F.PA/ROD/R03-95/196 copy 2
July 1995
EPA Superfund
Record of Decision
II & II, Inc., Burn Pit
Hanover County, VA
6/30/95
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HH BURN PIT SUPERFUND SITE
HANOVER COUNTY, VIRGINIA
RECORD OF DECISION
PREPARED BY
THE U.S. ENVIRONMENTAL PROTECTION AGENCY
JUNE 1995
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RECORD OF DECISION
HH BURN PIT SUPERFUND SITE
PART I - DECLARATION
I. SITE NAME AND LOCATION
HH Burn Pit Superfund Site1
Hanover County, Virginia
II. STATEMENT OF BASIS AND PURPOSE
This Record of Decision (ROD) presents the final remedial
action selected for the HH Burn Pit Superfund Site, located in
Hanover County, Virginia (Site). This remedial action was chosen
in accordance with the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980, as amended (CERCLA), 42
U.S.C. §§ 9601 et seq.. and the National Oil and Hazardous
Substances Pollution Contingency Plan (NCP), 40 C.F.R. Part 300.
This decision document explains the factual and legal basis for
selecting the remedial action and is based on the Administrative
Record for this Site. An index of documents included in the
Administrative Record may be found at Appendix A of' the ROD.
The Virginia Department of Environmental Quality (VDEQ) has
commented on the selected remedy and the State's comments have
been incorporated to the extent possible.
III. 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, as
discussed in Section VI (Summary of Site Risks) of this ROD, if
not addressed by implementing the remedial action selected in
this ROD, may present an imminent and substantial endangerment to
public health, welfare, or the environment.
IV. DESCRIPTION OF THE SELECTED REMEDY
The Environmental Protection Agency (EPA), in consultation
with VDEQ, has selected the following remedial action for the HH
Burn Pit Superfund Site. This remedy addresses contaminated
soil, sediment, surface water, and ground water at the Site. The
selected' remedy is comprised of the following major components:
1 The Site has been identified using different names in
many of the documents in the Administrative Record and on the
National Priorities List. This Record of Decision will refer to
the Site as the "HH Burn Pit Superfund Site."
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• Excavation of contaminated soil in the unsaturated zone
above the water table (i.e., above the depth of four to
six feet) where soil cleanup levels in Table 12 of the
ROD are exceeded;
• Excavation of contaminated sediments from the drainage
ways downgradient of the bermed disposal area where
contaminant concentrations exceed the sediment cleanup
levels listed in Table 12 of the ROD;
• Disposal of contaminated soils and sediments that do
not exhibit hazardous characteristics in a landfill
permitted in accordance with the Resource Conservation
and Recovery Act (RCRA) Subtitle D requirements;
• Treatment and disposal of contaminated soils and
sediments that exhibit hazardous characteristics at a
RCRA-permitted Subtitle C facility;
• Disposal of soils found to contain polychlorinated
biphenyls (PCBs) above 50 mg/kg at a Toxic Substances
Control Act (TSCA) landfill;
• Extraction of contaminated ground water containing
Site-related contaminants above the ground water
cleanup levels listed in Table-12 of the ROD;
• Treatment of contaminated ground water by precipitation
and sedimentation to remove metals and by Ultra Violet
(UV) oxidation to destroy organics;
• At the option of responsible parties who may implement
this remedial action, and only if treatability studies
performed during remedial design demonstrate to EPA
that the technologies are effective, air sparging and
soil vapor extraction may be implemented to accelerate
the removal of contamination from saturated soils and
ground water.
• Implementation of a monitoring program to verify
performance of the ground water treatment system and
detect any impacts to the tributary, surrounding
wetlands, and the nearest residences downgradient of
the Site.
V. STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the
environment, complies with Federal and State requirements that
are legally applicable or relevant and appropriate to the
remedial action, and is cost-effective. The remedy utilizes
permanent solutions and alternative treatment technologies to the
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maximum extent practicable, and, in the case of ground water,
satisfies the statutory preference for remedies that employ
treatment that reduces toxicity, mobility, or volume as a
principal element.
Because this remedy will result in hazardous substances
remaining onsite above health-based levels, a review will be
conducted within five years after initiation of the remedial
action to ensure that the remedy continues to provide adequate
protection of human health and the environment.
s^ /
Thomas C. Voltaggio / / / Date
Director v y .//
Hazardous Waste Management Division
Region III
Environmental Protection Agency
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TABLE OF CONTENTS
PART'I - DECLARATION
I . SITE NAME AND LOCATION 1
II . STATEMENT OF BASIS AND PURPOSE 1
III . ASSESSMENT OF THE SITE 1
IV. DESCRIPTION OF THE SELECTED REMEDY 1
V-. STATUTORY DETERMINATIONS ' 2
PART II - DECISION SUMMARY
I . SITE NAME, LOCATION, AND DESCRIPTION : . 4
II . SITE HISTORY AND ENFORCEMENT ACTIVITIES 7
III . HIGHLIGHTS OF COMMUNITY PARTICIPATION 9
IV. SCOPE AND ROLE OF THE RESPONSE ACTION 10
V. SUMMARY OF SITE CHARACTERISTICS 10
A. General 10
B. Surface Hydrology 11
C. Geology 11
D. Hydrogeology 11
E. Wetlands 13
F. Extent of Contamination 15
1. Surface Soil : 15
2 . .Subsurface Soil • 15
3 . Ground Water 24
4. Surface Water 30
5. Sediments 30
6. Air 35
VI . SUMMARY OF SITE RISKS 35
A. Data Collection and Evaluation 35
B. Exposure Assessment 36
C- Toxicity Assessment 39
D. Health Effect Summary 44
E. Risk Characterization 49
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VII . SUMMARY OF SITS ECOLOGICAL RISKS 50
A. Selection of Contaminants of Ecological Concern ...54
3. Exposure Assessment 55
1. Organic Exposure Point Concentrations 56
2. Metals Exposure Point Concentrations 57
C. Summary of Risks and Uncertainties 57
VIII . DESCRIPTION OF ALTERNATIVES ; 59
IX. COMPARISON OF ALTERNATIVES . 69
A. Overall Protection of Human Health and the
Environment 71
B. Compliance with Applicable or Relevant and
Appropriate Requirements '. 72
1. Chemical-Specific ARARs 72
. 2. Action-Specific ARARs 72
3. Location-Specific ARARs 76
C. Long-Term Effectiveness 76
D. Reduction of Toxicity, Mobility, or Volume
Through Treatment 76
E. Short-Term Effectiveness 77.
F. Implementability 77
G. Cost Effectiveness 78
H. State Acceptance , 79
I. Community'Acceptance 79
X. SELECTED REMEDY AND PERFORMANCE STANDARDS 79
A. Soil and Sediment Excavation Performance
Standards 79
3. Soil/Sediment Treatment and Disposal Performance
Standards 82
C. Ground Water Treatment System Performance
Standards . . 82
XI. STATUTORY DETERMINATIONS 84
A. Overall Protection of Human Health and the
Environment 84
3. Compliance with Applicable or Relevant and
Appropriate Requirements "..... 84
C. Cost Effectiveness ^ 85
D. Utilization of Permanent Solutions and Alternative
Treatment Technologies to the Maximum Extent
Possible 85
E. Preference for Treatment as a Principal Element .. 86
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X.
DOCUMENTATION OF SIGNIFICANT CHANGES ................ 35
A. Soils Excavation ................................ 35
3 . Cleanup Levels .................................. 35
C. Air Sparging and Soil Vapor Extraction ......... . 37
D. RCRA Listed Hazardous Waste Issues ............ . . 33
PART III - RESPONSIVENESS SUMMARY
I. ORAL COMMENTS FROM JANUARY 11, 1994 PUBLIC MEETING .... 90
II. WRITTEN COMMENTS RECEIVED DURING THE FIRST PUBLIC
COMMENT PERIOD .......................... . ............. 95
III. COMMENTS RECEIVED DURING THE COMMENT PERIOD FOR THE
REVISED PROPOSED REMEDIAL ACTION PLAN ................. 118
LIST OF TABLES
Table 1 - • Maximum Detected VOCs in Subsurface Soil ....... 19
Table 2 '- Maximum Detected Semi-Volatiles in Subsurface
Soil ........................................... ~ 20
Table 3 - Total Organic Concentrations Detected in
Subsurface Soil ........................ . ....... 21
Table 4 - Total Inorganic Concentrations Detected in
Subsurface Soil .............. _ .................. 25
Table 5 - Reasonable Maximum Exposure Point
Concentrations ................................. 37
Table 6 - Reasonable Maximum Exposure Assessment Factors . 40
Table 7_ - Slope Factors and Reference Doses .............. 42
Table 8 - Reasonable Maximum Cancer Risks ................ 51
Table 9 - Reasonable Maximum Hazard Indices .............. 53
Table 10 - Applicable or Relevant and Appropriate
Requirements (ARARs) . . ......................... 74
Table 11 - Cost of Remedial Alternatives .................. 73
Table 12 - Performance Standard Cleanuo Levels ............ 80
111
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LIST OF FIGURES
Figure 1 - Site Location Map 5
Figure 2 - Site Disposal Area 5
Figure 3 - Stream Location Map 12
Figure 4 - Vegetative Cover Map 14
Figure 5 - Organic Concentrations in Surface Soil 16
Figure. 6 - Inorganic Concentrations in Surface Soil 17
Figure 7 - Soil Boring Locations 13
Figure 8 - ' Organic Contaminants in Groundwater '. 27
Figure 9 - Total VOC Groundwater Plume 28
Figure 10 - Inorganic .Contaminants in Groundwater 29
Figure 11 - Organic Contaminants in Surface Water 31
Figure 12 - Inorganic Contaminants in Surface Water '.. 32
Figure 13 - Organic Contaminants in Sediment 33
Figure 14 - Inorganic Contaminants in Sediment 34
Appendix A
Appendix B
Aooendix C
APPENDICES
Administrative Record Index
Ground Water Cleanup Level Risk Calculations.
'Glossary of Superfund Terms
IV
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RECORD OF DECISION
HH BURN PIT SUPERFUND SITE
PART I - DECLARATION
I. SITE NAME AND LOCATION
HH Burn Pit Superfund Site1
Hanover County, Virginia
II. STATEMENT OF BASIS AND PURPOSE
This Record of Decision (ROD) presents the final remedial
action selected for the HH Burn Pit Superfur.d Site, located in
Hanover County, Virginia (Site). This remedial action was chosen
in accordance with the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980, as amended (CERCLA), 42
U.S.C. §§ 9601 et seq., and the National Oil.and Hazardous
Substances Pollution Contingency Plan (NCP), 40 C.F.R. Part 300.
This decision document explains the factual and legal basis for
selecting the remedial action and is based on the Administrative
Record for this Site. An index of documents included in the
Administrative Record may be found at Appendix A of the ROD. •
The Virginia Department of Environmental Quality (VDEQ) has..
commented on the'selected remedy and the State's comments have
been incorporated to the extent possible.
III. 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, as
discussed in Section VI (Summary of Site Risks) of this ROD, if
not addressed by implementing the remedial action selected in
this ROD, may present an imminent and substantial endangerment to
public health, welfare, or the environment.
IV. DESCRIPTION OF THE SELECTED REMEDY
The- Environmental Protection Agency (EPA), in consultation
with VDEQ, has selected the following remedial action for the HH
Burn Pit Superfund Site. This remedy addresses contaminated
soil, sediment, surface water, and ground water at the Site. The
selected remedy is comprised of the following major components:
1 The Site has been identified using different names in
many of the documents in the Administrative Record and on the
National Priorities List. This Record of Decision will refer to
the Site as the "HH Burn Pit Superfund Site."
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• Excavation of contaminated soil in tne unsaturated zone
above the water table (i.e., above the depth of four to
six feet) where soil cleanup levels in Table 12 of the '
ROD are exceeded;
• Excavation of contaminated sediments from the drainage
ways downgradient of the bermed disposal area where
contaminant concentrations exceed the sediment cleanup
levels listed in Table 12 of the ROD;
• Disposal of contaminated soils and sediments that do
not exhibit hazardous characteristics in a landfill
permitted in accordance with the Resource Conservation
and Recovery Act (RCRA) Subtitle D requirements;
• Treatment and disposal of contaminated soils and
sediments that exhibit hazardous characteristics at a
RCRA-permitted Subtitle C facility;
• Disposal of soils found to contain polychlorinated
biphenyls (PCBs) above 50 mg/kg at a Toxic Substances
Control Act (TSCA) landfill;
• Extraction of contaminated ground water containing
Site-related contaminants above the ground water
cleanup levels listed in Table 12 of the ROD;
• Treatment of contaminated ground water by precipitation
and sedimentation to remove metals and by Ultra Violet
(UV) oxidation to destroy organics;
• At the option of responsible parties who may implement
this remedial action, and only if treatability studies
performed during remedial design demonstrate to EPA
that the technologies are effective, air sparging and
soil vapor extraction may be implemented to accelerate
the removal of contamination from saturated soils and
ground water.
• • Implementation of a monitoring program to verify
performance of the ground water treatment system and
detect any impacts to the tributary, surrounding
wetlands, and the nearest residences downgradient of
the Site.
V. STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the
environment, complies with Federal and State requirements that
are legally applicable or relevant and appropriate to the
remedial action, and is cost-effective. The remedy utilizes
permanent solutions and alternative treatment technologies to the
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maximum extent practicable, and, in che case of ground water,
•satisfies the statutory preference -for remedies chat employ
treatment that reduces toxicity, mobility, or volume as a
principal element. •
Because this remedy will result in hazardous substances
remaining onsite above health-based levels, a review will be
conducted within'five years after initiation of the remedial
action to ensure that the remedy continues to provide adequate
protection of human health and the environment.
Thomas C. Voltaggio Date
Director
Hazardous Waste Management Division
Region III
Environmental Protection Agency
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RECORD OF DECISION
HH BURN PIT SUPERFUND SITE
PART II - DECISION SUMMARY
I. SITE NAME, LOCATION, AND DESCRIPTION
The .HH Burn Pit Sice is located in Kanover County, Virginia,
approximately 12 miles northwest of the City of Richmond on
Staples Mill Road (Route 33) and 0.5 mile south of the small
community of Farrington, Virginia (See Figure 1).
The Site is defined as all areas found presently, or in the
future, that are impacted by contamination-that resulted from
hazardous waste disposal operations previously conducted at this
location. The Site currently includes: 1) contaminated soil in a
circular clearing approximately one acre in size, hereafter
referred to as "the disposal area"; 2) areas of contaminated soil
beyond the disposal area; 3) contaminated portions of an unnamed
intermittent stream that originates in the disposal area and
flows westward approximately 2,800 feet to the Black Haw Branch;
and 3) the area of the contaminated ground water plume.
The Site is located on a 73.5-acre parcel of land currently
owned by T. Frank Flippo and Sons, a Virginia limited partnership
formed on July 15, 1985.
Solvent's from printing press cleaning operations, printing
ink residues, and other materials were burned in two pits,
designated'as the "West" and "Northeast" Burn Pits, located in
the disposal area. The disposal area is approximately 260 feet
in diameter and is surrounded by a raised berm of native soil
approximately two to four feet high. The berm was created when
the disposal area was cleared. Presently, a band of trees
extend 20 to 50 feet beyond the disposal area and along the path
of the intermittent stream (See Figure 2).
The rest of the 73.5-acre property was clearcut in 1990 as
part of Mr. Flippo's lumber business, and only low brush and
young trees remain. No structures exist on the property.
Access to the Site is limited to a dirt road, which is
approximately 1,200 feet long and perpendicular to the west side
of Route 33. A locked cable located at the approximate half-way
point of the road restricts vehicular access. No barriers er.ist
that would restrict pedestrian access.
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H & H
INCORPORATED
SITE
RICHMOND
INTERNATIONAL
AIRPORT
SOURCE: Ecology and Env»onm«ra. Inc. 1992
SCALE
2.5
5 Mils*
a
Figure 1
H&H INCORPORATED
SITE LOCATION MAP
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Figure 2 M * H sm
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II. SITE HISTORY AND ENFORCEMENT ACTIVITIES
The Site property was purchased in 1950 by Mr. Howze
Haskell. From approximately 1960 to 1976, the Site was owned and
operated by the Haskell Chemical Company, Inc., which manufac-
tured chemicals at an off-site plant for distribution to several
companies in the Richmond area.
From 1960 to 1976, the Site was used to burn solvents from
printing press cleaning operations, printing ink residues, and
other materials collected by the Haskell Chemical Company and
otherwise brought to the Site for disposal. Much of the waste
was brought in 55-gallon drums and stored on-site in one of two
major collection areas. For disposal, wastes were emptied into
one of two pits and burned. The burn pits are no longer visible
since the disposal area has been graded.
Although operations ceased in 1976, the Site became part of
Mr. Haskell's newly formed holding company, HH Incorporated (HH) ,
in 1977. In June 1981, HH submitted the Notification of
Hazardous Waste Site (Form 8900-1) to the EPA, as required by
CERCLA. The property was conveyed to the present owners, T.
Frank Flippo and Sons, a Virginia limited partnership, in July
1985. •
The Virginia Department of Health, Division of Solid and
Hazardous.Waste (VA DSHW), the agency responsible for hazardous
waste regulation prior to the establishment of the Virginia
Department of Waste Management (VDWM), initially managed
investigation activities at the Site. Six residential wells were
sampled in November and December 1981 to determine if there was
evidence of migrating contamination. The VA DSHW determined that
the level of organic and inorganic contaminants in the
residential wells did not exceed background levels. In December
1981, VA DSHW approved a cleanup plan for the Site prepared by
HH, which, if implemented, would remove the sources of
contamination.
In May 1982, approximately 1,000 empty drums stored in the
two collection areas were reportedly crushed on Site and
transported to a hazardous waste disposal facility under the
supervision of the VA DSHW. Stained soil, including the soil
that lined the burn pit, was also reportedly removed from the
Site at the same time. A soil erosion and sediment control
program was initiated. The plan included grading and stabilizing
soils, interception and containment of run-off, and reseeding and
planting. On August 2, 1982, two monitoring wells, one
upgradient and the other downgradient, were installed at the Site
under the direction of the Virginia State Water Control Board.
Based on the analytical results of water samples taken from these
wells in October 1982, no conclusive evidence of groundwater
contamination was found.
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In response to community concerns, a general health survey
was conducted by the Virginia Department of Health in May 1933'.
Thirty-five households were surveyed, representing 143
individuals. Based on the survey, no conclusive evidence linking
health problems to Site contamination was found.
EPA conducted a non-sampling preliminary assessment of the
Site on March 16, 1983. On March 27, 1984, EPA performed a Site
Inspection (SI) that included sampling of groundwater, sediments,
leachate, and runoff water. Analytical results of these samples
revealed the presence of polychlorinated biphenyls (PCBs),
organics (such as benzene, xylene, toluene, and naphthalene), and
inorganics (beryllium and cobalt) in a downgradient monitoring
well. These results, combined with the knowledge that waste
burning had occurred at the Site, raised concerns that dioxin
might be present at the Site (the burning of PCBs is known to
create dioxin compounds). The SI report was published in October
1985 .
On -December 3, 1985, EPA performed a dioxin screening at the
Site that involved sampling soil and sediment for dioxin within
the bermed disposal area and on the outer perimeter of the
disposal area to the north, southwest, and west. Results of the
analyses showed the'presence of dioxin and dibenzofuran isomers.
On October 9, 1986, EPA performed a more extensive sampling study
that involved the collection of 19 field samples for dioxin.
Results of the dioxin analysis showed trace levels of dioxin in
three of the 19 samples. EPA determined that these levels were
sufficiently low so as not to warrant any further dioxin sampling
at the Site. .
The presence of other contaminants including volatile
organic compounds (VOCs), metals, and PCBs did, however, provide
reason for immediate concern at that time.
The analytical data collected were used to evaluate the
relative hazards posed by the Site using EPA's Hazard Ranking
System (HRS). EPA uses the HRS to calculate a score for
hazardous waste sites based upon the presence of potential and
observed hazards. If the final HRS score exceeds 28.5, the Site
may be placed'on the National Priorities List (NPL), making it
eligible to receive Superfund monies for remedial cleanup.- The
Site scored 33.71 using the HRS, was proposed for inclusion on
NPL in Januajry 1987, and finalized in March 1989.
In 1988, EPA commenced a Remedial Investigation and
Feasibility Study (RI/FS) to ascertain the nature and extent of
contamination at the Site and to evaluate remedial action
alternatives. Initial sampling was performed from November 1988
through March- 1989. The Phase I analytical results showed a
higher level of contamination at the Site than expected, and a
potential for further migration. Contamination beyond the burn
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pits and the areas where drummed waste was handled (i.e., the
disposal area) consisted of VOCs, PCBs, pesticides, and
inorganics (lead, zinc, cadmium, copper, and mercury). Ten
residential drinking water wells were tested; however, no
contamination of drinking water believed to be attributable to
the Site was found. Phase II of the RI/FS began in the spring of
1992 and was completed in June 1992.
III. HIGHLIGHTS OF COMMUNITY PARTICIPATION
The documents which EPA used to develop, evaluate, and
select a remedial alternative for the Site have been maintained
at the Pamunkey Public Library, Ashland Branch (Reference
Section), 102 South Railroad Avenue, Ashland, VA 23005 and at
the EPA Region 3, Philadelphia Office.
The RI/FS and Proposed Plan for the HH Burn Pit Site were
released to the public on December 21, 1993. The notice of
availability for these two documents was published in the Ashland
Herald Progress on December 16, 1993 and in the Richmond Times
Dispatch on December 20, 1993. A reminder notice appeared in the
Ashland Herald Progress on December 30, 1993. A public comment
period was held from December 21, 1993 to January 19, 1994. By
request, the public comment period was extended until February
18, 1994.
In addition, a public meeting was held during the public
comment period on January 11, 1994. At this meeting,
representatives from EPA and VDEQ answered questions about the
Site and the remedial alternatives under consideration.
Approximately 65 people, including residents from the impacted
area, local government officials, and news media persons,
attended the meeting.
The initial Proposed Plan contemplated disposal of
contaminated soils and sediments from the Site at a landfill
regulated under Subtitle D of RCRA. In response to concerns
raised during the comment period, EPA revisited the issue and
proposed that Site wastes be considered "listed hazardous wastes"
under RCRA and that, accordingly, such wastes be disposed of at a
landfill regulated under Subtitle C of RCRA after such wastes
were treated to the extent necessary to meet RCRA Land Ban
Restrictions.
These treatment requirements and disposal restrictions
associated with management of RCRA listed hazardous wastes
significantly increased EPA's cost estimates for several of the
remedial alternatives detailed in the initial Proposed Plan. EPA
accordingly issued a Revised Proposed Remedial Action Plan on
December 22, 1994, and held a public meeting to explain changes
made to the initial Proposed Plan. Notices of the availability
of the Revised Proposed Remedial Action Plan and of the scheduled
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public meeting were published in the Ashland Herald Progress on
December 22, 1994 and December 29, 1994, respectively. A public
comment period on the Revised Proposed Remedial Action Plan was
scheduled to run from December 23, 1994 through January 23, 1995.
Upon request, this second comment period was extended through
February 22, 1995. A notice announcing this extension appeared
in the Ashland Herald Progress on January 26, 1995.
. A response to the comments received during the public
comment periods is included in the Responsiveness Summary found
at Part III of this Record of Decision.
IV. SCOPE AND ROLE OF THE RESPONSE ACTION
The remedial action selected in- this Record of Decision is
intended to remediate contamination in soils, ground water,
sediments, and surface water impacted from the release of
hazardous substances from the Site. EPA does not•contemplate
further remedial action for the Site if the cleanup requirements
announced herein are achieved.
V. SUMMARY OF SITE CHARACTERISTICS
A. General
The HH Burn Pit Site is located in a rural area of Hanover
County. The population of Hanover County, based on the 1990
census, is 63,306 persons. With an area of 473 square miles, the
population density is 134 people per square mile. Approximately
46% of the population is urban, and 54% is rural. In 1981, 89%
of Hanover County was agricultural, forested, or undeveloped.
According to recent traffic zone maps provided to EPA by the
senior county planner, the population density of the area
bordered by U.S. Route 33, State Route 623, and the Chickahominy
River is 55.7 persons per square mile. . Using this figure, EPA
estimates the number of people currently living within a one-mile
radius of the Site to be 175. Since the 1950s, Hanover County's
growth has been largely attributed to urban migration from
Richmond, Virginia. In 1991, Hanover County estimated that
two-thirds of its employed residents commuted to the Richmond,
Virginia area for work.
The land surrounding the Site is primarily woodlands and
farm fields, but an increasing number of residential homes are
being built. Public roads exist within one mile of the Site in
every direction. As of the early 1980s, developed land in
Hanover County included residential (8% of the developed land
within the county), commercial (0.4%), industrial (0.6%), and
public (2%). Most of the urban development has occurred along
the major highways, which include Interstate 95, Interstate 295,
and U.S. Route 1.
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B. Surface Hydrology
The Site and surrounding areas are characterized by a gently-
sloping, relatively flat terrain drained by intermittent streams'.
The bermed disposal area drains into an intermittent stream that
flows westerly to the Black Haw Branch and eventually to the
Chickahominy River (See Figure 3). Precipitation slowly
infiltrates into the saprolite and saprolite-derived soils at the
Site to the depth of the shallow water table. North and east of
the Site, where elevations are the highest, the water table is
four to six feet below the ground surface. West of the Site
along the intermittent stream down to its confluence with the
Black Haw Branch, the water table is less than one foot below the
ground surface. Site contaminants have been transported along
the intermittent stream during rain events. Four logging roads
cross the intermittent stream. The logging road nearest the
bermed area has served to slow the flow of surface water from the
disposal area and has deflected the flow in a north/south
direction along the logging road.
C. Geology
The HH Burn Pit Site lies within the Piedmont Plateau
Physiographic Province approximately five miles west of the fall
line, which distinguishes the Piedmont Plateau from the Atlantic
Coastal Plain. The Piedmont Plateau Province has mature rolling
topography that consists of gently sloping ridges with very steep
slopes along drainage ways. This province's geology is
characterized by a thick mantle of saprolite, which is a clay-'
rich uncbnsolidated material overlying fractured crystalline and
metamorphic bedrock. The surface elevation at the Site ranges
from 290 to 300 feet above mean sea level with the land surface
relatively flat to gently sloping to the west.
The Site is directly underlain by saprolite which is derived
from in-situ weathering of the underlying crystalline bedro'ck,
which at this Site is the Petersburg granite. The overburden,
which is unconsolidated material that overlies bedrock, consists
of soils derived from the saprolite and ranges in thickness from
63 to about 71 feet at the Site. Absent at the Site, but mapped
as occurring in close proximity to it, a 20 foot or less thick
Tertiary age gravel composes the uppermost portion of the
overburden. The grain size of the saprolite ranges from fine to
coarse with a general upward fining sequence. The Upper
Paleozoic age Petersburg granite is the bedrock underlying the
Site.
D. Hydrogeology
The overburden (i.e., saprolite) aquifer is about 50 feet in
saturated thickness at the Site and immediately overlies the
Petersburg bedrock aquifer. While saturated soils were
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>-^>^v\—' /<
LACK HAW BRANCH
J \ A. ; W*^-/l
SOOSCS. uSGS 7.5 MnuM S*ri«s (Topograpnc) QuadrangM: Gitn AlMn. VA. 1963. Pnoox«v
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encountered at two to five feet below the ground surface, ground
water flow into a borehole was encountered at roughly 12 feet
below ground surface. This appears to be a result of the clay-
rich soils which are present to this approximate depth within the
bermed disposal area. The average hydraulic conductivity of the
overburden aquifer was estimated from slug testing results at
0.00068 feet/minute and the estimated gradient of the water table
is approximately 1.4 percent (i.e., 1.4 feet per 100 feet) toward
the west. An average linear velocity was estimated at 20
feet/year using the preceding information and assuming an average
effective porosity of 25 percent. The general ground water flow
direction in the overburden aquifer is toward the west and
appears to mimic surface topography. The overburden aquifer is
recharged through percolation of rain. There are residential
wells that obtain water from the overburden aquifer in the Site
vicinity at reported total depths ranging from 20 to 50 feet.
The bedrock aquifer underlying the Site is the Petersburg
granite aquifer. Ground water occurs within secondary porosity
features, such as fractures, in the Petersburg granite. Four
bedrock monitoring wells were installed during the RI/FS to
evaluate the extent of ground water contamination. . Three of the
bedrock monitoring wells were constructed in the shallow portion
of the Petersburg aquifer and one monitoring well was constructed
in the deeper portion. Ground water movement will depend on the
orientation and interconnection of fractures. While the ground
water flow direction is most likely controlled by fractures, the
general direction for ground water flow in the bedrock aquifer is
to the west-northwest with an estimated gradient of 2.4 percent.
At the Site, the bedrock aquifer is most likely recharged by the
overburden aquifer. The estimated average hydraulic conductivity
for the Petersburg aquifer is about 0.00065 feet/minute.
Residential wells which produce water from the Petersburg aquifer
in the Site vicinity generally have a total depth of 300 feet or
more.
E. Wetlands
Wetlands in the vicinity of the Site are primarily
palustrine systems that have: 1) a dominance of vegetation that
requires high moisture, 2) high moisture soils, and 3) a water
table that inundates the ground surface for some portion of the
growing season. One of the three characteristics maybe absent
in a disturbed system.
Three types of palustrine systems in the vicinity of the
Site are forested, scrub-shrub, and emergent (See Figure 4).
Within the Piedmont province, these wetlands will generally occur
along water courses. The forested wetlands in the area consist
of vegetation similar to the adjacent upland forests. The shrub-
scrub and emergent wetlands in the vicinity of the Site result
primarily from disturbance to forested wetlands. Characteristic
13
-------
I
I
12
I
51
IK
UAlUftl OA» (0«I51
ll'uiu VII All A
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WICO HARDWOOD HtPAAlAH VlllLAHO
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H » H sue
-------
species in che scrub-shrub wetlands include viburnums and
arrowwoods, greenbriers, and blackberries, in addition co che
shrub species typical of the forested wetlands. The emergent
wetlands are dominated by grasses and sedges intermixed with
flowering herbaceous plants.
The wetland habitats are intermixed with upland habitats.
Wildlife usage of this area will tend to be similar to chat in
adjacent upland areas. Wetland, areas tend to be less disturbed
and may provide additional security for breeding animals.
Amphibian populations will be more represented in the wetlands
also.
F. Extent of Contamination
•
The primary objective of the RI was to characterize the
nature and extent of hazardous substances present at the HH Burn
Pit Site. As part of this.effort, the RI identified and .
evaluated potential migration routes for contaminants and
exposure pathways for human and ecological receptors.
1. Surface Soil
All surface soil samples collected in the bermed disposal
area contained relatively high concentrations of PGBs (Aroclor
1248 and Aroclor 1260) and phthalates (See Figure 5). Various
VOCs such as trichloroethene, toluene, and methylene chloride,
were also detected at low levels in surface soil samples
collected in the bermed disposal area. Surface soil samples
collected north (SS-10) and west (SS-9) of the disposal area had
elevated levels of PCBs as well as several other organic
contaminants. ' Surface soil samples collected south of the
disposal area (SS-8, SS-11, and SS-12) were generally free of
organic contamination (low levels of pesticides were detected in
SS-12). - .
Surface soil samples contained elevated levels of six metals
(See Figure 6). Most widespread were lead (Pb) and 'zinc (Zn),
which were detected at maximum concentrations of 835 mg/kg and
3,190 mg/kg, respectively. Antimony (Sb), chromium (Cr), copper
(Cu) , and. selenium (Se) were detected at levels above the upper
90th percentile of the common ranges found in eastern U.S. soils
and, therefore, were considered to be of concern.
2. Subsurface Soil
The locations of the soil borings for Phase I and II of the
investigation are shown on Figure 7. Elevated levels of volatile
and semi-volatile organic compounds were detected wich the
highest concentrations in or near the former burn pit areas.
-------
..."-":.:»-8-":--"-'"-1\
ACIIONI 100 I \
1-euiAHOHi " I \
HI rue HI on CPOHIDC on I \
mo i» | ss «%
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m-H-iumpHiHAiAii i.»oo/)io
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OHI tAUPU COUKIIO r*OM 0-14 cm
f~-/-^,--\ imiuM
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IOIMII (U«N Pll
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SURfACC SOU SAUPUS
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-------
LOCCiO AKtA
MOtl:
• AIL RCSUL1) Aftl tolASURlO IN mo/hi-
• CUIOCUNLS USIO AUC UPPI« null Of «01I> PIICIN1ILI
(IHACHKni AHO iOIKHCLN 1114)
MALI IN liil HO" HOI OIUCIIO AIOVI CUIDiLINIS.
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Figure 6
cAKicri onei u ii AUOVI
UAHU^ IH SUNIACC
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-------
Figure 7 son BODING IOCAIIONS
HAH sue
-------
Maximum concentrations detected, and the locations where these
concentrations were found, are presented in Table 1 for VOCs and
Table 2 for semi-volatiles. Total concentrations of VOC, semi-
volatile, PCB, and pesticide contaminants found in each boring at
various depths are presented in Table 3.
PCBs were detected in subsurface soils at levels ranging up
to 72,000 ug/kg. The highest concentrations were found primarily
in the vicinity of the former burn pits. Significant PCB
concentrations were found primarily in subsurface soil above the
depth of six feet.
A variety of pesticides were found at low levels in all
borings at various depths. Most pesticides detected were found
at depths of less than six feet.
Table 1 - Maximum Detected VOCs in Subsurface Soil
Contaminant
Acetone
1,1-Dichloroethane
Chloroform
1 ,2-Dichloroethane
2-Butanone
Trichloroethene
1 , 1 ,2-Trichloroethane
Benzene
4-Methyl-2-pentanone
Tetrachloroethene
Toluene
Ethylbenzene
Total Xylenes
Maximum
Concentration
(ug/fcg)
9.300J
32
87
1.600J
760.000L
48
26,000
22
34.000J
6.600J
1,600,000
64.000J
540,000
Boring
Number
BH-13
BH-13
BH-13
BH-12
W-5
BH-13
W-6
BH-13
W-5
BH-8
BH-8
BH-8
BH-8
Depth
(feet)
2-4
2-4
2-4
10-12
4-6
2-4
2-4
24
4-6
2-4
2-4
2-4
2-4
Key: J - Data qualifier indicating that analyte is present, but
actual value may be higher or lower
L - Data qualifier indicating that analyte is present, but
actual value may be higher
19
-------
Table 2
Maximum Detected Semi-Volatiles in Subsurface Soil
Contaminant
Phenol
1 ,2-Dichlorobenzene
1,3-Dichlorbenzene
1 ,4-Dichlorobenzene
2-Methylphenol
4-Methylphenol
Isophorone
2,4-Dimethylphenol
Benzoic Acid
Naphthalene
4-Nitrophenol
Phenanthrene
Anthracene
Di-n-butylphthalate
Butylbenzylphthalate
bis(2-ethylbenzyl)phthalate
Di-n-octylphalate
Maximum
Concentration
(ugfrg)
1,600
8.900J
57J
120J
2,400J
3.400J
1,200
4.000J
380J
23,000
100J
4.200J
40J
50.000J
21,000
2.200.000J
5.200J
Boring
Number
BH-8
W-5
BH-8
BH-8
W-6
W-5
BH-9
W-5
NE-1
NE-3
BH-11
W-5
BH-10
NE-1
W-6
BH-7
BH-7
Depth
(feet)
8-10
4-6
4-6
4-6
0-2
4-6
6-8
4-6
4-6
0-2
2-4
4-6
6-8
0-2
0-2
0-2
0-2
Key: J - Data qualifier indicating that analyte is present but
actual value may be higher or lower
L - Data qualifier indicating that analyte is present, but
actual value may be higher
20
-------
Tables
Total Organic Concentrations Detected in Subsurface Soil (ug/kg)
Boring
#
BH-1
BH-2
BH-3
BH-4
BH-5
BH-6
BH-7
BH-8
BH-9
Type
voc
sv
PCS
Pest
VOC
SV
PCS
Pest
VOC
SV
PCS
Pest
VOC
SV
PCS
Pest
VOC
SV
PCS
Pest
VOC
SV
PCS
Pest
VOC
SV
PCS
Pest
VOC
SV
PCS
Pest
VOC
SV
. PCS
Pest
Depth (feet)
0-2
*
*
ND
1
ND
490
30,000
7
*
*
4,400
5
*
*
12
<1
*
*
4,800
3
1
90
9
ND
71,000
£300,000
34,000
25
15,000
35,000
5,600
69
19
72,000
4,800
2
2-4
*
*
ND
ND
ND
48
1,600
0
*
*
7
<1
*
*
140
<1
*
*
15
<1
ND
85
52
<1
ND
100
70
ND
250,000
122,000
5,900
80
350,000
104,000
220
7
4-6
*
*
ND
ND
ND
73
12
0
*
*
ND
ND
*
*
ND
ND
*
*
ND
<1
ND
100
34
ND
ND
110
9
<1
94,000
43,000
7,500
74
21,000
60,000
47
<1
6-8
*
*
ND
ND
ND
72
26
0
*
*
ND
ND
*
*
ND
ND
*
*
ND
<1
ND
68
17
ND
ND
1,800
270
ND
130,00
ND
1,000
86
ND
9,700
9,300
40
. <1
8-10
*
*
*
*
*
*
*
*
*
*
ND
ND
*
*
ND
ND
*
• *
*
*
*
*
*
*
*
*
*
*
300,00
ND
3,000
ND
<1
10-12
*
*
ND
ND
ND
*
120
<1
*
*
*
*
*
*
*
ND
*
*
ND
ND
*
*
*
*
ND
62
ND
ND
12-
14
*
*
*
*
*
*
*
*
*
* -
ND
ND
it
* -
*
*
ND
59
ND
ND
*
*
*
»
14-
16
*
*
*
*
"
*
*
*
*
'
16-
18
*
*
*
*
21
-------
Table3
Total Organic Concentrations Detected in Subsurface Soil (ug/kg)
Boring
#
BH-10
BH-11
BH-12
BH-13
BH-14
BH-15
BH-16
BH-17
BH-18
Type
VOC
SV
PCB
Pest
VOC
SV
PCB
Pest
VOC
SV
PCB
Pest
VOC
SV
PCB
Pest
VOC
SV
PCB
Pest
VOC
SV
PCB
Pest
VOC
SV
PCB
Pest
VOC
SV
PCB
Pest
VOC
SV
PCB
Pest
Depth (feet)
0-2
210
ND
ND
<1
2
5,700
ND
<1
*
*
*
*
*
*
• *
*
*
*
600
2
*
*
ND
<1
*
*
ND
2
*
*
62
1
*
*
80
10
2-4
ND
ND
ND
ND
2
200
ND
ND
ND
240
ND
ND
28,000
20,000
2,100
4
*
*
11
1
*
*
ND
<1
*
*
ND
<1
*
*
0
<1
- •
*
ND
<1
4-6
ND
ND
ND
ND
ND
81
0
<1
ND
60
240
<1
470,000
73,400
13,000
ND
*
*
ND
<1
*
*
ND
>1
*
*
ND
<1
*
*
*
*
*
*
11
<1
6-8
ND
40
25
<1
ND
79
ND
ND
ND
91
ND
ND
ND
120
ND
ND
*
*
7
ND
*
*
ND
ND
*
*
ND
1
*
*
*
*
*
*
ND
ND
8-10
*
*
*
*
* •
*
*
*
1
110
ND
ND
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
10-12
ND
ND
150
ND
*
*
*
*
3.100
ND
ND
ND
1,400
55
ND
<1
»
*
*
*
*
*
340
<1
*
*
*
*
*
*
*
*
12-
14
*
*
*
*
*
*
*
*
*
*
*
*
53
140
29
ND
*
*
ND
<1
it
*
*
*
*
*
*
*
*
*
*
*
14-
16
ND
76
ND
ND
*
*
*
*
*
*
*
*
*
*
*
*
*
*
ND
<1
*
*
ND
<1
16-
18
*
*
*
*
*
*
*
*
*
- *
*
it
22
-------
Tables
Total Organic Concentrations Detected in Subsurface Soil (ug/kg)
Boring
#
NE-1
NE-2
NE-3
W-4
W-5
W-6
MW-2
Type
voc
sv
PCB
Pest
VOC
SV
PCB
Pest
VOC
SV
PCB
Pest
VOC
SV
PCB
Pest
VOC
. SV
PCB
Pest
VOC
SV
PCB
Pest
VOC
SV
PCB
Pest
Depth (feet)
0-2
1,000
863,900
680
47
11
11,100
ND
ND
656,000
221 ,700
1,100
20
6
ND
6,900
ND
1,800
358,900
47,000
ND
75,500
1,168,800
88,000
ND
16
60
530
ND
2-4
25,000
39,000
ND
ND
8
59
ND
ND
130,000
18,000
710
420
ND
ND
430
ND
1,100
302,200
72,000
ND
669,600
69,000
42,200
ND
1,500
ND
ND
ND
4-6
48,000
2,300
ND
ND
26
44
ND
ND
6,300
50
ND
ND
ND
ND
520
ND
1 ,292,000
317,300
27,000
ND
53,100
11,600
3,900
ND
2,900
63
ND
ND
6-8
70,000
39,000
ND
ND
42
ND
ND
ND
8-10
173
ND
ND
ND
10-12
ND
ND
ND
ND
12-
14
14-
16
16-
18
Key:
VOC
SV
PCB
Pest
*
ND
Total Volatile Concentrations
Total Semi-Volatile Concentrations
Total Polychlorinated Biphenyl Concentrations
Total Pesticide Concentrations
No analysis performed
Not detected
23
-------
Subsurface soils were also analyzed for inorganic
contaminants. Since many inorganic elements occur naturally, the
levels found were not considered to be of concern unless they
exceeded the upper limit of the 90th percentile of the common
ranges found in the eastern United States. Table 4 presents the
inorganic data for various depths at each boring where the 90th
percentile values were exceeded. The most prevalent metals found
at elevated levels were copper, lead, and zinc. The highest
concentrations were found generally at depths of less than two
feet and occasionally to the depth of four feet. Beryllium,
selenium, chromium, nickel, and antimony were detected at
elevated levels at random depths and lateral distribution.
3. Groundwater
Organic contaminants detected at elevated levels in
groundwater monitoring wells within the bermed disposal area
include benzene, toluene, vinyl chloride, 1,2-dichloroethane,
tetrachloroethane, 1,1,2-trichloroethane, ethylbenzene, 1,2-
dichloropropane, bis(2-ethylhexyl)phthalate, aldrin, dieldrin,
and heptachlor epoxide (See Figure 8). The approximate location
of the plume of groundwater contamination based on the total
concentrations of VOCs is shown in Figure 9. All overburden
wells (both shallow and deep) within the disposal area contained
organic contamination at levels exceeding the Safe Drinking Water
Act Maximum Contaminant Levels (MCLs). Bis(2-ethylhexyl)
phthalate was the only organic contaminant found at elevated
levels in the bedrock well located in the disposal area.
Monitoring wells located outside the bermed disposal area
were generally free of organic contamination. Monitoring well
MW-4; located immediately downgradient of the disposal area, had
elevated levels of benzene, 1,2-dichloroethane, dieldrin, and
vinyl chloride. Upgradient monitoring well MW-1 showed an
elevated level of toluene during the Phase I sampling; however,
toluene was not detected during the Phase II sampling.
Monitoring wells MW-7 and MW-8 had elevated levels of heptachlor
epoxide and heptachlor, respectively.
Several metals were detected at levels above MCLs in
monitoring wells within or near the disposal area. The metals
appearing most frequently are aluminum, iron, and manganese.
These metals were also found in upgradient monitoring wells and
residential wells at concentrations similar to those detected in
disposal area wells. Figure 10 shows the inorganic contaminants
present at levels of concern in the Site monitoring wells.
Twelve residential wells surrounding the Site were sampled
during the RI. One residential well sample had beryllium at a
concentration slightly above the MCL. Another residential well
sample had a trace concentration of heptachlor epoxide slightly
above the Virginia Groundwater Protection Level, but below the
24
-------
Table 4
Total Inorganic Concentrations Detected in Subsurface Soil (mg/kg)
Boring
#
BH-1
BH-2
BH-3
BH-4
BH-5
BH-6
BH-7
BH-8
BH-9
BH-10
BH-11
BH-1 2
BH-13
BH-14
BH-1 5
Type
Cu
Be
Cu
Pb
Cu
Pb
Zn
Se
Pb
Be
Cu
Pb
Zn
Sb
Be
Cu
Pb
Zn
M
Cu
Pb
" Zn'
Be
Be
Se
Be
Cu
Pb
Zn
Be
Depth (feet)
0-2
**
110
50
36
**
425
398
124
74
2,620
1,100
489
61
276
361
170
82
122
**
*«
*
*
713
528
258
**
2-4
**
11
**
**
**
**
162
137
*»
196
**
**
1
**
**
**
4-6
**
w*
**
**
**
**
**
118
**
**
«»
**
**
*»
**
6-8
*»
**
**
**
1
**
**
**
**
**
**
**
**
**
8-
10
*
*
*
*
*
*
**
*
*
**
*
*
*
10-
12
**
3
**
**
*
**
90
21
3
2
*
*
**
*
*
12-
14
*
*
*
*
2
'
**
*
2
2
**
14-
16
*
*
4
*
*
*
16-
18
*
*
_
25
-------
Table 4
Total Inorganic Concentrations Detected in Subsurface Soil (mg/kg)
Boring
#
BH-16
BH-17
BH-18
NE-1
NE-2
NE-3
W-4
W-5
W-6
MW-2
Type
Cu
Zn
Cu
Pb
Zn
Cu
Pb
Zn
Se
Cu
Pb
Zn
Cr
Se
Pb
Cu
Pb
Zn
Cu
Pb
Zn
Cr
Sb
Depth (feet)
0-2
*'*
664
173
531
37
213
1,190
2,600
285
9
**
2,300
2,020
290
300
<1
112
193
81
9,100
1,390
2,120
364
38
*»
2-4
**
**
**
395
265
166
**
515
463
136
**
85
11,800
1,570
2,270
1,010
199
**
4-6
**
*
**
*»
*«
**
*«
130
71
52
**
6-8
**
*
**
**
*«
8-
10
*
*
**
10-
12
*
*
**
12-
14
*
*
14-
16
**
38
16-
18
*
*
Key:
90th Percentile Value:
Cu Copper ' 49 mg/kg
33 mg/kg
104 mg/kg
2 mg/kg
0.3 mg/kg
112 mg/kg
2 mg/kg
Pb Lead
Zn Zinc
Be Beryllium
Se Selenium
Cr Chromium
Sb Antimony
M Nickel
* No analysis performed
** Not detected
38 mg/kg
26
-------
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Figure 10 INORGANICS otttcito ABOVC STANOAROS
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DURING THE PHASE I AND II Rl
-------
MCL. This residential well is upgradient from the Site. Sample
results from a residential well located over a mile south-
southwest from the Site had a concentration of tetrachloroethene
below the MCL.
4. Surface Water
Organic and inorganic contaminants were detected in surface
water collected from the intermittent stream draining the
disposal area (See Figure 11). PCBs, the primary organic
contaminant, were detected at elevated levels downstream to
sampling location SW-8 approximately 400 feet from the disposal
area.
Inorganics were detected at levels above EPA and/or Virginia
water quality criteria for the protection of aquatic life at all
surface water sampling locations, including those in the Black
Haw Branch (See Figure 12). Inorganics of concern that may be
attributable to the Site are copper, lead, and zinc.
Concentrations of these metals rapidly decrease with distance
from the Site, but exceed background levels for the entire length
of the Site stream. The inorganic contaminants found in sample
locations located along the first logging road downstream from
the disposal area (SW-4, SW-5, and SW-6) indicate that runoff
from the disposal area is diverted along this road.
5. Sediments
Organic contaminants found in sediment samples collected
from the intermittent stream draining the disposal area include
PCBs, pesticides, and phthalates (See Figure 13). In general, no
pesticides or phthalates were detected downstream of the first
logging road crossing, which is approximately 120 feet west of
the disposal area. PCBs, however, were detected at low levels
along the entire length of the Site stream and in the Black Haw
Branch downstream.
Inorganics, including beryllium, copper, chromium, lead, and
zinc, were detected in sediment samples collected from the
intermittent stream (See Figure 14)« Copper and lead were found
at elevated levels most frequently. Elevated levels of inorganic
contaminants were detected downstream to the second logging road
crossing approximately 550 feet west of the disposal area.
Sediment sampling results also indicate that transport of
contaminants by runoff from the disposal area has been diverted
to some extent by the first logging road.
30
-------
i no 7.»
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-------
6. Air
Although no samples of air were collected for analysis and
soil gas sampling was not conducted, some general assumptions can
be made regarding the air transport route based on Site
conditions and results of ambient air monitoring and sample
screening.
When field activities were occurring, the ambient air at the
Site was never observed to be above background levels using an
Organic Vapor Analyzer (OVA) and/or a Photovac Micro-tip photo-
ionization detector (PID). When near-surface soils were
disturbed for sampling purposes, no readings in the breathing
zone were encountered above background levels. When collecting
subsurface soils from split spoon samplers, and during
installation of on-Site borings and monitoring wells, organic
contaminants were often detected in the immediate vicinity of the
disturbed samples .and cuttings. Organic contaminants in the air,
as measured by the OVA and PID, tended to behave as if heavier
than the ambient air and would dissipate quickly into the
atmosphere.
Particulate transport in air was not observed to be a
problem as dust monitoring equipment (Mini-Ram) never indicated
any increase of dust concentrations above background levels even
during field tasks which disturbed the soil. " At no time during
the field investigations did high winds reach the surface through
the trees which surround the disposal area, nor was dust a
problem.
IV. SUMHARY OF SITE HUMAN HEALTH RISKS
As part of the RI/FS process, EPA conducted an analysis to
identify human health and environmental risks that could exist if
no action were taken at the Site. This analysis, completed in
accordance with the NCP, is referred to as a baseline risk
assessment. This assessment provides the basis for taking action
and indicates the exposure pathways -that need to be addressed by
the remedial action.
In general, a baseline risk assessment is performed in four
steps: (1) data collection and evaluation, (2) the exposure
assessment, (3) the toxicity assessment, and (4) risk
characterization. This section of the ROD will summari-ze the
result of each of these steps.
A. Data Collection and Evaluation
The data collected and described in the previous section
were evaluated for use in the baseline risk assessment. This
evaluation involves reviewing the quality of the data and
determining which data are appropriate to use to quantitatively
35
-------
estimate the risks associated with Site soil, sediment, surface
water, and ground water-.
Based on the soil sampling data, the area of highest soil
contamination is the bermed disposal area from the surface to a
depth of two feet. The analytical results from samples collected
in this area were used to estimate the soil exposure point
concentrations for use in the baseline risk assessment. The
exposure point concentrations are upper 95th percentile
confidence limits of the arithmetic average concentrations of
this data set. These values are presented in Table 5.
For surface water and sediment, all data from samples
collected in the intermittent stream were used to calculate the
exposure point concentrations. As with the Site soil, the area
of groundwater contamination is best represented by samples
collected from monitoring wells within the bermed disposal area.
These data were used to calculate the groundwater exposure point
concentrations. For both soil and groundwater, exposure to
contaminants, particularly VOCs, could occur through inhalation
of air or vapors. As part of the baseline risk assessment,
exposure point concentrations were also calculated for these
pathways.
B. Exposure Assessment
There are three basic steps involved in an exposure
assessment: 1) identifying the potentially exposed populations,
both current and future, 2) determining the pathways by which
these populations could be exposed, and 3) quantifying the
exposure. Under current Site conditionst the populations that
could potentially be exposed to contaminants in soil, sediment,
and surface water are primarily visitors/trespassers. The bermed
disposal area can be accessed by a dirt road approximately 1,200
feet in length from Route 33. A locked cable located at the
half-way point restricts vehicular access; however, there are no
barriers to pedestrian access. There is evidence that the area
is used for target shooting and other recreational activities
such as hiking and hunting. The potential pathways for current
exposure include: 1) ingestion of soils, sediment, and/or surface
water, 2) dermal contact with the soils, sediment, and/or surface
water, and 3) inhalation of airborne soil vapors.
EPA believes that residential development is a potential
future use of the Site. The proximity of the Site to Richmond,
the continued growth occurring in the Richmond area, and the
continued construction of new homes in the vicinity of the Site
make the potential for future residential use a reasonable
assumption. The land use currently in the vicinity of the Site
is rural residential. The Hanover County Comprehensive Plan does
not propose any changes in the vicinity of the Site that would
attract more intense residential development (i.e., public sewer
36
-------
Table 5 - Reasonable Maximum Exposure Point Concentrations
Contaminants
Acetone
Aldrin
Aluminum
Antimony
Aroclor 1248
Aroclor 1254
Aroclor 1260
Benzene
Benzoic Acid
Beryllium
Bis(2-chloroethyl)
ether
Bis(2- ethyl
hexyl)phthalate
2-Butanone
Cadmium
Chromium (total)
Copper
Oibutyl Phthalate
1,4-
Dichlorobenzene
1,1-Dichloroethane
1 ,2-Dichloroethane
1,1-Dichloroethene
1 ,2-Dichloroethene
Soil
Ingestion/
Dermal
Contact
(mg/kg)
6.56E-012
4.63E-04
1.04E+04
1.54E+01
1.06E+01
1.26E-01
3.30E+01
2.40E-01
6.71 E-01
4.66E+02
3.93E-01
1.02E-00
9.80E+01
1.42E+03
1.23E+01
3.90E-02
Inhala-
tion of
Vapors
(mg/m3)
4.77E-06
5.35E-14
4.28E-07
2.61E-09
2.98E-1 1
5.48E-08
3.54E-11
3.00E-09
2.17E-03
9.34E-11
1.65E-07
1.91E-07
2.34E-08
Sediment
Ingestion/
Dermal
Contact
(mg/kg)
3.36E+03
1.47E+00
1.00E+00
5.03E+00
5.11E-02
5.39E-01
8.58E+00
3.57E-01
3.40E+01
1.94E+02
8.92E-01
Surface
Water
Ingestion/
Dermal
Contact
(mg/L)
1.80E+00
4.63E-03
3.45E-03
3.84E-04
4.46E-04
1.69E-03
1.56E-02
4.41 E-01
Groundwater
IngestkxV
Dermal
Contact
(mg/L)
1.31E-05
7.01 E-02
7.29E-04
3.70E-02
2.44E-03
1.31 E-02
1.61 E-02
5.14E+00
4.57E-04
3.70E-03
6.82E-03
8.21 E-04
5.97E-03
1.54E-02
1.91E-03
5.58E-02
Inhalation
of Vapors
(mg/m3)
6.80E-06
2.73E-03
5.72E-01
9.12E-02
5.68E-03
9.76E+00
9.32E-03
_8.28E-02
1.84E-01
2.80E-02
7.96E-01
2 Concentrations are presented using scientific notation. A value expressed as 1 .OE-01 is
equivalent to 0.01, otherwise expressed as 1.0 x 10'.
37
-------
Table 5 - Reasonable Maximum Exposure Point Concentrations
Contaminants
1,2- •
Dichloropropane
Dieldrin
Endrin Aldehyde
Ethylbenzene
Heptaclor Epoxide
Alpha-BHC
Gamma-BHC
Delta-BHC
Iron
Isophorone
Lead
Manganese
Methyl Isobutyl
Ketone
Nickel
N-Nitro
sodiphenylamine
Tetrachoroethene
Toluene
1,1,2-
Trichloroethane
Trichloroethene
Vinyl Chloride
Xylenes (total)
Zinc
Soil
Ingestion/
Dermal
Contact
(mg/kg)
2.09E-04
6.93E-03
2.31 E+00
3:10E-04
6.18E-03
2.17E-03
3.67E-03
1.01E+04
1.65E-01
5.72E+02
3.03E+01
2.89E-02
4.02E+00
1.46E-01
4.95E+01
5.31 E-01
1.28E-03
1.50E+01
4.13E+02
Inhala-
tion of
Vapors
(mg/m3)
6.72E-14
9.38E-06
2.77E-10
4.18E-11
2.71 E-11
5.36E-13
1 .20E-07
3.21 E-06
3.13E-05
9.47E-04
2.45E-05
1.29E-07
5.61 E-04
Sediment
Ingestion/
Dermal
Contact
(mg/kg)
4.40E+03
3.40E+02
1.15E+01
2.32E+00
4.29E+01
Surface
Water
Ingestion/
Dermal
Contact
(mg/L)
1.53-1-00
1.11E-01
9.73E-02
7.99E-03
4.17E-04
6.50E-04
8.38E-01
Groundwater
Ingestion/
Dermal
Contact
(mg/L)
3.89E-03
9.73E-06
1.36E-05
1.90E-02
2.77E-05
2.29E-05
8.31 E-04
4.80E+00
2.35E-03
1.85E-02
1.22E+00
1.51 E-01
3.94E-C3
3.85E-01
1.84E-02
1.31E-03
1.21E-02
2.33E-01
3.33E-02
Inhalation
of Vapors
(mg/m3)
4.96E-02
1.51E-07
2.0'S.OI
1 .'-' 04
5.123-05
2.44E-04
5.88E-04
6.56E-01
4.48E-02
5.60E+00
1.98E-01
1.65E-02
2.15E-01
3.18E+00
33
-------
and water);.nor does che plan advocate changes that would
discourage continued construction of rural single-family homes
(i.e., targeted future commercial or industrial use). Any homes
constructed in the vicinity of the Site would rely on private
drinking wells since public water is not available. The
potential pathways for exposure to Site contaminants under a
future residential use scenario would include those listed
previously under current use as well as pathways associated with
use of contaminated groundwater (i.e., ingestion of drinking
water, dermal contact during showering, and inhalation during
showering).
In order to quantify the potential exposure associated with
each pathway, assumptions must be made with respect to the
various factors used in the calculations. Table 6 summarizes the
values used., in the baseline risk assessment.
C. 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 in 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. It
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
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
the purpose of che 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
-------
Table 6 - Reasonable Maximum Exposure Assessment Factors
Exposure Factors
Current Site Visitor
Adult
(age > 16)
Adolescent
(age 6-16)
Child
(age <6)
Future Site Resident
Adult/Adolescent
(age >6)
Child
(age <6)
INGEST1ON EXPOSURE PATHWAY
Ingestion Rate:
. Soil/Sediment
Surface Water
Drinking Water
Exposure Frequency:
Soil
Sediment
Surface Water
Drinking Water
1 00 mg/day
0.01 liters/day
1 5 days/year
1 5 days/year
1 5 days/year
1 00 mg/day
0.01 liters/day
50 days/year
50 days/year
50 days/year
200 mg/day
0.01 liters/day
15 days/year
1 5 aays/year
15 days/year
1 00 mg/day
0.01 liters/day
2.0 liters/day
350 days/year
1 5 days/year
1 5 days/year
350 days/year
200 mg/day
0.01 liters/day
1.0 liters/day
350 days/year
50 days/year
50 days/year
350 days/year
DERMAL CONTACT EXPOSURE PATHWAY
Skin Surface Area
Available for Contact:
Soil/Sediment/
Surface Water
Shower Water
Soil/Sediment to Skin
Adherence Factor
Exposure Time:
Surface Water
Shower Water
Exposure Frequency:
Soil
Sediment
Surface Water
Shower Water
5,300 cm2
1 .0 mg/cm2
1 hour/day
1 5 days/year
1 5 days/year
1 5 days/year
3,800 cm2
1 .0 mg/cm2
1 hour/day
50 days/year
50 days/year
50 days/year
r
2,000 cm2
1 .0 mg/cm2
1 hour/day
15 days/year
1 5 days/year
1 5 days/year
5,300 cm2
20,000 cm2
1 .0 mg/cm2
1 hour/day
0.2 hours/day
350 days/year
1 5 days/year
1 5 days/year
350 days/year
2,000 cm2
7,000 cm2
1 .0 mg/cm2
1 hour/day
0.2 hours/day
350 days/year
50 days/year
50 days/year
350 days/year
INHALATION EXPOSURE PATHWAY
Inhalation Rate:
Soil Vapor
Water Vapor
Exposure Time:
Soil Vapor
Water Vapor
Exposure Frequency:
Soil Vapor
Water Vapor
1.4 rrrVhour
1 hour/day
1 5 days/year
1 .7 rrrVhour
1 hour/day
1 5 days/year
1.3 rrrVhour
1 hour/day
1 5 days/year
0.83 m3/hour
0.83 m3/hour
24 hours/day
0.2 hours/day
350 days/year
350 days/year
0.63 m3/hour
0.63 rtvVhcur
24 hours/day
0.2 hours/day
350 days/year
350 days/year
40
-------
Table 6 - Reasonable Maximum Exposure Assessment Factors
Exposure Factors
Current Site Visitor
Adult
(age >16)
Adolescent
(age 6-1 6)
Child
(age <6)
Future Site Resident
Adult/Adolescent
(age >6)
Child
(age <6)
EXPOSURE ASSESSMENT CONSTANTS
Exposure Duration
.Body Weight
Averaging Time:
Carcinogens
Nbncarcinogens
30 years
70kg
70 years
30 years
10 years
42kg
70 years
1 0 years
6 years
15kg
70 years
6 years
30 years
70kg
70 years
30 years
6 years
15kg
70 years
6 years
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.
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)~1, 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 (e.g., 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 7.
Reference doses 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
'lifetime daily exposure levels for humans, including sensitive
individuals. Estimated intakes of contaminants of concern'from
human epidemiological studies or animal studies to which
uncertainty factors have been applied account for the use of
animal data to predict effects on humans. Reference doses used
in the baseline risk assessment are presented in Table 7.-
41
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Table 7 - Slope Factors and Reference Doses
Chemical
Acetone
Aldrin
Antimony
Aroclor 1248
Aroclor 1 254
Aroclor 1 260
Benzene
Benzole acid
Beryllium
Alpha-BHC
Gamma-BHC
Bis(2-chloro
ethyl) ether
Bis(2-ethyl
hexyl)phthalate
2-Butanone
Cadmium
Chromium(VI)
Copper
Di butyl
phthalate
• 1,4-Dichlorc
benzene
1,1-
Oichloroethane
1.2-
Dichloroethane
1.1-
Dichloroethene
1.2-
Dichloroethene
1 ,2-Dichloro-
propane
Dieldrin
Endrin
Slope Factors (mg/kg-day) '
Oral
17
• 7.7
7.7
7.7
0.029
4.3
6.3
1.3
1.1
0.014
ND
0.024
ND
0.091
0.6
0.068
16
Inhalation
17
7.7
7.7
7.7
0.029
8.4
6.3
1.3
1.1
0.014
6.3
0.024
ND
0.091
0.175
0.068
16
Class
82
B2
B2
B2
A
B2
B2
B2
B2
B2
81
C
C
B2
C
82
82
Reference Dose (mg/kg-day)
Oral
Chronic
0.10
0.00003
0.0004
4.0
0.005
0.0003
0.02
0.60
0.0005
0.005
0.0371
0.10
0.2
0.1
0.009
0.02
0.00005
0.0003
Subchronic
1.0
0.00003
0.0004
4.0
0.005
0.003
0.02
0.60
0.0005
0.02
0.0371
1.0
0.2
0.1
0.009
0.20
-
0.00005
0.0003
Inhalation
Chronic
0.10
0.00003
0.0004
4.0
0.005
0.0003
0.02
0.29
0.0005
ND
0.10
0.2
0.14
0.009
0.02
0.001 1
0.00005
0.0003
Subchronic
1.0
0.00003
0.0004
4.0
0.005
0.003
0.02
0.29
0.0005
ND
t
1.0
0.2
1.4
0.009
0.20
0.0037
0.000005
0.0003
-------
Table 7 - Slope Factors and Reference Doses
Chemical
Ethylbenzene
Heptachlor
epoxide
Isophorone
Lead
Manganese
Methyl isobutyl
ketone
Nickel
N-Nitroso
diphenylamine
Tetrachlorb-
ethene
Toluene
1,1,2-
Trichloroethane
Trichloroethene
Vinyl chloride
Xylenes
Zinc
Slope Factors (mg/kg-day) '
Oral
9.1
0.0009
5
--
--
0.0049
0.052
0.056
0.01 1
1.9
Inhalation
9.1
0.00095
--
ND
--
0.002
0.056
0.006
0.30
Class
B2
C
62
D/--
82
B2
C
B2
A
Reference Dose (mg/kg-day)
Oral
Chronic
0.10
0.000013
0.2
0.005
0.05
0.02
0.01
0.2
0.004
2.0
0.3
Subchronic
1.0
0.000013
2.0
0.005
0.5
0.02
0.1
2.0
0.04
4.0
0.3
Inhalation
Chronic
0.29
0.000013
0.2
0.0001
0.023
0.02
0.01
0.12
0.004
2.0
0.3
Subchronic
0.29
0.000013
2.0
0.0001
0.23
0.02
671
0.6
0.04
4.0
0.3
Key: ND - Not determined
Class = EPA Weight-Of-Evidence Class for Carcinogenicity
A Human Carcinogen - sufficient evidence from epidemiological studies to support a
causal association between exposure and cancer
B Probable Human Carcinogen -
B1 • At least limited evidence of carcinogenicity to humans from epidemiological studies
82 • Usually a combination of sufficient evidence of carcinogenicity in animals and
inadequate evidence of carcinogenicity in humans
C Possible Human Carcinogen - limited evidence of carcinogenicity in animals in the
absence of human data
D Not Classified - inadequate evidence of carcinogenicity in animals
"43
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D. Human Health Effects
The health effects of the Site contaminants that are most
associated with the unacceptable risk levels are summarized
below. in most cases, the information in the summaries is drawn
from the Public Health Statement in the Agency for Toxic .
Substances and Disease Registry's (ATSDR) toxicolcgical profile
for the chemical.
Antimony: Antimony can enter the body by absorption from the
gastrointestinal tract following ingestion of food or water
containing antimony, or by absorption from the lungs after
inhalation. Ingestion of high doses of antimony can result in
burning stomach pains, colic, nausea, and vomiting. Long-term
occupational inhalation exposure has caused heart problems,
stomach ulcers, and irritation of the lungs, eyes, and skin.
The critical or most sensitive noncarcinogenic effects of
exposure to antimony are shortened life span, reduced blood
glucose levels, and altered cholesterol levels. Existing data
suggest that antimony may be an animal carcinogen but are not
sufficient to justify a quantitative cancer potency estimate at
this time. In laboratory rats, inhalation of antimony dust can
increase the risk of lung cancer. However, there is no evidence
of increased risk of cancer to animals from eating food or drink-
ing water containing antimony. It is not known whether antimony
can cause cancer in humans.
Benzene: Benzene is readily absorbed by inhalation and
ingestion, but is absorbed to a lesser extent through the skin.
Most of what is .known about the human health effects of benzene
exposure is based on studies of workers who were usually exposed
for long periods to high concentrations of benzene. Benzene is
toxic to blood-forming organs and to the immune system.
Excessive exposure (inhalation of concentrations of 10 to ICO
ppm) can result in anemia, a weakened immune system, and
headaches. Occupational exposure to benzene may be associated
with spontaneous abortions and miscarriages (supported by limited
animal data), and certain developmental abnormalities such as low
birth weight, delayed bone formation, and bone marrow toxicity.
Benzene is classified as a Group A human carcinogen based on
numerous studies documenting excess leukemia mortality among
occupationally exposed workers.
Beryllium: The respiratory tract is the major target of
inhalation exposure to beryllium. Short-term exposure can
produce lung inflammation and pneumonia-like symptoms. Long-rerm
exposure can cause berylliosis, an immune reaction characterized
by noncancerous growths on the lungs. Similar growths can appear
on the skin of sensitive individuals exposed by dermal contact.
•Epidemiological studies have found that an increased risk of lung
cancer may result from exposure to beryllium in industrial
settings. In addition, laboratory studies have shown that
44
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breaching beryllium causes lung cancer in animals. However, it
is not clear what cancer risk, if any, is associated with
ingestion of beryllium. EPA has classified beryllium as a Group
82 probable human carcinogen based on the limited human evidence
and the animal data.
Bis(2-chloroethyl)ether (BCEE): BCEE enters the body easily
after being ingested or inhaled, and crosses the skin easily
after dermal contact. People exposed to the vapors of BCEE
report that they are highly irritating to the ncse and eyes.
Animals exposed to high amounts of BCEE by inhalation can sustain
lung damage sometimes leading to death. There is no information
on the effects on other organ systems or the effects of low doses
of. BCEE over long periods of time. BCEE causes cancer in mice.
Mice exposed to low levels of BCEE orally for long periods of
time develop liver tumors. However, there is no excess cancer in
rats when they are treated similarly. There are no cases of
cancer in humans attributed to BCEE. EPA classifies BCES as a
Group B2 probable human carcinogen based on the studies on mice.
Bis-(2-ethylhexyl)phthalate (DEHP): DEHP can enter the body
following exposure by breathing air or eating food or water that
contain DSHP. The most likely route of human exposure is through
food. DEHP can leach into foods from plastics used in food
processing and storage. Most of what is known about the health
effects of DEHP comes from studies of laboratory mice and rats.
The very low levels to which humans may be routinely exposed have
not been shown to cause adverse effects; however, liver disease
and reproductive effects have been associated with DEHP exposure
to laboratory animals. DEHP has been shown to -cause liver cancer
in rats and'mice. However, because there have been no studies of
DEHP carcinogenic effects in humans, DEHP is classified as a
Group B2 probable human carcinogen.
2-Butanoae (Methyl Ethyl Ketone [MEK] ) -. In general, observable
effects occur only in animal studies at high doses. Health
effects resulting from inhalation or ingestion cf MEK include:
respiratory irritation, kidney and liver abnormalities,
underdeveloped offspring, and unconsciousness and death at high •
doses. Toxic effects to offspring (as an indicator) is SPA'S
critical or most sensitive effect noted. There are reports of
behavioral effects in mice and baboons at low doses of MSK.
There is very little long-term exposure data for MEK in humans
and animals. It is unknown whether MSK causes cancer in animals
or humans.
Cadmium: Cadmium can cause a number of adverse health effects.
Ingesticn of high doses causes severe irritation to the stomach,
leading to vomiting and diarrhea, while inhalation can lead to
severe irritation of the lungs and may cause death. People have
committed suicide by drinking water containing high levels of
cadmium. There is very strong evidence that the kidney is the
45
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main target organ of cadmium toxicity following chronic exposure.
Long-term ingestion of cadmium has caused kidney damage and
fragile bones in humans. Long-term human exposure by the
inhalation route may cause kidney damage and lung disease such as
emphysema. The most sensitive or critical effect of cadmium
exposure is high concentrations of protein in urine, indicative
of abnormal kidney function. Long-term inhalation of air
containing cadmium by workers is associated with an increased
risk of lung cancer. Laboratory rats that breathe cadmium have
increased cancer rates. Studies of humans or animals have not
demonstrated increased cancer rates from .eating or drinking
cadmium. EPA classifies cadmium as a Group Bl, probable human
inhalation carcinogen based on occupational studies.
Chlordane/Heptachlor/Heptachlor Epoxide: Chlordane, heptachlor,
and heptachlor epoxide can be absorbed by the body through dermal
contact, inhalation of particulates in ambient air, and ingestion
of. contaminated food or soils. These substances may remain
stored for months or years in the blood plasma o'r the body fat of
the liver, spleen, brain, and kidneys. Heptachlor epoxide can
also pass directly from a mothers blood to an unborn baby through
the placenta. Little data are available on the adverse health
effects of chlordane, heptachlor, and heptachlor epoxide exposure
in humans. Symptoms associated with human overexposure to those
compounds include headache, dizziness, lack of coordination,
irritability, weakness, and convulsions. In humans, an acute
oral lethal dose of chlordane is estimated to be between 25 and
50 mg/kg. Experimental studies exploring the health effects on
animals exposed to various levels of chlordane showed an
association between exposure and immunologic dysfunction,
reproductive dysfunction, nervous system damage, liver damage,
convulsions, liver cancer, and death. The lethal dose of
chlordane in rats is estimated to be between 85'and 560 mg/kg.
Some occupational epidemiology research suggests an increased
cancer risk associated with human exposure to chlordane. Chronic
oral treatment with chlordane and heptachlor has resulted in
significant" increases in hepatocellular carcinomas in mice. EPA
has classified chlordane, heptachlor, and heptachlor epoxide as
Group B2 probable human carcinogens.
Chromium: There are two major forms of chromium, which differ in
their potential adverse health effects, found in the environment.
One form, chromium VI (chromium 6"1"} , is irritating; short-term,
high-level exposure can result in adverse effects at the site of
contact, causing ulcers of the skin, irritation and perforation
of the nasal mucosa, and irritation of the gastrointestinal
tract. Minor to severe damage to the mucous membranes of the
respiratory tract and to the skin have resulted from occupational
exposure to as little as 0.1 mg/m3 chromium VI compounds.
Chromium VI may also cause adverse effects in the kidney and
liver. Long-term occupational exposure to low levels of chromium
46
-------
VI compounds has been associated with lung cancer in humans.
Chromium VI is classified by EPA as a Group A known human
carcinogen based on evidence from epidemiological studies. The
second form, chromium III (chromium 3+), does not result in
these effects and is the form thought to be an essential
nutrient. The only effect observed in toxicological studies of
chromium III is a decrease in liver and spleen weights in rats.
This effect was used as the basis for the RfD.
Copper: Copper may enter the body by breathing air, drinking
water, eating food containing copper, and by skin contact with
soil, water, and other copper-containing substances. Copper is
an essential element at low-dose levels but may induce toxic
effects at high-dose levels. The critical or most sensitive
effect is gastrointestinal irritation. The National Academy of
Science has recommended 2 to 3 mg/day of copper as a safe and
adequate daily intake. Long-term overexposure to copper dust can
irritate the nose, mouth, and eyes and cause headaches,
dizziness, nausea, and diarrhea. Ingestion of high
concentrations of copper can cause vomiting, diarrhea, stomach
cramps, and nausea. Very young children are particularly
sensitive to ingested copper. Liver and kidney damage and
possibly death may result from long-term exposure. In general,
the seriousness of health effects of copper increase as the level
and duration of exposure increases. Copper is not known to cause
cancer or birth defects.
1,2-Dichloroetbane (1,2-OCA): The lungs, heart, liver, and
kidneys are the organs primarily affected in both humans and
animals exposed to 1,2-DCA. Short-term exposure to 1,2-DCA in
air may result in an increased susceptibility to infection and
liver, kidney, and/or blood disorders. Effects seen in animals
after long-term exposure to 1,2-DCA included liver, kidney, heart
disease, and/or death. 1,2-DCA has caused increased numbers of
tumors in laboratory animals when administered in high doses in
the diet or on the skin and is classified as a Group B2 probable
human carcinogen.
1,1-Dichloroethene (1,1-DCE): 1,1-DCE usually enters the body
via inhalation and/or ingestion. It may also enter the body
through the skin. The human health effects resulting from
exposure to 1,1-DCE are unknown. In animal studies, brief
exposures to high concentrations of 1,1-DCE have caused liver,
kidney, heart damage, lung damage, nervous system disturbances,
and death. Prolonged exposure to lower concentrations of 1,1-DCE
has also produced liver damage. An increased risk for cancer was
observed in animals exposed to 1,1-DCE, as were birth defects in
the offspring of exposed pregnant animals. Based upon animal
studies, 1,1-DCE is classified as a Group C possible human
carcinogen.
47
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Polychlorinated Biphenyls (PCBs): PCBs can enter the body when
fish, other foods, or water containing PCBs are ingested, when
air that contains PCBs is breathed, or when skin comes in contact
with PCBs. Skin irritations characterized by acne-like lesions
and rashes and liver effects were the only significant adverse
health effects reported in PCB-exposed workers. Epidemiological
studies of workers occupationally exposed to PCBs thus far have
not found any conclusive evidence of an increased incidence of
cancer in these groups. Effects of PCBs in experimentally
exposed animals include liver damage, skin irritations, death,
low birth weights, and other reproductive effects. Some strains
of rats and mice that were fed PCB mixtures throughout their
lives showed increased incidence of cancer of the liver and other
organs. Based on these animal studies, EPA has classified PCBs
as Group B2 probable human carcinogen.
1,1,2-Trichloroethane: No case reports or epidemiological
studies regarding human occupational or environmental exposure
are available. Studies with various animals, however, suggest
that 1,1,2-TCA can enter the body following inhalation of
contaminated air, ingestion of or dermal contact with
contaminated drinking water, or through dermal contact with the
solvent itself. 1,1,2-TCA is a central nervous system
depressant. It has narcotic properties and. can act as a local
irritant to the eyes, nose, and lungs. 1,1,2-TCA is also
associated with both liver and kidney damage. 1,1,2-TCA may be
carcinogenic. It caused liver tumors in mice, but not rats,
chronically fed 1,1,2-TCA. No other studies have shown evidence
of carcinogenicity, however. Further studies with rats using
higher concentrations and other species would improve the
knowledge of 1,1,2-TCA carcinogenicity. Based upon the present
evidence from animal studies, EPA considers 1,1,2-TCA a Group C -
possible human carcinogen.
vinyi Chloride (VC): VC may cause adverse health effects
following exposure by inhalation, ingestion, or by dermal or eye
contact. VC inhalation can cause dizziness or sleepiness.
Breathing very high levels of VC can cause unconsciousness and in
some cases death. On skin, exposure to liquid VC can cause
burns. Noncarcinogenic effects associated with long-term
occupational VC exposure include hepatitis-like changes in the
liver, immune reactions, and nerve damage. VC has been shown to
cause liver and lung cancer in rats and liver cancer in workers
occupationally exposed to air concentrations in the range of 25
ppm to greater than 200 ppm. Based on this evidence, EPA has
classified VC as a Group A human carcinogen.. Air standards as
low as 1 ppm are specified for occupational exposure to VC in
many countries.
Zinc: Zinc appears to be toxic only at levels at least 10 times
higher than the recommended daily allowance. Symptoms of
overexposure may include severe diarrhea, stomach cramping,
48
-------
nausea, and vomiting. Serious damage to the digestive system car.
occur if too much zinc is ingested over a long period of time.
Ingesting too much zinc can cause deficiency in other nutrients
such as iron (anemia) and copper. Anemia is the critical effect
or most sensitive effect caused by zinc overexposure. Inhalation
of zinc fumes or dusts has been associated with a condition
called "metal fume fever" characterized by flu-like symptoms
including throat irritation, body aches, weakness, and fatigue.
Zinc is not thought to cause cancer or.birth defects. MRLs are
not available for zinc because zinc is an essential nutrient.
E. 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 life-time as a result of exposure to the
contaminant. These probabilities are generally expressed in
scientific notation (e.g., IxlO"6, otherwise expressed as IE"6).
An excess lifetime cancer risk of IxlO"6 indicates that, as a
reasonable maximum estimate, an individual has a 1 in 1,000,000
chance of developing cancer as a result.of site-related exposure
to a carcinogen over a 70-year lifetime under the specific
exposure conditions at the site. The generally acceptable excess
cancer risk range, as defined by Section 300.430 (e)(2)(i)(A)(2)
of the NCP, is between 1.0 x 10"4 to 1.0 x 10"6.
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. Any media with.an HI greater than 1.0 has
the potential to adversely affect health.
The baseline risk assessment estimates the reasonable
maximum octal lifetime cancer risks for future Site residents to
be 2.0 x 10"3 for adults and 1.2 x 10"3 for children under six
years old. These risks exceed the acceptable risk range of 10"4
to IO'6 established in Section 300.430 (e) (2) (i) (A) of the NC?.
Table 8 summarizes the baseline risk assessment calculations for
carcinogenic risk to individuals who would experience a
reasonable maximum exposure to Site contaminants. The baseline
risk assessment also calculates the risks to individuals who
would experience an average exposure to Site contaminants. Under
49
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average conditions, future Site residents would experience a
total lifetime cancer risk of 1.4 x 10~4 for adults and
4.1 x 10~4 for children under six years old.
The baseline risk assessment estimates the hazard index for
noncarcinogenic effects for future Site residents to be 8.4 for
adults and 19 for children under six years old, under reasonable
maximum exposure (RME) conditions. These risks exceed 1.0, which
is the acceptable hazard index level. Table 9 summarizes the
hazard indices for noncarcinogenic risk to individuals who would
experience a reasonable maximum exposure to Site contaminants.
Under average exposure conditions, future Site residents would
experience a hazard index for noncarcinogenic effects of 2.4 for
adults and 7.9 for children under six years old.
VII. SUMMARY OF SITE ECOLOGICAL RISKS
The ecological assessment (EA) focuses on existing and
potential risk posed by Site-related contaminants to nearby
natural habicats and associated flora and fauna. It provides
information pertinent to selection and development of the
remedial actions. Potential contamination via surface water
runoff from the Site led to the selection of the unnamed
ephemeral tributary to Black Haw Branch up to the second logging
road for investigation.
Ecological receptors and potential exposure pathways were
evaluated for inclusion in the ecological assessment on the basis
of the Site contaminants, affected media identified, and the
characteristics of receptors. The following exposure pathways
were chosen for evaluation in the risk assessment:
• Aquatic biota in the unnamed ephemeral tributary and semi-
aquatic- species were chosen due to their potential exposure
to elevated metal levels and PCB concentrations in the sedi-
ment and surface water.
• Plants growing on top of and along the edge of the Site were
chosen due to the observation of stressed vegetation in some
areas. This exposure pathway was incorporated into the
secondary consumer pathway.
• Secondary consumers, especially small mammals using the
Site, were chosen due to their potential exposure to
elevated levels of metals, PCBs, and phthalates in the soil.
• Migratory birds using the Site were chosen due to their
potential exposure to elevated levels of PCBs and metals
contaminants in the soil and sediment.
50
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Page I of 2
Table 8
SUMMARY OF ESTIMATED EXCESS CANCER RISKS
ASSOCIATED WITH THE H&H SITU - RME CASE
Kx|iosure Scenario
Silc visilors
TOTAL
1 u( ure site residents
Exposure Media
Soil
Air (vapor*)
Strum teJinicnl
Stream surface water
tiroundwatcr
Soil
Air (vapors)
Receptor*
AdulU
3.1 * 10 J
1.8 i 10 '
40 x 10*
2.5 x lO-$
60 x 10 5
I.I x 10°
83 x 10-*
5.8 x 10'7
Children
(1-6 year-old)
l.8x 10 5
1 5x 10 9
1.8 x 10*
8.9 x JO*
2.9 x 10 $
5.3 x 10 4
6.0 x 10 4
4.1 x I07
Adolescents
(6-16 year-old)
44 x 10 J
40 x 10 9
5.4 x 10*
3.4 x 10 S
83 x 10 $
--
--
Kisk Contributions by Exposure
Route*
Soil ingcslion - 18%
Dermal contact with (oil - 82%
-
Incidental ingcilion • 8%
Dermal contact - 92%
Incidental ingeslion - 0.4%
Dermal contact - 99%
Drinking water - 68 %
Dermal contact with water - 10%
Inhalation of vapors in ihowcr - 22%
Incidental ingeilion - 25%
Dermal contact • 75%
...
Risk Contributions by Chemical*
PCBi 99%
PCBj 71%
I.I.2-TCA 28%
PCBi >99%
PCBs - >99%
Vinyl chloride 32%
Bu(2 chloruclhylKlher • 25%
PCBs 17%
Beryllium 12%
Benzene - 3%
1.2-DCA • 3%
I.I-DCE 2%
PCBs 99%
l-CBj 71%
1.1,2 TCA 28%
-------
Page 2 of 2
recycled paper
Table 8 (Cont.)
SUMMARY OP ESTIMATED EXCESS CANCER RISKS
ASSOCIATED WITH THE H&ll SITE - RME CASE
Kxposure Scenario
Future tile rciidenli
(Conl )
TOTAL
Exposure Media
Stream sediment
Stream turfacc water
Receptors
• Adults
4.0 x 10*
2.5 x 10 J
2.0 x 10 3
Children
99%
a These columns are independent of each other. Both refer to the total receptor risks for the receptor with the highest estimated cancer risk.
Source: Ecology and Environment, Inc. 1992.
-------
Page I of I
Table 9
SUMMARY OF ESTIMATED HAZARD INDICES
FOR NONCARCINOGENIC EFFECTS ASSOCIATED
WITH THE H&H SITE - RME CASE
Exposure Scenario
Silc visitors
TOTAL
Future site residents
TOTAL
Exposure Media
Soil
Air (vapon)
Stream sediment
Strum surface water
Croundwalcr
Soil
Air (vapors)
Stream sediment '
Stream surface water
Receptors
Adults
3.9 x 10 3
2.1 x 10 5
25 x 10 4
48 x 10 *
0005
82
l.8x 10 '
70 x 10 3
25 x 10-*
48 x 10 4
84
Children
(1-6 year-old)
32 x 10 2
3.6 x 10 5
1 6x I03
I7xl03
004
17.3
15
99 x 10°
5.4 x 10 3
5.6 xlO'3
19
Adolescents
(6-16 year-old)
2.1 x 10 2
1.4 x IO"4
1.4 x 10 3
2.4 x 10 3
002
-
--
-
--
Signincant Hazard Index
Contributions by Exposure Route*
-
-
-
--
Drinking water - 96%
Inhalation of vapon - 4%
Incidental ingestiun - 99%
Dermal contact - 0.2%
--
-
--
Significant Hazard Index
Contributions by Chemical*
.-
-.
Manganese • 94%
2-Bulanone - 5%
Antimony • 34%
Copper - 33%
Bis(2-clhylhexyl)phihal«le • 20%
Manganese • 5%
Chromium - 4%
Cadmium • 2%
Zinc • 1 %
a These columns arc independent of each other. Both refer to the total receptor risks for the receptor with the highest hazard index.
Source: Ecology and Environment, Inc. 1992.
-------
Receptors and exposure pathways excluded from evaluation in
the risk assessment were upland tertiary consumers and top
carnivores due to the size ofxthe Site relative to the necessary
home range for these species. The potential for significant
exposure of these taxa to Site contaminants is considered
minimal.
Based on these considerations, and on the potential exposure
pathways and receptors identified in the previous section,
indicator species and assessment endpoints were selected.
Ubiquitous indicator species were chosen based on their habitat
requirements and the likelihood they would occur on the Site.
The indicator species include:
• Amphipods (Hyalella aztsca) and midges (Chironomus tentans)
representing aquatic biota expected to occur in the unnamed
ephemeral tributary;
• The green frog (Rana clamitans melanota) representing semi-
aquatic and terrestrial wildlife that are expected to occur
in the area and which may depend on the tributary for a
fraction of their food or habitat needs;
• The meadow vole (Microtus pennsylvanicus) representing small
mammals that are expected to occur on the Site; and
• The American robin (Turdus migratorius) representing
migratory birds that are expected to occur on the Site.
Assessment endpoints for the indicator species are the
estimated effects of Site contaminants on survival, reproduction,
growth, or other critical effects. These indicator species were
chosen because of their potential exposure and susceptibility to
adverse effects of Site contaminants and available toxicological
data for these taxa.
A. Selection of Contaminants of Ecological Concern
Copper, lead, and zinc were found at elevated concentrations
in surface water samples collected up to the second logging road
along the unnamed ephemeral tributary that drains the disposal
area. Beyond the second logging road, only lead and zinc are
present, though at concentrations substantially lower-than the
samples collected before the second logging road. Aroclor 1260
was detected in six of the 15 surface water samples collected
from the unnamed ephemeral tributary prior to the second logging
road. Therefore, the EA focused on copper, lead, zinc, and
Aroclor 1260 in surface water.
In sediment, lead and copper were found in elevated
concentrations along the unnamed ephemeral tributary immediately
below the disposal area and downstream to the second logging
54
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road. Arsenic, aluminum, chromium, and zinc also were present at
elevated concentrations along the same portion of the tributary.
Of these six contaminants, lead and copper are present in
substantially higher concentrations and are more widely
distributed (i.e., they are present in elevated concentrations in
more of the samples collected from the above-mentioned location).
Therefore, even though all six metals are of concern, lead and
copper received greater attention in the EA. Aroclor 1260 was
detected in 14 of the 22 sediment samples collected in the
unnamed ephemeral stream and was also addressed in the EA.
In soil, copper, lead, and zinc were found at concentrations
above the upper limit of 90th percentile of common range found in
eastern United States soils. Aluminum, arsenic, and chromium
were also found at elevated concentrations in all surface soils
collected on Site, and one s.urface soil collected downgradient of
the Site. One sample, SS-6A, contained chromium at a
concentration above the upper limit of 90th percentile of common
range found in eastern United States soils. While these
inorganics are important, copper, lead, and zinc were the focus
of the EA because of their toxicity and elevated concentrations
compared to the other inorganics.
PCBs, especially Aroclor 1260 and 1248, were detected in
soil at concentrations greater than the EPA "Region 3 risked-based
concentrations for residential soil. Bis(2-ethylhexyl) phthalate
was found at concentrations above the background sample
collected. However, none of the samples exceeded the EPA Region
3 risk-based concentrations for residential soils. In contrast,
bis(2-ethylhexyl)phthalate was detected in 12 of the 17 soil
samples with a maximum concentration of 63,000 Mg/kg. Eleven of
the 12 samples had concentrations significantly above background
levels. PCBs and bis(2-ethylhexyl)phthalate were the focus of
the EA for organics in soil.
B. Exposure Assessment
Three metals (lead, copper, and zinc) and two organics (PCB
and bis(2-ethylhexyl) phthalate) have been identified as the
contaminants of ecological concern. Three contaminant migration
mechanisms are potentially operating to disperse these Site
contaminants further into the environment: stormwater runoff,
wind, and groundwater. Under the conditions at the Site, and
with the apparent absence of an organic carrier solvent for PCBs
and bis(2-ethylhexyl)phthalate, both the metal and organic
contaminants would be predominantly insoluble in the ground
water. Therefore, the contaminants would be more prone to bulk
migration via runoff and wind rather than by dissolution followed
by migration in groundwater. The absence and low levels of these
contaminants in the groundwater samples collected from beneath
the Site and from nearby residents corroborate this conclusion.
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Contaminants migrating via surface water runoff may be found
in the water and sediment of the unnamed ephemeral tributary to
Black Haw Branch and its associated wetland area. In this
exposure scenario, contaminants could directly migrate from the
bermed disposal area to the tributary during storms or snow melt.
These contaminants can be carried on suspended soil or sediment
particles or in solution. The pH of the surface water is acidic
and metals, especially zinc, will go into solution. This was
corroborated by elevated zinc concentrations in the filtered
surface water samples. Black Haw Branch, which receives the
tributary's water and suspended burden approximately one mile
downstream from the disposal area, would be the ultimate fate of
contaminants being transported by the tributary.
The aquatic sediment and surface water data indicate that
exposure of the tributary's aquatic biota and semiaquatic and
terrestrial wildlife to elevated contaminant concentrations does
currently not extend past the second logging road located near
samples SW-13 and SED-13. At this point, a secondary tributary
enters the intermittent stream. The sediment and surface water
metal concentration in samples immediately below the second
logging road are greatly reduced from those adjacent to the
disposal area. In sediment, the metal concentrations decrease to
background levels. PCBs appear to have migrated in sediments to
the confluence of the intermittent stream and the Black Haw
Branch. Contaminant migration via wind erosion, while possible,
is not likely assuming the dense woody vegetation surrounding the
bermed disposal area is maintained.
1. Organic Exposure Point Concentrations
A number of environmental factors affect the bioavailability
of organics in the soil, especially the amount of organic carbon
available. The sorption of organics by humic substances will be
the controlling factor in determining release, migration, and
fate of organics. For this assessment, the bioavailable fraction
for organics was determined and used as the concentration
available for uptake by receptor organisms in the soil.
While plants do readily absorb soluble organic compounds of
low molecular weight, the insolubility and size of PCBs and
phthalate would argue against substantial uptake via soil pore
water. Therefore, it was assumed for this assessment that plants
will not uptake the organic contaminants.
The geometric mean organic contaminant concentration
detected in surface water and sediments was used as the exposure
point concentration.
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2. Metals Exposure Point Concentrations
A number of environmental factors affect the bioavailability
of metals in soil. If environmental factors such as adsorption
and precipitation reactions are considered, the bioavailable
concentrations may drop by 10 to 100 fold for lead, 10 to 50 fold
for copper, and 5 to 10 fold for zinc. However, for the purposes
of this screening-level risk assessment, the bulk metal
concentrations measured at the Site will serve as a simple
estimate of exposure concentrations. The geometric average metal
contaminant concentration in unfiltered surface water and
sediments was used as the exposure point concentration.
The principal routes of potential exposure of the meadow
vole and American robin to contaminants would be via
bioaccumulation through the food chain and incidental ingestion
of contaminants in soil. For the green frog, the principal
routes of uptake of contaminants are from the water, direct
ingestion of soil, and bioaccumulation through the food chain.
C. summary of Ecological Risks and Uncertainties
The risks of Site contamination were quantified by :
calculating an HI ratio for each contaminant, pathway, and
receptor that could be quantitatively evaluated. The His were
calculated as follows:
HI = ED/TRV
where
HI = Hazard index;
ED = Estimated dosage or geometric mean concentrations
(for surface water and sediment) in medium;
TRY = Toxicity reference value.
An HI greater than one (1) would be considered presumptive
evidence of the potential for risk of chronic or acute (for
aquatic benthos only) toxicological effects to a given ecological
receptor.
The surface water acute and chronic His are 15.0 and 22.5,
respectively, for copper, 1.2 and 173.57 for PCBs, and-4.65 and
5.07 for zinc. This suggests a potential for ecological risk to
aquatic biota for both acute and chronic impacts. The lead acute
and chronic His are 0.69 and 17.94, respectively, suggesting no
acute impacts, but potential chronic impacts in surface water.
As a result, taxa receiving brief exposures to the tributary
waters (e.g., migrating waterfowl) would be a low risk, while
resident taxa may be affected).
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For amphibians, such as the green frog, exposure to copper
and lead in the sediment and surface water via the food chain or
direct contact or incidental ingestion may result in adverse
effects. The His are 3.15 and 7.62 for lead and copper,
respectively. As a result, resident biota receiving chronic
exposures to the sediment and surface water may be at risk for
toxic effects by the current copper and lead levels. HI values
for PCBs, zinc, and bis(2-ethylhexyl)phthalate were not
calculated. Toxicity reference values were not available for
these substances. The high estimated dosage value suggests that
a potential exists for adverse effects for these contaminants.
For copper and lead in the Site soil, food chain or direct
exposures may result in adverse toxicological effects for the
meadow vole and American robin. The copper His for meadow vole
and American robin are 175 and 1.69, respectively, and His for
lead are 6.30 and 14.03, respectively. Results for PCBs indicate
a potential for adverse effect for the robin (HI of 26.23), but
not the meadow vole (HI of 0.07). The HI for zinc in meadow vole
was essentially one (1) and may pose some risk while zinc poses
no potential risk for the American robin. Bis(2-ethylhexyl)
phthalate poses no risk potential to the meadow vole. The HI for
this substance was not calculated for the robin because toxicity
reference values were not available. The high estimated dosage
value suggests that a potential exists for adverse effects for
this contaminant.
The sediment His for the ephemeral tributary based on the
lowest-observed-effect level are 4.84 for copper, 6.03 for lead,
0.29 for zinc, and 497 for Aroclor 1260. These HI values
indicate that there is a high risk of some ecological impact
associated with the copper, lead, and Aroclor 1260 contamination
of the sediments and that this contamination at these levels
would be expected to impair use of the sediments by the benthic
community. This conclusion was corroborated with the chronic
toxicity tests performed on Hyalella azteca and Chironomus
tentans. The sediments were toxic to both these organisms.
Uncertainties in this assessment are associated with both
the exposure and toxicity assessments. The principal uncertainty
in the exposure assessment involves estimating the bioavailable
fraction in soils. Additional uncertainties arise from a lack of
information about incidental ingestion and dermal pathways for
wildlife. Moreover, each input variable used to derive estimated
exposures for the food chain pathway is subject to uncertainty.
Generally, the worst case was assumed to provide a conservative
estimate. Few reliable toxicity values were available for soils
and for effects of Site-related contaminants on wildlife.
Therefore, considerable uncertainties exist in the extrapolation
of toxicity values derived from surrogate species to the species
of concern. As with the exposure assessment, reasonable worst-
case assumptions were made to provide a conservative estimate.
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In general, the risk assessment is likely to overestimate rather
than underestimate the risks of adverse ecological effects at the
Site because of the conservative nature of £he assumptions used.
Quantitative exposure scenarios were developed for the
meadow vole, American robin, and green frog. Based on the
habitat and food requirements of the indicator species, each
species will exhibit a different exposure scenario. The green
frog may use the unnamed tributary and surrounding vegetation and
invertebrates for all their food and habitat requirements, while
the meadow vole and robin may use the Site and surrounding
vegetation for their food and habitat requirements.
VIII. DESCRIPTION OP ALTERNATIVES
In the Feasibility Study (FS), engineering technologies
applicable to remediating the contaminated media were screened
according to their effectiveness and implementability. Those
technologies remaining after the screening process were then
developed into remedial alternatives. The medium-specific
remedial alternatives were developed utilizing information and
data from the FS report.
Because the soil designated for remediation is apparently
acting as at least a partial source of ground water
contamination, it is appropriate to combine the soil/sediment and
ground water alternatives into comprehensive Site-wide
alternatives. The retained medium-specific alternatives
presented in the FS have been combined into the following Site-
wide alternatives:
• Alternative A: No action.
• Alternative B: Capping of contaminated soils and sediments,
limited institutional controls.
• Alternative Bl: Capping of contaminated soils and
sediments, extraction and on-site treatment of
contaminated ground water, limited institutional
controls.
• Alternative B2: Capping of contaminated soils and
sediments, in situ biological treatment of ground-water with
limited aboveground treatment.
• Alternative C: Excavation of contaminated soils and
sediments, on-site thermal desorption treatment of organics-
contaminated soils and sediments, on-site solvent extraction
treatment of metals-contaminated soils and sediments, on-
site disposal.
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Alternative Cl: Excavation of contaminated soils and
sediments, on-site.thermal desorption treatment of
organics-contaminated soils and sediments, on-site
solvent extraction treatment of metals-contaminated
soils and sediments, on-site disposal. Extraction and
on-site treatment of contaminated groundwater.
Alternative C2: Excavation of contaminated soils and
sediments, on-site thermal desorption treatment of organics-
contaminated soils and sediments, on-site solvent extraction
treatment of metals-contaminated soils and sediments, on-
site disposal, in situ biological treatment of ground water
with limited aboveground treatment.
Alternative D: Excavation and on-site thermal desorption
treatment of contaminated soils and sediments, off-site
disposal.
Alternative Dl: Excavation and on-site thermal desorption
treatment of contaminated soils and sediments, off-site
disposal, extraction and on-Site treatment of contaminated
ground water.
Alternative D2: Excavation and on-site thermal desorption
treatment of contaminated soils and sediments, off-site
disposal, in situ treatment of contaminated ground water.
Alternative E: Excavation and off-site treatment and
disposal of contaminated soils and sediments.
Alternative El: Excavation and off-site treatment and
disposal of contaminated soils and sediments,
extraction and on-Site treatment of contaminated ground
water.
Alternative E2: Excavation and off-site treatment and
disposal of contaminated soils and sediments, in situ
biological treatment of contaminated ground water with
limited aboveground treatment.
Alternative F: In situ treatment of contaminated soils with
steam stripping and solidification, excavation and off-site
disposal of contaminated sediments.
Alternative Fl: In situ treatment of contaminated soils
with steam stripping and solidification, excavation and off-
site disposal of contaminated sediments,, extraction and on-
site treatment of contaminated ground water.
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Alternative F2: In situ treatment-of contaminated soils
with, steam stripping and solidification, excavation and off-
site disposal of contaminated sediments, in situ biological
.treatment of ground water with limited aboveground
treatment.
Alternative A: NO ACTION
Capital Cost:3 $ -0-
Annual O&M Cost: $ 66,100
Total Present Worth: $ 1,016,122
Implementation Time: 30 years
Section 300.430(e)(6) of the NC? requires that a "No Action"
alternative be evaluated, at every NPL site In order to establish
a baseline for comparison. Under this alternative, EPA would
take no further.remedial action at the Site to prevent exposure
to the contaminated media or to otherwise reduce risks at the
Site. Ground water and surface water would be monitored under
this alternative.
Alternative B: CAPPING OF CONTAMINATED SOIL AND SEDIMENT,
LIMITED INSTITUTIONAL CONTROLS
Capital Cost: $ 266,000-
Annual O&M Cost: $ 63,500
Total Present Worth: $ 1,049,000
Implementation Time: 30 years-
Alternative 3 would eliminate direct contact with the
contaminated soil and sediments through the installation of a
RCRA Subtitle C multilayer cap. The cap would also reduce
surface water infiltration through the contaminated soil and
reduce•the continued migration of contaminants to the ground
water. The capped area would be fenced to restrict access. Both
the cap and the fence would be maintained to ensure long-tern-,
protectiveness.
Prior to capping, this alternative would include the •
excavation of contaminated stream sediments and surface" soils
beyond the bermed disposal area. Additional sampling would be
performed during the Remedial Design to determine the exact
limits of excavation. The excavated material would be placed
within the bermed area within the area to be capped.
3The costs provided in this document are estimates to be
used solely for the purpose of comparative analysis.
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Deed restrictions would be placed on the contaminated
property to prohibit use-of the contaminated ground water and to
protect the integrity of the cap. Ground water monitoring would
be continued to detect any impact to local residents from the
migration of ground water contamination.
A periodic.review pursuant to CERCLA § I21(c), 42 U.S.C. §
9621(c), would be required under this alternative.
Alternative Bl: CAPPING OF CONTAMINATED SOILS AND SEDIMENTS,
EXTRACTION AND ON-SITE TREATMENT OF
CONTAMINATED GROUND WATER, LIMITED
INSTITUTIONAL CONTROLS
Capital Cost: $ 836,423
Annual.O&M Cost: $ 234,508
Total Present Worth: $ 4,491,273
Implementation Time: 30 years
All of the actions described under Alternative B would be
implemented. In addition, contaminated ground water would be
extracted and treated on-site to achieve the cleanup levels (see
Table 12). For costing purposes, it was assumed that three
extraction wells would be used. Additional field investigations
would be performed during the Remedial Design to determine the
appropriate configuration of the extraction well network and the
need for additional extraction wells. This alternative would
include the following elements in addition to those described fo:
Alternative B:
• Ground water extraction via pumping wells;
• Metals removal via precipitation and sedimentation;
• Organics destruction via UV oxidation;
• Carbon'polishing; and
• • Surface discharge of treated ground water to the
intermittent stream.
A monitoring program would be implemented to measure the
effectiveness of the ground water treatment system, to evaluate
potential impacts of the system on ecological receptors, and to
ensure local residents are not impacted by cleanup activities.
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Alternative B2: CAPPING OF CONTAMINATED SOILS AND SEDIMENTS,
IN SITU TREATMENT OF CONTAMINATED GROUND
WATER WITH LIMITED ABOVEGROUND TREATMENT,
. LIMITED INSTITUTIONAL CONTROLS
Capital Cost: $ 1,419,548
Annual O&M Cost: $ 376,500
Total Present Worth: $ 5,327,505
Implementation Time: 15 years
All of the requirements described under Alternative B would
be implemented. In addition, ground water treatment would be
implemented primarily by in situ biological treatment of phenols,
ketones., and aromatic hydrocarbons (and possibly some chlorinated
hydrocarbons), and aboveground treatment of metals, pesticides,
PCBs, and other non-biodegradable compounds. The treatment
system would extract ground water from the center of the plume of
contamination, treat it aboveground to remove non-biodegradable
compounds, add nutrients and oxygen needed to promote growth of
aerobic microorganisms, and reinject the water at the periphery
of the plume. This treatment system would be designed to destroy
the highest concentration contaminants in situ to reduce the time
required to reach the cleanup levels (see Table 12). The ground
water in the upper portions of the saprolite aquifer would be
treated through a conventual extraction and treatment process.
A monitoring program would be implemented to measure the
effectiveness of the ground water treatment system, to evaluate
potential impacts of the system on ecological receptors, and to
ensure local residents are not impacted by cleanup activities.
Alternative C: EXCAVATION OF SOILS AND SEDIMENTS, ON-SITE
THERMAL DESORPTION TREATMENT OF ORGANICS-
CONTAMINATED SOILS AND SEDIMENTS, ON-SITE
SOLVENT EXTRACTION TREATMENT OF METALS-
CONTAMINATED SOILS AND SEDIMENTS, ON-SITE
DISPOSAL
Capital Cost: $ 1,556,024
Annual O&M Cost: $ 63,500
Total Present North: $ 2,215,132
Implementation Time: 1 year
Alternative C provides for the excavation of contaminated
soils and stream sediments followed by on-site treatment and
backfilling at the Site. The organics would be treated by
thermal desorption, and the metals by solvent extraction. The
total estimated volume of contaminated soil to be treated is
5,269 yd3, based on concentrations exceeding the soil cleanup
levels to a depth of six feet. Additional sampling would be
performed during the Remedial Design to determine the exact
extent of soil and sediment excavation.
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Excavated soils and sediments would be-treated by thermal
desorption to remove organic contaminants above health-based
cleanup levels (see Table 12). The thermal desorption process
consists of heating solids containing organic contaminants,
thereby driving off the water and organic contaminants and
producing a dry solid containing trace amounts of the organic
residue. The treated soils and sediments would be backfilled on-
site.
Solvent extraction would then be utilized to remove metals
above health-based cleanup levels (see Table 12}. Solvent
extraction uses a treatment tank in which soil is homogeneously
mixed, flooded with a solvent, and again mixed thoroughly to
allow the waste to come in contact with the solution. Once
mixing is complete, the solvent is drawn off by gravity, vacuum
filtration, or some other conventional dewatering process. The
solids are then rinsed with a neutralizing agent (if needed) and
dried.
Treatability studies would be required to determine the
solvent with the best chemical characteristics needed to
adequately address the conditions at the Site. The solvent would
be treated for reuse on-site through neutralization. The
regeneration process' would generate a metals sludge which would
be disposed of off-site. It is expected that the sludge would be
handled as a hazardous waste requiring treatment at a RCRA-
permitted facility prior to disposal.
Deed restrictions would be placed on the contaminated
property to prohibit use of the contaminated ground water.
Ground water monitoring would be continued to detect any impact
to local residents from the migration of ground water
contamination. A periodic review pursuant to CERCLA § 121(c), 42
U.S.C. § 9621(c), would be required under this alternative.
ALTERNATIVE Cl: EXCAVATION OP CONTAMINATED SOILS AND
SEDIMENTS, ON-SITE THERMAL DESORPTION
TREATMENT OF ORGANICS-CONTAMINATED SOILS AND
SEDIMENTS, ON-SITE SOLVENT EXTRACTION
TREATMENT OF METALS-CONTAMINATED SOILS AND
SEDIMENTS, ON-SITE DISPOSAL, EXTRACTION AND
ON-SITE TREATMENT OF CONTAMINATED GROUND
WATER
#
Capital Cost: $ 5,155,532
Annual O&M Cost: $ 234,500
Total Present Worth: $ 8,760,382
Implementation Time: 30 years
All of the actions described under Alternative C would be
implemented. In addition, ground water would be treated as
described in Alternative Bl. Deed restrictions would be required
64
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until the cleanup standards have been achieved.
Alternative C2: EXCAVATION OF CONTAMINATED SOILS AND
SEDIMENTS, ON-SITE THERMAL DESORPTION
TREATMENT OF ORGANICS-CONTAMINATED SOILS AND
SEDIMENTS, ON-SITE SOLVENT EXTRACTION
TREATMENT OF METALS-CONTAMINATED SOILS AND
SEDIMENTS, ON-SITE DISPOSAL, IN SITU
TREATMENT OF GROUND WATER
Capital Cost: $ 5,708,657
Annual O&M Cost: $ 376,500
Total Present vJorth: $ 9,616,614
Implementation Time: 15 years
All of the actions described under Alternative C would be
implemented. In addition, ground water would be treated as
described in Alternative B2. Deed restrictions would be required
until the cleanup standards have been achieved.
Alternative D: EXCAVATION OF CONTAMINATED SOILS AND
SEDIMENTS, ON-SITE THERMAL DESORPTION
TREATMENT OF CONTAMINATED SOILS AND
SEDIMENTS, OFF-SITE DISPOSAL
Capital Cost: $ 3,233,075
Annual O&M Cost: $ 63,500
Total Present Worth: $ 3,892,183
•Implementation Time: 1 year
Alternative D is similar to Alternative C except that no
metals treatment would be provided on-site, and the excavated and
created soils and sediments would be disposed of off-site. The
objective of the on-site treatment is to reduce the total mass of
PCBs and other organic contaminants sent to the landfill for off-
site disposal. Treated soil would be disposed of in an off-site
RCRA Subtitle'D-permitted landfill, unless found to exhibit.
hazardous characteristics. Soils found to exhibit hazardous
characteristics would require treatment and disposal at a RCRA-
permitted Subtitle C facility.
Deed restrictions would be placed on the contaminated
property to prohibit future residential development and~/or use of
the contaminated ground water. Ground water monitoring would be
continued to detect any impact to local residents from the
migration of ground water contamination.
A periodic review pursuant co CERCLA § I2I(c), 42 U.S.C. §
9621 (c), would be required under this alternative.
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Alternative Dl: EXCAVATION OF CONTAMINATED SOILS AND
SEDIMENTS, ON-SITE THERMAL DESORPTION
TREATMENT OF CONTAMINATED SOILS AND
SEDIMENTS, OFF-SITE DISPOSAL, EXTRACTION AND
ON-SITE TREATMENT OF CONTAMINATED GROUND
WATER
Capital Cost: $ 4,155,775
Annual O&M Cost: $ 376,500
Total Present Worth: $ 8,063,732
Implementation Time: 15 years
All of the actions described under Alternative D would be
implemented. In addition, ground water would be treated as
described in Alternative Bl. Deed restrictions would be required
until the cleanup standards have been achieved.
Alternative D2: EXCAVATION OF CONTAMINATED SOILS AND
SEDIMENTS, ON-SITE THERMAL DESORPTION
TREATMENT OF CONTAMINATED SOILS AND
SEDIMENTS, OFF-SITE DISPOSAL, IN SITU
TREATMENT OF CONTAMINATED GROUND WATER
Capital Cost: $ 4,033,000
Annual O&M Cost: $ 376,500
Total Present Worth: $ 8,063,732
Implementation Time: 15 years
All of the actions described under Alternative D would be
implemented. In addition, ground water would be treated as
described in Alternative B2. Deed restrictions would be required
until the cleanup standards have been achieved.
Alternative E: EXCAVATION 21D OFF-SITE DISPOSAL OF
CONTAMINATE.;- SOILS. AND SEDIMENTS
Capital Cost: $ 524,157
Annual O&M Cost:- $ 63,500
Total Present Worth: $1,183,265
Implementation Time: 1 year
Under- Alternative E, contaminated soil and sediments
above cleanup levels described in Table 12 would be excavated,
treated if necessary, and disposed at an off-site landfill.
Additional sampling would be performed during the Remedial Design
to determine the exact extent of sediment excavation. Soils and
sediments found to be RCRA ncnr.azardous could be disposed of in
an off-site RCRA Subtitle D Idr.if ill. Soils and sediments found
to be RCRA hazardous would recr r« treatment and disposal at a
RCRA-permitted Subtitle C fac:» cy. Solely for cost estimation
purposes, 15% of the metals-cc. aminated soil is ass-, ^ed to
require disposal in a RCRA Su«;-. :,tle C facility.
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Soils found co contain ?C3s above 50 mg/kg (expected ro be a
very small quantity) would be disposed of at a Toxic Substances
Control Act (TSCA) landfill. Soils found to contain ?C3s less
than 50 mg/kg would be disposed of in accordance with Virginia
Solid Waste Management Regulations (VSWMR) § 672-20-10, if
disposed in Virginia. If soils are disposed in another state, .
they will be disposed in accordance with applicable state
requirements.
Deed restrictions would be placed on the contaminated
property to prohibit future use of the contaminated ground water.
Ground water monitoring would be continued to detect any impact
to local residents from the migration of ground water
contamination.
A periodic review pursuant to CERCLA § 121(c), 42 U.S.C. §.
9621(c), would be required under this alternative.
Alternative El: EXCAVATION AND OFF-SITE DISPOSAL OF
CONTAMINATED SOILS AND SEDIMENTS, EXTRACTION
AND ON-SITE TREATMENT OF CONTAMINATED GROUND
.WATER
Capital Cost: $ 2,341,432
Annual O&M Cost: $ 234,500
Total Present Worth: $ 5,946,282
Implementation Time: 30 years
All of the actions described under Alternative E would be
implemented. In addition, ground water would be treated and
monitored as described in Alternative Bl. Deed restrictions
would be required until the cleanup standards have been achieved.
Alternative E2: EXCAVATION AND OFF-SITE DISPOSAL OF
CONTAMINATED SOILS AND SEDIMENTS, IN SITU
TREATMENT OF CONTAMINATED GROUND WATER
Capital Cost: $ 2,927,557
Annual'O&AT Cost: $ 376,500
Total Present Worth: $ 6,835,514
Implementation Time: 15 years
All of the actions described under Alternative E would be
implemented. In addition, ground water would be treated as
described in Alternative B2. Deed restrictions would be required
until the cleanup standards have been achieved.
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Alternative F: IN SITU TREATMENT OF CONTAMINATED SOILS WITH
STEAM STRIPPING AND SOLIDIFICATION,
EXCAVATION AND OFF-SITE DISPOSAL OF
CONTAMINATED SEDIMENTS
Capital Cost: $ 4,011,75.7
Annual O&M Cost: $ 63,500
Total Present Worth: $ 4,670,865
Implementation Time: 1 year
This alternative treats soils via in situ techniques. In
situ steam stripping would force steam into areas of organic
contamination to volatilize the contaminants. The area being
treated would be enclosed to capture the volatilized
contaminants. In situ solidification would be used to immobilize
metals found in contaminated soil. Large bore augers are used to
penetrate and mix the soil. Solidification agents such as
Portland cement, silicates, or other proprietary additives are
introduced through the auger to the soil.
Sediments, because they are located near the surface, are
not good candidates for the in situ technologies identified for
this Site's contaminants. Therefore, contaminated sediments
would be excavated and disposed of off-site. Additional sampling
would be performed during the Remedial Design to determine the
exact extent of sediment excavation. For costing purposes, it is
assumed that the excavated sediments do not exhibit RCRA
hazardous wastes characteristics. Under these circumstances,
treatment would not be required and the excavated sediments would.
be disposed of off-site in a RCRA'Subtitle D-permitted landfill.
Additional sampling of the sediments would be performed during
the Remedial Design to determine the need for treatment.
Deed restrictions would be placed on the contaminated
property to prohibit future use of the contaminated ground water.
Ground water monitoring would be continued to detect any impact
to local residents from the migration of ground water
contamination.
A periodic.review pursuant to CERCLA § 121(c), 42 U.S.C. §
9621(c), would be required under this alternative.
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Alternative Fl:
Capital Cost:
Annual O&M Cost:
Total Present Worth:
Implementation Time:
IN SITU TREATMENT OF CONTAMINATED SOILS WITH
STEAM STRIPPING AND SOLIDIFICATION,
EXCAVATION AND OFF-SITE DISPOSAL OF
CONTAMINATED SEDIMENTS, EXTRACTION AND ON-
SITE TREATMENT OF CONTAMINATED GROUND WATER
$ 4,632,007
$ 234,500
$ 8,236,857
30 years
All of the actions described under Alternative F would be
implemented. In addition, ground water would be treated as
described in Alternative Bl. Deed restrictions would be required
until the cleanup standards have been achieved.
Alternative F2:
Capital Cost:
Annual O&M Cost:
Total Present Worth:
Implementation Time:
IN SITU TREATMENT OF CONTAMINATED SOILS WITH
STEAM STRIPPING AND SOLIDIFICATION,
EXCAVATION AND OFF-SITE DISPOSAL OF
CONTAMINATED SEDIMENTS, IN SITU BIOLOGICAL
TREATMENT OF GROUNDWATER WITH LIMITED ABOVE-
GROUND TREATMENT
$ 5,165,132
$ 376,500
$ 9,073,089
15 years
All of the actions described under Alternative F would be
implemented. In addition, ground water would be treated as
described in Alternative B2. Deed restrictions would be required
until the cleanup standards have been achieved.
IX.
COMPARISON OF ALTERNATIVES
The remedial action alternatives described above were
evaluated using the following criteria, as required under the
NCP, 40 C.F.R. 300.430(e)(9)(iii):
Threshold Criteria: Statutory requirements that each alternative
must satisfy in order to be eligible for selection
1) Overall Protection of Human Health and the Environment.
Evaluation of the ability of each alternative to provide
adequate protection of human health and the environment in
the long and short-term; description of how risks posed
through each exposure pathway are eliminated, reduced, or
controlled through treatment, engineering controls, or
institutional controls.
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2) Compliance with Applicable or Relev~ and Appropriate
Requirements (ARARs).
Evaluation of the ability of each al~-rnative to attain
applicable or relevant and appropriata requirements under
federal environmental laws and state environmental or
facility siting laws or provide grounds for invoking a
waiver established under CERCLA.
Primary Balancing Criteria: Technical criteria upon which the
detailed analysis is primarily based.
3) Long-Term Effectiveness and Permanence
Evaluation of expected residual risk and the ability of each
alternative to maintain reliable protection of human healch
and the environment over time after cleanup requirements
have been met.
4) Reduction of Toxicity, Mobility, or Volume through Treatment
Evaluation of the degree to which an alternative employs
treatment methods to reduce the toxicity, mobility, or
volume of hazardous substances at the Site.
5") Short-Term Effectiveness
Evaluation of the period of time needed to achieve
protection and any adverse impacts on human health and the
environment that may be posed during the construction and
implementation period.
6) Implementability
Evaluation of the technical and administrative feasibility
of each alternative, including the availability of materials
and services.
7)- Cost
Section 121 of CERCLA, 42 U.S.C. § 9621, requires selection
of a cost-effective remedy that protects human health and
the environment and meets the other requirements uf the
statute. Alternatives are compared using present worth
cost, which includes all capital costs and the operation and
maintenance cost incurred over the life of the project.
Capital costs include expenditures necessary to implement a
remedial action (e.g.., construction costs) . All costs
presented are estimates computed for comparison purposes
only.
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Modifying Criteria: Criteria considered throughout: the
development of the preferred remedial alternative and formally
assessed after the public comment period, which may modify the
preferred alternative.
8) State Acceptance
Assessment of technical and administrative issues and
concerns that the State may have regarding each alternative.
9) Community Acceptance
Assessment of issues and concerns the public may have
regarding each alternative based on a review of public
comments received on the Administrative Record and the
Proposed Plan.
A. Overall Protection of Human Health and the Environment
Alternatives that do not include remediation of the ground
water contamination at the Site do not address potential human
health risks posed by use of ground water. Alternatives A, B, C,
D, E, and F, therefore, do not meet this threshold criteria for."
overall protection of human health and the environment and will
not be considered further in this analysis.
Alternatives Bl and B2 reduce risks posed via"'Site soils,
sediments, surface water, and ground water by capping the
.contaminated soils and sediments in the disposal area
(contaminated sediments will be removed and consolidated into the
disposal area prior to capping) and extracting and treating the
ground water. Reduced risk will be achieved only if the cap is
properly maintained and the extraction system continues to
operate.
Alternatives Cl, C2, Dl, D2, El, E2, Fl, and F2 all
effectively reduce risks posed by Site contaminants through
treatment and/or disposal of soils and sediments and treatment of
contaminated ground water. Alternatives Cl and C2 treat the
soils and sediments to health-based cleanup levels (see Table
1:2) . Alternatives Dl and D2 treat organic contaminants on-site,
then dispose of the treated soils and sediment in an off-site
landfill. Alternatives Fl and F2 treat soils on-site to health-
based cleanup levels and dispose of sediments in an off-site'
landfill. Alternatives El and E2 dispose of soils and sediments
in an off-site landfill.
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B. Compliance with Applicable or Relevant and Appropriate
Requirements (ARARs.) and To Be Considered Materials (TBCs)
Under Section 121(d) of CERCLA, 42 U.S.C. § 9621(d), and EPA
guidance, remedial actions at Superfund sites must attain legally
applicable or relevant and appropriate Federal and state
environmental standards, requirements, criteria, and limitations
(collectively referred to as ARARs). Applicable requirements are
those substantive environmental protection requirements,
criteria, or limitations promulgated under Federal or state law
that specifically address hazardous substances found at the Site,
the remedial action to be implemented at the Site, the location
of the Site, or other circumstances at the Site. Relevant and
appropriate requirements are those which, while not applicable to
the Site, nevertheless address problems or situations
sufficiently similar to those encountered at the Site that their
use is well suited to that Site.
An overview of site-specific ARARs is presented below in
Table 10.
1. CHEMICAL-SPECIFIC ARARs
Chemical-specific soil ARARs exist only for PCB
contamination (see Table 10) . The PCB ARAR would not be met with
Alternatives Bl or B2. Alternatives Cl, C2, Dl, D2, El, E2, Fl,
and F2 will meet the soil ARARs through soil excavation and/or
treatment.
Chemical-specific ARARs for ground water exist as federal
drinking water standards and state ground water quality
standards. Alternatives Bl, B2, Cl, C2, Dl, D2, El, E2, Fl, and
F2 would meet the ground water ARARs through attraction and
treatment or in situ treatment throughout the :,aprolite aquifer.
Long extraction and treatment durations may be required before •
ARARs are achieved.
2. ACTION-SPECIFIC ARARs
Action-specific ARARs are applicable on an alternative-
specific basis. All alternatives discharging treated ground
water (Alternatives Bl, Cl, Dl, El, and Fl) would meet the
substantive state and federal discharge requirements.'-
Alternatives reinjecting ground water as part of an in situ
treatment program (Alternatives B2, C2, D2, E2, and F2) would
meet the requirements of the VDEQ for ground water injection.
Alternatives Bl and B2 would meet action-specific ARARs for
cap construction. Soil•treated by thermal desorption under
Alternatives Cl, C2, Dl, and D2 or by in situ steam stripping
under Alternatives Fl and F2 would meet air emission criteria. If
total PCB concentrations greater than 50 mg/kg are treated by
72
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TABLE 10
Applicable or Relevant and Appropria
and Other Standards To Be C
Standards, Requirements,
Criteria, or Limitations
Citation
te Requirements (ARARs)
kmsidered (TBC)
Description
CHEMICAL-SPECIFIC ARARs and TBCs
Safe Drinking Water Act
Regulations
Toxic Substances Control
Act Regulations
Revised Interim Soil Lead
Guidance for CERCLA
Sites and RCRA
Corrective Action Facilities
Guidance on Remedial
Actions for Superfund
Sites with PCB
Contamination
The Potential for
Biological Effects of
Sediment-Desorbed
Contaminants Tested in
the National Status and
Trends Program
40C.F.R. Part 141,
SubpartF
40 C.F.R. Part 141,
Subpart B
40 C.F.R. §761,
Subpart G
OSWER Directive No.
9355.4-1 2, July 1994
OSWER Directive No.
9355.4-01, August
1990
NOAA Technical
Memorandum NOS
OMA52, March 1990
Establishes Maximum Contaminant
Levels (MCLs) and non-zero Maximum
Contaminant Level Goals (MCLGs) that
would be allowed to remain in ground
water used for drinking water
Establishes level for PCB cleanups and
remediation requirements
Establishes a process and factors to
determine Site-specific lead cleanup
levels that are protective of human
health (TBC)
Establishes level of PCB cleanup and
remediation requirements
(TBC)
Established chemical-specific goals for
sediment remediation
(TBC)
ACTION-SPECIFIC ARARs and TBCs
Resource Conservation
and Recovery Act (RCRA)
Regulations and Virginia
Hazardous Waste
Management Regulations
(VHWMR)
40 C.F.R. Part 261
VHWMR Part III
40 C.F.R Part 262
VHWMR Part VI
40 C.F.R. Part 263
VHWMR Part VII
40 C.F.R. Part 264
VHWMR Part X
40 C.F.R. Part 268
VHWMR Part XV
Identification and listing of hazardous
waste
Standards applicable to generators of
hazardous waste
Standards applicable to transporters of
hazardous waste
Standards for owners and operators of
hazardous waste treatment, storage
and disposal facilities
Land Disposal Restrictions
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Virginia Solid Waste
Management Regulations
(VSWMR)
Clean Water Act (CWA)
Regulations
Virginia State Water
Control Board
Regulations
Virginia Pollution
Discharge Elimination
System Regulations
Virginia Pollution
Abatement Permit
Program Regulations
Clean Air Act Regulations
Virginia Water Protection
Permit Regulations
Virginia Air Pollution
Control and Abatement
Regulations
Virginia Erosion and
Sediment Control
Regulations
Endangered Species Act;
Virginia Endangered
Species Act
VR 672-20-10
40 C.F.R. § 122.44
VR 680-21 -00
VR 680-14-00
VR 680-14-00
40 C.F.R. Part 50
40 C.F.R. Part 50
VR 680-1 5-01
VR 120-01 •
VR-625-02-00
16U.S.C. 1531 ft sea
Code of Virginia §§
29.1 to 100 et sea
Requirements for the identification,
treatment, storage and disposal of solid
wastes
Ambient Water Quality Standards
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thermal desorption, the system would provide treatment equivalent
to that required by a TSCA-permitted incinerator.
Alternatives Dl, D2, El, E2, Fl, and F2 would meet action-
specific ARARs for excavation, staging, transportation, and off-
site disposal at a RCRA-pertnitted landfill.
3. LOCATION-SPECIFIC ARARs
Location-specific ARARs for the Site are limited to
requirements to maintain the integrity of the wetlands
surrounding the Site during remediation.
Alternatives Bl, B2, Cl, C2, Dl, D2, El, E2, Fl, and F2
would impact wetlands to a similar degree, principally through
excavation of contaminated sediments. Alternatives involving
extraction, treatment, and discharge of ground water
(Alternatives Bl, Cl, Dl, El, and Fl) could potentially lower the
water table beneath the wetlands and partially dehydrate them.
This impact could potentially be minimized by discharging the
treated ground water directly to the wetlands.
C. Long-Term Effectiveness and Permanence
Alternatives Bl and B2 rely on continued maintenance of the
cap and the continued implementation of ground water treatment to
provide long-term effectiveness. These alternatives are
considered less effective over the long term than alternatives
that remove contaminants from the Site through treatment or off-
site disposal.
Alternatives Cl, C2, Dl, D2, El, and E2 provide a
significant level of long-term effectiveness through treatment of
contaminated soils, sediments, and ground water. Alternatives F.I
and F2 provide a similar level of long-term effectiveness through
treatment of contaminated soils and ground water. Under
Alternatives Fl and F2, sediments are also removed from the Site
and disposed' in an off-site landfill.
Alternatives El and E2 provide for long-term effectiveness
by excavation and off-site disposal of contaminated soils and
sediments in a RCRA-permitted landfill and through treatment of
the ground water.
D. Reduction of Toxicity, Mobility, or Volume Through Treatment.
The cap component of Alternatives Bl and B2 do not involve
treatment of soils and sediments and will not reduce the toxicity
or volume of contamination in these media. The cap may, however,
serve to reduce the mobility of- soil and sediment contaminants by
reducing erosion and downward percolation of water. The ground
water treatment components of these alternatives will, however,
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effectively reduce the toxicity, mobility, and volume of
contaminants in ground water.
Alternatives Cl and C2 provide the highest reduction of
toxicity, mobility, and volume through treatment. All media
would be treated on-site to remove Site contaminants.
Concentrated waste generated by the on-site treatment processes
would then be taken off-site for further treatment and/or
disposal.
Alternatives Dl, D2, Fl, and F2 also achieve significant
reductions-of toxicity, mobility, or volume through treatment.
Under Alternatives Dl and D2, Site contaminants (with the
exception of metals in soil) are removed from all media through
treatment. Soils with metals contamination are disposed off-site
(soils determined to be RCRA characteristic waste would be
treated prior to disposal to meet Land Disposal Restrictions).
Under Alternatives Fl and F2, Site contaminants are removed from
soils and ground water. Sediments are disposed off-site. As
with Alternatives Cl and C2, concentrated wastes generated by
removing Site contaminants through on-site treatment processes
would require further treatment and/or disposal off-site.
Alternatives El and E2 reduce the toxicity, mobility, and
volume of Site contaminants via excavation of soils and sediments
and ground water treatment.
E. Short-Term Effectiveness
Alternatives Bl, B2, Cl, C2, Dl, D2, El, E2, Fl, and F2
would cause a temporary increase in the amount of dust produced,
noise disturbance, and truck traffic. Alternatives Dl, D2, El,
E2, Fl, and F2 would produce greater amounts of truck traffic due
to the increased use of off-site disposal. Alternatives Cl, C2,
Dl, and D2 utilize on-site thermal desorption. Although this
process produces an offgas, pollution control equipment would
eliminate potential threats to nearby residents during operation.
In situ steam stripping (Alternatives Fl and F2) also generates
an offgas that would require treatment.
Alternatives Bl and B2 would require the least amount of
time to implement. Alternatives El and E2 could be implemented
faster than Alternatives Cl, C2, Dl, D2, Fl, and F2, as no
thermal desorption or in situ treatment would be carried out on-
site. Groundwater treatment for Alternatives Bl, B2, Cl, C2, Dl,
D2, El, E2, Fl, and F2 would continue for many years, although
the treatment duration for Alternatives Bl and B2 will likely be
longer since the source of contamination will not be removed.
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F. Implementability
The cap required in Alternatives Bl and B2 can be readily
implemented. Most soil and groundwater treatment processes for
Alternatives Bl, B2, Cl, C2, Dl, D2, El, E2, Fl, and F2 could be
readily implemented as well. As Alternatives Fl and F2 treat the
soil in situ, it may be difficult to ensure that all contaminated
soil is treated. The in situ groundwater treatment component of
Alternatives B2, C2, D2, E2, and F2 may be difficult to implement
if Site conditions prove unsuitable for promoting subsurface
bacterial growth, or if other problems arise, such as
difficulties in re'injecting treated water and/or providing
sufficient oxygen to the groundwater plume. Treatability studies
would be required during the remedial design to determine the
implementability of the in situ ground water treatment component.
G. Cost Effectiveness
The costs of the alternatives increase from containment (Bl
and B2), to primary off-site disposal (El and E2) , to in. situ
treatment alternatives (Fl and F2), to the alternatives employing
excavation and soil treatment (Cl, C2, Dl, and D2). In situ . .
treatment is estimated to be slightly less costly than
aboveground treatment. The low volatility of PCBs means that
longer steam-stripping durations would be required. This
increases the cost of this treatment and reduces the savings that
can be realized through in situ treatment.
Table 11 is a summary of costs for all alternatives. The
cost estimates presented here are much lower than those found in
the Revised Proposed Remedial Action Plan because we are no
longer considering the Site wastes to be listed RCRA wastes.
Therefore, disposal costs are expected to be lower.
Table 11 - Cost Summary of Remedial Alternatives
ALTERNATIVE
Bl
B2
Cl
C2
Dl
D2
El
CAPITAL COST
$886,423
$1,419,548
$5,155,532
$5,708,657
$3,729,275
$4,155,775
$2,341,432
PRESENT WORTH
0 & M
$3,604,850
$3,907,957
$3,604,850
$3,907,957
$3,604,850
$3,907,95.7
$3,604,850
TOTAL COST
$4,491,273
$5,32J,505
$8,760,382
$9,616,614
$7,334,125
$8,063,732
$5,946,282
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E2
Fl
F2
$2, 927-, 557
$4,632,007
$5,165,132
$3,907,957
$3,604,850
$3,907,957
$6,835,514
$8,236,857
$9,073,08
H. State Acceptance
i
VDEQ has had the opportunity to review and comment on all
the documents in the Administrative Record and has participated
in selecting the remedy for this Site. VDEQ has had the
opportunity to comment on the draft ROD and, to the extent
possible, the Commonwealth's comments have been incorporated into
the ROD. The commonwealth has not concurred with this ROD.
I. Community Acceptance
The community has been in general agreement with the
alternative selected in this Record of Decision. Companies that
are associated with the Site have, however, voiced opposition to
some components of the chosen alternative. Oral and written
comments on the remedial alternatives evaluated by EPA for
implementation at the Site are included in Part III of this ROD.
X. SELECTED REMEDY AND PERFORMANCE STANDARDS
Based upon consideration of the requirements of CERCLA, the
detailed analysis of the alternatives presented in the initial
Proposed Remedial Action Plan and the Revised Proposed Plan using
the nine criteria, and public comments, EPA has determined that
Alternative El is the most appropriate remedy for the HH Burn Pit
Superfund Site. The major components of the remedy and the
required performance standards are listed below.
A. Soil/Sediment Excavation Performance standards
1. All soils in the unsaturated zone above the water table that
exceed the soil cleanup levels in Table 12 shall be
excavated. To the extent practicable, excavation shall be
performed when the water table is at the seasonally low
elevation. The volume of soil to be excavated is estimated
to be 5,400 yd3 based on existing information. The full
extent of excavation shall be determined during the remedial
design.
2. Sediments in the drainage system downgradient of the bermed
disposal area, including but not limited to the intermittent
stream and the Black Haw Branch, that exceed the sediment
cleanup levels in Table 12 shall be excavated. The volume
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Table 12 - Performance Standard Cleanup Levels
Media
SOIL:
SEDIMENT:
GROUND WATER:
Hazardous Substance
PCBs
Lead
PCBs
Copper
Lead
Zinc
PCBs
Benzene
Bis(2-chloroethyl)ether
1 ,2-dichloroethane
1,1-dichloroethene
Vinyl chloride
2-butanone
Cleanup
Level
1 mg/kg
400 mg/kg
1 mg/kg
34 mg/kg
200 mg/kg
150 mg/kg
0.02 ug/L*
0.06 ug/L5
0.06 ug/L6
0.01 ug/L9
0.01 ug/L6
0.03 ug/L6
4,693 ug/L
4 The lowest level at which the entire analytical system gives a recognizable signal and acceptable
calibration point using Method 608, 40 C.F.R. Part 136, Appendix A.
5 The lowest level at which the entire analytical system gives a recognizable signal and acceptable
calibration point using Method 503.1, Manual for the Certification of Laboratories Analyzing Drinking
Water. September 1992, EPA-814B-92-002.
6 The lowest level at which the entire analytical system gives a recognizable signal and acceptable
calibration point using Method 502.1, Manual for Certification of Laboratories Analyzing Drinking Water.
September 1992, EPA-814B-92-002.
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of sediment to be excavated is estimated to be 600 yd3 based
on existing information. Additional sediment sampling and
analysis shall be performed during the Remedial Design to
determine the full extent of excavation.
3 . A survey shall be performed to determine if any species
protected by the Endangered Species Act (16 U.S.C. § 1531 et
seq.) are present in the Black Haw Branch and other
potentially affected waterways.
4. Excavation activities shall be conducted in manner that
minimizes damage to the tributary ecosystem and surrounding
wetlands. To the extent practicable, wildlife present in
the areas to be excavated shall be moved to comparable
natural areas prior to commencement of excavation
activities. Any impacts to wetlands shall be mitigated.
5. Air monitoring for dust and Site contaminants shall be
performed in accordance with 40 C.F.R. Part 50, to ensure
any air emissions conform with the National Primary and
Secondary Ambient Air Quality Standards. Fugitive dust
emissions shall also be controlled in accordance with
Virginia Air Pollution Control Board Regulations, VR § 120-
01.
6. Erosion and sediment control measures shall be installed and
maintained in accordance with the substantive requirements
of the Virginia Erosion and Sediment Control Law, Code of
Virginia §§ 10.1-560 et seq.. the Virginia Erosion and
Sediment Regulations, VR § 625-02-00. An erosion and
sediment control plan shall be prepared and submitted to EPA
for review.
7. All equipment used during excavation of contaminated soil
shall be decontaminated before entering uncontaminated
areas. The design and specifications for the
decontamination facilities shall be approved by EPA as part
of the remedial design. Any discharge of water generated
from Site decontamination activities shall be in compliance
with Virginia State Water Control Law, Code of Virginia §§
62.1-44.2 et seq., and Virginia State Water Control Board
Regulations (VR 680-21-00) .
8. Excavated areas in the bermed disposal area shall be
backfilled with clean fill and revegetated with native
species.
9. Additional sampling and analysis of soil shall be performed
prior to excavation to determine the full extent of
contamination. Sampling and analysis shall also be
performed after excavation has been completed to confirm
that cleanup levels set forth in the performance standards
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have been achieved. Methods for determining that the
cleanup levels have been reached shall be finalized during
remedial design and approved by EPA based on EPA 230/02-89-
042, Methods for Evaluating the Attainment of Cleanup
Standards. Vol I.
10. Excavated soil and sediment shall be temporarily staged on-
site in accordance with 40 C.F.R. Part 264, Subpart L and
VHWMR § 10.11, Waste Piles, if material can be staged in an
area of existing contamination. If soil and sediment will
be staged in a clean area, the waste material and soil shall
be temporarily staged in containers in accordance with RCRA
regulations contained in 40 C.F.R. Part 268, Subpart E;
containers shall be in compliance with 40 C.F.R. Part 264,
Subpart I and VHWMR § 10.8, Use and Management of
Containers.
B. Soil/Sediment Treatment and Disposal Performance Standards
1. Excavated soil and sediments shall be tested to determine if
the soil and/or sediments are hazardous, pursuaant to 40
C.F.R. Part 261, Subpart C; contaminated soil and sediments
that are not hazardous and do not exceed 50 mg/kg PCBs shall
be disposed of off-site at a permitted RCRA Subtitle D
landfill.
2. Soil and sediments that are hazardous, but do not exceed 50
mg/kg PCBs, shall be treated and disposed of off-site at a
permitted RCRA Subtitle C facility.
3. Soil and sediments that exceed 50 mg/kg PCBs shall be
disposed off-site in TSCA landfill in accordance with 40
C.F.R. § 761.60.
4. Transportation of hazardous waste from the Site shall be
performed in accordance with VHWMR Part VII,
Regulations applicable to Transporters of Hazardous
Waste and RCRA requirements, set forth in 40 C.F.R.
Parts 262 and 263, and 49 C.F.R. Parts 107 and 171-179.
5. Wastes shall be disposed of in accordance with the all
applicable statutes and regulations including, but_not
limited to, regulations governing off-site disposal found at
40 C.F.R. § 300.440.
C. Ground Water Treatment System Performance Standards
1. Ground water that exceeds the ground water cleanup levels in
Table 12 shall be extracted by a network of wells located to
intercept contaminated ground water at the Site. If
contaminants other than those listed for ground water in
Table 12 are detected, the cumulative carcinogenic and
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noncarcinogenic risks shall be calculated for all
contaminants using 'the assumptions found in Appendix B. If
the cumulative carcinogenic risk exceeds 10~4 or the
cumulative noncarcinogenic hazard index is greater than one
(1) , ground water extraction shall be continued until
acceptable cleanup levels are met (i.e., the cumulative
carcinogenic risk is less than 1Q~4 or the noncarcinogenic
hazard index is less than 1).
2. A network of ground water monitoring wells shall be
established to verify the performance of the ground water
treatment system. The wells shall be located and
constructed in a manner that permits accurate
characterization and monitoring of ground water throughout
the contaminated area.
3. The monitoring wells shall be sampled quarterly during the
first three years of operation of the ground water treatment
system and semi-annually thereafter until the ground water
cleanup requirements have been met throughout the
contaminated area. When ground water cleanup criteria
established in Section X.C.I, are achieved in samples
collected for twelve consecutive quarters, operation of the
ground water treatment system may cease. Semi-annual
monitoring of the ground water shall continue for five years
thereafter. If cleanup requirements are exceeded during
monitoring performed after operation of the treatment system
has ceased, operation shall be resumed until the above
requirements are again met.
4. Ground water shall be treated in an on-site facility
sufficient to achieve the criteria in Section X.C.5., below.
Specifically, such ground water shall be treated to ensure
removal of metals via precipitation and sedimentation,
destruction of organic contaminants via UV oxidation, and
carbon polishing as a final step.
An air sparging and soil vapor extraction system may be used
to accelerate removal of contamination from the ground water
and the saturated soils if a treatability study performed
during the Remedial Design successfully demonstrates that:
a. A sufficient quantity of air can be injected into the
saturated soil and ground water to strip contaminants
from the soil and/or water;
b. Contaminants stripped from the saturated soil and
ground water can be captured through the soil vapor and
ground water extraction and treatment systems and will
not be released to the ambient air; and
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c. Operation of the air sparging and soil vapor extraction
system will not cause further migration of ground water
contamination nor interfere with the other components
of the selected remedy.
Air sparging and soil vapor extraction technologies were
raised by several companies associated with the Site who
wished to substitute these technologies for the ground water
extraction system included in the Agency's preferred
remedial alternative for the Site. While EPA recognizes
that these technologies may accelerate the removal of
certain contaminants in conjunction with the ground water
extraction system, EPA is not requiring use of air sparging
or soil vapor extraction as part of this remedial action.
5. Treated ground water shall be discharged to the drainage
system downgradient of the bermed disposal area, or as
provided in Section X.C.7. below. The discharge shall meet
the effluent limits and flow rates established by the VDEQ
Water Division in accordance with Virginia State Water
Control Law, Code of Virginia §§ 62.1-44.2 et seq.. and
Virginia Pollution Discharge Elimination System Regulations
(VR 680-14-00).
6. Chemical and biological monitoring shall be performed to
evaluate the performance of the ground water treatment
system and detect any impacts to the tributary, surrounding
wetlands, and the nearest residences downgradient of the
Site. The monitoring requirements shall be developed during
the remedial design in accordance with Virginia State Water
Control Law, Code of Virginia §§ 62.1-44.2 et seq.. and
Virginia Pollution Discharge Elimination System Regulations
(VR 680-14-00) and shall be approved by EPA.
7. Operation of the extraction and treatment system shall not
dehydrate the wetlands. In the event that any dehydration
is observed, treated ground water may be diverted to the
wetlands to minimize impact to the wetlands.
8. Sludges and other metal-containing waste generated by the
ground water treatment process shall be tested using TCLP to
determine if they exhibit characteristics of hazardous
waste, pursuant to 40 C.F.R. Part 261, Subpart C; sludges
that do not exhibit hazardous characteristics during testing
shall be disposed of off-site at a permitted RCRA Subtitle D
landfill; sludges that exhibit hazardous characteristics
shall be treated and disposed of off-site at a permitted
RCRA Subtitle C facility; sludges stored on-site prior to
treatment and disposal shall be stored in compliance with
the Virginia Hazardous Waste Management Regulations (VHWMR)
§ 10.8, Use and Management of Containers, or § 10.9, Tanks;
transportation of sludges shall be in compliance with VHWMR
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Part VII, Regulations Applicable to Transporters of
Hazardous Waste and 49 C.F.R. Parts 107 and 171-179,
regulating transportation of hazardous wastes. Carbon
filters shall be disposed or regenerated offsite in
accordance with applicable requirements and to ensure that
Site contaminants are not transferred to other environmental
media. Waste disposal shall comply with regulations found
at 40 C.F.R. § 300.440.
9. Any air emissions from any onsite treatment system shall
comply with Virginia Air Pollution Control Law, Code of
Virginia §§ 10.1-1300 et. seq.; the Virginia Department of
Air Pollution Control Regulations for the Control and
Abatement of Air Pollution (VR 120-01-01); and the federal
Clean Air Act, 42 U.S.C. § 7401 et sea.; and 40 C.F.R. Part
50.
XI. STATUTORY DETERMINATIONS
This remedy satisfies the remedy selection requirements of
CERCLA and the NCP. The remedy is expected to be protective of
human health and the environment, complies with ARARS, is cost-
effective, and utilizes permanent solutions and alternative
treatment technologies to the maximum extent practicable.
Because contaminated materials will be transported offsite for
landfilling at permitted facilities, the remedy does not meet the
statutory preference for treatment as a principal element of the
remedy for soils and sediments. The following is a discussion of
how the selected remedial action addresses these statutory
requirements:
A. Overall Protection of Human Health and the Environment
The selected remedy will provide adequate protection of
human health and the environment through the removal of soil and
sediments contaminated with metals, PCBs, and organics and the
extraction and treatment of metals- and organics-contaminated
ground water. These actions will reduce the carcinogenic risk to
within the acceptable EPA risk range of 10~4 to io~6 and achieve
a Hazard Index of less than one for non-carcinogenic risks.
There should be no unacceptable short-term risks .or cross-
media impacts posed by implementation of the selected remedial
alternative.
B. Compliance with Applicable or Relevant and Appropriate
Requirements (ARARs)
The selected remedy shall attain all action-, location-, and
chemical-specific applicable or relevant and appropriate
requirements for the Site.
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C. Cost Effectiveness
EPA has determined that the selected remedy most effectively
addresses all contaminated matrices while minimizing costs. The
estimated present worth cost of the selected remedy is
$5,946,282. Other alternatives were either less expensive but
less effective, or more expensive, but unable to offer a greater
degree of protection.
0. utilization of Permanent solutions and Alternative Treatment
(or Resource Recovery) Technologies to the Maximum Extent
Practicable
EPA has determined that the selected remedy represents the
maximum extent to which permanent solutions and treatment
technologies can be utilized in a cost-effective manner at the
Site. The ground water treatment system will achieve a permanent
reduction of Site risks associated with ground water because the
UV oxidation process will destroy the organic contaminants. To
address Site soils and sediments through alternative treatment
technologies, several technologies would be required to address
the various types of contamination present (i.e., metals, VOCs,
semi-volatiles). Several alternatives were evaluated that
treated soils and sediments; however, these^ technologies would
not achieve greater overall remedial protection for the added
costs.
E. Preference for Treatment as a Principal Element
The selected remedy utilized treatment as a principal
element for ground water remediation. Site soils and sediments
will be treated to the extent such action is necessary to meet
RCRA Land Disposal Restrictions and requirements governing
disposal of PCB-contaminated wastes. This methodology yields a
more cost effective approach to the remediation of soils and
sediments, since the combination of treatment technologies needed
to address contamination in these matrices would not (as
previously noted) achieve greater overall remedial protection for
the added costs.
XII. DOCUMENTATION OF SIGNIFICANT CHANGES
Four significant changes from the Revised Proposed Remedial
Action Plan appear in this Record of Decision. These changes
relate to the extent of soils excavation, the required cleanup
levels, the potential use of air sparging and soil vapor
extraction, and the issue of RCRA listed hazardous wastes at the
Site.
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A. Soils Excavation
Alternative El in the Revised Proposed Remedial Action Plan
required excavation of contaminated soils that exceeded cleanup
levels. A limit on the depth of soils excavation was not stated.
However, the volume of contaminated soil above the depth of six
feet was used in estimating the cost of excavation for this
alternative. The depth of six feet is the practical limit of
excavation due to the presence of the water table. The Record of
-Decision clarifies the limit on the depth of excavation by
explicitly stating that unsaturated soils above the water table
that exceed the cleanup level shall be excavated.
B. Cleanup Levels
Table 2 of the Revised Proposed Remedial Action Plan
presented proposed cleanup levels for ground water, soil, stream
sediments, and surface water. Table 12 of the ROD establishes
the final cleanup levels for ground water, soil, and sediments.
Cleanup levels for surface water are not required since action to
directly remediate surface water is not part of the selected
remedy. Surface water quality is expected to attain acceptable
levels following remediation of the contaminated sediments. The
soil cleanup level did not change. Changes did occur, however,
in the ground water and, to a lesser degree, the sediment cleanup
levels.
The Revised Proposed Remedial Action Plan identified the
Safe Drinking Water Act MCLs as the cleanup levels to be achieved
for the contaminants posing carcinogenic risk. Further review
of these levels indicates that the MCLs do not provide a
sufficient level of protection. The cumulative carcinogenic risk
associated with the MCLs for these contaminants exceeds 10~4.
When this occurs, Section 300.430(e)(2)(i)(D) of the NCP allows
consideration of health-based criteria when determining cleanup
levels to be attained. For known or suspected carcinogens,
acceptable exposure levels are generally concentration levels
that represent an excess upper bound lifetime cancer risk to an
individual of between 10~4 and 10"6 using information on the
relationship between dose and response. The 10~6 risk level
shall be used, in accordance with Section 300.430(e)(2)(i)(A) of
the NCP, as the point of departure for determining remediation
requirements for alternatives when ARARs are not available or are
not sufficiently protective because of the presence of multiple
contaminants at a site or multiple pathways of exposure.
EPA calculated the ground water cleanup levels that would
need to be attained for each of the seven contaminants to reduce
the total carcinogenic risk to 10~6 for individuals exposed to
ground water under the residential use scenario. These cleanup
values were all below levels that can be reliably quantified
using available analytical methods. Therefore, EPA has
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established the minimum level for. accurate analysis of
contaminants as the cleanup levels in the ground water. These
levels are presented in Table 12 of the ROD. EPA has calculated
the total carcinogenic risk associated with these cleanup levels
to be 5.1 x 10~5. The selected remedy in the ROD requires
extraction of ground water that exceeds the cleanup levels in
Table 12. However, if contaminants other than those listed for
ground water in Table 12 are detected, the selected remedy
requires calculation of the cumulative carcinogenic and
noncarcinogenic risks for all contaminants using the assumptions
found in Appendix B. If the cumulative carcinogenic risk exceeds
10~4 or the cumulative noncarcinogenic hazard index is greater
than one (1) , ground water extraction shall be continued.
The Revised Proposed Remedial Action Plan did not include
ground water cleanup levels for contaminants that pose
unacceptable noncarcinogenic risk at the Site, such as 2-
butanone. Cleanup levels for these contaminants have been
included in Table 12.
The proposed sediment cleanup levels in the Revised Proposed
Remedial Action Plan were based on human health risk for PCBs and
the upper limit of the 9.0th per cent ile of the common range of
values found in Eastern U.S. soils for lead, copper, and zinc.
Upon further review, EPA has determined that"the National Oceanic
and Atmospheric Administration (NOAA) Screening Guidelines for
Organics and Inorganics are more appropriate for protection of
ecological receptors at this Site. The sediment cleanup levels
in Table 12 of the ROD for copper and zinc are the NOAA Effects .
Range-Low (ER-L) values. These levels did not vary significantly
from the cleanup levels in the Revised Proposed Remedial Action
Plan. The copper cleanup level changed from 48.7 mg/kg to 34
mg/kg. The zinc cleanup level changed from 104 mg/kg to 150
mg/kg. The NOAA ER-L values for PCBs and lead are 23 ug/kg and
47 ug/kg, respectively. EPA has experienced difficulty achieving
these levels in other sediment cleanups at Superfund sites in
Region 3 and, therefore, has selected the levels found in Table
12 for these contaminants. In the case of PCBs, the sediment
cleanup level does not change from the level presented in the
Revised Proposed Remedial Action Plan (i.e., 1 mg/kg). The
cleanup level for lead changes from 33 mg/kg to 200 mg/kg.
For sites involving lead contamination, EPA recommends, as a
matter of policy (OSWER Directive #9355.4-12), that a soil
cleanup level of 400 mg/kg be used as an average to be attained
in residential areas. This cleanup level has been added to the
soil cleanup levels in Table 12 of the ROD.
c. Air Sparging and Soil Vapor Extraction
During the public comment period, several commentors
suggested the use of air sparging to address the VOCs in the
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saturated soils and ground water. EPA did not evaluate this
technology in the FS because air sparging would not address the
PCB and inorganic contaminants present in the ground water.
However, since most of the contaminants in the ground water are
VOCs, air sparging could be effective in reducing the operation
time for the ground water extraction and treatment system. Air
sparging would have to be implemented in combination with soil
vapor extraction and ground water extraction and treatment to
avoid simply transferring contaminants from one media to another.
There are several factors that would need to be investigated
during a treatability study to determine if implementation of air
sparging and soil vapor extraction would be possible. For
example, the type of soils present at the Site would need to be
evaluated to determine if adequate air flow can be achieved. The
impact of the shallow water table on operation of the system
would also need to be considered.
Because air sparging and soil vapor extraction, if
implementable at the Site, could reduce the time required for
operation of the ground water extraction and treatment system,
EPA is allowing for potential use of these technologies at the
Site. Section X.C.4. of the ROD identifies the circumstances
under which these technologies may be implemented.
D. RCRA Listed Hazardous Waste Issues
The initial Revised Proposed Remedial Action Plan
contemplated disposal of contaminated soils and sediments from
the Site at a landfill regulated under Subtitle D of RCRA. In
response to concerns raised during the comment period, EPA
revisited the issue and proposed that Site wastes be considered
"listed hazardous wastes" under RCRA and that, accordingly, such
wastes be disposed of at a 1 andf-ill regulated under Subtitle C of
RCRA and after such waste were treated to the extent necessary to
meet RCRA Land Ban Restrictions. The treatment requirements and
disposal restrictions associated with management of RCRA listed
hazardous wastes significantly increased EPA's cost estimate for
several of the remedial alternatives detailed in the initial
Proposed Plan. EPA accordingly issued a Revised Proposed Remedial
Action Plan on December 22, 1994. The Revised Proposed Remedial
Action Plan set forth the additional requirements and included
revised costs estimates for those alternatives affected by the
issue.
Following careful consideration of relevant comments
submitted during the second comment period, of information
relating to the source and generation of wastes found at the
Site, and of the implications of this issue on protection of
human health and the environment, EPA has decided to reverse its
proposed view, set forth in the Revised Proposed Remedial Action
Plan, that Site wastes be handled as RCRA listed hazardous
wastes. Rather, Site wastes will be tested to determine whether
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they warrant handling as RCRA characteristic hazardous waste
pursuant to 40 C.F.R. Part 261, Subpart C, and shall be handled
accordingly. The Responsiveness Summary found at Part III of
this Record of Decision presents comments relating to this issue
and the Agency's responses to such comments.
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RECORD OF DECISION
HH BURN PIT SUPERFDND SITE
PART III - RESPONSIVENESS SUMMARY
Comments raised during the public comment periods on the
Proposed Plan and the Revised Proposed Remedial Action Plan for
the HH Burn Pit Site are summarized in this Responsiveness
Summary. The first comment period was initially held from
December 21, 1993 to January 19, 1994 to address the Proposed
Plan. Upon request, the public comment period was extended until
February 18, 1994. A second comment period to address the
Revised Proposed Remedial Action Plan ran from December 23, 1994
through January 23, 1995. Upon request, this second comment
period was extended through February 22, 1995.
Oral comments were presented at the Proposed Plan Public
Meeting held on January 11, 1994. These comments and EPA's
responses are presented in Section I of the Responsiveness
Summary. A transcript of the first public meeting has been
included in the Administrative Record for the Site.
EPA received three letters from concerned parties on the
cleanup alternatives or other aspects of Site activity during the
first public comment period. One letter was from a local
resident concerned about the potential impact of site-related
contamination on his residence. The other two letters were
comments submitted jointly by several companies associated with
the Site (Company Group). The comments presented in these
letters and EPA's responses are presented in Section II of the
Responsiveness Summary. These letters have been included in the
Administrative Record for the Site.
The Company Group submitted additional comments after the
close of the first public comment period. EPA has reviewed and
responded to these comments in Section II of the Responsiveness
Summary. This letter has also been included in the
Administrative Record for the Site.
During the second comment period, EPA received several
letters from the Company Group that contained comments, pertaining
particularly to the issue of listed wastes. These comments and
EPA's responses are presented in Section III of the
Responsiveness Summary.
I. ORAL COMMENTS FROM JANUARY 11, 1994 PUBLIC MEETING
1) A resident commented that given the age of this site, the
contaminant plume is moving extremely slowly (only a couple
of hundred feet in 15 years). Another resident commented
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that we were treating the ground water as static, whereas
the ground water flows.
Response: EPA has estimated the rate of ground water
movement to be 20 feet per year in the overburden aquifer
and 1,640 feet per year in the bedrock aquifer. Ground
water movement, as a rule, does tend to be relatively slow,
especially when compared with typical surface water flow.
2) A resident commented that a dug well averages about 40 feet
with about 19 feet of water standing in them for domestic
use and was concerned that we had not placed wells in ground
water zones where the people in the area were using the
water.
•
Response: EPA installed 16 wells at various depths in order
to characterize the ground water at the Site. Eight wells
were installed to collect ground water from depths of 8 - 24
feet. Four wells collected ground water at depths of 30 -
60 feet and four wells collected ground water at depths of
75 - 105 feet. With this network of wells, EPA was able to
characterize both the overburden (shallow) and bedrock
(deep) aquifers present at the Site and evaluate horizontal
and vertical movement of contaminants. EPA also sampled
residential wells directly to determine if contamination was
present.
3) A resident commented that he had not read about a
distribution of the contamination at 50 to 200 feet in the
Proposed Plan.
Response: EPA responded that the main purpose of the
Proposed Plan was to present a brief overview of the
information. The Remedial Investigation Report, a copy of
which is available at the Ashland Library, gives more
specific and detailed information about the Site.
4) A resident expressed concern that EPA did not evaluate the
condition of ground water further away from the Site.
Another resident questioned whether there had been any
extrapolation from the area of highest contamination to the
wells further downgradient to determine how much _f urther the
plume might have extended and whether any modeling had been
done to assess this situation.
Response: EPA explained that the goal of the remedial
investigation was to find out if contamination is present
and, if so, how far it has moved. To do this, EPA installed
monitoring wells near the source of the contamination during
the first phase of investigation since this would be the
mostly likely area to find contamination in the ground
water. Since contamination was found, additional wells were
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installed during the second phase to estimate the outer
boundary of the contamination plume. These wells were
relatively free of contaminants; therefore, EPA determined
that additional wells at greater distances from the Site
were not necessary at the time. Figure 9 in the ROD
illustrates the estimated extent of the ground water plume
based on total VOC concentration. As indicated by the
dashed line, the data was extrapolated to some extent to
estimate the boundary of the plume.
Monitoring will continue at the Site during
implementation of the remedy. If the contaminant plume
appears to be migrating beyond the existing wells, EPA may
determine that installation of additional wells is
necessary.
5) Residents asked if there would be any more testing of the
residential wells in the community, how often such testing
would be done, and if any information obtained would be
furnished to the owners of the property.
Response: The ROD requires continued monitoring of the
nearest residential wells downgradient of the Site. The
details of the monitoring plans will be developed during the
design of the remedy. The results of any additional
residential well sampling performed will be made available
to the residents whose wells are sampled.
6) Several residents expressed concern that the contaminant
plume has reached their wells because some contamination was
detected.
Response: Twelve residential wells were sampled twice
during the RI. Beryllium was detected in one well at a
concentration of 5.8 ug/1, which exceeds the Safe Drinking
Water Act Maximum Contaminant Level (MCL) of 4.0 ug/1.
Trace levels of heptachlor epoxide and tetrachloroethene
were detected in two additional wells; however, levels were
below the MCLs. The well that contained heptachlor epoxide
(RES-2) is located in an east-southeast direction from the
Site and is hydraulically upgradient. Well construction
information indicates that the well produces water from the
overburden aquifer. These facts indicate that it is
unlikely that this well is being impacted by the Site.
The well containing tetrachloroethene (RES-5) is
located over a mile south-southwest of the Site on a hilltop
on the opposite side of the Black Haw Branch. Shallow
ground water most likely discharges to the Black Haw Branch
from both sides of the stream. Available well construction
information indicates that this home well is producing water
from the overburden aquifer which suggests that the well is
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isolated hydraulically from the Site.
Based on reported construction details, the well
containing beryllium (RES-7) produces water from the bedrock
aquifer. Beryllium was not detected in any of the on-site
bedrock monitoring wells. Therefore, the Site does not
appear to be a potential source of beryllium. The beryllium
could be due to natural conditions, or from some other
source.
7) A few residents expressed concern they had not received any
information from EPA concerning the results of the
residential well sampling.
Response: EPA did send letters to the residents whose wells
had been sampled to report the findings. It appears that
these residents did not receive their letters because the
mailing addresses EPA had were incorrect. Correct addresses
were obtained and another copy of the results were sent to
the proper addresses.
8) Residents expressed concern that the value of their homes
would be affected by the publicity of the Site. Residents
questioned if the county takes these circumstances into
consideration when it does a residential tax assessment and
if residents would be required to tell prospective buyers of
a house they are trying to sell that a hazardous waste site
is present in the area.
Response: While EPA understands these issues to be of
concern to the residents, the Superfund law does not
specifically address these issues. Concerns about local
taxes are best addressed at the local tax office. Local
real estate agents should be aware of any disclosure
requirements required by state laws or local regulations.
9) A resident expressed concern about the intermittent stream
and whether the alternative chosen by EPA would address
potential risks to someone drinking the water from the
stream.
Response: The intermittent stream does contain Site-related
contaminants, particularly PCBs that could pose a slight
risk to'people using the stream. However, contaminants in
the stream pose a greater risk to wildlife that use the
stream. The remedy selected by EPA for the Site will
address the contaminated stream sediments.
10) A resident expressed concern about who will pay the cost of
the chosen remedial alternative and if the property owner
would be contributing to the costs.
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Response: The Superfund law established several categories
of persons who may be liable to perform or finance EPA's
response actions. EPA has identified responsible parties
and intends to contact them concerning implementation of the
selected remedy. If these parties fail to implement the
remedy, EPA will conduct the cleanup using federal funds and
seek to recover the cleanup costs from these parties at a
later date. EPA does not currently consider any of the
residents as responsible parties.
11) A resident asked how the ground water would be treated and
what kind of impact would this cleanup have on residents
(e.g., noise, odor, etc.).
Response: Extraction wells with pumps would be used to
extract the water from the wells and an on-site treatment
unit would remove the contaminants from the water through
several physical and chemical processes. EPA does not
anticipate that nearby residents will experience any adverse
effects from the ground water treatment operation. The most
significant impact is likely to result from increased truck
traffic involved in transporting contaminated soils and
sediments from the Site for a period of time.
12) A resident expressed concern that 90 percent of his
immediate family lives within 300 yards of the Site and has
experienced a high incidence of cancer. He stated that over
the last 14 years his family has lost four members from
cancer and that another grandchild had cancer. He also
mentioned that cases of cancer had been reported in the
neighborhood across from him as well. The resident
questioned whether the Site had any bearing on this
incidence of cancer in the community.
Response: A health assessment was performed by the State in
1983, which determined at that point that the Site was not
linked with an increased incidence of cancer in the area.
EPA has contacted the Agency for Toxic Substances and
Disease Registry (ATSDR) about this resident's concern.
ATSDR has indicated that site conditions do not warrant
further health assessment activities. Cancer incidence is
often difficult to determine because there are so many
factors involved in cancer risks including, among-other
things, family backgrounds, life style, and places of work.
EPA provided a separate written response to this resident
and suggested that concerned residents contact the State to
inquire about follow up health assessments.
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II. WRITTEN COMMENTS RECEIVED DURING THE FIRST PUBLIC COMMENT
PERIOD
1) A resident expressed concern that his family was
experiencing health problems and wanted to know if this
could be due to Site ground water contamination even though
he lived upgradient of the Site.
Response: EPA monitored the ground water upgradient of the
Site and did not detect any contaminants present at
unacceptable levels. It would be unlikely that the health
problems experienced by this upgradient user are a result of
contaminated ground water from the Site.
2) A group of companies associated with the Site (Company
Group) commented that the nature and extent of contamination
has not been fully defined for the ground water, sediment,
and soil media at the Site.
Response: While EPA recognizes that the extent of
contamination in the soils and ground water is not fully
defined, EPA believes that the number and distribution of
samples collected in the RI provide an adequate
approximation of the extent of contamination in the
different media in order to select an appropriate remedial
alternative. It is common practice to collect additional
information to further define the scope of cleanup actions
during the Remedial Design (RD). The ROD indicates that
additional investigation shall be performed during the RD to
define the limits of excavation. Additional investigation
may also be needed to properly locate the ground water
extraction well network.
3) The Company Group stated that the nature and extent of
contamination in surface soils has not been fully defined to
the west of the berm. Limited contaminant distribution data
exists between SS-9 and SS-11. As a result, the volume of
soil to be excavated and associated costs could be
significantly underestimated.
Response: The surface water runoff is the primary mechanism
for transport of contaminants to the area west of the bermed
disposal area. EPA collected one surface soil s-ample (SS-
10) south of the intermittent stream draining the disposal
area and ten sediment samples in and along the intermittent
stream immediately west of the bermed disposal areas and
along the first logging road west of the disposal area. EPA
believes this data adequately characterizes the nature and
extent of contamination in the area west of the bermed
disposal area. Because surface water flow has been diverted
from the intermittent stream by the first logging road, EPA
is requiring additional investigation during the Remedial
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Design to determine the limits of necessary excavation.
Sediments containing Site-related contaminants are not
expected to have migrated significant distances and are
likely to be confined to a few depositional areas. In
addition, contaminants in this area are expected to be
confined primarily to a few inches in depth. While EPA
agrees the volumes of soils and sediments could be higher
than those estimated, EPA does not believe the change in
volume would be of a magnitude that would cause the Agency
to select another alternative.
4) The Company Group stated that the berm surrounding the
former burn pits should also be sampled to evaluate whether
or not it has been impacted by past Site activities. Should
the berm soil contain constituents above the proposed
cleanup levels, a significant increase in the volume of
soils requiring remediation could be realized that has not
been previously addressed.
Response: The berm surrounding the disposal area was
reportedly constructed of native soil at the time the area
was originally, cleared prior to actual disposal. Therefore,
EPA did not sample the berm soil during the RI. Soil in the
berm will be sampled during implementation of the cleanup to
determine the final disposition of these soils. While EPA
agrees that the volume of soil to be addressed could
increase if the berm soil is contaminated, EPA does not
believe the change in volume would be of a magnitude that
would cause the Agency to select another alternative.
5) The Company Group stated that, based on the laboratory
analytical data from the soil borings, the vertical extent
of residual contamination has not been adequately defined
beneath the Site. This is evidenced by the elevated VOC and
semi-volatile concentrations detected in the terminal sample
collected from borings BH-8 and BH-9.
Response: The data collected from the soil borings
indicated that VOC and semi-volatile contamination extends
below the water table. VOC and semi-volatile contamination
was also found in the ground water. This information was
sufficient for EPA to effectively evaluate remedial
alternatives. Further information on the vertical extent of
VOC and semi-volatile contamination in the soil would be
useful, but not necessary to evaluate appropriate remedial
alternatives.
6) The Company Group contends that a detailed fracture trace
analysis (FTA) is critical to the proper siting of
monitoring well locations in a fractured bedrock system.
The FTA conducted for the Site only used single aerial
photographs in an attempt to interpret surface and
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subsurface features. The Company Group believes this
approach can be misleading when trying to interpret
topographical features that exhibit a three-dimensional
image when viewed stereoscopically.
Response: A fracture trace analysis was performed to help
identify any potential lineaments with use of a single
aerial photograph. Lineaments can be interpreted from one
aerial photograph and use of a stereoscope with two aerial
photographs would only aide the interpreter in visualizing
three-dimensional topographic features. The interpreted
lineaments must be confirmed in the field to verify that it
is a potential fracture trace and not some man-made feature
(such as power line, sewer line, or tilled earth). In
addition, the bedrock monitoring wells installed during the
second phase of the RI were located along the interpreted
lineaments and appear to have successfully intersected
water-bearing fractures in the shallow portion of the
bedrock. With the installation of additional bedrock
monitoring wells, another fracture trace analysis can be
performed with the use of a stereoscopic analysis for a
larger area surrounding the Site and to confirm the
interpretations of the RI, if necessary.
7) The Company Group stated that there are currently no deep
overburden or bedrock wells directly downgradient of the
former burn pits in the area of MW-4 and in the area of MW-
5. They contend that this is a significant data gap given
the proposed remedial alternative of ground water extraction
and treatment. They contend that further delineation of the
nature and extent of contamination in this area is warranted
during the RI/FS since the ground water concentrations used
to assess the remedial alternatives may not be
representative and knowledge" of downgradient concentrations
may affect the selection of ground water treatment
technologies.
Response: EPA installed four deep overburden (saprolite)
wells and four bedrock wells at the Site, as well as eight
shallow wells to characterize ground water contamination.
While a deep overburden or bedrock well was not located
directly down gradient from MW-4 and MW-5, EPA believes the
data from the existing monitoring well network characterizes
the nature and extent of the ground water contamination in a
manner sufficient to permit evaluation of ground water
alternatives. Additional ground water investigation is
typically necessary during the Remedial Design to properly
design the ground water extraction well network.
8) The Company Group stated that, based on the well completion
depths included in the RI, ground water quality in a 26 to
35 foot interval between auger refusal and competent bedrock
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has not been adequately defined. This zone of highly
weathered, densely fractured bedrock is generally referred
to as the transition zone and can be the primary flow zone
in piedmont aquifers (Powell and Abe, 1985). This transition
zone should be addressed in order to adequately define the
nature and extent of contamination.
Response: The Powell and Abe reference is a regional
description of ground water availability in a typical
Piedmont Physiographic geologic setting. This reference
indicates that when the overburden is saturated for a
significant thickness, as is the case at the Site, the
overburden yields a significant amount of water for drinking
water supply. At the Site, the overburden aquifer is
approximately 60 - 70 feet in saturated thickness (Figure 4-
3 and Appendix B of the RI).
Since the overburden, rather than the transition zone,
appears to be the primary flow zone based on Site-specific
information, shallow and deep overburden monitoring wells
were installed during the RI. The criteria for installing
deeper saprolite monitoring wells was that during drilling,
if contamination was observed in the deeper portion of the
overburden, then monitoring wells would be installed with
the well intake across the area with the observed
contamination. Residential wells which are most likely
producing from the overburden aquifer were reported to be no
greater in total depth than 50 feet below ground surface.
Consequently, the deep overburden wells were installed to a
total depth of 55 feet with the well intake interval at
anywhere between 30-55 feet (See Table 3-6 in the RI).
As stated previously, additional ground water
investigation is typically necessary during the Remedial
Design to properly design the ground water extraction well
network. Further characterization of the transition zone
may be appropriate at that time.
9) The Company Group stated that no rock cores or samples were
obtained to confirm or evaluate fracture locations,
orientations, or other characteristics. The Company Group
contends that the presence of fractures and water bearing
zones were based on crude observations made by tire driller
and on-site geologist. Because fracture identification is
essential in defining the contaminant distribution in a
fractured bedrock aquifer system, coring, geophysical logs,
and packer tests are an important element in evaluating the
flow regime in a bedrock aquifer system. These techniques
were not employed at the Site.
Response: The objective of the bedrock monitoring wells
installed during Phase II of the RI was to monitor the water
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quality of the shallowest water-bearing fracture(s)
encountered during drilling. All the bedrock monitoring
wells constructed during Phase II have relatively short well
intake intervals (20 feet) and are constructed across zones
which the driller and geologist identified during drilling.
While coring rock, borehole geophysical logging, and packer
tests would provide valuable data with respect to fracture
distribution and yield of these fractures, identification of
water-bearing zones and yield are normally performed by the
driller and on-site geologist during the drilling process.
It is common industry practice to rely on observations by
both an experienced driller and geologist concerning
borehole characteristics. EPA agrees that some of these
techniques would be very useful in evaluating the extent of
contamination in the bedrock aquifer and may be appropriate
for inclusion in additional ground water investigation
conducted during the Remedial Design.
10) The Company Group contends that when air rotary drilling is
used in fractured bedrock systems, thin water bearing zones
may not be discernible due to the air pressure in the
borehole which sometimes exceeds the hydraulic pressure of
the water-bearing zone. Additionally, they state that the
combination and quality of dust in the air is sufficient
enough to remove the small amount of moisture in a thin
water-bearing zone. Therefore, these zones may have been
masked during the drilling of the bedrock wells at Site.
Response: Air rotary is commonly used as a drilling
technology at Superfund sites as well as by the
environmental industry when drilling monitoring wells.
While very low-yielding thin water-bearing zones may not be
easily discernible while drilling with air rotary, the Phase
II bedrock monitoring wells were constructed with the well
intake open for 20 feet within the upper 30 feet of .
competent bedrock. The goal of the Phase II bedrock
monitoring wells was to identify the shallowest significant
water-bearing zone (greater than one gallon per minute) and
screen the well across this zone based on driller and
geologist observations. The drillers and on-site geologist
did notice significant water-bearing zones within the top 30
feet of competent bedrock and, consequently, all Phase II
monitoring wells were constructed in the upper portion of
competent bedrock.
11) The Company Group contends that land use restrictions could
be placed on this property which would provide for
excavation restrictions and result in a less restrictive PCB
clean-up goal for soils.
Response: EPA does not favor land use restrictions to limit
future property use at this Site. Land use currently in the
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vicinity of the Site is rural residential. The Hanover
County Comprehensive Plan does not propose any changes in
the vicinity of the Site that would attract more intense
residential development (i.e., public sewer and water); nor
does the plan advocate changes that would discourage
continued construction of rural single-family homes (i.e.,
targeted future commercial or industrial use). Land use
restrictions based on an incomplete cleanup would
permanently reduce the options available for future use of
the property. Such restrictions would additionally run
counter to the statutory preference for reducing
volume/toxicity of wastes through treatment. This result is
consistent with newly issued guidance entitled "Land Use in
the CERCLA Remedy Selection Process" [OSWER Directive No.
9355.7-04 (May 25, 1995)] .
12) The Company Group identified three errors in the
calculations for the VOC cleanup goals presented in Tables
2-1 and 2-6 of the FS Report:
a) Only ten of the 52 soil samples were analyzed for Total
Organic Carbon (TOC). However, when calculating the
mean percentage TOC, the values were totaled and
divided by 52 rather than ten. Their correct mean TOC
percentage is 0.0018 rather than 0.0004,
b) Incorrect units were reported for the Koc and Kd
values. The units should be in ml/g or L/kg rather
than 1/mg.
c) The Kd values presented are incorrect. There appears
to have been errors made when converting the numbers to
scientific notation.
Response: In response to this comment:
a) The Company Group is correct in that the mean TOC
(total organic carbon) of the ten subsurface soil sample
results which were analyzed for TOC would be 0.0018 or
0.002. It appears, however, that Koc was multiplied by
0.004 rather than 0.0004 foe. Therefore, using the mean TOC
concentration of 0.002 would lower the estimated contaminant
concentration calculated for soil to be protective of ground
water (as stated in Table 2-6 of the FS Report) by half of
that listed.
b) The correct units for Koc and Kd would be L/kg. This
error was evaluated and it is apparent that the use of the
incorrect unit did not impact the estimated contaminant
concentrations in soil for protection of ground water that
are listed in Table 2-6 of the FS Report.
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c) The .Kd values are incorrect probably due to multiplying
by a foe of 0.0004. In using the average TOC of 0.002. as
the foe, the corrected Kd values would be half of the values
depicted in Table 2-6 of the FS Report.
As noted, the values derived in these calculations would be
lower than if the correct method had been used. However,
since this modeling effort is hot being utilized for the
development of cleanup standards, the values are not
relevant to the chosen alternative.
13) The Company Group contends that the approach used to
establish VOC cleanup goals in soils is overly simplistic
and resulted in extremely conservative soil cleanup goals.
Relying on EPA's Pollution Technology Review, the Company
Group states that the inorganic composition of deep aquifer
materials can have a larger effect on sorption than the
organic content which is typically low (<1%). When compared
to the EPA Region 3 Risk-Based Concentration values for
residential soil, the VOC cleanup goals presented in the FS
for protection of ground water are, on average, three orders
of magnitude lower. The Company Group recommends that site-
specific data be generated to develop cleanup goals (i.e.,
column testing) or that, at a minimum, a more sophisticated
model that includes dilution and attenuation factors be
employed in calculating appropriate cleanup goals.
Response: The discrepancies have been noted and the
estimated contaminant concentrations in soil in Table 2-6 of
the RI Report would change to half of the originally
estimated concentrations. EPA agrees that the method
employed to estimate preliminary soil action levels
protective of ground water is a conservative approach (i.e.,
predicts the lowest soil concentration allowable for ground
water protection). However, this method of estimating soil
clean-up levels has been used at several other Superfund
sites (EPA/540/2-89/057, 1989) and is appropriate here as
well. The estimated clean-up numbers protective of ground
water, are preliminary numbers for unsaturated soils which
would normally be refined during the Remedial Design
investigation. However, since the selected remedy does not
require the use of soil cleanup goals for VOCs, this will
not be necessary. —
As a further note, it is not uncommon to establish soil
clean-up levels protective of ground water for some
contaminants which are several orders of magnitude lower
than the risked-based concentration levels calculated for
residential soils. The risk-based concentration for
residential soil was not developed to be protective of
ground water. On the whole, risk-based concentrations for
drinking water are much lower for most chemicals than risk-
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based concentrations for residential soils. For example,
the risk based concentration for toluene in residential
soils is 16,000 mg/kg (ppm) while for drinking water it is
several orders of magnitude lower at 750 ug/1 (ppb). In
addition, VOCs are very mobile and have a tendency to move
more rapidly through soil to the ground water.
Consequently, estimated soil clean-up concentrations for
protection of ground water derived from modeling for this
group of compounds tends to be much lower than risk-based
concentrations developed for residential soils.
14) The Ontario Ministry of Environment Sediment Quality
Criteria was utilized to determine the PCB clean-up goal for
sediments (0.041 mg/kg). The Company Group believes that
this is inappropriate and that less restrictive standards
could be calculated based on site-specific risk and an
evaluation of PCB speciation. For instance, Aroclor 1248
has been assigned the same risk level as Aroclor 1260 when,
in fact, it is less toxic.
Response: Upon further review, EPA has determined that the
National Oceanic and Atmospheric Administration (NOAA)
Screening Guidelines for Organics and Inorganics are more
appropriate for protection of ecological receptors at this
Site based on current information. The sediment cleanup
levels in Table 12 of the ROD for copper and zinc are the
NOAA Effects Range-Low (ER-L) values. The NOAA ER-L values
for PCBs and lead are 23 ug/kg and 47 ug/kg, respectively.
EPA has experienced difficulty achieving these levels in
other sediment cleanups at Superfund sites in Region 3 and,
therefore, has selected a PCB cleanup level of 1 mg/kg and a
lead cleanup level of 200 mg/kg.
15) The Company Group stated that the surface water cleanup goal
for Aroclor 1260 is below the analytical quantitation limit.
Therefore, in- actuality, the practical cleanup level would
be. the detection limit.
Response: EPA has not established cleanup levels for
surface water in the ROD since the selected remedy does not
require any direct remediation of surface water. Surface
water is expected to achieve acceptable levels after
contaminated sediments have been removed. —
16) The Company Group states that the surface soil sample at SS-
10 and the terminal soil samples from borings BH-8 and BH-9
exceed proposed cleanup standards, but volume estimates for
excavation do not include these soils. They contend that
the volume of material to be excavated and the associated
costs could be significantly underestimated.
Response: The factor limiting depth of excavation will be
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the water table, not the depth of contamination.
Contaminants present in the saturated soil will be addressed
through the ground water extraction and treatment process.
The comment concerning volume of surface soil to be
excavated was addressed previously in Comment #3 of this
section.
17) The FS states that soils found to contain PCBs at
concentrations below 50 mg/kg would be disposed of as a
special waste by the Virginia Solid Waste Management
Regulations and would be handled in accordance with VR 672-
20-10, §8.7. In general, these regulations indicate that
soils can be disposed of in a permitted sanitary or
industrial (Subtitle D) landfill in Virginia if they pass
TCLP, have total organic halogens (TOX) concentrations less
than 100 mg/kg, have total petroleum hydrocarbon
concentrations less than 1,500 mg/kg, and total BTEX
concentration less than 10 mg/kg. The Company Group
contends that it is unlikely that a landfill can be found
that will accept the contaminated Site soils at the price
used in the cost estimate.
Response: The disposal costs used in Alternative El were
those available at the time the FS was developed. Costs may
have increased since completion of the FS; however, for
purposes of comparison, EPA believes the cost estimates
provided are appropriate.
18) Stabilization was only considered in combination with steam
stripping. The Company Group stated that
stabilization/chemical fixation would seem to be better
applied only to the upper soils (top 6 feet) and sediments
where the constituents of concern are predominantly PCBs and
metals. With this limitation, excavation and above ground
fixation may be more appropriate than the in-situ
technology, other technologies could be used to address the
deeper materials where the focus is predominantly VOCs.
Response: While the PCBs and metals may be the predominant
contaminants in the upper soils, VOCs and semi-volatile
organic compounds are present at levels that would require
treatment if the soils were to remain on-site.
Stabilization and chemical fixation alone would not be
sufficient to address the upper soil.
19) The Company Group stated that air sparging was not
identified and evaluated as a potential remedial technology
to address the soils and shallow ground water impacted by
VOCs.
Response: The commentor is correct that the Feasibility
Study did not evaluate air sparging as a technology for
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cleaning up soils and shallow ground water impacted by VOCs.
However, while this may be an innovative technology to
remediate VOC contamination, this technology could not .
address the PCBs, pesticides, and metals contamination which
have been detected in soil and ground water at the Site.
Since a large portion of the ground water contamination
consists of very high concentrations of VOC contaminants,
the selected remedy allows for use of (but does not require)
an air sparging and soil vapor extraction system to enhance
the overall performance of the ground water treatment system
(See Section X.C.4. of the ROD).
Air sparging would have to be implemented in
combination with soil vapor extraction and ground water
extraction and treatment to avoid simply transferring
contaminants from one media to another. A treatability
study would have to be performed during the Remedial Design
to determine if this technology would be effective. Several
factors could impact the implementability of these
technologies, including the type of soils present at the
Site and the impact of the shallow water table on operation
of the system. EPA will allow use of these technologies,
however, if the treatability study demonstrates that they
can be successfully implemented.
20) A treatment cost of $300/CY for in-situ steam stripping of
the soils plus an additional $180/CY for in-situ
stabilization seem excessive. Based on discussions with
treatment vendors, the Company Group contends that treatment
costs associated with this technology are generally in the
$200 to $250/CY range.
Response: The treatment costs for in-situ steam stripping
and in-situ stabilization were those available at the time
the FS was developed. Costs may have decreased since
completion of the FS; however, for purposes of comparison,
EPA believes the cost estimates provided are adequate.
21) For low temperature thermal stripping (LTTS), EPA's
contractor used a unit treatment cost of $350/CY (approx.
$455/ton) to treat the soils for volatile and semi-volatile
contaminants only. The Company Group contends that this
seems excessive as treatment estimates of $225 to-$260/ton
to £reat similar wastes for both volatiles and metals have
been quoted in the past.
Response: The treatment costs for low temperature thermal
stripping were those available at the time the FS was
developed. Costs may have decreased since completion of the
FS; however, for purposes of comparison, EPA believes the
cost estimates provided are adequate.
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22) The Company Group contends that the assumption of future
residential use on the Site is unreasonable and that remedy
selection for Superfund sites should be based on likely
future use.
Response: EPA believes it is reasonable to consider
residential development as a potential future use for the
Site. The land use currently in the vicinity of the Site is
rural residential. The Hanover County Comprehensive Plan
does not propose any changes in the vicinity of the Site
that would attract more intense residential development
(i.e., public sewer and water); nor does the plan advocate
changes that would discourage continued construction of
rural single-family homes (i.e., targeted future commercial
or industrial use). There are currently residential
properties adjacent to the Site, including a newly
constructed home along the Site access road. Several
potential residents interested in building homes in the area
indicated their concern regarding property value during the
public meeting. This result is consistent with newly issued
guidance entitled "Land Use in the CERCLA Remedy Selection
Process" [OSWER Directive No 9355.7-04 (May 25, 1995)].
23) The Company Group contends that application of the
linearized multistage model may not be appropriate for PCBs.
Response: While the Company Group is correct that the
subject model is not appropriate in cases where the
contaminant is not a genotoxic and is not an initiator, it
should be noted that the mechanism of action by PCBs (and
individual congeners of PCBs) has not been established. In
the absence of adequate information to the contrary, the
linearized multistage model continues to be applicable.
24) The Company Group contends that distinctions should be made
in the tumorigenic potency of different Aroclors.
Response: As stated in the Integrated Risk Information
System (IRIS): "Although it is known that PCB congeners vary
greatly as to their potency in producing biological effects,
for purposes of this carcinogenicity assessment Aroclor 1260
is intended to be representative of all PCB mixtures. There
is some evidence that mixtures containing more highly
chlorinated biphenyls are more potent inducers of
hepatocellular carcinoma in rats than mixtures containing
less chlorine by weight."
Hence, the Agency does note that there is some evidence
that mixtures containing more highly chlorinated biphenyls
are more potent. However, since slope factors are not
currently available for individual congeners of PCBs (i.e.,
a slope factor is available for Aroclor 1260 only at this
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time), it is conservatively assumed that all of the PCBs are
at least as toxic as Aroclor 1260.
25) The Company Group contends that the scaling factor used by
EPA to relate doses in animals and humans is inappropriate.
Response: It is agreed that the Agency currently recommends
that the cross-species scaling factor for carcinogenic risk
assessment be expressed in terms of body mass raised to the
3/4 power (i.e., mg/kg3/4/day). The recommended use of the
3/4 power scaling factor was made in order to achieve
consistency and uniformity among the different Federal
Agencies (e.g., ATSDR, FDA, EPA, etc.). The consensus in
the Agency and in the scientific community is that the use
of a 3/4 power scaling factor for body mass presents a
better rationale for matching doses between sizes across
species. The Agency has not yet finalized the policy to use
the 3/4 power as a scaling factor for body mass. In
addition, the Agency is expected to continue to consider use
of the 2/3 power as valid and is not likely to require that
all current toxicity criteria be recalculated using the 3/4
power scaling factor for body mass. Furthermore, the
difference in the resultant slope factor when a 2/3 power or
3/4 power is used as a scaling factor for body mass is only
a factor of two which is generally not significant.
Since EPA believes that the previous policy was valid,
and given all the uncertainty and the insignificance that a
factor of two will make in the resultant slope factor, the
Agency is not inclined to make a change in the scaling
factor used to calculate the slope factor for PCBs.
26) The Company Group contends that the potency estimates for
different aroclors should be based on the recent
reevaluation of liver histopathology.
Response: The Agency's Office of Research and Development
(ORD) is currently reviewing this data. It is not known
when a final recommendation will be made.
27) The Company Group contends that, overall, the available data
on PCB tumorigenicity indicate that alternative slope
factors are scientifically warranted. —
Response: As stated previously, the Agency recognizes that
there may be differences in the carcinogenic potency of
different PCB congeners. The new data currently available
which was not previously used in the assessment of the slope
factor is currently under review.
28) The Company Group contends that the use of an absorption
factor of 0.06 for PCBs is overly conservative.
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Response: It is clearly stated in the Dermal Exposure
Assessment Guidance (1/92) that the 1.3% absorption factor
(absorption factor recommended by the Company Group) is a
value obtained for low organic carbon content soil. The
total percent absorbed at 24 hours in vitro in human skin
was 1.33%. This value was adjusted to reflect differences
between absorption in vivo and in vitro in the rat,
producing an estimate of 2.1% absorbed and bound to the skin
after 24 hours for PCB applied in 6 mg soil/cm2.
Note that absorption from high organic carbon content
in soil was tested in vitro only in the rat. The Agency
adjusted the estimated percent of PCB absorbed from low
organic carbon content soil in human skin to reflect
absorption from high organic carbon content soil. The
estimated percent absorbed is 0.63%. The range of
absorption is therefore between 2.1% for low organic content
soil to 0.63% for high organic content soil. EPA decided
"that any final recommendations for percent absorbed should
span at least one order of magnitude to reflect the
uncertainty." The final recommendation for percent PCB
absorbed from soil is 0.6%-6%. Therefore, the use of 6%
absorption for PCBs in the risk assessment is appropriate
and consistent with Agency guidance. The use of 6% is
likely a conservative estimate but also consistent with
Agency policy to use conservative estimates in the risk
assessment when limited data are available to make a more
refined estimate.
29) The Company Group contends that the alternative analysis of
the PCB surficial soil data is inappropriate.
Response: The use of the Pfiase I data in the risk
assessment is appropriate given that this data represent
surface soil sampling data which was not collected during
the Phase II sampling round. The fact that the levels of
PCBs are higher in the Phase I analyses indicate only that
PCBs are present at higher levels in surface soil than in
subsurface soil. Note that Phase II data include data from
boreholes (0-2 ft, 2-4 ft, etc.), while Phase I data include
data from surface soil (e.g., 0-15 cm or - 6 inches).
Hence, the use of only Phase I data to determine --risk from
surface(soil contact is appropriate.
30) The Company Group contends that the assumption of incidental
ingestion (hand-to-mouth) exposure to chemicals in surface
water is unreasonable and based on estimates of ingestion
while swimming.
Response: It is agreed that this exposure route is probably
not likely given that the highest water level of the stream
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is not likely to be greater than one foot. However, at the
time of the assessment, it was not clear how high the water
levels would be, how much it would rain in the future,
whether or not there were going to be significant time
periods of dryness, etc. To be conservative, it was decided
that it was necessary to include this exposure route in the
assessment; albeit, we assume lower levels of water
ingestion (e.g., 0.01 1/hr. instead of 0.50 1/hr Agency
default) to account for the fact that swimming was probably
not a likely scenario.
31) The Company Group contends that incidental ingestion of
contaminated sediments is an unreasonable exposure pathway
and is improperly based on soil ingestion data.
Response: EPA believes that this exposure scenario is
likely to occur, especially when the stream is dry. It is
agreed, however, that the average soil ingestion parameters
could probably be lower. At the time of this assessment,
however, no other exposure parameters were available for
use. Draft EPA guidance does currently recommend the use of
100 mg/day for a child and 50 mg/day for an adult as average
soil ingestion exposure parameters. However, modification
of the exposure parameters in the existing risk assessment
will not result in a significant change in the risk estimate
previously calculated.
32) The Company Group questioned the philosophy of the
reasonable maximum exposure (RME).
Response: RME has been used at EPA since 1989. It is
recognized that compounding a number of conservative values
for exposure parameters in the baseline risk assessment can
result in a characterization of potential exposure that
cannot reasonably be expected to occur. However, that is
precisely why the average (central tendency) risk estimate
was calculated using central tendency exposure parameters
available to us at the time of the assessment. The average
risk estimate also indicates that the Site poses
unacceptable carcinogenic and noncarcinogenic risks.
33) The Company Group contends that sample concentration
distributions should have been prepared to support (or
refute) the assumption of normally distributed data.
Response: In general, EPA prefers that the arithmetic mean
be used in lieu of the geometric mean in cases where the
sample size is small and not sufficient for determining the
shape of the distribution present. This is the apparent
case here. Note that the geometric mean is a biased
estimator of the true mean if the distribution is not log
normal. Given that the data sets were small and the data
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34)
from Phase I and Phase II were sampled independently and
with different sampling designs, it was not possible to
combine the two data sets. For example, while Phase I PCS
sampling points were taken randomly across the Site within
the bermed area. Phase II PCB sampling points were taken on
a systematic grid pattern using bias sampling techniques
(i.e., was not random) within the bermed area. Additional
samples were taken in each burn pit area, primarily to
investigate the vertical extent of contamination. In these
cases, it is not appropriate to combine the data to achieve
a greater sample number, especially for surface soil
samples. The most conservative assumption in this case is
to assume a normal distribution.
The Company Group stated that Phase I and Phase II data used
to estimate exposure concentrations are not clearly shown.
Response: It is agreed that the Phase I and Phase II data
used to calculate the concentration term are not clearly
defined in the baseline risk assessment. Note that
duplicate sample data points were averaged. In cases where
the contaminant was detected in one sample but not detected
in other samples, one-half the detection limit was used in
the calculation of the concentration term. ,The Phase I and
Phase II data used are as follows:
Phase I Surface soil (0-6 inches): SS1A/1B, SS2A/2B,
SS3A/3B, SS4A/4B, SS5A/5B, SS6A/6B
Phase I and Phase II Boreholes (0-2 feet)t
Phase I Phase II
NE-1A
NE-2A
NE-3A
W-4A
W-5A
W-6A
MW-2A
BH-1A
BH-2A
BH-3A
BH-4A
BH-5A
BH-6A
BH-7A
BH-8A
BH-9A
BH-10A
BH-11A
BH-14A
BH-15A
BH-16A
BH-17A
BH-18A
35) The Company Group stated that based on the discussion on
page 8-5 of the RI, it was not possible to determine how the
U-flagged data values were used.
Response: The statement on page 8-5 discussing the
treatment of U-flagged values is incorrect. All
contaminants that were detected at hazardous levels at the
Site were assigned 1/2 the detection limit in cases where
individual samples showed a non-detect level.
36) The Company Group questioned the use of cleanup levels that
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are less than contract required quantisation limits.
Response: The cleanup levels for ground water have been
established at the minimum level at which the entire
analytical system gives a recognizable signal and acceptable
calibration point. Cleanup levels for surface water have
not been established since the selected remedy does not
require direct remediation of surface water.
37) The Company Group contends that on-site leachate/runoff
samples should not be considered representative of aquatic
habitats.
Response: It is agreed that on-site leachate/runoff samples
should not be considered representative of aquatic habitat.
However, on-site leachate/runoff is a pathway of contaminant
movement into the aquatic habitat. Moreover, on-site
leachate/runoff, whether it is transported via a permanent
stream, an intermittent stream, or merely an overland runoff
drainage ditch, still represents a habitat where potential
exposure to contaminants by ecological receptors (permanent
or migratory) could occur. Therefore, EPA believes that on-
site leachate/runoff samples are appropriate for use in
evaluating ecological risk from Site-related contaminants.
38) The Company Group questions why the bioassay test results
and aquatic and vegetation surveys were not used in the
ecological assessment. They further contend that sediment
remediation may not be necessary because the surveys
conducted during Phase II suggest no significant risk to
aquatic organisms offsite and that there is no true aquatic
habitat on the Site.
Response: The ecological risk assessment performed for the
Site used an approach similar to that used to quantitatively
assess human health risks. Therefore, surface water and
sediment chemical data, rather than bioassay results or
aquatic and vegetation surveys, were the appropriate input
parameters for calculating quantitative risk values. The
purpose of the aquatic and vegetation surveys was to
characterize the ecosystems and habitats of the area. It is
incorrect to attempt to use such characterizations as a
basis for calculating ecological risk. The bioaseay test
results and the aquatic and vegetation surveys were
considered along with the quantitative risk values to
evaluate the overall ecological impacts to the Site. The
Company Group acknowledges this, in fact, in the next
comment.
Even if there were no offsite aquatic impacts nor
onsite aquatic habitat, this would not eliminate the need to
remediate contaminated sediments. Contaminants have
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migrated from the bermed disposal area to the intermittent
tributary draining .the area and downstream to the Black Haw
Branch. Continued migration of contamination will continue
to occur unless the contaminated sediments are remediated.
39) The Company Group contends that although the data presented
in Tables 5-37 and 5-38 of the RI indicate toxicity at low
dilutions of the samples collected, it is unreasonable to
utilize this information in an ecological assessment
because, as indicated in the previous comment, there is no
suitable habitat for aquatic organisms on the Site.
Response: As indicated in the previous comment, EPA is
concerned about potential impacts to downgradient receptors,
not just impacts to receptors in currently contaminated
areas. Therefore, EPA believes the toxicity data does have
relevance to the overall ecological assessment.
40) The Company Group contends that the reference toxicant
portion of the sediment bioassay was run for only 96 hours
and thus does not truly show that the test system has been
validated.
Response: The reference toxicant is an acute test used to
verify the viability and response of a test organism
population through time in the lab. The test concentrations
should bracket the predicted LC50. In this case, the 96-hr
LC50 was the desired outcome. The toxicity test for
Hyalella azteca and Chironomus tentans are considered
acceptable and valid if the per cent survival is greater
than 80% and 70%, respectively, in the control chamber. The
toxicity tests performed for the Site meets this criteria.
41) The Company Group contends that although toxicity was
observed in the Phase II bioassay data, it is limited to
samples very close to the bermed disposal area and suggests
no potential risk to macroinvertebrates that may potentially
occupy the ephemeral stream further west of the disposal
area..
Response: Based on Page 10 (chapter 9 of the RI Report),
only a macroinvertebrate survey of the ephemeral stream was
conducted. The bioassay data was collected near--the bermed
area and cannot be compared to the locations in the
ephemeral stream. Therefore, its results cannot be used to
either dismiss or demonstrate toxicity at some other
location. In addition, the area may not be acutely toxic,
but there may be chronic effects which are not known at this
time. In the absence of this actual bioassay data, we used
the conservative approach and available chemical
information. In doing so, reasonable worst-case assumptions
were made to provide a conservative estimate. This
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typically results in an assessment which overestimates
rather than underestimates the risks of adverse ecological
effects at the Site.
The RI Report risk assessment concluded that the bermed area
of the Site is a source of environmental contamination in
soil, sediment, and surface water on and near the Site, and
that this contamination may present the potential for
adverse toxicological effects to various taxa in the bermed
area and in sediments downstream from that area.
A hazard index (HI) greater than one (1) would indicate the
potential for chronic or acute toxicological effects to a
given ecological receptor. The majority of His in each
matrix and for all relevant contaminants of concern exceeded
one (1), with numbers as high as 497 for arochlor in
sediments.
42) The Company Group stated that the RI should have provided
more information on the rationale for choosing the
ecological exposure models and associated assumptions.
Response: Ecological receptors and potential exposure
pathways were evaluated for inclusion in the ecological
assessment (EA) on the basis of the Site contaminants, -
affected media identified, and the characteristics of
receptors. The following exposure pathways were chosen for
evaluation in the risk assessment:
• Aquatic biota in the unnamed ephemeral tributary
and semi-aquatic species were chosen due to their
potential exposure to elevated metal levels and
PCB concentrations in the sediment and surface
water.
• Plants growing on top of and along the edge of the
Site were chosen due to the observation of
stressed vegetation in some areas. This exposure
pathway was incorporated into the secondary
consumer pathway.
• Secondary consumers, especially small mammals
using the Site, were chosen due to their potential
exposure to elevated levels of metals, PCBs, and
phthalates in the soil.
• Migratory birds using the Site were chosen due to
their potential exposure to elevated levels of
PCBs and metals contaminants in the soil and
sediment.
Receptors and exposure pathways excluded from evaluation in
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the EA were upland tertiary consumers and top carnivores due
to the size of the Site relative to the necessary home range
for these species. The potential for significant exposure
of these groups to Site contaminants is considered minimal.
Copper, lead, and zinc were found at elevated concentrations
in surface water samples collected up to the second logging
road along the unnamed ephemeral tributary that drains the
disposal area. Beyond the second logging road, only lead
and zinc are present, though at concentrations substantially
lower than the samples collected before the second logging
road. Arochlor 1260 was detected in six of the 15 surface
water samples collected from the unnamed ephemeral tributary
prior to the second logging road. Therefore, the EA focused
on copper, lead, zinc, and Arochlor 1260 in surface water.
In sediment, lead and copper were found in elevated
concentrations along the unnamed ephemeral tributary
immediately below the disposal area and downstream to the
second logging road. Arsenic, aluminum, chromium, and zinc
also were present at elevated concentrations along the same
portion of the tributary. Of these six contaminants, lead
and copper are present in substantially higher
concentrations and are more widely distributed (i.e., they
are present in elevated concentrations in more of the
samples collected from the above-mentioned location).
Therefore, even though all six metals are of concern, lead
and copper received greater attention in the EA. Arochlor
1260 was detected in 14 of the 22 sediment samples collected
in the unnamed ephemeral stream and was also addressed in
the EA.
In soil, copper, lead, and zinc were found at concentrations
above the upper limit of the 90th percentile of the common
range found in Eastern United States soils. Aluminum,
arsenic, and chromium were also found at elevated
concentrations in all surface soils collected on the Site,
and in one surface soil sample collected downgradient of the
Site.. While these inorganics are important, copper, lead,
and zinc were the focus of the EA because of their toxicity
and elevated concentrations compared to the other
inorganics.
PCBs, especially Arochlor 1260 and 1248, were detected in
soil at concentrations greater than the EPA Region 3 risk-
based concentrations for residential soil. Bis (2-
ethylhexyl) phthalate was detected in 12 of the 17 soil
samples with a maximum concentration of 63,000 ug/Kg.
Eleven of the 12 samples had concentrations significantly
above background levels. PCBs and Bis (2-ethylhexyl)
phthalate were the focus of the EA for organics in soil.
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Based on potential exposure pathways and receptors,
indicator species and assessment endpoints were selected.
Ubiquitous indicator species were chosen based on their •
habitat requirements and the likelihood they would occur on
the Site.
43) The Company Group contends that the RI is inconsistent in
using the arithmetic mean to calculate contaminant
concentrations in the human health assessment and the
geometric mean in the ecological assessment. Rationale for
their use in either case is not explained.
Response: EPA prefers that ecological and human health risk
assessments be based upon the 95% Upper Confidence Limit
(UCL) of the arithmetic mean rather than the geometric mean,
since the arithmetic mean of the appropriate data set is
generally more conservative. The potential for unacceptable
ecological risk was identified for this Site even though the
less conservative geometric mean was used in the ecological
risk assessment.
44) The Company Group contends that the ecological assessment
incorrectly assumes that incidental soil ingestion is 100 %
of the diet and adds this amount to the estimate of total
dietary intake. This effectively doubles the estimate of
food consumed and more importantly would significantly
overestimate risk.
Response: Although the approach used to estimate dietary
exposure to Site contaminants is highly conservative, the
overall conclusions of the ecological assessment are still
valid. Several Site contaminants are highly elevated in
Site soils and a risk to ecological receptors would be found
even if a less conservative approach for estimating dietary
exposure was used, such as assuming that the soil intake was
only 10% of the intake of plant and animal material. (See
response to Comment 46 in this section for Environmental
Effects Quotients, which still show adverse effects to Site
contaminants.)
45) The Company Group stated that the ecological assessment is
incorrect in its assumption that meadow voles consume both
plant and animal matter. Meadow voles are herbivores, as
cited in the reference used in the assessment (Martin et.
al. 1951).
Response: The diet for the meadow vole should have been
100% plant material. The fact that the vole diet used in
the risk assessment was 50% plant material and 50% animal
material (i.e., terrestrial invertebrates) generally results
in a higher and thus more conservative estimate of exposure.
This occurs because the contaminant levels in terrestrial
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invertebrates were assumed to be the same as in soil,
whereas contaminant levels in plants were calculated by
multiplying this contaminant level in soil by a plant uptake
factor that usually was less than 1.0. However, in the case
of zinc, for example, the assumption of a diet of both plant
and animal material results in lower exposure for the vole
than a diet composed entirely of plant material, because the
plant uptake factor for zinc is greater than 1.0 for plant
stems and leaves. Although this assumption affected the
estimated exposure of the vole to Site contaminants, the
overall conclusions of the ecological assessment are valid
(i.e., Site contaminants such as copper are highly elevated
in Site soils and a risk to the vole would have been found
with a diet composed entirely of plants). (Again, please
refer to the Environmental Effects Quotients found in the
response to Comment 46.)
46) The Company Group contends that it is inappropriate to
compare an estimated dose value, as calculated for the green
frog, with National Ambient Water Quality Criteria
concentrations. These concentrations are reported in water
and are reflective of "immersion"-type exposures, not
ingested doses.
Response: Use of the extrapolation of frog ingest ion to
body contact (immersion) exposure is inappropriate in
calculation of a hazard quotient for lead for the green
frog; from an estimated intake in mg/kg/day and a toxicity
endpoint in mg/L determined from an immersion study. These
are two completely incomparable means of exposure.
Consequently, it may not be possible to quantitatively
evaluate potential risk of lead to the green frog, based on
the predicted concentration of lead in its diet. However, a
risk to the green frog is suggested because the average
total lead concentration in surface water from the Site (57
ug/L) is considerably greater than the chronic USEPA Ambient
Water Quality Criteria for lead (3.2 ug/L) (see Table 9-18
in Volume I of the RI Report).
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III. COMMENTS RECEIVED DURING THE COMMENT PERIOD FOR THE REVISED
PROPOSED REMEDIAL ACTION PLAN
EPA Region 3 received several documents and letters
containing comments on the Revised Proposed Remedial Action Plan.
The majority of the comments presented here were submitted by a
group of companies associated with the Site ("Company Group").
The Company Group's comments primarily address components of the
RI/FS Report and Revised Proposed Remedial Action Plan (with
particular focus on the discussion of listed wastes at the Site).
In addition, the Company Group presented a modified remedial
alternative for EPA's consideration. Issues which have been
addressed in the previous Responsiveness Summary Sections are not
repeated here.
1) The Company Group asserted that EPA has not issued any
revisions of the supporting technical documentation (i.e.,
the RI/FS) for public review and comment, therefore making
an examination of the Revised Proposed Remedial Action Plan
difficult. Additionally, the Company Group also stated that
most of their comments on the original proposed plan were
not considered.
Response: The Revised Remedial Action plan was issued based
on the RI/FS and other documentation previously included in
the Administrative Record. Upon further evaluation, EPA
determined that the soil and sediment requiring cleanup
contained a hazardous waste listed under RCRA. Therefore,
off-site disposal of this material was revised in accordance
with RCRA requirements for listed hazardous wastes. These
changes were documented in the Revised Remedial Action Plan.
(EPA reverted to its original position on this issue in the
ROD.) The only other changes presented in the revised plan
were changes in the proposed cleanup levels for the Site.
Again, the basis for these changes were discussed in the
Revised Proposed Remedial Action Plan. Further
documentation of the cleanup level calculations was provided
to the Company Group upon request. EPA's decision not to
make other changes to the proposed alternatives did not
constitute a rejection of comments made by the Company Group
during the first comment period. Those comments have been
fully considered and the ROD reflects many of the
recommendations made by the Company Group.
2) The Company Group stated that no reassessment of the
remedial alternatives was performed despite the significant
changes in cleanup levels and costs.
Response: EPA fully evaluated the revised remedial
alternatives in the Revised Remedial Action Plan in
accordance with the requirements of Section 300.430(e)(9) of
the NCP, 40 C.F.R § 300.430(e)(9).
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The Company Group maintained that EPA's identification of
three of the constituents of concern in the ground water (PCBs, .
beryllium, and manganese) is not supported. Below is a summary
of their concerns on this issue as presented in the comments
submitted in their February 22, 1995 document. These issues are
also revisited and addressed later in discussion of risk
assessment issues.
3) The Company Group expressed concern that EPA identified
PCBs, beryllium, and manganese as contributors to ground
water risk, because these constituents have a substantial
impact (with respect to feasibility and cost) on the
selection of remedy for the Site. This impact on the remedy
is due to the fact that the presumption that PCBs (a
semivolatile organic) and beryllium and manganese
(inorganics) are in the ground water eliminates some ground
water treatment technologies from consideration, and
dictates the use of other technologies that may not be as
effective, or necessary at all, in remediating ground water
at the Site.
Response: EPA agrees that manganese and beryllium are
probably naturally occurring substances in the area.
However, the presence of elevated levels of manganese in
some areas suggests that it may have leached due to the
presence of chlorinated organics.
At the time the Feasibility Study was compiled, these three
constituents were considered to be contaminants of concern
in the selection of remedial alternatives for the Site. The
Agency maintains that PCBs are still considered to be a
possible ground water contaminant, despite the Company
Group's assertions to the contrary. (See response to
comment 5 of this section)
Treatability studies can be performed during the pre-design
phase to identify whether air sparging and soil vapor
extraction can be implemented along with the chosen ground
water pump and treatment technology as an enhancement to the
system. However, the hydrogeology in the area to be
addressed, particularly the shallow water table and clay-
rich soils, may limit the effectiveness of these
technologies at the Site. '~
4) The Company Group suggests that the constituents of concern
be limited to PCBs and metals in soils, and VOCs in ground
water.
Response: The cleanup levels established in Table 12 of the
ROD are consistent with the Company Group suggestion, with
the exception of PCBs in ground water. The issue of
inorganics in ground water is discussed in Comments 7, 12,
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and 14 of this section.
5) Ground water samples were taken subsequent to the Remedial
Investigation by the Company Group. The sample results
indicated that PCBs were not actually present in filtered or
unfiltered ground water samples. The Company Group
concluded that the PCBs found by EPA may have been present
due to well or sample contamination.
Response: There was low level detection of PCBs in ground
water samples collected in some of the monitoring wells
during the Remedial Investigation. The low level detection
of Arochlor 1260 in MW-3D and MW-3B may be due to suspended
soil particles that are contaminated by Arochlor 1260.
However, high concentrations of solvents, such as toluene
(2.5 mg/1) and 2-butanone (21.1 mg/1) that were found in MW-
3D, suggest that the detection of Arochlor 1260 may have
occurred because it was dissolved by, and moved downward
along with, these solvents. Varying PCB detection results
could also be attributable to seasonal fluctuation.
Based on the data collected in the RI, EPA has decided that
it is premature to draw the conclusion that PCBs are not
present in ground water. EPA recommends that additional
sampling be performed during the remedial design phase of
the project to further evaluate this issue.
6) The Company Group noted that since beryllium was found to
occur at high concentrations both upgradient of the Site and
in other wells in the area, the beryllium found at the Site
is naturally occurring.
Response: The Agency agrees with this comment, and
acknowledged this possibility in the FS and the original and
Revised Proposed Remedial Action Plans. EPA Region 3
routinely calculates risk for all contaminants which are
present at levels above risk-based concentrations and/or
ARARs (e.g., MCLs), regardless of whether they are also
found in background wells at the same level. EPA is not
requiring cleanup of the beryllium present in the ground
water because the Agency agrees it appears to be a natural
occurrence. However, beryllium should still be considered
when evaluating the cumulative risk posed by contaminants in
the ground water at the Site.
7) Manganese was also felt by the Company Group to be a
naturally occurring substance at the Site.
Response: EPA agrees that manganese occurs naturally in the
ground water at the Site. However, isolated high levels of
manganese are suspect and may have leached due to the high
levels of solvents present in some areas. The levels of
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manganese are expected to decrease concurrently with
remediation of the chlorinated organics. It should be noted
that manganese is not a hazardous substance under CERCLA and
that manganese at the Site does not contribute significantly
to the risks driving the cleanup.
8) It was requested that ground water in the area of the Site
be classified as a Class III aquifer, and therefore not be
considered as a potential source of drinking water, or be
considered of limited beneficial use since it is
contaminated with naturally occurring constituents. It was
therefore further argued that such a determination would
negate the need for any type of aquifer remediation.
Response: The aquifer at this Site could not be classified
as a Class III aquifer as outlined in the EPA December 1986
Guidelines for Ground-Water Class-ification under the EPA
Ground-Water Protection Strategy. In order to be
classified as a Class III aquifer, any of the following
conditions must be met:
• insufficient yield for an average sized family,
• ground water with a total dissolved-solids (tds)
concentration over 10,000 mg/1, or
• ground water that is "so contaminated by naturally
occurring conditions, or by the effects of broad-scale
human activity (i.e., unrelated to a specific
activity), that they cannot be cleaned up using
treatment methods reasonably employed in public water-
supply systems."
None of the above conditions are present in the aquifer at
the Site. That is, the aquifer at the Site does have
sufficient yield for an average sized family (in fact many
households surrounding the Site use home wells completed in
the aquifer as their only source of water). While some
inorganic constituents were detected and may appear to be
naturally occurring (e.g., iron and, possibly, beryllium),
these could be removed using treatment methods reasonably
employed in public water supply systems. Consequently, the
aquifer at the Site can not be classified as a Class III.
Since all residences immediately surrounding the Site use
private wells as their only source of water, the aquifer at
the Site would be classified, in accordance with EPA
guidance entitled "Guidelines for Ground-Water
Classification Under the EPA Ground-Water Protection
Strategy" [Office of Ground Water Protection Directive No.
WH-550G (December 1986)], as Subclass IIA aquifers.
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RCRA Listed Hazardous Waste Comments
9) The Company Group submitted several comments relating to
EPA's decision, announced in the Revised Proposed Remedial
Action Plan, to consider Site wastes as RCRA listed
hazardous wastes. The Company Group contends that the
evidence does not support such a conclusion, that the
decision to treat the wastes as RCRA listed hazardous wastes
would substantially increase the costs of the remedy while
resulting in no corresponding increase in protectiveness,
and that the decision runs counter to the Agency's goal of
accelerating cleanups and streamlining the Superfund
program. The Company Group further requested that the
Agency identify the areal extent of contamination affected
by RCRA listed hazardous wastes and the category of RCRA
listed hazardous waste EPA believed to be present at the
Site.
Response: Following the careful consideration of comments,
information relating to the source and generation of wastes
found at the Site, and of the implications of this issue on
protection of human health and the environment, EPA has
decided to reverse its proposed view that Site wastes be
handled as RCRA listed hazardous wastes. Rather, Site
wastes will be tested to determine whether they warrant
handling as RCRA characteristic hazardous wastes pursuant to
40 C.F.R. Part 261, Subpart C, and shall be handled
accordingly. The Agency notes that, while not directly
relevant to the issue of whether Site wastes are properly
considered RCRA listed hazardous wastes, the protectiveness
of the remedy is not compromised by this decision.
10) The Company Group stated that the Agency should address the
issue of a soil treatability variance for this Site, as
referenced in the preamble to the NCP.
Response: A treatability variance can be granted by EPA
only after a petitioner has demonstrated that wastes cannot
be treated to meet the applicable treatment standards (40
C.F.R. § 268.44). Without such a demonstration, EPA cannot
comment on a treatability variance for these wastes.
Comments on the Risk Assessment
11) The Company Group stated that exposure concentrations for
many parameters appear to be significantly biased high by
the incorrect use of values substituted for non-detects.
Response: EPA Region 3 acknowledges that there are some
inconsistencies with respect to the use of one-half the
Contract Required Quantitation Limit (CRQL) in the subject
risk assessment with respect to the calculation of the
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concentration term. A review of the methodology used in the
risk assessment, to calculate the concentration term for
vinyl chloride, for example, indicates that all samples with
non-detected levels of vinyl chloride were assumed to have a
contaminant level of zero. In fact, one-half the CRQL was
not used. Therefore, the concentration term may have been
underestimated in some instances. Even with this apparent
underestimation of contaminant levels, there is substantial
risk to warrant cleanup. Note that vinyl chloride was
detected in monitoring well samples at levels up to 32.2 ppb
(Table 5 of the RI Report). These levels exceed the risk-
based concentration for vinyl chloride of 0.02 ppb, the
Maximum Contaminant Level (MCL) of 2 ppb, and the CRQL of 10
ppb. Note that the RI Report does discuss the uncertainty
in the use of the CRQLs and their risk levels. This
information is noted in the Data Validation Section of the
RI Report.
EPA also acknowledges that it is more appropriate to use the
Sample Quantitation Limits (SQLs) than the CRQL in the
calculation of the concentration term for the risk
assessment. While SQLs do take into consideration dilution,
matrix effects, etc., their use was not required at the time
the Site was scoped several years ago. EPA disagrees with
the Company Group's assumption that use of SQLs will result
in a lower concentration term. In some instances, when
there is substantial dilution and/or matrix effects, the
SQLs are much higher than the CRQLs, especially if the
Method Detection Limits used for analyses are high.
Review of Table 3-1 on page 13 of the Company Group's
document (February 1994) illustrates that the contaminants
that pose the most concern in ground water are above their
respective Maximum Contaminant Levels (MCLs) and risk-based
concentrations (RBCs). Therefore, such contaminants should
be carried through as contaminants of concern (COCs). In
addition, their risk level is probably biased low due to the
use of zero for non-detects in calculating the concentration
term..
While the EPA could consider a statistical approach for
determining the concentration below the detection limit for
non-detects, this approach is not necessary since-the
detected levels are much greater than the CRQLs. Also, the
risk levels are above those calculated at the CRQLs.
Since the detected levels are so high, the arguments made
for vinyl chloride and beryllium by the Company Group [such
as the instance where they state that the minimum
concentrations reported for vinyl chloride and beryllium are
below the level assigned to non-detects, in which case it is
estimated that this convention may lead to an overestimate
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of exposure (and risk) by a factor of 5], are not valid.
Note that the uncertainty in the risk estimates is taken
into consideration by presenting the average risk estimates
for each exposure chemical for each exposure route of
concern for all media. The risk summary tables in the
Appendices to the RI Report indicate that the average risk
level for ground water is still of concern for children.
This is despite the elimination of beryllium and manganese
as COCs. The risk is not due to the presence of high levels
of "detectable" contamination at both the average and upper-
bound concentration term estimates.
12) The Company Group stated that the documents reviewed
indicate no scientific evaluation of background
concentrations in the selection of contaminants of concern.
Response: EPA Region 3 has considered a scientific
evaluation of background in the selection of COCs. The
contaminant levels detected on-site for soil were compared
to background levels for inorganics. In cases where the
background levels were higher than the detected levels on-
site, the contaminant was screened out. It was not
considered a COC.
In the case of ground water, background levels of beryllium
and manganese were considered. The EPA has eliminated
beryllium and manganese from the risk assessment as COCs
based on data which indicate that beryllium and manganese
are naturally occurring. The isolated high levels of
manganese are suspect and may have leached due to the high
levels of solvents present in some areas.
Treatment of the ground water to remove beryllium or
manganese is not required in the ROD. Levels of manganese
and beryllium will be monitored during cleanup activities.
The levels present will be considered in evaluating the
overall performance of the ground water treatment system.
13) The Company Group stated that the analysis of uncertainty in
the risk assessment is inadequate for policy and technical
decisions; stating that the uncertainty analysis was
qualitative and incomplete. —
Response: EPA Region 3 did conduct quantitative analysis of
the uncertainty. While this was not done using a Monte
Carlo approach, it was done using a central tendency
approach. The central tendency estimates the average risk
at the Site using an average for the concentration term and
average exposure parameters. All of the assumptions made
and exposure parameters used are in the RI Report. The
Phase I and Phase II data used were previously noted.
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The Company Group asserted that several errors they noted in
the RI/FS and EPA's Revised Proposed Remedial Action Plan have
significant ramifications for risk results or policy decisions.
A report was provided to EPA last year, by the company Group,
during the first public comment period on the original Proposed
Remedial Action Plan (this report has been addressed by the
Agency in the prior section). The Company Group submitted only
selected issues which are summarized below.
14) The Company Group contends that EPA did not characterize
regional background levels of inorganics in subsurface soils
because the 90th percentile values for the eastern U.S., as
reported by USGS, were used as a basis for comparison.
Response: Metals concentrations in soils naturally tend to
be highly variable. Data for a small number of background
soil samples at a site often do not adequately reflect the
range of metals concentrations that could occur naturally,
Therefore, EPA uses values reported by USGS to assist in
evaluating background concentrations of metals at Superfund
sites. By using the 90th percentile values, only 10% of the
naturally occurring concentrations would be expected to
exceed these values. Metals concentrations in site soils
that did not exceed these values were considered within
background concentrations. A soil background sample (SS-7)
and a sediment background sample (SED-16) were collected
during the RI. The metals concentrations in both these
samples were below the upper 90th percentile concentrations.
EPA agrees that additional background sampling may have been
useful at the Site. However, since metals contamination is
not the basis for the cleanup actions selected in the ROD,
further background sampling does not appear warranted.
15) EPA's Revised Proposed Remedial Action Plan states that
beryllium has been associated with carcinogenicity while the
RI states that cancer risk is not clearly associated with
beryllium.
Response: According to IRIS (the Agency's Integrated Risk
Information System), inhalation of high levels of beryllium
is associated with lung cancer in laboratory animals.
However, this issue is moot in as much as beryllium is not
considered to be a site-related COC. —
16) Page 8-12 of the RI/FS states that, because Site
contamination was limited to the bermed area, it was the
area evaluated for exposure. The Risk Assessment Guidance
for Superfund (RAGS), Part B states on page 6-28 that, "in
some cases, contamination may Jbe unevenly distributed across
a site, resulting in hot spots...exposure to the hot spot
should be considered separately." Representative exposure
characterization would identify the hot spot and calculate
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exposure and risk with and without those data, not with
those data alone.
Response: On-site hot spots were considered by performing
separate risk analyses of the Phase I and the Phase I and
Phase II (combined) data. The Phase I data include biased
surface soil samples where hot spots were expected to occur.
The Phase II data contained non-biased random surface and
near-surface soil samples. The Phase I data were combined
with the Phase II data in order to present a complete
picture of the most reasonable risk at the Site for soil.
However, the Phase I data were analyzed separately as well.
In either case, the risk levels calculated were
unacceptable, even when the central tendency estimate was
considered.
17) EPA's Revised Proposed Remedial Action Plan and FS
incorrectly list MCLs for beryllium and vinyl chloride as l
ug/1, rather than 4 and 2 ug/1, respectively.
Response: EPA acknowledges this comment. These errors were
considered in preparing the ROD.
18) The Company Group stated that risks attributable to the Site
have been overestimated by the compounded effect of
questionable methods and assumptions including:
a. use of outdated PCB cancer slope factors,
b. inclusion of beryllium and manganese as Site
contaminants,
c. improper calculation of exposure point
concentrations, and"
d. use of unfiltered, turbid ground water samples.
Response: The Agency has already considered and/or taken
into account points raised in items a through c. The issues
presented in item b are valid and have been previously
addressed in this section. 'With respect to item c, the
Agency had mixed views with respect to the calculation of
exposure point concentrations (see Comments 30 to~33 in
Section II). The Agency does not agree with the conclusion
of the Company Group with respect to item a (see Comment 25
in Section II) since it was pointed out that the difference
in the resulting slope factor is increased by only a factor
of two, which is generally not significant. With respect
to item d, EPA does not routinely sample and analyze
filtered organic samples. This is due to the fact that
organics may be precipitated during preservation and lost in
the filtrate, thereby biasing the concentration for organics
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low.
19) The Company Group recalculated the human health risk
associated with ground water for the Site by eliminating the
risks associated with PCBs, beryllium, and manganese. The
revised risk value was approximately 7.8 x 10" . The
Company Group also recalculated the soil-related risk using
an alternative cancer potency factor for PCBs, weighted for
the relative occurrence of various Arochlors. The revised
risk value was 2.8 x 10"4. The Company Group concluded that
the total baseline risk, from these few revisions, was
approximately half that determined by EPA (1.1 x 10~4) .
The company Group estimated a residual risk associated with
EPA's proposed remedy of 7.4 x 10~4. Therefore, the Company
Group contends that EPA's remedy only achieves marginal risk
reduction.
Response: EPA does not believe that PCBs, beryllium, and
manganese should be eliminated from the overall risk
calculation for ground water at the Site. EPA calculated
the risk for future potential residents using ground water
at the Site to be 1.1 x 10~3 for adults and 5.3 x 10~4 for
children less than 6 years old. Likewise, EPA used current
guidelines for evaluating the risk associated with PCBs in
soil. EPA's risk calculations are 8.3 x 10~4 for adults and
6.0 x 10~4 for children less than 6 years old. EPA has also
calculated the residual risk at the Site, after the remedy
selected in the ROD is implemented, at 5.1 x 10"5.
Even with the assupmtions made by the Company Group, the
risks associated with ground water and soil at the site
exceed 1 x 10~4, which is the level established in the NCP
(40 c.F.R. § 300.430(e)) for triggering action at Superfund
sites. The remedy selected in the ROD reduces the Site
risks to a level that is within the acceptable risk range
(i.e., 1 x 10~4 to 1 x 10~6) and is, therefore, considered
to be effective in protecting human health and the
environment.
Comments on the Feasibility Study
20) The Company Group stated that some on-site treatment
technologies that would appear to have merit were not
identified or were misapplied and, as a result, ruled out.
The example cited was stabilization, which was only
considered in combination with steam stripping. They felt
that stabilization/chemical fixation would seem to be better
applied only to the top six feet of soil in the former burn
pit area and sediments along the intermittent stream where
the constituents of concern are predominately PCBs and
125
-------
metals. With this limitation, the Company Group felt
excavation and above-ground fixation may be more appropriate
than an in-situ technology. They also felt that other
technologies (which they did not mention) could be used to
address the deeper material where the focus is predominately
VOCs. They also stated that air sparging was not identified
to address the soils and shallow ground water impacted by
VOCs.
The Company Group concluded by stating there is no
indication in EPA's Revised Proposed Remedial Action Plan
that these alternatives were considered, and no
justification in the documents publicly available as to why
they were omitted.
*
Response: With respect to the use of stabilization, the FS
(on Page 2-41) ruled out the use of this treatment
alternative where organics-contaminated soil is present. The
Agency is confident that the selected alternative will
effectively address the contamination at the Site in the
most cost effective manner. However, as mentioned earlier,
air sparging and soil vapor extraction can be considered if
pre-design treatability testing shows them to be successful
in addressing conditions on the Site.
The Company Groups Review of EPA's Revised Proposed Remedial
Action Plan
21) The Company Group Stated that EPA misapplied and
misinterpreted the TSCA PCB Spill Policy as an ARAR at the
Site as a result of a statement they referenced from the FS,
page 2-6, which states that the only chemical-specific ARAR
identified for soil remediation identified at the Site is
the TSCA requirement for the remediation of soils
contaminated with PCBs.
In defense of their position, the Company Group referenced a
December 6, 1994 Federal Register notice of a proposed
revision to PCB regulations, and the Guidance on Remedial
Actions for Superfund Sites with PCB Contamination (OSWER
Directive 9355.4-01 (August 1990)), which both indicate that
the TSCA policy is not an ARAR.
Response: The TSCA PCB Spill Cleanup Policy of 1987
requires stringent cleanup of PCBs to different levels
depending upon spill location, the potential for exposure to
residual PCBs, etc. in non-restricted access areas where
there is greater potential for human exposure to spilled
PCBs. Much less stringent requirements apply where there is
little potential for human exposure.
126
-------
Although the 1987 policy was intended to be applicable to
"new" spills of PCBs, the policy has also been used in the
cleanup of historic spills, particularly in the case of
CERCLA remediations (as is the case at this Site).
Since 1990, the Superfund program has adopted an approach to
cleanup of PCBs that relies heavily on the 1987 TSCA policy.
Because the TSCA PCB Spill cleanup Policy is not a binding
regulation, it is not an ARAR for Superfund response
actions. However, as a codified policy reflecting
substantial scientific and technical evaluation, it has been
considered as important guidance in developing cleanup
levels at Superfund sites.
According to the TSCA PCB Spill Policy at 40 C.F.R. §
761.120, it is recommended that, in the case of a future
residential use scenario, PCB spills be cleaned up to less
than 1 ppm on the surface to address threats posed by direct
contact. Where soil with concentrations greater than 1 ppm
is left in place in these cases, the depth of soil cover is
determined by site specific conditions.
In August 1990, EPA issued several CERCLA guidance documents
regarding remediation of PCBs at Superfund sites. Among
other provisions, these guidance documents establish
guidelines for the CERCLA Program to follow in setting
preliminary remediation goals for PCBs for soil, ground
water, and sediment contaminated with PCBs at Superfund
Sites. (See "A Guide on Remedial Actions at Superfund Sites
with PCB Contamination", OSWER Directive No. 9355.4-01 FS
(August 1990)["PCB Guide"].)
22) The Company Group stated that the proposed cleanup levels
for metals and volatiles in ground water are instrument
response levels, not quantification levels, and are not
technologically feasible for compliance determination.
Response: The proposed cleanup' levels for metals and
volatiles in ground water are not instrument response levels
(IRLs). They are minimum levels (MLs) of detection and are
derived based on three times the method detection limit
(MDL). The MDL is defined as the minimum concentration of a
substance that can be measured and reported with-S9%
confidence that the analyte concentration is greater than
zero and is determined from analysis of a sample in a given
matrix containing the analyte. The ML is three times the
MDL. The MLs are more reliable than the MDLs and the IRLs,
and are therefore, appropriate for compliance determination.
23) The Company Group stated that inclusion of manganese as a
contaminant requiring strict cleanup standards is
inconsistent with its status as an essential micronutrient.
127
-------
Response: As previously stated above in comments 7, 12, and
14, manganese is considered to be a naturally occurring
substance and has been eliminated as a COC and is also not
considered to be a hazardous substance. The Company Group
should refer to the IRIS database for further information
regarding the toxicity of manganese. The Reference Dose
(RfD) for manganese for drinking water of 5E-03 mg/kg/day is
based on human chronic ingestion data. There is one
epidemiologic study of manganese in drinking water performed
by Kondakis et al., 1989 (See IRIS database for reference)
which describes toxicologic responses in humans consuming
manganese dissolved in drinking water. A variety of
symptoms were reported including weakness/fatigue, gait
disturbances, tremors, and the lack of muscle tonicity.
24) The Company Group stated the FS and Revised Proposed
Remedial Action Plan do not take into account the residual
risks associated with contaminants remaining after
implementation of the proposed remedy.
Response: The FS contains a qualitative assessment of the
residual risks. A quantitative assessment is attached for
the ground water exposure route. Residual cancer risks for
ground water are estimated to be a total of 5.1E-05. PCBs
contribute the most to this residual risk. A total hazard
index of 0.113 is calculated.
Residual risks for soil were limited to PCBs and lead.
There are no toxicity criteria available for lead. The
residual cancer risk for PCBs at a cleanup level of l ppm is
IE-OS. The total residual cancer risk for soil and ground
water is estimated to be 6.1E-05. The total hazard index is
estimated to be 0.113.
25) The Company Group stated that short-term risks associated
with various remedial alternatives, residual risk, and risk-
based benefits of implementation time are not considered in
this remedy selection.
Response: EPA qualitatively evaluated the short-term risks
associated with all the alternatives in the RI/FS and both
the original and revised Proposed Remedial Action Plans.
EPA also conducted a quantitative evaluation of residual
risk associated with the remedy selected in the ROD as
discussed in the previous comment. The short-term risks
associated with the ROD remedy can be readily controlled. A
quantitative assessment of short-term risks can be performed
as part of the Remedial Design after the detailed
specifications of the control measures have been determined.
26) The Company Group stated that the Proposed Remedial Action
Plan relies too heavily on the preference for the treatment
128
-------
and is directly contrary to the intent of policy makers as
expressed in the remedy selection proposal put forth by EPA
in April 1994 during the reauthorization debate.
Response: The remedial alternative chosen for this Site
consists of off-site disposal of contaminated soil and
sediment in an approved landfill and requires little, if
any, treatment to address soil contamination. Ground water
will be treated to reduce the threat from contamination.
This alternative most effectively addresses all contaminated
matrices while minimizing costs. Other alternatives were
either less expensive but less effective, or more expensive,
but unable to offer a greater degree of protection than the
chosen alternative.
In addition, the proposed bill was not enacted, and is
therefore not relevant to this remedy selection.
27) The Company Group stated that EPA's preferred alternative
involves extensive excavation and disposal of contaminated
soils and sediments. They contend that the risks associated
with the implementation of such large excavation activities
are significant and have not been addressed.
Response: The ROD requires that air monitoring for dust and
Site contaminants be performed during the excavation in
accordance with Federal and state regulations to protect the
health and safety of on-site workers and nearby residents.
The ROD also requires that measures be taken to control
fugitive emissions. Such measures can be readily
implemented to prevent any unacceptable releases of Site
contaminants.
28) The Company Group stated that it is highly unlikely that the
proposed pump and treat technology will be capable of
restoring the shallow ground water aquifer system to
drinking standards due to the local background
concentrations of inorganic compounds. The Company Group
also asserts that localized treatment of beryllium and
manganese in ground water will only cause a temporary
reduction in the presence .of these contaminants since they
are naturally occurring.
Response: The filtered ground water sample at monitoring
well MW-3 is slightly above the drinking water standard for
beryllium. Currently, there is no standard for manganese.
EPA agrees that the levels of beryllium and manganese are
naturally occurring and the remedy selected in the ROD does
not require extraction and treatment of inorganic compounds
in the ground water.
129
-------
29) The Company Group stated that EPA's remedy allows for
institutional controls to be removed at the end of 30 years,
which will cause an increase in the residential exposure
risk to ground water.
Response: Thirty years was a projection of the time it
would take to complete the action (clean-up the aquifer) in
order to estimate the cost of the remedy. Institutional
controls will not be removed until the remedial action is
complete and the performance standards are met.
30) The Company Group claims that prevention of exposure equates
to negation of risk, therefore removal of hot spots followed
by installation of a cap, along with air sparging and
institutional controls, would not only be sufficient to
eliminate risk at the Site, but would be 20 times more
protective of human health.
Response: EPA does not consider preventing exposure to be
equivalent to cleaning up contamination as a method for
eliminating human health and environmental risk at Superfund
sites. By allowing contamination to remain at a site, the
potential for future exposure also remains. Deed
restrictions to prevent use of the property and a soil cover
to prevent direct contact both require perpetual oversight
and maintenance to ensure their effectiveness. In addition,
it may be difficult and costly to implement an air sparging
technology at the Site given the heterogeneous nature of the
aquifer materials, the occurrence of a clay-rich (lower
permeability) layer in the upper portion of the aquifer
underlying the burn pits at this site, and the limited
thickness of a vadose zone. EPA has determined that the
selected remedy provides the best balance among the nine
criteria set forth in the NCP and provides for effective
long-term protection of human health and the environment.
The ROD does provide the opportunity to evaluate (i.e.,
conduct a treatability study) and potentially implement the
air sparging and soil vapor extraction technologies as part
of the selected alternative.
31) The Company Group stated that the cleanup goals for ground
water have been set well below any federal or state drinking
water standard (i.e., ARARs) and are also below any
available detection methods.
Response: The cleanup levels for ground water were set at
the lowest level at which the entire analytical system gives
a recognizable signal and acceptable calibration point using
the methods specified in Table 12 of the ROD. These levels
correspond to a total residual risk of 5.1E-05. If the
cleanup levels specified in ARARs (e.g., MCLs) were merely
attained and not exceeded, the total residual risk would
130
-------
have exceeded the acceptable risk range l.OE-04 to l.OE-06.
32) The Company Group stated that, not only will the ground
water treatment system create a discharge to local surface
waters that will be subject to applicable requirements, but
that the ability to comply with such applicable requirements
has not been demonstrated.
Response: The performance standards in the ROD require that
treated ground water be discharged to the drainage system
downgradient of the bermed disposal area, or be diverted to
the wetlands to minimize impact to the wetlands. The
discharge shall meet the effluent limits and flow rates
established by the VDEQ Water Division in accordance with
Virginia State Water Control Law, Code of Virginia §§ 62.1-
44.2 et sea, and Virginia Pollution Discharge Elimination
System Regulations (VR 680-14-00). EPA does not anticipate
difficulty in achieving the effluent limits to be
established by VDEQ.
33) The Company Group maintained that EPA's preferred
alternative would generate much greater risks, relative to
their proposed remedy, from ground water discharge and
treatment emissions, heavy equipment, and truck traffic
(which would transport contaminated soil to the nearest
acceptable landfill).
•»
Response: The risks inherent in the actual cleanup
activities required for this Site can all be readily
controlled by properly designing and implementing
appropriate precautions. The component of the remedy that
may pose the greatest potential for risk during
implementation is the air sparging and soil vapor extraction
proposed by the Company Group. However, EPA believes that
even these technologies, if properly designed and
implemented, can be used without adverse impact to human
health or the environment.
The Company Group submitted a modified remediation
alternative for EPA's consideration. Although EPA received this
information after the close of the comment period, EPA-reviewed
it carefully. Listed below are the primary components of the
modified alternative and EPA's responses.
34) The Company Group's alternative proposes institutional site
controls, which would limit future use of the burn pit area
to nonresidential uses consistent with the proposed
commercial property cleanup level. These controls consist
of access [deed] restrictions, which would prohibit
residential use of the Site, and installation of a drinking
131
-------
water well at the Site as well. This restricted area is
proposed to cover all contaminated portions of the Site and
a large buffer area.
Response: Institutional controls appear limited to
restrictions on groundwater use and restrictive covenants.
As noted earlier in comment #11 of Section II, EPA does not
believe that reliance on institutional controls to restrict
future use would be appropriate in this case. The land use
currently in the vicinity of the Site is rural residential.
The Hanover County Comprehensive Plan does not propose any
changes in the vicinity of the Site that would attract more
intense residential development (i.e., public sewer and
water); nor does the plan advocate changes that would
discourage continued construction of rural single-family
homes (i.e., targeted future commercial or industrial use).
There are currently residential properties adjacent to the
Site, including a newly constructed home along the Site
access road. Several potential residents interested in
building homes in the area indicated their concern regarding
property value during the public meeting. Land use
restrictions based on an incomplete cleanup would
permanently reduce the options available for future use of
the property. Use of such restrictions would additionally
run counter to the statutory preference for reducing
volume/toxicity of hazardous substances through treatment.
35) The Company Group's modified alternative would require that
hot spot soils and sediments in the unsaturated zone with
concentrations exceeding [The Company Group's] Site cleanup
goals for subsurface soils or sediments be excavated.
Excavation would include contaminated areas within the
bermed disposal area, as well as in the ephemeral stream.
All soils within the unsaturated zone with concentrations in
excess of EPA's proposed cleanup goal of 400 mg/Kg for lead
would be removed. All soils in the unsaturated zone with
PCB concentrations greater than 10 mg/Kg would be removed.
All sediments with concentrations in excess of EPA's
proposed cleanup goals for protection of ecological
receptors (PCB's >1 mg/Kg, lead >200 mg/Kg, and copper >34
mg/Kg) would also be removed and then consolidated beneath a
cap in the former burn pit area.
Based on existing analytical data, the Company Group
estimates that approximately 2,850 in-place (bank) cubic
yards of soil and 370 cubic yards of sediment require
excavation and disposal. These soil volumes include the top
six (6) feet of soils located in hot spots at the Site and
all of the sediments identified as having lead
concentrations greater than 400 mg/Kg and PCB concentrations
above 10 mg/Kg.
132
-------
Response: The selected remedy differs from that of the
Company Group, with respect to soil excavation and disposal,
particularly since it calls for excavation of PCBs down to l
rag/Kg, and requires that all excavated soils be disposed of
offsite. EPA has determined that PCB-contaminated soils
should be cleaned up to a level of 1 mg/Kg down to a depth
of six feet in order to be protective of human health. This
reflects EPA's residential use assumption. The Company
Group assumed an industrial use scenario for the site. The
Agency believes that application of the residential use
assumption is appropriate in this instance and is consistent
with newly issued guidance entitled "Land Use in the CERCLA
Remedy Selection Process" [OSWER Directive No. 9355.7-04
(May 25, 1995)].
•
36) The Company Group proposes covering any surficial soils
beyond the bermed former burn pit area that have contaminant
concentrations in excess of the applicable Site cleanup
goals. Sediments above acceptable levels will be used as
backfill in the former bermed burn pit area. A soil cover
(incorrectly referred to as a "cap" by the Company Group)
would then be placed over the bermed area to provide a
physical barrier to prevent physical contact with the
underlying soil and to prevent transport of soil from the
Site via stormwater runoff or wind erosion.
The Company Group cited two other Superfund sites in EPA
Region 3, C&R Battery and L.A. Clarke, where this approach
was used.
Response: The Company Group's proposal would allow
contaminants to remain on-site above health-based cleanup
levels. Although the soil cover would prevent direct
contact and the potential spread of contamination via
surface water runoff, future use of the Site would be
inhibited and protectiveness would rely heavily on land use
controls preventing excavation. EPA believes the selected
remedy provides a substantially greater benefit to the
community at a reasonable cost by removing the contamination
and ultimately allowing for unlimited future use.
The examples cited by the Company Group are distinguishable
from this Site. The cleanup at the C&R Battery Site
required excavation, onsite stabilization, and offsite
disposal of over 11,000 cubic yards of lead-contaminated
soil. The only soils that were allowed to be covered were
found on the adjacent property, an active commercial
facility. The C&R Battery Site and the L.A. Clark Site are
both located in historically industrial use areas. The L.A.
Clark Site is bisected by a railroad, thereby making
residential use all but impossible. Yet even at the L.A.
Clark Site, the required cleanup involves treatment of the
133
-------
contaminated soil prior to allowing the placement of one
foot of clean fill.
EPA Alternative B, which examined capping soils and
sediment, required additional sampling to determine the
exact limits of excavation. The Company Group's proposal
did not indicate that additional sampling would take place.
Alternative B of the ROD stated that direct contact with
contaminated soil and sediment would be eliminated by the
installation of a RCRA Subtitle C multi-layer cap. The
Company Group's alternative proposed a cap consisting of at
least one foot of clean fill with a revegetated surface.
This method would be less protective of environmental
receptors than a RCRA Subtitle C cap because it would not
prevent infiltration of surface water and continued
migration of contaminants. Continued implementation of
groundwater treatment would be required to provide long-term
effectiveness. The most effective long-term alternative
would remove Site contaminants through excavation and
disposal of contaminants off-site.
Finally, there is no provision for sampling and analysis of
soil either before or after excavation in the Company
Group's alternative (to determine the full extent of
contamination) and following excavation (to confirm that
cleanup concentrations have been achieved).
37) The Company Group's alternative proposed treatment of ground
water via air sparging/vapor extraction to remove volatiles.
Response: The selected remedy allows for the use of an air
sparging and soil vapor extraction system to attempt to
enhance the operation of the ground water treatment system
if a treatability study-performed during the Remedial Design
demonstrates that these technologies can address Site-
related contaminants in an effective manner. Air sparging
would have to be implemented in combination with soil vapor
extraction and ground water extraction and treatment to
avoid simply transferring contaminants from one media to
another or causing ground water contamination to further
migrate. EPA does not believe that the use of air sparging
can replace the need for ground water extraction and
treatment. The Company Group's document states that air
sparging is as effective as pump and treat in the
remediation of dissolved contaminants. However, it may be
difficult and costly to implement an air sparging technology
at this Site given the heterogeneous nature of the aquifer
underlying the burn pits at this Site and the limited
thickness of a vadose zone.
The selected remedy accommodates these additional
technologies to accelerate the removal of contamination from
134
-------
the groundwater and saturated soils, which would reduce the
need for long-term operation of the ground water treatment
system. Additionally, the ROD clearly states that the use
of these additional technologies cannot interfere with the
implementation of other required components of the chosen
remedy.
General Comments
38) The Company Group requested that comments distributed at a
meeting held in the Region 3 Office on 2/15/95 be made part
of the Administrative Record.
Response: These comments will be placed in the
Administrative Record.
39) The Agency was asked to revisit comments on the risk
assessment that were submitted in February 1994.
Response: These comments were thoroughly addressed by the
Agency after the first comment period. These
comments/responses can be found in Section II of the
Responsiveness Summary.
40) It was stated that preference should be given to
alternatives that can be implemented quickly, bring the Site
to an acceptable permanent risk level with remedial work
that is of the shortest possible duration, will not result
in potentially hazardous discharges to the creek, and will
limit truck traffic and the threat of possible spillage of
contaminated materials on public highways.
Response: The alternative chosen by the Agency has been
screened against the criteria set forth at 40 C.F.R. §
300.430(e)(9)(iii) (see Section IX of the ROD "Comparison of
Alternatives"), which is used for all potential remedial
actions examined at Superfund sites. EPA has determined
that,, of the available options, the selected remedy embodies
the best combination of actions to effectively protect human
health and the environment.
135
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APPENDIX A
Administrative Record Index
The index can be found in the beginning of Volume I of the
H & H Burn Pit Administrative Record File.
A8302679
-------
APPENDIX B
Ground Water Cleanup Level Risk Calculations
-------
-H tnt HBun Pii By »V») liny
Oonrnkin MbWta MM
Nonmw
2-Ounnon* y 2«7t-oi
CJnMr
VtiylCHorW*
Bup -«ttoro*ffiy|*ffw
ftoctof 12«
Iterem
1 2~OlcNonMVw
U-DcNODMhm
1 7IE-OJ
2ME-OJ
OOOE-0)
Total** "" '
ROD
; •
DP*
OMa a^iieti
eooc-oi
1 71E-01
2*
se-oi
• ooE-oa
100C-OI
t.tQC+00
200E-02
»tOE-02
n«e-oi
1.M+00
i ioc«oa
7.roc*oo
t.toc-oa
•.IOE-W
• OOE-01
mKnmicw) OMmpLnMlfemB) MOL QimtpLivrito MMMdn>a«H) eitaci>~
« Ot»M>l«wlbM tiMMbn ni««bi*, on tax* «n> not tcUMd kKwdvlwttinalihcclMnfi IwA
Note: (Mio«ti*««n«lornon-voWll«conUn*Mrt««t«b«»donlno«i4on«nl»
Nato. Io«Nyu««liiMr>«uMn4«d«intar«*nV«>k«MWIonla«;llynMrt*MkittwReCT«bl>tthrlop<«>l|
NDM l «i» AR»H tai »coc»«m >!««»•» «<«n Hurt* -btirtclniMi !•»«!. »i«Amm«t»cli«i4Jl»^t 1h«l«wklDr«in«canumtuniiin«y«liMityb«*io«clMni<>lwM
-------
H&H Burn Pit Superfund Site
Reference doses and carcinogenic potency slope factors.
Groundwater—Cleanup Levels
Oral Inhaled
; :: Inhaled Slope Slope
QralRfD RfD -Factor Factor
Contaminant mg/kg/d mg/kg/d te*ti/m& kg«d/mg
PCBs
Bis(2-chbroethyl)ether
1,1-DCE
Vinyl Chloride
1,2-Dichloroethane
Benzene
2-Butonone
9.00E-03
6.XE-01
2.86E-03
1.71E-03
2.86E-01
7.70E-HOO
1.10E+00
6.00E-01
1.90E+00
9.10E-02
2.90E-02
1.16E4-00
1.75E-01
3.XE-01
9.10E-02
2.90E-02
-------
H&H Burn Pit Superfund Site
Adult resident drinking water ingestion.
Concentration
ingestion rate
Exposure frequency
Exposure duration
Body weight
Averaging time care.
Averaging time ncarc.
Intake (mg/kg-day) =
Contaminant
PCBs
Bis(2-chloroetnyl) ether
1,1-DCE
Vinyl Chloride
1,2-Dichloroethane
Benzene
2-Butonone
Total
mg/L
Ud
d/y
y
kg
d
d
CW
2IR
350 EF
24 ED
70 BW
25550 AT
8760 AT
CWxIRxEFxED
BW
ML*
Cone.
mg/L
2.00E-04
6.00E-05
1.00E-05
3.00E-05
1.00E-05
6.00E-05
6.40E-01
xAT
Lifetime;
Average Chronic
Daily Daily
Dose Dose
mg/kg/d: mg/kg/d
1.88E-06 5.48E-06
5.64E-07 1.64E-06
9.39E-08 2.74E-07
2.82E-07 8.22E-07
9.39E-08 2.74E-07
5.64E-07 1.64E-06
6.01E-03 1.75E-02
• -
Ufettme
Cancer
Risk
1.45E-05
6.20E-07
S.64E-08
5.35E-07
8.55E-09
1.63E-08
1.57E-05
Systemic
Hazard
Quotient
__
—
3.04E-05
—
—
—
2.92E-02
2.93E-02
•ML -Minimum [jtutt—lo»»««t **t «t whicti« eetmmlramemn mccuiB«t» t» dirtacad.
None Th«eono«raBflontar2-butono>«uMdin«woMeulMlonl*l/3orth«tBWhatfdlndB«er
.2-butoion»«nd i.i-DCE.
-------
H&H Burn Pit Superfund Site
Child resident drinking water ingestion.
Concentration
ingestion rate
Exposure frequency
Exposure duration
Body weight
Averaging time care.
Averaging time ncarc.
Intake (mg/kg-day) =
Contaminant
PCBs
Bis(2-chloroethyl) ether
1.1-DCE
Vinyl Chloride
1,2-Dichloroethane
Benzene
2-Butonone
Total ; - ;
•M. -Minimum LtMl--lowMt »wl
Note Th« concantaBcn la 2-Buto
mg/L
Ud
d/y
y
Kg
d
d
CW x IR x
BW
ML*
Cone.
mg/L
2.00E-04
6.00E-05
1.00E-05
3.00E-05
1.00E-05
6.00E-05
6.40E-01
CW
1 IR
350 EF
6 ED
15BW
25550 AT
21 90 AT
EFxED
xAT
Lifetime
Average Chronic
Dally Daily
Dose Dose
mg/kg/d mg/kg/d
1.10E-06 1.28E-05
3.29E-07 3.84E-06
5.48E-08 6.39E-07
1.64E-07 1.92E-06
5.48E-08 6.39E-07
3.29E-07 3.84E-06
3.51E-03 4.09E-02
Ufetima
Cancer
Risk
8.44E-06
3.62E-07
3.29E-08
3.12E-07
4.99E-09
9.53E-09
-— •
9.16E-06
Systemic
Hazard
Quotient
_ ^
--
7.10E-05
—
__
--
6 82E-02
6.83E-Q2
M which • camm inant an •ccwtty b* dracM.
nor* MM in tM aleuHflen !• 1/3 e( «• »«l rmrd indn «of non-«ne«r Mica «« n*r M eonottuad dy taraww, 2 -butonon* and i . i - OCE.
-------
H&HBurnPRSuMrfuntfSat
Adult nddcm ihomrlna, apotm eoncwrtntion*.
. CCB
G-pn«MU. M2O
W«t«rvt«c. «20C
Wat»f vtoc. «t 45C
ShovMTMrno
Droplet divnMir
Drop *"•
Snow*r(towrm»
Showw »t»U velum*
Showtr durcdon
Air *ic lung* rat*
cnvh 20
cm* 3000
cp 1.002
cp 0.588
K 318
rrm 1
3 2
Utain 20
m3 2.80E-HM
mln 1.206+01
mln-1 0.0100007 (RANGE S TO 1.3 PEfl HOUR)
Mt* • '' M»wy'«:.
Omtf.
Timn».
CotO.
Cone.
voe
Tnm.
H20
Air
Cone.
•tSnow Cone.
PC8a
1.1 -oce
Vinyl Chbrie*
2-Sutonon»
Cone.
2.006-04
8.006 -08
1. 006-08
3.006-03
1.006-05
8.006-06
8.406-01
Met Wt
3.286+02
1.436+02
8.706+01
8.306+01
8.906+01
7.806+01
7.206+01
ConMnt
1.076-03
1.316-08
3.406-03
8.186-02
8.786-04
5.506-03
2.746-06
KJ
cnrfv
7.336+00
I.116+O1
1.336+01
1.876+01
1.336+01
1.506+01
1.506+01
KO
7.036 +02
1.006+03
1.296+00
1.806+03
1.286+03
1.446+00
1.506+03
KL
5.946+00
S.52E-01
1.346+01
1.87E+01
1.086+01
1.446+01
1.546+00
7.966+00
7.396-01
1.796+01
£236+01
1.426+01
1.936+01
Z07E+00
Cwd
mg/ r
4086-08
1.406-00
4.306-08
1.576-03
3.786-08
2.046-06
4586-02
3
3.216-04
1.016-06
3.106-03
1.096-04
2.806 -OS
1.806-04
2.946-01
End
3.496-03
1.106-04
3.376-04
1.186 -OS
2.836-04
2.136-03
3.206+00
InSnoww
1.806-03
9.806-08
1.746-04
8.106-O4
1.486-04
1.106-03
1.8S6+00
-------
H&H Bum Pit Supertund Site
Adult resident showering inhalation.
Concentration
inhalation rate
Exposure frequency
Exposure duration
Body weight
Averaging time care.
Averaging time ncarc.
Shower duration
Intake (mg/kg-day) »
Contaminant
PCBs
Bis(2-chloroethyl) ether
1,1 -DCE
Vinyl Chloride
1,2-Dichloroethane
Benzene
2-Butonone
Total
r»- notappflabto
mg/m3
m3/min
d/y
y
kg
d
d
min/d
CA x IR x ET
BWx
•'• '.-.,.• ML*
Cone.
mg/m3
1.80E-03
5.66E-05
1.74E-04
6.10E-04
1.46E-04
1.10E-03
1.65E-I-00
CA
0.0138889 IR
350 EF
24 ED
70 BW
25550 AT
8760 AT
12 ET
xEFxED
AT
Lifetime-
Average Chronic
Dally Daily
Dose Dose
mg/kg/d mg/kg/d
1.41E-06 4.12E-06 •
4.43E-08 1.29E-07
1.36E-07 3.98E-07
4.786-07 1.39E-06
1.15E-07 3.34E-07
8.62E-07 2.51 E -06
1.29E-03 3.77E-03
Lifetime
Cancer
Risk
•••
5.14E-08
2.39E-08
1.43E-07
1.04E-08
2.50E-08
--
2.54E-07
Systemic
Hazard
Quotient
— — • "
— —
__
— —
1.17E-04
1.47E-03
1.32E-02
1.48E-02
"•n InMtoflontodcttycffi** is notMlfcto*
-------
H&H Bum Pit Superfund Site
Child resident drinking water dermal contact
Concentration mg/L
Surface area cm3
Exposure frequency d/y
Exposure duration y
Body weight kg
Averaging time care. d
Averaging time ncarc. d
Bath duration h/d
Conversion Factor l/cm3
DermaJ Permeability Constant cm/hr
(chemical specific)
Absorbed Dose (mg/kg-day) =
CW
7200 SA
350 EF
6 ED
15 BW
25550 AT
2190 AT
0.33 ET
1.00E-03 CF
PC
CWxSAxPCxETxEFxEDxCF
BWxAT '
Contaminant
ML*
Cone.
mg/t
Lifetime
Average
Dafly
Dose
mg/Jcg/d;
Chronic
Daily
Dose
mg/kg/d
Lifetime:
Cancer
Risk
Dermal
Systemic Permeab.
Hazard CoefL*
Quotient cm/h
PCBs
Bis(2-chloroethyl)ether
1,1 -DCE
Vinyl Chloride
1,2-Dichloroethane
Benzene
2-Butonone
Total
2.00E-04
6.00E-05
1.00E-05
3.00E-05
1.00E-OS
6.00E-05
6.40E-01
3.38E-06
1.64E-09
Z08E-09
Z85E-09
6.90E-10
7.81 E-08
4.17E-05
3.95E-05
1.91E-08
Z43E-08
3.33E-08
8.05E-09
9.11E-07
4.86E-04
2.61 E -05
1.80E-09
1.25E-09
5.42E-09
6.28E-11
2.27E-09
—
2.61E-05
--
--
Z70E-06
--
— —
— —
8.10E-04
8.13E-04
1.30E+00"
Z10E-03
1.60E-02
7.30E-03
5.30E-03
1.00E-01
5.00E-03
•ML-Mlrtmum lirfU—lo
Now: Th« cano* noetofl fv 2-bum* en* iinninttn iiri*aiiin '• 1/9 e> tMUM luard index tar nen
"Not*: Kp vHtw for PC8 -
-------
H & H Burn Pit Superfund Site
Groundwater Cleanup Levels*
Cancer Risk Hazard Index
Adult resident drinking water ingestion. 1.57E-05 2.93E-02
Child resident drinking water ingestion. 9.16E-06 6.83E-02
Adult resident showering inhalation. 2.54E-07 1.48E-02
Child resident drinking water dermal contact 2.61 E-05 8.13E-04
Total Risfc 5.12E-05 1.13E-01
•Total Risk for Cleanup levels bated on the Minimum Lsvtl of Detection except for2-butonone which • based on the Risk-Based Concentre
The Minrnum Level of Detection for 2-butonone «1 ppb. .
-------
APPENDIX C
Glossary of Superfund Terms
-------
GLOSSARY
of Superfund Terms
This glossary defines terms often used by the U.S. Environmental
Protection Agency (EPA) staff when describing activities under the
Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA, commonly called Superfund), as amended in 1986. The
definitions apply specifically to the Superfund program and may have
other meanings when used in different circumstances. Underlined words
included in various definitions are defined separately in the glossary.
Administrative Record: A file which is maintained and contains
all information used by the lead agency to make its decision on the
selection of a response action under CERCLA. This file is to be available
for public review and a copy is to be established at or near the site,
usually at one of the information repositories. Also, a duplicate
file is held in a central location, such as a Regional or State office.
Air Stripping: A treatment system that removes, or "strips,"
volatile organic compounds from contaminated around water or surface
water by forcing an airstream through the water and causing the compounds
to evaporate.
Aquifer: An underground rock formation composed of materials
such as sand, soil, or gravel that can store and supply ground water
to wells and springs. Most aquifers used .in the United States are
within a thousand feet of the earth's surface.
Carcinogen: A substance that causes cancer.
Carbon Adsorption: A treatment system where contaminants are
removed from around water or surface water when the water is forced
through tanks containing activated carbon, a specially treated material
that attracts the contaminants.
Cleanup: Actions taken to deal with a release or threatened
release of hazardous substances that could affect public health and/or
the environment. The term "cleanup" is often used broadly to describe
various response actions or phases of remedial responses such as the
remedial investigation/ feasibility study.
Comment Period: A time period during which the public can review
and comment on various documents and EPA actions. For example, a
comment period is provided when EPA proposes to add sites to the National
Priorities List. Also, a minimum 3-week comment period is held to
allow community members to review and comment on a draft RI/FS and
proposed plan.
Community Relations (CR): EPA's program to inform and involve
the public in the Superfund process and respond to community concerns.
-------
Comprehensive Environmental Response/ Compensation, and Liability
Act (CERCLA): A federal law passed in 1980 and modified in 1986 by
the Superfund Amendments and Reauthorization Act. The Acts created
a special tax that goes into a Trust Fund, commonly known as Superfund.
to investigate and clean up abandoned or uncontrolled hazardous waste
sites. Under the program, EPA can either:
o Pay for site cleanup when parties responsible for the
contamination cannot be located or are unwilling or
unable to perform the work; or
o Take legal action to force parties responsible for
site contamination to clean up the site or pay back
the Federal government for the cost of the cleanup.
Cost-Effective Alternative: The cleanup alternative selected
for a site on the National Priorities List based on technical feasibility,
permanence, reliability, and cost. The selected alternative does
not require EPA to choose the least expensive alternative. It requires
that if there are several cleanup alternatives available that deal
effectively with the problems at a site, EPA must choose the remedy
on the basis of permanence, reliability, arid cost.
Emergency: Those releases or threats of releases requiring initiation
of on-site activity within hours of the lead agency's determination
that a removal action is appropriate.
Enforcement: EPA's efforts, through legal action if necessary,
to force potentially responsible parties to perform or pay for a Superfund
site cleanup.
Feasibility Study (PS): See Remedial Investigation/Feasibility
Study.
Ground Water: Water found beneath the earth's surface that fills
pores between materials such as sand, soil, or gravel. In aquifers
ground water occurs in sufficient quantities that it can be used for
drinking water, irrigation and other purposes.
Hazard Ranking System (HRS): A scoring system used to evaluate
potential relative risks to public health and the environment from
releases or threatened releases of hazardous substances. EPA and
States use the HRS to calculate a site score, from 0 to 100, based
on the actual or potential release of hazardous substances from a
site through air, surface water, or around water to affect people.
This score is the primary factor used to decide if a hazardous waste
site should be placed on the National Priorities List.
Hazardous Substance: Any material that poses a threat to public
health and/or the environment. Typical hazardous substances are materials
that are toxic, corrosive, ignitable, explosive, or chemically reactive.
-------
Hydrology: The science dealing with the properties, movement,
and effects of water on the earth's surface, in the soil and rocks
below, and in the atmosphere.
Incineration: Burning of certain types of solid, liquid, or
gaseous materials under controlled conditions to destroy hazardous
waste.
Information Repository: A file containing current information,
technical reports, and reference documents regarding a Super fund site.
The information repository is usually located in a public building
that is convenient for local residents — such as a public school,
city hall, or library..
Leachate: A contaminated liquid resulting when water percolates,
or trickles, through waste materials and collects components of those
wastes. Leaching may occur at landfills and may result in hazardous
substances entering soil, surface water, or around water.
Monitoring wells: Special wells drilled at specific locations
on or off a hazardous waste site where ground water can be sampled
at selected depths and studied to determine such things as the direction
in which ground water flows and the types and amounts of contaminants
present.
National Oil and Hazardous Substances Pollution Contingency
Plan (NCP): The Federal regulation that guides the Superfund program.
National Priorities List (NPL): EPA's list of the most serious
uncontrolled or abandoned hazardous waste sites identified for possible
long-term remedial response using money from the Trust Fund. The
list is based primarily on the score a site receives on the Hazard
Ranking; System (HRS) . EPA is required to update the NPL at least
once a year.
Operation and Maintenance (O&M): Activities conducted at a
site after a response action occurs, to ensure that the cleanup or
containment system is functioning properly.
Parts Per Billion (ppb) /Parts per Million (ppm): Units commonly
used to express low concentrations of contaminants. For example,
1 ounce of trichloroethylene (TCE) in 1 million ounces _of water is
1 ppm; 1 ounce of TCE .in 1 billion ounces of water is 1 ppb. If one
drop of TCE is mixed in a competition-size swimming pool, the water
will contain about 1 ppb of TCE.
Potentially Responsible Party (PRP): An individual (s) or company (ies)
(such as owners, operators, transporters, or generators) potentially
responsible for, or contributing to, the contamination problems at
a Superfund site. Whenever possible, EPA requires PRPs, through administrative
and legal actions, to clean up hazardous waste sites they have contaminated.
-------
Preliminary Assessment: The process of collecting and reviewing
available information about a known or suspected hazardous waste site
or release. EPA or States use this information to determine if the
site requires further study. If further study is needed, a site inspection
is undertaken.
Proposed Plan: A public participation requirement of SARA in
which EPA summarizes for the public the preferred cleanup strategy,
the rationale for the preference, reviews the alternatives presented
in the detailed analysis of the remedial investigation/feasibility
study. and presents any waivers to cleanup standards of §121(d)(4)
may be proposed. This may be prepared either as a fact sheet or as
a separate document. In either case, it must actively solicit public
review and comment on all alternatives under Agency
consideration.
Record of Decision (ROD): A public document that explains which
cleanup alternative(s) will be used at National Priorities List sites.
The record of decision is based on information and technical analysis
generated during the remedial investigation/feasibility study and
consideration of public comments and community concerns.
Remedial Action (RA): The actual construction or implementation
phase that follows the remedial design of the selected cleanup alternative
at a site on the National Priorities List.
Remedial Design (RD): An engineering phase that follows the
record of decision when technical drawings and specifications are
developed for the subsequent remedial action at a site on the National
Priorities List.
Remedial Investigation/Feasibility Study: Investigative and
analytical studies usually performed at the same time in an interactive,
iterative process, and together referred to as the "RI/FS." They
are intended to:
o Gather the data necessary to determine the type and
extent of contamination at a Superfund site;
o Establish criteria for cleaning up the site;
o Identify and screen cleanup alternatives for remedial
action; and
o Analyze in detail the technology and costs of the
alternatives.
Remedial Project Manager (RPM): The EPA or State official responsible
for overseeing remedial response activities.
Remedial Response: A long-term action that stops or substantially
reduces a release or threatened release of hazardous substances that
is serious, but does not pose an immediate threat to public health
and/or the environment.
-------
Resource Conservation and Recovery Act (RCRA): A Federal law
that established a regulatory system to track hazardous substances
from the time of generation to disposal. The law requires safe' and
secure procedures to be used in treating, transporting, storing, and
disposing of hazardous substances. RCRA is designed to prevent new,
uncontrolled hazardous waste sites.
Response Action: A CERCLA-authorized action at a Superfund site
involving either a short-term removal action or a long-term remedial
response that may include, but is not limited to, the following activities:
o Removing hazardous materials from a site to an EPA.
approved, licensed hazardous waste facility for
treatment, containment, or destruction.
o Containing the waste safely on-site to eliminate
further problems.
o Destroying or treating the waste on-site using
incineration or other technologies.
o Identifying and removing the source of around water
contamination and halting further movement of the
contaminants.
Responsiveness Summary: A summary of oral and/or written public
comments received by EPA during a comment period on key EPA documents,
and EPA's responses to "those comments. The responsiveness summary
is a key part of the ROD, highlighting community concerns for EPA
decision-makers.
Site Inspection (SI): A technical phase that follows a preliminary
assessment designed to collect more extensive information on a hazardous
waste site. The information is used to score the site with the Hazard
Ranking System to determine whether response action is needed.
Superfund: The common name used for the Comprehensive Environmental
Response. Compensation, and Liability Act, also referred to as the
Trust Fund.
Superfund Amendments and Reauthorization Act (SARA): Modifications
to CERCLA enacted on October 17, 1986.
Surface Water: Bodies of water that are above ground, such as
rivers, lakes, and streams.
Volatile Organic Compound: An organic (carbon-containing) compound
that evaporates (volatizes) readily at room temperature.
------- |