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Appendix C
Details of Cost Analysis
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OSWER Directive 9835.13
Appendix C comprises six graphs which illustrates the costs of the
RODs reviewed for the comparative analysis, including mean costs,
standard deviations, costs by site type, and costs by site type by
RI/FS and RD/RA lead.
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Appendix D
Summary Comparisons of Sites in
Four Site Categories
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OSWER Directive 9835.13
This appendix contains summary descriptions of the sites whose
characteristics and remedies were compared for the Paired Analysis.
Each site in the four site type categories is discussed in terms
of site characteristics, baseline risk assessment, remediation
goals, remedy selected, treatment versus containment, and
involvement and/or influence of potentially responsible parties and
others.
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OSWER Directive 9835.13
PAIRED ANALYSIS SUMMARY: LANDFILL (Industrial) SITES
The independent selection panel, choose four (4) sites for the
paired analysis in the landfill category.
SITE DESCRIPTIONS
Site A RI/FS Lead - Fund Planned RD/RA Lead - Fund
Site Description: Site A is approximately 1 acre in size and
approximately 20 feet deep. This site was initially operated as
a sand and gravel quarry which was subsequently filled with
hazardous and non-hazardous wastes. It is located in a rural
recreational use area; residences are located nearby. Bulk and
drummed wastes disposed at this site include oily wastes, solvents,
toluene-diisocyanate residue, and other hazardous and non-hazardous
wastes. Approximately 25,000 to 35,000 cu yd of hazardous waste
and contaminated soils are present at this site. Residents within
1/2 mile of the site use ground water for drinking. Ground water
in the source area at this site is also contaminated; however
contamination from the source area has not yet been found in the
nearby residential wells.
Remedy Selected: Major components of the selected remedy include
the following: Excavation and incineration of waste and
contaminated soils; disposal of treated material by backfilling it
on-site; ground water collection and treatment; and deed
restrictions to prohibit installation of drinking-water wells in
the contaminated plume until cleanup goals are met.
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OSWER Directive 9835.13
Site B RI/FS Lead - Fund Planned RD/RA Lead - FRP
Site Description: Site B is an inactive chemical and industrial
waste disposal site approximately 17 acres in size. It is located
in an area of mixed industrial, commercial, and residential use.
Nine acres of this site are highly contaminated. Bulk and drummed
wastes disposed at this site include waste oils, paint solvent,
resins, acids, and a variety of other hazardous and non-hazardous
wastes. Approximately 100,000 cu yd of waste material is present
at this site, 36,000 cu yd of which is highly contaminated. Due
to the high water table the buried wastes are in contact with
ground water. Ground water at this site is highly contaminated.
There is an oil layer floating on top of the ground water
approximately 5 feet below the ground. A previous operable unit
ROD (OU1) addresses the floating oil layer. Approximately 1/4 mile
from this site there is another superfund site which is believed
to have added to the ground water contamination at this site. In
addition, ground water contamination at this site is complicated
by high dissolved solids from a nearby highway maintenance salt
storage facility. Residents near the site use ground water for
drinking; however, none of the ground water wells are currently
contaminated.
Remedy Selected: Major components of selected remedy include the
following: Low-temperature thermal treatment of highly
contaminated soils (hot spots); RCRA Subtitle C cap over the other
contaminated soils; ground water pump and treat; reinjection of
treated water to promote flushing; deed restrictions to prohibit
use of ground water under the site and to protect cap.
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OSWER Directive 9835.13
Site C RI/FS Lead - Fund Planned RD/RA Lead - PRP
Site Description: This site is located on approximately 65 acres
of county-owned land. Site C is located in a mixed agricultural,
residential, and industrial use area. The site consists of the
incinerator building and adjacent property. Areas addressed in the
ROD include a former scrubber wastewater lagoon, an ash disposal
pit, aji ash pile, liquid disposal area and trench, and fill
landfill areas. This site is currently operating as a waste
transfer station. Different areas of this site have received
different type of wastes. Two very large areas of this site have
received mainly municipal wastes (trench and fill landfill areas),
therefore Site C has now been categorized as a municipal landfill.
Liquid hazardous wastes were disposed in one relatively small area
of this site. This portion of Site C, which has characteristics
similar to the other industrial landfill sites evaluated in this
category, will be the focus of comparison. The liquid disposal
area is believed to be the principal source of ground water
contamination at this site. Ground water contamination from this
site has affected the drinking water wells at residences and
businesses near this site. The process of implementing an
alternate water supply for the residences and business affected is
underway.
Remedy Selected: Major components of the selected remedy for the
liquid disposal area include the following: Soil vapor extraction;
vapor phase carbon treatment; ground water pump and treat; closure
with a RCRA Subtitle C cap; and deed restrictions to protect the
cap and use of contaminated ground water.
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OSWER Directive 9835.13
Site D RI/F8 Lead - PRP Planned RD/RA Lead - PRP
Site Description: Site D is approximately 3 acres in size and
approximately 45 feet deep. This landfill is located in a remote
area of mixed industrial and rural residential use. It was
permitted for the disposal of dry, non-hazardous industrial waste.
A predominant feature of this site is its rugged topography with
high relief. The surface of the landfill is capped with silty
clays, sand, and silty soils. Drummed and bulk wastes disposed at
this site include styrene, oily wastes, coal tar compounds, a
large quantity of foam materials, and other hazardous and non-
hazardous wastes. Total volume of waste disposed in the landfill
is believed to be 70,000 cu yds. In addition, it is estimated that
there is 30,000 cu yd of contaminated soil beneath the landfill.
The total leachate volume in the landfill is estimated at 7
million gallons. Ground water at this site is not presently
contaminated; however, there is potential for future soil, surface-
water, and ground water contamination from leachate.
Remedy Selected: Major components of the selected remedy include
the following: Dewatering landfill of leachate; leachate treatment
and discharge; RCRA Subtitle C cap; and deed restrictions, ground
water monitoring.
SUMMARY OF FINDINGS
I. Site Characteristics
The sizes of sites A, B, C, and D range from approximately 1 acre
to 17 acres. Sites A, B, and C are located on relatively flat
land, while a predominant feature of Site D is its rugged
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OSWER Directive 9835.13
topography with high relief. Even though sites A and D are closer
in size, the depth and rugged topography of Site D would make
excavation at this site much harder and would greatly increase the
short-term risks to workers.
Sites A, B, and C have extensive ground water contamination. At
Site B, other sources of ground water contamination exist.
Contaminants from the source area have not affected the ground
water at Site D.
II. Baseline Risk Assessment
EPA conducted the risk assessment for Sites A, B, and C. The risk
assessment for Site D was conducted by the responsible party. For
all sites, current risk from direct contact and ingestion of soils
were calculated using assumptions based on a trespassing scenario.
For Site A, risks were calculated only for soils outside the source
area; potential risks from soils in the source area were not
quantified. Current risks for soils outside the source area at
Site A were found to be less than 1 x 10"6 for ingestion. It was
presumed that risk would be higher in the source area. The maximum
current risk at Site B was from dermal absorption of contaminated
soils (1.5 x 10'2) , whereas the risk from ingestion was
8.8 x 10"5. Current risk for ingestion of soils at Site C was found
to be less than 1 x 10"6. Current and future risks from soil
ingestion at Site D exceeded 1 x 10"6 level for arsenic and
manganese only; however the ROD stated that these risks were
comparable to risks from naturally occurring background
concentrations of these substances in the U.S. Exposure to other
chemicals in soils at Site D did not exceed the 1 x 10"6 cancer
risk.
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OSWER Directive 9835.13
Three risk assessments were reviewed. There were inconsistencies
in the risk assessments reviewed. One risk assessment performed
by EPA was predicated on a worst case analysis, while another used
a low ingestion rate. At a site where the PRPs performed the risk
assessments (site D) low absorption factors were used and some
chemicals were not included in the group of indicator chemicals.
Potential future risks from source-area soils were calculated only
at Sites B and C. At Site A risks were not calculated for source-
area soils. At Site D, the present and future scenarios were the
same. Future risks from soils at Sites B and C were calculated
under the assumption that residents were living on site. Potential
maximum future risks from soils at Site B are 8 x 10"2 (dermal) and
1.4 x 10"3 (ingestion); for Site C ingestion risks range from 2 x
10"3 to 3 x 10"5.
Present and future risks from ground water exposure at all four
sites were calculated assuming daily use of ground water for
drinking and bathing. None of the drinking water wells near Sites
A and B were found to be contaminated. Maximum current risk for
ground water ingestion at the drinking water well at Site C is 1
x 10"4. Arsenic and two other chemicals exceeded the 1 x 10'6
carcinogenic risk level in ground water at Site D. Arsenic
contamination is believed to be from naturally occurring arsenic.
Concentrations of the other two chemicals were below MCLs. Current
risks from exposure to leachate at Site D exceeded 1 x 10"6 risk.
Potential future risks from ground water at Site A ranged from 1
x 10"2 (water table aquifer) to 4 x 10"5 (bedrock aquifer) .
Potential future risks from exposure to contaminated ground water
at Site B were found to be extremely high (greater than 1 for
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OSWER Directive 9835.13
ingestion)'. Potential future risk at Site C ranged from 1 x 10"1
to 1 x 10"3. Potential future risks at Site D were found to be due
to further contamination of ground water by leachate.
In summary, soils and ground water pose significant risks at Sites
B and C, and ground water at Site A also poses a significant risk.
Risks at Site D are due to potential of further contamination of
soil and ground water by leachate.
III. Remediation Goals/Remedy selected
Remediation goals at Sites A, B, C, and D included eliminating
direct contact risks from soils posing greater than 10"6
carcinogenic risk and reducing migration of contaminants from soils
to ground water. This will be accomplished by treatment of highly
contaminated material (principal threat) at Sites A, B, C, and D.
At Site A all wastes and contaminated soils would be removed and
incinerated. At Site B highly contaminated waste and soils will
be treated by low-temperature thermal treatment. At Site C the
principal source of contamination will be treated via soil vapor
extraction, and at Site D the landfill will be dewatered and
leachate collected will be treated and discharged. Since some
contaminated material is being left (under RCRA Subtitle C cap)
at Sites B, C, and D, deed restrictions on land and ground water
use will be placed at these Sites to protect the cap and prevent
the use of contaminated ground water.
The target cleanup goal for ground water at Site A is 10"6. Since
other sources added to the contamination at Site B, and since
cleanup to 10~6 would be below the detection limit for some
contaminants, 1 x 10"5 or attainment of MCLs, whichever is more
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OSWER Directive 9835.13
stringent was selected as the target cleanup goal for Site B. The
point of compliance will be monitoring wells at the down-gradient
edge of the slurry wall (from OU1) and RCRA Subtitle C Cap. site
C is an active industrial facility. The target cleanup level for
Site C is 10"6 and MCLs at waste boundary, nearest receptor. Ground
water monitoring is included as part of the remedial action for
Site D.
IV. Treatment vs. Containment
Selected remedial actions for all sites met NCP expectations in
that highly toxic and highly mobile wastes will be treated, and
engineering controls (capping) will be adopted for large-volume,
low-toxicity wastes.
All sites evaluated incineration of source materials. Total
incineration was selected only at Site A, the smallest site because
of implementation problems with capping. Capping at this site
would have required that approximately ten houses be demolished and
a road rerouted. Low-temperature thermal treatment of principal
threats (highly contaminated materials) was selected as the remedy
for Site B. Treatment of principal threats from VOCs at Site C was
handled via soil vapor extraction; incineration at this site would
cost approximately $53 million more than the selected treatment
alternative. At Site D, where the principal threat is from
leachate, the landfill will be dewatered and collected leachate
liquids will be treated and discharged to surface water. Since
some hazardous waste will remain at Sites B, C, and D, engineering
controls (RCRA Subtitle C cap) will also be implemented at these
sites.
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OSWER Directive 9835.13
V. involvement of PRPs and other influence
PRPs commented extensively on the RI/FSs and other technical
documents at the three Fund-lead sites. Substantial Regional
involvement and close oversight was required in the preparation of
the final FS for Site D (PRP lead). Public interest was also high
at the three Fund-lead sites. The PRP lead site generated very
little public interest.
The remedy at Site B was changed from incineration to low-
temperature thermal treatment to accommodate community concerns
regarding air emissions from incineration and to allow PRPs to
pilot test low-temperature thermal treatment. At a portion of Site
C not included in this comparison, based on additional technical
data provided by the PRPs, EPA changed the selected remedy from a
RCRA Subtitle C cap to a RCRA Subtitle D cap.
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OSWER Directive 9835.13
PAIRED ANALYSIS SUMMARY: FOB SITES
The independent selection panel chose five sites for the
paired analysis in the PCB category.
SITE DESCRIPTIONS
Site A RI/FS Lead - Fund RD/RA Lead - Fund
Site Description: This is a 1/2-acre site within a 9-acre parcel.
Activities at the site consist of a semi-active vehicle repair
facility and salvage yard. There was a spill of about 1000 gallons
of PCB dielectric fluid, which caused the site contamination. The
site surroundings are partially undeveloped, with some agriculture.
There has been surface migration of contaminants to between 6
inches and 2 feet of the soil. Near the spill area there is
localized ground-water contamination. The residences near the site
use private wells. The site is near a river. A former action
removed 800 cu yds of contaminated soil.
Remedy Selected: On-site solvent extraction with off-site
thermal destruction of hot spots where PCB concentrations exceed
50 ppm. Off-site incineration of concentrated extract.
Site B RI/FS Lead - Fund RD/RA Lead - Fund
Site Description: The site includes a 26-acre area. In the past
there was PCB disposal from industrial activities at the site. The
site setting includes active manufacturing, light industrial use,
commercial activities, and residences. Contamination extends very
deep, over 20 feet into the bedrock. The contaminated ground water
has not migrated off-site. There is some-surface water
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OSWER Directive 9835.13
contamination of a stream. In the past, 518 tons of soil
contaminated with PCBs greater than 50 ppm were removed.
Remedy Selected: On-site solvent extraction of unsaturated soils
with off-site thermal destruction of concentrated extract. On-
site thermal destruction is a contingent remedy if cleanup goals
cannot be achieved by solvent extraction.
Site c RZ/FS Lead - Fund RO/RA Lead - Fund
Site Description: This site has been contaminated by waste oil
containing PCBs used to fire boilers at a greenhouse. There are
«
contaminated lagoons on site. Soil contamination extends to 40
feet; contamination decreases with depth. The shallow ground water
is contaminated, but the deep aquifer is not because of a clay
layer of very low permeability. A past ROD provided for
remediation of highly contaminated source materials in oil, pits,
lagoons, and surrounding soil by on-site incineration.
Remedy Selected: On-site thermal destruction of hot spots
containing dioxin and construction of a synthetic cap over the
majority of soils that are close to health-based levels.
Site D RI/FS Lead - PRP RD/RA Lead - PRP
Site Description: This 9-acre site is located within a larger
65-acre expanse of property with residences adjacent to the site.
The site consists of former transformer work areas, a scrap area,
and two lagoons. There are numerous contaminants in addition to
PCBs, including polyaromatic hydrocarbons (PAHs), chlorinated
benzene, and lead. Soils are contaminated to a depth of 10-12 feet
near transformer work areas, and there is ground-water
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OSWER Directive 9835.13
contamination. Past removal actions involved removal of tanks and
containers and installation of fences and signs.
Remedy Selected: On-site solvent extraction with off-site
thermal destruction of concentrated extract and post-extraction
treatment of some materials before disposal.
Site E RI/FS Lead - PRP RD/RA Lead - PRP
Site Description: This 4.8-acre active manufacturing site with
an unlined wastewater lagoon and sludge pit is in a mixed
industrial and residential area within a flood plain. No previous
removal actions have taken place. There are more than 5,500 cu yds
of sludge in a basin and pit on the site. Sludge (3,300 cu yds)
has also overflowed to a wooded swamp. The PCBs are in the upper
part of the sludge in the swamp area. The sludge consists
primarily of aluminum oxyhydroxides, calcium carbonate, and calcium
sulfate, and metals. The extent of ground-water contamination will
be addressed as a subsequent operable unit.
Remedy Selected: Excavation and off-site reclamation, if
available, or treatment to meet RCRA LDRs using the best
demonstrated available technologies. Off-site thermal destruction
of hot spots where PCB concentrations exceed 500 ppm.
SUMMARY OF FINDINGS
I. Site Characteristics
The source areas at the sites were somewhat different because of
differences in the operations that contaminated the sites. At
Sites A and D, PCB contamination resulted from handling capacitors
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OSWER Directive 9835.13
and transformers; at Site B, from industrial waste disposal; at
Site C, from waste oil tanks and pits. In contrast, PCBs were
found in some sludge materials at Site E.
Contamination at Site A is predominately restricted to the 1979
spill area and at Site E to the two disposal areas where disposal
occurred relatively recently. Disposal practices at Sites B, C,
and D occurred over several years, involved several on-site
disposal areas, and have resulted in extensive surficial and
vertical migration of contamination. At Site D, the contamination
extends 10-12 feet. At Site B the extent of contamination is
greater than 20 feet, and the deep aquifer is contaminated. At
site C surface contamination covers an extensive area; however, the
confining layer prevents vertical migration of contamination to the
deep aquifer.
The close proximity to residential areas and current use of the
sites vary. Residences are close to Sites A, B, and D, and two
persons (PRPs) reside on Site C but will relocate before
remediation begins. At Sites A and B industrial use continues.
Industrial use also continues at Site E, although not in the
contamination area.
II. Baseline Risks
EPA performed the risk assessment at all sites except Site E. For
Site E, the PRPs conducted the risk assessment, with EPA oversight.
The primary exposure routes at all sites were direct contact and
ingestion of ground water (except for Site E, where ground water
will be addressed as a subsequent operable unit). In addition,
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OSWER Directive 9835.13
there were environmental risks at Sites B and D. Other than PCBs,
the chemicals to which people could be exposed varied among the
sites.
Two risk assessments were reviewed and no variances were found.
The present risk at the sites was based on varying exposure
scenarios. At all sites the risk was premised on direct contact
by nearby residents who could enter the site. In addition, since
industrial use continues at Sites A, B and E, direct contact
exposures of workers to surface contamination were evaluated. For
Site B, the risk assessment, separates residential and worker
exposures for the site, because access to some areas of
contamination would be limited to workers.
The future risk at all sites was based upon an on-site residential
scenario. For all sites (except Site E) , future residential risks
from ingestion of on-site contaminated ground water and direct
contact with contaminated surface soil was evaluated because
residential areas are adjacent to the sites; at Site B residents
are living on-site but are not consuming ground water. Again,
direct contact with PCB-contaminated soils represents the highest
potential future risk.
The baseline risk was greater than 10'3 at all sites and was
primarily due to PCBs from current direct contact risks to
residents and workers, and to future ingestion of PCBs and organics
in on-site ground water.
III. Remediation Goals
The remedial goals at Sites A, D, and E provide for unlimited
future residential use. Of the five sites, these three had a
lesser extent of contamination. Also, for Site B, industrial use
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OSWER Directive 9835.13
areas of the site will receive partial treatment and containment,
and soils near residential areas will be excavated and treated to
achieve 1 by 10"6 levels and MCLS. For Site C, a previous ROD
addressed highly contaminated materials, and the 1989 ROD specified
that containment of the remaining contamination would approach
health-based levels.
Principal threats will undergo treatment at all sites. Sites A,
B, and D involve excavation and treatment. At Site C, treatment
of some areas containing dioxin is provided in this ROD, and
treatment of major source areas is provided in a prior ROD. In
addition, at Sites A, B, and D there were prior removals of highly
contaminated materials.
At all sites, the remediation goals to protect against direct
contact threats and ingestion of ground-water were in the 10"5 to
10"6 range, with a hazard index less than 1.0 for non- carcinogens.
The variation within the 10"5 to 10'6 range appeared to be based in
part on the EPA Region where the Site was located. Sites A, B, and
D were in one Region where the goal was at least 10"5 whereas Sites
D and E were in a different Region where the goal generally was
lO'6.
In addition, there were other variables. One variable was
commercial areas. At Site B, the areas near residents and
wetlands will be remediated to 10"6, while commercial areas, will
be remediated to 10"5 with soil cover which, as indicated by the
TSCA program, would reduce the risk by about one order of
magnitude. Site B did start with a 10~6 point of departure for the
remedial action goal for the commercial area, but it was adjusted
to 10"5 after weighing the technical feasibility of removing soils
under a building down to bedrock. Moreover, state ARARs and
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OSWER Directive 9835.13
environmental concerns resulted in more protective cleanup goals
at Sites A and D. In addition, the presence of another
contaminant, dioxin, affected cleanup goals at Site C. Finally,
RCRA clean closure levels will affect Site E levels.
A complete comparison of remediation goals in terms of
concentrations of contaminants is not possible because these were
identified by one Region (Sites A, B, and D) and not another (Sites
C and E).
IV. Treatment vs. Containment
All of the selected remedies are consistent with NCP and Superfund
program expectations. All RODs considered incineration, innovative
treatment of principal threats, as well as containment remedies.
Different treatment remedies were chosen for the sites based on the
consideration of specific criteria as presented in the NCP. The
criteria that were most important for the sites depended on site-
specific factors. A total incineration alternative was not
selected for any site due to high costs and other site-specific
factors.
As indicated above, at Sites A, D, and E all source materials above
health-based levels will be excavated to allow for unrestricted
future residential use (direct contact and ground water). sites
A and D will employ on-site solvent extraction with off-site
thermal destruction of concentrated extract. At Site D, this is
supplemented by post-extraction treatment as necessary before off-
site disposal, at Site A, by off-site incineration of soils with
relatively high levels of contamination. Site E involves off-site
incineration of a relatively small amount of highly contaminated
material. The sludge material is within RCRA waste F019. The
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OSWER Directive 9835.13
remedy complies with the proposed land disposal restriction
providing for chemical oxidation-reduction and/or stabilization.
The two sites where contaminants will remain at concentrations
above health based levels have the most contamination. The Site B
remedy involves solvent extraction with off-site incineration of
the residuals. A past ROD for Site C selected incineration of
highly .contaminated areas, and the more recent ROD specifies
containment of other areas.
For Site E, the selected remedy of excavation followed by off-site
treatment included contingencies in order to comply with RCRA LDRs
which were only proposed at the time the ROD was signed. The on-
site C cap is a result of a second ROD that responded to lower
levels of contamination. The remedy was considered to be effective
in part because of the nearly impermeable cap and because of a
confining layer above the lower aquifer.
V. Involvement of PRPs and Other Influences
PRP involvement did not influence EPA to select less effective or
less protective remedies at the PCB sites. For Sites D and E,
Enforcement-lead sites, the selected remediation goals will allow
for unlimited future access, and cleanup goals for these sites are
considered protective of human health and the environment. At the
Fund-lead Site C, PRPs were active in reviewing and commenting on
the remedial approach.
Community concerns affected the remedy selection decisions for some
sites, in particular, complete incineration of all contamination
was not selected in part because of public opposition at Site C.
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OSWER Directive 9835.13
For Site D, citizens expressed a desire to have no restricted
future uses of the site.
State involvement affected the remedy selection at a few sites,
particularly at Site A, where the State modified the remediation
goal and requested that the treatment residuals receive post
treatment and be disposed off-site rather than on-site.
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OSWER Directive 9835.13
PAIRED ANALYSIS SUMMARY: SOLVENTS SITES
The independent selection panel chose four sites for the paired
analysis in the solvents category.
SITE DESCRIPTIONS
Site A RI/FS Lead - Fund RD/RA Lead - Fund
Site Description: The site is roughly 50 acres in area, of which
about 25 acres were contaminated by a former, on-site waste oil and
solvents recycling operation. The site is in a rural setting with
croplands and uncultivated areas, along with residential and
industrial development. Residences and a high-density residential
facility adjoin the site. In addition to oil residues, the main
contaminants are VOCs, PAHs, PCBs, phenols, phthalates, pesticides,
and metals. There are nine separate contaminated areas, lying
mainly in a flood plain. Buried wastes consisting of sludges and
filtering materials from site operations are in one site area,
whereas contaminated soils and sediments, ranging to depths of 15
feet are found in the remaining areas. Contaminated ground water
occurs in alluvial overburden and bedrock at the site. The river
adjacent to the site receives surface drainage and ground-water
seepage.
Remedy Selected: Excavation and on-site thermal treatment for
waste materials from one area and the contaminated on-site
sediments, with backfilling or solidification and backfilling of
the residues (depending on toxicity) ; contaminated source materials
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OSWER Directive 9835..13
left in place in other areas and covered either with a stabilizer
layer and revegetated soil or with revegetated soil only; deed
restriction to prevent on-site soil disturbance and well drilling.
site B RI/FS Lead - Fund (State) RD/RA Lead - Fund
Site Description: The site comprises 20 acres, where nearly 10
acres are contaminated by off-site industrial waste disposal from
a former salvage operation for containers used to store and
transport chemicals/chemical wastes. The site, with an on-site
residence, is located in a wooded area among small farms and
residences in a rural-agricultural setting. site soils and the
upper portion of the shallow aquifer are contaminated by VOCs,
semi-volatiles, and PCBs. The ground water also contains metals.
A removal action conducted earlier eliminated the major
contamination in source materials.
Remedy selected: Flushing system for soils to remove low-level
residual contamination from further contaminating groundwater in
a portion of the site; vegetative soil cover over the complete area
of contamination; if found, contaminated soils in hot-spot areas
will be excavated and incinerated; ground water pumping and
treatment; access restriction by fencing during remedial actions;
deed restriction for notification of on-site intrusive activities.
Site C RZ/FS Lead - RP RD/RA Lead - Fund
Site Description: This site is a 7-acre, abandoned, industrial
waste storage and disposal facility in a semi-urbanized area.
There is light industrial and commercial development nearby, with
the nearest residence about a mile away. Remnants of natural areas
and wetlands surround the site. The principal contaminants are
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OSWER Directive 9835.13
VOCs, including benzene, toluene, and TCE; other organics,
including PAHs, PCBs, and phenols; and metals. VOCs are less than
0.4% in source materials. Roughly 3.5 acres of the sandy soils and
fill are contaminated to depths that extend beneath the 10-foot-
deep water table at the site. Sediments adjacent to the site also
are contaminated. A plume of contaminated ground water leaves the
site, although the surficial aquifer is also contaminated from
multiple other sources and is saline. Private wells, not intended
as a source of drinking water, are about a mile away from the site.
Contaminated ground water and surface waters from the site seep
into the wetlands and an adjacent drainage way. An earlier surface
removal action took place at the site.
Remedy Selected: On-site treatment of soils and sediments by soil
vapor extraction followed by solidification/stabilization followed
by on-site deposition; final RCRA cover, if applicable (determined
by testing of solidified materials) ; ground-water pumping and, deep
well injection or treatment (for hazardous substances) and either
deep well injection or aquifer reinjection (for treated, salt-
contaminated water); restrictions on site access and deed
restrictions, as necessary.
Site D RI/FS Lead - RP RD/RA Lead - Fund
Site Description: The site comprises roughly 4 acres and is an
abandoned, off-site industrial waste storage, recycling, and
disposal facility. The site is within one-quarter mile of a
residential development and is located in a semi-urbanized area of
mixed residential, commercial, and light industrial land use. It
is bordered by commercially developed land and undeveloped land
having low sand dunes and wetlands. About 2.6 acres of sandy soils
and fill at the site have contaminated soils that extend below the
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5-foot-deep water table. The major contaminants at the site are
VOCs, including benzene, toluene, and TCE; other organics,
including PAHs, PCBs, and phenols; and metals, including chromium,
and lead; and cyanide. VOCs are as high as 1.1% by weight in
source materials. Contaminated ground water has migrated off-
site; however, the aquifer is saline and contaminated from multiple
other sources. Contaminated ground water seeps into adjacent
wetlands; surface water runoff from the site also enters the
wetlands. A prior removal action for surface materials took place
at the site.
Remedy Selected: On-site treatment of soils by a combination of
vapor extraction and solidification/stabilization with on-site
deposition of solidified materials; final RCRA site cover if
applicable (depending on testing of solidified materials); ground-
water pumping and deep well injection or, treatment of hazardous
constituents and either deep well injection or aquifer reinjection
of the salt-contaminated effluent; restrictions on site access and
deed restrictions, as needed.
SUMMARY OF FINDINGS
I. Site characteristics
Although site-characteristics have similarities, there are also
differences in features which make each site distinct.
Physical conditions at the sites have both similarities and
differences. Site A is mainly situated in a flood plain adjacent
to a major river where it is underlain by alluvial soils and other
overburden. In contrast, Site B is in an upland area having
permeable sandy soils, and Sites C and D are each in partially
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filled lowland areas with wetlands in sand dune and swale
topography occurring adjacent to the sites.
Sizes of the sites differed, as did the operational and waste
management practices that took place at some of the sites, which
have bearing on the distribution of contaminated materials. Site
A is larger than the other sites; it is a former recycling facility
for waste oils and solvents. Wastes (sludges and filter materials)
from processing were disposed of in nine separate areas covering
a total of 25 acres. At Site B, drums and pails were recycled,
which resulted in discharges of residuals from the containers as
well as solvents that were used in the cleaning process. As
compared to Sites A, C, and D, relatively lower volumes of wastes
and solvents were released in the 10-acre contaminated area at Site
B. Sites C and D (operated under the same general ownership and
waste management practices), are abandoned facilities which
accepted large volumes of bulk and liquid industrial wastes for
storage, recycling, and disposal. Roughly 2.5 acres of land at
Site C and 3.5 acres at Site D have source materials remaining on-
site that are generally contaminated above levels of concern.
Greater volumes of waste were disposed of at Site D than Site C.
Types of contaminants at the sites, although similar (predominantly
solvents), differ in concentrations. Contamination may be
categorized as organics/metals at Sites A, C, and D, as opposed to
organics at Site B. Site A has one area where concentrated
processing wastes are found; contaminant levels in source materials
are higher at this location than in the other areas of soils and/or
sediment contamination. Site B, as now known, has only relatively
low-level contamination in source materials subsequent to the
earlier removal action. Sites C and D have generally higher levels
of contamination that remain after removals at the sites, than at
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any of the other sites. Site source materials exhibit higher
contamination at Site C than at Site D. Ground water at all four
sites is contaminated.
Variations in site setting are found among the sites. Site A is
in a rural area with mixed agricultural, residential, and
industrial land use. Site B is in a rural, agricultural area with
scattered residential development and includes an on-site
residence. Sites C and D are each in semi-urbanized areas with
mixed residential, commercial, and light-industrial development.
The area surrounding Site C is more developed than that near Site
D. Although further residential development is unlikely near
either Site C or Site D, there is a greater chance that such
development will occur near Site D.
II. Baseline Risks
Similar exposure routes were examined in the risk assessment for
the four sites. In all cases, the greatest threats were determined
to be associated with ingestion of contaminated soils and ingestion
of contaminated ground water. Other exposure routes associated with
or incidental to ingestion were sometimes included in the exposure
scenarios representing the greatest threats. With regard to Site
A, incidental exposures were considered along with ingestion for
both source materials and ground water; modelling was used to
estimate the affects of contaminated ground water on the water
quality of the river, a downstream source of drinking water, and to
estimate risks from ingestion of fish from the river. For Site B,
exposure routes were screened to eliminate incidental exposures,
with only the routes presenting the greatest exposure and potential
health threats (i.e., ingestion of contaminated soil and of
contaminated ground water) used in risk estimation. Ingestion of
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contaminated soils and ground water connected with Sites C and D
included incidental exposures, for which inhalation of volatiles
during household use of ground water made a significant increase in
estimated risks.
Three risk assessments were reviewed and the two Fund-lead risk
assessments selected ultra-conservative exposure assumptions.
Specific indicator chemicals, selected from the contaminants
presenting the greatest threats at the sites, were used as the basis
for risk calculations at Sites A and B. For Sites C and D, however,
risks were estimated from exposure to all hazardous substances found
at the sites.
There were different determinations of current and future threats.
In the baseline risk assessment for Site A, current exposures to
source materials were examined, but only future exposure to ground
water was considered since the only on-site well was closed due to
contamination which the ROD indicates was not associated with the
site. At Site B, the risk assessment was predicated upon both
current and future options for land and ground water use. For Sites
C and D, the risk assessments were based on future development of
the sites and site areas, without site remediation, including
exposure to soils, sediments, and surface waters, and residential
use of the ground water. Information was not given for exposures
under present conditions. (There is now security fencing around
both Sites C and D.)
Estimated maximums for cumulative, lifetime carcinogenic risks (in
rounded numbers) ranged from 4 x 10"4 to 3 x 10"6 for soils/source
materials and 2 x 10 to 5 x 10 for associated ground water at the
sites. By site, for soils these are 6 x 10"5 for Site A,
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3 x 10~6 for Site B, 4 x 10"4 for Site C, and 7 x 10~5 for Site D.
For ground water they are 2 x 10"1 for Site A, 5 x 10"3 for Site B,
3 x 10"2 for Site C, and finally, 5 x 10~2 for Site D.
Corresponding estimates of non-carcinogenic risks (as indices) were
calculated but are not shown here. All sites were considered to
have non-carcinogenic risks from contaminants in source materials
and ground water.
III. Remediation goals
Remedial goals for the sites are based on current and anticipated
future use of the sites and the site areas. The remedial objectives
for Site A are somewhat different from the objectives for Sites B,
C, and D. Objectives for Site A are to reduce risks associated with
exposure to contaminated materials in the site areas and to prevent
exposure to contaminated ground water beneath the site, located in
a flood plain area. For Sites B, C, and D, there may be future
development since they are upland locations. The ROD for site B
contemplated unrestricted use of the site arid area, including
residential use, while the RODs for Sites A, C, and D did not
specify the nature of possible development. Remedial goals for
source materials are not established for Site A; however, maximum
limits for no action were determined at approximately 10"5 for one
area, 10"5 to 10"6 for four areas, and 10*6 for the other four
contaminated areas. At Site B, an objective for remediation of
source materials is to prevent further contamination of ground
water. Additionally, since the site is to be returned to conditions
for unrestricted or residential use, a cleanup goal of 10"6 is
established. Remedial objectives for Sites C and D are to reduce
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health threats to future development of each of the sites. Remedial
goals for soi
respectively.
goals for source materials at Sites C and D are 10'5 and 10~6,
Ground water goals also differ among the four sites. According to
the ROD, conditions for establishing Alternative Concentration
Limits (ACLs) for ground water are met at Site A, CERCLA ACLs are
established in the ROD because of the flood plain location. Well-
drilling restrictions, furthermore, are determined to be a necessary
part of any remedial action. Remedial goals at Site B are 10"6 or
the attainment of MCLs for allowing unrestricted use, corresponding
to site land use. For Sites C and D, the remedial goals for ground
water (10'5 amd the attainment of MCLs) are less stringent than at
Site B due to: the semi-industrialized settings, the multiple other
sources of contamination, and the unacceptable salt in the ground
water from off-site areas and fill.
Differing approaches for determining the risk-based need for
remediation and remedial goals occurred among the sites. The Region
where Site A is located uses internal peer review and evaluation by
toxicologists and appropriate experts to determine these. Under
this method, the remedial goals may, or may not have definite
relationships to EPA's accepted risk range. Another Region, with
Sites B, C, and D uses 10"6 as the cleanup goal and as a lower
boundary point of departure for determining relative need for
cleanup, unless conditions at the site and within the area of
influence of the site suggest differently.
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IV. Remedies Selected
The selected remedy for Site A combines treatment of contaminated
materials (i.e., waste filtering materials and sludges) by
excavation and incineration from the site area that poses the
greatest threats, combined with soil covering or no action for the
other contaminated areas. On-site thermal treatment (incineration)
and backfilling of treatment residues (ash) was selected because it
provides a permanent and cost-effective remedy for the wastes,
although capping requirements for the residues remains to be
determined. In certain areas of site A, the addition of a layer of
stabilizer followed by placement of a revegetaged soil cover or
placement of a revegetated soil cover only are selected as remedies
for the less-significant contamination. No Action is considered
appropriate for two areas having minimal risks. After remediation,
Site A still requires restricted access and restrictions on well
drilling and use of ground water.
In order to reduce leaching of contaminants into the ground water
at Site B, soil flushing is selected to further reduce levels of
contamination in a portion of the contaminated area where the levels
in the soil remain the highest after the past removal actions. The
levels are relatively low, thus further treatment is not warranted.
According to the ROD, it is expected that the flushing will provide
the reduction in soils contamination to prevent further ground-
water degradation since organic chemicals in source materials are
the concern; metals in soils are not considered to be a problem.
As an additional measure prior to soil flushing, the ROD provides
for investigation and excavation and incineration of material
containing a particular organic contaminant which may be present at
higher levels in hot spots. Soil covering and revegetation of the
entire area of contamination is to take place because contaminated
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materials are being left in place, at least to some extent.
However, upon completion of soil and ground-water remediation, Site
B will have unrestricted land and ground-water use.
For Sites C and D, there is a contingency in the selected remedy
which affects only the ground-water portion of the remedy. For
source-control at each site, solidification/stabilization is
selected as the principal component for materials above the water
table. The ROOs indicate that this is the least expensive
alternative that will permanently reduce the toxicity, mobility,
and volume of the source and be fully protective; implementation,
however, depends on results of treatability tests.
Solidification/stabilization will be considered successful when it
reduces the mobility of contaminants so that leachate from the
solidified mass will not cause exceedance of health-based levels in
the ground water. Pretreatment by soil vapor extraction is included
in the remedy for Site D but not for Site C. It is intended to
reduce VOCs (greater than 1% by weight), which are still in soils
after the removal action, until they are below levels that would
pose a health threat and to levels that will allow
solidification/stabilization to proceed successfully. Depending on
toxicity levels, a RCRA cap or soil covering will be placed over the
stabilized mass at each site to reduce residual risks. Emissions
at Sites C and D from soil excavation and handling,
solidification/stabilization, and ground-water treatment, as well
as soil vapor extraction at Site D are to be controlled. Both Sites
C and D are expected to have land capable of being developed to some
extent, although residual risks from contamination will be different
for the sites. Ground-water cleanup for the sites will permit
future use, although at degraded quality.
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The ROD for Site A established CERCLA ACLs for ground water. Ground-
water remediation for Site B is by treating water that is extracted
by pumping operations, until the MCLs are met. For Sites C and D,
ground-water contingencies are to: pump and deep well inject the
contaminated water; if the salinity is not being removed, pump,
treat, and either deep well inject or aquifer reinject the effluent
from treatment (if aquifer reinjection does not cause spreading of
the existing salt plume). For the portions of the aquifer affected
by each site, 10"5 levels and MCLs are to be reached in remediation.
Maximum allowable contaminant concentrations were not established
for source materials and ground water at Sites A and B but were
established for Sites C and D; CERCLA ACLs were set for ground water
at Site A. These allowable levels were determined by calculations
based on remediation goals using carcinogenic and non-carcinogenic
risks.
Selected remedies for the sites are all consistent with the goals
of the NCP. That is, the remedies reduce the mobility, toxicity,
and volume of the contaminated materials, with treatment preferred,
or treat the principal threats or hot spots and contain the lower
levels of contaminated materials.
Levels of contamination and economics play a role in remedy
selection. For Site A, on-site incineration was chosen for
contaminated materials posing the highest threats, which mostly
consist of highly concentrated wastes, and areas of lower-level
contamination were remediated by soil covers. At Site B, due to
relatively low contamination levels and sandy soil, incineration
was not considered except for possible hot spots, which may or may
not be identified. Soil flushing using treated ground water
alleviates disposal problems for effluent from ground-water pumping
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and treatment, assuming the contaminated ground water and flushed
contaminants are collected and treated effectively. Since soil
vapor extraction and solidification/stabilization at Site D, and
solidification/stabilization at Site C are considered to be as
effective in reducing mobility and toxicity as the other full-
spectrum treatments evaluated, there were considerable cost savings.
V. Involvement of PRPs and Other Influences
The PRPs of Site A for which the Fund conducted the RI/FS agreed
with the selected remedies for all but one of the contaminated
areas, the area with materials slated for incineration. PRPs for
Site B did not offer substantive comment regarding remediation.
For each of Sites C and D, the PRPs initially did not respond to
court actions to conduct the RI/FSs but later took over the work
and agreed to continue the work following EPA's work plans. The
RI/FSs prepared by the PRPs indicted that solidification/
stabilization would be effective. After modifying the RI/FSs, EPA
proposed that remedy for the sites, but added soil vapor extraction
for Site D to treat the volatiles. The PRPs commented extensively
on the proposed remedies. Because of the comments, the option for
reinjection of treated ground water into the saline aquifer was
added as an alternate to deep well injection, if spreading of the
salt plume is not caused. PRP comments, therefore, did not
substantially alter the selected remedies for Sites C and D,
although a possible alternative was added.
The state concurred with the selected remedy for Site A, although
conditions for the concurrence were stipulated. For Site B, the
state conducted site investigations under cooperative agreement with
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EPA. The state's position was reflected in the reports used by EPA
in preparing the ROD, upon which the state concurred. Remedies for
Sites C and D had state backing and concurrence.
Public comment on remedy selection at Site A was not substantial,
although there was opportunity for input through public meetings.
Community interest in Site B was nominal, without preference for a
particular remedy. Public interest in Sites C and D was moderate.
The main comments were questions relating to deep well injection,
as well as opposition to it. Changes in the selected remedies were
not necessary because of public participation in remedy selection.
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PAIRED ANALYSIS SUMMARY: WOOD PRESERVING SITES
The independent selection panel, chose four sites for the paired
analysis in the wood preserving category.
SITE DESCRIPTIONS
Site A RI/FS Lead - Fund RD/RA Lead - Fund
Site Description: This 55-acre abandoned facility consists of waste
piles (5000 cu yd) and sediments (150,000 cu yd) contaminated with
polynuclear aromatic hydrocarbons (PAHs) which have been targeted
for remediation. The site is adjacent to a residential area.
Remedy Selected: On-site thermal destruction.
Site B RI/FS Lead - Fund (State) RD/RA Lead - Fund
Site Description: This 100-acre site is an abandoned facility that
was redeveloped for residential and commercial use. Contaminated
soil from the residential area (20,000 cu yd) and industrial area
(9,500 cu yd) and contaminated material from waste lagoons (40,000
cu yd) have been targeted for remediation. Contaminants of concern
are PAHs, pentachlorophenol (PCP), and some dioxins/furans.
Remedy Selected: On-site supercritical fluid extraction followed
by off-site thermal destruction of concentrated residuals.
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Site C
RI/FS Lead - PRP
RD/RA Lead - PRP
Site Description: This active industrial facility was formerly a
wood-treating facility and has soil contamination in waste pit and
dip areas consisting predominantly of PAHs, PCP, and some
dioxins/furans. The RI/FS identified 15,000 yd3 of contaminated
material for remedial action. Residential area is nearby. Ground-
water contamination is a major focus of this ROD.
Remedy Selected:
unit.
On-site bioremediation in a lined land treatment
Site D RI/FS Lead - PRP (State oversight) RD/RA Lead - PRP
Site Description: This 105-acre active wood-treating facility has
soils and sediments from former lagoons and drip areas contaminated
with PAHs, PCP, and some dioxins/furans. The remedial
investigation/ feasibility study (RI/FS) identified 15,000 yd3 of
contaminated material for remedial action. The closest residence
is 3/4 of a mile away; few residents are near the site. Ground-
water remediation is the primary focus of remedial action at this
site.
Remedy Selected: On-site bioremediation in an "engineered cell."
The RODs for all of these sites are final source-control actions.
Sites A, C, and D also include ground-water actions as part of the
current Records, of Decision. No-Action was selected for ground
water at Site B in a previous ROD. Interim actions previously
occurred at Sites B and C to limit exposures or prevent contaminant
migration.
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SUMMARY OF FINDINGS
The following conclusions can be drawn from the analysis for these
four wood preserving sites:
I. Site characteristics
The contaminants present in soils at the four sites are similar and
resulted from oil-borne wood preserving processes. PAH
contamination is present at all sites. Sites B, C, and D also have
contaminated pentachlorophenol (PCP) and dioxins/furans.
The volume of contaminated soils, which varied from 15,000 cu yd to
155,000 cu yd, was a factor affecting the implementability of
particular remedies.
II. Baseline Risk Assessment
Major exposure routes considered for the four sites varied.
Exposure pathways of concern at Site A included ingestion of
contaminated ground water, ingestion of contaminated soil, ingestion
of contaminated sediments, and dermal contact with bayou sediments.
For the 1989 ROD at Site B, only risks due to exposures to
contaminated soil were investigated. A 1986 ROD selected natural
attenuation for the contaminated ground water, which is not a
potential source of drinking water. For Site C, ingestion of soil,
inhalation of contaminants attached to soil, dermal contact, and
ingestion of ground water were considered in the baseline risk
assessment. For Site D, risks associated with consumption of
contaminated ground water and inhalation of volatilized contaminants
from the site were the only exposure routes quantified. No direct
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contact or on-site exposures were considered in the risk assessment
for Site D, despite the presence of surface contamination. (Note:
Site D was State-lead and EPA did not concur on the risk
assessment.)
Only one risk assessment was reviewed. This risk assessment
performed by the PRPs used some limited exposure assumptions and
eliminated some chemicals which may underestimate risk.
Risk assessments for Sites A, B, and C considered both residential
and commercial use of the land. Site A is currently adjacent to
residential areas but is not expected to have residents living on
site. Commercial use or recreational use is more likely. For Site
B, these land uses represent both the current and future use
expected for the site, since it is currently used for both purposes.
For Site C, the current land use is industrial but the risk
assessment addressed future residential use of the land, current
industrial use, and future on-site construction. At Site D the risk
assessment focused on future residential use adjacent to the site.
No risks for the industrial land use were considered, despite that
being the current and future land use.
Risks at site A were initially considered before Superfund risk
assessment guidance was issued in 1986; therefore different
methodology was used to consider risk. For this site, instead of
calculating a baseline risk, an action level that was associated
with acceptable risk (10~5 excess cancer risk for residential use,
10~6 excess cancer risk for commercial use) defined areas of the
site that would require cleanup. For Site B, worst-case lifetime
excess cancer risks associated with residential exposure are
estimated to be no greater than 7 x 10"2. The lifetime excess cancer
risk associated with future residential use of Site C is 4 x 10"3 for
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the site as whole. For industrial use and construction worker
scenarios at Site C, the lifetime excess cancer risk associated with
the site as a whole is approximately 2 x 10"4. Residential use of
the ground water (2 liters of water per day) is associated with a
risk of 3 x 10"4 excess cancer risk. For Site D, the estimated total
excess incremental cancer risk due to consumption of drinking water
is between 2 x 10"4 and 5 x 10"4. An inhalation risk was calculated
assuming that a residence was established immediately adjacent to
the site, and the lifetime excess cancer risk was estimated to be
1.5 x 10"5. No on-site or direct contact exposure was considered at
Site D; these exposures may potentially be associated with risk.
Consideration of on-site exposures to workers at a currently
operating facility is inconsistent between the two active industrial
sites. Exposures to on-site workers was evaluated at Site C
according to Superfund risk assessment guidance. Direct contact was
not considered at Site D because the PRPs argued that because the
facility was currently operating, any workers that may have access
to the surface contamination at the site would be observing OSHA
regulations and would therefore not be exposed to harmful
contamination, which discounts inadvertent exposure to
contamination. (Note: Site D was State-lead and EPA did not concur
on the risk assessment.)
Site D also assumed that fencing would be sufficient to eliminate
direct contact exposures. The PRPs argued that because the facility
is active and surface contamination was present in secured (fenced)
areas of the site, no trespassers would have access to the site.
Sites A, B, and C quantified the risk of direct contact to
contaminants at the site.
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The threat' of dioxins/furans was not handled consistently between
the sites. At Sites B and C, a dioxin-equivalence approach was used
to evaluate the risk of dioxins and furans. However, with
apparently comparable levels of contamination, dioxins and furans
were eliminated from consideration at Site C but at Site B were
considered a significant concern. At Site D, concentrations were
compared to an ATSDR action level and determined to be below a level
of concern. (Site A had no dioxins or furans or their precursors
on the site.) A consistent policy on addressing dioxin/furan
contamination would be useful.
III. Remediation Goals
Two Sites, A and B, developed cleanup goals assuming frequent
exposure due to residential land use either on or adjacent to the
site. At Site A, it was anticipated that residents would remain
adjacent to the site but that no residences would be on-site. At
Site B, cleanup goals were developed assuming current residents will
remain on-site. Cleanup goals for Sites C and 0 assumed that the
sites would remain industrial. At Site C, cleanup levels will allow
unrestricted industrial use of the site. For Site D, institutional
controls (OSHA requirements) are factored into the cleanup decision.
Site conditions resulted in different remedial action objectives at
the different sites. Although some ground water was remediated at
Site A, direct contact was the primary concern to be addressed.
Site B was remediated primarily to prevent direct contact exposures.
At Site C, remedial action focused on both ground water remediation
and prevention of direct contact exposures. At Site D, soil and
waste pits were remediated primarily to prevent further
contamination of ground water. Direct contact could have been
considered here but was not.
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IV. Remedy Selected
Some form of treatment was used at all four sites. Incineration
was selected for Site A. Critical fluid extraction and incineration
of the concentrate was selected at Site B. Biotreatment was
selected for the two Enforcement-lead sites.
Two different biotreatment technologies were examined. For Sites
C and D, a landfarming type of biotreatment is contemplated, which
is less costly than incineration if space is available. Sites A
and B do not have space available for landf arming, so a biotreatment
reactor was examined. Bioreactors cost as much or more than
incineration at Sites A and B.
Three of the sites (A, B, and C) used consistent, risk-based
approaches in determining remediation goals that were expressed as
contaminant concentrations in soil. Consistent levels were selected
for remediation, given the exposure assumptions appropriate for
these sites. These three sites all had residents living on or near
the site. A 10"5 lifetime excess cancer risk level was chosen for
the residential use of Site A, because residential use of the site
is unlikely, but residential areas are adjacent. An excess cancer
risk of 10"6 was chosen as the goal for the residential portions of
Site B because residents are living on site and will continue to do
so. The commercial portions of Site B will be cleaned up to 10"5
excess cancer risk level, as will Site C, a currently operating
industrial facility.
At the fourth site (D) , which is an active RCRA facility with no
nearby residents, the cleanup goals were selected based on source
removal to preclude further ground water contamination, as opposed
to direct-contact risks. The ROD for Site D calls for bioassays on
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the soil to determine that the soil presents no greater than a
10"6 excess cancer risk. However, there is no established protocol
for using soil bioassays to relate to cancer risks.
V. Treatment versus containment
A treatment remedy, consistent with the expectations in the proposed
NCP, was chosen for all four of these sites. At two Enforcement
sites biotreatment was selected; at the other two Fund-lead sites,
incineration was selected.
Long-and short-term effectiveness, implementability, reduction of
toxicity, mobility, or volume through treatment, and cost were
important criteria in deciding what method of treatment was
appropriate. Both incineration and biotreatment will achieve
significant reduction in toxicity, mobility, or volume of
contamination at the sites.
Time of implementation was a significant factor in the Fund
selecting incineration over biotreatment at Sites A and B. This
decision was influenced by the existence of residents on or adjacent
to both sites and the respective Region's concerns to limit the
residents' short-term exposure. Capping is included as part of the
remedy at all Sites. At Sites A and B, low-level waste (i.e., below
a health-based action level) will be contained in place. At Site
C, all source contamination above the concentration associated with
the 10"5 excess cancer level will be excavated and treated; however,
the residue from biotreatment. will be contained in a lined RCRA
unit. Similarly, at Site D the biotreated material will be capped
after treatment.
Sites A, B, C, and D each considered risk in determining what soil
should be excavated. Industrial versus residential future-use
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scenarios caused risk numbers to vary from 10"5 to 10"6. Site D,
although selecting a 10"6 level, did not provide concurrent chemical-
specific cleanup levels.
VI. Involvement of PRPs and other Influences
PRP involvement at the Fund-lead sites was insignificant; however,
community interest was strong due to the existence of residences on
or near these sites. This interest was a strong factor in the
selection of destruction technologies. Biotreatment was found not
to be effective for Site A because of site-specific limitations and
costs equal to or exceeding incineration. Biotreatment was rejected
at Site B due to questionable effectiveness in local soils and the
length of time needed for remediation.
Biotreatment, an innovative technology, was selected in both
Enforcement-lead RODs, based on a full evaluation of the nine
evaluation criteria, consistent with Agency guidance. Given the
same degree of protectiveness as incineration alternatives,
biotreatment was significantly more cost effective, a requirement
of CERCLA, and appears to be an appropriate decision.
The presence of residents on or adjacent to the site influenced
remedy selection and the cleanup goals. Public comments on Sites
A and B affected remedy selection.
At Site D, the analytical method for determining which soils are
associated with a greater than 10"6 cancer risk level and exposure
assumptions for risk assessment, which could affect ultimate cleanup
levels, were influenced by the PRP. Each of these areas should be
re-evaluated.
D-41
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Appendix E
NCP Expectations For Treatment
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51422 Federal Regular / Vol. 53. No. 245 / Wednesday, December 21, 1988 / Proposed Rules
Section 300.430 Remedial
Investigation/Feasibility Study (RI/FS)
and Selection of Remedy.
Today EPA is proposing major
revisions to Subpart E to incorporate the
new requirements of the 1986 CERCLA
reauthohzation amendments into
existing procedures, and to reflect
program management principles EPA
intends to follow in order to promote the
efficiency and effectiveness of the
remedial response process. Chief among
these principles is a bias for action.
The 1988 CERCLA amendments
include a number of requirements
related to the remedial alternatives
development and remedy selection
process. Section 121 of the statute
retains the original CERCLA mandates
to select remedies that an protective of
human health and the environment and
that are cost-effective. In addition.
today's proposed revisions address the
new statutory requirement! for remedial
actions to attain the applicable or
relevant and appropriate requirements
of other Federal and State
environmental laws, the mandate to
utilize permanent solutions and
alternative treatment technologies or
resource recovery technologies to the
maximum extent practicable, and the
preference for remedies that employ
treatment that permanently and
significantly reduces the toxicity,
mobility, or volume of hazardous
substances, pollutants, or contaminants
as their principal element over those
that do not.
The overarching mandate of the
Superfund program is to protect human
health and the environment from the
current and potential threats posed by
uncontrolled hazardous waste sites.
This mandate applies to all remedial
actions and cannot be waived. The
mandate for remedies that protect
human health and the environment can
be fulfilled through a variety of means.
including the destruction, detoxification.
or immobilization of contamjnantf
through the application of treatment
technologies, and by controlling
exposure to contaminants through
engineering controls (such as
containment) and/or institutional
controls which prevent access to
contaminated areas.
The CERCLA amendments emphasize
achieving protection that will endure
over long periods of time by mandating
the use of permanent solutions to the
maximum extent practicable and by
specifying long-term effectiveness
factors that must be assessed under
section 121(b)(l) (A-G). The
amendments also express a clear
preference for achieving this protection
through the use of treatment
technologies as the principal element of
remedies. These provisions reflect the
belief that treatment that destroys or
reduces the hazardous properties of
contaminants (e.g., toxiciry or mobility)
frequently will be required to achieve
solutions that afford a high degree of
permanence. The highest degrees of
permanence are clearly afforded by
remedies that are not heavily reliant on
long-term operation and maintenance
following the completion of an
implemented action.
61 addition to these new mandates,
the amended CERCLA retained the
mandate for selecting remedies that are
cost-effective. Although cost-
effectiveness cannot be used to select a
nonprotective remedy, this mandate
does require EPA to evaluate closely the
costs required to implement and
maintain a remedy and to select
protective remedies whose costs are
proportionate to their overall
effectiveness. This mandate establishes
efficient use of resources as a standard
for Superfund remedial actions and
reflects Congress' intent to maximize the
use of the Fund across a large number of
sites. EPA intends to focus available
resources on selection of protective
remedies that provide reliable, effective
response over the long-term.
This combination of mandates (i.e.,
remedies that provide permanent
solutions to the maximum extent
practicable, the preference for treatment
as a principal element and cost-
effectiveness) creates dynamic tensions
for the Superfund program. In today's
proposal EPA extends some of the
fundamental features of the current NCP
in proposing to resolve these competing
goals through a process that examines
the characteristics of sites and
alternative approaches for remediating
the problems those sites pose. This
process evaluates alternative hazardous
waste management strategies using nine
criteria related to CERCLA's mandates
to determine advantages and
disadvantages of the various remedial
action alternatives. This analysis
identifies site-specific trade-offs
between options, and facilitates the risk
management decision which is the
fundamental nature of remedy selection
decisions at CERCLA sites. In balancing
trade-offs among options and selecting
the protective alternative which seems
to offer the best combination of
attributes in terms of the nine criteria
and is thus most appropriate for a given
site. EPA is exercising the discretion
granted by CERCLA to determine the
maximum extent to which permanent
solutions and treatment or resource
recovery technologies can be
practicably utilized in a cost-effective
manner.
EPA believes that the solutions that
are most appropriate for a given site wii
vary depending on the size, complexity.
and location of the site, the magnitude
of the threats posed, the timing of the
availability of suitable treatment
technologies, and the proximity of
human and environmental receptors.
among other factors. While the CERCLA
amendments strongly encourage the use
of treatment technologies in CERCLA
remedial actions, they allow for
discretion in dealing with site
circumstances and technological,
economic, and implementation
constraints that place practical
limitations on the use of treatment
technologies. Treatment is most likely to
be practicable for wastes that cannot be
reliably controlled in place, such as
liquids, highly mobile materials (e.g..
solvents), and high concentrations of
toxic compounds (e.g., several orders of
magnitude above levels that allow for
unrestricted use and unlimited
exposure). Treatment is less likely to be
practicable where sites have large
volumes of low concentrated material.
or where the waste is very difficult to
handle and treat (e.g.. mixed waste of
widely varying composition). Specific
situations that may limit the use of
treatment could include sites where: (1J
Treatment technologies are not
technically feasible or are not available
within a reasonable timeframe: (2) the
extraordinary size or complexity of a
site makes implementation of treatment
technologies impracticable: (3)
implementation of a treatment-based
remedy would result in greater overall
risk to human health and the
environment due to risks posed to
workers or the surrounding community
during implementation: or (4) severe
effects across environmental media
resulting from implementation would
occur. In addition, there are CERCLA
sites or portions of sites where the
concentrations of the wastes are at low
levels or are substantially immobile, and
where the wastes can be reliably
contained over a long period of time
through the use of engineering controls.
In these situations, treatment may not
always offer a sufficient degree of
increased permanence and long-term
protection to be cost-effective.
CERCLA sites are frequently complex
and involve a number of different
problems. EPA believes that it often will
be the case that the most appropriate
solution for a site will involve a
combination of methods of achieving
protection of human health and the
environment. Most frequently. EPA
expects that treatment of the principal
threats posed by a site, with priority
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Federal Register / Vol. 53. No. 245 / Wednesday, December 21. 1988 / Proposed Rules 51423
placed on treating highly toxic highly
mobile waste, will be combined with
engineering controls (such as
containment) for treatment residuals
and untreated waste.
As appropriate, institutional controls
such as water use and deed restrictions
may supplement engineering controls for
short- and long-term management to
prevent or limit exposure, to hazardous
substances, pollutants, or contaminants.
Institutional controls will be used
routinely to prevent exposures to
releases during the conduct of a
remedial investigation and feasibility
study, during remedial action
implementation, and as a supplement to
engineering controls designed to manage
wastes over time. The use of
institutional controls to restrict use or
access should not however, substitute
for active response measures (e.g.,
treatment and/or containment of source
material, restoration of ground waters to
their beneficial uses) as the sole remedy
unless such active measures an
determined not to be practicable, bated
on the balancing of trade-offs among
alternatives that is conducted during the
selection of remedy. These trade-offs.
based on the nine criteria, are identified
during the analysis of alternatives.
EPA recognizes that the approach
presented in today's proposed rule is not
the only approach possible for resolving
the competing goals and requirements of
Ihe Superfund program. Therefore, later
in this preamble EPA presents four
alternative approaches. Two of those
alternatives are site-specific balancing
approaches that while similar to the one
proposed in today's rule, differ primarily
in terms of how they organize the
evaluation criteria, and how they
incorporate the statutory requirements
to select remedies that are cost-effective
and that use permanent solutions and
treatment technologies to the maximum
extent practicable. The two additional
alternatives presented later represent
different approaches to remedy
selection, based on different views of
the goals and purposes of the Superfund
program. EPA solicits comments on
these four alternative approaches as
well as the approach presented in
today's proposed rule.
A. Program Management Principles
Today's proposal also includes
revisions to the 1985 NCP that are not
mandated by CERCLA. These revisions
reflect principles by which EPA intends
to manage the Superfund remedial
program. These principles stem from
experience gained over the first eight
years of the program. In managing
CERCLA sites. EPA must balance the
goal of definitively characterizing site
risks and analyzing alternative remedial
approaches for addressing those threats
in great detail, and the desire to
implement protective measures quickly.
EPA intends to balance these goals with
a bias for initiating response actions
necessary or appropriate to eliminate,
reduce, or control hazards posed by a
site, as early as possible. EPA will
promote the responsiveness and
efficiency of the Superfund program by
encouraging action prior to or
concurrent with conduct of an RI/FS as
information is sufficient to support
remedy selection. While the bias for
action promotes multiple actions of
limited scale, the program's ultimate
goal continues to be to implement final
remedies at sites.
Early action may be taken at a site via
enforcement or Fund-financed activities
taken under removal or remedial
authorities. In deciding between using
removal and remedial authorities, the
lead agency should consider (i) The
criteria and requirements for taking
removal actions in 1300.415 of today's
proposed rule; (ii) the statutory
limitations on removal actions and the
criteria for waiving those limitations;
(iii) the availability of resources: and the
(ivj urgency of the site problem. Specific
actions that may be taken under
removal authorities include emergency
action, non-time-critical removals, and
expedited response actions. A
discussion of these activities is included
in the i 300.415 preamble section. Early
actions using remedial authorities are
initiated as operable units.
The Superfund program has long
permitted remedial actions to be staged
through multiple operable units.
Operable units an discrete actions that
comprise incremental steps toward the
final remedy. Operable units may be
actions that completely address a
geographical portion of a stte or a
specific site problem (e.g., drums and
tanks, contaminated ground water) or
the entire site. Operable units include
interim actions (e.g.. pumping and
treating of ground water to retard plume
migration) that must be followed by
subsequent actions which fully address
the scope of the problem (e.g.. final
ground water operable unit that defines
the remediation level and restoration
timeframe). Such operable units may be
taken in response to a pressing problem
that will worsen if unaddressed. or
because there is an opportunity to
undertake a limited action that will
achieve significant risk reduction
quickly.
The appropriateness of dividing
remedial actions into operable units is
determined by considering the
interrelationship of site problems and
the need or desire to initiate actions
quickly. To the degree that site problems
an; interrelated (e.g.. contaminated soils
and ground water), it may be most
appropriate to address the problems
together. However, where problems are
reasonably severable. phased responses
implemented through a sequence of
operable units may promote more rapid
risk reduction.
Related to the bias for action is the
principle of streamlining, which EPA
intends to emphasize in managing the
Superfund program as a whole and in
conducting individual remedial action
projects. On a project-specific basis.
recommendations to ensure that the RI/
FS and remedy selection process is
conducted as effectively and efficiently
as possible include:
a. Focusing the remedial analysis to
collect only additional data needed to
develop and evaluate alternatives and
to support design;
b. Focusing the alternative
development and screening step to
identify an appropriate number of
potentially effective and implementable
alternatives to be analyzed in detail.
Typically, a limited number of
alternatives will be evaluated that are
focused to the scope of the response
action planned:
c. Tailoring the level of detail of the
analysis of the nine evaluation criteria
(set below) to the scope and complexity
of the action. The analysis for an
operable unit may well be lees rigorous
than that for a comprehensive remedial
action designed to address all site
problems;
d. Tailoring selection and
documentation of the remedy based on
the limited scop* or complexity of the
site problem and remedy. In particular.
operable units initiating interim
remedies may require less complex
justifications because they are limited
actions that will only require minimum
j
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Appendix F
Treatment Versus Containment
Comparisons
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OSWER Directive 9835.13
Seven site types were evaluated in detail to determine why
containment was selected over treatment. Twenty-six RODs were
reviewed - 14 were for Enforcement-lead sites and 12 were for Fund-
lead sites. The other nine site types were analyzed, but not in
detail, because: treatment was selected for all sites in that site
type (Battery/Lead, Dioxin, Solvents, and Wood Preserving);
containment was expected in that site type (Asbestos,
Radioactive/Mixed Waste, Mining and Municipal Landfill); or, no
comparison of Fund-lead versus Enforcement-lead could be conducted
(Munitions). Described below are the findings as to why
containment was chosen over treatment.
Industrial Landfill Sites
Of the five Enforcement-lead sites where some action was
taken, four RODs (80%) chose containment and one chose treatment.
Of the RODs for the 13 Fund-lead sites where some action was taken,
10 chose treatment and three (23%) chose containment. Both
treatment and containment RODs were reviewed.
The seven sites choosing containment, both Fund- and
Enforcement-lead, were reviewed to determine if there were any
principal threats at the sites that should have been treated, or
if site characteristics or other factors justified the selection
of an exclusively containment alternative.
The results of the review showed the following explanations
for why containment was chosen. Some sites have more than one
reason supporting their decision.
F-l
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OSWER Directive 9835.13
Size (Greater
RI/FS than Acceptable No Hot Cost
Site Lead 100.000 yd3) Risk Levels Spots F>*-*inr
Site IP xx
Site 2 P x x
Site 3 P x x
Site 4 P x x
Site 5 F x x
Site 6 F x x x
Site 7 . F x x
RODs at five of the seven sites (three Enforcement-lead RI/FSs
and two Fund-lead RI/FSs) selected containment due to the
considerable size of the site (greater than 100,000 yd3 of
contaminated material) , and the associated difficulties in
implementation posed by this size. Other factors included risk
levels for source material within an acceptable risk range (three
Enforcement-lead, two Fund-lead), no hot spots identified (two
Enforcement-lead), and Cost factors (three Fund-lead).
Of the RODs for the five sites that noted that the risk levels
were within an acceptable range, one had a soil risk of 5 x 10"6,
one had a worse case dermal exposure risk of 5 x 10"6, and a third
had an on-site air risk of 6.2 x 10"7. A fourth stated that the
risk assessment indicated low exposure, and the fifth stated there
was no current risk.
For the sites listing cost as a decision factor, one chose a
$3 million cap and dike remedy over a $100 million incineration
remedy. Another Fund-lead site which listed cost as an explanation
of its choice of containment considered treatment alternatives, but
only incineration was considered implementable due to the diversity
of waste. The cost associated with incineration at this site was
$214 million with a 30 year implementation period, or $486 million
F-2
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OSWER Directive 9835.13
over 10 years. The containment treatment chosen for this site (cap
and off-site disposal) is projected to cost $28.7 million. The
third site listing cost as a factor selected a soil cover with a
projected cost of $1.6 million. This Fund-lead site considered,
but never projected costs, for treatment remedies.
*
A survey of the RODs selecting treatment for Industrial
Landfills showed that six Fund-lead remedies treated the entire
contaminated volume ranging from 90 to 48,000 yd3. Three Fund-
lead remedies selected partial treatment for the most contaminated
wastes at the site. Each of these three sites treated
approximately 30,000 yd3, out of total volumes ranging from 100,000
to 535,000 yd3. The tenth ROD, signed in 1988, was amended in 1989
to treat the entire waste volume.
The one Enforcement-lead site that selected treatment treated
the entire contaminated volume (180,000 yd3). Judicial review is
presently occurring on this site.
All RODs in this category provided sufficient rational for
selecting containment over treatment.
Metal Sites
The percentage of RODs selecting containment compared to
treatment for Metal sites were similar for Fund-lead and
Enforcement-lead sites: Enforcement-lead, one of four (25%)
selected containment; Fund-lead, one of five (20%) selected
containment. For both leads, most RODs choose treatment. However,
because treatment generally may be expected for metal sites, the
two containment RODs (one Enforcement- and one Fund-lead RI/FS)
were reviewed.
F-3
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OSWER Directive 9835.13
Both sites appeared to have unique characteristics that made
treatment technically infeasible. The soils at the Fund-lead site
were mixed with large quantities of debris. This mixture does not
lend itself to solidification, which normally would be expected
treatment at metal contaminated sites.
The remedy at the one Enforcement-lead site was sludge
application and vegetation on the steep slopes (in excess of 20%
grade) around the site, in order to reduce surface water run-off.
In-situ chemical precipitation was ruled out due to expected poor
performance and unreliability. The ROD for the Enforcement-lead
site did not provide sufficient documentation or rationale as to
why containment was selected over treatment.
Metals/Orqanics Sites
For Enforcement-lead sites, the RODs at four of 10 (40%) chose
containment. For the Fund-lead sites, four of 30 (13%) chose
containment. All the Fund-lead and Enforcement-lead sites where
RODs chose containment were reviewed to determine why treatment was
not chosen.
In general, treatment at Metals/Organics sites is complicated
due to the technical uncertainties of treating wastes that are a
mixtures of organic and inorganic contaminants. The decisions to
contain wastes at these eight sites were based upon varying
rationales.
F-4
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OSWER Directive 9835.13
Previous No Significant
RI/FS Removal Contamination Technical
Site Lead Action Low Risk Feasibility
Site 1 P x
Site 2 P x
Site 3 P x
Site 4 F x
Site 5 F x
site 6. F x
Site 7 F x
Site 8 P x
One Fund-lead site eliminated soil washing because there was
questionable effectiveness. At another Fund-lead site, the size
of the site (over one million cubic yards) , the two to three
additional years necessary to conduct treatability testing, and the
unavailability of equipment justified selecting containment rather
than treatment. A third Fund-lead site eliminated treatment due
to low volume and the low risk levels associated with contaminated
soil. The fourth Fund-lead site had already had a major source-
control removal action.
Two Enforcement-lead sites also had already had major source
control actions which limited the extent and level of contamination
remaining. A third Enforcement-lead site had limited health risks,
therefore justifying the use of containment. The baseline risk
levels were not, however, provided in the ROD. At the remaining
Enforcement-lead site, the major contaminant in the soil is lead.
This site had some VOCs above background in soils, and VOCs in
ground water, but the soils had lead levels above health based
levels. Since lead cannot be destroyed, the primary options are
containment or stabilization. These two approaches both reduce
mobility; however, the treatment process (stabilization) results
in significant volume increases. It was decided, therefore, that
F-5
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OSWER Directive 9835.13
the benefits of treatment (the reduction in mobility) are not
expected to offset the volumetric increase in contaminated
material.
Three of the eight RODs (two Fund-lead, one Enforcement-lead)
in the Metals/Organics category that were reviewed did not provide
sufficient documentation or rationale to clearly demonstrate why
containment was selected over treatment.
Organic Sites
For Enforcement-lead sites, three of 10 (30%) chose
containment. For Fund-lead sites, one of five (20%) chose
containment. The four containment RODs (one Fund-lead, and three
Enforcement-lead) were reviewed.
No Significant
RI/FS Technical Contamination
Site Lead Volume Feasibility_ Low Risk
Site IPX X
Site 2 P X X
Site 3 P X
Site 4 F X
One Fund-lead site, and one Enforcement-lead site had
relatively low residual levels of contamination. The Fund-lead
site had a previous source control removal action and baseline
risks are in the 10"5 to 10"6 range, which is in the acceptable risk
range. The Enforcement-lead site had contaminants in the 10"7 to
10"9 range in most site areas and one area with contaminants in the
10"5 to 10"7 range, which is in the acceptable risk range.
F-6
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OSWER Directive 9835.13
The technical infeasibility of treatment was a major reason
why containment was selected at the two other Enforcement-lead
sites. In both cases the large volume of wastes (52,000 yd3) were
considered to be very difficult to reliably treat, because of the
high levels of organics in the soils. Several technologies were
considered including bioremediation, solidification, and
vitrification. Bioremediation was not selected due to the very
high organic concentrations. Likewise, solidification was
determined to be incompatible with wastes at the site.
Vitrification was not selected because of the lack of long term
demonstration and the frequency of electrode burnout. In addition,
treatment equipment for such large waste volumes was not considered
to be available.
Three of the four RODs in the Organics category (All
Enforcement-lead) did not provide sufficient documentation or
rationale as to why containment was selected over treatment.
PCB Sites
Enforcement-lead sites chose treatment 100% of the time (six
sites). For Fund-lead sites, one of fifteen (7%) chose
containment. No lead-related differences were noted for PCB sites
in selecting remedial action. Even though only one ROD selected
containment, treatment is a readily available option for PCB
contaminated sites, so it was decided to analyze this containment
ROD.
*
For the Fund-lead site where containment was selected,
treatment options were considered but rejected for two reasons:
public concerns about incineration and the desire for the future
land use to be residential; treatability study results that showed
F-7
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OSWER Directive 9835.13
that dechlorination was impractical because of the soil's clay
content. In this case, therefore, both public concerns, and
technical infeasibility drove the selection of containment.
The ROD for the site where containment was selected provided
sufficient rationale for selecting containment over treatment.
Pesticide Sites
Enforcement-lead sites chose containment at. one of the two
sites where action was taken (33%). At the Fund-lead sites,
containment was chosen in two of the seven (29%) cases where action
was taken. The three containment RODs were reviewed because
treatment is the expected alternative for pesticide contaminated
sites.
For the one Enforcement-lead site, the decision to contain
wastes was predominantly a function of technical feasibility.
Treatment was ruled out because of difficulties in expeditiously
implementing this remedial alternative and because treatment was
determined to be ineffective in controlling short-term risks. At
this site the quantity of dioxin containing waste (70,000 yd3) to
be treated would require approximately six years of capacity of a
specially permitted unit.
For one of the Fund-lead sites where containment was selected,
the remedy consisted of excavation and off-site disposal in a
permitted RCRA Subtitle C landfill of approximately 4050 yd3 of
wastes. This decision was based primarily on cost effectiveness.
The cost differential was $2.1 million for containment and $7.6
million for on-site incineration. The current risk is estimated
at 7xlO"5. It was determined that either containment or treatment
F-8
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OSWER Directive 9835.13
of soils with contamination at this level would have similar,
effective long-term results, but treatment would have a much higher
cost.
At the other Fund-lead site, the presence of arsenic, in
addition to the expected organics, would have required the use of
an unproven innovative technology train approach which was not
expected to be effective on impermeable soils. Incineration would
remove"the organic contaminants from the soil; however, the most
toxic contaminant, arsenic, would continue to be present in
residual ash/soil following treatment. In addition, the continued
land use of this airport facility necessitates the minimization of
short-term impacts.
The Enforcement-lead ROD in the Pesticides category did not
provide sufficient documentation or rationale to clearly
demonstrate why containment was selected over treatment.
Plating Sites
RODs at Enforcement-lead sites chose containment in one out
of the three (33%) of the cases. Fund-lead sites chose treatment
100% of the time (five sites).
The Enforcement-lead site selected containment over treatment
as the most practical and cost-effective remedy based on the risks
involved, and the protectiveness offered by the selected
alternative. The baseline risks provided by the region were
stated as 10"* .for soils, and protectiveness referred to the
handling of the asbestos containerized waste in the landfill. In
addition, this site contained over 132,000 yd3 of material. The
cost for incineration versus containment was $40.3 versus $6.7
million.
F-9
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