PB99-963905
EPA541-R99-009
1999
EPA Superfund
Record of Decision:
Boarhead Farm Site
Bridgeton Township, PA
11/18/1998
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SUPERFUND PROGRAM / ^ ^
RECORD OF DECISION f
V^ni^y
Boarhead Farms Superfund Site
Bridgeton Township
Bucks County, Pennsylvania
NOVEMBER 1998
DECLARATION
SITE NAME AND LOCATION
The Boarhead Farms Superfund Site
Bridgeton Township, Bucks County, Pennsylvania
STATEMENT OF BASIS AND PURPOSE
This decision document presents the final selected remedial action for the Boarhead Farms
Superfund Site (Site). The remedial action was selected in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended by
the Superfund Amendments and Reauthorization Act of 1986 (SARA); and the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP). This decision is based on the
Administrative Record for the Site.
The Commonwealth of Pennsylvania has concurred with the selected remedy.
ASSESSMENT OF THE SITE
Pursuant to duly delegated authority, I hereby determine pursuant to Section 106 of CERCLA,
42 U.S.C. § 9606, that actual or threatened releases of hazardous substances from this Site, if not
addressed by implementing the response action selected in this Record of Decision (ROD), may
present an imminent and substantial endangerment to the public health, welfare, or environment.
DESCRIPTION OF SELECTED REMEDY
The selected remedy described below is the only planned action for the Site. This remedy
addresses contaminated soil hot spots, buried drums, contaminated groundwater, and offsite
drinking water.
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The selected remedy includes the following major components:
1) Soil Aeration and Treatment of VOC Hot Spots: Mechanical aeration of soil hot spot areas to
remove high levels of VOCs (primarily TCE and benzene) in a temporary onsite treatment
building equipped with carbon filters.
2) Excavation and Off site Disposal of Buried Drums: Excavation and offsite disposal of buried
drums to reduce the potential for continued migration of contaminants to the soil and
groundwater as well as to reduce exposure risk.
3) Groundwater Extraction, Metals Precipitation, and Air Stripping: Continued extraction and
treatment of VOCs in groundwater via the existing interception trench and air stripping treatment
system and addition of a metals precipitation unit to remove inorganics to reduce contaminants in
the groundwater to below Maximum Contaminant Levels (MCLs).
4) Installation of Additional Monitoring Wells: Installation of additional (specific number to be
determined during remedial design) monitoring wells to monitor the effectiveness of the remedial
action. These wells will be placed in areas along the perimeter of the Site to permit monitoring
of migration, if any, of contaminated groundwater.
5) Institutional Controls and Monitoring: Implementation of institutional controls to protect the
integrity of the remedial action components and the previously installed cover soils to ensure
continued protectiveness of the remedy.
6) Residential Water Treatment: Continued maintenance of the granular activated carbon (GAC)
filters that were installed on affected residential water wells in the surrounding area to prevent
exposure to contaminated groundwater from the Site.
7) Phytoremediation: Performance of treatability studies in the main former disposal areas of the
Site to determine whether phytoremediation is a viable treatment technique to aid in the removal
of VOC and metals contamination in the groundwater.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment and is cost effective.
EPA believes that the selected remedy will comply with all Federal and State requirements that
are legally applicable or relevant and appropriate to the remedial action. The selected remedy
utilizes a permanent solution to the maximum extent practicable and satisfies the statutory
preference for a remedy that employs treatment that reduces toxicity, mobility, or volume.
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Because this remedy will result in hazardous substances, pollutants, or contaminants remaining
onsite, a review by EPA will be conducted no less often than every five years after initiation of
the remedial action to ensure that the remedy continues to provide adequate protection of human
health and the environment.
Abraham Ferdas, Director • Dai
Hazardous Site Cleanup Division
EPA Region III
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TABLE OF CONTENTS
PART II - DECISION SUMMARY
I. SITE NAME, LOCATION, AND DESCRIPTION 1
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES 1
III. HIGHLIGHTS OF COMMUNITY PARTICIPATION 3
IV. SCOPE AND ROLE OF THE RESPONSE ACTION 4
V. SUMMARY OF SITE CHARACTERISTICS 4
A. Topography 4
B. Climate 4
C. Hydrology 4
D. Land Use 5
VI. NATURE AND EXTENT OF CONTAMINATION 6
A. Surface Soil . 6
B. Subsurface Soil 7
C. Surface Water 8
D. Sediment 9
E. Groundwater 9
F. Hot Spots 11
G. Buried Drums 11
H.Air 11
VII. SUMMARY OF SITE RISKS 12
A. Human Health Risks 12
1. Identification of Chemicals of Potential Concern 12
2. Exposure Assessment IS
3. Toxicity Assessment 16
4. Human Health Effects 17
5. Risk Characterization 17
B. Ecological Risk Assessment 18
C. Conclusions 19
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VIII. DESCRIPTION OF ALTERNATIVES
IX. COMPARATIVE EVALUATION OF ALTERNATIVES
X. SELECTED REMEDY AND PERFORMANCE STANDARDS
STATUTORY DETERMINATIONS
XI.
XII. DOCUMENTATION OF CHANGES FROM PROPOSED PLAN
19
24
30
39
A. Overall Protection of Human Health and the Environment 39
B. Compliance with Applicable or Relevant and Appropriate Requirements 39
(ARARs)
C. Cost Effectiveness 40
D. Utilization of Permanent Solutions and Alternative Treatment (or Resource 40
Recovery) Technologies to the Maximum Extent Practicable
E. Preference for Treatment as a Principal Element 40
41
APPENDIX A - TOXICOLOGICAL PROFILES OF SELECTED SITE CONTAMINANTS
APPENDIX B - FIGURES
APPENDIX C - TABLES
PART III - RESPONSIVENESS SUMMARY
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FIGURES
Figure 1 - Site Location
Figure 2 - Site Features and Areas of Investigation
Figure 3 - Site Location and Land Use
Figure 4 - Monitoring Well and Test Pit Locations
Figure 5 - Distribution of Inorganics and Organics in Soil
Figure 6 - Residential Well Locations
Figure 7 - Hot Spot Removal Areas
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FIGURES
Figure 1 - Site Location
Figure 2 - Site Features and Areas of Investigation
Figure 3 - Site Location and Land Use
Figure 4 - Monitoring Well and Test Pit Locations
Figure 5 - Distribution of Inorganics and Organics in Soil
Figure 6 - Residential Well Locations
Figure 7 - Hot Spot Removal Areas
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TABLES
Table 1 Areas of Investigation
Table 2 Monitoring Well Locations Where Federal MCLs or State HALs Were Exceeded
in Groundwater
Table 3 Preliminary Remediation Goals for Groundwater
Table 4 Preliminary Remediation Goals for Soil
Table 5 Area Specific Exceedances of Preliminary Remediation Goals for COPCs in
Subsurface Soil
Table 6 Residential Wells with MCL Exceedances (through 12/95)
Table 7 Summary of the COPCs Identified Through the Human Health RA
Table 8 Toxicity Values Used in the Human Health Assessment
Table 9 Human Health Risks at the Hoarhead Farms Site
Table 10 Summary of Alternatives
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PART III - RESPONSIVENESS SUMMARY
OVERVIEW
BACKGROUND
I. SUMMARY OF COMMENTS AND CONCERNS RAISED AT THE PUBLIC
MEETING
II. SUMMARY OF COMMENTS AND QUESTIONS RECEIVED IN WRITING
DURING THE PUBLIC COMMENT PERIOD
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RECORD OF DECISION
BOARHEAD FARMS SUPERFUND SITE
PART II - DECISION SUMMARY
I. SITE NAME, LOCATION, AND DESCRIPTION
The Boarhead Farms Superfund Site (Site) is located in Bridgeton Township, Bucks County,
Pennsylvania. The Site consists of approximately 120 acres on Lonely Cottage Road in Upper
Black Eddy, in the western part of Bridgeton Township (Figure 1). Approximately one half of
the Site is wooded and nonwooded wetlands. Other features of the Site include open field areas,
four manmade ponds, wooded uplands, a farmhouse, office, and stable (Figure 2).
Aerial photographs indicate that the property was heavily wooded prior to 1969. In 1969
Manfred DeRewal Sr. (hereafter referred to as "Mr. DeRewal") incorporated Boarhead
Corporation (BHC) and DeRewal Chemical Company (DCC) and acted as president of both
companies. BHC purchased the Site in 1969 and remains the current legal owner. Keystone
Excavation Company once leased a portion of the Site to store and maintain excavating and
hauling equipment.
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES
Prior to his tenure at Boarhead Corporation, Mr. DeRewal operated the Revere Chemical Site in
Revere, Bucks County, Pennsylvania from 1965 to 1969. The Pennsylvania Department of
Environmental Resources (PADER), now known as the Pennsylvania Department of
Environmental Protection (PADEP), ordered the Revere Site closed in 1970 due to numerous
pollution violations. During legal proceedings, Mr. DeRewal claimed that he moved 260,000
gallons of "liquid waste" from Revere between July 17,1970 and August 4,1970. No
documentation was available to indicate where the waste was disposed. The Boarhead Farms
Site is four miles from Revere.
In the early 1970s, the Pennsylvania State Police began receiving complaints of dead fish, dead
plant life, and foaming along the edges of a stream on property adjacent to the Boarhead Site.
The complaint alleged that the pollution was caused by acid dumped into the stream from tank
trucks at the Site. The Bucks County Department of Health (BCDOH) investigated the
complaints and observed pungent odors at the Site. BCDOH also noted drums aboard an open
trailer, unused drums awaiting burial, and large empty tanks awaiting removal. In addition,
BCDOH reported a bulldozer onsite burying old drums. According to statements by Mr.
DeRewal, the old empty drums were crushed and buried on the Boarhead Site property. BCDOH
also noted that approximately 40 drums were filled with an unspecified solvent and staged above
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ground. In addition, empty tanker trucks were parked on the Site. BCDOH attempted to inspect
the Site further, but Mr. DeRewal denied access in the absence of a search warrant.
On March 5, 1973, BCDOH obtained a search warrant and inspected the Site. BCDOH's "Waste
Discharge Inspection Report" recorded improperly stored chemicals resulting in the spillage of
liquid and solid waste on the ground. Chemicals were observed leaking from 55-gallon drums,
in waste pools along the access road, and in onsite lagoons and vats. Hazardous materials were
also stored improperly in leaking drums and broken bags. Chemicals documented at the Site
included copper ammonium sulfate, paint solvents, arsenic pentoxide, pesticides, and copper
naphtholate. A BCDOH memorandum identified a cleared area northeast of the onsite office as
the location of an unspecified amount of buried drums.
On March 21,1973, BHC and Mr. DeRewal executed an agreement with PADER to address
environmental conditions at the Site. It was agreed that all industrial and solid waste, buried
drums, and contaminated soil would be removed from the Site. Storing of hazardous waste,
landfilling operations and parking of tanker trucks were banned. In October 1973, however, a
neighbor noticed discoloration and foaming in a stream on his property. BHC was found in
violation of the Pennsylvania Clean Streams Law for releasing chemical waste without a permit.
The contamination came from a leaking tanker truck carrying ferrous chloride. The truck had
discharged its entire load, approximately 3,000 gallons of ferrous chloride, at the Site.
Groundwater and soil samples taken from the Site hi July 1974 by a consultant hired by
Boarhead Corporation revealed pH readings of 2.9. The presence of chloride, iron, chromium,
copper, zinc, and nickel were also noted. In April 1976, approximately 4000 gallons of liquid
ammonia were released from an open valve on a tanker truck. The ammonia odor was noted by
BCDOH in the open fields, near the ponds, and on Lonely Cottage Road. In September 1976, a
new complaint about an ammonia odor was reported. The Bridgeton Police Department arrived
at the Site and found a strong ammonia smell and a heavy fog by a storage tank. The tank
contained sulfuric acid and had developed a leak, creating a sulfuric mist. Thirty-four local
residents were evacuated as a result.
On October 15,1976, the Court of Common Pleas of Bucks County issued an order to Manfred
DeRewal and Boarhead Corporation prohibiting all chemicals from entering the Site in amounts
greater than necessary for normal household use. All chemicals on the property were ordered
removed within seven days.
EPA conducted a site inspection (SI) of Boarhead Farms in May 1984 and issued a final SI report
on January 20,1986. EPA issued a Hazardous Ranking System (HRS) report on September 4,
1987. The HRS report scored the Site at 39.9. EPA placed the Site on the National Priorities
List (NPL) on March 31,1989. EPA conducted a Remedial Investigation (RI) and Feasibility
Study (FS) for the Site. The RI was completed hi January 1997. The Feasibility Study (FS) was
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completed in July 1997. The Proposed Plan for comprehensive Site cleanup was issued in
January 1998.
EPA has conducted three removal actions at the Boarhead Farms Site. During the first two, one
each in 1992 and 1993, over 2500 buried drums were located, excavated and disposed of offsite,
reducing the contaminant levels in the subsurface soils. The excavated areas were then covered
.with a layer of clean fill to reduce exposure risk. A third removal action to intercept, collect and
treat contaminated groundwater in an onsite treatment facility is continuing at this time. The
interception trench is approximately 1300 feet in length and is located downgradient from the
high VOC and metals concentration areas. The trench intercepts the shallow and intermediate
groundwater flowing through the Site and pumps it to an onsite treatment facility for removal of
VOCs. In addition, residential wells where contamination was found have been equipped with
granular activated carbon (GAG) filters.
A fourth removal action was performed by General Ceramics, Inc. (GCI) pursuant to an
Administrative Order by Consent dated December 11, 1992 (EPA Docket No. III-92-66-DC).
GCI excavated and removed drums and soils contaminated with radioactive wastes. EPA has
determined that all known radioactive wastes have been removed from the Site.
III. HIGHLIGHTS OF COMMUNITY PARTICIPATION
The documents which EPA used to develop, evaluate, and select a remedy for the Site have been
maintained at the Bucks County Library Center, 150 S. Pine Street, Doylestown, PA and at the
EPA Region III Office, Philadelphia, PA.
The Proposed Plan was released to the public on January 5, 1998. The notice of availability for
the RI/FS and Proposed Plan was published in the January 5 and 9, 1998 editions of The
Intelligencer Record and The Morning Call, as well as in the Janu, ry 8, 1998 edition of The
Delaware Valley News. A 30-day public comment period began oa January 5,1998 and was
initially scheduled to conclude on February 4, 1998. By request, the public comment period was
extended until April 5,1998.
A public meeting was held during the public comment period on January 14,1998. At the
meeting, representatives from EPA answered questions about the Site and the remedial
alternatives under consideration. Approximately 30 people attended the meeting, including
residents from the impacted area, potentially responsible parties, and news media representatives.
A summary of comments received during the comment period and EPA's responses are
contained in Part III of this document.
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IV. SCOPE AND ROLE OF RESPONSE ACTIONS
This final selected remedy addresses the threats posed by the release of hazardous substances at
the Site. The primary objective of the remedy described in this ROD is to reduce or eliminate the
potential for human and ecological exposure to contamination at the Site. The selected remedy
outlined on pages 30 to 42 of this ROD will comprehensively address the risks posed by the
release or threat of release of hazardous substances from the Site.
V. SUMMARY OF SITE CHARACTERISTICS
A. Topography
The Site is located in western Bridgeton Township, Bucks County which is in the Triassic
Lowland section of the Piedmont Physiographic Province. The Triassic Lowlands are
characterized by sedimentary rocks of the Newark Supergroup and diabase intrusions. The
sedimentary rocks are primarily continental sandstones and shales, having since eroded to
lowlands. The depth to bedrock varies across the Site, but generally the overburden thickness
increases downslope from the topographic highs on the western and northern parts of the Site.
The overburden thins across a broad low-lying area in the eastern part of the Site.
The Site occupies approximately 120 acres. Half of the area consists of wooded and nonwooded
wetlands, with the remainder being wooded uplands, open fields and ponds. The topography of
the Site is rolling and hilly. The property slopes gently east at a grade of four percent, from a
high of 625 feet above Mean Sea Level (MSL) at the western edges to a low of 540 feet MSL
along Lonely Cottage Road.
B. Climate
The Boarhead Farms Site is in the northeastern part of Bucks County, which is part of the
Southeast Piedmont climatic division. The climate is classified as humid continental, modified
by the Atlantic Ocean. The annual average temperature for most of Bucks County is 53°F.
Annual average precipitation is between 43 to 45 inches. Summer rainfall is generally in the
form of thundershowers, occurring on an average of 21 days from June through August. The
annual average snowfall for most of Bucks County is 30 inches. Snow cover is more frequent
and remains for longer periods of time on north and east facing slopes. According to the U.S.
Department of Agriculture, the growing season is 155 days.
C. Hydrology
There are three hydrogeologic systems at the Site: 1) the shallow groundwater system within the
soil, saprolite, weathered bedrock, and moderately fractured shallow bedrock, 2) the intermediate
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groundwater system within the deep-diabase bedrock, and 3) the deep groundwater system
within the Triassic shale of the Newark Supergroup.
The water table in the shallow groundwater system is a subdued representation of the
topography. The groundwater in the shallow system flows east from the topographic highs in the
western part of the Site toward the former drum-burial areas in the central part of the Site and
then toward the wooded wetlands to the north and south of the access road. A groundwater
divide parallels the access road in the eastern part of the Site. The hydraulic gradient in the
shallow system is steepest in the southwest, near the topographic highs, and flattens as the
groundwater moves east across the Site. The groundwater flow velocity is expected to range
from 1.2 to 364 feet per year beneath the steeper parts of the Site and from 41 to 226 feet per
year beneath the wetlands.
Streams and ponds lose water to the shallow groundwater system in summer when groundwater
levels drop, and gain water in winter when groundwater levels rise. When groundwater levels
are high, the flow off the Site is generally intercepted by surface streams.
Groundwater flow in the intermediate system is primarily through a series of fractures in the
deep-diabase bedrock. Limited data suggest that groundwater flows laterally from the former
drum-burial areas on the Site toward Lonely Cottage Road.
The deep groundwater system has little to no flow since it consists mainly of the underlying
competent bedrock. Literature suggests that the flow in the Triassic shale is primarily in the
direction of strike through fractures, bedding planes, and joints. The flow in the deep system has
local-and regional components due to pumping and fracture distribution, but generally is toward
points of regional discharges, such as the Delaware River.
Free hydraulic connection exists through vertical fractures between the overburden and the
shallow weathered diabase. Since the hydraulic head in the deep groundwater system (i.e., the
Triassic shales) is lower than that of the shallow system, there is a potential for groundwater in
the shallow system to flow downward. Fractures which would allow downward flow, however,
are limited. Shallow groundwater may reach into the Triassic shale downgradient wells, such as
those residential wells east and northeast of the Site, since long open boreholes exist and may
connect the shallow and deep groundwater systems. Hydraulic interconnection between the
diabase and the Triassic shale is more likely to occur at the edges of the diabase than in its
interior.
D. Land Use
The land use in the vicinity of the Site is primarily residential. Two junkyards south and
northwest of the property are the sole known industrial facilities in the immediate area. Several
parcels of Pennsylvania State Gamelands are within 0.5 miles of the Site. Two of the properties
bordering the Site, the Bridgeton Township Sportsman Association (gun club) and Camp Davis
(church camp), are recreational facilities. Bridgeton Elementary School and Bridgeton Athletic
Association ballfields are within one mile of the Site (Figure 3).
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VI. NATURE AND EXTENT OF CONTAMINATION
This section discusses the nature and extent of contamination of surface and subsurface soils,
groundwater, surface water, sediment, air, and hot spot areas. In order to conduct Site
investigations accurately, the Site was divided into areas based on geographic features and
suspected waste-disposal activities (Table 1 and Figure 2).
The media were assessed by cdlecting environmental samples. Analytical data were reviewed for
conformance with usability standards. Usable data were evaluated for distribution of contamiriatl
and were compared with potentially applicable standards. The assessment focused on contaimnts
of potential concern (COPCs) identified in the risk assessment for surface soil, surface water,
sediment, and groundwater. For soil, COPCs selectedbr assessment were based on their potential
for leaching to groundwater. Observed concentrations of chemicals were compared with Site-
specific risk-based concentrations (RBCs) for surface soil, surface wateiand sediment; to maximun
contaminantlevels (MCLs); to PADERhealth advisory limits (HALs) (Table 2)$ite-specific RBCs
for groundwater; and to Site-specific preliminary remediation goals (PRGs) fogroundwater and soi
(Tables 3 and 4). PRGs are site-specific numbers modeled on the basis of possible effects of the
COPCs on both human and ecological receptors.
A. Surface Soil
Surface soil was sampled on a regularly spaced grid pattern throughout the Site. Sampling was
followed by delineation of hot spots at grid nodes where preliminary action levels were exceeded
or more than one organic contaminant was detected during the grid sampling.
Inorganic
Inorganic contaminants of concern were found in the surface soils of the open field areas, eastern
wooded wetlands, and western wooded uplands. These included arsenic (ranging from 1.3 - 11.2
milligrams per kilogram (mg/kg)), beryllium (ranging from 0.14-17.3 mg/kg), cadmium
(ranging from 0.34 - 21.5 mg/kg), chromium (ranging from 15.5-812.0 mg/kg), copper (ranging
from 5.6 - 396.0 mg/kg), and thallium (ranging from 0.48 - 3.30 mg/kg). These concentrations
exceeded the human health RBCs for all areas in which they were detected.
Semivolatile Organic Compounds (SVOCs)
Bis(2-ethylhexyl)phthalate was the only SVOC of concern in the surface soils. Concentrations
were found at a range from 120.0 - 28,000 ug/kg (micrograms per kilogram).
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Volatile Organic Compounds (VOCs)
The VOCs detected in the open field areas are associated with the former drum burial areas or
where surface water from the areas is directed. Moderate to extremely elevated levels of VOCs
which EPA determined were COPCs were detected in samples from the wooded wetlands
associated with test pits. The COPCs in all areas of the surface soils onsite include TCE (ranging
from 2.0 -1000.0 ug/kg), 1,1,1-TCA (ranging from 4.0 -120.0 ug/kg), cis-l,2-DCE (ranging
from 2.0 - 66.0 ug/kg), PCE (ranging from 2.0 - 16.0 ug/kg), and toluene (ranging from 1.0 - 32.
0 ug/kg). Other COPCs in the surface soils include benzene, ethlybenzene, xylenes, and methyl
isobutyl ketone (MIBK).
B. Subsurface Soil
Subsurface soils were sampled to evaluate the nature and extent of contamination around the
former drum-burial areas hi the open fields and wetlands. Distribution of the contaminants do
not suggest a continuous area of contamination, but rather the presence of smaller "hot spots."
Figure 4 shows test pit locations and Figure 5 shows the distribution of contaminants hi soil
(both surface and subsurface soil).
Inorganics
Subsurface soils collected from the open field areas showed high levels of the inorganic metals
cadmium (ranging from 0.25 - 423 mg/kg) and lead (ranging from 1.5 - 11,800 mg/kg). Both
cadmium and lead were detected in the areas associated with test pit locations throughout the
open fields. Cadmium concentrations up to about 50 milligrams per kilogram (mg/kg) and lead
concentrations up to 93 mg/kg were found near the farmhouse.
SVOCs
Bis(2-ethylhexyl)phthalate was the only SVOC found above Preliminary Remediation Goals
(PRGs) in the subsurface soil. The concentrations of bis(2-ethylhexyl)phthalate ranged from 42
to 100,000 ug/kg hi the open field areas.
VOCs
VOCs were detected at high levels throughout the subsurface soils in the open field areas. TCE
was detected up to 2,200,00 ug/kg, PCE up to 15,000 ug/kg, and 1,1,1-TCA up to 94,000 ug/kg.
In addition, benzene was detected near the farmhouse at concentrations up to 113 ug/kg. The
areas with high TCE and benzene concentrations have been designated as soil "hot spots" since
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no specific plume has been identified. The PRGs for TCE, PCE, and 1,1,1-TCA were also
exceeded in Wetland Area 3. ,
Subsurface soil samples were collected from Wetland Area 12 to investigate past disposal
activities in the wetland and to delineate contamination detected during sediment sampling.
PRGs were not exceeded for organic or inorganic contaminants in the subsurface soil samples
collected in Wetland Area 12.
C. Surface Water
Surface water and sediment samples were collected from the four onsite ponds, two onsite
wetland areas, and the unnamed creek, and were compared with those from an offsite pond,
wetland, and creek to determine background concentrations.
Inorganics
RBCs were exceeded for manganese, detected up to 6.360 mg/1, and chromium, detected up to
1.870 mg/1, in Wetland Area 12 . These exceedances do not, however, pose a risk to human
health according to the Site-specific human health risk assessment. Human health RBCs were
not exceeded in surface water samples from Wetland Area 3.
Manganese (ranging from 0.043 - 2.91 mg/1) was found in surface water samples collected in
three culverts that drain Wetland Area 12. These exceedances pose no risk to human health
based on the Site-specific human health risk assessment.
SVOCs
Nitrobenzene was the only significant S VOC detected in onsite surface water samples. Levels of
nitrobenzene were found in Pond 11 ranging from 3.0 - 6.0 ug/1.
VOCs
Low levels of the VOCs 1,1,1-TCA (ranging from 6.0 - 10.0 ug/1), 1,2-DCE (ranging from 5.0 -
15.0 ug/1), and TCE (ranging from 5.0 -17.0 ug/l), were detected in the surface water samples
collected from onsite Ponds 10 and 11. The highest concentrations of organics were detected in
surface water samples collected along the northern edge of Pond 11 and a drainage channel
adjacent to the pond. However, Pond 11 was drained into Wetland Area 12 in the spring of 1993
and has since refilled from precipitation, surface runoff, and groundwater seepage.
Low levels of the VOCs 1,1,1-TCA, 1,2-DCA, 1,2-DCE, PCE, and TCE were detected in surface
water samples collected from the wetlands in the area downgradient of former drum-burial areas,
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and in one culvert that drains Wetland 12. Human health RBCs were not exceeded for these
detections.
D. Sediment
Sediment samples were taken from the onsite ponds and wetlands, as well as from the area
culverts and creeks.
Inorganics
RBCs for four inorganic compounds were exceeded in the sediment samples from the onsite
Ponds 9, 10, and 11. These include detections of arsenic up to 25.6 mg/kg, beryllium up to 5.1
mg/kg, chromium up to 617.0 mg/kg, and nickel up to 2650.0 mg/kg. In addition, chromium was
detected up to 1180 mg/kg in sediment samples from Wetland Area 3.
SVOCs
No SVOCs were classified as COPCs for the sediment samples taken throughout the Site.
VOCs
Elevated levels of 1,1,1-TCA (up to 6 ug/kg), 1,1-DCA (up to 100 ug/kg), 1,2-DCE (up to 13 .
ug/kg), toluene (up to 13 mg/kg), and TCE (up to 1180 ug/kg) were detected in sediment samples
collected from Pond 10. In addition, VOCs were found along the northern and eastern edges of
Pond 11, immediately downgradient from drum-burial areas.
Wetland Areas 3 and 12 showed low levels of VOCs, such as 1,1,1-TCA, 1,2-DCE, toluene,
vinyl chloride, PCE and TCE. Low levels of acetone and pesticides were detected in samples
collected from culverts and creeks associated with the wetland areas; however, these levels did
not exceed RBCs.
E. Groundwater
Groundwater quality was investigated in two groundwater systems at the Site — the shallow
groundwater system (overburden and shallow diabase) and the intermediate groundwater system
(deep diabase). Groundwater quality for the deep groundwater system (Triassic shale) was not
investigated, since the underlying bedrock is considered competent. Data indicate that there is
little flow between the shallow and intermediate systems. Figure 4 shows monitoring well
locations, and Tables 2 and 6 list the specific MCLs that were exceeded in each Site well and
residential well, respectively.
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Select residential wells were sampled during nine separate sampling events between November
1990 and January 1995. MCLs were exceeded in 22 residential wells for at least one
contaminant. Table 6 summarizes residential wells with MCL exceedances and Figure 6 shows
residential well locations.
Inorganics
Wells in the shallow groundwater system throughout the Site showed various levels of inorganic
contaminants exceeding MCLs. These detections include chromium up to 22.8 ug/1, nickel up to
6.68 ug/1, manganese up to 69.20 ug/1, and cadmium up to 1.84 ug/1. In addition, levels of lead,
thallium, antimony, and beryllium exceeded MCLs and are cause for concern. The majority of
the high contamination levels coincide with the contaminated subsurface soils related to the
buried drums found in both the open field and wetland areas.
The intermediate groundwater system showed detections offsite of chromium, lead and nickel in
concentrations just above the MCL. These offsite elevated levels were found sporadically
throughout the study area and are not believed to be Site-related. The samples taken during the
RI/FS in the residential wells had detections of antimony, chromium, thallium, nickel, cadmium,
and lead. The samples taken during the RI investigation showed sixteen residential wells with
detections of at least one inorganic contaminant above the MCL.
SVOCs
The SVOC nitrobenzene was detected in levels up to 130 ug/l in the shallow groundwater system
in the open field areas. Low levels of additional SVOCs were also found in areas throughout the
Site.
Bis(2-ethylhexyl)phthalate was the organic compound detected most often in the residential
wells at concentrations up to 32 ug/1. The affected residential wells have been equipped with
GAC filtration units for removal of all organics.
VOCs
Wells in the shallow groundwater system had extremely high concentrations of VOCs that
exceeded MCLs. These include detections of PCE up to 20,000 ug/1, TCE up to 260,000 ug/1,
benzene up to 300,000 ug/1,1,1,1-TCA up to 140,000 ug/1, cis-l,2-DCA up to 53,000 ug/1,1,2-
DCE up to 35,000 ug/1,1,2 - DC A up to 4700 ug/kg, vinyl chloride up to 910 ug/1, xylenes up to
7000 ug/1, and toluene up to 48,000 ug/1. Other VOC detections include 1,1,2-TCA, 1,1-DCE,
1,2-dichlorobenzene, 1,2-DCP, trans- 1,2-DCE, MIBK, carbon tetrachloride, ethylbenzene, and
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methylene chloride. Low levels of other VOCs and pesticides were also detected. The areas of
high levels of shallow groundwater contamination include Area 2 near the farmhouse and open
field Areas 1,5, and 6, coinciding with the former drum burial areas. In addition, the
downgradient wetlands had high levels of TCE.
Carbon disulfide, cis-l,2-DCE, lead, 1,1,2-TCA, TCE, 1,1-DCE, and PCE were the VOCs
detected in the intermediate groundwater system.
F. Hot Spots
Based on the results of the subsurface soil and groundwater investigations, three areas of
particular concern, or hot spots, were identified. These are areas where free product (LNAPL or
DNAPL) is suspected based on high concentrations of contaminants detected in the soil and
groundwater samples in the area, or visual observation of free product during drum removal.
' Figure 7 shows the approximate location and aerial extent of the hot spot areas. The actual
extent of the hot spot contamination will be determined in the design process.
Hot Spot 1 is hi a wetland area where excavation of drums containing contaminated materials
occurred during the removal actions. Extremely high levels of TCE and high levels of PCE and
1,1,1-TCA were detected in the soil following drum removal. Groundwater from the area
showed high levels of TCE, 1,1,1-TCA, cis-l,2-DCE, 1, 2-DCA, and vinyl chloride.
Hot Spot 2, located to the south of the farmhouse, yielded high levels of benzene in soil samples,
increasing with depth. Benzene was also detected in the groundwater at concentrations up to
300,000 ug/L.
Hot Spot 3 is a smaller area located to the northwest of the farmhouse and showed high
concentrations of TCE, 1,1,1 -TC A, cis-1,2-DCE, and PCE in the soil.
G. Buried Drums
In 1992 and 1993, EPA removed more than 2500 buried drums from 40 locations in the open
field area at the Boarhead Farms Site. While a significant number of buried drums are believed
to have been removed during this effort, some buried drums still remain. Following completion
of the drum removal action, EPA conducted a magnetometer survey to identify remaining
subsurface magnetic anomalies.
The results of the survey indicated a significant number of magnetic anomalies. Approximately
20 anomalies measured greater than 200 gammas, and most likely represent both fully intact
drums and/or empty crushed drums.
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H. Air
EPA performed air monitoring for health and safety purposes only. Air was monitored at well
heads, in the head space of samples, and in the breathing zone during well installation and
sampling activities. Monitoring was performed using photo ionization detectors (PIDs), flame
ionization detectors (FIDs), combustible gas indicators (CGIs), and oxygen meters. Instrument
readings were recorded in field books documenting each activity. Since most of the
contamination at the Site is subsurface in the soil and groundwater, air was not an evaluated
pathway and is not a concern at the Site.
VII. SUMMARY OF SITE RISKS
Following completion of the Remedial Investigation, EPA conducted analyses to estimate the
human health and environmental hazards that could result if contamination at the Site is not
addressed. These analyses are commonly referred to as risk assessments and identify existing
and future risks that could occur if conditions at the Site do not change. The Baseline Human
Health Risk Assessment (BLRA) evaluated human health risks posed by the Site and the
Ecological Risk Assessment (ERA) evaluated environmental impacts from the Site.
A. Human Health Risks
The BLRA assesses the toxicity, or degree of hazard, posed by contaminants related to the Site
and involves describing the routes by which humans could come into contact with these
substances. Separate calculations are made for those substances that are carcinogenic (cancer
causing) and for those that are non-carcinogenic (but can cause other adverse health effects).
The primary objective of the BLRA was to assess the health risks to individuals who may have
current and future exposure to contamination present at and migrating from the Site under
existing Site conditions. The BLRA is comprised of the following components:
• Identification of Chemicals of Potential Concern (COPCs) - identification and
characterization of the distribution of COPCs found onsite.
• Exposure Assessment - identification of potential pathways of human exposure,
and estimation of the magnitude, frequency, and duration of these exposures.
• Toxicity Assessment - assessment of the potential adverse effects of the COPCs.
• Risk Characterization - characterization of the potential health risks associated
with exposure to Site-related contamination. ,
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Each of these steps is explained further below.
1. Identification of COPCs
The identification of COPCs includes data collection, data evaluation, and data screening steps.
The data collection and evaluation steps involve gathering and reviewing the available Site data
and developing a set of data that is of acceptable quality for risk assessment. This data set is then
further screened to determine those chemicals and media of potential concern. The data used for
the quantitative risk analysis were all validated prior to use in the risk assessment.
Sediment and Surface Water
Samples were collected from the four onsite ponds (PD-8, PD-9, PD-10, and PD-11). In
addition, surface water and sediment samples were collected from Wetland Areas 3 and 12.
Samples from Pond 11 (PD-11) were collected before the pond was drained for drum removal.
Samples of offsite sediment and surface water were collected from the unnamed creek and the
nearby culverts.
Surface Soil
A grid pattern was set up in the open field areas to evaluate surface soil contamination. Samples
were collected from depths of 0 to 6 inches, and subsurface samples were collected from 30 to 36
inches. Each sample was analyzed for target metals and VOCs. Hot spots were determined by
identifying areas with concentrations above EPA Region III Risk Based Concentrations (RBCs)
for residential soil. Shallow soil samples were collected in the wooded wetlands and wooded
uplands areas.
Groundwater
Groundwater beneath the Site is monitored through 35 monitoring wells. Shallow groundwater
in the 29 overburden and upper-diabase wells were considered in the RA. MW-9 and MW-11
were used as background wells. Generally, groundwater around former drum-burial areas marks
the center of the contaminant plumes and wells MW-12, MW-16, MW-20, MW-21, and MW-23
show the highest concentrations of most analytes.
Two residential wells are on the Site - one 150-foot shallow well (RW-10) adjacent to the
farmhouse and one 700-foot deep well (RW-46) associated with Keystone Excavation Building.
The data on RW-10 indicate the presence of site-related contaminants; therefore RW-10 was
included for further analysis in the RA.
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OfFsite residential wells have routinely been sampled since 1989. An analysis of possible human
health risks was performed for the data related to these wells. Granular activated carbon (GAC)
filters have been installed on affected downgradient wells and are monitored regularly.
Background Samples
Nine background soil samples were collected from offsite soil borings and analyzed. Seven of
the samples were collected from the surface (0 to 6 inches) and two were collected from the
subsurface (30 to 36 inches). Background samples of sediment and surface water were collected
from the reference creek (UCOO), reference pond (PDOO), and reference wetlands (WTOO).
Selection of Chemicals of Potential Concern
The COPC selection process was conservative to ensure selection of the most constituents.
Selection of COPCs was based on the criteria presented in EPA Region III guidelines. The
maximum concentration of each detected constituent in each of the media was compared to the
following criteria to select the COPCs for a specific area. If the maximum concentration of a
constituent exceeded each of the criteria, the constituent was selected as a COPC.
• Comparison with Health-Based Criteria: The maximum detected chemical
concentrations in groundwater and soil were compared with EPA Region III risk-
based concentrations (RBCs) which were developed using current toxicity factors
in the exposure formula. These screening level RBCs were based on a target
hazard index of 1.0 and a target cancer risk of 1x10-6. The RBCs for recreational
and residential exposure to surface soil included both inhalation and ingestion
route RBCs. The RBCs for residential groundwater exposure were based on
ingestion of groundwater and inhalation of volatiles from groundwater. The
RBCs for recreational exposure to soil were calculated using exposure factors for
the residential scenario. The RBCs for groundwafe: exposure for a site worker
were also calculated using residential scenario factors, and the RBCs for the soil
exposure scenario for a site worker were calculated by using site worker exposure
factors. Chemicals detected below these Site-specific RBC values were
eliminated from the COPC list.
• Comparison -with Background Samples: The 95 percent upper tolerance limit
(95% UTL) was calculated for each inorganic constituent detected in the set of
background soil, sediment, and surface water samples. For potential source areas
where the maximum detected concentration was greater than the background 95%
UTL (or the maximum background concentration if the 95% UTL is greater than
the maximum), the inorganic constituent was retained as a COPC. For
groundwater, the maximum inorganic-chemical concentrations in the background
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samples were compared with the maximum detected concentrations in the Site
samples, as all inorganic levels in the Site samples were above the background
levels. All inorganics were retained for further analysis in the RA.
• Comparison with Recommended Dietary Allowances (RDAs): Chemicals which
are human nutrients, present at low concentrations (i.e., only slightly elevated
above naturally occurring levels), and toxic only at very high doses were
eliminated from the quantitative risk analysis. These constituents are calcium,
iron, magnesium, potassium, and sodium. All of the human nutrients detected in
groundwater and surface soil were below the RDAs, with the exception of iron
ingestion from groundwater from monitoring wells MW-16, MW-20, MW-21,
MW-12, and MW-23 by children and adults and iron ingestion from open-area
soil by children. However, iron was not selected as a COPC since the RDA was
only slightly exceeded for soil.
Chemicals of Potential Concern
Table 7 identifies the chemicals that were selected as COPCs based on the above screening
methodology for the surface soil, shallow groundwater, pond sediment and pond surface water
areas.
A detailed evaluation of ail chemicals exceeding risk screening criteria is presented hi the
Baseline Risk Assessment of the Remedial Investigation Report.
2. Exposure Assessment
An exposure assessment involves three basic steps: 1) identifying the potentially exposed
populations, both current and future; 2) determining the pathways by which these populations
may be exposed; and 3) quantifying the exposure. Under current Site conditions, the BLRA
identified potential populations as having the potential for exposure to Site-related contaminants,
either currently and/or in the future. The migration pathways for the contamination from the
source areas include volatilization of the VOCs from soil, subsurface soil, and groundwater;
downward migration of the VOCs from soil to the groundwater; lateral downgradient transport of
VOCs in the groundwater; and ingestion of contaminants by aquatic organisms.
Current Land Use
The farmhouse continues to serve as a residence, although the exact number and age of people
living in the house appears to fluctuate with time. The Keystone Excavating Company appears
to be performing some operations in the large garage hi the back of the property. The Site is not
separated from surrounding land and is readily accessible to the public under current conditions.
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Hunters have been observed on the Site and onsite residents use the large ponds for recreational
activities such as swimming and fishing.
Potential Future Uses
The Site is in a rural residential area. EPA expects that future land use in the area will be similar
to present land use. Possible trends include more extensive residential and/or commercial
development. Such activity would potentially expose increased numbers of residents and/or
workers to contaminated areas and might result hi increased use of onsite groundwater. The
ponds, wetlands, and culverts would likely be used by residents and visitors for recreation.
3. Toxicity Assessment
The purpose of the toxicity assessment is to weigh available evidence regarding the potential for
particular contaminants to cause adverse effects in exposed individuals. Where possible, the
assessment provides a quantitative estimate of the relationship between the extent of exposure to
a contaminant and the increased likelihood and/or severity of adverse effects.
A toxicity assessment for contaminants found at a Superfund site is generally accomplished hi
two steps: 1) hazard identification, and 2) dose-response assessment. Hazard identification is
the process of determining whether exposure to an agent can cause an increase in the incidence of
a particular adverse health effect (e.g., cancer or birth defects) and whether the adverse health
effect is likely to occur in humans. Hazard identification further involves characterizing the
nature and strength of the evidence of causation.
Dose-response evaluation is the process of quantitatively evaluating the toxicity information and
characterizing the relationship between the dose of the contaminant administered or received and
the incidence of adverse health effects in the administered population. From this quantitative
dose-response relationship, toxicity values (e.g., reference doses and slope factors) are derived
that can be used to estimate the incidence of or potential for adverse effects as a function of
human exposure to the agent. These toxicity values are used in the risk characterization step to
estimate the likelihood of adverse effects occurring in humans at different exposure levels.
For purposes of the risk assessment, contaminants were classified into two groups — potential
carcinogens and noncarcinogens. The risks posed by these two types of compounds are assessed
differently because noncarcinogens generally exhibit a threshold dose below which no adverse
effects occur, while no such threshold can be proven to exist for carcinogens. As used here, the
term carcinogen means any chemical for which there is sufficient evidence that exposure may
result in continuing uncontrolled cell division (cancer) in humans and/or animals. Conversely,
the term noncarcinogen means any chemical for which the carcinogenic evidence is negative or
insufficient.
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Slope factors have been developed by EPA's Carcinogenic Assessment Group for estimating
excess lifetime cancer risks associated with exposure to potentially carcinogenic contaminants of
concern. Slope factors, which are expressed in units of mg/kg/day are multiplied by the
estimated intake of a potential carcinogen, in mg/kg/day, to provide an upper-bound estimate of
the excess lifetime cancer risk associated with exposure at that intake level. The term "upper-
bound" reflects the conservative estimate of the risks calculated from the slope factor. Use of
this approach makes underestimation of the actual cancer risk highly unlikely. Slope factors are
derived from the results of human epidemiological studies or chronic animal bioassays to which
animal-to-human extrapolation and uncertainty factors have been applied to account for the use
of animal data to predict effects on humans. Slope factors used in the baseline risk assessment
are presented in Table 8.
Reference doses (RfDs) have been developed by EPA for indicating the potential for adverse
health effects from exposure to contaminants of concern exhibiting noncarcinogenic effects.
RfDs, which are expressed in units of mg/kg/day, are estimates of acceptable lifetime daily
exposure levels for humans. Estimated intakes of chemicals from environmental media (e.g, the
amount of a chemical ingested from contaminated drinking water) can be compared to the RfD.
RfDs are derived from human epidemiological studies or animal studies to which uncertainty
factors help ensure that the RfDs will not underestimate the potential for adverse
noncarcinogenic effects to occur. Reference doses used in the baseline risk assessment are
presented in Table 8.
4. Human Health Effects
Toxicological profiles of selected constituents, including TCE, vinyl chloride, 1,1-
Dichloroethene, cis-l,2-Dichloroethene, trans-1,2-Dichloroethene, Tetrachloroethene, 1,1,1-
Trichloroethane, Benzene, 1,2-Dichloropropane, Ethyl Benzene, Toluene, Nitrobenzene, Arsenic,
Aluminum, Antimony, Beryllium, Cadmium, Chromium, Manganese, Nickel, Thallium, and
Zinc can be found in Appendix A.
5. Risk Characterization
The risk characterization process integrates the toxicity and exposure assessments into a
quantitative expression of risk. For carcinogens, the exposure point concentrations and exposure
factors discussed earlier are mathematically combined to generate a chronic daily intake value
that is averaged over a lifetime (i.e., 70 years). This intake value is then multiplied by the
toxicity value for the contaminant (i.e., the slope factor) to generate the incremental probability
of an individual developing cancer over a lifetime as a result of exposure to the contaminant.
The NCP establishes acceptable levels of carcinogenic risk for Superfund Sites ranging from one
excess cancer case per 10,000 people exposed to one excess cancer case per one million people
exposed. This translates to a risk range of between one in 10,000 and one in one million
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additional cancer cases. Expressed as scientific notation, this risk range is between l.OE-04 and
1 .OE-06. Remedial action is warranted at a Site when the calculated cancer risk level exceeds
1 .OE-04. However, since EPA's cleanup goal is generally to reduce the risk to 1 .OE-06 or less,
EPA also may take action where the risk is within the range between 1 .OE-04 and 1 .OE-06.
The potential for noncarcinogenic effects is evaluated by comparing an exposure level over a
specified time period (i.e., the chronic daily intake) with the toxicity of the contaminant for a
similar time period (i.e., the reference dose). The ratio of exposure to toxicity is called a hazard
quotient. A Hazard Index (HI) is generated by adding the appropriate hazard quotients for
contaminants to which a given population may reasonably be exposed. The NCP also states that
sites should not pose a health threat due to a non-carcinogenic, but otherwise hazardous,
chemical. If the HI exceeds one (1.0), there may be concern for the potential non-carcinogenic
health effects associated with exposure to the chemicals. The HI identifies the potential for the
most sensitive individuals to be adversely affected by the noncarcinogenic effects of chemicals.
As a rule, the greater the value of the HI above 1.0, the greater the level of concern.
B. Ecological Risk Assessment
The ecological risk assessment was designed to evaluate the potential threats to ecological
organisms from exposure to Site contaminants and to establish potential Site-specific cleanup
level(s) for the contaminants of concern. The evaluation was made by defining Site
characteristics, potential ecological receptors, contaminants of concern, and pathways potentially
applicable to the ecological resources. The risk characterization is based on complete pathways
and a comparison of concentrations of contaminants at the Site and concentrations associated
with adverse effects. In a screening level assessment, ecological benchmarks fpr contaminants of
concern are derived from the literature and are compared with the onsite concentrations. The
potential for risks within each habitat area were based on an assessment of the environmental
effects quotient (EEQ) for each contaminant and a comparison of the contaminant concentrations
and background levels. The EEQ approach is considered protective of ecological resources since
the onsite contamination levels in the specific medium are compared with literature values on the
basis of the most sensitive receptor for that medium.
Major habitats at the Site include ponds, wooded wetlands, emergent wetlands, wooded uplands,
and open fields. Wildlife observed on and near the Site include a variety of birds, mammals,
reptiles, and amphibians. No state or federally listed threatened or endangered species were
observed on or near the Site.
The analyses in the Ecological Assessment indicated that certain contaminant levels in sediment
and soil at the Site are higher than background levels and ecological criteria. Several
contaminants that occur throughout the Site were identified as COPCs. These COPCs within
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sediment and surface soil appear to pose a potential risk to ecological resources. Concentrations
in the surface water did not appear to pose a significant ecological risk.
In order to better define the Site-specific ecological risk potential, bioassay tests were performed
using Site soils and sediments. The bioassay test for surface soils focused on mortality and
growth of earthworms following a 14-day exposure to the soils. The bioassay test for sediments
focused on mortality and growth of midges (Chironomus tentans) and amphipods (Hyalella
azteca) following a 10-day exposure to the sediments. Surface soil samples were taken from
locations in the upland and forested wetlands. These tests provide information on the direct
toxicity of the soils and sediments to the test organisms and the data can be extrapolated to other
invertebrate species that may inhabit the uplands and wetlands of the Site.
Sediment samples were collected from the onsite ponds and the forested and emergent wetlands.
The survival and rate of growth (both weight and length) of earthworms, amphipods, and midges
were compared to those who were exposed to soils and sediments collected from a reference site.
Statistical analyses indicated that there was no reduction in the survival or growth of organisms
exposed to Site sediments and surface soils. Therefore, the bioassay results indicate that the
presence of contaminants in the surface soil and sediment do not pose a risk to the ecological
resources at the Site.
C. Conclusions
For ingestion, dermal contact, and inhalation of surface soil, surface water, and sediment,
considering both current and future uses, human health risks to Site workers, residents, and
recreational users do not exceed the acceptable limits of 1 to 100 in a million for carcinogenic
risk; nor do they exceed the HI of 1.0 for noncarcinogenic risk.
Risk evaluation for groundwater indicates significant health risks T onsite groundwater is used
for potable purposes. For current and future use, human health ris .s to Site workers, Site
residents, and Site recreational users from shallow groundwater were evaluated for the pathways
of ingestion, dermal contact, and inhalation. These risks exceeded the acceptable limits for
carcinogenic risks as well as the HI for noncarcinogenic risk. VOC and metals contamination in
the shallow groundwater contribute the most to the unacceptable risk levels.
Risk evaluation for offsite groundwater indicates potential health risks significantly above
acceptable levels. Health risks to current residents downgradient from the Site were evaluated
for the pathways of ingestion, dermal contact, and inhalation. Residential risk in 17 of the 26
residential wells evaluated in the residential groundwater exposure assessment present either an
HI greater than 1 or carcinogenic risks greater than 100 in a million. These risks, however, have
been mitigated through the installation of granular activated carbon (GAG) filter systems placed
on the affected residential wells.
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A summary of the human health risks present at the Boarhead Farms Site is presented in Table 9.
For the ecological portion of the BLRA, the analysis indicates that certain background
contaminant levels in sediment and soil within the Site are higher than background levels and
ecological criteria. Several contaminants were identified as ecological contaminants of concern
(COCs) and could pose a potential risk to ecological resources. Site specific bioassay results
were performed on surface soil and sediment samples. The bioassay results indicate that the
presence of contaminants in the surface soil and sediments do not pose a risk of harm to
ecological resources at the Boarhead Farms Site.
VIIL DESCRIPTION OF REMEDIAL ALTERNATIVES CONSIDERED FOR THE
SITE
The Feasibility Study (FS) identified a series of alternatives to address the subsurface soil and
groundwater at the Boarhead Farms Site. Six alternatives were identified as possible response
actions. These alternatives, described below, are numbered to correspond with alternatives found
in the FS. For a summary of the alternatives, see Table 10.
Alternative 1: • No Action
Capital Cost SO
Total Present Worth Cost $0
Operation & Maintenance (O&M)(30 yr) SO/yr
The NCP requires that EPA consider a "No Action" alternative for every Superfund Site to
establish a baseline or reference point against which each of the remedial action alternatives are
compared. Under the "No Action" alternative, the current groundwater treatment system, which
is.currently being funded by EPA as a removal response action, would be shut down and no
further monitoring or maintenance would take place onsite nor at the surrounding affected
residential wells. All current and potential future risks would remain.
Alternative 2: Continued Maintenance and Monitoring of the Existing Groundwater
Interceptor Trench, Treatment Facility, and Residential Well GAC
Filters; Institutional Controls
Capital Cost $960,000
Total Present Worth Cost $3,000,000
Operation & Maintenance (O&M)(30 yr) $130,000/yr
Under this alternative, the existing interceptor trench and groundwater treatment facility would
continue to be operated and maintained. No other remediation would take place on the Site. The
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cost for this alternative includes amounts required to maintain the existing interceptor trench,
groundwater treatment facility, and carbon filters previously installed on selected residential'
wells. Institutional controls would be added to protect the integrity of the interceptor trench by
restricting construction, excavation, regrading, and other activities in the area near the trench.
Since hazardous substances would be left onsite, a review of Site conditions would be required
no less often than every five years pursuant to Section 121 (c) of CERCLA, 42 U.S.C. § 9621(c).
Alternative 3: Soil Excavation, Multilayer Cap; Excavation and Offsite Disposal of
Buried Drums; Groundwater Extraction, Metals Precipitation, and
Air Stripping; Institutional Controls and Monitoring; and Residential
Water Treatment
Capital Cost ' $5,200,000
Total Present Worth Cost $11,690,000
Operation &Maintenance (O&M)(30 yr) $420,000/yr
This alternative combines the excavation of contaminated soil and buried drums with offsite
disposal and capping of the contaminated central area (Areas 5 and 6). All contaminated soils,
the aerial extent of which is approximated in Figure 5, would be excavated down to a level where
all contaminants of potential concern (COPCs) are below the risk-based concentrations (RBCs)
identified in the risk assessment for the Boarhead Farms Site. These soils would be tested to
determine whether they exhibit hazardous characteristics in accordance with RCRA, treated as
required, and placed in a central area where a geomembrane cap would be constructed to prevent
discharge of contaminants into the groundwater. The cap would be surrounded by perimeter
fencing to restrict access to contaminated materials and to protect the cap. If excavation is
necessary in wetland areas, actions would be taken to avoid impacts to such wetlands, minimize
wetlands destruction, and preserve and enhance the value of the wetlands as required by 40
C.F.R. Part 6, Appendix A.
Anomalies identified during the magnetometer survey conducted in the Remedial Investigation
phase would be investigated and all buried intact and crushed drums would be excavated. The
drums and surrounding soils would be disposed of offsite. Soils would be tested for hazardous
characteristics and handled in accordance with RCRA, including Land Disposal Restriction
treatment requirements. EPA suspects that a portion of the buried drums are located beneath the
garage of the onsite residence. Should EPA confirm that anomalies exist beneath the garage,
partial demolition of the garage may be necessary.
The groundwater treatment facility would be augmented by adding a metals precipitation unit as
well as a vapor-phase carbon unit for off-gas treatment. The metals precipitation unit would
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remove the metal contaminants from the groundwater while the VOCs continue to be removed
by the air stripping unit. These additions would satisfy Clean Water Act effluent discharge
requirements and Clean Air Act air emission limits for organic and inorganic pollutants. The
treated groundwater would be discharged to the wetland area adjacent to the treatment building.
Carbon filters previously placed on affected residential wells would continue to be maintained
and the well water would continue to be monitored to be sure contaminated groundwater from
the Site is not reaching the wells. MCLs for the relevant contaminants would be met at
residential wells. Institutional controls would be implemented to protect the integrity of the cap
and the existing groundwater treatment system. An operation and maintenance program to
maintain the groundwater treatment system, cap, and GAC filters installed at impacted residences
would be implemented. Since hazardous substances would be left onsite, a review of Site
conditions would be required no less often than every five years pursuant to Section 121(c) of
CERCLA, 42 U.S.C. § 962l(c).
Alternative 4: Soil Excavation and Stabilization/Solidification; Excavation and
Offsite Disposal of Buried Drums; Groundwater Extraction, Metals
Precipitation, and UV Oxidation; Institutional Controls and
Monitoring; and Residential Water Treatment
Capital Cost $10,770,000
Total Present Worth Cost $21,580,000
Operation & Maintenance (O&M)(30 yr) $700,000/yr
This alternative combines stabilization/solidification (S/S) of contaminated soils, offsite disposal
of buried drums, groundwater extraction, metals precipitation, and UV Oxidation with the
institutional controls and monitoring and residential water treatment described in Alternative 2.
In situ S/S of the contaminated overburden soil from the top of the test pit areas to the top of the
bedrock would occur. Approximately 32,700 cubic yards (cy) of soil would be stabilized using
equipment capable of injecting stabilization reagents and mixing the soil below the ground
surface. Ex situ S/S of contaminated subsurface and surface soil from the wetlands, uplands, and
the farmhouse area would also occur. Contaminated soils (approximate locations shown of
Figure 5) would be excavated down to a level where all contaminants of potential concern
(COPCs) are below the risk-based concentrations (RBCs) identified hi the risk assessment for the
Boarhead Farms Site. These soils would be tested to determine whether they exhibit hazardous
characteristics in accordance with RCRA, treated as required, moved to a central area, and
stabilized ex situ using a transportable stabilization plant. Before stabilization, soil would be
stockpiled on a liner to prevent contamination from leaching into the underlying stabilized soil.
Stabilized soil would be placed hi the test pit area and covered with 18 inches of clean soil to
provide a buffer. Clean soil would be used to cover the stabilized soil as well as to backfill the
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excavated areas. If excavation is necessary in wetland areas, actions would be taken to avoid
adverse impacts to such wetlands, minimize wetlands destruction, and preserve and enhance the
value of the wetlands to the extent required by 40 C.F.R. Part 6, Appendix A.
The existing groundwater treatment facility would be modified by replacing the current air
stripper with a UV oxidation unit and adding a metals precipitation unit. The remaining buried
drums would be excavated and disposed of offsite as in the alternatives above.
Institutional controls would be added to protect the stabilized materials from being disturbed.
Such controls will prohibit excavation and regrading in the areas where stabilization has
occurred. An O&M program to maintain the groundwater treatment system and residential GAC
filters would be implemented. Since hazardous substances would be left onsite, a review of Site
conditions would be required no less often than every five years pursuant to Section 121(c) of
CERCLA, 42 U.S.C. § 9621(c).
Alternative 5: Excavation of Soil and Placement in Onsite Landfill; Excavation and
Offsite Disposal of Buried Drums; Groundwater Extraction, Metals
Precipitation, and Air Stripping; Institutional Controls and
Monitoring; and Residential Water Treatment
Capital Cost $6,890,000
Total Present Worth Cost $13,090,000
Operation & Maintenance (O&M)(30 yr) $400,000/yr
This alternative combines the construction of an onsite landfill with the drum excavation and
offsite disposal, groundwater extraction, metals precipitation, air stripping, institutional controls
and monitoring, and residential well treatment described in the above alternatives.
The newly constructed landfill would be positioned in the central area. Outlying contaminated
soils (see Figure 5 for an approximation of location and extent; the actual extent of excavation
would be determined during remedial design) as well as the soils in the central area would be
excavated down to levels where all contaminants of potential concern (COPCs) are below the
risk-based concentrations (RBCs) identified in the risk assessment for the Boarhead Farms Site.
These soils would be tested to determine whether they exhibit hazardous characteristics in
accordance with RCRA, treated as required, and placed into the landfill. The landfill lining
system would include a leachate collection system, double lining, and a leak detection system.
Approximately 65,400 cubic yards (cy) of capacity would be required. Leachate collected from
the cell would be treated at the onsite groundwater treatment plant. The landfill would be capped
with a multilayer RCRA cap and a security fence installed. If excavation is necessary in wetland
areas, actions would be taken to avoid adverse impacts to such wetlands, minimize wetlands
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destruction, and preserve and enhance the value of the wetlands to the extent required by 40
C.F.R. Part 6, Appendix A.
Institutional controls would be implemented to protect the integrity of the landfill and the
groundwater treatment system. In addition, a fence would be constructed around the landfill to
ensure protection from trespassers. An O&M program to maintain the landfill, groundwater
treatment facility, residential GAC filters, and fence would be implemented. Since hazardous
substances would be left onsite, a review of Site conditions would be required no less often than
every five years pursuant to Section 121 (c) CERCLA, 42 U.S.C. § 9621(c).
Alternative 6: Soil Aeration and Treatment of VOC Hot Spots; Excavation and
Offsite Disposal of Buried Drums; Groundwater Extraction, Metals
Precipitation, and Air Stripping; Institutional Controls and
Monitoring; and Residential Water Treatment
Capital Cost $7,180,100
Total Present Worth Cost $13,157,000
Operation & Maintenance (O& M)(30 yr) $463,900/yr
This alternative uses aeration of soil hot spots contaminated with high concentrations of VOCs in
combination with the offsite disposal of buried drums, groundwater extraction, metals
precipitation, air stripping, institutional controls and monitoring, and residential water treatment
as described in the above alternatives.
The soils from two hot spot areas identified during the RI/FS would be collected and
mechanically aerated in a temporary containment building constructed onsite to remove the VOC
contaminants. The building would be equipped with dust and carbon filtration units for air
treatment. The off-gas treatment would be designed to meet air e; lissions ARARs. The water
that refills the excavated TCE area would be pumped to the existi: g treatment system or air
sparged. The clean soils would be used as fill for the excavated areas. Since excavation would
be necessary in wetland areas, actions would be taken to avoid adverse impacts to such wetlands,
minimize wetlands destruction, and preserve and enhance the value of the wetlands to the extent
required by 40 C.F.R. Part 6, Appendix A.
Carbon filters previously placed on affected residential wells would continue to be maintained
and the residential well water would continue to be monitored to be sure contaminated
groundwater from the Site is not reaching the wells. An O&M program to maintain the soil
aeration/treatment system, the groundwater treatment facility, and residential GAC filters would
be implemented. Since hazardous substances would be left onsite, a review of Site conditions
would be required no less often than every five years pursuant to Section 121 (c) of CERCLA, 42
U.S.C. § 9621 (c).
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IX. COMPARATIVE EVALUATION OF ALTERNATIVES
Each of the remedial alternatives summarized in this ROD has been evaluated against the nine
evaluation criteria set forth in the NCP (see 40 C.F.R. Section 300.430(e)(9)). These nine criteria
can be categorized into three groups — threshold criteria, primary balancing criteria, and
modifying criteria. A description of the evaluation criteria is presented below:
Threshold Criteria:
1. Overall Protection of Human Health and the Environment addresses whether a remedy
provides adequate protection and describes how risks are eliminated, reduced, or
controlled.
2. Compliance with Applicable or Relevant and Appropriate Requirements (ARARs)
addresses whether a remedy will meet all of the applicable, or relevant and appropriate
requirements of federal environmental laws, as well as state environmental or facility
siting laws.
Primary Balancing Criteria:
3.
are achieved.
Long-term Effectiveness and Permanence refers to the ability of a remedy to maintain
reliable protection of human health and the environment over tune once clean up levels
are achieved.
4. Reduction of Toxicity, Mobility, or Volume through Treatment addresses the degree to
which alternatives employ recycling or treatment that reduces toxicity, mobility, or
volume of contaminants.
5. Short-term Effectiveness addresses the period of time needed to achieve protection and
any adverse impacts on human health and the environment that may be posed during
implementation of the alternative.
6. Implementability addresses the technical and administrative feasibility of a remedy,
including the availability of materials and services needed to implement that remedy.
7. Cost refers to an evaluation of several categories of costs associated with a particular
alternative. The cost categories include capital costs, including direct and indirect costs;
annual operation and maintenance costs; and net present value of capital and O&M costs.
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Modifying Criteria;
8. State Acceptance indicates whether the State concurs with, opposes, or has no comment
on EPA's preferred alternative.
9. Community Acceptance assesses public reaction - evidenced by public comment on the
Administrative Record file and the Proposed Plan - to each of the alternatives considered
for the Site.
*• Overall Protection of Human Health and th
A primary requirement of CERCLA is that the selected remedial alternative be protective of
human health and the environment. A remedy is protective if it reduces current and potential
risks to acceptable levels under the established risk range posed by each exposure pathway at the
Site.
Alternative 1 would not protect human health and the environment as unacceptably high risks
discussed in Section VII (Summary of Site Risks) would remain at the Site. Accordingly, this
alternative will not be further analyzed in this ROD.
Although VOCs in the groundwater are treated hi Alternative 2, system capacity is likely
inadequate, air emissions are generated, inorganics are not reduced, and contaminants will
migrate offsite. In addition, under Alternative 2 no soil contamination would be addressed and
the contaminants in the soil hot spots would continue to leach into the groundwater. MCLs for
the residential water supply would be met. Alternative 2 as a whole would not adequately
protect human health and the environment since unacceptably high risks discussed in Section VII
(Summary of Site Risks) would remain at the Site. Accordingly, this alternative will not be
further analyzed in this ROD.
Alternatives 3, 4, 5, and 6 are all protective of human health and the environment. All four
alternatives provide for an upgrade of the existing groundwater treatment facility with the
addition of a metals precipitation unit and methods for further treatment of VOCs. Each of the
four alternatives also reduces the risk of exposure to contaminated soils. Under Alternative 3 the
wastes remain onsite, but installation of the cap will minimize infiltration and leaching through
the contaminated soil above the groundwater table. Under Alternative 4, soil stabilization and
solidification would occur, preventing further leaching altogether. Alternative 5 would protect
human health and the environment by containing the contaminated soils and hot spots in an
onsite landfill. The landfill would be constructed in a manner that would minimize infiltration
and leaching. Access to contaminated soils would thus be significantly reduced once the soils
were placed in the landfill. Alternative 6 is protective through largely eliminating organic
contaminants from the hot spot areas, in turn reducing the possibility of the organics leaching
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into the groundwater. With the inclusion of institutional controls, monitoring, and continued
excavation and removal of buried drums, each of the Alternatives 3,4,5, and 6 would reduce the
possibility of further exposure to contaminated soils and further consumption of contaminated
groundwater.
2. Compliance with Applicable or Relevant and Appropriate Requirements (ARARs^
Any cleanup alternative considered by EPA must comply with all applicable or relevant and
appropriate federal and state environmental requirements. Applicable requirements are those
substantive environmental standards, requirements, criteria, or limitations promulgated under
federal or state law that are legally applicable to the remedial action to be implemented at the
Site. Relevant and appropriate requirements, while not being directly applicable, address
problems or situations sufficiently similar to those encountered at the Site that their use is well-
suited to the particular Site.
Chemical-Specific ARARs
Alternatives 3,4,5, and 6 would satisfy treatment effluent discharge requirements and air
emission limits for organic and inorganic pollutants. Alternatives 2 through 6 would also meet
MCL levels at residential wells. Alternative 1 would not meet these requirements.
Action-Specific ARARs
Alternatives 3 and 5 would meet the substantive requirements of any required Resource
Conservation and Recovery Act (RCRA) treatment, storage and disposal (TSD) ARARS such as
design, operation, closure, and post-closure of a RCRA landfill.
Alternatives 3 and 4 would meet RCRA hazardous waste ARARs triggered by excavation of
contaminated soils including storage time limits, manifesting, and transporting requirements.
Alternatives 3 and 5 may require that the Site be designated a corrective action management unit
(CAMU) to avoid invoking RCRA's land disposal restrictions (LDRs).
Treatment of inorganics in onsite groundwater (Alternatives 3 through 6) and treatment of off-
gas (Alternatives 3, 5, and 6) will require offsite disposal, proper manifesting, and tracking to
ensure that waste arrives at a permitted facility.
Location-Specific ARARs
If wetlands are disturbed in Alternatives 3,4, 5, and 6 actions will be taken to avoid adverse
impacts to such wetlands, minimize wetlands destruction, and preserve and enhance the value of
the wetlands, to the extent required by 40 CFR Part 6, Appendix A.
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3. Long-Term Effectiveness and Permanence
Magnitude of Residual Risk
Alternative 4 would provide more expedient control of residual risk since the soil contamination
would be immediately stabilized to minimize leaching. Alternative 3, which provides a cap over
the central area, would allow contaminants underneath the cap to desorb into the groundwater
and leave residual contamination in the soil above the water table. Alternative 5 would reduce
the risk of exposure to residual contaminants since such contaminants would be encapsulated in
the onsite landfill. Alternative 6 would reduce residual risk in the hot spot areas since the soil
would be removed and treated, thus minimizing leaching. O&M of the landfill and groundwater
treatment system and institutional controls provided for in Alternatives 3,4, 5, and 6 would
reduce the risk of migration and risk of exposure from residual contamination.
Adequacy and Reliability of Controls
Alternatives 3,4,5, and 6 offer equally reliable groundwater treatment processes capable of
removing contaminants from the groundwater intercepted by the downgradient trench. For
contaminated soils, Alternative 3 can reliably minimize surface water infiltration and resulting
contaminant desorption. Alternatives 4 and 5, using soil solidification/stabilization and
landfilling can reliably prevent leaching effects and provide groundwater protection. Although
stabilization technology works well with certain types of wastes, particularly heavy metals,
recent literature on the effectiveness of stabilization on VOC-contaminated soils shows that this
approach is not always effective and VOCs continue to leach from the stabilized areas.
Therefore, while stabilization has been shown to be protective with respect to metals-
contaminated soils, EPA concludes that this technology may not be as protective of the
community with respect to the VOC contamination. Alternative 6, soil aeration, can reliably
remove VOCs from the hot spot areas.
4. Reduction of Toxicity. Mobility, or Volume through Treatment
Toxicity and volume reduction are not fully achieved by capping in Alternative 3 since the
contaminants hi the soil would not be fully isolated. The contaminants would still leach into the
groundwater over time until reaching the trench system or extractions wells. A slight reduction
in mobility would eventually occur, however, since downward infiltration of groundwater would
decrease. Alternative 4 generates less waste through organic treatment than Alternatives 3, 5,
and 6 since carbon filters are not used in the treatment system. Alternative 6 would reduce the
volume and toxicity of organic contaminants in select hot spots only.
Alternatives 3 through 6 would aid in reducing toxicity if the existing onsite treatment facility is
maintained properly.
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5. Short-Term Effectiveness
Alternatives 3,4, 5, and 6 are equally effective in the short-term, but present various risks of
exposure during construction since contaminated soil is excavated.
6. Implementability
Each of the alternatives is technically implementable. Alternatives 3,4, 5, and 6 require
treatability studies and/or specialty contractors for items such as capping, stabilization, and soil
aeration.
Since UV oxidation in Alternative 4 does not generate air emissions, installation of carbon filter
units and associated maintenance is not required. Alternative 4 requires more effort to
implement than the other alternatives due to the volume of soil that is excavated, treated
chemically, and relocated. Design, construction, and operation of the landfill (Alternative 5)
requires a high level of effort to implement and requires long-term O&M.
7. Cost
Evaluation of the costs of each alternative generally includes calculation of direct and indirect
capital costs and the annual operation and maintenance (O&M) costs, both calculated on a
present worth basis. The total present worth cost of all Alternatives has been calculated for
comparative purposes and is presented below.
Alternative
1
2
3
4
5
6
Total Present Worth Cost
$0
$3,000,000
$11,690,000
$21,580,000
$13,090,000
$13,157,000
Direct capital costs include costs of construction, equipment, building and services, and waste
disposal. Indirect capital costs include engineering expenses, start-up and shutdown, and
contingency allowances. Annual O&M costs include labor and material; chemicals, energy, and
fuel; administrative costs and purchased services; monitoring costs; cost for periodic site review
29
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(every five years); and insurance, taxes, and license costs. For cost estimation purposes, a period
of 30 years has been used for O&M. In reality, maintenance of a multilayer cap on a landfill
would be expected to continue beyond this period. Similarly, the actual duration of operation for
the groundwater extraction and treatment system would depend on the system's ability to
successfully limit offsite migration of Site-related contaminants.
8. State Acceptance
The Commonwealth of Pennsylvania has concurred with the selected remedy.
9. Community Acceptance
A public meeting on the Proposed Plan was held on January 14,1998 at the Palisades High
School, Kintnersville, Pennsylvania. Comments received orally at the public meeting and in
writing during the comment period are presented and addressed in the Responsiveness Summary,
Part III of this ROD.
X. SELECTED REMEDY AND PERFORMANCE STANDARDS
Following consideration of the requirements of CERCLA, a detailed analysis of the alternatives
using the nine criteria set forth hi the NCP, and careful review of public comments, EPA has
selected Alternative 6 for implementation at the Boarhead Farms Site. The following are the key
components of the selected remedy:
A. Soil Aeration and Treatment of VOC Hot Spots: Two areas were identified during the
FS that contain high levels of VOCs and are outside the reach of the existing collection
trench system. The first is located west of the Site residence and south of the Keystone
garage. Soils in this area contain high levels of benzene. The area is along a small weed-
overgrown road leading from the Keystone garage area toward the Pennsylvania game
lands. Soils with benzene levels in excess of 0.5 ppm (the statewide soil-to-groundwater
standard for benzene established under Pennsylvania's Land Recycling and
Environmental Remediation Standards Act (35 P.S.§§ 6026.101-6026.909) and
implementing regulation) shall be excavated from this area such that the benzene
concentrations in the bottom and side walls of the excavation do not exceed 0.5 ppm.
The second VOC hot spot area is approximately 1/4 mile from the residence along and
including a small road leading north from the main site access road. This area contains
high levels of TCE. Soils with TCE in excess of 0.4 ppm (EPA's risk-based cleanup
level developed in the risk assessment) will be excavated such that TCE concentrations in
the bottom and side walls of the excavation do not exceed 0.4 ppm TCE. EPA estimates
that there are approximately 2,000 cubic yards (cy) of contaminated soils in the benzene
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contaminated area and 10,000 cy in the TCE - contaminated area that will need to be
excavated. The wooded wetlands shall be left undisturbed.
Excavated soils shall be relocated to an onsite facility (to be constructed) where the
VOCs will be stripped from the soils. Air stripping will occur via mechanical aeration
down to levels of 0.5 ppm for benzene (the statewide soil-to-groundwater standard for
benzene established under Pennsylvania's Land Recycling and Environmental
Remediation Standards Act (35 P.S.§§ 6026.101-6026.909) and implementing regulation)
and 0.4 ppm for TCE (EPA's risk-based cleanup level developed in the risk assessment).
Treatment will involve construction of a temporary onsite treatment building equipped
with carbon filters to ensure that air quality criteria are maintained. Clean soils will be
returned to the areas of excavation.
B. Excavation and Offsite Disposal of Buried Drums: All metal anomaly areas identified
in the RI shall be excavated down to the bedrock in order to find buried drums. A drum
is any container which could contain five or more gallons. Upon drum encounter the
buried drum and all soils in intimate contact with the drum shall be excavated and
overpacked for offsite disposal. Soils in intimate contact with drums are soils within
eighteen inches of the surfaces of such drums or, where visible contamination is present,
all visibly stained soils. Care will be taken not to allow drum contents to spill on to the
ground. If spillage occurs, the spillage area along with 18 inches of soil around the spill
area will be excavated and overpacked for offsite disposal. Drum contents and related
excavated soils will be characterized in accordance with RCRA characterization
protocols, treated as required, and disposed of to reduce the potential for continued
migration of contaminants to the soil and groundwater as well as to reduce the risk of
exposure.
C. Groundwater Extraction, Metals Precipitation, and Air Stripping: Groundwater will
be collected and extracted using the existing interceptor trench and extraction wells and
treated using air stripping (for VOCs) and metal precipitation (for metals) systems.
Treatment of extracted groundwater shall continue until MCLs or the non-zero Maximum
Contaminant Level Goals (MCLGs) for groundwater are met at the interceptor trench for
eight (8) consecutive quarters (see detailed requirements #6, below). Any surface water
discharge will comply with the substantive requirements of the Clean Water Act NPDES
regulations (40 C.F.R. §§ 122.41-122.50), the Pennsylvania NPDES regulations (25 Pa
Code § 92.31), the Pennsylvania Wastewater Treatment regulations (25 Pa Code §§ 95.1-
95.3), and the Pennsylvania Water Quality Standards (25 Pa Code §§ 93.1-93.9). Air
emissions from this system must comply with the requirements of the Clean Air Act.
D. Institutional Controls and Monitoring: Institutional controls to protect the integrity of
the interceptor trench, groundwater treatment system, soil aeration treatment area, and
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phytoremediation area will be implemented and will remain in effect as long as is
necessary to achieve the Performance Standards. Institutional controls will also be
implemented to protect the previously installed soil cover (the areal extent of which is
between and among the test pits approximated in Figure 4) and will remain in effect as
long as necessary to prevent exposure to contaminated subsoils. Site wells and selected
residential drinking water wells will be monitored to evaluate the effectiveness of the
remedy as provided in paragraph 8, below.
E. Installation of Additional Monitoring Wells: Additional monitoring wells will be
installed to monitor the migration of contaminants in the shallow and intermediate
groundwater zones, as well as to monitor the effectiveness of the remedial action. A
minimum of two additional wells shall be installed along Lonely Cottage Road, with one
across from the Sportsman's Club. The total number and location of other additional
monitoring wells will be determined during remedial design.
F. Residential Water Treatment: The granular activated carbon (GAC) filters that were
installed on affected residential water wells in the surrounding area to prevent exposure to
contaminated groundwater from the Site shall be maintained. GAC units will be replaced
as needed based on their performance as determined by the long-term monitoring
program to ensure the health and safety of the residents. Used filters shall be disposed of
in accordance with State and Federal laws. Monitoring of the affected residential wells
will occur until EPA determines that the Performance Standard for each contaminant of
concern has been achieved for all residences with wells equipped with GAC filters
installed during the removal action; the wells shall be sampled semiannually for three
years after the Performance Standard is met for all affected wells, and if contaminants
remain at or below the Performance Standards, the GAC filters shall be removed and
properly disposed.
*
G. Phytoremediation: A treatability study will be performed to determine whether or not
phytoremediation will aid in uptake of the contaminants at the Site. The specific type and
location of the plants used in the process will be determined in the design of the
treatability study. In addition, during the study the parameters to identify whether or not
the phytoremediation process is removing enough contaminants from the soil and
groundwater to be of use to the remediation process will be determined. EPA will
determine, based on the results of the treatability study, whether phytoremediation will be
implemented at the Site. The plants will be used to augment the efficiency of the
interceptor treatment system on a long-term basis. Plants will be maintained and replaced
as needed. The specific type and placement of these plants will be determined in the
treatability study.
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Further detailed requirements and Performance Standards associated with the selected remedy
are presented below.
1. Excavated soils, drums, spent filter media and spent filters shall be tested to determine
the presence of RCRA characteristic wastes. All RCRA characteristic wastes shall be
handled in accordance with the substantive requirements of 25 Pa. Code Chapter 262
Subchapters A (relating to hazardous waste determination and identification numbers); B
(relating to manifesting requirements for offsite shipments of hazardous wastes); and C
(relating to pretransport requirements); 25 Pa. Code Chapter 263 (relating to transporters
of hazardous wastes); and with respect to the operations at the Site generally, with the
substantive requirements of 25 Pa. Code Chapter 264, Subchapters B-D, I (in the event
that hazardous waste generated as part of the remedy is managed in containers); 25 Pa.
Code Chapter 264, Subchapter J (in the event that hazardous waste is managed, treated,
or stored in tanks), and 40 C.F.R. Part 268, Subpart C and Subpart E (regarding
prohibitions on land disposal and prohibitions on storage of hazardous waste).
2. All areas impacted by the construction activities during remedy implementation shall be
graded, restored and revegetated to the extent practicable.
3. Wastewater generated during decontamination activities shall be properly managed in
accordance with State and Federal Laws.
4. Fugitive dust emissions generated during remedial activities will be controlled in order to
comply with fugitive dust regulations in the federally-approved State Implementation
Plan (SIP) for the Commonwealth of Pennsylvania, 25 Pa. Code §§ 123.1 - 123.2 and the
National Ambient Air Quality Standards for Paniculate Matter in 40 C.F.R. § 50.6 and
Pa. Code §§131.2 and 131.3.
5. Drum Excavation and Removal - All areas identified in the remedial investigation where
buried metal anomalies (such as buried drums) were detected will be excavated and
investigated. All drums found containing any material will be overpacked, staged, RCRA
categorized, treated (if required by RCRA) and shipped offsite for disposal. Soils in
intimate contact with these drums will be excavated, treated (if required by RCRA), and
disposed. Soils in intimate contact with drums are soils within eighteen inches of the
surfaces of such drums or, where visible contamination is present, all visibly stained
soils. Management of drum waste from these excavated areas shall comply with the
requirements of 25 Pa. Code Chapter 262 Subchapters A (relating to hazardous waste
determination and identification numbers); B (relating to manifesting requirements for
offsite shipments of hazardous wastes); and C (relating to pretransport requirements); 25
Pa. Code Chapter 263 (relating to transporters of hazardous wastes); and with respect to
the operations at the Site generally, with the substantive requirements of 25 Pa. Code
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Chapter 264, Subchapters B-D, I (in the event that hazardous waste generated as part of
the remedy is managed in containers); 25 Pa. Code Chapter 264, Subchapter J (in the
event that hazardous waste is managed, treated or stored in tanks); and 40 C.F.R. Part 268
Subpart C, Section 268.30, and Subpart E (regarding prohibitions on land disposal and
prohibitions on storage of hazardous waste).
6. Groundwater Treatment - A) The groundwater at the interceptor trench shall be extracted
and treated hi the onsite treatment facility until the MCLs, health advisory levels, or risk-
based ingestion or inhalation numeric values set forth under Pennsylvania Act 2 standards
(35 P.S. §§ 6026.101 - 6026.909) for all contaminants of concern are achieved for eight
(8) consecutive quarters of sampling. The Performance Standards for the contaminants in
the groundwater are listed below:
Contaminant MCLteS/D _ Health Advisory Inhalation
Arsenic 50
Beryllium 4
Cadmium 5
Chromium (Total) 100
Zinc 2,000
Benzene 5
Trichloroethene (TCE) 5
l,l-Dichloroethene(l,l-DCE) 7
Xylenes 10,000
Lead 5
Nickel 100
l,l-Dichloroethane(l,l-DCA) 27
Cis - 1,2-Dichloroethene 70
Ethylbenzene 700
Tetrachlroethene(PCE) 5
1,1,1-Trichloroethane 200
B) Recovered groundwater shall be treated to remove VOCs and metals and discharged
in accordance with the substantive requirements of the Clean Water Act NPDES
discharge regulations (40 C.F.R. §§ 122.41-122.50), the Pennsylvania NPDES
regulations (25 Pa Code § 92.31), the Pennsylvania Wastewater Treatment regulations
(25 Pa Code §§ 95.1-95.3), and the Pennsylvania Water Quality Standards (25 Pa Code
§§ 93.1-93.9). The treatment system shall reduce the contaminants in the extracted
groundwater, unattended, on a continuous, 24-hour-per-day basis. The final pumping rate
of the extraction wells shall be determined during remedial design. Final design criteria
34
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for the air stripper and metals precipitation treatment systems will be determined in the
Remedial Design phase.
C) Any VOC emissions from treatment of groundwater, including air stripping and/or air
sparging, will be in accordance with the Pennsylvania air pollution regulations outlined in
25 Pa. Code §§ 121.1 - 121.3,121.7,123.1, 123.2, 123.31, 123.41, 127.1, 127.11, 127.12,
and 131.1-131.4. 25 Pa. Code § 127.12 requires all new air emission sources to achieve
minimum attainable emissions using the best available technology (BAT). In addition,
the PADEP air permitting requirements for remediation projects require all air stripping
and vapor extraction units to include emission control equipment. Federal Clean Air Act
requirements, 42 U.S.C. §§ 7401 fit seq.. are applicable and must be met for the discharge
of contaminants to the air. Air permitting and emissions requirements are outlined in 40
C.F.R. §§264.1030 - 264.1034 (Air Emissions Standards for Process Vents), and 40
C.F.R. §§ 264.1050 - 264.1063 (Air Emissions Standards for Equipment Leaks).
OSWER Directive #9355.0-28, Control of Air Emissions from Superfund Air Strippers at
Superfund Ground Water Sites, is a "to be considered" (TBC) requirement.
D) Management of waste from the operation of the treatment system (i.e. spent carbon
units, flocculates) shall comply with the requirements of 25 Pa. Code Chapter 262
Subchapters A (relating to hazardous waste determination and identification numbers); B
(relating to manifesting requirements for offsite shipments of hazardous wastes); and C
(relating to pretransport requirements); 25 Pa. Code Chapter 263 (relating to transporters
of hazardous wastes); and with respect to the operations at the Site generally, with the
substantive requirements of 25 Pa. Code Chapter 264, Subchapters B-D, I (in the event
that hazardous waste generated as part of the remedy is managed in containers); 25 Pa.
Code Chapter 264, Subchapter J (in the event that hazardous waste is managed, treated or
stored in tanks); and 40 C.F.R. Part 268 Subchapter C, Section 268.30, and Subchapter E
(regarding prohibitions on land disposal and prohibitions on storage of hazardous waste).
7. The extraction and treatment system shall avoid, minimize, and mitigate impacts on the
area wetlands in compliance with Executive Order No. 11990 and 40 C.F.R. Part 6,
Appendix A (regarding avoidance, minimization, and mitigation of impacts on wetlands).
8. Maintenance and Monitoring
A) The soil aeration equipment, groundwater extraction and treatment system, residential
water treatment systems, phytoremediation areas, Site monitoring wells, previously
installed soil cover, and all other remedial action components shall be operated and
maintained in accordance with an Operation and Maintenance plan to be developed for
this remedial action. The Operation and Maintenance plan shall ensure that all remedial
action components operate within design specifications and are maintained in a manner
that will achieve the Performance Standards. The Operation and Maintenance plan shall
be updated from time-to-time as may be necessary to address additions and changes to the
remedial action components (e.g., following metals-treatment upgrades to the water
treatment plant).
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B) A long-term groundwater monitoring program shall be implemented to evaluate the
effectiveness of the interceptor trench, treatment system, and other remedial action
components in reducing contamination in the groundwater to achieve the Performance
Standards. The long-term groundwater monitoring program will provide for the
sampling and analysis of groundwater from Site monitoring and selected residential
drinking wells, the maintenance of Site monitoring wells, and for, among other things, the
following:
(i) The installation of additional monitoring wells may be required to monitor the
migration of contaminants in the shallow and intermediate groundwater zones.
Numbers and locations of these monitoring wells shall be determined (as needed)
by EPA during the remedial design, in consultation with PADEP.
(ii) The monitoring and residential drinking water wells shall be sampled at least
three times a year for the first three years. Based on the findings of the first three
years of sampling, the appropriate sampling frequency for subsequent years will
be determined by EPA, in consultation with PADEP.
(iii) The influent and effluent from the treatment facility shall be sampled a
minimum of once per month and analyzed for each contaminant for which a
Performance Standard has been provided hi Paragraph 6A.
(iv) Sampling from and operation/maintenance of the monitoring wells and
groundwater extraction/treatment system shall continue until such time when
EPA, in consultation with PADEP, determines that groundwater treatment is no
longer necessary as set forth herein.
(a) EPA, in consultation with PADEP, shall determine whether the
Performance Standard for each contaminant for which a Performance
Standard has been provided in Paragraph 6A, above, has been achieved
throughout the entire area of groundwater contamination. Following any
such determination, the monitoring wells shall continue be sampled for
eight (8) consecutive quarters (the "Confirmation Period").
(b) If any Paragraph 6A contaminant is detected in groundwater at a
concentration above the Performance Standard at any time during the
Confirmation Period, the Confirmation Period shall end and sampling and
operation/maintenance of the monitoring wells and extraction/treatment
system shall continue. EPA, in consultation with PADEP, shall again
determine whether the Performance Standard for each contaminant for
which a Performance Standard has been provided in Paragraph 6A, above,
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has been achieved throughout the entire area of groundwater
contamination as described in Paragraph (iv)(a), above.
(c) If EPA, in consultation with PADEP, determines at the close of the
Confirmation Period that no Paragraph 6A contaminant has been detected
in groundwater at a concentration above the Performance Standard at any
time during the Confirmation Period, the extraction/treatment system shall
be shut down. Annual monitoring of the groundwater shall continue for
five years after the groundwater extraction/treatment system is shutdown.
If, subsequent to an extraction/treatment system shutdown, annual
monitoring shows that any Paragraph 6A contaminant is detected in
groundwater at a concentration above the Performance Standard, the
extraction/treatment system shall be restarted and operated/maintained.
EPA, in consultation with PADEP, shall again determine whether the
Performance Standard for each contaminant for which a Performance
Standard has been provided in Paragraph 6A, above, has been achieved
throughout the entire area of groundwater contamination as described in
Paragraph (iv)(a), above.
(d) The extraction/treatment and monitoring system may be modified, as
warranted by performance data during operation, to achieve Performance
Standards. These modifications may include alternate pumping of
extraction well(s) and/or the addition or elimination of certain extraction
wells.
(v) Existing pumping and/or monitoring wells which EPA determines during
long-term monitoring to serve no useful purpose shall be properly plugged and
abandoned consistent with PADEP's Public Water Supply Manual, Part II,
Section 3.3.5.11. Wells which EPA determines are necessary for use during the
long-term monitoring program will not be plugged.
C) Statutory reviews under Section 121(c) of CERCLA shall be conducted as long as
hazardous substances, pollutants, or contaminants remain onsite within the meaning of
that section. Such reviews shall be conducted in accordance with "Structure and
Components of Five-Year Reviews" (OSWER Directive 9355.7-02, May 23, 1991).
9. Institutional Controls - Institutional controls shall be implemented to protect the integrity
of the interceptor trench, groundwater treatment system, soil aeration treatment area, and
phytoremediation area during implementation of the remedial action and operation and
maintenance. At a minimum, these controls shall ensure that no construction, excavation,
or regrading takes place hi these areas except as approved by EPA. Institutional controls
will also be implemented to protect the previously installed soil cover (the area! extent of
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which is between and among the test pits approximated in Figure 4) and will remain in
effect as long as necessary to prevent exposure to contaminated subsoils.
10. Structural stability of open excavations shall be maintained with temporary shoring or
engineering measures as appropriate. Excavation will begin using a backhoe, and the
sides of the excavation area shall be cut back to a minimum 2 to 1 slope to prevent side
wall failure. EPA may approve alternative excavation techniques if such techniques
ensure the same level of Site safety. Air monitoring shall be conducted during
excavations to ensure safety of Site workers and residents living in the vicinity of the
Site.
11. Erosion and sediment (E&S) controls and temporary covers will be installed to protect
exposed soil from the effects of weather consistent with PADEP's Bureau of Soil and
Water Conservation Erosion and Sediment Pollution Control Manual and the Bucks
County Soils Conservation policy. Erosion potential shall be minimized. Further
controls in the form of Site grading to improve land grades, cover soils, vegetation, and
drainage channels to reduce erosion potential from surface runoff may be required to
minimize erosion. Contaminated soils shall be prevented from being washed into onsite
surface water and adjacent uncontaminated and uncontrolled wetland areas during
remedial action implementation. The extent of erosion control necessary will be
determined by EPA, in consultation with the PADEP, during the remedial design phase.
12. Post-excavation sampling will be performed after the excavations are completed. For the
benzene contaminated area, post-excavation samples will be obtained from the base and
the sidewalls of the excavation to ensure that contamination is not present above the soil
cleanup Performance Standards specified in Section X, part A. Excavation hi the TCE
area will extend to the natural boundary of the surrounding wooded wetland so as to not
impact the natural remediation created by this resource. The location of the post-
excavation samples will be selected based on visual observation of lithology and
screening for VOCs using an appropriate organic vapor detector. The samples will be
analyzed for VOCs.
13. For all excavation areas other than the TCE area, the excavation will be backfilled using
clean soil. Clean borrow material will be brought in to restore the excavation to
proximate original grade. Backfilling will be performed, and the material will be
compacted to minimize the potential for subsidence. The excavation area shall be
covered with a layer of cover soil and revegetated with native plant material until a viable
cover is established. The contents of "Office of the Federal Executive; Guidance for
Presidential Memorandum on Environmentally and Economically Beneficial Landscape
Practices on Federal Landscaped Grounds," 60 Fed. Reg. 40837 (August 10,1995) shall
be considered in implementing any landscaping at the Site.
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14. With respect to the benzene-contaminated area, if benzene (or any other VOC) is detected
in the post-excavation samples at levels above any of the soil cleanup Performance
Standards, additional soil will be removed from the excavation area and new samples
obtained and analyzed. Excavation and sampling activities will continue until the results
indicate that the soils do not contain contaminants of concern above any of the
Performance Standards.
15. Excavated soils, drums, and other materials shall be tested to determine the presence of
RCRA characteristic wastes. All RCRA characteristic wastes shall be handled in
accordance with Pa. Code §§ 262.11 - 262.13 (relating to hazardous waste determination
and identification numbers), 25 Pa. Code § 262.34 (relating to pretransport requirements);
25 Pa. Code Chapter 263 (relating to transporters of hazardous wastes); and with respect
to the operations at the Site generally, with the substantive requirements of 25 Pa. Code
Chapter 264, Subchapters B-D, I (in the event that hazardous waste is generated as part of
the remedy).
XL STATUTORY DETERMINATIONS
The following sections discuss how the selected remedy for the Boarhead Farms Site meets the
statutory requirements contained in CERCLA.
A. Overall Protection pf Human. .Health and the Environment
The Baseline Risk Assessment (BLRA) conducted* at the Boarhead Farms Site describes the risks
to human health resulting from contamination at the Site. Onsite residents consuming
groundwater from the onsite residential wells are at the highest risk. In addition, risks above the
Hazard Index of 1 are present for offsite residents downgradient from the Site consuming
groundwater from residential wells, onsite workers consuming contaminated groundwater,
recreational Site users in the wetlands areas, and recreational offsite users consuming fish from
the culverts and creeks running from the Site. Implementation of Uternative 6 at the Boarhead
Farms Site will eliminate all unacceptable human health and ecological risks identified in the
BLRA.
Soil aeration and treatment of TCE and benzene soil hot spots called for in the selected remedy
will reduce the risk of exposure to high levels of contamination in the hot spot areas. In addition,
soil aeration will eliminate the possibility of TCE and benzene leaching into the groundwater
from the hot spot soils.
Excavation and offsite disposal of the remaining buried drums and associated soils will reduce
to acceptable levels the risk of the contaminants associated with the drums leaching into the
groundwater or further contaminating the surrounding soils. Filling in these excavated areas will
reduce the potential of future exposure to contaminated soils through ingestion and direct
contact.
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Groundwater extraction, metals precipitation, and air stripping through upgrading the existing
groundwater treatment facility will reduce the potential of contaminated groundwater moving
offsite. The upgraded system will remove VOC and metals contamination from all groundwater
flowing into the interceptor trench and extraction wells, and treated groundwater will be
discharged to the adjacent wetland areas. This will reduce the risks of exposure through
inhalation, ingestion and dermal contact to ofFsite residents.
Implementation of the selected remedy will not pose any unacceptable short term risks or cross
media impacts to the Site or the community.
B- Compliance with Applicable or Relevant and Appropriate Requirements f ARARst
The selected remedy will comply with all applicable or relevant and appropriate chemical-
specific, location-specific and action-specific ARARs as discussed above in Section X of this
ROD.
C. Cost-Effectivenesg
The selected remedy is cost-effective in providing overall protection in proportion to cost, and
meets all other requirements of CERCLA. Section 300.430(f)(l)(ii)(D) of the NCP requires EPA
to evaluate cost-effectiveness by comparing all the alternatives which meet the threshold criteria
- protection of human health and the environment and compliance with ARARs - against three
additional balancing criteria: long-term effectiveness and permanence; reduction of toxicity,
mobility or volume through treatment; and short-term effectiveness. The selected remedy meets
these criteria and provides for overall effectiveness in proportion to its cost.
The combined estimated present worth cost for the selected remedy presented in this Record of
decision is $13,157,000.
D- Utilization of Permanent Solutions and Alternative Treatment Technologies tp th^
Maximum Extent Practicable
EPA has determined that the selected remedy represents the maximum extent to which
permanent solutions and treatment technologies can be utilized while providing the best balance
among the other evaluation criteria. Of those alternatives evaluated that are protective of human
health and the environment and meet ARARs, the selected remedy provides the best balance of
tradeoffs in terms of long-term and short-term effectiveness and permanence, cost effectiveness,
implementability, reduction in toxicity, mobility, or volume through treatment, State and
community acceptance, and preference for treatment as a principal element.
Under the selected remedy, groundwater treatment using air stripping and metals precipitation is
more cost effective than UV oxidation. The air stripper unit will achieve the same purpose as
UV oxidation, but at a lower cost.
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Soil aeration at the TCE and benzene hot spot areas reduces volume, toxicity, and mobility of
soil contaminants and reduces both short-term and long-term risks of exposure. Additionally,
soil aeration provides long-term effectiveness and permanence. Soil aeration was chosen over
other soil remediation techniques since it is more cost effective and removes the source of VOC
contamination in the soil hot spot areas. In addition, it eliminates the possibility of further
leaching of the TCE and benzene into groundwater hi the selected hot spots.
E- Preference for Treatment as a Principal Element
The selected remedy satisfies the preference for treatment in that it employs treatment to address
the principal threat posed by conditions at the Site. The interceptor trench and treatment system
provide active treatment to hazardous substances entrained in the surfical aquifer and the
mechanical aeration and air filtration will further reduce the amount of VOCs being released into
the environment. The principal threats of ingestion and inhalation of, and dermal contact with,
contaminated groundwater to offsite residents will be eliminated. In addition, the toxic burden to
the groundwater will be significantly reduced.
XII. DOCUMENTATION OF CHANGES FROM PROPOSED PLAN
The Proposed Plan identifying EPA's preferred alternative for the Site was released for comment
on January 5,1998. During the public comment period, EPA received numerous comments from
the public regarding EPA's Proposed Remedy. These comments are presented in detail in Part
III of this ROD, the Responsiveness Summary. Although EPA has not made any significant
changes with regards to the Proposed Plan, a few actions have been added.
The description of Alternative 1, No Action, as written in the Proposed Plan, has been changed to
explain shut down of the groundwater remediation system with no further remediation taking
place on the Site. In addition, EPA determined that Alternative 2 is more accurately
characterized as "Continued Maintenance and Monitoring of the Existing Groundwater
Interceptor Trench, Treatment Facility, and Residential Well GAC Filters; Institutional
Controls."
Institutional controls were added to protect the previously installed soil cover (the aeral extent of
which is between and among the test pits approximated in Figure 4).
As a result of public comment and further research, EPA added to the selected alternative the
performance of a treatability study during Remedial Design to determine if phytoremediation
will aid in cleanup in the main areas of the Site. If, based on the results of such treatability
studies, EPA determines that phytoremediation will aid in the cleanup of the Site, vegetation that
aides in the uptake of metals and VOCs from the groundwater and soil will be planted in a layer
of clean soil overlaying the excavation areas. The goal of phytoremediation is for the plant life
to reduce the level of contaminants in the groundwater in the shallow system toward the
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interceptor trench, and treat the water through biological processes. EPA does not anticipate a
large rise in cost from the additional plant and soil cover.
At the request of several community members, the remedy will include a minimum of two new
monitoring wells located in the area between the areas of contamination and the downgradient
residents. The purpose of these wells will be to provide additional information to both the
community and EPA regarding the effectiveness of the selected remedial action. In addition,
EPA will continue to sample the residential and monitoring wells both onsite and in the
surrounding areas. If the levels of contaminants rise in the perimeter monitoring wells or
residential wells, EPA will consider modifications to the remedy.
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APPENDIX A - TOXICOLOGICAL PROFILES OF SELECTED SITE CONTAMINANTS
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1,1-Dichloroethene (1,1-DCE)
1,1 -DCE is used to make certain plastics, such as packaging materials and flexible films like
SARAN wrap, and flame -retardant coatings for fiber and carpet backing. It is a clear, colorless
liquid and has a mild, sweet smell like chloroform. 1,1-DCE is considered highly volatile and
readily migrates to the atmosphere, where it is photo-oxidized by reaction with hydroxyl radicals.
It readily volatilizes through the air-filled pores in near-surface soils. Based on a soil sorption
coefficient (K^.) value of 65, this compound is expected to be only weakly sorbed to soils. This
compound is not expected to undergo hydrolysis or microbial degradation in natural systems. In
unsaturated near-surface soils, depending on several factors, including percent organic material,
about 60 percent of the compound is expected in the gaseous phase, with only 3 percent in the
aqueous phase and the remainder absorbed to soil. In deeper soils, 78 percent of the compound
is expected to be in the aqueous phase. That portion of the compound that does not volatilize
from soil may be expected to be mobile in groundwater.
EPA reports a chronic oral RfD of 9.0 x 10'3 mg/kg-day with the stipulation that the RfD is
currently under review (IRIS, 1995). This RfD has an uncertainty factor (UF) of 1000. The
confidence in the study, the database, and the RfD is medium. EPA lists the same value for the
interim subchronic RfD (HEAST, 1992). No inhalation RfCs are available, however a risk
assessment for this compound is under review by an EPA work group (IRIS, 1995).
The oral RfDs were derived from a chronic oral bioassay in which rats were provided drinking
water containing either 50, 100, or 200 mg/L 1,1-dichloroethene. The authors calculated intakes
to be 7, 10, and 20 mg/kg/day for male rats and 9, 14, and 30 mg/kg/day for female rats (IRIS,
1995). The female rats evidenced hepatic lesions at all exposure levels, while the males only
showed a significant effect at 200 mg/L. Therefore, the LOAEL was set at 9 mg/kg- day; a
NOAEL could not be determined.
1,1-DCE has been classified by EPA (IRIS, 1995) as a group C (possible human) carcinogen.
This classification indicates limited evidence of carcinogenicity in animals with inadequate
evidence of human carcinogenicity and is based on the results of tumors observed in one mouse
strain following an inhalation exposure to 25 ppm of 1,1-DCE for 5 days/week for 52 weeks
(IRIS, 1995). EPA has established an oral CSF of 0.6 (mg/kg/day)-1 (IRIS, 1995) and an
inhalation Carcinogenic Slope Factor (CSF) of 0.18 (mg/kg/day)-' (IRIS, 1995). The oral CSF is
only valid if the water concentration is below 600 mg/L, and the inhalation CSF is only valid if
the air concentration is less than 200 mg/m3.
EPA lists a one-day health advisory of 2 mg/L and a ten-day health advisory of 1 mg/L (Drinking
Water Standards and Health Advisories). The ambient water quality criteria for water and fish
consumption is 3.3 x 10-2 mg/L and for fish ingestion only is 1.85 mg/L.
EPA (1986) reports an acute concentration of 11,600 mg/L for the dichloroethenes as the LOEC
in aquatic systems. 1,1-DCE has a relatively low octanol/water partition coefficient (5.37) and a
BCF range from 20 to 30, which indicates that 1,1-DCE may not accumulate significantly in
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animals (Lyman et al., 1982). 1,1-DCE is not very toxic to freshwater or saltwater fish species,
with acute LC50 values ranging from 80 to 200 mg/L (EPA, 1980).
cis-1,2-DCE and trans-l,2-DCE
1,2-DCE exists in two isomeric forms, cis-1,2-DCE and trans-1,2-DCE, that are colorless,
volatile liquids with a slightly acrid odor. 1,2-DCE is prepared commercially by either the direct
chlorination of acetylene or by the reduction of 1,1,2,2-TCA with fractional distillation used to
separate the two isomers. 1,2-DCE can also be formed as a by-product during the manufacture
of other chlorinated compounds. Commercial use is not extensive, but trans-1,2-DCE and
mixtures of cis- and trans-1,2-DCE have been used as intermediates in the production of other
chlorinated solvents and compounds, as well as low temperature extraction solvents for dyes,
perfumes, and lacquers. Both cis- and trans-1,2-DCE are moderately flammable and react with
alkalis to form chloracetylene gas, which spontaneously ignites in air.
Information on the toxicity of 1,2-DCE in humans and animals is limited. Workers acutely
exposed to 1,2-DCE have been reported to suffer from drowsiness, dizziness, nausea, fatigue and
eye irritation. Acute and subchronic oral and inhalation studies of trans-1,2-DCE and acute
inhalation studies of cis-1,2-DCE indicate that the liver is the primary target organ in animals;
toxicity being expressed by increased activities of liver associated enzymes, fatty degeneration
and necrosis. Secondary target organs include the central nervous system and lung.
Limited information exists on the absorption, distribution, and excretion of 1,2-DCE in either
humans or animals. In vitro studies have shown that the mixed function oxidizes will metabolize
1,2-DCE; the final metabolic products are dependent on the initial isomer of 1,2-DCE.
On the basis of an unpublished study describing decreased hemoglobin and hematocrits in rats
treated by gavage for 90 days, EPA (1990 a, b) assigned a subchronic and chronic oral RfD for
cis-l,2-DCE of 1E-1 mg/kg/day and 1E-2 mg/kg/day, respectively. The RfDs were derived from
a NOAEL Lowest Observed Adverse Affect Level (LOAEL) of 32 mg/kg/day. An inhalation
RfC for cis-1,2-DCE has not been derived.
Subchronic and chronic RfDs of 2E-1 mg/kg/day and 2E-2 mg/kg/day, respectively, for
trans-1,2,-DCE have been calculated. The RfDs were derived from a LOAEL of 175 mg/kg/day
based on the increase of serum alkaline phosphatase activity in mice that received trans-1,2-DCE
in their drinking water. An RfC for trans-1,2-DCE has not been derived.
No information was available concerning the chronic, developmental or reproductive toxicity of
cis-1,2-DCE or trans-1,2-DCE. No cancer bioassays or epidemiological studies were available to
assess the carcinogenicity of 1,2-DCE. EPA has placed cis-1,2-DCE in weight-of-evidence
Group D (not classifiable as to human carcinogenicity) based on the lack of human or animal
carcinogenicity data and on essentially negative mutagenicity data. Trans-1,2-DCE has not been
classified.
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Because of its volatility, the primary route of 1,2-DCE exposure to humans is by inhalation,
although dermal and oral exposure can occur. Exposure to 1,2-DCE may occur as a result of
releases from production and use facilities, from contaminated waste disposal sites and
wastewater, and from the burning of poly vinyl and vinyl copolymers. 1,2-DCE contaminates
groundwater supplies by leaching from waste disposal sites. Therefore, human oral, dermal, and
inhalation exposure can occur from drinking and using water, and by breathing vapors from 1,2-
DCE-contaminated supplies and delivery systems.
Tetrachloroethene (PCE)
PCE is a halogenated aliphatic hydrocarbon. It is a colorless liquid with a molecular weight of
165.85 and a vapor pressure of 17.8 mm Hg at 25 °C. PCE has a half-life of 47 days in the
atmosphere and 30 to 300 days in surface water and groundwater. PCE is used primarily as an
industrial solvent for a number of applications, and is routinely used in laundry and dry cleaning
operations. Inhalation exposure is the primary concern for workers. The general public can also
be exposed to PCE by inhalation, mainly in areas of concentrated industry and population. Some
of the highest outdoor air levels (up to 58,000 ppt) have been associated with waste disposal
sites. Exposure can also occur through contact with contaminated food and water supplies. An
estimated 7 to 25 percent of the water supply sources in the United States may be contaminated
with PCE.
The main targets of PCE toxicity are the liver and kidneys by both oral and inhalation exposure,
and the central nervous system (CNS) by inhalation exposure. Acute exposure to high
concentrations of the chemical (estimated to be greater than 1500 ppm for a 30-minute exposure)
may be fatal. Chronic exposure causes respiratory tract irritation, headache, nausea,
sleeplessness, abdominal pains, constipation, cirrhosis of the liver, hepatitis, and nephritis in
humans; and microscopic changes in renal tubular cells, squamous metaplasia of the nasal
epithelium, necrosis of the liver, and congestion of the lungs in animals.
RfDs for chronic and subchronic oral exposure to PCE are 0.1 mg/kg/day and 0.01 mg/kg/day,
respectively (Buben and Flaherty, 1985; USEPA, 1990; 1991). These values are based on
hepatotoxicity observed in mice given 100 mg PCE/kg body weight for six weeks and a NOAEL
of20mg/kg.
Epidemiological studies of dry cleaning and laundry workers have demonstrated excesses in
mortality due to various types of cancer, including liver cancer, but the data are regarded as
inconclusive because of various confounding factors. The tenuous finding of an excess of liver
tumors in humans is strengthened by the results of carcinogenicity bioassays in which PCE,
administered either orally or by inhalation, induced hepatocellular tumors in mice. PCE was
negative for tumor initiation in a dermal study and for tumor induction in a pulmonary tumor
assay.
Based on the sufficient evidence from oral and inhalation studies for carcinogenicity in animals
and no or inadequate evidence for carcinogenicity to humans, PCE is placed in EPA's weight-of-
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evidence Group B2 (probable human carcinogen). For oral exposure, the slope factor is 5.1x10'2
(mg/kg/day)'1; the unit risk is 1.5 x 10'6 (mg/L)'1. For inhalation exposure, the slope factor was
calculated as 2.03 x 10'3 from the unit risk of 5.2 x 10'7 (mg/m3/7.
Trichloroethene (TCE)
TCE is a colorless, stable liquid with a chloroform like odor. It has a molecular weight of 131.5,
a vapor pressure of 60mm Hg at 20°C, and a solubility of 1,100 mg/1 at 25°C. TCE is considered
slightly soluble in water and is miscible with common organic solvents. TCE is used as a metal
degreaser, as an extraction solvent for oils, fats, and waxes, for solvent dyeing, in dry cleaning,
and for cleaning and drying electronic parts.
Inhalation exposure is the most likely route for human contact with TCE. Systemic health
effects have generally been reported only when people are exposed to TCE levels above the odor
threshold. There are a few case reports of humans exhibiting kidney and liver damage following
exposure to very large amounts of TCE.
There is no reliable information concerning the adverse systemic effects of chronic exposure to
levels of TCE below the threshold limit value of 50 ppm. Neurological effects reported in
workers exposed for less than 15 years to relatively high mean TCE levels (167 ppm) include
vertigo, fatigue, headache, and short-term memory loss. The number of symptoms increased
with cumulative exposure time.
EPA's IRIS database currently does not list a chronic oral or inhalation RfD for TCE. The
chronic systemic toxicity of TCE is currently under review by the RfD workgroup. Pending this
review, a provisional chronic oral RfD of 6E-3 mg/kg-day was issued by ECAO (now NCEA) in
1992, based on the subchronic mouse study by Tucker, et al (1982). The critical effect seen in
this study was liver toxicity following oral administration.
Animal studies have shown increases in cancers of various types following inhalation or oral
exposure to TCE. These cancer types include cancer of the liver and forestomach in mice, and
cancer of the kidney and testes hi rats. It is believed that tumor production by TCE is the result
of metabolites of TCE. There are differences between high- and low-dose metabolism of TCE,
as well as differences between species' susceptibility to cancer. Given that enormous worker
populations have been exposed to TCE, and that only a small number of persons have
experienced chronic effects, it is possible that TCE is not metabolized to the active carcinogen
level in humans at low environmental doses. The mechanisms of carcinogenicity are not known.
EPA has classified TCE as a Class B2 (adequate evidence in animals but insufficient evidence in
humans) carcinogen.
Mutagenesis studies have suggested that TCE is only very weakly genotoxic following metabolic
activation. The Health Assessment Document concludes that there is insufficient evidence to
prove that TCE is mutagenic.
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1,1,1-Tricholoroethane (1,1,1-TCA)
1,1,1-TCA (1,1,1,-TCA-memylchloroform) has a sweet odor that may be noticeable at
concentrations near 100 ppm, significantly lower than those that cause physiologic response. At
1000 ppm the odor is not unpleasant enough to discourage exposure; at 1500 and 2000 ppm, the
odor is strong and unpleasant. 1,1,1-TCA has a molecular weight of 133.42, a specific gravity of
1.3249 (26/4°C), and a vapor pressure of 127 torr at 25 °C. It is soluble in acetone, benzene,
carbon tetrachloride, methanol, and ether, but insoluble in water.
1,1,1-TCA is absorbed through inhalation, oral, and dermal exposure routes. Clearing of the
chemical from the blood is rapid following exposure; 60 to 80 percent is eliminated within 2
hours, and more than 95 percent is eliminated within 50 hours. A large fraction of the absorbed
dose is excreted unchanged in exhaled air regardless of the route of exposure. The chemical has
been detected in the fat, liver, kidney, brain, muscle tissue, and skin of animals. Humans
metabolize less than 10 percent of the inhaled dose of 1,1,1-TCA.
Little is known about the oral toxicity of 1,1,1-TCA. One case study reported gastrointestinal
and hepatic effects in an individual who accidentally ingested approximately 600 mg/kg of the
chemical. Death in most cases has been attributed to depression of the central nervous system
resulting from anesthesia.
1,2-Dichloropropane
1,2-Dichloropropane is a colorless liquid with the odor of chlorinated solvent. The chemical is
volatile and evaporates quickly at room temperature. It is used as an industrial solvent for fats,
oils, resins, waxes, and rubber; in manufacturing photographic film; and for coating paper.
Experiments in animals have shown that when 1,2-dichloropropane enters the body through
ingestion, is removed quickly in urine and feces and by the lungs during exhalation.
Human ingestion through drinking (e.g., drinking cleaning solutions) has resulted in poisoning.
At high levels of exposure, effects include dizziness, headache, nausea, injury to the liver and
kidneys, anemia, coma, and ultimately death. There have been reports of health effects hi
humans following low level exposure for either short or long periods. Exposure has not been
shown to cause cancer in humans, but long-term exposure in animals has produced evidence of
liver cancer in mice and breast cancer in female rats.
The major releases of 1,2-dichloropropane are to the atmosphere and to soil. When applied to
soil or landfilled, it partially volatizes and the remainder leaches into subsurface soil and
groundwater. Volatilization is unlikely in groundwater, where the principal reaction are
hydrolysis and anaerobic biotransformation. Therefore, groundwater supplies contaminated with
1,2-dichloropropane may remain so for a long time.
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Vinyl Chloride (VC)
In humans, exposure to VC can result in irritation of the respiratory tract, bronchitis, headache,
irritability, memory disturbances, and tingling sensations. Acute occupational exposure to high
concentrations of VC can produce symptoms of narcosis, and may even lead to death. In animals
ataxia, narcosis, blood-clotting difficulties, congestion and edema in lungs, and kidney and liver
effects have been observed. At high doses, excitement, convulsions and an increase in
respiration followed by respiratory failure precede death. Human health effects associated with
chronic occupational exposure to VC include hepatitis-like liver changes, decreases in blood
platelets, enlarged spleens, decreased pulmonary function, cardiovascular and gastrointestinal
toxicity, and disturbances in vision and the central nervous system.
VC is a known human carcinogen that causes liver angiosarcomas ( a rare tumor in humans) and
possibly increases the incidence of tumors of the brain, the lung, and the hemolymphopoitic
system in humans. VC is carcinogenic in mice, rats, and hamsters.
VC is mutagenic in several test systems. Chromosome aberrations have been reported in
exposed workers. In humans, possible relationships between exposure and birth defects and fetal
death have been reported. Increased skeletal variants were found in offspring of mice exposed
during gestation.
Benzene
Benzene is a clear, volatile, colorless, highly flammable liquid having a characteristic odor.
Benzene occurs naturally hi many plants and animals and also serves as a major industrial
chemical produced from coal and oil. In industry, benzene is used as a solvent and as a
component of motor fuels, such as gasoline. Due to the quick evaporation rate of benzene, the
most common route of exposure to humans is through inhalation of contaminated air. Small
amounts of benzene are found hi some foods, in contaminated drinking water, and in cigarette
smoke. Benzene is absorbed into the blood stream from either the gastrointestinal tract after
ingestion or into the lungs after inhalation. It may also be absorbed through the skin at a very
slow rate. After ingestion or inhalation, humans and animals tend to eliminate benzene
unchanged in the exhaled air or in a metabolized form in urine and feces.
The principal acute toxic effect of benzene in humans and other animals is on the central nervous
system, the blood-making system, and the immune system. Inhalation of high concentrations of
benzene (10,000 to 20,000 ppm for 5 to 10 minutes) may be fatal. Lower-level exposures (700 to
3000 ppm) can cause dizziness, drowsiness, headaches, and unconsciousness. Dermal contact
with benzene may cause redness and blisters. Autopsies of persons who have died following
inhalation of high concentrations of benzene have shown inflammation of the respiratory tract
and damage to the lungs, the kidneys, and the brain. Ingestion of high doses of benzene (10 ml,
the reported lethal oral dose for humans) has produced staggering gait, vomiting, shallow and
rapid pulse, and loss of consciousness, followed by delirium, pneumonitis, collapse, and sudden
depression of the central nervous system, leading to coma and death.
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Studies of chronic exposure to benzene by humans and animals have shown that benzene inhibits
blood-cell formation and can cause leukemia. Evidence of carcinogenicity also exists. Benzene
has been reported as being genotoxic, causing chromosome aberrations in the bone marrow of
persons occupationally exposed. A relationship between benzene exposure and development of
leukemia has been reported in epidemiological studies. It has been classified as a Group A
carcinogen (known human carcinogen) by EPA.
The most significant source of benzene released to the environment is through the combustion of
gasoline. It is noted to evaporate easily from surface water and soil, and if released to soil or
water may volatize, photoxidize, and biodegrade. Bioconcentration of benzene in aquatic
organisms is not considered likely. Benzene is fairly soluble in water and can leach from soil
into groundwater.
Ethyl Benzene
Ethyl benzene is used as an intermediate in producing styrene, in the manufacture of cellulose
acetate and synthetic rubber, as a diluent in the paint industry, in agricultural sprays for
insecticides, and in gasoline blends. Primary routes of exposure include drinking water,
breathing air, and touching soil contaminated with ethyl benzene.
Symptoms of short term human exposure to ethyl benzene include eye, nose, throat, and skin
irritation, narcosis (at very high concentrations), dizziness, drowsiness, weakness, and dermatitis.
Long-term data are limited, but evidence exists that ethyl benzene may cause liver and kidney
injury and that it may be a teratogen at high doses. EPA has classified ethyl benzene as a Group
D carcinogen (not classifiable as to human carcinogenity).
When released to the atmosphere, it exists predominantly in the vapor phase, where it
photochemically degrades by reacting with hydroxyl radicals and partially returns to earth in
rain. However, it is not subject to direct photolysis. Ethyl benzene in water evaporates and
degrades, the primary removal process depends on season, turbule ice, and microbial
populations. Some of the chemical may be absorbed by sediment, but insignificant
bioconcentration in fish is not expected. When released to soil it is moderately absorbed and
may leach to groundwater, where biodegradation is possible. Ethyl benzene will not hydrolyze
significantly in water or soil.
Toluene
Toluene is a clear, colorless liquid having a sweet odor. It is produced from petroleum refining,
as a by-product of styrene production, and as a by-product of coke oven operations. Toluene is
used in making paints, lacquers, adhesives, rubber, and in some leather-tanning and printing
operations. It enters the body through inhalation, ingestion, or dermal contact. The chemical is
absorbed rapidly through the lungs, in the gastrointestinal track, and through the skin. Most of
the toluene is removed from the body within 12 hours, either unchanged through expired air or
chemically changed through urine.
-------
Acute and subacute inhalation exposure to toluene vapor result in symptoms indicating toxicity
to the central nervous system. Animal studies indicate that acute oral toxicity is relatively low
Chronic exposure to toluene vapors has been associated primarily with effects on the central
nervous system and, possibly, effects on peripheral systems. Liver and kidney functions may
also be effected by chronic exposure. Reproductive effects and birth defects, including cleft
palate, delayed skeletal development, and fetotoxicity, have been reported. However, studies of
workers and animals exposed to toluene indicate that toluene is not a carcinogen. EPA has
classified toluene as a Group D carcinogen.
Toluene is relatively mobile in soil-water systems, including transport of vapor through air-filled
pores and transport in solution. It is resistant to hydrolysis but biodegrades readily in the
presence of micrbbial populations. Toluene has a moderate tendency to bioaccumulate in the
fatty tissues of aquatic species.
Nitrobenzene
Nitrobenzene is an oily yellow liquid having an almond-like odor. It is manufactured by industry
mainly for producing the chemical, aniline. It may also be found in lubricating oils for
machinery, dyes, drugs, pesticides, and synthetic rubber. Nitrobenzene may enter the human
body through ingestion, inhalation, and dermal exposure. It is eliminated from the body within a
few days through the urinary tract.
Medical reports show that acute exposure causes mild irritation of the skin and eyes. Chronic
exposure decreases the blood's ability to carry oxygen, and may cause vomiting, shortness of
breath, and nausea. Other possible symptoms of exposure include irritability, weakness,
headache, dizziness, and drowsiness. Extremely high exposure may induce a coma and even
death if medical attention is not received promptly.
Nitrobenzene enters the environment through releases to water and air in liquid form The
chemical will biodegrade in a matter of days and is only slightly mobile in water.
Arsenic
The toxicity of inorganic arsenic (As) depends on its valence state and on the physical and
chemical properties of the compound in which it occurs. Trivalent (As+3) compounds are
generally more toxic than pentavalent (As+5) compounds, and the more water-soluble
compounds usually are more toxic and more likely to cause systemic effects than the less soluble
compounds. The less soluble compounds are more likely to cause chronic pulmonary effects if
inhaled.
Water soluble inorganic As compounds are absorbed through the gastrointestinal tract and the
lungs; distributed primarily to the liver, kidney, lung, spleen, aorta, and skin; and excreted
mainly in urine at rates as high as 80 percent in 61 hours after oral dosing. Symptoms of acute
inorganic arsenic poisoning in humans are nausea, anorexia, vomiting, epigastric and abdominal
-------
pain, and diarrhea. Oral doses as low as 20 to 60 mg/kg/day have reportedly caused toxic effects
in some individuals. General symptoms of chronic As poisoning in humans are weakness,
general debility and lassitude, loss of appetite and energy, loss of hair, hoarseness of voice,
weight loss, and mental disorders. Primary target organs are the skin and the vascular system.
Epidemiological studies have revealed an association between As concentrations in drinking
water and increased incidence of skin cancers and cancers of the liver, bladder, and respiratory
and gastrointestinal tracts. Occupational-exposure studies have shown a clear correlation
between exposure to As and mortality from lung cancer. EPA has places inorganic arsenic in
Group A, human carcinogen. Arsenic is cleared from the body relatively rapidly, primarily in
urine, but also in hair and nails.
Aluminum
Aluminum is a silver-white flexible metal that occurs naturally combined with other elements as
ore in the earth's crust. Aluminum is used in antacids and deodorants, and as a metal hi cooking
utensils, appliances, and building materials. The main route of absorption is through ingestion.
The extent of absorption depends somewhat on the chemical form. Trivalent aluminum is
absorbed into the intestinal mucosa to a minor extent and then is transferred into the lungs,
plasma, bone, and cells of various organs. Aluminum is excreted hi feces and to a limited extent
in urine.
The acute toxicity of aluminum is not well defined. Possible target organs include the brain and
bone. Inhalation of aluminum dust has resulted in irritation of airways and possible fibrosis of
the lungs in aluminum-industry workers. Acute dermal exposure hi humans has resulted in skin
rashes. Chronic exposure has been associated with Alzheimer's disease in humans. At autopsy,
neurofibrillary tangles containing aluminum have been found hi the cerebral cortex and
hippocampus of Alzheimer patients.
Aluminum partitions into air, water, soil, and plant material. It is transported in the atmosphere
as a constituent of soil and other particulate matter. Transformation is not expected in the
atmosphere. Aluminum partitions between the soil-sediment and aqueous phases by reacting and
complexing with water molecules, anionic compounds, and negatively charged functional groups
on humic materials and clay. Bioaccumulation does not appear significant.
Antimony
Antimony is a silvery-white metal of medium hardness that breaks easily. It is used as a
component of lead and zinc alloys that are used in lead storage batteries, solder, sheet and pipe
metal, bearings, castings, type metal, ammunition, and pewter. Exposure may occur through
ingestion of food or water, through breathing air, or through contact with soil, water, or other
substances that contain antimony. Skin contact and inhalation are common occupational
exposures. Most absorbed antimony is transported to the liver, the lungs, the intestines, and the
spleen. Within several weeks antimony is excreted in feces and urine.
-------
Acute symptoms of antimony exposure are diarrhea, vomiting, gastric discomfort, and ulcers
following oral ingestion of large quantities. Animal studies indicate that acute exposure may
result in lung, heart, liver, and kidney damage, eye irritation, and skin irritation. Subchronic
exposure through inhalation leads to heart problems, stomach ulcers, pneumoconiosis, and eye
and skin irritation. Animal studies indicate that subchronic ingestion may cause diarrhea, weight
loss, liver damage, and decreased red blood cell count.
Antimony in the atmosphere is hi the form of paniculate matter or is absorbed to particulate
matter. It is transported to land and surface water through gravitational settling and other forms
of dry and wet deposition. In the aquatic environment, antimony tends to settle out in areas of
active sedimentation. Some forms of antimony are strongly sorbed to soil, making it relatively
immobile. It may also absorb strongly to colloidal materials in soil and may be transported to
groundwater. Antimony does not appear to bioconcentrate in fish and aquatic organisms.
Beryllium
Beryllium is a naturally occurring dark-gray metal of the alkaline earth family. Natural
atmospheric emissions of beryllium originate from volcanic particles and windblown dust. The
source is small in comparison to the anthropogenic sources such as ore processing and coal and
fuel combustion. Bertrandite ore deposits are mined and processed to produce beryllium metal,
alloys, and oxide. These forms of beryllium have commercial uses in certain items, such as
electrical components, tools, and structural components for aircraft, missiles, and satellites.
Inhalation of beryllium is the major route of environmental exposure. Both oral and dermal
exposure are secondary routes since absorption by the gastrointestinal tract and the skin is poor.
When absorbed, beryllium circulates hi the bloodstream as an orthophosphate colloid.
Distribution favors the skeleton, liver, and kidneys. After inhalation exposure, most of the
absorbed beryllium is excreted in urine.
The lungs are the primary organ affected by beryllium exposure. Studies show that acute
exposure to an aerosol of soluble beryllium results in chronic pneumonitis in laboratory animals
and in humans exposed in the workplace. Acute dermal exposure to soluble beryllium
compounds causes contact dermatitis.
There is no evidence indicating that beryllium produces a carcinogenic response following oral
or dermal exposure in animals or humans. Evidence exists that various inhaled beryllium
compounds can induce lung tumors in monkeys and several strains of rats. EPA classifies
beryllium as a B2 carcinogen (probable human carcinogen), although human epidemiology
studies of workplace exposure are inadequate to clearly establish human carcinogenicity.
Due to low solubility, beryllium oxide is not expected to be mobilized in soil or surface water of
normal pH (5 to 8). Beryllium is expected to be absorbed tightly in most soil types since it
displaces divalent cations. Therefore, environmental movement through leaching from soil or
solubilizing in the water column appears minimal.
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Cadmium
Cadmium is naturally occurring bluish-white metal usually found in combination with other
elements (cadmium oxide, cadmium chloride, and cadmium sulfide). These compounds are
stable solids. Since many edible plants and fish take up cadmium from soil or water sources,
food is the primary exposure route for humans. Airborne exposures also can occur. Cadmium is
poorly absorbed from the gastrointestinal tract after ingestion but relatively well absorbed from
the lungs after inhalation.
Acute oral and inhalation exposure results in severe irritation to the stomach and lungs. At high
doses, injury to the testes and liver may occur. The kidney is the major target organ.
Reproductive and developmental effects also have been observed in animals. In addition,
evidence of lung fibrosis emphysema and lung cancer in humans are associated with chronic
exposure to inhaled cadmium. EPA classifies cadmium as a Group Bl (probable human
carcinogen with limited human data available).
In surface water or groundwater, cadmium can exist as a hydratedion or as ionic complexes with
organic or inorganic ligands. It may also exist hi insoluble forms and be absorbed to particulate
matter, soil and sediment. Cadmium is bioaccumulated in microorganisms through exposure to
food and water.
Chromium
Chromium is a naturally occurring steel-gray lustrous metal used in metal alloys, chrome plating,
and various other industrial processes. It occurs naturally in foods and is considered vital to the
metabolism of fats and sugars. Chromium appears in several chemical states, with hexavalent
chromium being the most toxic and most often seen in waste streams. Absorption occurs
through inhalation, ingestion, and skin contact. Although it can accumulate in various organs,
particularly the lungs, the majority of absorbed chromium is excreted quickly through the urinary
tract.
Inhalation of chromium by workers for less than one year has resulted in irritation of the mouth
and throat, sneezing, redness of the throat and generalized bronchial spasms. Dermal exposure
results in skin ulcers that may penetrate deeply into soft tissue. Accidental ingestion by humans
has resulted in intense gastrointestinal effects, bleeding, circulatory collapse, unconsciousness,
and death. Epidemiological evidence indicates a strong relationship between occupational
chromium exposure and respiratory-system cancers, particularly lung, bronchogenic, and nasal
cancer. EPA classifies chromium as a Group A carcinogen (human carcinogen).
Airborne chromium is removed from the atmosphere primarily by fallout and precipitation and
enters surface water and soil. It does not absorb to clay or other inorganic surfaces. Chromium
is mobile in groundwater and in aquatic media, will filtrate into the sediment. The chemical does
not bioconcentrate in fish and there is no evidence of biomagnification of chromium along the
-------
aquatic food chain. Some data indicate that chromium has a low mobility for translation from
roots to aboveground plants.
Manganese
Manganese is a naturally occurring metal that is mixed with iron to make steel, used in producing
batteries, and used as a component of some ceramics, plastics, and fertilizers. It is an essential
nutrient for humans. Following oral exposure, most manganese is excreted in feces, and about
three to five percent is taken up and stored in the body. Manganese-contaminated dust may
become trapped in the lungs following inhalation, and some of the particles may then dissolve in
the lungs and enter the bloodstream. Manganese is not readily absorbed through the skin.
Chronic inhalation exposure to manganese dust in occupational settings has shown strong
evidence of severe neurological damage in humans. A disease, known as "manganism",
typically begins with feelings of weakness and lethargy. As the disease progresses, the central
nervous system can be affected and psychological disturbances can occur. In advanced cases,
permanent muscle rigidity may develop. EPA has assigned a weight-of-evidence classification
of Group D (no conclusive evidence as to human carcinogenicity) for manganese.
Manganese may occur in the air as suspended particles and will settle out according to particle
size. Depending on its chemical form, manganese may be soluble in water, and is often
transported in rivers as suspended sediment The absorption of manganese to soil is highly
variable and depends on soil composition. Lower organisms, such as algae, appear to
bioconcentrate manganese, but higher organisms do not. This suggests that biomagnification in
the food chain is not significant.
Nickel
Nickel is a silvery metal occurring naturally in Earth's crust in various minerals. Nickel and its
compounds are found in the air, groundwater, surface water, and. oil. Industrial nickel is
obtained from mined ore and recycled scrap metal. Industrial mexal is used predominantly in
making various steels and alloys and in electroplating. Other uses include electrical contacts and
electrodes, spark plugs, machinery parts, nickel-chrome resistance wire, stainless steel, and
electronic and space applications.
Studies indicate that humans absorb little nickel following inhalation or oral exposure. Limited
dermal absorption has been demonstrated in both humans and animals. Regardless of the
exposure route, nickel is excreted in urine, hair, and sweat in both humans and animals. Nickel
is an essential element for maintaining health in animals and possibly humans. The most
prevalent effect of nickel in the general population is contact dermatitis. The respiratory system
is the major target organ following inhalation exposure. Effects in both humans and animals
include bronchitis, decreased lung capacity, asthmatic disease, and allergic responses. Other
target systems of nickel include the kidney and the immune system. Nickel refinery dust has
been classified as a Group A carcinogen (known carcinogen).
-------
Atmospheric nickel is emitted primarily in burning fuel oil and occurs predominantly as nickel
sulfate. Both wet and dry deposition of nickel aerosols occur. Nickel is constantly being
transferred between the environmental media through natural processes, such as weathering,
erosion, leaching, and runoff. Processes, such as complexation, precipitation/dissolution,
adsorption/desorption, and oxidation/reduction reactions, control the mobility of nickel in aquatic
media. There is no data indicating that water or soil microorganisms biotransform nickel. Some,
but not all, aquatic organisms are reported to bioaccumulate nickel.
Thallium
Pure thallium is a soft bluish-white metal that is widely distributed in trace amounts in Earth's
crust. In the pure form it is odorless and tasteless. Thallium exists in two states, thallous and
thallic. The thallous state is the more common and stable form, and thallous compounds are the
most likely form to which humans may be exposed. Thallium is most commonly used in
manufacturing electronic devices, switches, and closures and has limited use in the manufacture
of special glasses and certain medical procedures. Until 1972, thallium was used as a rat poison,
but was then banned due to its potential harm to humans. The chemical can enter the body
through all exposure routes. When swallowed, most of it is rapidly distributed to various parts of
the body, especially the kidney and the liver.
Thallium can affect the nervous system, the lungs, the heart, the liver, and the kidneys if large
amounts are ingested over a short time. Temporary hair loss, vomiting, and diarrhea also can
occur and death may result after exposure to large amounts of thallium (1 to 4 mg/kg/day) for
short periods. It can be fatal at a dose as low as one gram. Animal reproductive organs,
especially the testes, were damaged after small amounts of thallium-contaminated water were
drunk for two months. No studies were found on whether thallium can cause cancer to humans
or animals. EPA has assigned a classification of Group D (not classifiable for human
carcinogencity) to several thallium compounds. Thallium tends to sorb to soil and sediment and
may be bioconcentrated by organisms from water.
Zinc
Zinc is a metal found naturally hi air, soil, water, and food, and is an essential trace element
needed by the body. Zinc has many uses in industry in its pure form or mixed with other metals
as an alloy. It is absorbed after oral ingestion from all segments of the intestines, and zinc dust
may be absorbed through the lungs and to a limited extent, the skin. The metal-binding protein,
metallothionein, controls the intestinal transport of zinc and also prevents excess absorption.
Metallothionein binds zinc in intestinal mucosal cells, and the cells are sloughed off and excreted
when the system is saturated. High levels of calcium and phosphate in the intestines decrease
absorption of zinc, while the presence of protein enhances absorption.
Acute inhalation exposure to zinc oxide causes a syndrome known as "metal fume fever."
Clinical signs include cough, nasal irritation, decreased lung volume, and chest pain, and the
symptoms usually diminish in 24 to 48 hours. Oral ingestion of large amounts of zinc produces
-------
gastrointestinal distress, with burning and pain in the mouth and throat, and vomiting.
Individuals occupationally exposed to airborne zinc oxide developed lung-tissue damage in the
alveolar region.
In the environment, zinc tends to exist in the divalent oxidation state. Atmospheric zinc has not
been studied comprehensively, but the belief is that is exists sorbed to particulate matter.
Aquatic zinc is present in suspended and dissolved forms. It may also partition onto sediment,
suspended solids, hydrous iron, and manganese oxides, as well as sorbing to clay minerals and
organic material. Zinc is strongly sorbed in soils and bioaccumulates in fish, crustaceans, and
plants.
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APPENDIX B - FIGURES
\
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Brfdgcton Township
Bucks County
Figure 1
Site Location
-------
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» u i ir« E T o
• v-. .; •' } >/'• • '••SfeA -
•-•<""••'' --x ( r .'>•• «V--. •
K >'•' / \xL-•••"• m i
.
REFERENCE
POND
:?u x /
FIGURE 3
LOCAL LAND USE
BOARHEAO FARMS
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KflfUZ UTH COMC
mrfmi HUOUH
O "•• OVtWUWCN WMIIMIW KLL
"•-' OVCMUHOCtt/KMtOC* KMIIMIHG Ku
W-M WM.I.OI KOMtt WMtlMINC Mil.
Ow-U OUP KMOCI WNITIMIHO «u
ItSI fll LOUTIM
FIGURE 4
MONITORING TEST PIT
BOARHEAD FARMS
UPPER BLACK EDDY. PENNSYLVANIA
-------
o
MV*>Ct WAUH COumt
* *..,< * ft»OMtlOH*atUAf| tiltNl W (JriUA*..!.
c<«**tA*«»«A«*l m Win
Figures
EXISTING GROUND WATER
COLLECTION SYSTtM AND
DISTRIBUTION OF ORGANIC
AND INORGANIC CONTAMINATION
IN SUBSURFACE SOUS
FAflMS Hl*1
-------
-------
LEGEND
— SURFACE MICH COURSE
—• MOPCRFV MUNDAftr
• tl 1ST INC EXTRACTION «U 1. OCA 11 OX
mSTIINC (ttOUNOUTEII COLLECT ION
HOT SPOT 1
HOT SPOT SOIL
STAGING AND
TREATMENT AR
FIGURE 7
HOT SPOT REMOVAL AREAS
BOARHEAD FARMS
UPPER BLACK EDDY, PENNSYLVANIA
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APPENDIX C - TABLES
\
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Table 1
Areas of Investigation
Area 1
Area 2
Area 3
Area 4
Area 5
Area 6
Area?
PondS
Pond 9
Pond 10
Pond 1 1
Area 12
Unnamed
Creek
Groundwater
Large open field in the north-central part of the Site. Includes area on both
sides of the entrance road. This is area of ammonia release in 1976 and
where the presence of tanks, drums, and trailers has been documented.
Includes farmhouse, office, and stables. Evidence that tanks and chemicals
were stored in this area.
North of Area 1; tanks and other objects have been stored. Tanks from this
area were moved to Area 1 during RI activities.
Area closest to and just north of entrance road. Aerial photographs indicate
ground disturbance or excavation.
Cleared area just south of Area 1. Documented presence of tanks and other
objects in the area in 1970s. Includes an area containing burned oil filters.
Large area between ponds and Area 2. Presence of a fill area and standing
liquid noted in aerial photographs.
Area surrounding and including the operating Keystone Excavation
building.
Pond at east end of Area 1. Drainage from Area 1 enters the pond.
Small detention pond in southeast comer of the Site that receives drainage
from swamp.
Reportedly, lime was added to neutralize discharges of acidic surface water.
Pond just south of the Area 2 farmhouse. Standing liquid noted in aerial
photographs before the presence of the pond.
Large pond south of Area 5. High contaminant concentrations in surface
water and sediment measured during the Site investigation before
construction of the pond.
Swamp area east of large pond to Site boundary. Received drainage from
ferrous chloride spill. Formerly wooded wetland until disturbed by Site
discharges.
Unnamed tributary of the Delaware River (unnamed creek) that receives
surface runoff from the Site through five culverts that flow beneath Lonely
Cottage Road.
Aquifers) beneath and downgradient of the Site that are affected by Site
activities.
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Dieldrin
,<-Dichtofopnenol
•Nitrophenol
Naphthalene
1
1
Volatile Organic Compound*
* contaminant exceeded the maximum contaminant level (MCL).
= contaminant exceeded the state HAL; used where MCL does not exist.
WOC97028000;
PAGE20F2
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Preliminary Remediation Goals for Groundwater
Chemical
Lead
Nickel
— ^™^^^^»^^^™™^^^^^™
Preliminary
Remediation Goal
(mf/L)
0.006
0.004
0.005
0.100
1.000
0.005
0.100
0.002
Pesticide*
Aldrin
Dieldrin
Senfeolatife Organic Compound*
1 ,2-Dichlorobenzene
1,4-Dichlorobenzene
2,4-DichloTOphenol
bis(2-ethylhexyl)Phthalaie
Naphthalene
2.00E-06
0.0002
2.00E-06
0.600
0.075
0.020
0.006
0.020
Volatile Orcank Compound*
1,1,1 -Trichlorocthane
1 , 1 ,2-Trichloroethane
1,1-Dichloroethene
1 ,2-Dichloroethane
1,2-Dichloroethene (Total)*
1 ,2-Dichloropropane
Benzene
Carbon Tetrachioride
cis- 1 .2-dicUorDethenek
Ethylbenzen*
Methylene Chloride
Tetrachloroethene
Toluene
trans- 1 ,2-dichloroethene*
Trichioroethene
Vinyl Chloride
0.200
0.005
0.007
0.005
o.or
0.005
0.005
0.005
0.070
0.700
0.005
0.005
1.000
0.100
0.005
0.002
Standard*
MCL
MCL
MCL
MCL
HAL
HAL
MCL
MCL
HAL
MCL
HAL
MCL
MCL
HAL
MCL
HAL
MCL
MCL
MCL
MCL
MCL
MCL
MCL
MCL
MCL
MCL
MCL
MCL
MCL
MCL
MCL
MCL
' MCL=Primary MCL from SOW A; HAL=PA Act 2 when primary MCL does not exist.
* COPC is listed as 1 ,2-DCE and xylenes otrfy; various isomers were not differentiated.
c USEPA MCL value is for cis- 1 ,2-DCE: a USEPA MCL for (total) 1 ,2-DCE is not available.
WDC9702900II .DOC/l/seb
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Table 4
Prelimuiary Remediation Goals for Soil
Boarnead Farma
Preliminary*
Remediation Goal
Chemical
Chemicals (
SemlvolatUe Organic Com
l^-Dichlorobenzene
1.4-Dichlorobenzepe
l.l.l-Trichlomethaiv.
Ethylbenzene
Tetrachloroethene
Trichloroethene
Xylenes (Total)
1.1.2-Trichloroethane
1.1-Dichloroethene
1.2-Dichloroe thane
Pichloroethene (Total)
Carbon Tetrachioride
Chlorobenzene
cis-1,2-dichlorDethene
Methylene Chloride
' I I -^"MIBM^BmMB^^^^^^^^^MjH
trans-1.2-dichIoroctnene
Vinyl Chloride
Notes:
I 'Established by site-specific PRG modeling using MULTIMED.
I BL—K, values derived from site-specific batch leach tests.
LD—K, derived from literature.
I K, values were calculated using the organic carbon partitioning function obtained from the
tOOn CDA/c/mst nnmi t\ i •- ._
PRO values rounded to three significant fi
• oane om te
'l990> EPA/54(V2-9(V01 1 ). and site-specific measurements of total
WDC9702900l6.DOO2/$«b
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Area-Specific Exceedances of MUL1
for Coalamiiiaoti ol
Bo
Beryllium
Cadmium
Chromium, lota)
Lead
TableS
IMED-Based Preliminary D»
r Potential Concern in Subsurl
•rbead Farms RI/FS
mediation Goals (PRGs)
aceSoil . '
Area Where PRG is Exceeded
I
X
X
X
2
X
X
5/6
South
5/6
North
7
Wetland*
3
Wetlands
12
Detected
Minimum
Detected
M'tlmum
Inorganic Cbentkab (mi/kg)
X
X
X
X
X
X
X
0.12
0.25
44.2
1.5
1,200
423
2,280
11,800
Detected
Average
10.9
21.2
521.4
129.6
Semi volatile Organic Compounds tylf/kf)
2-Melhylnapthelene
bis-2-(elhylhexyl)ptuhalalc
X
X
Volatile Organic Compound
U.I-Trichloroelhane
Benzene
Teirachloroelhene
Toluene
Trichloroelhene
X
X
X
X
X
X
X
X
X
X
X
X
X
X
b(Mt/kg)
X
X
X
25
42
1
1.9
2
1
1
Note: PRGs developed using the MULTIMEO fate-and-lransport modeling code.
72,000
100.000
94,000
113
15,000
870,000
2,200.000
5.139
5^474
6.282
24
1,088
30,898
35.615
WDPMtftKKKMOOC/.Vftb
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Reside
Well No.
RW-01
RW-01
1 RW-02
1 RW-05
1 RW-10
1 RW-10
1 RW-10
1 RW-10
RW-13
RW-14
RW-16
RW-20
RW-21
RW-23
RW-23
RW-25
RW-28
I1 RW-31
RW-32
RW-32
RW-34
RW-34
RW-35
. RW-35
RW-35
RW-35
RW-52
RW-54
RW-54
RW-61
RW-64
RW-64
RW-86
Table <
sntial Wells with MCL Exceedan
Boarhead Fan
^^^^^^^^^^^^^^^^^^^^^^^^"^^^^^^^•^^^••••••••••i
Chemical
Antimony
bis(2-ethylhexyl)phthaiate
Fentachlorophenol
Pentachlorophenol
1,1,1-Trichloroethane
Chromium
Fetrachloroethene
Trichloroethene
Fhalhum
Antimony
Antimony
Pentachlorophenol
bis(2-emylhexyl)phthalate
Thallium
bis(2-ethylhexyl)phthalate
bis(2-ethylhexyl)phthalate
bis(2-ethylhexyl)phthalate
Chromium
Nickel
bis(2-ethylhexyl)phthalate
Cadmium
is(2-ethylhexyl)phthalate
Cadmium
Chromium
Nickel
3ia<2-ethylhexyl)phthalate
3ia<2-ethylhexyl)phthalate
rhaUium
Antimony
is(2-ethylhexyl)phthalate
etrachloroethene
fhallium
*: —
ces (data compile
nsRI/FS
•••MMMMMMM
Concentration
(M8/L)
22.4*
12
.— __
1
2
520
155
5
2800
2.4»
63*
17.8»
13.2*
2
16
2.1*
6
6
14
648
311
6
6.4*
16
5.1*
446
218
74
72
2.2*
14*
26
12
2.7*
d through
Data
Qualifier
••MMMMMiaMM^^
J
J
J
J
KJ
J
J
JL
J
K
K
JL
JL
JL
Note:
Only pimary MCLs were used. ~
PMCLs for inorganics that only were exceeded during one sampling event.
12/95)
MCL
(HS/L)
6
6
1
1
200
100
5
5
2
6
15
6
1
6
2
6
6
6
100
100
6
5
6
5
100
100
6
6
2
6
6
5
2
WOC97Q2a0006.DOC/1/Km
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Table 7
SUMMARY OF THE COrCs IDENTIFIED THROUGH THE BOARHEAD FARMS HUMAN HEALTH RA
Pond Surface
Surface Soil • • Shallow Crou«dw»t«r , Pond Sediment Water
Cadmium
Chromium
Arsenic
Beryllium
Copper
thallium
Zinc
bis(2-Eihylhexyl)phlhalaie
n-Niirosodipropy famine
Aluminum Chloroform 2,4-Dinitrophcnol
Arsenic . 1,2-Dichlorobenzene 2-Methylnaphihalene
Barium 1.4-Dichlorobenzcnc 4-Methylphenol
Beryllium 1,1-Oichloroethane Naphthalene
Cadmium 1,2-Dichlorocihane Nitrobenzene
Chromium 1,1-Dichloroethene 2-Nilrophcnol
Cobalt 1,2-Dichloroeinene 1,2,4-Trichlorobenzene
Copper 1,2-Dichloropropane 2.4,6-Trichlorophenol
Cyanide Eihylbenzenc BHC-alpha
Lead Methylenc chloride BHC-delta
Manganese Methyl isobulyl ketone Heptachlor
Nickel 1,1,2,2-Tetrachloroeihane
Silver Tetrachloroclliene
Vanadium Toluene
Thallium 1,1,1-Trichloroemane
Zinc 1,1,2-Trichloroelhanc
Benzene Trichlorocthenc
Bromodichtoromethane Vinyl chloride
2-Buianone Xylenes
Carbon letrachloride bis(2-Chloroelhyl)clher
Chlorobenzenc 2,4-Dichlorophcnol
Arsenic
Beryllium
Chromium
Nickel
Chromium
Manganese
PIIUI':\I05586\RJRI\OI5.DOC
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: Table 8
TOX.CITY VALUES USED IN THE HUHAN HEALTH RISK ASSESSMEKT
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Table 9
Human Health Risks at the Hoarhead Farms Site
Group of Individuals
Onsite Residents Consuming
I Groundwater from Onsite Residential
Well
Onsite Residents Consuming the most
Contaminated Groundwater
I Onsite
Onsite Residents on Public Water Supply
Offsite Residents Consuming
Groundwater Downgradient from Site
Onsite Workers Consuming die most
Contaminated Groundwater Onsite
Onsite Workers on Public Water Supply
Recreational Site Users - Wooded Upland
[Areas
Recreational Site Users - Wetlands
Recreational Site Users - Ponds
Recreational Site Users - Pond Fish
Consumption
! Recreational Offsite Users - Culvert and
i Creek
Recreational Offsite Users - Culvert and
Creek Fish Consumption
Cancer Risk
^^M
1.3E-03
3.5E-01
4.1E-05
5.0E-04
3.3E-02
4.3E-06
8.4E-09
Hazard Index
1.3E-06
5.8E-05
52
17,000
0.24
7.6
1800
NCP determines unacceptable risks exist when greater than:
Cancer Risk: 1 .OE -04 Hazard Index: 1.0
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TABLE 10 - SUMMARY OF ALTERNATIVES
Alternative 1
No Action
Alternative 2
Continued Maintenance and Monitoring of the Existing Groundwater Interceptor Trench,
Treatment facility, and residential Well GAG Filters; Institutional Controls
Alternative^
Soil Excavation, Multilayer Cap; Excavation and Offsite Disposal of Buried Drums;
Groundwater Extraction, Metals Precipitation, and Air Stripping; Institutional Controls and
Monitoring; and Residential Water Treatment
Alternative 4
Soil Excavation and Stabilization/Solidification; Excavation and Offsite Disposal of Buried
Drums; Groundwater Extraction, Metals Precipitation, and Air Stripping; Institutional Controls
and Monitoring; and Residential Water Treatment
Alternative 5
Excavation of Soil and Placement in Onsite Landfill; Excavation and Offsite Disposal of Buried
Drums; Groundwater Extraction, Metals Precipitation, and Air Stripping; Institutional Controls
and Monitoring; and Residential Water Treatment
Alternative 6
Soil Aeration and Treatment of VOC Hot Spots; Excavation and Offsite Disposal of Buried
Drums; Groundwater Extraction, Metals Precipitation, and Air Stripping; Institutional Controls
and Monitoring; and Residential Water Treatment
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PART III
RESPONSIVENESS SUMMARY FOR THE PROPOSED REMEDIAL ACTION PLAN
AT THE
BOARHEAD FARMS SUPERFUND SITE
BRIDGETON TOWNSHIP, PA
Public Comment Period: January 5,1998 - April 5 ,1998
\
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RESPONSIVENESS SUMMARY
BOARHEAD FARMS SITE
BRIDGETON TOWNSHIP, BUCKS COUNTY, PENNSYLVANIA
This community relations responsiveness summary is divided into the following sections:
Overview; This section discusses EPA's preferred alternative for remedial action.
Background; This section provides a brief history of community interest and concerns raised
during remedial planning at the Boarhead Farms Site.
Parti: This section provides a summary of issues and concerns raised by the local
community at the public meeting on January 14,1998. "Local community"
includes local homeowners, businesses, the municipality, and potentially
responsible parties (PRPs).
Part II: This section provides a summary of commentors' issues received via electronic
mail or written letters throughout the comment period.
OVERVIEW
On January 5,1998, EPA published its preferred alternative for the Boarhead Farms Site, located
in Bridgeton Township, Bucks County, Pennsylvania and announced the public comment period.
EPA screened six possible alternatives to remediate groundwater and soil contamination, giving
consideration to nine key evaluation criteria found in the NCP:
• Threshold criteria, including
Overall protection of human health and the environment
— Compliance with Federal and state environmental laws
• Balancing criteria, including
— Long-term effectiveness
— Short-term effectiveness
— Reduction of mobility, toxicity, or volume
— Ability to implement
— Cost, and
• Modifying criteria, including
State acceptance, and
Community acceptance
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The preferred alternative, Alternative 6, includes the following
measures:
• Soil Aeration and Treatment of VOC Hot Spots: Mechanical aeration of soil hot spot
areas to remove high levels of VOCs (primarily TCE and benzene) in a temporary onsite
treatment building equipped with carbon filters
• Excavation and Offsite Disposal of Buried Drums: Excavation and offsite disposal of
buried drums to reduce the potential for continued migration of contaminants to the soil
and groundwater as well as to reduce exposure risk
• Groundwater Extraction, Metals Precipitation, and Air Stripping: Continued
extraction and treatment of VOCs in groundwater via the existing interception trench and
air stripping treatment system and addition of a metals precipitation unit to remove
inorganics to reduce contaminants in the groundwater to below Maximum Contaminant
Levels (MCLs)
• Installation of Additional Monitoring Wells: Installation of additional (specific number
to be determined during remedial design) monitoring wells to monitor the effectiveness
of the remedial action. These wells will be placed in areas along the perimeter of the Site
to permit monitoring of migration, if any, of contaminated groundwater
• Institutional Controls and Monitoring: Implementation of institutional controls to
protect the integrity of the remedial action components and the previously installed soil
cover to ensure continued protectiveness of the remedy.
• Residential Water Treatment: Continued maintenance of the granular activated carbon
(GAC) filters that were installed on affected residential water wells in the surrounding
area to prevent exposure to contaminated groundwater from the Site
• Phytoremediation: Performance of treatability studies in the main former disposal areas
of the Site to determine whether phytoremediation is a viable treatment technique to aid
in the removal of VOC and metals contamination in the groundwater.
BACKGROUND
To obtain public input on the Proposed Remedial Action Plan (Proposed Plan or PRAP), EPA
held a public comment period from January 5,1998, to April 5,1998. In addition, EPA held a
public meeting on January 14,1998, to explain the preferred alternative and to answer questions.
Local residents and officials, news media representatives, representatives from EPA, and
representatives from companies interested hi Site activities and cleanup decisions attended the
meeting.
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EPA notified the public of the January 14, 1998, public meeting and announced the public
comment period in a display ad placed in the January 5 and 9, 1998, editions of The Intelligencer
Record and The Morning Call, and the January 8,1998 edition of the Delaware Valley News.
After the January 14 public meeting, EPA granted a request to extend the public comment period -
one month to March 6,1998. EPA announced the extension in the January 29,1998 editions of
The Intelligencer Record, The Morning Call, and the Delaware Valley News. At the close of the
March 6,1998 extension, an additional request was made for another 30-day extension. EPA
granted the request and the comment period, lasting a total of 90 days, closed on April 5,1998.
In addition, EPA placed copies of the Proposed Plan in the Site information repository at the
Bucks County Library Center. The repository contains the Administrative Record supporting
selection of the Remedial Action including the Remedial Investigation, the Baseline Risk
Assessment, the Ecological Risk Assessment, the Feasibility Study, the PRAP, and other relevant
documents upon which EPA relied in selecting the Site remedy.
EPA also prepared a fact sheet and distributed it to individuals in attendance at the public
meeting. The fact sheet included a summary of the Proposed Plan.
Part I; Summary of Issues and Concerns Raised at the Public Meeting
This section provides a summary of issues and concerns raised by the local community at the
public meeting held on January 14,1998. The comments can be grouped into six categories:
A. Remedial Alternative Preferences
B. Current Site Conditions
C. Human Health Concerns
D. Funding Issues
E. Schedule
F. Public Participation Process
The questions, comments, and responses are summarized below.
A. Remedial Alternative Preferences
1. A resident recommended that Alternative 5 be implemented at the Site since it includes
removal of all contaminated soil, not just the soil in the highly contaminated "hot spot"
areas.
EPA Response: Alternative 5 proposes the creation of an onsite landfill. Landfills are
often implemented at sites to prevent migration of hazardous substances offsite. EPA
gave a great deal of consideration to Alternative 5 as a proposed remedy for this Site.
However, Alternative 5 would not remove all contamination from the Site, but rather
would place all contaminated soils in a central location, the onsite landfill (see the
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f 1^ ^ Evaluation of Alternatives, Section IX of the ROD). In addition, an onsite
landfill does not seem to be favorable to residents in the surrounding areas since it is
expected that there would be some migration of contamination down from the landfill and
along the surficial aquifer. Therefore the landfill alternative would not provide any
additional benefit over the proposed remedy. The proposed remedy would remove from
the Site the most contaminated soils, thus eliminating the possibility of any exposure to
such contaminants by human and environmental receptors.
2. A resident recommended the selection of Alternative 4 since it appears to address all
areas of contamination.
EPA Response: Alternative 4 proposes soil excavation and onsite solidification. As
discussed in Section IX of the ROD (Comparative Evaluation of Alternatives),
stabilization is the most expensive alternative proposed and does not present any
environmental advantage over the selected alternative. Stabilization technology works
well with certain types of wastes, particularly heavy metals. Recent literature on the
effectiveness of stabilization on VOC contaminated soils shows that this approach is not
always effective and the VOCs continue to leach from the stabilized areas. Therefore,
while stabilization has been shown to be protective with respect to metals contaminated
soils, EPA believes that this alternative may not be as protective of the community with
respect to the VOC contamination. EPA believes that Alternative 6 will accomplish
levels of protection which will be acceptable. It is important to note that when soils are
solidified/stabilized, the contaminants remain onsite in a central location.
3. Several residents expressed concern about the contaminated soil remaining on the Site
after implementation of Alternative 6. They feel that there is a potential for rain water to
infiltrate the soil and move contamination from the soil to the groundwater below.
EPA Response: Offsite disposal was one of the first remedial processes considered. EPA
agrees that the acidic rainfall in the area will infiltrate the soil and move contamination
out; in fact, that process is an integral part of the remedy. The existing interceptor
trench will collect all groundwater flowing from upgradient areas (where the
contaminated soils are located) and direct these flows to the onsite treatment system.
With the addition of a metals precipitation unit, all VOCs and metals of concern will be
removed through this groundwater treatment system.
4. A Bridgeton Township official asked how Alternative 6 would address groundwater
contamination, particularly trichloroethylene (TCE), detected in upgradient wells along
Deer Lane.
EPA Response: Deer Lane is upgradient from the Site. The contaminants detected in the
upgradient wells along Deer Lane are believed to be nonsite related since those
contaminants were not found at the Boarhead Site. Since the wetlands are situated
4
-------
between the Site and these well locations, and the wetlands act as a natural filtration
system for VOCs, the contaminants in the upgradient wells will not impact the Site.
5. A Bridgeton Township official expressed concern over EPA's decision not to implement
the U.S. Department of Interior Fish and Wildlife Service's recommendations dated
January 26, 1996, for Site cleanup.
/
EPA Response: U.S. Department of Interior Fish and Wildlife Service and EPA reached a
joint recommendation based on a follow-up study (included in the Administrative Record)
which followed from the recommendations presented in the January 26, 1996 letter.
According to subsequent documents all contained in the Administrative Record, the
recommendations of January 26, 1996 were changed and all risk and ecological issues
have been addressed.
6. A member of the Bridgeton Township Planning Commission asked how Alternative 6
will address groundwater contamination in the aquifer beneath the Site.
EPA Response: Alternative 6 calls for continued use of the existing groundwater
extraction and treatment system, with an upgrade to include metals precipitation. The
groundwater extraction system captures groundwater in the shallow and intermediate
aquifers. The shallow groundwater system is composed of the upper 40-50 feet of
weathered and moderately fractured rock, and most of the groundwater flow occurs in
this system. The majority of groundwater in the shallow system is captured by the
extraction trench or is captured by the extraction wells. The shallow groundwater system
grades into the intermediate groundwater system. The intermediate zone extends to
approximately 500 feet below the ground surface, and has only minor amounts of
fractures and associated groundwater. No fractures were identified below 100 feet. The
intermediate groundwater system is considered an aquatard. Four hundred feet of
unfractured diabase rock separates site groundwater from the deep groundwater system.
The deep groundwater system is composed of fractured Triassic age sandstone and shale.
Most residential wells in the area get their water from the deep groundwater system.
EPA does not believe that the deep aquifer has been affected by contaminants from the
Site.
7. A member of the Bridgeton Planning Commission expressed concern that Alternative 6
does not address the source of the metals contamination.
EPA Response: EPA conducted a large scale sampling of various residences in the area
of the Site during the remedial investigation. Analyses of these sampling results showed
elevated levels of various substances including some metals. Analytical results such as
these are relatively common and are often encountered in "clean " areas as well as in
areas near Superfund sites. Precipitation at the Site will wash the residual soil
contamination (both metals and VOCs) into the shallow groundwater. The addition of
-------
metals treatment to the existing groundwater treatment plant will result in these metals
being treated and removed through the interceptor trench system. Both EPA and PADEP
have reviewed this data and feel that the elevated metals levels found in the otherwise
uncontaminaied areas around the Site are likely from the diabase rock formation which
underlies this area.
8. A resident asked how long institutional controls would be in effect under Alternative 6
and what agency enforces them.
EPA Response: Institutional controls will remain in effect as long as it is determined
they are needed to protect the integrity of the remediation systems at the Site or until the
Site no longer poses a risk or potential risk to the community. Enforcement of
institutional controls is complex and depends on the manner in which such controls are
implemented. Details regarding the form of institutional controls will be developed
during implementation of the selected remedy. Both the Commonwealth and local
authorities may impose additional controls and would be responsible for enforcing them.
9. A resident recommended that EPA install an interceptor trench north of the Site to stop
groundwater flow in a northerly direction since the contaminated groundwater may
endanger the residents in that area.
EPA Response: Installing an interceptor trench north of the Site would destroy the
wooded wetlands in that area. It is EPA's belief that the current ecosystem in the
wetlands is both containing and removing the high levels ofTCE contamination in that
area. If the wetlands were to be destroyed in order to construct an additional
interceptor trench, much of the natural remediation that has been taking place would be
reversed. EPA believes that, at best, an extended interceptor trench would be no more
effective than the existing ecosystem. Construction of an additional interceptor trench
would be detrimental to the wetland area and may also pose additional risks to people
residing in this area since the existing ecosystem would be diminished.
10. One resident expressed concern that there is no surface water monitoring of the streams
and ponds located at or near the Site. Monitoring would help determine if the underlying
groundwater is contaminating these surface water bodies.
EPA Response: EPA has performed extensive monitoring of the surface streams and
ponds both on the Site and in the adjacent community. Analyses of these data have
satisfied EPA that the underlying groundwater is not contaminating these surface water
bodies. These concentrations were incorporated into the Site-specific human health risk
assessment. None of the low level contaminants found in the surface water exceeded the
values for the Site-specific human health assessment.
-------
1 I. v-fiic iGsiuenr acuv»ri *«>^A*U.— ^.L _ j . .
selected remedy
B. Current Site Conditions
1. One resident asked how many drums are still buried at the Site.
H-~^^
Following the removal actions that took place in 1992 and 1993, EPA conducted a
magnetometer survey of the Site and found approximately 20 additional anomalies
Anomalies can represent a variety of metal objects so EPA is noT™a™™att
ZZ , C°nSiS'°{drums' "» anomaly locations will be farther investigated during
implementation of the remedy and any drums identified will be disposed ofoffsite.
2. ABrid—T*^^^
'.: During the removal actions in 1992 and 1993, EPA identified drums
--•-»••* -dioactive waste with labels from General Machine Corporation General
Machine was notified and proceeded, atthattime, to remove all radLcTelaXesthat
werecletecbedfrom the Site. Subsequent surveys conducted by EPA have not found
evidence of any other radioactive wastes at this Site.
A resident asked for a description of the intermediate groundwater system and whether
the existing interceptor trench collects contaminated groundwater from this system
dalSh^nr^!nteTnef^^ V^™ " defi»ed<" ^ing within the deep-
diabase bedrock, below 40 feet. The intermediate groundwater flow is through a
network of very minor and limited fractures existing in the upper portion of this
formation (approximately JO -40 below ground surface). Although there is indication
that groundwater may be capable of flowing from the shallow system to the fractures of
the intermediate system, the fractures are limited in extent and hence the depth to which
groundwater may flow is limited In addition, hydraulic interconnection between the two
systems IS more likely at the edges of the diabase sheet which extends well past the
boundaries of the Site and the surrounding residences. EPA has installed extraction
wells (EC wells) in areas where the groundwater does not flow into the interception
-------
trench. Some of these EC wells are directly in the intermediate groundwater system and
collect groundwater from the fractures described above. The groundwater collected in
the EC \vells is pumped to the treatment system, treated and discharged.
4. A resident asked whether contamination was detected in the intermediate groundwater
system.
EPA Response: Low levels of contaminants -were detected in a few of the intermediate
groundwater wells. Water collected in these wells is pumped to the treatment system for
treatment and discharge. The quantity of groundwater in this system is extremely small.
5. Several residents expressed concern about the potential that contamination in the
intermediate groundwater system will eventually reach residential wells at the Site.
EPA Response: The intermediate groundwater system acts primarily as an aquatard
(restrictingflow movement). Very little, if any, groundwater passes through it. Even if
groundwater flow in the intermediate system did increase, there would be negligible
chance for the Site contamination to impact residential wells by this pathway.
6. A Bridgeton Township official asked how the interceptor trench collects contaminants
detected in groundwater downgradient of the Site.
EPA Response: The extraction wells and interceptor trench capture contaminated
groundwater downgradient from the contamination located onsite but do not treat
groundwater located downgradient from the trench location. The wetland areas
downgradient from the interceptor trench are only minimally contaminated (with the
exception of the TCE hot spot area) and the contamination is being addressed through
natural remediation. In addition, the selected remedy includes periodic resampling of the
monitoring wells downgradient of the Site boundary. If contaminants are found at
elevated levels, steps will be taken to ensure that any such contaminants are removed
before they reach the surrounding community.
7. A resident asked how long the existing interceptor trench has been operational.
EPA Response: The existing groundwater interceptor trench has been collecting water
flowing from the Site since October 1997.
8. A resident asked whether the levels of contamination in the groundwater collected in the
interceptor trench have decreased since its inception.
EPA Response: Since EPA has been collecting data from this interceptor trench for a
relatively short period of time, it is difficult to give an accurate answer to this question.
Data collected to date indicate that the levels of contamination in the interceptor trench
8
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have remained relatively constant since the start up in October 1997. The efficiency for
removal of VOCs through the treatment system is in excess of 99%. *
A resident asked whether the levels of contaminants detected in the monitoring wells at
the Site have decreased since the removal of drums and contaminated material through
nnor removal antirme uuwugu
9.
prior removal actions
EPA Response: There are a number of monitoring wells in and around the Site which
have shown little or no contamination. Some of these wells were installed to provide
background information; others as sentinel/monitoring wells, to provide early warning
should contamination begin to migrate towards nearby residences. EPA's data from
those monitoring wells where contamination was initially detected show that overall, the
amount of contamination detected in the groundwater has decreased since EPA's drum
removal operation.
10. A resident asked whether the tanker truck that was buried under the big pond in the
1970's was located and removed from the Site.
EPA Response: EPA has conducted extensive "magnetic anomaly" surveys of the entire
property and, to-date, has excavated, and removed in excess of 2,500 drums. No buried
tanker trucks have been found. In addition, the large pond where the truck was thought
to be buried was drained as part of the removal action, and a number of drums were also
removed from the underlying soil. No evidence of any buried tanker trucks) was found.
Part of the selected remedy includesfurther excavations of the Site where magnetic
anomalies have been observed.
11. A resident asked for a quantification of groundwater that migrates offsite.
EPA Response: Although EPA has not calculated the volume of groundwater that
migrates from the Site, based on Site hydrogeology and groundwater pathways EPA is
certain that all onsite groundwater migrates offsite. This occurs at different rates
depending on the aquifer medium. The fastest flow occurs within the sand unit lying on
top of the bedrock. Flow within this unit may be as high as 14 feet per day. Flows within
the fractured bedrock are much slower and are generally much less than a foot per day.
The highest concentrations of contaminated groundwater are captured by the
groundwater extraction system. Lower concentrations of contaminated groundwater are
remediated by natural mechanisms within the wetland area.
12. A resident asked about the potential for groundwater contamination to migrate offsite
if there has been no historical reports of offsite migration.
EPA Response: EPA has studied the area around the Site, including the groundwater
flow patterns, and determined that there is potential for contamination located on the Site
-------
to migrate offsite. Contamination has been measured in the groundwater onsite and in
low levels leaving the Boarhead property. Currently, the existing interceptor trench and
groundwater treatment system (constructed as part of a separate removal action) collect
a large amount of the onsite groundwater and treat it onsite, thus reducing the potential
for migration of groundwater offsite. However, EPA has installed a series of monitoring
wells along the perimeter of the Site as a precaution and can determine if contaminated
groundwater begins to move offsite.
C. Human Health Concerns
1. A resident asked about the distinction between risks to onsite residents and risks to
residents living near the Site.
EPA Response: As both the Proposed Plan and this ROD present in table form, the risks
to onsite residents are much greater than the risks to neighboring residents. Risk, as
presented in EPA documents, relates only to the real or potential exposure of persons to
substances present onsite. High levels of contamination were found in the onsite
residential well as well as in soils near the farmhouse. The levels found in the residential
wells neighboring the Boarhead property were minimal to none.
2. A resident asked for an explanation of EPA's terminology of "maximum cancer risk"
(e.g., 1.3E-03 for onsite residents consuming groundwater from onsite residential wells).
EPA Response: The value 1.3E-03 means that, based on statistical data for onsite
residents drinking water from the most contaminated onsite well, there would be an
expected increase above the normal rate in the indices of cancer in this group ofdn
additional 1.3 cancers per 1,000 persons. The National Oil and Hazardous Substances
Pollution Contingency Plan (NCP) established acceptable levels of carcinogenic risk for
Superjund sites ranging from one excess cancer case per 10,000 persons exposed to one
excess cancer case per one million persons exposed. This translates to a risk range of
between one in 10,000 and one in one million additional cancer cases. Expressed as
scientific notation, this risk range is between 1. OE-04 and 1. OE-06. Remedial action is
warranted at a site when the calculated cancer risk level exceeds 1. OE-04. However,
since EPA's cleanup goal is generally to reduce the risk of I. OE-06 or less, EPA often
takes action where the risk is within the range between 1. OE-04 and 1. OE-06.
The cancer risk ofl.3E-0.3 (1 additional cancer occurrence in a population of 1300) for
onsite residents consuming groundwater from the Site is above EPA's determined
maximum cancer risk. EPA's goal in cleaning up sites is to reduce the risk posed by site
contaminants to less than one in a million or 1E-06.
10
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3. A resident asked for a comparison of Site risks to normal risks of living elsewhere.
EPA Response: The Baseline Human Health Risk Assessment (BLRA) conducted by EPA
provides all risk information regarding both onsite and offsite residents. For the
purposes of EPA 's Site assessment, risk is defined as the potential increase in the number
of cancer incidents due to Site contamination. Since the cancer risks associated with
living elsewhere are impacted by numerous environmental conditions and personal
decisions, EPA cannot make a determination regarding the difference in cancer risk
associated with living in the vicinity ofBoarhead Farms and living elsewhere. However,
as is described in both the Feasibility Study and the Proposed Plan, EPA has determined
that risks are much greater to onsite residents drinking and using onsite well water than
to those living in the vicinity of the Site.
4. A resident asked whether the cancer risk to residents living near the Site will reduce to
zero once the preferred alternative is implemented.
EPA Response: Cancer risk arises from both environmental conditions and personal
decisions (e.g., intentional exposure to tobacco products). The selected remedial action
obviously will not address risks presented through personal choice and which are
unrelated to Site contamination. EPA's goal is to reduce the risk of additional cancer
incidents from contaminants at the Site to less than one in a million.
5. A resident expressed concern about protection of human health that Alternative 6 would
provide once it was implemented.
EPA Response: Soil aeration and treatment ofTCE and benzene soil hot spots called for
in the selected remedy will reduce the risk of exposure to high levels of contamination in
the hot spot areas. In addition, soil aeration will eliminate the possibility ofTCE and
benzene leaching into the groundwater from the hot spot soils.
Excavation and offsite disposal of the remaining buried drums and associated soils will
reduce to acceptable levels the risk of the contaminants associated with the drums
leaching into the groundwater or further contaminating the surrounding soils. Filling in
these excavated areas will reduce the potential of future exposure to contaminated soils
through ingestion and direct contact.
Groundwater extraction, metals precipitation, and air stripping through upgrading the
existing groundwater treatment facility will reduce the potential of contaminated
groundwater moving offsite. The upgraded system will remove VOC and metals
contamination from all groundwater flowing into the interceptor trench and extraction
wells. This will reduce the risks of exposure through inhalation, ingestion and dermal
contact to offsite residents.
11
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Institutional controls and monitoring will reduce the possibility of further exposure to
contaminated soils, further consumption of contaminated groundwater, and further
ingestion of contaminated fish from the culverts and creeks. EPA believes that the full
implementation of the selected remedy will reduce the site related risks to the community
to less than one in a million or IE-06.
D. Funding Issues
1. A resident was concerned about EPA having adequate funding to perform Alternative
6.
EPA Response: EPA will first seek to have the Potentially Responsible Parties (PRPs)
complete this remedial action. Shortly after the issuance of this Record of Decision
(ROD), EPA will initiate a process for negotiations to commence with the PRPs to
conduct the cleanup activities. Should the negotiations fail to produce an agreement,
EPA -will consider other enforcement and/or funding options which include, among
others, ordering the PRPs to implement the remedy or using federal funds to implement
the remedy.
E. Schedule
1. A resident asked how long it would take to implement Alternative 6.
EPA Response: EPA expects that the design of the remedy will begin in 1999 and the
construction may begin in 2000. EPA estimates that it will take between 18 and 24
months to complete the construction of the remedial components.
F. Public Participation Process
1. A property owner who resides elsewhere commented that EPA did not notify him of
the public meeting. He stated that, hi the past, he had been notified of meetings via direct
mailing.
EPA Response: In this case, the property owner had been on a mailing list that had been
deleted through unforeseen circumstances. EPA produced a new mailing list, identifying
addresses within a certain radius of the Site. The property owner in question has been
added to the new mailing list.
2. A resident requested that the public comment period be extended to provide adequate
time for review of relevant Site documents.
EPA Response: EPA extended the comment period to a total of 90 days. The first
extension of 30 days was granted in January 1998 and announced at the public meeting
12
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on January 14, 1998. The second extension was granted after receiving requests from
the Bridgeton Township Supervisors and was announced on March 6, 1998. The
comment period officially closed on April 5, 1998. Since EPA believes that there has
been an extensive public comment period, EPA does not intend to reopen the comment
period at this time.
II; Summary of Comments and Questions Received in Writing During the
Public Comment Period
This section provides a summary of commentors' issues received via electronic mail or written
letters throughout the comment period. The following specific comments are addressed:
A. Comments of Brenda S. Schneider
B. Comments of Debi Slatkin
C. Comments of the Bridgeton Township Planning Commission
D. Comments of Jonathan C. Rolleri
E. Comments of Upper Black Eddy Historic Preservation Society
F. Comments of Wegard D. Holby
G. Comments of Larry Schultz
H. Comments of Bridgeton Township Supervisors
I. Comments of Lawler, Matusky & Skelly Engineers, LLP (LMS) on behalf of
the Boarhead Farms PRP Group
A. Comments of Brenda S.Schneider
In a one-page letter dated January 23,1998, Brenda S. Schneider, a resident of Upper
Black Eddy, submitted comments regarding the Proposed Plan and the remediation
process for the Boarhead Farms Site.
1. Concern was expressed that the remedial action at the Site is an opportunity to do away
with all presently contaminated and/or uncontaminated wells in the affected vicinity of
the Site, forcing residents to use city water and raise taxes.
EPA Response: The selected remedial action is intended to protect human health and the
environment from the contamination at the Boarhead Farms Site, EPA has determined
that residents living in the vicinity of the Site currently are not at risk from the
contaminants present at the Site; therefore, the alternative of placing surrounding
residents on public water was not considered in the Feasibility Study nor the Proposed
Plan and is not a part of this Record of Decision.
2. Who makes the final decision on which "Alternative Plan" is chosen and why isn't the
Proposed Plan more specific.
13
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EPA Response: EPA makes the final decision on which alternative will be chosen/or
implementation at the Site. EPA seeks concurrence from the Pennsylvania Department of
Environmental Protection (PADEP) and requests comments from the public to ensure
that all concerns on the proposed alternative are addressed. Comments from the public,
as well as from other agencies, play a large role in the decision process.
The Proposed Plan serves to provide a summary of past actions and current conditions at
the Site as well as to explain the process used by EPA to select a preferred alternative
from among several alternatives developed in the Feasibility Study. The Proposed Plan
contains sufficient detail to enable the public to engage in meaningful participation as
required by the Superjund statute and the NCP. Details not provided in the Proposed
Plan may be gleaned from the Administrative Record file compiled for the Site. Neither
the Proposed Plan nor the Record of Decision are intended to contain the level of detail
necessary to actually implement the selected remedy, this information is developed
during the Remedial Design Phase of the cleanup. The level of detail developed for each
of the alternatives (and reported in the Proposed Plan and Record of Decision) is,
however, sufficient to enable the Agency to apply the nine decision criteria established in
the NCP in the selection process.
3. Which "nearby residents" have home well treatment systems, and how can those who do
not have a home well treatment system obtain one?
EPA Response: During the Remedial Investigation EPA sampled residential wells in the
vicinity of the Site that had the potential of being impacted by the Site contamination.
Upon review of the results, in 1997 EPA provided filters to those residences which may
have been impacted from the Site. EPA does not have any evidence indicating that there
currently are additional homes with wells impacted by the Site. There are a number of
commercially available treatment systems for individual purchase for those who are
concerned about the quality of their well water.
ft. Comments of Debi Station
In an electronic mail message dated March 3, 1998, Debi Slatkin, a resident of Upper
Black Eddy, submitted comments to EPA regarding the preferred alternative for the
Boarhead Farms Superfund Site.
1. Once the remedy is hi place the Site should be used as a public nature preserve or similar
use. The land should not be taken out of use and therefore should not be capped
(Alternative 3) nor an onsite landfill created (Alternative 5).
EPA Response: EPA does not intend to cap or construct an onsite landfill. At present the
Site is privately owned, and the owners can use the property as they see fit. Use of the
property does have to be in accordance with existing deed and zoning restrictions and
14
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cannot interfere with the ongoing Site remediation. The selected remedy does include
institutional controls which will restrict certain activities in certain areas of the Site in
order to protect the integrity of the remedy.
2. The toxic metals present in the soils should be addressed directly, before they have
leached into the groundwater. These soils will pose a risk to human health and the
environment unless the metals are directly removed from the soil.
EPA Response: While EPA agrees that the best way to deal with metals contamination is
some sort of direct intervention, such an approach is not possible at this Site. The metals
contaminants were disposed of in separate areas at different times, and it is not
technically or economically feasible to excavate and treat each separate area of metals
contamination in the soils. Treatment of different metals requires separate processes,
and the presence of other contaminants could significantly inhibit the removal process
and would elevate costs considerably. The diabase rock formation on which most of the
Site is located prevents most of the metals from leaching into the groundwater aquifer
used by the area residences for drinking water. EPA will treat and remove the hazardous
metals present in the surficial aquifer and in the surface soils by the addition of a metals
precipitation unit in the current groundwater collection and treatment system.
3. Additional extraction wells should be placed downgradient from all hot spot areas. In
addition, more residential well testing should take place.
EPA Response: EPA will consider the placement of additional wells based on the results
of the monitoring to determine the effectiveness of the existing groundwater collection
trench. EPA is concerned that additional extraction wells may either dewater the
wetland areas, or if of sufficient depth, pull down the water table and leave residences
without drinking water. Monitoring wells were placed downgradient from the areas
and are monitored on a regular basis. Once the hot spot areas are remediated, the high
levels of benzene and TCE in the soils will be removed and will not appreciably leach
into the groundwater. In addition, the TCE hot spot is located in a wetland area and
EPA believes that the TCE in the groundwater is being remediated through natural
remediation within the existing 'wetland plants. This is evidenced by the lack of TCE in
the downgradient monitoring wells located along Lonely Cottage Road.
EPA has sampled residential wells in the past. Such monitoring will continue as part of
the selected remedy until the determination is made that no jurther residential well
monitoring is necessary.
15
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C.
3.
Comments of the Bridgeton Township Planning Commission
^^^^^^^^I^^^:^T
contamination in our township after EPA leaves the Site. 8 *
EPA Response: EPA believes that Alternative 6 does protect human health and the
JhJr°^entx dlSCUSSed in both the Proposed Plan and the Feasibility Study
EPA Response: See Response B.2 of Part II of this Responsiveness Summary After the
drum removal actions of 1992 and 1993, a layer of clean fill was placed the
excavation areas and eliminated the exposure risk to surface «/»// &,<*»„*,,..„/ -_ /
will be imnlo d t • *"">•" * > »•»«. iu &urjuce son. institutional controls
pie™entea to restrict excavation and other activities that might adversely
impact the effectiveness of this cover. y
Under the description for Alternative 6 it seems that soils that contain heavy metals will
rarTclLTATed ^^ *** ^^ ^ f°f VOCs" We do "« ** * *
area capped (Alternative 3) or an onsite landfill created (Alternative 5). Treatments
°r Phyt°remediation « *~. — i- concentrations in soils
EPA Response: EPA mil place clean fill in the excavated hot spot areas. EPA does not
££3J * T° T ''fT™ ^ 0nSit£ landfil1 EPA >"* ™* Wed ™rfactant
flushing and beheves that the Site is too large for surfactant flushing to be of benefit. In
addition, swfactant flushing is most beneficial in groundwater with high levels of non-
aqueous phase liquids (NAPLs), which do not pose a problem at the Boarhead Farms
Site (see the memo from Jim Harper, Site RPM to File: " Boarhead Soils Remediation"
(undated) included in the Administrative Record for the Boarhead Farms Site) EPA
beheves that the onsite wetlands are currently performing natural remediation in the
1CL hot spot area Inaddition, the selected remedial action includes treatability studies
to determine if phytoremediation will aid in uptake of contaminants from the main
disposal area.
16
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4. We would also like to see extraction wells in, or downgradient from, all the identified hot
spots. We wish to keep the wetlands as protected as possible - extraction wells, rather
than an additional trench, will have much less of an environmental impact.
EPA Response: See Response B.3 of Part II of the Responsiveness Summary regarding
the additional extraction wells. EPA does not plan to install an additional interception
trench along the perimeter of the wetlands since such installation would destroy a
natural habitat that is performing natural remediation.
5. EPA should continue to test and monitor residential wells for toxicity to assure that
contamination is not spreading. We request that EPA provide the Township with updated
maps showing the residential and monitoring well contamination at each test interval.
EPA Response: Testing of residential wells will continue as part of the selected remedy
until EPA determines that such testing is no longer necessary. EPA has provided the
Township with the Remedial Investigation Report which contains extensive maps
delineating the areas of contamination. As progress towards the Site remediation
continues, EPA will provide the community with additional findings and information,
D. Comments of Jonathan C. Roller!
In a one-page letter dated March 10,1998, Jonathon C. Rolled, a resident of Upper Black
Eddy, submitted comments to EPA regarding the alternatives listed in the Proposed Plan
for the Boarhead Farms Site.
1. Alternative 6 does not protect the citizens surrounding the Site, nor does it solve the long
term goals EPA should have foremost in its mind.
EPA Response: See Response C.I in Part II of this Responsiveness Summary.
2. The contamination in the soils should be addressed directly through processes such as
surfactant flushing or phytoremediation.
EPA Response: See Response C.3 in Part II of this Responsiveness Summary.
3, The idea of an onsite landfill (Alternative 3) is not hi the best interests of anyone, and
does not show that EPA has thoroughly examined the effects such an idea would have on
the surroundings.
EPA Response: EPA does not intend to construct an onsite landfill as part of the
remedial action. However, onsite landfills have been used at other Super/und sites and
can be, under appropriate circumstances, an acceptable component of the remedial
17
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action. The Feasibility Study in the Administrative Record describes EPA's reasoning
for consideration of the onsite landfill as well as a comparison with other options.
E. Comments of the Upper Black Eddy Historic Preservation Society (UBEHPS)
In a two-page letter dated March 25,1998 Roger W. Keller, AIA and President of the
UBEHPS, submitted comments to EPA regarding EPA's Boarhead Farms Proposed Plan.
1. The plan does not include removal of all soil containing toxic metals as well as the
specific source of these contaminants. Even after the metals precipitation process is
implemented, the metals in the surface soil will continue to pose a risk to the community.
We do not wish to see the area capped, or an onsite landfill created and want the EPA to
return the Site to a pristine condition by removing all contaminated soils.
EPA Response: See Responses B.2, C.3, andD.3 in Part HI of this Responsiveness
Summary.
2. We are gravely concerned at the suggestion of containment of toxic materials hi our
sojls and water - both our drinking supply and the water that is fed into streams, the
Delaware Canal, and Delaware River. Bridgeton Township relies solely on groundwater
as a potable water supply, no amount of remaining toxicity is acceptable. We must be
assured that the Site is clean both now and well into the future if such containment plans
prove inadequate or the monitoring has ended.
EPA Response: EPA has determined that the selected remedy is protective in that all
unacceptable risks will be eliminated and believes that Alternative 6presents the best
balance of the nine criteria set forth in the NCP. Removal of all hazardous substances is
neither necessary nor cost-effective. As part of this remedy, selected home -wells and Site
monitoring wells will continue to be monitored to ensure that the selected remedy meets
the Performance Standards.
3. The EPA must continue to test and monitor residential wells hi Bridgeton Township for
toxicity. We trust that EPA will do this for properties hi areas adjacent to the Site and the
22 contaminated wells; we want to see testing of outlying areas for assurance over time
that the toxicity is not spreading.
EPA Response? See Response C.5 in Part HI of this Responsiveness Summary. In
addition, outlying monitoring wells will continue to be sampled as part of the selected
remedy to ensure that contamination is not migrating qffsite.
4. We request that EPA provide Bridgeton Township with an updated map showing
residential and monitoring well contamination at each test interval. We would also like
to see maps that plot the interpolated concentration and spread of contaminants.
18
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EPA Response: See Response C.5 in Part III of this Responsiveness Summary.
F. Comments of Wegard D. Holby
In a one-page letter dated March 25,1998 Wegard D. Holby, a resident of Upper Black
Eddy, submitted comments on the alternatives presented in the Boarhead Farms Proposed
Plan.
1. The proposed plan to "remediate" the Boarhead Farms Site in Bridgeton Township by
simply capping the area or creating an onsite landfill is a concern. In a growing
residential community that relies exclusively on well water the plan seems shortsighted
and may pose significant risks to our community.
EPA Response: While capping (Alternative 3) is often implemented by EPA at sites with
multiple component contaminants, such as those present at this Site, our evaluation using
the decisionmaking criteria set forth in the NCP indicates that there are more effective
methods for addressing the contaminants present. Therefore, EPA did not select capping
(Alternative 3) nor an onsite landfill (Alternative 5) as the preferred alternative for
remediation. In addition, EPA is currently treating the groundwater through the onsite
treatment plant and through carbon filtration on residential -well systems. The selected
alternative will provide further groundwater remediation to reduce risks presented by the
Site to the residential water supply.
G. Comments of Larry Schultz
In a two-page letter dated April 2,1998 Larry Schultz, a resident of Upper Black Eddy,
submitted comments to EPA regarding EPA's Boarhead Farms Proposed Plan.
1. EPA should be sure to remediate on the side of health and well being of the surrounding
residents rather than concentrating on cost effectiveness.
EPA Response: EPA selects a remedy using the nine criteria set forth in the NCP, 40
C.F.R. Section 300.430(e)(9). These criteria are biased toward the overall protection of
human health and the environment. The data collected and remedy selected are carefully
reviewed by EPA toxicologists and other Agencies (such as the Agency for Toxic
Substances and Disease Registry) that specifically deal with community health issues.
While the NCP directs EPA to consider cost among the five primary balancing criteria in
the remedy selection process, the NCP is clear that a remedy must meet the threshold
criteria of overall protection of human health and the environment and compliance with
ARARs. For more information, see the "Comparative Evaluation of Alternatives "
section of the Boarhead Farms Proposed Plan or the section of the same title in this
Record of Decision.
19
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H. Comments of Bridgeton Township Supervisors
In an eight-page letter dated April 3,1998, Barbara H. Guth, Wayne A. Brown, and John
F. Hoemle of the Bridgeton Township Supervisors submitted comments to EPA
regarding the Boarhead Farms Proposed Plan.
1. Offsite migration of hazardous chemicals through the southeastern wooded wetlands and
swamp is not significantly addressed in the preferred remedy.
EPA Response: With the installation of the interceptor trench, contaminants are removed
from the groundwater before they reach the southeastern wooded wetland areas. In
addition, EPA believes that the wetland areas are performing natural remediation on the
contaminants that were present previous to the installation of the trench. At the
suggestion of the community EPA has agreed to include in the selected remedy the
installation of additional monitoring wells in order to be sure that the community
remains protected.
2. The possibility of contamination migrating to the northeast of the Site is not addressed in
the preferred alternative.
EPA Response: The northeastern part of the Site consists of high quality wooded
wetlands. Wetlands serve as natural remediation for VOCs and may also aid in
containing a contaminant plume. A set of monitoring wells lies on the edge of the Site,
between the wetlands and Lonely Cottage Road and would indicate if the contamination
was moving in the northeastern direction. EPA has not found evidence to suggest that
the TCEfrom the hot spot in the wetlands has migrated offsite. There is some analytical
data which indicate that chromium and other metals are present in some nearby
residential wells; however, additional data, including the analytical results from the
monitoring wells located between these residences and the Site contamination, suggest
that these metals concentrations are not Site-related,
3. The possibility that contaminants have migrated into the underground aquifer (used for
residential water supply) from other contaminated wells and areas was not addressed in
the Proposed Plan.
EPA Response: During the Remedial Investigation (a copy of which is contained in the
Administrative Record), EPA performed an extensive study of the groundwater in the
area surrounding the Boarhead Farms Site. The purpose of this study was twofold: I) to
determine the types and concentrations of hazardous substances present in the
groundwater and 2) to identify all potential sources (including, but not limited to, the
Boarhead Farms property) of contaminants which may be contributing to the conditions
present in this area. As part of this study, EPA examined the results from both the
residential wells as well as the data obtained from the monitoring wells installed by EPA.
20
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As is common with many hazardous waste sites, EPA found contamination unrelated to
the Boarhead Farms Site. In developing this remedy, EPA has determined that there are
currently no other sources in the area which pose an environmental risk to this
community. EPA is satisfied that all risks posed by this Site have been adequately
evaluated in the studies included in the Administrative Record.
I. Comments of Lawler, Matusky & Sketty Engineers, LLP (LMS) on behalf of the
Boarhead Farms PRP Group
In a 25 page document dated April 3, 1998, LMS, on behalf of the Boarhead Farms PRP
Group, submitted comments on the Proposed Plan for the Boarhead Farms Site.
1. The proposed addition of metals removal is not warranted by Site conditions. The
treatment system already meets PADEP 1197 guidance for discharge swales. We
recommend that EPA work directly with PADEP to develop precise effluent limits that
protect the water quality criteria of receiving waters. The use of ion exchange units at the
wells where the inorganics of concern are being found at elevated levels would more
efficiently assure the reduction of metals in the discharge.
EPA Response: Analyses of the groundwater collected by the existing collection trench
indicates that there are elevated levels of metals which currently exceed maximum
concentration limits (MCLs). EPA has not yet provided PADEP with all requisite
information to determine NPDES limits and alternate values may be developed as a
result of this design effort; however, based on the ecological studies performed by EPA
and contained in the Administrative Record, the current discharge-from the groundwater
collection trench will require treatment for metals prior to discharge.
2. Air emissions from the air stripper easily meet the PADEP air emission requirements and
therefore do not require the addition of off-gas carbon treatment for VOCs.
EPA Response: Since a full study of the air emissions from this unit has not yet been
performed, EPA believes the addition of a vapor-phase carbon unit for off-gas treatment
is necessary. Some initial crude measurements, using OVAs, indicate that vapor control
measures will be required Furthermore, under 25 Pa. Code Section 121.1, all of Bucks
County, including the Site, is located within the Southeast Pennsylvania Air Basin, which
is considered a non-attainment area for ozone. These high ozone levels require that
organic vapor emissions be limited.
3. The October 1997 Soil Aeration Analysis performed by EPA's technical support section
indicates that VOC emissions will not exceed PADEP ah- emission criteria. Carbon
treatment (with an approximate cost of $1 million) therefore is far more than is necessary
to protect human health and the environment from air emissions.
21
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EPA Response: It is premature to argue the merits of various forms of requisite emissions
controls and limitations. The selected remedy requires that emissions from remedial
actions comply with all federal and state ARARs. During the remedial design phase of
the remedy this issue can be addressed and modifications made to the remedial action, if
and as appropriate.
4. With respect to offsite residential wells, the PADOH, in conjunction with the Agency
for Toxic Substances and Disease Registry (ATSDR), concluded that there is no health
hazard and found that ample protection is provided by natural geologic features and the
remedial work that has already taken place. In light of the fact that 25 years have passed
since the Boarhead Farms Site first received government scrutiny, these conclusions lead
us to believe that carbon filters or ion exchange units on offsite residential wells are not
needed. The traces of contamination that have been found in these wells have not been
linked to the Site.
EPA Response: Both EPA and the PADOH have determined that groundwater flow from
the Site flows directly towards the residences on the eastern side of the property. It is
true that contaminant levels have been low in the monitoring wells located between.the
residences and the Site contamination, but both Agencies are concerned that these
residences remain protected. It is possible that the release of Site-related contaminants
into the aquifer could occur. EPA has determined that the filter systems are necessary to
reduce risks presented by such releases. EPA also agrees that some of the offsite
contamination (e.g., chromium) are most likely not Site-related and are due to the natural
background levels in the underlying diabase bedrock. EPA has taken this into account in
the selected remedy, which does not call for specific action to address such sources.
5. In light of the abundant data that has been collected in the last 25 years, the three
proposed additional sentinel/monitoring wells are not needed to monitor the extent of
natural attenuation. Data in the Administrative Record demonstrate that no unacceptable
risk exists from exposure to surface soil; fencing is necessary only to protect treatment
systems and is not required Site-wide. Instead, a deed restriction barring future
residential use would better protect human health by preventing exposure to probable
subsurface contamination through construction or excavation.
EPA Response: The purpose of the sentinel/monitoring wells is more than just monitoring
the extent of natural attenuation. The wells are needed to ensure continual protection
and that the contamination is not moving toward the residences. The exact number of
sentinel wells is still subject to design considerations and may decrease or increase
based on field determinations. At a minimum, an additional sentinel well is needed at
Lonely Cottage Road where the small stream crosses the road near the Bridgeton
Sportmans Club. Institutional controls to protect the remedy components and the
previously installed soil cover are part of the selected remedy.
22
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6. There is concern that EPA has significantly underestimated the costs of the remedial
alternative in the Proposed Plan. Although the Plan recommends a practical and efficient
"hot spot" removal of contaminated soil, the proposal neither quantifies the number of
areas to be excavated nor clearly identifies criteria to define the extent of the excavations.
EPA Response: EPA has reasonably quantified the hot spots based on extensive sampling
of these areas. EPA has estimated the amount of soil to be excavated from the hot spots
to be approximately 12,000 cubic yards (cy). However, since three removal actions have
occurred and the groundwater treatment system has been in operation since October,
1997, it is likely that the levels of contamination in the hot spot areas have reduced
through both EPA actions and natural remediation through the wetlands. Further
delineation of the extent of the hot spot removal of contaminated soil will take place
during the course of the remedial design. In addition, EPA believes that the associated
costs developed for these remedial alternatives are sound and are not underestimated.
23
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