater data collected on August 8, 2006 (RSK2) and August 22,
2007 (RSK37).
Element
Al
Ca
Fe
K
Mg
Mn
Si
As
Cr
Cu
Hg
Ni
Pb
Zn
RSK2
Aquifer Solids
(mg/kg)
8260
3500
5410
1690
1060
185
10600
(mg/kg)
10
6.3
4.2
0.04
7.4
3.7
9.5
Groundwater
(mg/L)
ND
64.9
28.5
8.3
10.1
3.6
17.7
(M8/L)
814
1
0.5
0.06
12
ND
15
RSK37
Aquifer Solids
(mg/kg)
34200
2320
25400
5040
4740
264
29400
(mg/kg)
124
35
32.2
0.06
37.6
22.7
59.6
Groundwater
(mg/L)
ND
5.1
0.02
1.2
1.2
0.01
3.4
(M8/L)
3
ND
0.2
0.02
0.6
ND
40
Final Report
30 September 2008
EPA/ORD
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90
4 Surface Water and Sediment Chemistry Studies
The objectives of the surface water and sediment chemistry studies performed at the Fort Devens
sediments research site included determination of the spatial patterns in metals concentrations in
sediments within Red Cove, the chemical speciation of arsenic in sediments, and the spatial
patterns in the chemical characteristics of surface water in several locations within the cove. The
purpose of these measurements was to identify contaminants in addition to arsenic that might
influence risk due to exposure to sediments and/or surface water and to assess the relative
contribution of groundwater discharge and sediments to contaminant concentrations in overlying
surface water. In addition, knowledge of the characteristics of in-place contaminated sediments
was used as a point of reference for assessing the chemical stability of sediment-associated
arsenic. Investigations included the collection of sediment cores in three transects across Red
Cove and collection of depth-discrete chemistry data for surface water, including limited
collection of suspended solids at a location of known contaminated groundwater discharge. Data
and results from these studies are discussed below.
4.1 Monitoring Network
Sampling of sediment, co-located pore water/shallow groundwater, and surface water was
conducted from a pontoon boat during September 2005 (sediment coring, push-point sampling),
May 2006 (surface water), April 2007 (sediment coring, surface water), August 2007 (surface
water), and September 2007 (surface water). Push-point samples were collected via peristaltic
pump according to the low-flow sampling protocol employed for groundwater wells. The
locations of push-point sampling points are shown in Figure 48. A total of 12 intact sediment
cores were collected from Red Cove along three transects (Figure 49). The length of recovered
sediment core ranged from 16 to 39 inches. Sediment core sleeves were immediately capped
upon retrieval and frozen on-site prior to shipment to an EPA laboratory. Sediments collected
from Transect 2 ("0201-0204" series) and Transect 3 ("0301-0303" series) were typified by a
black organic gelatinous layer overlaying a dense sand layer. All cores collected exhibited this
visual characteristic except for a single core (SCT0303) that exhibited an additional layer of
black material within the sandy layer. Sediment cores collected from Transect 1 ("0101-0103"
series) were comprised of a gelatinous organic layer overlaying a very fine sand- and silty-layer.
The cores were partitioned into 2-4 inch segments and allowed to dry in the absence of oxygen in
order to preserve the chemical speciation of redox-sensitive constituents within the sediment.
Each segment was analyzed for elemental composition with microwave-assisted acid extraction,
and the arsenic solid-phase speciation was determined for a majority of the core sections using
X-ray Absorption Near-Edge Spectroscopy (XANES). Depth-discrete surface water samples
were collected from several locations within Red Cove to ascertain the spatial distribution of
arsenic within the water column. Samples were retrieved via peristaltic pump following
equilibration of in-situ water quality parameters measured using a YSI 556 water quality sonde
deployed at the sampling depth (see Appendices). Monitoring point SW02B was located
proximate to the existing seepage meter deployment SM1B and EPA/ORD cove piezometer PZ5
(see Figures 24, 29 and 49). The location of all surface water monitoring points is shown in
Figure 49. The relative locations of sediment cores and temperature button transects (Section 2)
are shown in Figure 50 in order to facilitate discussion of apparent patterns in groundwater
discharge and sediment arsenic concentrations. Discussion of results from analysis of sediment
chemistry, pore water chemistry and surface water chemistry follows.
Final Report 30 September 2008 EPA/ORD
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91
4.2 Sediment Chemistry
The transition zone from groundwater to surface water in Red Cove is characterized by a sharp
transition from reducing to oxidizing conditions. This is visually evidenced by the pervasive
precipitation of reddish-orange iron oxides along the cove shoreline and within the water column
in locations with minimal growth of aquatic plants. The formation of iron oxides in these
locations is due to discharge of groundwater with high concentrations of ferrous iron [Fe(II)]
and/or release of Fe(II) from sediments, which subsequently comes in contact with dissolved
oxygen. Based on measurements in RSK wells, dissolved oxygen concentrations are too low in
groundwater to support significant oxidation and precipitation of Fe(II) within the aquifer.
Elevated dissolved iron concentrations similar to those observed in RSK and RCTW wells were
also observed in push-point samples collected from a depth of approximately two feet below the
sediment surface (Figure 51). Thus, the majority of Fe(II) oxidation and precipitation occurs
following groundwater discharge into overlying surface water, which is supported by comparison
to the lower acid-extractable iron concentrations in aquifer solids retrieved during development
of well screens from the northern and southern boundaries of the cove (Table 8). Comparison of
the acid-extractable concentration of iron in these aquifer solids (0.5-2.5 wt% Fe) to those
observed in shallow sediments (<4 inches below sediment-water interface; 1.5-37.4 wt% Fe)
throughout Red Cove (Figure 52, left panel) confirm that the majority of ferrous iron oxidation
and precipitation within the cove occurs in proximity to the sediment surface. As discussed later,
this is also consistent with the depth distribution of acid-extractable iron in sediment cores.
Comparison of the solid phase concentration of arsenic in these aquifer solids (10-124 mg/kg As)
to shallow sediments (137-8600 mg/kg As) or suspended solids (6533 mg/kg As) collected
within Red Cove indicates that precipitation of iron with coprecipitation/sorption of arsenic is the
most likely source of elevated concentrations observed in Red Cove solids. There is a consistent
relationship between acid-extractable iron and arsenic in shallow sediments throughout Red
Cove and suspended solids collected at depth from surface water sampling location SW02B
(Figure 52, right panel). As documented for similar settings (Ford et al., 2005), the most likely
source of the reddish-orange precipitates is the mineral ferrihydrite. Based on the theoretical
chemical formula of the mineral ferrihydrite, the iron content of the pure mineral is
approximately 58.1 wt% Fe (FesHOg^F^O; Berquo et al., 2007). As a point of reference, this
compares to the following iron contents of common iron-bearing minerals in reduced
environments: 1) mackinawite (FeS), 58.1 wt% Fe; 2) pyrite (FeS2), 46.5 wt% Fe; and siderite
(FeCOs), 48.2 wt% Fe. These are all commonly occurring iron-bearing minerals in low-
temperature environments that are extractable under the analytical conditions employed for
determination of solid phase iron in Red Cove solids. Measured sediment iron concentrations on
the order of 20 wt% Fe or more are indicative of a significant contribution from these types of
minerals. The total acid-extractable iron content will generally be diluted below that for the pure
mineral due to organic carbon derived from aquatic plant die-off and sands/silts from soil
erosion.
In an effort to survey sediment chemistry and mineralogy below the sediment-water interface
and to determine its impact on the potential attenuation, mobilization, and bioavailability of
arsenic, the solid-state speciation of arsenic in the sediment was determined. The elements
released by microwave-assisted acid digestion indicate Fe, Mn, Al, Si, S, As and Cr as the most
Final Report 30 September 2008 EPA/ORD
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abundant elements of those measured (Appendix L). Acid-extractable arsenic concentrations
ranged between 137-8600 mg/kg in the top two inches of the sediment, but tended to decrease
rapidly with depth (Figure 53). The rapid decline in the concentration of arsenic in the sediment
profile indicates that arsenic derived from groundwater discharge accumulates or is sequestered
at or near the sediment-water interface. Although other elements in the cove indicate a partial
correlation, Fe is consistently associated with arsenic horizontally and vertically throughout the
sediment thickness (Figure 52; see Appendix J for all depths).
In addition to the bulk elemental analysis, the solid-phase speciation of arsenic was determined
in each core segment with bulk XANES. Spectra for the set of arsenic reference phases used to
represent possible arsenic species anticipated for conditions at Red Cove are shown in Figure 54.
Bulk XANES analysis of the top two inches of sediment identify a mix of 2 to 4 primary arsenic
bearing phases over all 12 sediment cores (Tables 9-11 and Figures 55-57). The most common
phase identified was As(III) or As(V) adsorbed/coprecipitated with iron oxide as represented by
As(III) or As(V) coprecipitated with ferrihydrite. Arsenic was also associated with iron sulfides
as a reduced adsorbed species, either arsenite coprecipitated with pyrite or mackinawite. The
profile distribution and concentration of each of the arsenic solid phases identified by XANES
spectroscopy in the Red Cove sediments is presented in Figures 55-57. Speciation of arsenic in
the top two inches of sediment appears to show some general spatial trends (Figure 58; left
panel). First, arsenic speciation in shallow sediments is dominated by partitioning of As(III) or
As(V) to an iron oxide such as ferrihydrite. Secondly, arsenic is more common in its reduced
form, As(III), in the middle to western portion of the cove, whereas a greater fraction of As(V)
appears in the eastern portion of the cove. Finally, the presence of arsenic associated with iron
sulfides in shallow sediments primarily occurs in the middle of the cove where evidence of
groundwater discharge with elevated arsenic concentrations is strongest. This is generally
consistent with the distribution of acid-extractable sulfur in shallow Red Cove sediments (Figure
58; right panel). It has previously been documented that iron oxides have a greater capacity for
arsenic uptake than iron sulfides (Wilkin, 2006). This behavior is also apparent for Red Cove
where shallow sediments with the highest iron and arsenic contents generally have lower sulfur
contents with a weak correlation between solid phase arsenic and sulfur (R2 = 0.14).
4.3 Surface Water Chemistry
Trends in surface water chemistry as a function of depth in Red Cove are shown in Figures 59-
62. Characterization data for suspended solids collected from deep surface water at sampling
location SW02B (April 2007) are shown in Figure 60. X-ray diffraction data and chemical
composition confirm that the solids consist of the hydrous iron oxide mineral, ferrihydrite. The
lower iron content for this natural sample (i.e., 37.8 wt% versus 58.1 wt% for the ideal mineral
structure) is due to the presence of other coprecipitated elements such as calcium, sodium and
potassium. This poorly crystalline mineral phase commonly precipitates out in surface water
bodies where dissolved, ferrous iron comes in contact with dissolved oxygen (Ford et al., 2006).
This mineral precipitate has a reddish-orange color and is the source of the orange hue imparted
to the surface water at this sampling location (photograph in Figure 60). This same mineral
precipitate is the source of the orange staining along the banks surrounding Red Cove.
Ferrihydrite has the capacity to sorb weight percent levels of arsenic [as As(III) or As(V)],
particularly under situations in which arsenic is present in solution during mineral precipitation
(Ford, 2002). The potential for iron sulfide formation to occur within the water column was
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assessed by comparing measured redox and pH characteristics of water samples to the relative
stability of ferrihydrite-pyrite and ferrihydrite-mackinawite solid pairs (Figure 63). These
comparisons indicate that the shallow sediment layer is the only location where iron sulfides may
persist based on thermochemical considerations. In addition, assessment of the potential stability
of poorly crystalline orpiment, relative to iron sulfides, indicates that the precipitation of a pure
arsenic sulfide phase is not supported from thermochemical considerations (Figure 64). Thus,
sorption of aqueous arsenic onto iron oxides appears to be the most likely control on solid phase
arsenic speciation within the water column. Aqueous arsenic speciation below the sediment
surface (push-point samples) and surface water in Red Cove is dominated by arsenite [As(III)]
(Figure 65; left panel). The depth trend in distribution between As(III) and As(V) within the
water column generally indicates that the dominance of As(III) continues throughout the water
column (Figure 65; right panel).
The arsenic sorption characteristics of ferrihydrite precipitating within the Red Cove water
column was characterized through examination of measured dissolved and particulate
concentrations of arsenic and iron in filtered (0.45 |im) and unfiltered surface water samples.
Particulate concentrations were determined by difference for unfiltered (acid digested) and
filtered samples. The results of this analysis are shown in Figure 66 (left panel), where an in-situ
arsenic sorption capacity of approximately 20,000 mg As/kg ferrihydrite was estimated based on
the best fit of the Langmuir isotherm equation to the data. The patterns in dissolved ferrous iron
[Fe(II)] and particulate iron as a function of dissolved total iron are shown in the right panel of
Figure 66. These data indicate that elevated dissolved iron within the water column is attributed
primarily to Fe(II) and these elevated Fe(II) concentrations drive the formation of particulate iron
(as ferrihydrite). This reaction is sustained by the generally shallow depth within the cove and
the availability of dissolved oxygen. Published data from a similar setting indicates that Fe(II)
oxidation and precipitation of ferrihydrite is a rapid reaction (Ford et al., 2006), which serves to
sequester arsenic derived from groundwater discharge and maintain relatively low concentrations
of arsenic in shallow surface water (see Figures 59-62 and Appendices).
Trends in the general water chemistry of deep surface water, as reflected in concentrations of
chloride, potassium and sodium, are shown in Figure 67. The concentration of potassium can be
used as an indicator of the relative distribution of groundwater (represented by RCTW
chemistry) and shallow surface water (shown as a hashed, gray area in each panel). Based on
analysis of these data, surface water sampling locations 1C, SW04, and SW05 appear to represent
areas within the cove in which surface water chemistry is less strongly influenced by
groundwater discharge. In contrast, surface water sampling locations MC and SW02B appear to
be dominated by groundwater discharge, with locations SW02A and SW03 displaying
compositions indicative of intermediate influence of the two water sources. It should be noted
that the values plotted for "deep" surface water have been interpolated from measured depths for
each dataset to represent a consistent height above the sediment surface. For depths closer to the
sediment surface at locations SW02A, SW02B and SW03, the water chemistry trends closer to
that of groundwater sampled from neighboring RCTW wells. This observation is illustrated in
Figure 68 with comparison of contoured potassium concentrations in RCTW wells to
concentrations in the deepest surface water sample collected at each location. Smaller
differences in potassium concentrations in shallow groundwater and deep surface water indicate
a significant influence from groundwater discharge. It should be noted that this comparison does
Final Report 30 September 2008 EPA/ORD
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not take into account the potential influence of vertical mixing within the water column as a
result of seasonal turnover or other physical factors such as wind. However, comparison of
results from measurement of shallow sediment temperatures within the cove to contoured
potassium concentrations in shallow groundwater indicate reasonable correspondence between
interpreted locations of groundwater discharge to surface water (Figure 69).
The range of interpolated arsenic concentrations for equivalent depths in deep surface water as a
function of interpolated potassium concentrations is shown in Figure 70. In addition, measured
dissolved arsenic and potassium concentrations are shown for the shallowest surface water
sample collected at each location. Again, there is a clear distinction between the chemical
composition of shallow and many of the deep surface water data, including locations MC and
SW02B. Potential regulatory benchmarks for surface water are also shown on this plot (USEPA,
2006a; USEPA, 2006b). For arsenic, current statutes list both acute and chronic ambient water
quality criteria (AWQC) for arsenic in fresh waters as 340 |ig/L and 150 |ig/L, respectively.
Comparison of the distribution of arsenic concentrations in shallow groundwater (RCTW wells),
sediments and deep surface water is provided in Figure 71. Historical sediment data for Red
Cove are also shown as a point of reference (Figure 71; left panel). There is general
correspondence between contaminated groundwater discharge and elevated arsenic
concentrations in deep surface water. The highest concentrations of arsenic in deep surface
water appear to occur where sediment data suggests iron sulfides are being produced. The
spatial relationship between calculated arsenic flux at RSK wells and Red Cove sediment
concentrations is shown in Figure 71. Isoconcentration contours for sediment arsenic were
derived from EPA/ORD shallow sediment data and historical data available for Red Cove
(Gannett Fleming, 2006). Comparison of the distribution of potassium in shallow groundwater
underlying Red Cove and the pattern in arsenic sediment concentrations indicates a general
relationship to contaminated groundwater discharge (Figure 72). It should be noted that
sediments most likely provide a record of accumulated arsenic flux from groundwater, while the
potassium data reflect an instantaneous measure in time of contaminated groundwater discharge.
4.4 Sediment and Surface Water Chemistry Summary
Sediment and surface water chemistry data all indicate that arsenic is present in a reduced form
within Red Cove. Patterns in the concentrations of major elements in groundwater, surface water
and sediments point to discharge of contaminated groundwater as the primary source of elevated
arsenic in Red Cove sediments and deep surface water. Patterns in sediment temperature and
potassium concentration distribution in shallow groundwater underlying Red Cove generally
align with the estimated distribution of contaminated groundwater discharge into the cove. The
elevated concentration of potassium in deep surface water appears to be an indicator for plume
discharge. There is general correspondence between the locations of highest sediment arsenic
concentrations and suspected locations of contaminated groundwater discharge. Precipitation of
ferrous iron derived, in part, from groundwater discharge is prevalent throughout the cove
following exposure to dissolved oxygen within surface water. Iron oxide precipitation results in
sequestration of arsenic within the water column and appears to be the primary cause for lower
arsenic concentrations observed in shallow surface water. However, iron oxide precipitates
formed within the water column are unstable in reducing sediments and may likely serve as a
continued source of arsenic flux to surface water after settling out from the water column. While
Final Report 30 September 2008 EPA/ORD
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the highest concentration of arsenic observed in deep surface water was co-located with a known
area of plume discharge, elevated concentrations of arsenic in locations with less dominant
influence of groundwater discharge document the potential instability of arsenic in contaminated
sediments.
4.5 References
Berquo, T. S., Banerjee, S. K., Ford, R. G., Penn, R. L. and Pichler, T., 2007. High crystallinity
Si-ferrihydrite: An insight into its Neel temperature and size dependence of magnetic properties.
Journal of Geophysical Research, 112, B02102, doi:10.1029/2006JB004583.
Ford, R. G., 2002. Rates of hydrous ferric oxide crystallization and the influence on
coprecipitated arsenate. Environmental Science and Technology, 36(ll):2459-2463.
Ford, R. G, Wilkin, R. T., Scheckel, K. G, Paul, C. I, Beck, F., Clark, P., Lee, T. 2005. Field
Study of the Fate of Arsenic, Lead, and Zinc at the Ground-Water/Surface-Water Interface, EPA
Report, U.S. Environmental Protection Agency, Cincinnati, OH, EPA/600/R-05/161.
Ford, R. G., Wilkin, R. T., Hernandez, G. 2006. Arsenic cycling within the water column of a
small lake receiving contaminated ground-water discharge. Chemical Geology, 228(1-3): 137-
155.
Gannett Fleming, Inc., 2006. "Final Expanded Site Investigation, Grove Pond and Plow Shop
Pond, Ayer, Massachusetts", prepared for the U. S. Environmental Protection Agency, Region 1,
Boston, Massachusetts, (http://www.epa.gov/ne/superfund/sites/devens/246620.pdf)
USEPA. 2006 Edition of the Drinking Water Standards and Health Advisories. EPA 822-R-06-
013, Office of Water, Washington, DC, 2006a.
USEPA. National Recommended Water Quality Criteria, 4304T, Office of Water, Washington,
DC, 2006b. (http://www.epa.gov/waterscience/criteria/nrwqc-2006.pdf)
Wilkin, R. T. 2006. Mineralogical Preservation of Solid Samples Collected from Anoxic
Subsurface Environments, EPA Issue Paper, U.S. Environmental Protection Agency, Cincinnati,
OH, EPA/600/R-06/112. (http://www.epa.gov/ada/download/reports/epa 600 r02 002.pdf)
Wilkin, R. T. and Ford, R. G. 2006. Arsenic solid-phase partitioning in reducing sediments of a
contaminated wetland. Chemical Geology, 228(1-3): 156-174.
Final Report 30 September 2008 EPA/ORD
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922750
Sediment Pore Water
EPA/ORD Piezometer
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Figure 48. Location of push-point sampling locations for collection of sediment pore water
within Red Cove during September 2005. Locations of EPA/ORD piezometers and Army wells
shown for reference.
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922750
922650
192200 192250
Easting (m)
Figure 49. Location of sampling locations for collection of sediment cores within Red Cove
during September 2005 (transects "T02" and "T03") and April 2007 (transect "T01"). Locations
of EPA/ORD piezometers and Army wells shown for reference.
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922800
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922650
192200 192250
Easting (m)
192300
Figure 50. Location of sediment cores (pink crosses) relative to locations of temperature button
transects (filled yellow circles) installed in sediments within Red Cove.
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Easting (meters)
HCO, (mg/L)
0
50
100
150
200
250
300
350
400
1
3
5
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Easting (meters)
Figure 51. Spatial pattern in sediment pore water chemistry approximately 2 feet below the sediment surface in Red Cove based on
contouring of chemical data collected by push-point sampling during September 2005. Individual concentrations are shown in blue
text next to the push-point sample location and contoured concentrations throughout the cove are shown in black text.
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Figure 52. Concentration of iron (Fe, wt%) in the core section retrieved from the sediment surface for cores collected by EPA/ORD in
Red Cove during September 2005 and April 2007 (left panel). Isoconcentration contours were developed from individual data.
Locations for RCTW wells and surface water sampling are also shown. Relationship between solid phase iron and arsenic for shallow
sediments and the suspended solids collected from surface water sampling location SW02B (right panel).
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B
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102
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As(V) Co-precipitated with Ferrihydrite
Asflll) Co-precipitated with Ferrihydrite
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Amorphous Orpiment
Arsenopyrite
11860 11880 11900
Energy (eV)
11920
Figure 54. Basis set of XANES spectra for arsenic model compounds used in fitting sample
spectra from sediment cores retrieved from Red Cove during September 2005 (Transects 2 and
3) and March 2007 (Transect 1). Arsenopyrite is a natural mineral specimen, while the
remaining model compounds were synthesized in the laboratory using published procedures
(Ford et al., 2006; Wilkin and Ford, 2006).
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103
101
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Figure 55. Results from the speciation of arsenic by XANES analysis for sediment core locations along Transect 1 (see Figure 49).
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104
201 201 B 202 203 204
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Figure 56. Results from the speciation of arsenic by XANES analysis for sediment cores located along Transect 2 (see Figure 49).
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105
n
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As (mg kg-1sediments)
Ferrihydrite I I As(lll) Ferrihydrite I I As(lll) Pyrite As(lll)
Figure 57. Results from the speciation of arsenic by XANES analysis for sediment cores located along Transect 3 (see Figure 49).
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I As(V) Ferrihydrite
I As(lll) Ferrihydrite
I As(lll) Pyrte
! As(lll) Mackmawite
229 mg kg'1
S25im|k
-------
107
Part. As
Diss. As
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0 200 400 600 800 55 60 65 70
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I i I i I i I i I I i I i I i I
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- 5.0
Sediment
RCTW9
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20 40 60
Figure 59. Water quality data at surface water sampling locations SW02B and SW02A for April
2007. Data for closest RCTW well sampled on April 27, 2007 shown for reference.
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'w
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700 -
600 -
500 -
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Elements
(mg/kg)
As
Cr
Cu
Hg
Ni
Pb
Zn
6533
ND
41
ND
14
179
Figure 60. Mineralogical characterization of suspended solids recovered from the water column
in Red Cove at the SW02 sampling location (0.57 feet above sediments; ft bws = feet below
water surface; ND = not detected). Solids were collected on pre-weighed 0.2 |im membrane
filters by pumping directly from the sampling depth through an in-line filter housing; five
separate 200-mL samples filtered at a pumping rate of approximately 50 mL/min. The mass
concentration of total suspended solids was determined to be 39.8 ฑ4.1 mg/L (n=5). All solids
were composited for analysis by X-ray diffraction (top panel; Q = quartz); major and minor
element concentrations determined by difference for unfiltered and filtered (0.45 |im) water
samples. Photograph was taken from the pontoon boat at seepage meter deployment adjacent to
SW02B sampling location.
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-D- Part. As (ng/L)
Diss. As (ng/L)
0 200 400 600 800 55
i . i . i . i . i
^Temp(F)
60 65 70 0
Diss. K (mg/L)
Fe2+ (mg/L)
Part. Fe (mg/L)
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-2.0
-3.0
Sediment
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Aquifer
-5.0
-O- Sp. Cnd. (nS/cm)
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0 2 4 6 8 0 30 60 90 120150180
--Turb. (NTU)
pH(S.U.)
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0 200 400 600 800 55 60 65 70
0.0 I i I i I i I i I I i I i I i I
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2.0
3.0
4.0
5.0
6.0
7.0
o.o Water Surface
1.0
2.0
_ 3.0
Sediment
4.0
5.0
6.0
o o o o o o
o o o o o
(N fN * CD 00
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30 60 90 120 150
7.0
RCTW1
Figure 61. Water quality data at surface water sampling locations SW02B and SW03 for August
2007. Data for closest RCTW wells sampled during August 21-23, 2007 are shown for
reference.
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o.o
-D- Part. As
Diss. As (|ig/L)
0 200 400 600 800 55
I i I i I i I i I I
Temp (F)
o.o Water Surface
Sediment
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6.0
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40
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60
Sp. Cnd. (|iS/cm)
ORP (mV)
pH (S.U.)
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Turb. (NTU)
Part. Fe (mg/L)
Fe2+ (mg/L)
0 200 400 600 800 55 60 65 70
1,1,1,1,1 1,1,1,1
1.0 -
2.0 -
3.0 -
4.0 -
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- 5.0
- 6.0
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- 7.0
RCTW7
60
Figure 62. Water quality data at surface water sampling locations SW04 and SW05 for
September 2007. Data for closest RCTW wells sampled during August 21-23, 2007 are shown
for reference.
Final Report
30 September 2008
EPA/ORD
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Ill
SW02A, Apr 2007
SW02B, Aug 2007
SW03, Aug 2007
O PPT, Sep 2005
O TW, 2006-2007
Measurements conducted
at sediment surface.
8 0
PH
I ' I ' I ' I
2 4 6 8 10
DO (mg/L)
Figure 63. (Left) Comparison of measured water chemistry relative to stability fields for
ferrihydrite [represented as Fe(OH)3], pyrite (FeS2), and mackinawite (FeS). Platinum electrode
readings of oxidation-reduction potential (ORP) were converted to electron activity based on
reference to the standard hydrogen electrode. Stability fields were constructed as binary
systems, i.e., Fe(OH)3-FeS2 and Fe(OH)3-FeS. Data points enclosed within a red circle are for
measurements in which the YSI sonde was allowed to come in contact with sediments. Based on
platinum electrode measurements, these shallow sediments displayed the lowest ORP relative to
all other groundwater and surface water measurements. (Right) Dissolved oxygen concentration
measured as a function of depth below water surface. PPT = push-point samples, RCTW =
tubing wells completed in shallow aquifer underlying sediments
Final Report
30 September 2008
EPA/ORD
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112
O SW, 2006-2007
O PPT, Sep 2005
RSK 10/19, 2006-2007
5.0
5.5
Figure 64. Relative stability of low-temperature sulfide mineral forms of iron (FeS) and arsenic
(AS2S3, poorly crystalline) based on comparison of measured water characteristics (pH, ferrous
iron, arsenite concentrations) to thermodynamic predictions. The gray planar surface shown in
the figure is based on the chemical reaction expression 3FeS(S) + 2As(OH)3ฐ + 6H+ = As2S3(S) +
3Fe + + 6H2O (Wilkin and Ford, 2006). For surface water, only data for monitoring points <1.5
ft above the sediment surface are shown; depths > 1.5 ft above sediments are not reasonably
represented by this expression due to higher dissolved oxygen concentrations. Chemical
conditions for RSK 10 and RSK 19 well screens also shown to represent most reducing
conditions (low sulfate, high ammonia) observed in aquifer prior to discharge to Red Cove. PPT
= push-point samples
Final Report
30 September 2008
EPA/ORD
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113
1000
800
A Surface Water
A Push-Point
200 400 600
D ssolved As
800 1000 0.1
1000
As(lll):As(V)
Figure 65. Comparison of the measured concentrations of dissolved arsenic and the arsenite
[As(III)] chemical species in filtered push-point and surface water samples from Red Cove (left
panel). The line represents a direct linear correlation between the two measurements. The mass
ratio of As(III) and As(V) is shown as a function of depth below water surface (ft bws) for
surface water samples collected from Red Cove (right panel). Sample location and date (e.g.,
SW02A 0407 for April 2007) is shown for each data point.
Final Report
30 September 2008
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114
90000
18000
'P 1ROOO
LL
O) 14000
5* 19000
tr\ 1 0000
m 8000
CD
= 6000
o
1= 4000
Q_
2000
n
I
<
/j
fir
1
I
r
o
/
3ฐ
J
^^
. -
^ '
3
Red Cove
Suspended Solids
rmgx=1 9787 mg As/kg Fh
K= 13.2 L/mgAs
-
10
I -
F I
CD
LL 1
CD E
_CO
O
r? 0 1
n u. i
n n-i
i
L
i
'
c
'
A
ฃ A
^
V
(
[
ป
ฐ
A
A
4
10
: D
w'
w
o
1 5;
- ' (D
: Q-
I TI
(D
^
^ ' 3
: CQ
n n-i
U I I I I I ซซ ' I I I I I ซซ '
0 100 200 300 400 500 0 10 20 30 40 50
Dissolved As (ug/L) Dissolved Fe (mg/L)
Figure 66. Evaluation of arsenic sorption data for suspended solids within the Red Cove water column for sampling locations
SW02A, SW02B, SW03, SW04 and SW05. Particulate concentrations of arsenic and iron were determined by difference for
unfiltered and filtered (0.45 |im) samples. Data describing arsenic partitioning (left panel) were fit with a Langmuir isotherm; values
for maximum sorption capacity (rmax) and sorption coefficient (K) are shown based on a best fit regression. Fh = ferrihydrite (nominal
formula weight = 480 g/mole as Fe5HO8' 4H2O).
Final Report
30 September 2008
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115
RSK Linear Trend
o RCTW 2006
RCTW 2007
Deep SW 2006-2007
50
- 40
- 30
O)
E,
O
30
Na (mg/L)
K (mg/L)
Figure 67. Measured concentrations of chloride (Cl), sodium (Na) and potassium (K) for deep surface water samples and shallow
groundwater sampled from RCTW wells during 2006-2007. Values shown for deep surface water were interpolated from existing
data for a consistent height above the sediment surface of approximately 0.6-0.7 feet; actual concentrations change with proximity to
sediment (see Appendices). For comparison, linear trend fits to RSK groundwater data shown in Figure 32 are included, along with
the range of concentrations observed for well clusters RSK 1-7, RSK 16-20 and RSK 8-12. The range in concentration for Red Cove
surface water samples (shallowest depth; Figure 34) collected during 2006 and 2007 are shown for reference as the light-gray hatched
area.
Final Report
30 September 2008
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116
922710-
922700 -
'V)
0 922690 -
O)
922680 -
"g 922670 -
922660 -
922650
K(mg/L)
August 2006
K(mg/L)
August 2007
A4.3
RCTW
Deep SW
Cove Perimeter
n^ r/*0 o^^'0 otfP o^^ ct&
>$!> Nq^ Nq^^ Nq^*- Nq^*- Nq^*-
Easting (meters)
^ x x x x X X
Easting (meters)
o
2
4
6
8
10
12
14
Figure 68. Distribution of potassium (K) concentrations in shallow groundwater (RCTW wells) and deep surface water above the
sediment surface in Red Cove. Isoconcentration contours were developed using the measured values at RCTW wells (blue text).
Measured values for all surface water sampling locations (2006-2007) are shown in black text on the right panel.
Final Report
30 September 2008
EPA/ORD
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117
922720
922700 -
922680 -
O)
-c
O
922660 -
922640
I
I
I
I
K (mg/L) Aug 21-23, 2007
Temp Buttons
A SW (64.5-69.6 F) & 50-5 ฑ ฐ-2 F
o RSK r/ \ A
o RCTW ^/^rr-^TN-^vx^
/ IVS^Ls*
RSK 16-20 ฎ>
52.0 ฑ 0.4 F
RSK 8-12
<ง>
52.5 ฑ 0.2 F
RSK 13-15
6 49.4 ฑ 0.4 F
RSK 37-42
\ 'I 'I ' I
192180 192200 192220 192240
Easting (meters)
Aug 22, 2007
50
64
GW
52
54
CD
55 5T
I
7 3;
59 2
62
SW
Figure 69. Comparison of sediment temperature distribution (August 22, 2007) to contoured
potassium concentrations (mg/L) in RCTW wells measured during August 21-23, 2007. The
relative influence from groundwater and surface water on observed sediment temperatures is
estimated based on the color gradation shown to the right of the plot. Shown for reference are
groundwater temperatures for RSK well screens completed near the water table for the period
July 22 - August 22, 2007 (mean ฑ standard deviation). Temperature data were not available for
RSK 37-42 well cluster location, but during the period Sept 13 - Oct 13, 2007 temperatures were
55.2ฑ0.1F.
Final Report
30 September 2008
EPA/ORD
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118
(/)
<
1000
800
600
400
9DD
0 -
c
A Deep SW 2006-2007
v Shallow SW 2006-2007
o RCTW 2006
RCTW 2007
)
V^
ORCTV
4S>No6
/6
AC
SM403
SM4<#^
3RCTW8
*ซ**
RCTW6
0 0
<*$$&-
2468
o
/
o Ch
0
o
i
\cute AV\/
ronicA\A
MCL
10 12 1
'QC
'QC
4
K (mg/L)
Figure 70. Comparison of arsenic (As) and potassium (K) concentrations for deep and shallow
surface water in Red Cove to concentrations observed in underlying shallow groundwater
(filtered, 0.45 |im). Values shown for deep surface water were interpolated from existing data
for a consistent height above the sediment surface of approximately 0.6-0.7 feet; actual
concentrations increase with proximity to sediment (see Appendices). Shallow surface water
data are for depths below water surface of <0.5 feet. MCL = Maximum Contaminant Level,
AWQC = Ambient Water Quality Criterion
Final Report
30 September 2008
EPA/ORD
-------
922710-
922700 -
CO
X 922690-^
CD
922680 -
922670 -
922660 -
\oP
i i i
1800>O 310
1767
o
2000
RCTW As Contours
August 2006
Easting (meters)
O Historical PSP Sediment (mg/kg As)
RCTW
^Cove Perimeter
119
922710-
922700 -
922690 -
RCTW As Contours
August 2007
922680 -
922670 -
922660 -
Arsenic
(H9/L)
0
Easting (meters)
O EPA/ORD Sediment (mg/kg As)
^ Deep SW (ng/L As)
RCTW
^^ Cove Perimeter
Figure 71. Comparison of arsenic concentrations in sediment, deep surface water and shallow groundwater in Red Cove. Historical
sediment data collected for Plow Shop Pond shown in the left panel (Gannett Fleming, 2006). Sediment and surface water data
collected by EPA/ORD shown in the right panel. Contoured concentrations are for shallow groundwater based on data from RCTW
wells.
Final Report
30 September 2008
EPA/ORD
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922720
922710 -
922700 -
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121
Table 9. Concentration of arsenic and speciation of the arsenic solid phase as determined by
linear combination fitting of XANES data for Transect 1.
Core
1
2
3
Depth
(in)
3.5
7
10.5
14
16
3.5
7
10.5
14
3.5
7
10.5
14
16
As
(mg kg"1)
3260
1440
703
52.6
8.2
2900
1710
1470
245
6940
2150
1370
232
11.6
Arsenic Species (Percent)
As(V)-Fh
54
36
27
30
60
37
33
26
24
77
17
33
43
60
As(III)-Fh
46
58
16
51
38
63
15
12
44
23
44
24
42
32
As(III)-py
0
6
57
19
2
0
53
61
32
0
40
42
15
8
As(III)-mack
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Final Report 30 September 2008 EPA/ORD
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122
Table 10. Concentration of arsenic and speciation of the arsenic solid phase as determined by
linear combination fitting of XANES data for Transect 2.
Core
1
IB
2
2B
o
3
Depth
(in)
2
4
6
8
10
12
14
2
4
6
8
10
12
14
16
18
20
22.25
2
4
6
8
10
12
14
16
18.5
2
4
6
8
10
12
14
17.5
21
24.5
28
32
36
40
2
4
6
8
10
12
15.5
19
As
(mg kg'1)
459.0
229.0
30.4
16.6
15.0
18.7
22.7
825.0
76.2
33.5
20.2
15.7
16.0
15.0
13.6
11.5
11.3
10.7
8600
6490
4080
4160
2260
1340
588
326
322
1180
669
649
646
145
32.7
26.8
12
12.5
12.7
13.5
24.2
12.4
23.2
137.0
112.0
79.3
15.6
14.7
24.8
9.1
9.9
Arsenic Species (Percent)
As(V)-Fh
-
8
6
12
5
6
13
5
14
17
20
-
-
27
35
31
-
38
15
43
39
29
25
26
14
33
13
15
17
16
7
18
9
-
65
-
71
71
73
39
53
26
9
30
25
-
34
66
67
As(III)-Fh
-
86
71
88
95
94
87
88
32
77
69
-
-
73
65
69
-
62
77
50
45
12
21
12
11
26
66
19
13
9
7
17
25
-
35
-
29
29
27
61
47
26
16
15
75
-
66
34
33
As(III)-py
-
7
23
0
0
0
0
7
54
6
10
-
-
0
0
0
-
0
8
7
16
35
11
o
J
17
41
20
66
70
75
86
65
65
-
0
-
0
0
0
0
0
31
30
55
0
-
0
0
0
As(III)-mack
-
0
0
0
0
0
0
0
0
0
0
-
-
0
0
0
-
0
0
0
0
24
43
59
58
0
0
0
0
0
0
0
0
-
0
-
0
0
0
0
0
17
45
0
0
-
0
0
0
Final Report
30 September 2008
EPA/ORD
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123
22.5
26
29.5
33
36.5
40
4 2
4
6
7.125
11.125
15.125
19.125
22.625
26.125
29.625
33.125
10.7
11.3
14.8
18.3
21.8
25.3
1310
1670
1510
397
183
10.1
9.65
-
-
-
-
48
40
70
70
71
71
8
9
11
9
43
44
41
-
-
-
-
52
60
30
30
29
29
92
91
89
91
43
42
31
-
-
-
-
0
0
0
0
0
0
0
0
0
0
13
14
28
-
-
-
-
0
0
0
0
0
0
0
0
0
0
0
0
0
-
-
-
-
Final Report 30 September 2008 EPA/ORD
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124
Table 11. Concentration of arsenic and speciation of the arsenic solid phase as determined by
linear combination fitting of XANES data for Transect 3.
Core
1
2
3
Depth
(in)
2
4
6
8
10
12
13
16.5
20
23.5
27
2
4
6
8
10
10.5
14
17.5
21
24.5
1
3
5
7
9
11
13
15
15.5
17.5
19.5
21.5
23.5
25.5
27.25
29.25
31.25
33.25
35.25
37.25
39.25
As
(mg kg'1)
2540
1710
930
850
556
36.8
19.7
17.9
25.7
24.3
22.4
248
143
92.3
22.4
15.7
16.4
20.1
12.9
14.2
8.91
464.0
51.0
18.3
9.5
8.3
9.0
10.0
11.3
266.0
287.0
244.0
193.0
54.0
27.4
35.7
44.9
28.6
26.1
22.1
15.4
15.4
Arsenic Species (Percent)
As(V)-Fh
12
12
5
0
0
-
-
28
38
48
53
13
9
9
8
15
25
47
52
68
70
14
33
-
-
-
-
-
-
17
13
8
0
29
29
41
45
35
-
44
17
-
As(III)-Fh
88
82
62
76
60
-
-
65
62
52
47
83
69
91
92
85
75
53
48
32
30
86
67
-
-
-
-
-
-
61
82
89
89
63
71
59
55
65
-
56
83
-
As(III)-py
0
5
33
24
40
-
-
6
0
0
0
4
22
0
0
0
0
0
0
0
0
0
0
-
-
-
-
-
-
22
5
o
J
11
7
0
0
0
0
-
0
0
-
As(III)-mack
0
0
0
0
0
-
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
-
-
-
-
-
0
0
0
0
0
0
0
0
0
-
0
0
-
Final Report 30 September 2008 EPA/ORD
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125
5 Summary and Recommendations
The following sections provide a summary of existing conditions maintaining elevated levels of
arsenic within Red Cove, an assessment of remedial alternatives that may be employed to
address groundwater and sediment contamination, and recommendations for additional site
characterization efforts needed to support evaluation of remedial alternatives for site restoration.
Discussion of remedial alternatives for groundwater and sediment cleanup is for information
purposes only.
5.1 Red Cove - Existing Conditions
Analysis of hydrologic and chemistry data collected from the Red Cove Study Area during
September 2005 to November 2007 indicate that groundwater with elevated concentrations of
arsenic currently discharges into Red Cove. Based on current and historical data for the
distribution of arsenic in shallow sediments within Plow Shop Pond (Gannett Fleming, 2006),
the arsenic concentrations observed in Red Cove sediments appear consistent with groundwater
discharge as a source of arsenic contamination. The distribution of arsenic flux measured at
RSK well clusters in combination with the piezometric surface depicting groundwater flow
potential for the aquifer underlying the landfill (CH2MHill, 2006) indicate that the primary
source of arsenic originates from a direction west-southwest of Red Cove. Since the speciation
of arsenic is dominated by inorganic forms, there is no unique signature to differentiate whether
this contamination is due solely to materials disposed within the landfill, due solely to the result
of landfill-induced reducing conditions liberating natural sources of arsenic in overburden, till or
bedrock, or some combination of these factors.
Comparison of water chemistry data from well screens installed within the aquifer underlying the
central portion of the landfill indicates that mixing of groundwater near the water table (N5-P2
completed in disposed material) and at depth within the overburden (SHP-99-29X) or bedrock
groundwater (N5-P1) provides a reasonable match to chemical conditions observed throughout
the saturated overburden thickness at RSK well cluster RSK 8-12 (See Section 3.2). In contrast,
the water chemistry observed at well screens installed within the southern portion of the landfill
(N7-P1,P2) does not provide a reasonable match to the water chemistry observed at RSK well
clusters RSK 8-12 and RSK 16-20 (see Figures 40 and 41). However, based on the groundwater
piezometric surface determined within the boundary of the landfill (CH2MHill, 2006), there is
not a likely flow path from groundwater at well locations N5-P1,P2 and SHP-99-29X to the RSK
8-12 and RSK 16-20 well clusters. Thus, the elevated concentrations of arsenic observed at
these RSK well clusters appears to originate from a portion of the aquifer between the aerial
locations of existing wells N5-Pl,P2/SHP-99-29X and N7-P1,P2. In addition, the water
chemistry observed at existing locations N5-P1,P2 and SHP-99-29X may, in part, reflect flow
contributions from groundwater originating further upgradient within the aquifer underlying the
landfill. Currently, insufficient groundwater characterization data are available to further
delineate the source of the arsenic plume discharging to Red Cove.
Presently, concentrations of arsenic observed in surface water within Red Cove are, in part,
controlled by the continual precipitation of iron oxides that sequester dissolved arsenic
introduced from groundwater discharge or released by diffusion from contaminated sediments.
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126
Since the cove is a biologically productive system due to the continual, seasonal supply of
degradable organic matter from aquatic plants, reducing conditions will likely prevail at the
sediment-surface water interface. As previously shown in Figure 63, the lowest ORP readings
for Red Cove Study Area wells sampled for chemistry data were observed within the shallow
sediment layer. Thus, while the continual oxidation and precipitation of ferrous iron within the
water column will serve to remove a portion of dissolved arsenic from the water column, the
precipitated iron oxides are susceptible to re-dissolution and release of sequestered arsenic. This
process appears to occur at surface water sampling location SW04 where sequestration of
dissolved arsenic is active, as indicated by the high turbidity near the sediment-surface water
interface and the high shallow sediment arsenic concentrations at sediment core locations
SCT0102 and SCT0103 (Figure 71).
The concentration of potassium in surface water samples can be used as a tracer for
contaminated groundwater discharge. Comparison of potassium concentrations in deep surface
water at SW04 (2.4 mg/L; Figure 68) and shallow groundwater at TW10 (11.3 mg/L; Figure 68)
indicates that groundwater discharge does not likely control arsenic concentrations in surface
water at location SW04. Rather, the dissolved (0.45 |im filtered) arsenic concentrations
observed in deep surface water are most likely derived from the release of arsenic during
dissolution of the iron oxides deposited in shallow sediments (Figure 73). As a point of
reference, the concentration of potassium in deep surface water at sampling locations MC and
SW02B ranged between 8.8-10.3 mg/L (May 2006, Aug 2007) compared to 11.8-13.4 mg/L and
12.1-12.4 mg/L at shallow groundwater locations RCTW4 (Aug 2006, Aug 2007) and RCTW9
(Aug 2006, Apr 2007), respectively. According to solid phase speciation data for shallow
sediments near location SW04, arsenic predominantly resides as As(III) or As(V) associated with
an iron oxide, similar to the precipitate settling out from the overlying water column (Figure 58).
This pattern in arsenic recycling between contaminated sediments and overlying surface water at
location SW04 is similar to that observed for a eutrophic, kettle-hole lake near Arlington,
Massachusetts (Senn et al., 2007). The objective of that field study was to examine the long-
term fate of a historical pulse of arsenic that ultimately became associated with sediments. In the
study conducted by Senn et al. (2007), characterization of the system indicated that a majority of
the contemporary arsenic load within the water column was derived from dissolution of
contaminated sediments.
The result of this internal recycling of arsenic between sediments and overlying surface water is
the potential maintenance of dissolved arsenic concentrations within the water column that may
exceed ambient water quality criteria. Thus, the contaminated sediments could pose a long-term
exposure risk to aquatic life within Red Cove surface water. The actual impact to aquatic life
would need to be tested via exposure tests designed to replicate in-situ conditions within the
cove. In general, the following statements can be made concerning the transport and fate of
arsenic entering Red Cove based on the information documented in this report:
The centerline of highest arsenic flux from groundwater discharging into Red Cove
appears to lie between RSK well clusters RSK 13-15 and RSK 1-7.
The chemistry of groundwater adj acent to Red Cove containing elevated concentrations
of arsenic is not consistent with the chemistry observed at any single screened interval for
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127
SHL wells N7-P1, N7-P2, SHP-99-29X, N5-P1 or N5-P2. Groundwater chemistry at
well clusters with highest calculated arsenic flux (RSK 8-12 and RSK 16-20) appear to be
derived from a mixture of sources and/or locations under the landfill between existing
well locations N7-P1,P2 and N5-P1,P2 that are currently not monitored for chemistry.
Measurements of shallow groundwater chemistry underneath Red Cove along with direct
measurements of groundwater discharge demonstrate that the existing groundwater
extraction system does not prevent arsenic plume discharge into the cove at current
pumping rates.
The highest concentration of arsenic in surface water within Red Cove was observed at a
known location of groundwater discharge.
Oxidation and precipitation of ferrous iron within surface water sequesters a portion of
arsenic derived from groundwater discharge and/or contaminated sediment dissolution.
Elevated concentrations of arsenic in deep surface water within zones where
contaminated groundwater discharge appears less significant indicates that arsenic
sequestered by settling iron oxide precipitates is not stable under existing conditions.
Remediation of existing contaminated sediments within Red Cove will have limited long-
term effectiveness if conducted without remediation of the groundwater plume
discharging into the cove.
5.2 Analysis of Potential Remediation Alternatives
The relationship between groundwater discharge and sediment contamination in Red Cove is a
critical issue that impacts possible approaches to address contaminated sediments in this portion
of Plow Shop Pond.
The continued flux of arsenic anticipated from groundwater discharge into Red Cove will
influence the effectiveness of any remedy evaluated or selected to address sediment
contamination. It is not likely that any chosen remedy for contaminated sediments will have
sufficient long-term effectiveness without significant reduction or elimination of contaminated
groundwater discharge. Thus, it is important to first consider remedial approaches to address
contaminated groundwater discharging into Red Cove.
5.2.7 Groundwater
There are two general approaches to address contaminated groundwater discharge to Red Cove:
1) eliminate discharge by changing the prevailing flow gradient or 2) in-situ removal of arsenic
from groundwater prior to discharge to the cove. Current performance data for the groundwater
extraction system at the northern end of Shepley's Hill Landfill suggest that this type of
approach may be applied in the vicinity of Red Cove. Direct measurements of groundwater
discharge into Red Cove indicate that current pumping rates at the northern end of the landfill are
insufficient to prevent the continued flux of arsenic discharging into the cove (Section 2.5). This
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128
is demonstrated by the continued observation of groundwater discharge into the cove at
advective flux meter location SM1B from April 2007 to November 2007 even though the rate of
groundwater extraction was increased from approximately 20 gpm to a sustained rate greater
than 40 gpm during July 2007. It is likely that the existing groundwater extraction system would
need to be supplemented to target increased capacity for extraction adjacent to Red Cove. The
detailed information on local flow gradients around Red Cove and the spatial distribution of
arsenic flux provided in this report present a sound basis for delineation of the dimensions and
centerline of the groundwater plume along the eastern border of the landfill cap. More detailed
mapping of the arsenic plume to the west-southwest of well clusters RSK 8-12 and RSK 16-20
would facilitate designing a supplemental extraction system that targets the most severe sources
of contaminated groundwater discharge. Alternatively, a slurry wall or some other form of
containment could be constructed to re-direct groundwater flow from Red Cove towards the
existing extraction system.
In addition to implementing controls on groundwater hydrology adjacent to Red Cove, it may
also be feasible to minimize arsenic discharge through manipulation of the geochemical
conditions within the unconsolidated aquifer underlying Shepley's Hill Landfill. In general, the
reducing conditions in groundwater maintain iron in a soluble form and prevent precipitation of
iron oxide minerals prior to discharge into Red Cove. One potential approach to induce more
oxidizing conditions and maintain iron in less soluble forms could involve re-introduction of
treated, oxidized water from the existing pump and treat system back into the aquifer underlying
the landfill and/or immediately upgradient from the zone of discharge into Red Cove. This may
necessitate development of a more detailed knowledge of groundwater flow within the landfill to
support analysis for design of an appropriate infiltration system for re-introduction of treated
groundwater.
Alternatively, in-situ removal of arsenic in groundwater, without additional hydrologic control,
appears feasible through use of a permeable reactive barrier (PRB) system installed
perpendicular to the discharge of contaminated groundwater. By positioning the PRB close to
the cove shoreline, the physical dimensions and associated capital costs of the installation could
be minimized. Bench and pilot tests with zero-valent iron indicate that this material would
provide a likely candidate as a reactive matrix for the PRB (Lien and Wilkin, 2004; Wilkin et al.,
2005; Ford et al., 2007). Long-term performance data for a zero-valent iron PRB installed under
similar groundwater geochemistry at the Elizabeth City site in North Carolina indicates
satisfactory long term performance characteristics, relative to barrier porosity and reactivity,
could be realized within the Red Cove Study Area. Relative to these performance
characteristics, zero-valent iron barrier systems demonstrate better performance characteristics
for groundwater with total dissolved solids (TDS) concentration <1000 mg/L (e.g., <600 mg/L
TDS at Elizabeth City site; Chapter 6 in Wilkin and Puls, 2003). A potential limitation of a zero-
valent iron PRB is the generation of more reducing and higher pH conditions downgradient of
the barrier, which may result in greater instability of existing contaminated sediments impacted
by historical groundwater discharge. Thus, a PRB may necessitate some form of active
management of sediments and/or surface water conditions within Red Cove in order to avoid
further degradation of conditions supporting aquatic life in this portion of Plow Shop Pond.
Performance data are not available for barrier systems employing reactive media that do not
exert a strong influence on redox geochemistry within and downgradient of the barrier system.
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129
5.2.2 Sediments
Existing information is insufficient to define the absolute contribution of contaminated sediments
to the concentration of arsenic observed in deep surface water within Red Cove. In general, iron
oxides precipitated in the water column will be unstable in the reducing conditions encountered
following re-deposition onto sediments in Red Cove. As a point of reference, surface water
sampling locations SW04 and SW05 appear to have limited influence from direct groundwater
discharge. However, the concentration of dissolved arsenic in deep surface water at these
locations ranged between 45-136 |ig/L. The deposition and decay of organic material from
aquatic plants and other natural sources within Red Cove will tend to maintain reducing
conditions within shallow sediments even in the absence of the discharge of reducing
groundwater. The extent that this natural process drives observed conditions within Red Cove
currently cannot be assessed with reliability given the influence of contaminated groundwater
discharge. It is reasonable to assume that historical accumulation of arsenic in sediments in Red
Cove will continue to provide a potential long-term source of arsenic to overlying surface water,
but this is poorly defined at present. The range of dissolved arsenic concentrations due to release
from contaminated sediments at surface water sampling locations SW04 and SW05 appear to be
lower than those observed at a known location of contaminated groundwater discharge (107-506
|ig/L at locations MC and SW02B). However, these data are insufficient to define the flux of
arsenic attributed solely to release from contaminated sediments.
Given the constraints of this analysis, there appears to be at least two options that may be
employed to remediate sediment contamination. Provided cessation of contaminated
groundwater discharge, removal of existing contaminated sediments provides a direct approach
to eliminate the contaminant burden within the cove. Based on the depth distribution of arsenic
within sediment cores, removal to a depth of approximately 15 inches below the existing
sediment surface should be sufficient to eliminate a majority of the current mass of arsenic tied
up in sediments. However, it is unclear whether this level of disturbance to the existing benthic
habitat provides an acceptable remedial approach relative to a desired ecosystem restoration
endpoint.
Additionally, it is reasonable to consider placement of clean material on top of contaminated
sediments to provide additional capacity to sequester arsenic released from contaminated
sediments and to provide improved benthic habitat. The solid material in a "reactive" cap would
need several characteristics to optimize its performance: 1) capacity and selectivity for arsenic
sorption in the presence of a range of dissolved constituents common to groundwater and surface
water at Red Cove, 2) stability to resist dissolution due to the development of reducing
conditions, and 3) permeability sufficient to prevent the potential redirection of discharging
groundwater to regions further out into Plow Shop Pond. There is limited information on
reactive sediment capping materials designed to sequester contaminants with chemical
characteristics like arsenic. Thus, some developmental work would be necessary to identify a
suitable material. In addition, this approach provides the ability to place clean solid substrate on
top of the newly emplaced "reactive" material in order to improve benthic habitat.
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130
These approaches provide alternatives to minimize release of dissolved arsenic to overlying
surface water, thus minimizing potential exposure routes within the water column. As
previously discussed, sediment removal may result in unacceptable disturbance to the benthic
habitat and would likely require further effort to stabilize arsenic bound to the sediments or
necessitate disposal of dredged sediment as a hazardous material. Likewise, increasing the
stability of arsenic-bearing iron oxides within the sediment will not necessarily address routes of
exposure to the benthic community within Red Cove. Thus, it is recommended that an exposure
assessment be conducted that is designed to assist differentiation of the risk attributed to
dissolved arsenic (or other potential risk drivers such as ammonia) versus arsenic associated with
contaminated sediments. This information would also be critical to the evaluation of whether
monitored natural recovery (MNR) provides a viable long-term alternative for contaminated
sediments. The effectiveness of this remedial approach cannot currently be assessed given the
continued influence of contaminated groundwater discharge into the cove.
5.3 Recommendations for Site Characterization
There are four issues that merit continued site characterization efforts to support evaluation of
the performance of the existing pump and treat groundwater remedy and to support selection of a
remedy for contaminated sediments in Red Cove. These issues are listed below along with
recommendations for who could lead this effort:
1) Further delineation of the spatial extent of the arsenic plume discharging into Red Cove
in order to support design of a better targeted and cost-efficient remedial system to
minimize or eliminate contaminated groundwater discharge into the cove;
Sample groundwater chemistry at water table closer to eastern edge of landfill cap to
supplement aerial coverage of existing RSK and Army wells (EPA/ORD - RSK 26,
27, 28, 29, 30, and 32)
Sample groundwater chemistry at discrete depths throughout the saturated overburden
down to bedrock within SHL of at least three locations (Figure 74A) to characterize
groundwater chemistry in saturated waste and unconsolidated aquifer between
locations of existing wells N7-P1,P2 and N5-P1,P2 (Army; EPA/ORD sample splits
for supplemental chemistry, if desired). Where feasible, collection of solids as a
function of saturated depth is recommended in order to examine the potential
correspondence between arsenic content in groundwater and co-located aquifer solids.
[Adjustment to these proposed locations may be warranted with acquisition and
review of additional hydrologic or chemistry data from the existing monitoring well
network.]
Sample groundwater chemistry at discrete depths throughout the saturated overburden
down to bedrock along the eastern edge of landfill cap at two locations as illustrated
in Figure 74B (Army; EPA/ORD sample splits for supplemental chemistry, if
desired). [Adjustment to these proposed locations may be warranted with acquisition
and review of additional hydrologic or chemistry data from the existing monitoring
well network.]
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131
2) Continued assessment of the influence of the existing groundwater extraction system on
potentiometric surface and flow gradients adjacent to Red Cove and discharge patterns
into Red Cove (EPA/ORD). Conduct advective flux measurements in additional
locations of the cove and further assess use of sediment temperature measurements to
map out areas of groundwater discharge (EPA/ORD). Given the importance of local
rainfall events on system hydrology, it is also recommended that an on-site
meteorological station be installed and monitored in order better constrain interpretations
of water level fluctuations in the aquifer (Army);
3) Evaluation of existing data and determination of supplemental sampling locations needed
to design and complete an aquatic and human health exposure assessment study that
targets locations within the cove that will assist in assessing the separate contributions of
contaminants derived from groundwater discharge versus existing contaminated
sediments (Army); and,
4) Acquisition of additional depth-resolved surface water data to better map out the spatial
distribution of redox conditions and dissolved contaminants within the water column
(EPA/ORD).
The first issue is warranted to improve the effectiveness and cost-efficiency of a remedial system
to intercept contaminated groundwater discharge to Red Cove. According to groundwater
chemistry data from the Red Cove Study Area, the centerline of highest arsenic flux adjacent to
Red Cove appears to be within the zone monitored at RSK well clusters RSK 8-12 and RSK 16-
20 (Figure 72). In order to optimize plume interception or groundwater extraction efficiency,
knowledge of the plume dimensions further to the west-southwest of Red Cove would provide
useful constraint for selecting the capacity and siting of the remedial system. It is recommended
that additional monitoring points (temporary or permanent) be sampled along the eastern edge of
the landfill cap to better delineate the horizontal and vertical extent of the plume that is the
source of elevated arsenic concentrations discharging into Red Cove.
The second issue is warranted given the relatively short period of time over which the existing
groundwater extraction system has been operating, particularly considering the operational
changes that have been implemented within the past year. This information is needed to better
evaluate the degree of influence this extraction system will have on groundwater potentiometric
surface adjacent to the cove. The existing hydrologic monitoring network should be sufficient to
accomplish this objective.
The third issue is warranted given the relatively sparse number of deployments of the advective
flux meter to directly map out contaminated groundwater discharge within the cove. Since
arsenic in sediment and surface water was identified as a potential contributor to unacceptable
risk in Plow Shop Pond (Gannett Fleming, 2006), determining the relative contribution of
exposure to groundwater discharge versus contaminated sediments for potential impacts to
aquatic life or human exposure is needed. The existing data offer a good basis for a map of
groundwater discharge within the cove, and future ORD work will be used to improve this
understanding of groundwater discharge areas. Specifically, additional measurements using the
advective flux meter in combination with additional temperature button deployments and water
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132
quality measurements will be used to develop a more detailed map of groundwater discharge
within Red Cove. The greater detail will assist in selecting locations for isolating the effects of
groundwater discharge and contaminated sediments on the response of potential receptors in the
pond.
The last issue is warranted given the uncertainty of whether acceptable contaminant
concentrations can be achieved in surface water overlying contaminated sediments with the
advent of more oxidizing conditions. Supplemental measurements are warranted in areas where
there appears to be limited current discharge of contaminated groundwater originating from the
landfill. These measurements should be coordinated with the effort to map out groundwater
discharge within the cove in order to reduce uncertainty in the interpretation of collected data.
5.4 References
ABB Environmental Services, Inc. (ABB- ES), 1995. "FortDevens Feasibility Study for Group
1A Sites, Final Feasibility Study, Shepley's Hill Landfill Operable Unit, Data Item A009".
Prepared for the U. S. Army Environmental Center, Aberdeen Proving Ground,
Maryland. Arlington, Virginia.
CH2MHill, 2006 Annual Report, Shepley's Hill Landfill Long Term Monitoring & Maintenance,
Devens, Massachusetts". Prepared for the Department of the Army, BRAC Environmental,
Devens, Massachusetts.
Ford, R. G, Kent, D. B., and Wilkin, R. T. 2007. "Arsenic", In Monitored Natural Attenuation
of Inorganic Contaminants in Ground Water: Volume 2 - Assessment for Non-Radionuclides
Including Arsenic, Cadmium, Chromium, Copper, Lead, Nickel, Nitrate, Perchlorate, and
Selenium, EPA Report, U.S. Environmental Protection Agency, Cincinnati, OH, EPA/600/R-
07/140. (http://www.epa.gov/ada/pubs/reports/600R07140.htmn
Gannett Fleming, Inc., 2006. "Final Expanded Site Investigation, Grove Pond and Plow Shop
Pond, Ayer, Massachusetts". Prepared for the U. S. Environmental Protection Agency, Region 1,
Boston, Massachusetts, (http://www.epa.gov/ne/superfund/sites/devens/246620.pdf)
Lien, H. L. and Wilkin, R. T. 2004. High-level arsenite removal from groundwater by zero-
valentiron. Chemosphere, 59: 377-386.
Senn, D. B., Gawel, J. E., Jay, J. A., Hemond, H. F., and Durant, J. F. 2007. Long-Term fate of a
pulse arsenic input to a eutrophic lake. Environmental Science and Technology, 41: 3062-3068.
Wilkin, R. T., Jacobson, L., and Coombe, E. 2005. Zero-valent iron PRB application expands to
arsenic removal. Technology News and Trends, Issue 21, pp. 1-2. (http://www.clu-
in.org/download/newsltrs/tnandtl 105 .pdf)
Wilkin, R. T. and Puls, R. W. 2003. Capstone Report on the Application, Monitoring, and
Performance of Permeable Reactive Barriers for Ground-Water Remediation: Volume 1 -
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133
Performance Evaluations at Two Sites, EPA Report, U.S. Environmental Protection Agency,
Cincinnati, OH, EPA/600/R-03/045a. (http://www.epa.gov/ada/pubs/reports/600R03045a.htmn
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134
225 -
t? 220^
< 215 -
*=;
c 210 -
o
ro 205 -
CD
UJ 200 -
RSK8-12
4
+
;i
i
^
1 1
192180
... ,ฃ ^r ^p g
RSK 16-20 '" """"ป ]
r.
,l ^ ':.':
1 00 q- m
T 5 ? ฃ
t ฃ ^
1 ' 1 ' 1 ' 1
192190 192200 192210 192220
A
^
1 !
CD :
O !
CC =
1
192230 192240
Easting (meters)
218 -
216 -
HT
CO
< 214 -]
c
o
^ 212 -I
_
LL)
210 -
208 -1
MC
SW02B
SW04
Sediment
RCTW4
RCTW9
RC Water Column
.:::- SW Locations
Land/Sediment Surface
ป RSK Wei Is
RCTW 10
I
192215
I
192220
I '
192225
Easting (meters)
192230
192235
t
GW Discharge
High Asf Fe, K
Sediment Recycling
High As, Fe - Low K
Figure 73. (Top Panel) Cross-section through Red Cove (RC) showing relative locations of RSK
and RCTW wells along with surface water (SW) sampling locations. (Bottom Panel) Zoomed
view from top panel showing locations of RCTW wells and neighboring surface water sampling
locations where arsenic concentration in deep surface water is dominated by contaminated
sediment dissolution (SW04) versus groundwater discharge (MC and SW02B). Elevated
potassium concentration in deep surface water is a signature of groundwater plume discharge.
Note that sediment dissolution may also contribute to arsenic at locations MC and SW02B.
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135
&23G0J-
S22200
191800
192000
192200
192400
Easting (m)
B
PZ9
RSK30
RSK32
RSK1B-21
"STAFFI
PZ3
RSK4I **
.SK36-43
RSK26
RSK24
.13-15
RSK49
Figure 74. Proposed locations (yellow dots) for collection of additional groundwater chemistry data (A) in saturated unconsolidated
aquifer within the Shepley's Hill Landfill (SHL) and (B) along the eastern edge of the landfill cap adjacent to Red Cove. Boundaries
of disposal units for SHL estimated from evaluation of Figure 1-4 in ABB-ES (1995) and locations of existing wells shown with red
dots around the perimeter of the landfill; other existing wells not used shown with white dots.
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136
APPENDIX A
SITE MAPS
Final Report 30 September 2008 EPA/ORD
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137
Red Cove Study Area
Figure A. 1. Map showing location of the Red Cove Study Area of Plow Shop Pond adj acent to Shepley' s Hill Landfill at the Fort
Devens Superfund Site (US ACE, 2006).
Final Report
30 September 2008
EPA/ORD
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138
Former Moore
Army Airfield
Ayer Rotary
(McDonald's,
Wendy's^
SHEPLEY'S HILL
LANDFILI
SHIRLEY
ii-.--~ฐ*^unW
Lancaster (Worซs~ C~n"yl
i AM^AOTCO Jackson Road
LANCASTER Interchange
HARVARD
Legend
Installation
Boundary
Town Line
Brook
Pond/Lake
Roads/Highway
Scale in Feet
ซr
0 3,000 6,000
Figure A.2. Map showing location of the Fort Devens Superfund Site (US ACE, 2006).
Final Report
30 September 2008
EPA/ORD
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139
APPENDIX B
LOCATION DATA
Northing and easting coordinates of wells were surveyed relative to the locations of existing wells at the SHL site.
The coordinates are reported in meters using the Massachusetts State Plane coordinate system and are reported
relative to the NAD83 datum. Elevations were surveyed relative to existing wells which are reported to use the
National Geodetic Vertical Datum of 1929.
Final Report 30 September 2008 EPA/ORD
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140
Table B.I. Well Locations and screened intervals.
Well
RSK1
RSK2
RSK3
RSK4
RSK5
RSK6
RSK7
RSK8
RSK9
RSK10
RSK11
RSK12
RSK13
RSK14
RSK15
RSK16
RSK17
RSK18
RSK19
RSK20
RSK21
RSK23
RSK24
RSK25
RSK26
RSK27
RSK28
RSK29
RSK30
RSK32
RSK33
RSK34
RSK35
RSK36
RSK37
RSK38
RSK39
RSK40
RSK41
RSK42
RSK43
RSK47
RSK48
RSK49
Northing
(m)
922710.63
922710.96
922711.38
922712.34
922711.72
922711.38
922711.92
922659.41
922659.84
922659.33
922658.95
922658.31
922648.82
922648.91
922648.26
922695.95
922695.87
922696.46
922696.56
922697.00
922696.83
922650.96
922616.98
922620.30
922635.27
922644.10
922667.84
922678.74
922702.92
922693.87
922761.13
922767.20
922788.58
922663.22
922663.22
922664.19
922664.44
922665.06
922665.39
922664.69
922663.86
922664.63
922657.79
922678.18
Easting
(m)
192217.25
192216.80
192216.25
192216.36
192216.75
192217.25
192217.51
192181.05
192181.51
192181.96
192181.66
192182.45
192202.03
192202.61
192202.52
192195.10
192194.42
192194.26
192194.73
192194.64
192195.26
192187.02
192177.19
192218.06
192174.88
192152.56
192151.60
192164.94
192170.15
192153.67
192170.62
192144.93
192157.75
192247.32
192247.32
192246.75
192247.63
192247.80
192247.37
192247.01
192247.55
192248.22
192182.74
192192.86
Top of Screen
(ft MSL)
190.6
195.7
201.0
206.2
210.9
200.6
216.5
197.1
202.6
207.6
212.9
216.8
207.5
211.3
216.6
200.5
204.7
210.0
214.9
205.1
215.9
221.4
221.4
218.5
220.3
221.2
218.8
215.9
212.4
216.6
215.1
214.5
212.4
215.7
217.6
214.6
209.6
204.5
199.5
209.6
215.7
214.8
215.6
217.1
Bottom of Screen
(ft MSL)
185.6
190.7
196.0
201.2
205.9
195.6
211.5
192.1
197.6
202.6
207.9
211.8
202.5
206.3
211.6
195.5
199.7
205.0
209.9
200.1
195.9
196.4
216.4
213.5
215.3
216.2
213.8
210.9
207.4
211.6
210.1
209.5
207.4
195.7
212.6
209.6
204.6
199.5
194.5
204.6
195.7
209.8
215.1
216.6
Final Report
30 September 2008
EPA/ORD
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141
Table B.2. Cove piezometer locations and screened intervals. Depths are reported relative to the
sediment/water interface at the bottom of the pond.
Piezometer
PZ1
PZ2
PZ3
PZ4
PZ5
PZ6
PZ7
PZ8
PZ9
PZ10
PZ11
PZ12
Northing
(m)
922667.24
922678.65
922680.04
922697.20
922680.08
922667.76
922677.60
922703.75
922722.63
922762.65
922838.42
922675.88
Easting
(m)
192201.46
192208.97
192203.74
192211.42
192224.25
192220.32
192248.06
192228.62
192234.24
192237.91
192255.49
192298.64
Top of Screen
(ft below interface)
4.5
4.5
4.0
4.5
4.5
6.5
6.5
5.8
5.6
5.3
4.5
3.0
Bottom of Screen
(ft below interface)
5.0
5.0
4.5
5.0
5.0
7.0
7.0
6.3
6.1
5.8
5.0
3.5
Final Report
30 September 2008
EPA/ORD
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142
Table B.3. Approximate locations where advective flux meter was deployed at the water/sediment interface.
Location
SM1A
SM2A
SM2B
SM1B
Northing (m)
922,678.155
922,671.907
922,681.992
922,680.950
Easting (m)
192,209.740
192,209.880
192,223.798
192,224.623
Note: Locations were surveyed using a Trimble hand-held GPS unit and are considered accurate to approximately
20ft.
Final Report
30 September 2008
EPA/ORD
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143
APPENDIX C
POTENTIOMETRIC SURFACE DATA
Final Report 30 September 2008 EPA/ORD
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144
Table C.I. Data Used for Preparation of Potentiometric Surface for April 26,2007.
Well
RSK1
RSK7
RSK8
RSK12
RSK13
RSK15
RSK16
RSK19
RSK24
RSK25
RSK26
RSK27
RSK28
RSK29
RSK30
RSK33
RSK34
RSK35
RSK37
RSK41
RSK49
STAFF 1
N1.P3
N2,P2
N3,P2
SHL-11
SHL-19
SHL-21
SHP-01-36X
SHP-01-37X
SHP-01-38A
SHP-05-43
SHP-05-44
Groundwater
Elevation
(ftAMSL)
217.76
217.65
218.58
218.59
218.57
218.56
218.01
217.97
219.97
219.62
219.03
219.15
218.89
218.67
218.49
218.35
218.50
218.39
217.76
217.81
218.32
217.46
217.64
217.60
217.64
218.34
219.80
216.55
217.65
217.42
218.02
217.90
217.81
Final Report
30 September 2008
EPA/ORD
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145
Table C.2. Data Used for Preparation of Potentiometric Surface for September 10,2007.
Well
RSK7
RSK12
RSK15
RSK19
RSK23
RSK24
RSK25
RSK26
RSK27
RSK28
RSK29
RSK30
RSK33
RSK34
RSK35
RSK37
RSK48
RSK49
STAFF 1
N2, P2
N3, P2
SHL-11
SHL-19
SHP-01-37X
SHP-01-38A
SHP-05-44
Groundwater
Elevation
(ftAMSL)
217.24
217.77
217.63
217.42
217.77
218.42
217.95
218.02
218.22
218.06
217.84
217.66
217.21
217.09
216.75
217.26
217.43
217.46
217.19
217.18
217.24
217.59
217.92
216.94
217.44
216.53
Final Report
30 September 2008
EPA/ORD
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146
Table C.3. Data Used for Preparation of Potentiometric Surface for November 7,2007.
Well
RSK7
RSK12
RSK15
RSK19
RSK23
RSK25
RSK26
RSK27
RSK28
RSK29
RSK30
RSK32
RSK33
RSK34
RSK35
RSK37
RSK48
RSK49
STAFF 1
N-1 , P-3
N-2, P-2
N-3, P-2
SHL-11
SHL-19
SHP-01-36X
SHP-01-37X
SHP-05-43
SHP-05-44
Northing (m)
217.95
218.34
218.27
218.05
218.34
218.61
218.59
218.62
218.44
218.35
218.20
218.29
217.80
217.58
217.40
217.99
218.10
218.20
217.93
217.65
217.90
217.96
218.09
218.58
217.80
217.73
216.62
217.21
Final Report
30 September 2008
EPA/ORD
-------
147
APPENDIX D
GEOLOGIC LOGS FOR EXISTING WELLS ADJACENT TO RED COVE
Final Report 30 September 2008 EPA/ORD
-------
148
N2 WELL CLUSTER
(Located Approximately 50 ft from Well Cluster RSK1-7)
Stone & Webster
Engineering Corporation
BORING LOG
Boring sj-2.
J.O. 0^=50Q,!
Sheet 1 of 2
Sit*: SrigPt-eVs 4'"- LAN
Mieat: toe -Kiฃ0
Coordinates:
Groundwtter Depth: H-"* .fT
Contractor:
Logged by: R &>u-
Date Start - Finish:? I'Sl -'
Ground Elevation: ft
Depth so Bedrock: *4!. 5>T Total Depth Drilled: 45.a ft
Driller: \/eXKloii Rig Type: Mo?'Lฃ S-SI
Methods:
DriUiag Soil: 1^"
Drilling Rock: KXJ
Casing Used:
fa ? ncjiiSR tif A>-o 4"cA>i>JZ>. To "41.^5
J, 5PT
Comments:
(S)
(ft)
yptlNo
Blow i
Of
^Recovery
RQD
use
Symbol
Sample Description
(fe")
/ ct-ie. i> -)
/ FLoo7=> , (Tbp 2 )
NouT?L*,-iT>c f"JE5j
joT. 'A') ^-Sl'i/i CO
(04,
5P
YRu./i
Lฐ PP'-
Legend/Notes
Dswm is
' ^indicates groimdwater level.
| indicates location of samples.
Blows = number of Wows required 10 drive 2" O.D. sample spoon
6" or distance shows usiag 140 pouad hammer falling 30".
{ ) ซ inches of sample recover/.
Recovery = % rock core recovery.
RQD = Rock Quality Designation.
SFT N = Standard Penetration Test resistance to driving, blows/ft.
USC = Unified Soil Classification system.
* indicates use of 3K) pouad hammer.
Sample Type:
Approved
Date
FIGURE 4-2
BORING LOG
Final Report
30 September 2008
EPA/ORD
-------
149
Stone & Webster Borinง ^
Engineer!!* Corporation BORING LOG ^ 0^000.03
Sin: Logged by: )?. 6,u.e-ป7'E
Biv
(ft)
-
-
atpih
2.0-
30-
40-
.
S.mp^
rซซ
s
5
-s
s
c
No.
4
7
g
'
Blawi
or
Recovery
RQD
10-7-6
Clo-1
V"i
<4o^
srr
N
V
i
u
to
15
13
use
Symbol
5P
j
SH
SP
SM
Sample Description
"zAMP vjUiFsft^^piMfe. * T, % Mo J rcA-S.TtC- fiWE1^
Cci^pti-T ^AT'JI^TEP^ i_T.<&R*V. -2'S ^^/^ _
,.ซ ^ ^. -*ซป. =x.ftLorF.ซ,|
1 " 1 | X/c^l -
C-ilT" ^ i-ns/ Pi i<;TV Ciป^Pi>CT SlfunATEP T"A<^
;>tl i *3LtCf*PU7 rl-*^s> 1 Jt- , ^ **r r w ' - ^
^&N|{ฃ s^^^ V-T ^fi^V0^^1^
TOP of RacK, t AIS Ft
-v< Oe-ifJ Q-ซ.T?. AT OOTIO- ( ^.wTiffi. uwoi-u^-e'is-
EMD oP 9oซ.ii-rif- ft Ab FT.
Note: See Sheet 1 for Boring Summary tad Ltgeod Inforaialiaa PProv tปte
FIGURE 4-2 cont.
BORING LOG
Final Report
30 September 2008
EPA/ORD
-------
150
N3 WELL CLUSTER
(Located Approximately 50 ft from Well Cluster RSK36-43)
Stone & Webster
Engineering Corporation
BORING LOG
Boring M-"3
j.o. 06000.03
Shea I of 2
Sins: ป
Coordinates:
Gtoundwiter Depth:
Contractor: Reov^
Depth to Bedrock: 14.o
Driller V/E.HUOIJ
Logged by: K -
Date Sun Finish: I I I !
Ground Elevation: ft
Total Depth Drilled: IT ft
Rig Type: g,-S3>
Methods:
Drilling Soil:
Ssmpluig Soil:
Drilling Roclc:
Casing Used: 2~i rr OF- H *
Depth
RQD
Sample Description
52.
5-4-7
rr)
7-10-15
13-
To
Lซgtnd/Notes
4 Datum is
^ฃ indicates groundwater level.
| indicates location of samples.
Blows = number of blows required to drive 2" O,D. sample spoon
6* or distsnce shown using 140 pousd bammer falling 30".
( ) inches of saznple recovery,
Recovery = % roek care recovery.
RQD = Rock Quality Desigoation.
SPT N = Standard Penetration Test resistance to driving, blows/ft.
USC = Unified Soil Classification system.
* indicates use of 300 pound hammer.
Sample Type:
Approved
Date
FIGURE 4-2
BORING tOG
Final Report
30 September 2008
EPA/ORD
-------
Stone & Webster
Engineering Corporation
151
BORING LOG
Boring 10 - "i
Slices 2 of 2.
Site:
Logged by: ฃ f> g,
depth
Type
Recovery
RQD
Sample Description
2o-
25-
35-
43-
a-)
1-5-11
Ib
sP
fS
"TO
of- R-OiJC
14=. 5 frT.
ซ4 cs^s JT-. ซi-
ITAIZ- vER_Ti-Lป.i-.
fHAe.TuB.SPj
. AT kA-'oD, t>l
t P Mot* , IA
17.o FT.
NoU: See Sheet 1 for Boring Summary and Legend Information
Approved
Date
FIGURE 4-2 cont.
BORING LOG
Final Report
30 September 2008
EPA/ORD
-------
152
BORING SEA-4
(Located Approximately 10 ft from Well Cluster RSK13-15)
Itf I
09^flh Project : Barson's Construction Boring Log
m^SnO Landfill Ctosur. , No_ SฃA.4
I A ConauKent* no. Ft. U8Vซns B.I uo 195 8511
Contractor: Sal flpBFlton top. Otta: 8 Feb. -10 Fao. M
InglneoirSeeJoglet : J-JinmiB
taring Ueathui : Sw Stt Ran .
Ground Surface Eltซ. : 228,00 W.l.r Lซ~l :
Depth
((I)
0.5
1 1.8
2
2.1
3ซ
4 4.5
9.9
6,.s
7,S
8,s
9,S
1ฐ,,S
11 ซ
12,^
13,o
14,4,
15,s,
16ซ
17,7,
18,,s
19
IS 5
20
Sซmplป
No.
S-l
S-2
S-3
S-4
S-5
Granular So^i
Kawi/ft.
0-t
ซป
10-30
30-50
>M
Dert&ity
VXoou
LOOM
M. Derwa
Dense
V. Oenu
Pan (In)
/Hac.
ie.8
iaM
Density
V. Soil
Soil
bl. 5&rt
Siiff
V. Sbn
Hard
Blowa;ซ-
a
s
a
4
5
4
S
3
S
G
6
6
1.1 Data: 10 f*
Sซmplซ
Description
FBJ^ Fma e maditim SAND, race
10 SrBe coatM wnd and fine 10
roo
BrrMft, One lo matfum SAND, ttttga
coatee sand and fine amvei
Srown. fine to coarM SAND
Brown, rtne 13 coarte SAND, Erace
Ane^aval
Brown, (ne SAN0, ซttfe ซ> ioma
madlym to coarie cand and fine
gmปel
Caalng SI;. : 3-V4* 1.0. Hoin Slam
Sampler : I -If Sp',1 Swor, I NX
Cora Banal
n Caalog at : 0
Remarfce
(1)
temarka:
ฃ1J S-1 Iwm iwgaf.
(2) All conng Vmea in rrjrwlei
Stratum
Description
FLU Fine D meSvm SAND, race
to ^EOa coa/se sand and rina &
coane gravai, race silt ซnth
oecmaionai roots {SP)
0.01
Fine lo medium SAND, IsSie coarse
aand and line gravel fSPrSW;
(7-51...
F:ne % coarie SAMD fSW)
- Trace rirva graved below 1 4-
(17.51
Bna SAND, 1 me to some cav/ifi
aand and fine gravel [SP^SWi
Boring Log
Boring No. SEA ซ
Rel. No. 3924S log is ft compjltcion of wjbsuHact con^boni end toil or tvฃk das^rtcaEipni Q&minxl Irom tfM ftalti waif Mborcloiy testing ol
umpltL Stmtt hcv* b**n irvtarprdad by commonly accapwf procedural. Tha tlracum linaf may be tranutiormr and a^mnrmle. Water lave<
tnatiuramantt have been made in VM open borehole* at fit time and location intfeated. and may wry wnrft tma. geologic contiiton w comtfuctton tciiviry
recycled papei
A-li
Final Report
30 September 2008
EPA/ORD
-------
153
Pap I of 2
gnfdfffc Projtct : Barson's Construction BOfinQ L.OQ '
aiSna UndlillClMiir. rtniMo.MM
SEA Cenaultanta no. Ft. DevenS n.f No 392.151 1
Englnaara/Arehltaela
cer.lr.dor: So! EifHoavcn Corp Oala: If*. tOFat>.66 Caaing sin : 3-W 1.0. Holl* Sปm
f flgtiMarXteotogM : J. JaWMlo Simple : MS' SpSt Spoon S NX
Borin, UMlbm : SaaSปPtt>l Cw Bum
Oround Surfac. Elm. : 22ซ 00 Watar Laval : I J Pala : '0 Fa= W Coring X : 0
D.plh
(f()
KJ.5
21w
22
22!
23
23.1
24
24!
25
25!
26
29.5
27
27.8
28
28 S
29
295
30
90.!
31
31.S
32
32.!
33
33.5
34
34 .S
35
3!S
36
ie.5
37
3T.S
38
31.5
39
3S.S
40
Sarnpl*
No.
S-6
C-1
Gmrular Sail
Bfevrfc^t
O-l
4-10
10-30
30-50
>5ฎ
Danury
V.lnou
Loosa
M.Oarw
Oania
V. D*riM
Pซn 0n)
/Rซe.
SiVSO
Racovary
Daplh
CD
24-24.J
24.2-292
ป 100%
CohMMa SoiU
Blowi'Fl.
<2
2-4
4-1
8-15
1S-30
>30
Danttly
V. Soft
Sol!
M. SIP
Still
V. Soft
Hart}
Bloปa/8"
i&2"-
60/0"
CCHINQ
11
t
B
7
I
Simpl*
0**crlpllon
Gray, SILT and fina SANO. nea
madKim to eoarปa sand and gravaE
{glacial II)
Fraah U iHgrllly acad. bioM
GFUNOOIOHfTE wax cloiary a
madium apacad. BoM p^rtar |otnu:
Maply dioprng (70- 10 90T. Kima
baalad
Bottom o! Expfombon at 29.7
Ramarfca
(2)
lamarka:
(1) S-1 ftom augaf.
(2) M coring tirmi Inmlftjlat
Stratum
Description
Rna SAND. liOa o uma coana
aand and fina graval (SP/SWJ
(22.51
Sit and faa SArJO, net madiuo
lo coarta Mnd and gravat (SM>
(24.21
Vary hard to hard, dark gray.
aqutgmni^ar txoeta
GRANOOICflrrE
i29.2)
Boring Log
Bonng No. SEA-4
Rป! No. 39285-1
Enterrm&on on mซi log it * eorrp^ltion or tubsurtec* candittom vป3 Kti! Of rock tiMtt&4Bant obiimad Irctm Biซ **rj ซt wdi at laborttory Ittlmo. at
unipt**. Stntt hlv* bun tnUfprปl*d by eommonV KCtpud procซOV*ซ. Thซ itnilum ^ซi mซy b* trtntilionAj ind ppeoxim*!*- Wซur Seval
mMSUT*mซnM hซwซ b**^ mซdซ in tft* opซn bor*^cM*t tE !hซ Dm* *rd location ind^calwi. and may vary mm tim*. geoSoojc condtfion or eoniEructorv activity.
P2 >tra blowi
A-20
Final Report
30 September 2008
EPA/ORD
-------
154
APPENDIX E
Summary of field chemistry data for groundwater sampled from RSK wells within Red
Cove Study Area adjacent to Shepley's Hill Landfill
Final Report 30 September 2008 EPA/ORD
-------
155
Table E.1. Summary of field geochemical data collected during ground-water sampling on March 13-14, 2006 adjacent to Shepley's Hill Landfill.
The following abbreviations are used within the table: ft btoc = feet below top of casing, COND = specific conductance, ORP = oxidation-reduction
potential (measured with platinum electrode), DO = dissolved oxygen, Alk = alkalinity, TIC = total inorganic carbon, NM = not measured, NS = not
sampled.
Location
RSK1
RSK2
RSK3
RSK4
RSK5
RSK6
RSK7
RSK8
RSK9
RSK10
RSK11
RSK12
RSK13
RSK14
RSK15
RSK16
RSK17
RSK18
RSK19
RSK20
RSK37
RSK38
RSK39
RSK40
RSK41
RSK42
Date
NS
NS
NS
NS
NS
NS
NS
3/14/2006
3/14/2006
3/14/2006
3/13/2006
3/14/2006
NS
NS
NS
3/14/2006
3/14/2006
3/14/2006
3/14/2006
3/14/2006
NS
NS
NS
NS
NS
NS
Depth to
Water
Table
ft btoc
~
~
~
~
~
~
~
9.72
9.2
9.1
9.48
9.14
~
~
~
1.78
2.1
1.95
2.05
2.2
~
~
~
~
~
~
Temp.
"C
~
~
~
~
~
~
~
11.6
9.2
9.1
9.4
12.5
~
~
~
10.9
11.2
8.1
7
8.6
~
~
~
~
~
~
COND
u,S/cm
~
~
~
~
~
~
~
534
584
613
608
534
~
~
~
469
462
519
604
471
~
~
~
~
~
~
PH
~
~
~
~
~
~
~
6.97
6.79
6.56
6.53
6.35
~
~
~
6.79
6.92
6.73
6.73
6.88
~
~
~
~
~
~
ORP
mV
~
~
~
~
~
~
~
38.6
-108.2
-83.9
15.0
-46.6
~
~
~
-123.0
-93.8
-115.0
-105.0
-119.0
~
~
~
~
~
~
DO
(electrode)
mg/L
~
~
~
~
~
~
~
NM
NM
NM
NM
NM
~
~
~
NM
NM
NM
NM
NM
~
~
~
~
~
~
DO
(Chemet)
mg/L
~
~
~
~
~
~
~
1-2
1-2
1
4
4-5
~
~
~
1-2
2-3
1
1
3-4
~
~
~
~
~
~
Turbidity
NTU
7.46
1.00
1.38
0.95
2.03
2.78
3.10
7.21
NM
4.07
~
Ferrous
Iron
mg/L
~
~
~
~
~
~
~
NM
NM
NM
NM
NM
~
~
~
NM
NM
NM
NM
NM
~
~
~
~
~
~
Alk
(mg/L
CaCO3)
~
~
~
~
~
~
~
NM
NM
NM
NM
NM
~
~
~
NM
NM
NM
NM
NM
~
~
~
~
~
~
TIC
mg/LC
~
~
~
~
~
~
~
47.6
51.9
57.9
51.7
73.9
~
~
~
39.7
40.3
39.6
61
43.9
~
~
~
~
~
~
Final Report
30 September 2008
EPA/ORD
-------
156
Table E.2. Summary of field geochemical data collected during ground-water sampling on May 15-18, 2006 adjacent to Shepley's Hill Landfill.
The following abbreviations are used within the table: ft btoc = feet below top of casing, COND = specific conductance, ORP = oxidation-reduction
potential (measured with platinum electrode), DO = dissolved oxygen, Alk = alkalinity, TIC = total inorganic carbon, NM = not measured, NS = not
sampled.
Location
RSK1
RSK2
RSK3
RSK4
RSK5
RSK6
RSK7
RSK8
RSK9
RSK10
RSK11
RSK12
RSK13
RSK14
RSK15
RSK16
RSK17
RSK18
RSK19
RSK20
RSK37
RSK38
RSK39
RSK40
RSK41
RSK42
Date
NS
NS
NS
NS
NS
NS
NS
NS
5/18/2006
NS
NS
NS
5/18/2006
5/18/2006
5/18/2006
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
Depth
to
Water
Table
ft btoc
~
~
~
~
~
~
~
~
8.40
~
8.64
~
7.21
7.02
7.21
~
~
~
~
~
~
~
~
~
~
~
Temp.
"C
~
~
~
~
~
~
~
~
15.58
~
~
~
13.92
12.07
13.85
~
~
~
~
~
~
~
~
~
~
~
COND
u,S/cm
~
~
~
~
~
~
~
~
591
~
~
~
281
363
349
~
~
~
~
~
~
~
~
~
~
~
PH
~
~
~
~
~
~
~
~
6.57
~
~
~
6.59
6.51
6.36
~
~
~
~
~
~
~
~
~
~
~
ORP
mV
~
~
~
~
~
~
~
~
-109.3
~
~
~
-85.2
-80.6
-47.0
~
~
~
~
~
~
~
~
~
~
~
DO
(electrode)
mg/L
~
~
~
~
~
~
~
~
0.35
~
~
~
0.30
0.40
0.29
~
~
~
~
~
~
~
~
~
~
~
DO
(Chemet)
mg/L
<0.1
~
~
~
<0.1
<0.1
<0.1
~
~
~
~
~
~
~
~
~
~
~
Turbidity
NTU
~
~
~
~
~
~
~
~
8.90
~
~
~
1.70
1.14
2.77
~
~
~
~
~
~
~
~
~
~
~
Ferrous
Iron
mg/L
~
~
~
~
~
~
~
~
NM
~
~
~
NM
NM
NM
~
~
~
~
~
~
~
~
~
~
~
Alk
(mg/L
CaCO3)
~
~
~
~
~
~
~
~
257.4
~
~
~
119.6
154.2
152.2
~
~
~
~
~
~
~
~
~
~
~
TIC
mg/LC
~
~
~
~
~
~
~
~
71.4
~
~
~
31.6
40.6
48.5
~
~
~
~
~
~
~
~
~
~
~
Final Report
30 September 2008
EPA/ORD
-------
157
Table E.3. Summary of field geochemical data collected during ground-water sampling on August 8-10, 2006 adjacent to Shepley's Hill Landfill.
The following abbreviations are used within the table: ft btoc = feet below top of casing, COND = specific conductance, ORP = oxidation-reduction
potential (measured with platinum electrode), DO = dissolved oxygen, Alk = alkalinity, TIC = total inorganic carbon, NM = not measured, NS = not
sampled.
Location
RSK1
RSK2
RSK3
RSK4
RSK5
RSK6
RSK7
RSK8
RSK9
RSK10
RSK11
RSK12
RSK13
RSK14
RSK15
RSK16
RSK17
RSK18
RSK19
RSK20
RSK37
RSK38
RSK39
RSK40
RSK41
RSK42
Date
8/10/2006
8/8/2006
8/10/2006
8/10/2006
8/10/2006
8/8/2006
8/10/2006
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
Depth to
Water
Table
ft btoc
6.18
6.10
6.60
6.18
6.42
6.00
6.10
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
Temp.
"C
15.4
15.7
14.3
15.2
14.4
16.6
14.2
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
COND
u,S/cm
628
604
546
627
545
628
541
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
PH
6.75
6.76
6.64
6.84
6.68
6.69
6.45
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
ORP
mV
-98.6
-109.6
-107.3
-108.0
-108.4
-118.3
-88.8
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
DO
(electrode)
mg/L
NM
NM
NM
NM
NM
NM
NM
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
DO
(HACH)
mg/L
0.35
0.34
0.24
0.32
0.31
0.44
0.27
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
Turbidity
NTU
2.62
8.00
1.23
1.25
0.43
5.65
1.34
~
Ferrous
Iron
mg/L
21.5
26.75
21.75
22.75
22.75
18.25
42.00
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
Alk
(mg/L
CaCO3)
282
268
179
269
263
261.4
264
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
TIC
mg/LC
58.6
64.2
56.0
57.8
59.0
60.4
43.8
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
Final Report
30 September 2008
EPA/ORD
-------
158
Table E.4. Summary of field geochemical data collected during ground-water sampling on April 23-27, 2007 adjacent to Shepley's Hill Landfill.
The following abbreviations are used within the table: ft btoc = feet below top of casing, COND = specific conductance, ORP = oxidation-reduction
potential (measured with platinum electrode), DO = dissolved oxygen, Alk = alkalinity, TIC = total inorganic carbon, NM = not measured, NS = not
sampled.
Location
RSK1
RSK2
RSK3
RSK4
RSK5
RSK6
RSK7
RSK8
RSK9
RSK10
RSK11
RSK12
RSK13
RSK14
RSK15
RSK16
RSK17
RSK18
RSK19
RSK20
RSK37
RSK38
RSK39
RSK40
RSK41
RSK42
Date
NS
NS
NS
NS
NS
NS
NS
4/25/2007
4/25/2007
4/25/2007
4/25/2007
4/25/2007
NS
NS
NS
4/24/2007
4/24/2007
4/24/2007
4/24/2007
4/24/2007
NS
NS
NS
NS
NS
NS
Depth to
Water
Table
ft btoc
~
~
~
~
~
~
~
9.48
8.94
8.87
9.21
8.88
~
~
~
1.49
1.75
1.70
1.75
1.97
~
~
~
~
~
~
Temp.
"C
~
~
~
~
~
~
~
11.7
12.3
11.4
12.0
10.3
~
~
~
14.4
15.6
13.6
14.1
12.3
~
~
~
~
~
~
COND
u,S/cm
~
~
~
~
~
~
~
626
607
716
382
311
~
~
~
467
467
548
638
480
~
~
~
~
~
~
PH
~
~
~
~
~
~
~
6.72
6.63
6.37
6.47
6.41
~
~
~
6.77
6.66
6.43
6.41
6.47
~
~
~
~
~
~
ORP
mV
~
~
~
~
~
~
~
-110.4
-113.1
-96.4
-108.0
-108.0
~
~
~
-123.4
-156.3
-111.6
-93.3
-116.2
~
~
~
~
~
~
DO
(electrode)
mg/L
~
~
~
~
~
~
~
NM
NM
NM
NM
NM
~
~
~
NM
NM
NM
NM
NM
~
~
~
~
~
~
DO
(HACH)
mg/L
~
~
~
~
~
~
~
0.00
0.00
0.45
0.44
0.37
~
~
~
0.01
0.12
0.30
0.22
0.33
~
~
~
~
~
~
Turbidity
NTU
0.94
0.42
0.55
0.34
0.43
1.82
0.35
0.57
1.36
0.64
~
Ferrous
Iron
mg/L
~
~
~
~
~
~
~
NM
NM
NM
NM
NM
~
~
~
NM
NM
NM
NM
NM
~
~
~
~
~
~
Alk
(mg/L
CaCO3)
~
~
~
~
~
~
~
272
279
355
82
161
~
~
~
164
194
258
299
214
~
~
~
~
~
~
TIC
mg/LC
~
~
~
~
~
~
~
67.5
66.6
89.1
41.3
32.3
~
~
~
62.7
38.1
55.1
62.0
48.3
~
~
~
~
~
~
Final Report
30 September 2008
EPA/ORD
-------
159
Table E.5. Summary of field geochemical data collected during ground-water sampling on August 20-23, 2007 adjacent to Shepley's Hill Landfill.
The following abbreviations are used within the table: ft btoc = feet below top of casing, COND = specific conductance, ORP = oxidation-reduction
potential (measured with platinum electrode), DO = dissolved oxygen, Alk = alkalinity, TIC = total inorganic carbon, NM = not measured, NS = not
sampled.
Location
RSK1
RSK2
RSK3
RSK4
RSK5
RSK6
RSK7
RSK8
RSK9
RSK10
RSK11
RSK12
RSK13
RSK14
RSK15
RSK16
RSK17
RSK18
RSK19
RSK20
RSK37
RSK38
RSK39
RSK40
RSK41
RSK42
Date
8/21/2007
NS
8/21/2007
8/21/2007
8/21/2007
8/21/2007
8/21/2007
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
8/22/2007
8/22/2007
8/22/2007
8/22/2007
8/22/2007
8/22/2007
Depth to
Water
Table
ft btoc
6.37
~
6.76
6.96
6.60
6.29
6.10
~
~
~
~
~
~
~
~
~
~
~
~
~
4.38
4.36
4.17
4.22
4.19
4.40
Temp.
"C
13.7
~
16.9
14.3
13.5
15.6
14.2
~
~
~
~
~
~
~
~
~
~
~
~
~
13.6
13.9
17.1
16.3
15.2
15.5
COND
u,S/cm
514
~
499
531
459
557
541
~
~
~
~
~
~
~
~
~
~
~
~
~
312
294
184
152
45
212
PH
6.40
~
6.48
6.85
6.62
6.81
6.45
~
~
~
~
~
~
~
~
~
~
~
~
~
6.09
6.14
6.44
6.31
6.24
6.17
ORP
mV
NM
~
NM
NM
NM
NM
NM
~
~
~
~
~
~
~
~
~
~
~
~
~
NM
NM
NM
NM
NM
NM
DO
(electrode)
mg/L
NM
~
NM
NM
NM
NM
NM
~
~
~
~
~
~
~
~
~
~
~
~
~
NM
NM
NM
NM
NM
NM
DO
(HACH)
mg/L
0.37
~
0.78
1.04
0.45
1.02
0.39
~
~
~
~
~
~
~
~
~
~
~
~
~
2.50
0.60
0.76
0.47
1.30
0.68
Turbidity
NTU
0.88
1.17
0.75
0.58
0.88
2.53
13.6
0.81
2.47
3.18
6.89
3.40
Ferrous
Iron
mg/L
10.5
~
18.25
19.25
24.5
19.0
32.0
~
~
~
~
~
~
~
~
~
~
~
~
~
0.0
6.5
7.75
21.0
17.75
15.25
Alk
(mg/L
CaCO3)
216
~
189
196
195
213
220
~
~
~
~
~
~
~
~
~
~
~
~
~
15
57
94
150
152
84
TIC
mg/LC
55.3
~
46.8
53.8
49.0
57.6
63.3
~
~
~
~
~
~
~
~
~
~
~
~
~
7.0
24.8
31.2
42.8
43.5
27.9
Final Report
30 September 2008
EPA/ORD
-------
160
Table E.6. Summary of field geochemical data collected during ground-water sampling on September 11-13 and October 30, 2007 adjacent to
Shepley's Hill Landfill; October 30 sampling conducted by EPA Region 1 Laboratory. The following abbreviations are used within the table: ft btoc
= feet below top of casing, COND = specific conductance, ORP = oxidation-reduction potential (measured with platinum electrode), DO =
dissolved oxygen, Alk = alkalinity, TIC = total inorganic carbon, NM = not measured, NS = not sampled.
Location
RSK1
RSK2
RSK3
RSK4
RSK5
RSK6
RSK7
RSK8
RSK9
RSK10
RSK11
RSK12
RSK13
RSK14
RSK15
RSK16
RSK17
RSK18
RSK19
RSK20
RSK37
RSK38
RSK39
RSK40
RSK41
RSK42
Date
NS
NS
NS
NS
10/30/2007
NS
NS
NS
9/11/2007
9/12/2007
9/11/2007
10/30/2007
9/11/2007
9/11/2007
9/12/2007
9/12/2007
9/12/2007
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
Depth to
Water
Table
ft btoc
~
~
~
~
NM
~
~
~
10.29
9.74
9.68
NM
10.05
9.71
8.57
8.48
8.73
~
~
~
~
~
~
~
~
~
~
~
Temp.
"C
~
~
~
~
11.31
~
~
~
15.2
15.4
15.2
12.89
14.7
16.1
17.7
18.2
16.7
~
~
~
~
~
~
~
~
~
~
~
COND
u,S/cm
~
~
~
~
502
~
~
~
605
691
838
753
791
714
346
356
283
~
~
~
~
~
~
~
~
~
~
~
PH
~
~
~
~
6-7
~
~
~
6.73
6.55
6.32
6.18
6.27
6.45
6.59
6.29
5.87
~
~
~
~
~
~
~
~
~
~
~
ORP
mV
~
~
~
~
1.9
~
~
~
-124.2
-100.2
-95.7
-94.9
-110.5
-82.3
-74.0
-53.8
43.8
~
~
~
~
~
~
~
~
~
~
~
DO
(electrode)
mg/L
~
~
~
~
0.09
~
~
~
~
~
~
0.19
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
DO
(HACH)
mg/L
~
NM
~
~
~
0.14
0.59
0.10
NM
0.00
0.59
0.79
0.16
0.02
~
~
~
~
~
~
~
~
~
~
~
Turbidity
NTU
~
~
~
~
0.37
~
~
~
2.59
2.04
2.79
0.44
1.51
3.64
0.69
1.88
1.06
~
~
~
~
~
~
~
~
~
~
~
Ferrous
Iron
mg/L
~
~
~
~
NM
~
~
~
27.00
36.75
32.25
NM
36.25
49.00
12.75
12.25
10.75
~
~
~
~
~
~
~
~
~
~
~
Alk
(mg/L
CaCO3)
~
~
~
~
210
~
~
~
487
300
358
330
331
309
155
154
108
~
~
~
~
~
~
~
~
~
~
~
TIC
mg/LC
~
~
~
~
NM
~
~
~
67.4
88.5
110.0
NM
102.0
102.0
41.1
52.9
60.9
~
~
~
~
~
~
~
~
~
~
~
Final Report
30 September 2008
EPA/ORD
-------
161
APPENDIX F
Summary of field chemistry data for groundwater sampled from RCTW wells within Red
Cove Study Area adjacent to Shepley's Hill Landfill.
Final Report 30 September 2008 EPA/ORD
-------
162
Table F.1. Summary of field geochemical data collected from RCTW wells underneath Red Cove adjacent to Shepley's Hill Landfill. The following
abbreviations are used within the table: ft bswi = feet below sediment-water interface, COND = specific conductance, ORP = oxidation-reduction
potential (measured with platinum electrode), DO = dissolved oxygen, Alk = alkalinity, TIC = total inorganic carbon, NM = not measured, NS = not
sampled.
Location
RCTW1
RCTW2
RCTW3
RCTW4
RCTW5
RCTW6
RCTW7
RCTW8
RCTW9
RCTW10
Date
8/8/2006
8/21/2007
8/8/2006
8/21/2007
5/16/2006
8/8/2006
8/21/2007
8/9/2006
8/23/2007
8/9/2006
8/9/2006
8/23/2007
5/17/2006
8/8/2006
8/21/2007
8/9/2006
8/9/2006
4/27/2007
8/9/2006
8/22/2007
Screen
Depth
ft bswi
3.00
1.00
1.50
1.10
1.25
2.10
3.80
1.00
1.25
2.50
Temp.
"C
27.8
16.2
28.0
19.0
12.0
27.5
18.2
21.8
15.9
19.7
22.5
17.2
19.9
26.8
16.8
19.3
26.2
10.9
27.2
20.2
COND
u,S/cm
447
451
446
411
399
438
463
666
569
568
129
279
459
555
474
323
627
663
548
567
PH
6.67
6.64
6.44
6.18
6.56
6.50
6.52
6.36
6.37
6.42
6.82
6.57
6.67
6.72
7.02
6.71
6.69
6.46
6.62
6.50
ORP
mV
-102.4
NM
-69.9
NM
-65.2
-111.5
NM
-88.0
NM
-115.0
-83.7
NM
-143.8
-182.9
NM
-110.0
-116.7
-76.4
-112.0
NM
DO
(electrode)
mg/L
NM
NM
NM
NM
0.33
NM
NM
NM
NM
NM
NM
NM
0.19
NM
NM
NM
NM
NM
NM
NM
DO
(HACH)
mg/L
1.80
NM
2.00
NM
NM
1.70
NM
1.40
NM
0.53
0.80
0.70
NM
0.45
NM
0.29
1.00
0.21
1.50
5.10
Turbidity
NTU
1.20
33.20
0.72
9.30
NM
1.20
3.20
0.71
0.88
1.22
11.80
1.95
NM
4.50
2.02
0.92
16.50
3.33
1.25
2.77
Ferrous
Iron
mg/L
NM
41.75
NM
20.50
NM
NM
27.75
44.50
32.50
46.25
8.75
16.00
NM
15.50
51.00
24.75
39.00
59.25
11.50
14.00
Alk
(mg/L
CaCO3)
160
167
155
148
NM
148
175
316
222
243
55
97
NM
194
168
139
266
298
232
NM
TIC
mg/LC
36.4
41.2
38.6
45.9
NM
32.4
43.6
69.6
58.9
59.8
11.9
24.1
NM
33.2
35.8
26.2
55.0
63.6
54.8
75.3
Final Report
30 September 2008
EPA/ORD
-------
163
APPENDIX G
Summary of field chemistry data for surface water sampled from within Red Cove
adjacent to Shepley's Hill Landfill
Final Report 30 September 2008 EPA/ORD
-------
164
Table G. 1. Summary of field geochemical data collected for surface water in Red Cove adjacent to Shepley's Hill Landfill. The following abbreviations are used
within the table: ft bws = feet below water surface, COND = specific conductance, ORP = oxidation-reduction potential (measured with platinum electrode), DO =
dissolved oxygen, Alk = alkalinity, TIC = total inorganic carbon, NM = not measured, NS = not sampled.
Location
IC1
IC2
MC1
MC2
SW01
SW02A
SW02B
SW03
SW04
SW05
Date
5/17/2006
5/17/2006
4/23/2007
4/23/2007
4/26/2007
8/20/2007
8/20/2007
9/12/2007
9/13/2007
Depth
ft bws
1.64
1.94
1.64
4.18
0.82
1.64
2.05
0.82
1.64
2.46
3.28
3.44
3.61
0.82
1.64
2.46
3.28
0.82
1.23
1.64
2.05
2.46
2.87
3.28
0.82
1.23
1.64
2.05
2.46
2.87
3.28
3.69
0.82
1.23
1.64
2.05
2.46
2.87
0.82
1.23
1.64
2.05
2.46
2.87
Temp.
c
10.51
10.08
10.64
10.79
14.73
14.34
14.47
15.78
15.75
15.23
13.71
13.8
12.67
17.03
16.56
14.28
13.05
18.08
17.02
16.28
15.85
15.45
15.85
16.06
20.86
19.23
17.26
16.62
16.19
15.93
15.92
16.33
21.3
19.1
18.12
17.66
17.55
17.58
17.87
17.31
17.06
16.59
16.42
16.35
COND
|iS/cm
159
144
133
566
173
175
175
185
186
189
331
437
663
181
180
181
443
254
246
247
257
287
599
727
258
254
249
246
254
275
301
416
251
248
246
248
270
434
255
254
258
261
246
265
pH
5.97
5.93
6.10
6.62
6.04
5.87
5.87
6.00
5.98
5.91
5.78
6.02
7.12
6.41
6.4
5.9
6.0
6.25
6.18
5.91
5.78
5.83
6.06
6.89
6.44
6.31
6.15
5.94
5.91
5.85
5.90
7.19
6.94
6.68
6.58
6.54
6.61
6.61
6.65
6.64
6.51
6.46
6.55
6.54
ORP
mV
120.6
133.3
170.6
-96.5
102.2
102.6
102.2
83.1
80.4
77.2
33.9
6.2
-233.6
238.4
215.4
142.0
27.5
396.7
370.5
268.3
63.1
23.2
-41.3
-221 .4
192.5
182.5
126.6
63.6
37.7
22.8
-1.8
-293.5
258.2
149.2
122.8
74.0
-16.7
-168.4
106.6
132.0
86.7
68.3
49
21.1
DO (electrode)
mg/L
5.33
4.70
6.50
0.19
8.48
7.76
8.40
7.85
8.25
8.64
6.73
7.40
1.55
6.18
6.39
6.87
6.13
5.92
6.78
6.39
4.47
2.57
0.54
0.28
7.77
8.07
6.42
6.17
5.60
4.17
3.30
0.30
1.93
1.29
0.66
0.25
0.04
0.01
6.50
5.56
4.52
4.16
3.82
3.43
DO (HACH)
mg/L
NM
NM
6-8
NM
NM
NM
NM
6.90
7.50
NM
NM
NM
NM
5.80
4.60
4.30
5.00
10.10
NM
7.00
NM
1.40
0.90
NM
6.40
NM
7.30
NM
8.40
NM
4.70
NM
6.30
5.10
8.20
5.00
0.70
0.35
14.80
4.70
3.50
4.00
NM
6.00
Turbidity
NTU
NM
NM
NM
NM
NM
NM
NM
3.84
6.68
3.27
NM
NM
NM
NM
1.53
2.35
61.90
8.54
6.78
6.50
11.10
17.30
145.00
NM
9.01
9.43
8.03
7.58
11.90
18.00
33.40
NM
10.20
7.22
5.60
7.21
10.10
26.10
7.41
6.65
4.96
8.02
7.74
13.10
Ferrous Iron
mg/L
NM
NM
NM
NM
NM
NM
NM
0.55
0.65
0.48
5.50
NM
NM
0.02
0.04
0.79
37.5
0.03
NM
0.28
NM
4.50
32.50
NM
0.09
NM
0.09
NM
2.07
NM
9.5
NM
0.00
0.00
0.09
0.56
10.00
19.75
0.07
0.02
0.22
1.12
1.43
2.50
Alk
(mg/L CaCO3)
NM
NM
NM
NM
NM
NM
NM
24.20
NM
23.20
82.60
NM
NM
NM
NM
NM
NM
40
NM
42
NM
72
196
NM
38
NM
40
NM
50
NM
94
NM
36
44
51
39
79
82
54
31
61
44
60
55
TIC
mg/LC
NS
NS
NS
NS
NS
NS
NS
6.95
7.13
6.5
32
NM
NM
NS
NS
NS
NS
11.7
NS
13.2
NS
19.8
61.1
NS
10.8
NS
11.8
NS
16.9
NS
27.5
NS
10.6
NS
11.1
NS
18.8
NS
12.2
NS
13.7
NS
14.8
NS
Final Report
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165
APPENDIX H
Summary of chemistry data for groundwater sampled from RSK wells within Red Cove
Study Area adjacent to Shepley's Hill Landfill.
Final Report 30 September 2008 EPA/ORD
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166
Table H.1. Summary of chemistry data for groundwater samples collected on March 13-14, 2006 adjacent to Shepley's Hill Landfill. The following
abbreviations are used within the table: ND = not detected, NS = not sampled, QL = quantitation limit.
Location
RSK1
RSK2
RSK3
RSK4
RSK5
RSK6
RSK7
RSK8
RSK9
RSK10
RSK11
RSK12
RSK13
RSK14
RSK15
RSK16
RSK17
RSK18
RSK19
RSK20
RSK37
RSK38
RSK39
RSK42
RSK40
RSK41
Date
NS
NS
NS
NS
NS
NS
NS
3/14/2006
3/14/2006
3/14/2006
3/13/2006
3/14/2006
NS
NS
NS
3/14/2006
3/14/2006
3/14/2006
3/14/2006
3/14/2006
NS
NS
NS
NS
NS
NS
MDL
QL
As
mg/L
0.755
0.827
0.710
1.100
0.746
0.807
0.963
0.967
0.478
0.957
0.00002
0.0001
Fe
mg/L
29.6
54.8
57.4
59.6
38.0
22.1
30.0
40.5
58.7
32.4
0.005
0.017
Mn
mg/L
3.50
0.879
1.04
2.31
2.11
2.42
1.20
1.02
1.22
1.42
0.001
0.004
Ca
mg/L
46.9
36.4
39.6
47.7
50.4
40.6
32.4
30.5
40.2
35.1
0.03
0.08
K
mg/L
8.40
11.6
11.9
7.90
7.25
8.73
9.83
11.8
12.3
11.7
0.06
0.18
Mg
mg/L
6.63
5.20
5.18
5.96
6.69
6.91
6.27
6.68
6.20
7.08
0.03
0.08
Na
mg/L
23.1
18.4
18.2
16.7
14.6
21.0
17.8
15.8
17.9
16.1
0.04
0.14
Cl
mg/L
30.3
28.6
25.7
22.0
16.2
26.3
16.2
16.9
19.6
16.9
0.100
1.00
SO4
mg/L
5.68
ND
0.358
0.385
1.74
13.9
10.9
8.64
2.69
8.65
0.100
1.00
NH3-N
mg/L
3.11
6.82
7.11
4.64
3.15
2.22
4.65
7.01
10.2
5.73
0.02
0.10
TOC
mg/L
2.32
3.01
3.54
3.13
4.21
1.50
2.39
3.01
14.20
2.18
0.14
1.00
Final Report
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Table H.2. Summary of chemistry data for groundwater samples collected on May 15-18, 2006 adjacent to Shepley's Hill Landfill. The following abbreviations
are used within the table: ND = not detected, NS = not sampled, QL = quantitation limit.
Location
RSK1
RSK2
RSK3
RSK4
RSK5
RSK6
RSK7
RSK8
RSK9
RSK10
RSK11
RSK12
RSK13
RSK14
RSK15
RSK16
RSK17
RSK18
RSK19
RSK20
RSK37
RSK38
RSK39
RSK42
RSK40
RSK41
Date
NS
NS
NS
NS
NS
NS
NS
NS
5/18/2006
NS
NS
NS
5/18/2006
5/18/2006
5/18/2006
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
MDL
QL
As
mg/L
0.815
0.384
0.367
0.249
0.00002
0.0001
Fe
mg/L
60.6
31.1
38.9
33.5
0.005
0.017
Mn
mg/L
0.804
1.92
2.86
2.88
0.001
0.004
Ca
mg/L
40.4
22.4
29.5
30.1
0.03
0.08
K
mg/L
13.0
3.38
4.17
4.61
0.06
0.18
Mg
mg/L
5.48
3.17
4.17
4.70
0.03
0.08
Na
mg/L
21.0
7.47
9.85
9.81
0.04
0.14
Cl
mg/L
28.1
7.55
11.6
10.0
0.100
1.00
SO4
mg/L
ND
7.64
10.5
10.5
0.100
1.00
NH3-N
mg/L
7.87
1.22
1.42
1.14
0.02
0.10
TOC
mg/L
1.80
1.31
1.46
1.33
0.14
1.00
Final Report
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Table H.3. Summary of chemistry data for groundwater samples collected on August 8-10, 2006 adjacent to Shepley's Hill Landfill. The following abbreviations
are used within the table: ND = not detected, NS = not sampled, MDL = method detection limit, QL = quantitation limit.
Location
RSK1
RSK2
RSK3
RSK4
RSK5
RSK6
RSK7
RSK8
RSK9
RSK10
RSK11
RSK12
RSK13
RSK14
RSK15
RSK16
RSK17
RSK18
RSK19
RSK20
RSK37
RSK38
RSK39
RSK42
RSK40
RSK41
Date
8/10/2006
8/8/2006
8/10/2006
8/10/2006
8/10/2006
8/8/2006
8/10/2006
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
MDL
QL
As
mg/L
0.642
0.814
0.798
0.882
0.995
0.841
0.708
0.00002
0.0001
Fe
mg/L
26.1
28.5
29.1
30.7
34.6
28.3
54.4
0.005
0.017
Mn
mg/L
3.98
3.64
3.4
2.77
2.28
3.23
2.36
0.001
0.004
Ca
mg/L
65.4
64.9
65.1
62.5
60.7
64.7
43.3
0.03
0.08
K
mg/L
9.14
8.31
8.81
8.4
8.42
8.14
9.07
0.06
0.18
Mg
mg/L
9.12
10.1
10.2
9.95
9.47
10.3
6.14
0.03
0.08
Na
mg/L
25.1
24.8
25.3
25.4
25.3
24.7
19.5
0.04
0.14
Cl
mg/L
23.2
23.4
23.6
25.9
26.2
26.1
21.9
0.100
1.00
SO4
mg/L
8.29
7.59
10.6
15.5
14.2
11.2
4.10
0.100
1.00
NH3-N
mg/L
2.87
2.04
2.27
2.22
2.92
1.89
6.67
0.02
0.10
TOC
mg/L
2.43
2.41
2.4
2.08
2.17
2.22
2.71
0.14
1.00
Final Report
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EPA/ORD
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169
Table H.4. Summary of chemistry data for groundwater samples collected on April 23-27, 2007 adjacent to Shepley's Hill Landfill. The following abbreviations
are used within the table: ND = not detected, NS = not sampled, QL = quantitation limit.
Location
RSK1
RSK2
RSK3
RSK4
RSK5
RSK6
RSK7
RSK8
RSK9
RSK10
RSK11
RSK12
RSK13
RSK14
RSK15
RSK16
RSK17
RSK18
RSK19
RSK20
RSK37
RSK38
RSK39
RSK42
RSK40
RSK41
Date
NS
NS
NS
NS
NS
NS
NS
4/25/2007
4/25/2007
4/25/2007
4/25/2007
4/25/2007
NS
NS
NS
4/24/2007
4/24/2007
4/24/2007
4/24/2007
4/24/2007
NS
NS
NS
NS
NS
NS
MDL
QL
As
mg/L
0.860
0.941
0.739
0.941
0.860
0.850
0.876
0.757
0.464
0.848
0.00002
0.0001
Fe
mg/L
48.0
65.5
75.5
43.2
31.9
27.0
40.3
66.1
59.1
50.9
0.005
0.017
Mn
mg/L
4.39
0.92
1.19
1.25
1.23
1.77
1.38
1.42
1.2
1.57
0.001
0.004
Ca
mg/L
56.0
44.2
57.4
28.6
25.1
34.9
27.2
30.0
45.5
29.1
0.03
0.08
K
mg/L
9.8
12.2
13.0
5.9
5.01
8.4
10.1
11.8
11.6
11.2
0.06
0.18
Mg
mg/L
8.25
5.5
6.91
3.94
3.52
5.97
4.54
4.75
6.44
4.91
0.03
0.08
Na
mg/L
24.4
19.2
18.8
11.0
8.28
19.5
14.2
15.6
16.0
14.5
0.04
0.14
Cl
mg/L
35.4
32.5
33.0
7.52
5.39
24.7
20.1
21.5
15.4
20.1
0.100
1.00
SO4
mg/L
3.92
ND
0.37
2.88
1.88
14.0
10.1
3.64
1.17
5.23
0.100
1.00
NH3-N
mg/L
4.39
8.77
9.20
4.18
3.30
3.20
5.87
7.92
10.9
6.96
0.02
0.10
TOC
mg/L
2.30
2.53
3.07
1.38
1.22
2.55
1.78
2.14
2.84
2.00
0.14
1.00
Final Report
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Table H.5. Summary of chemistry data for groundwater samples collected on August 20-23, 2007 adjacent to Shepley's Hill Landfill. The following
abbreviations are used within the table: ND = not detected, NS = not sampled, MDL = method detection limit, QL = quantitation limit.
Location
RSK1
RSK2
RSK3
RSK4
RSK5
RSK6
RSK7
RSK8
RSK9
RSK10
RSK11
RSK12
RSK13
RSK14
RSK15
RSK16
RSK17
RSK18
RSK19
RSK20
RSK37
RSK38
RSK39
RSK42
RSK40
RSK41
Date
8/21/2007
NS
8/21/2007
8/21/2007
8/21/2007
8/21/2007
8/21/2007
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
8/22/2007
8/22/2007
8/22/2007
8/22/2007
8/22/2007
8/22/2007
MDL
QL
As
mg/L
0.509
0.722
0.797
0.816
0.811
0.661
0.003
0.016
0.082
0.177
0.592
0.516
0.00002
0.0001
Fe
mg/L
18.1
21.3
22.6
24.7
22.6
38.8
0.02
4.94
5.93
14.5
45.5
32.9
0.005
0.017
Mn
mg/L
3.08
2.71
2.46
1.99
3.13
2.07
0.01
2.3
7.56
5.0
3.72
4.23
0.001
0.004
Ca
mg/L
57.9
51.2
51.4
45.9
54.0
42.5
5.09
16.5
22.6
18.1
22.4
32.4
0.03
0.08
K
mg/L
6.19
7.67
7.14
7.46
7.55
8.28
1.17
2.77
4.41
3.7
4.02
4.11
0.06
0.18
Mg
mg/L
8.35
7.4
7.91
7.15
8.17
6.12
1.19
2.83
2.92
2.42
3.39
4.18
0.03
0.08
Na
mg/L
24.2
24.2
24.6
23.8
24.8
23.1
0.96
2.93
4.26
3.04
4.29
5.15
0.04
0.14
Cl
mg/L
22.8
23.0
24.4
21.8
26.2
21.2
1.31
2.15
2.62
2.01
2.98
3.88
0.100
1.00
SO4
mg/L
16.0
16.2
14.9
15.9
14.6
10.5
4.19
8.47
8.90
8.91
11.4
11.9
0.100
1.00
NH3-N
mg/L
1.41
2.06
1.59
2.44
1.59
4.83
0.03
0.37
1.83
0.99
1.18
1.01
0.02
0.10
TOC
mg/L
2.40
2.15
1.99
1.76
1.94
2.64
0.67
0.87
0.81
1.09
1.04
1.05
0.14
1.00
Final Report
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EPA/ORD
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171
Table H.6. Summary of chemistry data for groundwater samples collected on September 11-13, 2007 adjacent to Shepley's Hill Landfill; October 30, 2007
sampling and analysis conducted by EPA Region 1 Lab. The following abbreviations are used within the table: ND = not detected, NM = not measured, NS ;
not sampled, MDL = method detection limit, QL = quantitation limit.
Location
RSK1
RSK2
RSK3
RSK4
RSK5
RSK6
RSK7
RSK8
RSK9
RSK10
RSK11
RSK12
RSK13
RSK14
RSK15
RSK16
RSK17
RSK18
RSK19
RSK20
RSK37
RSK38
RSK39
RSK42
RSK40
RSK41
Date
NS
NS
NS
NS
10/30/2007
NS
NS
NS
9/11/2007
9/12/2007
9/11/2007
10/30/2007
9/11/2007
9/11/2007
9/12/2007
9/12/2007
9/12/2007
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
MDL
QL
As
mg/L
0.810
0.84
0.80
0.66
0.670
0.74
0.63
0.42
0.29
0.06
0.00002
0.0001
Fe
mg/L
28.0
45.6
62.3
81.5
80.0
78.2
59.1
34.2
36.5
11.9
0.005
0.017
Mn
mg/L
2.70
3.88
0.80
0.92
0.89
1.87
2.09
2.55
1.92
0.80
0.001
0.004
Ca
mg/L
49.0
55.8
52.1
64.1
58.0
58.0
61.6
27.9
29.7
27.6
0.03
0.08
K
mg/L
9.6
10.4
13.7
14.8
16.0
13.7
13.0
3.59
6.23
7.64
0.06
0.18
Mg
mg/L
7.8
7.80
6.51
7.63
7.3
6.9
7.29
3.99
3.68
4.95
0.03
0.08
Na
mg/L
27
26.1
22.1
21.4
23.0
20.7
20.5
10.5
7.7
8.3
0.04
0.14
Cl
mg/L
25.0
30.8
29.4
32.0
31.0
31.7
31.7
12.0
10.2
12.0
0.100
1.00
SO4
mg/L
13.0
3.93
ND
ND
ND
ND
ND
7.28
5.11
4.57
0.100
1.00
NH3-N
mg/L
NM
4.39
9.41
10.9
NM
10.5
9.75
1.26
1.97
0.34
0.02
0.10
TOC
mg/L
NM
2.40
3.00
3.90
NM
3.57
3.41
1.50
2.43
2.31
0.14
1.00
Final Report
30 September 2008
EPA/ORD
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172
APPENDIX I
Summary of chemistry data for groundwater sampled from RCTW wells within Red Cove
Study Area adjacent to Shepley's Hill Landfill.
Final Report 30 September 2008 EPA/ORD
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173
Table 1.1. Summary of chemistry data for groundwater samples collected from RCTW wells adjacent to Shepley's Hill Landfill. The following
abbreviations are used within the table: ND = not detected, NS = not sampled, MDL = method detection limit, QL = quantitation limit.
Location
RCTW1
RCTW2
RCTW3
RCTW4
RCTW5
RCTW6
RCTW7
RCTW8
RCTW9
RCTW10
Date
8/8/2006
8/21/2007
8/8/2006
8/21/2007
8/8/2006
8/21/2007
8/9/2006
8/23/2007
8/9/2006
8/9/2006
8/23/2007
5/17/2006
8/8/2006
8/21/2007
8/9/2006
8/9/2006
4/27/2007
8/9/2006
8/22/2007
MDL
QL
As
mg/L
0.400
0.530
0.357
0.288
0.368
0.321
0.751
0.622
0.911
0.284
0.167
0.400
0.596
0.542
0.616
1.060
0.723
0.160
0.300
0.00002
0.0001
Fe
mg/L
28.4
31.7
18.8
15.4
26.7
34.1
68.9
48.0
59.1
11.7
17.6
41.8
51.1
47.8
28.4
50.2
57.8
11.4
16.2
0.005
0.017
Mn
mg/L
2.51
1.29
2.09
1.63
0.78
0.84
1.14
0.76
1.45
0.69
0.96
0.77
0.67
0.64
0.91
1.78
1.86
2.70
3.41
0.001
0.004
Ca
mg/L
28.2
30.6
27.0
23.5
28.3
31.3
55.0
39.6
44.3
8.7
22.0
24.7
27.2
24.1
22.5
51.0
53.2
56.2
68.5
0.03
0.08
K
mg/L
9.3
7.1
9.7
10.1
8.4
9.3
13.4
11.8
11.3
2.6
5.8
10.6
10.7
10.2
6.1
12.4
12.1
10.5
11.3
0.06
0.18
Mg
mg/L
4.79
4.67
5.64
5.27
4.83
5.05
7.18
4.83
5.76
1.30
3.33
4.65
5.04
4.10
3.30
7.17
7.46
9.57
10.9
0.03
0.08
Na
mg/L
18.0
22.3
20.9
23.7
17.7
21.6
19.9
23.2
16.8
3.9
14.7
19.5
18.2
18.5
10.7
18.3
18.2
23.0
26.9
0.04
0.14
Cl
mg/L
21.1
26.3
26.2
26.1
21.7
27.7
28.0
29.0
23.5
0.2
26.1
22.8
21.9
23.9
8.56
27.4
27.7
28.9
29.2
0.100
1.00
SO4
mg/L
5.39
4.73
5.03
3.37
8.73
6.20
0.44
ND
0.58
4.83
2.17
12.3
10.0
9.95
2.65
ND
ND
ND
ND
0.100
1.00
NH3-N
mg/L
7.23
4.13
8.19
7.89
5.50
5.17
9.26
7.52
7.31
0.79
1.26
6.75
7.58
6.58
3.68
7.84
7.86
6.30
5.82
0.02
0.10
TOC
mg/L
5.12
4.00
2.64
4.60
2.98
4.10
2.90
2.54
2.75
3.38
2.22
NS
2.06
2.09
2.27
3.57
2.61
3.01
4.80
0.14
1.00
Final Report
30 September 2008
EPA/ORD
-------
174
APPENDIX J
Summary of chemistry data for surface water sampled from within Red Cove Study Area
adjacent to Shepley's Hill Landfill.
Final Report 30 September 2008 EPA/ORD
-------
175
Table J.1. Summary of chemistry data for groundwater samples collected from RCTW wells adjacent to Shepley's Hill Landfill. The following abbreviations are
used within the table: ND = not detected, NS = not sampled, MDL = method detection limit, QL = quantitation limit, ft above sed = feet above sediment.
Location
IC1
IC2
MC1
MC2
SW01
SW02A
SW02B
SW03
SW04
SW05
Date
NS
5/17/2006
5/17/2006
5/17/2006
NS
NS
NS
4/23/2007
4/23/2007
8/20/2007
8/20/2007
9/12/2007
9/12/2007
Height
(ft above sed)
0.46
0.16
3.36
0.82
1.68
0.86
0.45
2.79
1.97
1.15
0.33
3.03
2.21
1.39
0.57
2.46
1.64
0.82
0.41
2.89
2.07
1.25
0.43
2.26
1.44
0.62
2.36
1.54
0.72
MDL
QL
As
mg/L
~
0.014
0.006
0.265
~
~
~
0.010
0.012
0.008
0.072
0.003
0.003
0.007
0.107
0.020
0.021
0.058
0.506
0.019
0.020
0.052
0.159
0.019
0.020
0.136
0.016
0.015
0.045
0.00002
0.0001
Fe
mg/L
~
2.41
0.43
56.4
~
~
~
1.05
1.14
0.72
15.1
0.24
0.50
1.25
34.4
0.70
1.19
5.86
50.7
0.53
0.59
2.42
11.4
0.36
0.26
8.98
0.11
0.22
1.84
0.005
0.017
Mn
mg/L
~
0.40
0.17
1.07
~
~
~
0.20
0.19
0.18
0.85
0.13
0.14
0.28
1.15
0.06
0.17
0.62
1.19
0.03
0.06
0.29
0.60
0.02
0.07
0.53
0.04
0.06
0.10
0.001
0.004
Ca
mg/L
~
11.2
7.6
38.2
~
~
~
9.3
9.4
8.8
25.3
7.8
7.8
9.9
42.1
15.6
16.0
18.6
47.6
14.9
15.2
17.0
23.6
14.5
14.4
18.4
15.7
16.2
16.1
0.03
0.08
K
mg/L
~
2.16
1.3
8.77
~
~
~
1.7
1.78
1.61
5.42
1.19
1.15
1.7
9.32
1.83
1.83
2.76
10.3
1.8
1.78
2.43
4.31
1.69
1.54
2.39
2.04
2.42
2.38
0.06
0.18
Mg
mg/L
~
2.1
1.49
5.43
~
~
~
1.72
1.71
1.66
3.73
1.51
1.5
1.79
5.83
2.59
2.67
2.95
6.29
2.44
2.53
2.8
3.69
2.47
2.41
2.99
2.55
2.72
2.71
0.03
0.08
Na
mg/L
~
13.4
15.1
18.9
~
~
~
18.6
18.6
18.9
17.5
20.3
19.6
17.4
18.9
28.5
26.9
23.3
22.7
29.3
27.4
25.7
24.2
28.8
28.8
27.9
28.5
28.5
27.5
0.04
0.14
Cl
mg/L
~
20.3
23.6
27.4
~
~
~
31.4
30.5
27.1
26.6
37.4
43.5
37.2
33.7
45.0
42.6
36.1
31.0
47.4
44.3
40.6
36.8
45.3
46.5
44.8
45.2
44.8
44.7
0.100
1.00
S04
mg/L
~
5.91
6.02
0.74
~
~
~
6.39
6.19
5.50
4.64
8.09
7.91
7.63
1.39
3.63
3.61
3.22
0.28
3.69
3.58
3.44
2.71
3.68
3.97
2.88
3.63
3.98
3.72
0.100
1.00
NH3-N
mg/L
~
0.10
0.10
0.08
~
~
~
0.36
0.44
0.29
2.13
0.05
0.02
0.28
5.37
0.13
0.08
0.66
5.99
ND
0.05
0.43
1.64
0.05
0.04
0.81
0.28
0.64
0.54
0.02
0.10
TOC
mg/L
~
NS
NS
NS
~
~
~
3.53
4.41
3.94
2.91
NS
NS
NS
NS
3.9
4.7
3.3
2.9
6.3
4.6
3.9
3.6
5.30
5.19
5.64
4.28
4.04
9.95
0.14
1.00
Final Report
30 September 2008
EPA/ORD
-------
176
APPENDIX K
Tabulated metal concentrations for sediment cores collected from the three transects in Red Cove
as determined by microwave assisted HNOs extraction.
Final Report 30 September 2008 EPA/ORD
-------
177
Core Depth
Transect ID (in.) As Fe
1 101 3.5 3260.0 234000
7 1440.0 158000
10.5 703.0 37100
14 52.6 4100
16 8.2 3030
102 3.5 2900.0 230000
7 1710.0 227000
10.5 1470.0 80200
14 245.0 13800
103 3.5 6940.0 374000
7 2150.0 258000
10.5 1370.0 199000
14 232.0 24500
16 11.6 2420
2 201 2 459.0 30000
4 229.0 25200
6 30.4 5610
8 16.6 3870
10 15.0 6540
12 18.7 8170
14 22.7 9310
201B 2 825.0 60900
4 76.2 12800
6 33.5 9810
8 20.2 7380
10 15.7 6240
12 16.0 7800
14 15.0 7140
16 13.6 6810
18 11.5 6120
20 11.3 5480
Core Depth
Transect ID (in.) As Fe
2 201B 22.25 10.7 5160
202 2 8600 359000
4 6490 362000
Final Report
Microwave-assisted
S
10900
23800
17300
843
<14.7
11400
24300
23100
3850
2480
1730
9800
4690
44.7
6500
7880
489
339
22.9
63
266
18600
2910
1190
46.2
<14.7
<14.7
<14.7
<14.7
<14.7
<14.7
Al
2170
8250
15300
9600
14000
2610
6200
11700
8980
593
12700
23900
8380
7710
11900
7120
8760
10500
13500
16200
15300
5950
13300
15000
13100
14100
13700
13900
11100
9530
10500
Mn
1820
10400
1640
338
116
3360
10600
3660
570
1500
3610
6260
733
123
581
547
325
128
112
140
150
3690
248
138
106
95
111
160
114
90
100
Cr
122.0
1070.0
2410.0
47.2
12.2
95.4
855.0
1930.0
23.9
21.7
26.1
623.0
417.0
10.0
299.0
35.4
18.7
14.6
20.3
21.9
22.2
127.0
26.0
44.9
22.4
24.1
21.9
27.8
16.7
21.8
23.5
Microwave-assisted
S
<14.7
2970
2240
Al
10000
509
361
Mn
88
1280
1520
Cr
36.5
18.9
11.2
HNO3
Cu
23.1
36.4
115.0
2.3
1.7
24.9
25.7
38.7
9.2
0.0
13.2
26.1
11.3
1.6
10.0
3.6
3.3
3.7
2.6
4.2
4.5
18.6
12.6
17.5
5.1
5.5
8.7
7.7
5.1
6.3
5.3
HNO3
Cu
6.9
0
0
Extraction (mg/kg)
Pb
21.6
99.5
133.0
49.6
7.1
23.2
84.2
108.0
5.9
11.2
23.2
66.9
27.4
5.9
33.0
8.9
8.0
9.9
8.1
8.0
7.9
255.0
12.1
6.6
5.7
6.5
6.5
6.2
6.0
4.8
4.6
Zn
147.0
167.0
239.0
9.4
9.5
191.0
129.0
164.0
12.1
28.6
39.3
73.9
42.0
0.0
64.7
14.2
3.2
4.9
9.6
13.2
16.7
287.0
20.9
16.5
14.1
13.0
15.9
14.5
12.7
14.3
11.9
Hg
0.7
11.9
60.1
1.0
0.3
0.4
6.4
38.4
0.4
0.2
0.1
4.6
8.2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Cd
3.1
5.2
1.5
0.0
0.0
3.3
4.9
1.4
0.0
7.5
3.3
3.4
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.8
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Ni
18.5
32.2
21.4
9.6
0.0
20.7
19.8
20.6
12.7
0.0
9.0
18.4
5.9
0.0
20.9
16.5
7.5
6.1
8.0
11.0
16.8
10.0
12.1
26.4
16.0
14.0
14.3
15.5
11.7
13.8
15.3
Si
3300
20200
26100
12200
20700
34400
23100
31900
9440
39700
23800
28700
14600
12800
15800
9850
13000
14600
17200
17900
16400
9680
14300
16100
14800
17900
16500
18300
14400
12400
14200
Extraction (mg/kg)
Pb
4.9
12.5
8.14
30 September 2008
Zn
12.7
32.2
26.7
EPA/ORD
Hg
0.0
0
0
Cd
0.0
3.06
4.53
Ni
22.5
1.72
0
Si
14900
22900
26800
-------
178
6
8
10
12
14
16
18.5
202B 2
4
6
8
10
12
14
17.5
21
24.5
28
32
36
40
203 2
4
6
8
10
12
15.5
19
22.5
26
Core Depth
Transect ID (in.)
204 2
4
6
7.125
11.13
4080
4160
2260
1340
588
326
322
1180
669
649
646
145
32.7
26.8
12
12.5
12.7
13.5
24.2
12.4
23.2
137.0
112.0
79.3
15.6
14.7
24.8
9.1
9.9
10.7
11.3
343000 3670
304000 10600
305000 5970
272000 17400
130000 52700
32000 22100
26700 8940
156000 32500
64000 23100
57500 14100
53000 12600
19000 4070
8920 879
8330 397
5880 <14.7
7340 <14.7
7570 <14.7
8400 <14.7
10100 <14.7
5440 <14.7
8190 <14.7
14600 1140
13000 992
10100 749
4970 <14.7
4980 <14.7
6670 <14.7
5310 <14.7
5780 <14.7
4840 <14.7
6020 <14.7
820 2580
2520 8500
1450 6650
3120 12700
8330 13000
12200 1150
4620 771
7010 12600
12700 2450
11200 1990
8340 1880
9720 1580
14800 1800
14500 847
10700 124
11000 123
14100 167
7760 83
7890 75
4690 50
6360 104
19800 247
19500 213
15800 173
11500 105
8000 56
15400 97
5220 54
5440 74
8560 63
6330 60
13.6
28.1
40.8
204
1650
2530
175
774
2750
812
363
89.8
18.4
11
11.7
20.9
14.6
8.01
9.75
9.9
9.35
37.6
37.4
28.0
18.3
12.9
28.6
9.9
11.7
10.5
11.4
Microwave-assisted
As
1310
1670
1510
397
183
Fe S
87900 2130
106000 1740
116000 712
55100 159
26700 <14.7
Al Mn
24300 2300
20900 2130
13400 1700
16500 1250
23400 856
Cr
136
110
70.1
38.1
32.7
0
0
0
0
26.8
43.6
13.5
20.9
45.8
28
18.8
6.41
5.2
5.66
2.95
3.28
4.56
4.24
4.88
5.9
7.82
9.6
11.9
5.7
5.4
4.2
8.0
5.6
5.9
5.9
3.7
HNO3
Cu
39.2
31.1
21
20.2
28.6
9.07
16.9
23.7
58.6
129
121
23.8
390
238
118
49.5
18.8
20.8
22.4
9.43
7.95
5.77
3.5
4.33
2.7
5.48
12.1
10.9
8.3
5.9
4.6
6.7
3.8
5.4
4.2
4.3
29.5
46.9
42.1
100
202
194
31.1
425
316
139
67.3
17.4
8.18
7.41
9.87
12.5
14.6
12.7
15
10.6
12.7
22.5
20.7
16.0
7.9
8.5
12.4
12.7
13.6
12.7
12.5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.116
0.207
0
0.116
0
0
0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
0.1
0.2
0.1
4.47
4.02
4.07
2.86
0
0
0
0.841
0
0
0
0
0
0
0
0
0
0
0
0.0
0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0
5.91
3.7
9.99
26.4
20.4
9.91
17.1
21
15.7
12.2
7.67
6.07
3.58
5.95
10.3
10.2
7.82
9.84
8.0
8.52
12.3
11.1
9.5
9.5
8.8
15.4
7.9
6.9
6.5
8.2
24400
23400
22000
21000
21000
22500
12900
18100
20100
21200
17800
7650
7690
8800
13500
12700
18100
9180
8920
5260
8270
20000
21500
18600
15800
9950
18100
5190
6530
13100
6770
Extraction (mg/kg)
Pb
90.5
73.1
42.3
34
22
Zn
76.9
70.3
68.1
52.8
58.3
Hg
0
0
0
0
0.47
Cd
0
0
0
0
0
Ni
32.2
28.4
21.7
18.3
32.2
Si
21400
20900
13400
17300
27700
Final Report
30 September 2008
EPA/ORD
-------
179
15.13
19.13
3 301 2
4
6
8
10
12
13
16.5
20
23.5
27
302 2
4
6
8
10
10.5
14
17.5
21
24.5
303 1
3
5
7
9
11
Core Depth
Transect ID (in.)
3 303 13
15
15.5
17.5
19.5
21.5
23.5
10.1
9.65
2540
1710
930
850
556
36.8
19.7
17.9
25.7
24.3
22.4
248
143
92.3
22.4
15.7
16.4
20.1
12.9
14.2
8.91
464.0
51.0
18.3
9.5
8.3
9.0
4330
5700
144000
104000
59800
55700
47000
5600
5650
8050
7060
7890
6010
39100
30400
21500
6420
3760
3480
6530
6020
7430
5660
50400
11500
7420
5900
5830
5520
<14.7 5810
<14.7 6540
6590 9050
7560 9760
9950 10600
12300 7410
13300 6050
399 8620
45.6 11400
<14.7 13800
<14.7 5880
<14.7 7180
<14.7 6530
4070 24100
3160 16000
1240 15200
16 6880
<14.7 5870
<14.7 7420
<14.7 8660
<14.7 4040
<14.7 8700
<14.7 5450
219 11900
<14.7 6330
<14.7 6520
<14.7 8460
<14.7 8560
<14.7 9300
71
101
3370
1810
751
536
489
215
113
104
53
59
60
1380
999
590
131
60
50
79
69
139
110
537
146
100
90
106
103
7.51
9.44
225
104
35.5
39.2
27.6
7.37
10.3
9.4
9.4
12.2
9.6
37.2
21.5
11.1
5.65
4.1
4.46
11.8
7.29
8.92
5.02
22.1
9.4
7.8
7.9
7.9
8.0
Microwave-assisted
As
10.0
11.3
266.0
287.0
244.0
193.0
54.0
Fe
5760
6000
20400
18300
26600
36100
12500
S Al
<14.7 8490
<14.7 6820
7780 12000
8770 8350
9050 5010
9740 6200
1610 7570
Mn
87
94
735
215
338
475
211
Cr
8.2
11.9
751.0
506.0
30.0
17.0
8.3
3.12
3.22
36.2
21.2
16.6
9.72
6.37
0
0
4.4
5.1
6.5
4.6
31.3
18.1
8.6
2.93
0.0
0
3
4.98
7.2
7.29
11.5
6.1
5.9
6.7
4.6
4.1
HNO3
Cu
4.9
4.0
25.2
16.7
6.9
6.3
3.6
3.85
3.34
999
471
104
33
22.3
7.41
6.04
3.8
3.8
4.1
5.5
1040
619
276
44.1
4.6
4.83
5.01
9.86
42
82.2
37.1
12.1
6.4
4.5
4.7
4.4
10.8
12.5
987
400
90.7
35.7
27.1
7.28
10.1
10.9
11.6
12.4
13.2
778
486
201
56.3
9.4
8.73
11.5
17.2
36.9
73.6
71.2
32.5
19.7
14.9
14.4
13.2
0.0409
0
0.06
0
0
0
0
0
0
0.1
0.0
0.0
0.1
0
0
0
0
0.0
0
0
0
0.082
0.095
0.0
0.0
0.0
0.0
0.0
0.0
0
0
7.7
0
0
0
0
0
0
0.0
0.0
0.0
0.0
3.23
1.82
0
0
0.0
0
0
0
0
0
0.0
0.0
0.0
0.0
0.0
0.0
6.09 8880
7.04 9400
12.1 20500
10.6 22500
10.8 25400
10.7 19200
10.1 11100
1.91 11300
3.56 15200
8.9 13500
9.6 7180
10.5 9060
8.7 6690
18.8 17200
15.6 11600
10.7 9620
5.41 6550
3.1 7040
2.58 9830
7.25 8500
5.53 3740
6.39 12500
5.47 7350
13.7 16300
7.1 7570
6.9 7390
5.8 12500
5.7 12600
5.4 14200
Extraction (mg/kg)
Pb
4.6
4.0
53.0
39.8
9.4
5.8
6.8
Zn
14.8
18.2
85.7
54.8
23.1
20.9
12.1
Hg
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Cd
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Ni Si
6.0 12500
5.9 9210
12.2 15300
11.5 15100
16.7 7650
36.2 5200
7.8 7540
Final Report
30 September 2008
EPA/ORD
-------
180
25.5
27.25
29.25
31.25
33.25
35.25
37.25
39.25
27.4
35.7
44.9
28.6
26.1
22.1
15.4
15.4
7370
9360
12700
7960
7380
7250
5430
6570
<14.7
<14.7
<14.7
<14.7
<14.7
<14.7
<14.7
<14.7
9130
15300
16600
11700
11000
11000
6090
7120
103
163
190
117
131
122
73
89
10.8
20.5
32.9
15.3
12.8
14.0
9.1
14.5
<2.56
4.5
3.6
<2.56
3.5
4.5
3.4
4.0
4.2
5.9
6.5
4.6
4.6
4.9
4.0
4.2
17.1
17.8
21.0
14.8
15.7
15.6
14.5
15.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
7.4
11.2
13.1
7.8
7.0
7.3
5.5
7.0
8170
17400
20100
12200
12300
13100
6660
7310
Final Report 30 September 2008 EPA/ORD
-------
181
APPENDIX L
Elemental concentrations as a function of depth for sediment cores collected from the three
transects in Red Cove as determined by microwave assisted HNOs extraction.
Final Report 30 September 2008 EPA/ORD
-------
182
3500-
3000-
2500-
_ 2000-
|
ฃ 1500-
* 1000-
500-
0-
-500-
250000 -
\
\ 200000 -
\
\ _ 150000-
\ E
\ ฃ
\, 7T 100000-
^~^\ "
^"~\^^ 50000 -
^^-^^_^^^^
0-
25000-
X,
\x 20000-
^x
N. _ 15000-
\ ฃ
\ - 10000-
\> 5000-
^~~~~-^^
o-
/^X^
/ \
/ \
/ \
\
\
\
2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16
Depth (in.) Depth (in.) Depth (in.)
16000-
14000-
12000-
10000-
Q.
3 8000 -
6000-
4000-
2000-
12000n
/\ 10000-
/ ^\ /
/ \^ / 8000-
/ \/ 1" 6000-
/ ง 4000 -
/
/ 2000 -
/
/ 0-
2500-
A
/ \ 2000-
/ \
/ \
/ \ _ 1500-
/ \ ฃ
/ \ ~ 1000-
/ \
/ \ 500-
X_^^^
^^^-^_^
ฐ"
/\
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16
Depth (in.) Depth (in.) Depth (in.)
120-
100-
80-
I 60:
O 40-
20-
0-
140-
A
/ \
/ \
/ \
/ \ 100-
/ \
/ \ _80
/ \ g 80-
/ \ ฐ-
/ \ * Bฐ~
^-^ \ ฐ" ^
~~~^ \
\ 20 -
\
\
0-
250-
//^ \
// \ 200-
/ \
/ \ _ 150-
/ \ ฃ
/ \ ^ 100-
/ \
/ \ 50-
\
0-
,/\
/ \
^^/ \
______ -^^^ \
\
\
\
\
2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16
Depth (in.) Depth (in.) Depth (in.)
Core SCT0101
Final Report
30 September 2008
EPA/ORD
-------
183
3000
2500-
2000-
^
3 1500-
<2
1000-
500-
o
zouuuu -
\ 200000 -
\^
\,
\s 150000-
^Ss . "E
~~ -^ 3 100000-
\^ ฃ
\s 50000 -
X,^
\ 0-
\ 25000 -
\
\
\ 20000 -
\
\ -5- 15000-
\ ฐ~
\ "" 10000-
^\
^\^ 5000 -
n
2 4 6 8 10 12 14 2 4 6 8 10 12 14 2 4 6 8 10 12 14
Depth (in.) Depth (in.) Depth (in.)
12000-
10000-
_ 8000 -
1
~ 6000 -
4000-
2000-
12000 n
/^^^^^ 10000-
/ ^
/ \ 8000 -
/
/ -
/ 3
// J 4000 -
,/ 2000 -
0-
2000-
/\
/ \
/ \ 1500-
/ \
/ \
/ \ Q. 1000-
/ \ ฐ~
/ \ 0
^\^ 500-
0-
/\
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
\
2 4 6 8 10 12 14 2 4 6 8 10 12 14 2 4 6 8 10 12 14
Depth (in.) Depth (in.) Depth (in.)
40-
35-
30-
Q.
Q.
~ 20-
O
15-
10-
5
120 -,
/\ 100-
/ \
/ \ ,,
/ \
/ \
\ ฃ 40-
\
\ 20-
\
\
0-
,-A 200-
^^ \
^^ \
^^ \
/ \
/ \ 1 100-
/ \ t -
/ \
\
\
0-
\^
^\^
^^^^^^ \
\
\
\
\
\
\
2 4 6 8 10 12 14 2 4 6 8 10 12 14 2 4 6 8 10 12 14
Depth (in.)
Depth (in.)
Depth (in.)
Core SCT0102
Final Report
30 September 2008
EPA/ORD
-------
184
7000-
6000-
5000-
_ 4000-
E
a 3000-
tn
** 2000 -
1000-
0-
1000
400000-
\ 350000-
\ 300000-
\ 250000-
\
\ I" 200000-
\ ฐ-
\ - 150000-
^~~~~~~_ ^"
^~~~- ~-^_^ 100000-
^~~~-^^^ 50000-
- o-
cnnnn
10000-
^x
\, 8000-
\^^
X6000-
?
g
- 4000-
2000-
0-
A
/\
/ \
/ \
/ \
/ \,
/ \
/ \
/ \
/ \
~ " ~^ \
\
2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16
Depth (in.) Depth (in.) Depth (in.)
25000-
20000-
_ 15000-
E
~ 10000-
5000-
0-
7000 n
/\ 6000-
/ \
/ \ 5000-
/ \
/ \ 4000-
/ \ ^
/ \ 3 3000-
/ \ ~
/ V |
/ 2000-
/
/ 1000-
0-
700 -,
/\ 600-
/ \ 500-
/ \
/ \ 400-
/ \ ฃ
/ \ 3 300-
/ \ u
/ \ 200-
/ \
\ 100-
^~" 0-
r\
/ \
I ^x
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16
Depth (in.) Depth (in.) Depth (in.)
30^
25-
20-
~ 15
E
o.
O.
= 10-
5-
0-
70-
/\
/ \
/ \ 5ฐ:
/ \ "E" 40
/ \ Q.
/ \ S "
/ \ f 3ฐ-
/ \ '^
/ \ 10-
n
80^
A 7ฐ-
/\
/\
/ \
/ \ f 40-
/ \ ~ 3ฐ"
/ \ ^ 20-
^ \
^^ \
^^ \ 10-
\ 0-
/'\
/ \
/ \
^^y \
^^-^^^ \
\
\
\
\
\
\
\
2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16
Depth (in.) Depth (in.) Depth (in.)
Core SCT0103
Final Report
30 September 2008
EPA/ORD
-------
185
400-
300-
Q.
S 200-
<
100-
0-
> 30000 -
\
\
\ 25000 -
\
\ 20000 -
_ 15000-
\ 111
\ 10000-
\
V_____ 5000 -
n
\ 8000 -
^^
\ 6000 -
\
\
\ 1. 4000-
\ ^
\ ^_____ 2000 -
~~~~^ ^^^~^
0-
./\
,^ \
^ \
\
\
\
\
\
\
V ________^ ^
2 4 6 8 10 12 14 2 4 6 8 10 12 14 2 4 6 8 10 12 14
Depth (in.) Depth (in.) Depth (in.)
16000-
14000-
f 12000-
Q.
Q.
"-*
< 10000-
8000-
6000
/~~^^^ 600-
/
/ 500-
/
/ 400-
\ / ^"
\ / c 300-
\ // 200 -
\ x
\ x^
100-
2 4 6 8 10 12 14
300-
\^ 250-
\ 200-
t~
\ *i
\ ฐ 100-
\
\ 50-
0-
2 4 6 8 10 12 14
\
\
\
\
\
\
\
\
\
\
\
\
V____^
2 4 6 8 10 12 14
Depth (in.) Depth (in.) Depth (in.)
10-
8-
-
a 6-
o
4-
2
35-
\
\
\ 30-
\
\
\ ~K~
\ *
\ Q.
\ S 20-
\ f
\ /-
~~~\ / 10-
c
70 -,
__
\
\
\ 50-
\
\ 40-
t.
\ -30"
\
\
0-
\, ^^~^~~~~^
\
2 4 6 8 10 12 14 2 4 6 8 10 12 14 2 4 6 8 10 12 14
Depth (in.) Depth (in.) Depth (in.)
Core SCT0201
Final Report
30 September 2008
EPA/ORD
-------
186
800-
600-
_
1 400-
*-'
<
200-
g
70000 n
I
\ 60000-
\ 50000-
^. 40000-
&.
\ Q.
\ 30000-
\
\ 20000-
\~____ 10000-
n
20000-
\
\ 15000-
\
\ | 10000-
\ ^
\ "*
\ 5000-
^^_^^
\
\
\
\
\
\
0 5 10 15 20 25 0 5 10 15 20 25 0 5 10 15 20 25
Depth (in.) Depth (in.) Depth (in.)
16000^
14000-
12000-
1
S 10000-
<
8000-
6000
4000 n
/\ 3500-
/ \ ~-^-.
/ \/ "A 3000-
/ \
/ \ 2500-
/ \ 1 2000-
/ X/""^ f 1500
/ 1
/ 1000-
/
/ 500
0-
140-
\ 120-
\
100-
\
\ 1 80~
\ r so-
\
\ 40-
\
\ 20-
n
\
\
\
\
\
\
\
VA__ /
^
0 5 10 15 20 25 0 5 10 15 20 25 0 5 10 15 20 25
Depth (in.) Depth (in.) Depth (in.)
20 1
18-
16-
14-
"
3 1ฐ-
8-
6-
4
300 n
\ h 250~
\ A
\ / \
\ / \
V \ ~ฃ 150-
\ ~
\ ฃ 100-
\ /^\
U^-/ \.,/ ~~~/ 0-
300-
\
\ 250-
\
\ 200-
t~
"
\ ~<=
\ N 100-
\ 50-
0-
\
\
\
\
\
\__
0 5 10 15 20 25 0 5 10 15 20 25 0 5 10 15 20 25
Depth (in.) Depth (in.) Depth (in.)
Core SCT0201B
Final Report
30 September 2008
EPA/ORD
-------
187
10000^
8000-
6000-
1
S 4000 -
2000-
0-
400000^
350000-
\ 300000-
\
\ 250000-
\
\
\ | 200000-
\ ^ Q.
\ 'JT 150000-
V^^ 100000-
^^-^^^
^~--^^^^ 50000-
0-
60000^
^~~^\ 50000-
-^
^~~> 40000-
\
\ -g- 30000-
\ ฐ-
\ U> 20000-
\
\ 10000-
\
0-
A
/ \
/ \
/ \
/ \
/ v^^
y N.
/ \
// ^--s
0 2 4 6 8 10 12 14 16 18 20 0 2 4 6 8 10 12 14 16 18 20 0 2 4 6 8 10 12 14 16 18 20
Depth (in.) Depth (in.) Depth (in.)
14000^
12000-
10000-
8000-
~ฃ
a 6000 -
4000-
2000-
0-
t
14000^
A 12000-
/ \
/ \ 10000-
/ \
/ \
/ \ 8000-
/ \ ^
/ \ a. 6000-
/ \ "e"
/ S 4000-
X^-^^// 2000-
0-
,- -I 2500-
/ \ 2000-
/ \
/ \
/\, / \ 1500-
/ \ &
/ \ ~ 1000-
/ \ ฐ
J \ 500 -
-
A
A
I \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
) 2 4 6 8 10 12 14 16 18 20 0 2 4 6 8 10 12 14 16 18 20 0 2 4 6 8 10 12 14 16 18 20
Depth (in.) Depth (in.) Depth (in.)
50^
40-
30-
E"
1 20-
0
10-
Q
140^
A 120-
A 100:
/ \
/ \
/ \ ? 8ฐ:
/ \ t 6ฐ-
/ \ f 40-
/
/ 20-
/
0-
/~"~\ 200-
\
\
/ \ 1 1ฐฐ-
/ \ N
/ \
^^J \ 50-
- -^^^
n
~~~~~^
/ \
/ \
/ \
/ \
/ \
/ \
/ \
- -^ *
0 2 4 6 8 10 12 14 16 18 20 0 2 4 6 8 10 12 14 16 18 20 0 2 4 6 8 10 12 14 16 18 20
Depth (in.) Depth (in.) Depth (in.)
Core SCT0202
Final Report
30 September 2008
EPA/ORD
-------
188
1200-
1000-
800-
| 600-
< 400-
200 -
0 -
160000-
\
\ 140000-
\ 120000-
\
\
\ 100000-
I 1. 80000-
~
\ ฃ 60000-
\
\ 40000-
\
V 20000-
\
0-
35000-
l 30000-
25000-
l
20000-
0.
I S 15000-
\^^ (/)
\, 10000-
\
\ 5000-
0-
\
\
\
\
\
\
s
\
\
\
\
V
0 5 10 15 20 25 30 35 40 45 05 10 15 20 25 30 35 40 45 05 10 15 20 25 30 35 40 45
Depth (in.) Depth (in.) Depth (in.)
16000^
14000-
12000-
f 10000-
Q.
Q.
< 8000 -
6000-
4000
14000^
r\ A
A. / \ / \ 10000-
l\ \ / \
\ / V7 \ 8000-
\ / \ |
y \ ~ 600ฐ-
1 V s
/ \ 4000-
\
\ ,
\ / 2000-
0-
3000^
2500-
2000-
f 1500-
Q.
Q.
O 1000-
l^__^ 500-
^^~~- 0
A
I
I
I \
I \
I I
I
\
0 5 10 15 20 25 30 35 40 45 05 10 15 20 25 30 35 40 45 05 10 15 20 25 30 35 40 45
Depth (in.) Depth (in.) Depth (in.)
50 -,
40-
30-
f
g 20-
Q
10-
0-
\
400-
A
\
/ \
/ \
/ \ 1 2ฐฐ~
\ f 150-
100-
^__^^ ^^____^-- 50-
0-
cn
500^
\
\ 400-
\
\ 300-
\ 1
\ S 200-
\ c
\ N
\
\ 100-
v__^
0-
\
\
\
\
\
\
\
\
0 5 10 15 20 25 30 35 40 45 05 10 15 20 25 30 35 40 45 05 10 15 20 25 30 35 40 45
Depth (in.) Depth (in.) Depth (in.)
Core SCT0202B
Final Report
30 September 2008
EPA/ORD
-------
189
140-
120-
100-
p- 80 -
60-
(/)
40-
20-
0-
\ 14000-
\ 12000-
\ 1. 10000-
\ -
\ ill
\ 8000 -
\ X-,
\__/ \^ 6000 -
/innn
\1000-
800-
_ 600-
\ S 400
\ "
\ 200-
\
\ /^^X ^ 0
onn
V
\
\
\
\
\
\
\
\
0 5 10 15 20 25 30 05 10 15 20 25 30 0 5 10 15 20 25 30
Depth (in.) Depth (in.) Depth (in.)
20000 -
18000-
16000-
14000-
E"
g; 12000-
"* 10000-
8000-
6000-
4000
" ~\ 250-
\
\ 200-
\ A ? '
\ \ s 1ฐฐ-
1 \ /\
\ / ""'--.
\ /
40 1
\ ^
\ 35"
\
\
\
\ I25-
\ ~ '
\ 0 20-
\ /X 15"
\ / x^ ,~^^~~~~~~~~~~^^_
10-
~~~~\
\
\
\ A
\ \
\ \
\ \ \
^ \
\
0 5 10 15 20 25 30 05 10 15 20 25 30 0 5 10 15 20 25 30
Depth (in.) Depth (in.) Depth (in.)
12-
10-
=-
3
0
6-
4-
A
/ \
/ \
/ \
\
\ ~
\ \ Q. 8-
\ /\ Q-
/\ ฃ
\ / \
\ / \_ \
^~~A / \
\ / \
\ 4-
24 1
\ 22-
\ 20-
\
\
\
\
\ c
\ Q-
\ Q- -1 A
\ z
\ A N 12-
\ /\
\ A \ /\ 1ฐ-
\ / ^\
\/ s~
c
\
\
\
\
\
\
\
\
\
\
\
\
\ / ~
\ /
\ /
\ /
*-^"^
0 5 10 15 20 25 30 05 10 15 20 25 30 0 5 10 15 20 25 30
Depth (in.)
Depth (in.)
Core SCT0203
Depth (in.)
Final Report
30 September 2008
EPA/ORD
-------
190
2000 ^
1500-
g- 1000-
Q.
Q.
tfl
< 500-
Q
120000-
/\^
/ \, 100000-
/ \
\ 80000 -
\ a. 60000 -
01
\ "- 40000 -
I
^~~~~^ 20000 -
^~^-^__
0-
2500^
,^^\ 2000-
/ \
/ \
/ \
\ 1500-
\
\
\ 1. 1000-
\
\, 500-
\^^
^~\
^^\ 0
cnn
\
N.
\
\
\
\
\
\
\
\
\
\
\
\
\
\
0 5 10 15 20 0 5 10 15 20 05 10 15 20
Depth (in.) Depth (in.) Depth (in.)
25000 -
20000 -
___ ^
1. 15000-
<
1 0000 -
5000-
2500^
\, A, 2000 -
\ / \
\ / \ 150ฐ-
\ / \ f
V \ 3: 1000-
\ c
\ S
\
\ 500-
\
\
0-
140-
\, 120-
\ 100-
\
\ 80-
^\ t 60-
\, 40-
\ 20-
0-
\
\
\
\
\
\
\
\
\
\
V- ___^^
^-.
0 5 10 15 20 0 5 10 15 20 05 10 15 20
Depth (in.) Depth (in.) Depth (in.)
40-
35-
30-
25-
t 20-
3 15-
10-
5-
o
\
\ 80-
\
\ S^\. ^ ~
V_X \ i
^^'^ \ S 40-
\ ^
\
\ 20-
\
\ o-
80-
\
\
\
\ 60-
\
\ -P- 50-
\ 1
v^ c
^~~\ N
^^~~^^ 30-
^\ 20-
^
10-
"\__^
A
\
\ ^ -~~~~~"~~~~~~\
\
\
\
\
\
\
\
^ ~~ ~~
0 5 10 15 20 0 5 10 15 20 05 10 15 20
Depth (in.) Depth (in.) Depth (in.)
Core SCT0204
Final Report
30 September 2008
EPA/ORD
-------
191
2500-
2000-
_ 1500-
I
a.
7T 1000-
*
500-
0-
1 60000 -,
\ 140000-
\
\ 120000-
\
\
\ 100000-
\
\ f 80000 -
V_^ oT 60000 -
^~~\ "-
\ 40000 -
\
\ 20000 -
0-
14000-
\
\ 12000-
\
\
\ 10000-
\
\ 8000 -
\ ?
\ ฃ 6000 -
V^ ^ ---
^"\ 4000 -
\
\ 2000 -
\ 0-
onnn
s\
/
/ \
/
/
/
^
\
L
0 5 10 15 20 25 30 05 10 15 20 25 30 0 5 10 15 20 25 30
Depth (in.) Depth (in.) Depth (in.)
14000-
12000-
1. 10000-
Q.
^
8000-
cnnn
DUUU -
3500-
/\ 3000-
/ \
/ \
/ \ 2500 -
/ \
\
/ \ \ ~ 1500-
\ \ ^
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Depth (in.)
25 30
10 15 20
Depth (in.)
25 30 0
10 15 20
Depth (in.)
10 15 20
Depth (in.)
25 30
Final Report
30 September 2008
10 15 20 25 30 0
Depth (in.)
Core SCT0301
EPA/ORD
10 15 20
Depth (in.)
25 30
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5 10 15 20 25 30 35 40
Depth (in.)
5 10 15 20 25 30 35 40
Depth (in.)
Core SCT0303
0 5 10 15 20 25 30 35 40
Depth (in.)
Final Report
30 September 2008
EPA/ORD
------- |