NCD991278953_19880628_National Starch & Chemical Corp._FRBCERCLA FS_Draft Feasibility Study Report-OCR

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@ INTERNATIONAL
TECHNOLOGY CORPORATION
D R A F T
FEASIBILITY STUDY REPORT
NATIONAL STARCH AND CHEMICAL CORPORATION SITE
CEDAR SPRINGS ROAD PLANT
SALISBURY, NORTH CAROLINA
Prepared By
IT Corporation
Knoxville, Tennessee
June 1988
Revision No. O
Approved:~ £·~ ~ amManager, iTCporation
Approve
Date:
Date:
Date: .7iioe 28 I 988 '
CEE1363COV
06/28/88 F3
Regional Office
312 Directors Drive• Knoxville. Tennessee 37923. 615-690-3211
IT Corporation is a wholly owned subsidiary of International Technology Corporation
I /
MEMORANDUM
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION IV
345 COURTLAND STREET
ATLANTA, GEORGIA 30365
DATE: JUN 2 9 ISSlil ',
SUBJECT:
FROM:
National Starch Feasibility Study
Salisbury, North Carolina
Giezelle s. Bennett A--Af3
Enforcement Project Managetf (!J 1
1 1988
TO: National Starch FS Review Team:
Doug Lair, ESD
Wade Knight, ESD
Gail Vanderhoogt, Water
Chuck Morgan, ESE
CLee~Crosby, -NC Sold -&-Hazardous Waste
Ries Collier, US Fish & Wildlife
Cody Jackson, ATSDR
Attached is the draft Feasibility Study Report for the National
Starch Site in Salisbury, NC. Please submit comments to me no later
than July 15, 1988.
If you have any questions, please give me a call at [phone].
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rn INTERNATIONAL TECHNOLOGY CORPORATION
tEASIBILITY STUDY REPORT
NATIONAL STARCH AND CHEMICAL CORPORATION SITE
CEDAR SPRINGS ROAD PLANT
SALISBURY, NORTH CAROLINA
Approved:~ £
Pr am Manager,
Approved·
Prepared By
IT Corporation
Knoxville, Tennessee
June 1988
Revision No. O
Date:
Date:
Date: iZ«oe 28 /!;}BB '
Regional Ot!ice
312 Directors Drive• Knoxville. Tennessee 37923 • 615-690-3211
CEE 1363COV IT Corporation JS a wholly owned subsidiary of International Technology Corporation
06128188 n
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CONTENTS
1.0 INTRODUCTION
2.0 SUMMA.RY OF THE REMEDIA.L INVESTIGA.TION
2. 1 Ground Water
2.2 Surface Water
2.3 Sediment
2.4 Soil
3.0 GROUND WA.TER MODELING
4.0 PUBLIC HEA.LTH EVA.LUA.TION
4. 1 Introduction
4.2 Exposure A.ssessment
4.3 Chemicals of Concern in Ground Water
4.4 Ground Water Criteria (A.RA.Rs) at the Site Boundary
4.5 Discussion
5.0 DEVELOPMENT OF REMEDIA.L A.CTION A.LTERNA.TIVES
5. 1 Development of General Response/Remedial
Technologies
5.2 Screening Remedial Technologies/Process Options
5.3 Development of Remedial A.ction A.lternatives
6.0 DETA.ILED A.NA.LYSES OF REMEDIA.L A.CTION A.LTERNA.TIVES
6. 1 A.lternative 1 -No-A.ction
6.2 A.lternative 2 -Off-Site Disposal
6.3 A.lternative 3 -Ground Water Extraction and Discharge
to POTW
6.4 A.lternative 4 -Ground Water Extraction and Treatment
6.5 A.lternative 5 -Ground Water Extraction and Treatment
in Existing Lagoon System
7.0 COMPA.RA.TIVE A.NA.LYSIS OF A.LTERNA.TIVES A.ND RECOMMENDA.TION OF
SELECTED A.LTERNA.TIVE
7. 1 Comparative A.nalysis
7.2 Recommended A.lternative
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Number
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,TIIBLES
t
Comparison of Level of Metals Detected in the Sediment
of Creeks on or lldjacent to the National Starch and
Chemical Corporation Site, Salisbury, North Carolina
with Typical Background Levels
Site-related Carcinogens of Potential Concern at
National Starch and Chemical Corporation Site,
Salisbury, North Carolina
Site-related Noncarcinogens of Potential Concern at
National Starch and Chemical Corporation Site,
Salisbury, North Carolina
Ground Water Criteria (IIRI\Rs) for Potential Carcinogens
at the NSCC Site Boundary
Ground Water Criteria (IIRIIRs) for Potential Non-
carcinogens at the NSCC Site Boundary
National Starch and.Chemical Corporation RI/FS
Development of Remedial Technologies for Ground Water
Contamination
National Starch and Chemical Corporation RI/FS Screening
Control Technologies for Ground Water Contamination
Summary of lllternative llnalyses for National Starch
Chemical Corporation
FIGURES
Regional Map, Plant, Trench llrea, and Surrounding llrea
Pathway/Receptor Model for NSCC Site, Salisbury, NC
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1.0 INTRODUCTION
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In April 1985, the U.S. Environmental Protection Agency (EPA) proposed the
National Starch and Chemical Corporation (NSCC) Cedar Springs Road Site in
Salisbury, North Carolina for inclusion on the National Priority List (NPL)
under the authority of the Comprehensive Environmental Response, Compensation,
and Liability Act (CERCLA). However, the rulemaking on the site is not final,
and the site continues to remain only proposed for the NPL.
A remedial investigation (RI) was conducted on the site from December 1986
through January 1988 by NSCC. The final RI report was submitted in June
1988. This feasibility study (FS) is based on the findings of the RI and
recommends a remedial action to address contamination resulting from the
site. This remedial action will protect the public health and environment.
The FS is presented in seven sections with Section 1.0 being the introduc-
tion. Section 2.0, Summary of ·the Remedial Investigation, serves to summarize
the findings of the RI and to bridge the RI conclusions. into the framework for
the FS. Separate subsections will address ground water, surface water,
sediment, and soil contamination. Section 3.0, Ground Water Modeling,
includes the description and purpose of using a site-wide ground water model
to simulate ground water flow and contaminant transport. Section 4.0, Public
Health Evaluation, discusses the impact of current conditions and acceptable
criteria for concentrations of chemicals in ground water· at the property
line. These criteria are based on the toxicity, mobility, migration pathway,
persistence in the environment, site-specific characteristics, and on existing
regulations and literature that establish current regulatory thresholds.
Section 5.0, Development of Remedial Action Alternatives, represents a summary
of technologies that may be applicable in addressing contamination present on
site. The listed technologies are rejected or retained based on technical and
cost merits for use as component technologies for site remedial efforts. The
technologies are grouped into operable units that are evaluated in final
fashion, which are included in Section 6.0. Final evaluation includes
technical feasibility, cost, institutional requirements, public health
protection, and environmental protection. From these potential remedial
actions, a r_emedial action can be selected for implementation at the site.
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EPA will prepare a record of decision (ROD) for this site based on the final
approved FS. A remedial action design will be prepared for the selected
alternative. After completing the remedial action design and securing EPA
approval, implementation of the selected alternative can begin.
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2.0 SUMMARY OF THE REMEDIAL INVESTIGATION
2. 1 GROUND WATER
The Phase I RI activities involved the installation of 17 monitoring wells,
NS-01 through NS-17. Wells NS-01 through NS-14 were shallow wells that
sampled water in the saprolite, and Wells NS-15, NS-16, and NS-17 were deep
wells that sampled water from the bedrock aquifer. These 17 wells were
sampled in April and July 1987. The first set of samples were analyzed for
all Hazardous Substance List (HSL) parameters as well as pH, conductivity,
chloride, total dissolved solids (TDS), cyanide, and phenols. The second
round of samples were analyzed for these same parameters minus pesticides and
polychlorinated biphenyls (PCBs).
In the Phase II RI activities, six additional wells were installed in August
1987, NS-01A (to replace NS-01 that was dry) and NS-21 through NS-25. Wells
NS-01A, NS-22, and NS-23 are shallow wells; Wells NS-21, NS-24, and NS-25 are
deep or bedrock wells (see Figure 2-1).
Twenty-nine organics were detected at least once in the 38 ground water
samples collected. No pesticides/PCBs were detected in any ground water
samples. The HSL analytical program includes 125 organics, 23 metals,
cyanide, and phenols.
Shallow and deep monitoring wells monitor two distinct geologic units that are
interconnected. The presence of analytical parameters in the shallow well is
likely to indicate that analyte is also in the deep aquifer. To a lesser
extent, the converse may also hold true.
Three areas were targeted for ground water investigation at this site: the
wastewater treatment lagoons, the area just west of the plant between the
plant and trench area (where soil from wastewater lagoon retrofitting was
stockpiled and aerated by NSCC), and the trench area.
No ground water contamination associated with wastewater treatment lagoons was
found.
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Monitoring wells were situated on the east, west, and south sides of the soil
stockpile area. Given the close proximity of the trench area and the soil
stockpile area, it is difficult to definitely discern between any ground water
impacts caused by these respective sources. However, data from the soil
stockpile area indicates no impact on ground water quality.
The trench area consists of ~pproximately 5 acres (Figure 2-1) that was
routinely used from 1970 to 1979 for disposal of wastewaters generated by
NSCC's Cedar Springs Road and Lumber Street plants. The wastewater typically
was a low pH salt solution that contained trace levels of organics and
metals. A more complete discussion of the waste characteristics is included
in the RI report. Trenches were routinely dug 3-feet wide by 8-feet deep by
100-to 300-feet long and filled with wastewater .. Subsequent trenches were
dug as trench percolation rates decreased significantly.
Ground water contamination has occurred as a result of the trench area, but
contamination remains on the NSCC property. The ground water contaminant
plume appears to be moving at approximately 75 feet per year. Acetone appears
to be the most mobile contaminant with the other organics and metal plumes
moving much slower. Specific conductance and chloride appear to be good
parameters to monitor plume movement. Contaminant isopleths are included in
the RI report.
Acetone is the most widespread organic present in the ground water because it
is the most soluble. The concentration gradient drops dramatically from the
trench area to downgradient wells. Well NS-22 is regarded as the most down-
gradient well and is roughly 100 feet from the NSCC property line; this well
shows acetone at 22 parts per billion (ppb). The absence of a monitoring well
directly west of the trench area prevents a definite determination of how far
west the acetone contamination has migrated, but it is inferred that the con-
tamination is moving at the same rate to the west, north, and southwest.
The wastewaters placed in the trench were highly acidic salt (chloride)
solutions. The chloride and specific conductance plumes are very similar and
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show both parameters to have steep concentration gradients with contamination
trends toward the west with ground water flow. Outer perimeter wells show
little, if any, contamination.
Smaller plumes exist for 1,2-dichloropropane, 4-nitrophenol, 1, 1,2-trichloro-
ethane, xylene, 1,2-dichloroethane, and bis (2-chloroethyl). This is either
because of their lower water solubilities, higher partitioning coefficients,
or of their lower concentration in the wastewaters placed in the trench
area. Generally, these plumes remain close to the trench area with little
westerly migration. Some of the organics may be present in only select wells
indicating sporadic usage by NSCC or not typically present in wastewaters
placed in the trench area. These organics are characterized by slower
movement in ground water, no prevalence across the entire trench area, steep
concentration gradients, and small contamination plumes.
Contamination plumes also exist for three metals: cadmium, beryllium, and
manganese. The cadmium and· beryllium concentrations are quite low with
cadmium levels near the drinking water standard just downgradient of the
trench area. The manganese concentrations are quite high at these same
points, but drop off dramatically.
Ground water contamination has not migrated off NSCC property, although it is
present at the site. Contaminants,. mostly in the form of volatile and base
neutral organics, are present in the· saprolite and bedrock aquifers. The
contaminant plume is well-defined and has steep concentration gradients
emitting from the trench area.
Ground water within the bedrock aquifer will have a horizontal and vertical
flow component that is influenced by surface topography and hydrostatic
pressures. However, the fractures and sheeting planes will have a major
influence on the direction of ground water flow. Because fractures tend to be
concentrated in topographic lows, the ground water will tend to flow
downgradient toward these areas where it can discharge, thereby creating
creeks and streams.
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For these reasons, it is reasonable to expect the surface water tributaries·
that form the boundaries of the NSCC property to provide protection against
the movement of ground water contaminants into adjoining properties.
2.2 SURFACE WATER
In the Phase I RI activities, samples were collected at six points. Three
additional samples were collected in the Phase II RI, all from Grants Creek.
In the Phase I activities, no acid extractable organics or pesticides/PCBs
were found in the surface water samples. Cyanide and phenol concentrations
were typically at less than detectable levels.
Surface water sampling at SW-1 in March 1987 showed 1,2-dichloroethane at 1400
ppb (Figure 2-1). Subsequent sampling by EPA in June 1987 on this same
tributary verified the presence of 1,2-dichloroethane. However, EPA sampled
this eastern tributary at two additional points downstream and did not find
any organics. EPA concluded, and IT concurs, that 1,2-dichloroethane is not
migrating off site, and there is no inorganic contamination of this tributary.
No organics were found in the tributary to the southwest of the trench area.
Similarly, no organics were found in the tributary to the northwest of the
trench area. Cyanide and phenol concentrations were at or below detection
limits. Metal concentrations are not significantly different from the
background point.
In the Phase II activities, sampling of Grants Creek was proposed because of
the organics found in the sediment of the northwest and southwest
tributaries. No organics were found in any of these three water samples.
Cyanide and phenol levels are at or below detection limits. Metal
concentrations are not significantly different from the respective background
point.
Except for the one observation of 1,2-dichloroethane on the eastern tributary,
surface water is uncontaminated. Even for this tributary, the 1,2-dichloro-
ethane rapidly dissipates and falls to below detectable levels well before the
water exits the NSCC property. No organics were found in surface water in the
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southwest tributary, the northwest tributary, or Grants Creek. Metal concen-
trations do not change significantly from background levels. Consequently,
surface water bodies bordering the NSCC property are not being affected by the
trench area.
2.3 SEDIMENT
The sediment at SE-1 shows 1,2-dichloroethane at 18 µg/kg, which is expected
because this compound was found in the water at this point. EPA sampling also
shows 1,2-dichloroethane in the sediment just upstream in SE-1; however, as in
the case of the water, the 1,2-dichloroethane is absent from two downstream
EPA samples on this same tributary. No other organics were found at SE-1
except for acetone at 44 ppb. Acetone is found at eight out of nine sediment
sampling points, including two background points.
Acetone was found in the northwest tributary sediments at 65 and 33 ppb. No
other organics were found other than acetone.
Sediment samples in the southwest tributary show acetone .at 42 ppb, 50 ppb,
and nor.detectable. At these points, butyl benzylphthalate and bis(2-ethyl
hexyl)phthalate were found at concentrations as high as 3400 ppb. However, it
is believed these sediment samples were contaminated by surgical latex gloves
worn by sampling personnel. Consequently, the only organic present in these
sediment samples is acetone (as observed in other sediment samples).
Acetone is also present in Grants Creek sediment samples, including the
bac~ground sample, suggesting other potential upgradient sources of acetone.
Acetone is present in Grants Creek sediments at 116 and 18 µg/kg with the
background point showing 29 µg/kg.
Therefore, the only sediment contamination found is acetone at concentrations
ranging from 18 to 116 µg/kg in the northwest and southwest tributaries and
1,2-dichloroethane at SE-1.
2.4 SOIL
The boundaries of the trench area are known and the waste disposal practices
fairly well documented. The soil sampling program consisted of eight soil
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samples collected within or near the trench area to better understand the
levels and types of residuals remaining in the soil matrix. The volume of
soil above the saturation zone containing these residuals is estimated to be
greater than 100,000 cubic yards.
The soil in the trench area contains organics that are typically found in the
ground water immediately adjacent to the trench area. These organics are
assumed to be somewhat representative of the trace organics present in the
wastewaters placed in the trenches. The number of organics detected in ground
water is less than the number in soil samples because of the higher detection
levels in soil analysis.
Soil composite samples were collected from five boreholes from the trench area
to determine if HSL parameters were present in the unsaturated zone. The
samples represent a composite over Oto 15 feet from each of the five
boreholes.
The following volatile organic parameters were identified in the soil borehole
samples; concentration ranges are also shown:
Concentration Detection
Parameters (µg/kg dry wt) Levels
Methyl chloride ND-9 5
Acetone ND-3300 7
1,2-Dichloroethane ND-820 7
2-Butanone ND-18 15
Toluene ND-210 7
Ethylbenzene ND-48 7
Total xylenes ND-250 7
ND= Nondetectable
Three discrete soil samples were collected from monitoring well boreholes as
split spoon samples were being taken continuously. Parameters identified are
listed below along with concentration ranges:
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Parameters
l\cetone
1,2-Dichloroethane
Toluene
1,2-Dichloropropane
Bis(2-chloroethyl)ether
ND= Nondetectable
Concentration
(µg/kg dry wt)
2100 -30998
ND-210
ND-620
ND-72
ND-1100
Detection
Levels
500
50
50
50
330
No acid extractable or pesticides were found. Cyanide and phenol levels were
nondetectable.
Contaminants in the soil vadose zone are essentially nonmobile and are subject
to natural decay due to volatilization, biodegradation, and some minimal
leaching from precipitation in filtration. The only way that these
contaminants can manifest themselves to be a threat to the public health or
environment is through ground water transport after reaching the saturated
zone.
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3.0 GROUND WATER MODELING
In order to effectively evaluate the selected remedial alternative involving
ground water at the NSCC site, a model of the hydrologic system is desirable
due to the complexity of the hydrogeologic environment and the wide variety of
potential performance options available. Since ground water contaminants are
of concern, a particulate transport model is also required. The model .being
prepared for the site consists of a finite difference numerical ground water
flow model and a ground ·water particulate transport model.
The model allows grid spaces that can be varied to focus upon areas of
greatest interest within the model. l\lso, both the ground water flow and
transport phases can be modeled in a layered or three dimensional manner. The
model will permit multiple confined or unconfined aquifer layers and can
simulate a wide variety of external effects including rainfall recharge,
evapotranspiration, and ground water conductance into or out of the model.
The ground water flow model uses the finite difference numerical method with
several possible solution algorithims. The transport model evaluates the
effects of convection, dispersion, and chemical reactions.
accomplished using a statistical random walk technique for
Mass transport is
dispersion effects
and the particle-in-a-cell technique for convection effects.
The models will be used to evaluate the selected remedial alternative. This
will be accomplished by a simulating performance options in the model, such as
flow rates and well locations, and identifying their impact upon ground water
contaminant concentrations. Results from the model.will not be used to supply
absolute numbers for evaluation purposes. Instead, they will be used to
provide information on the effectiveness of one option compared to another.
The NSCC model consists of two layers. The upper layer represents the
saprolite aquifer while the lower layer represents the bedrock aquifer. The
aquifers are interconnected and the model assumes that a confining layer is
not present.
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Grid spacing in the model varied to concentrate node positions around the
trench area. Layer thicknesses and ground water elevations have been varied
to simulate actual site conditions. Initial aquifer permeability values have
been obtained using the results from slug tests conducted as part of the RI
and from values presented by Groves (1976). The original values will be
adjusted within a reasonable range until acceptable results are obtained. In
addition, stream nodes identifying the eastern, northeast, and southeast
tributaries and Grants creek are included in the model. Ground water
discharge estimates into the creeks have been estimated using gauging station
records for Grants Creek (Goddard 1963), and the relationship of ground water
discharge being equal to that amount of stream flow that is equaled or
exceeded 70 percent of the time (Groves 1976). Knowing the amount of ground
water discharge into the streams also provides an estimate of ground water
recharge from rainfall infiltration. Other data sources relied upon to
estimate initial conditions include: the USGS topographic maps of the area, a
report on commercial granites in North Carolina which describes various basic
bedrock structural characteristics (Council 1954), and a conceptualized
description of .the hydrogeologic character of the Piedmont region by LeGrand
(1967).
Model calibration is initially being accomplished using a model that covers an
area of approximately 92 acres. This model is centered over the trench
area. The hydrogeologic character of this models has been simplified to
permit the rapid measuring of the model's response to specific parameters as
they are varied. This technique permits establishment of aquifer parameters,
which may be difficult to determine in the main model due to the large number
of variables. In addition, this model can be used to demonstrate detailed
effects of potential remedial options at the trench area because of the finer
grid spacing.
After acceptable model parameters have been established, conditions will be
simulated until the hydrologic system of the model has stabilized, resulting
in constant ground water elevations. At this point, contaminant particulates
will be added and the transport model calibrated until contaminant
concentrations are similar to current concentrations. Potential performance
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options will then be tested to determine their impact on the flow system and
contaminant concentrations.
The model can be refined and the extraction rate finalized as additional
hydrogeologic data are obtained during a pilot test or while implementing the
selected remedial alternative; the data will be used to adjust the remedial
action as conditions change in the field. This function of the model will aid
in minimizing remedial action costs and maximizing public safety since a range
of.ground water extraction scenarios can be simulated before implementation.
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4.0 PUBLIC HEALTH EVALUATION
4. 1 INTRODUCTION
This public health evaluation is designed to address the potential long-term
threats to public health and the environment resulting from the presence of
chemicals at the NSCC site. The contents of this risk assessment are based on
"Guidance on Feasibility Studies Under CERCLA" (EPA, 1985). The use of the
more recent review draft document, "Guidance for Conducting Remedial Investi-
gations and Feasibility Studies Under CERCLA (EPA, 1988) is not appropriate in
the conduct of this assessment because the preliminary hazard assessment as
part of the RI was complete prior to the release of the new draft guidance.
This risk assessment will review the potential exposure pathways that are
relevant to this site in its current condition and the potential for human
exposure at some time in the future. It will also discuss site-specific
criteria that are relevant to chemicals that are potentially present in
environmental media at the site boundary.
Long-term public health risks will be estimated based on potential exposure to
chemicals in the air, soil, surface water, and sediments in the adjacent
streams and ground water. Potential threat to the environment will be
addressed by considering the likelihood of exposure of endangered species.
The site was the subject of an in-depth environmental study, and the results
of this study were presented in the RI. The site investigation confirmed the
presence of 11 carcinogens and 14 noncarcinogens in ground water adjacent to
the former trench area. Evaluation of this same group of chemicals in a
second group of wells at varying distances from the former trench area clearly
demonstrates that chemical migration is being impeded. Six carcinogens and
three noncarcinogens were identified in ground water from this outer group of
wells at levels that would be of potential concern if direct consumption of
this water occurs from these wells over the course of a lifetime. These nine
chemicals are considered to be the more toxic and more mobile chemicals on the
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site and, as such, are considered appropriate indicator chemicals for the more
detailed site assessment. The approach to selecting indicator chemicals in
this more detailed study has been changed from that used in the RI to address
the unusual site conditions that might impact lateral migration.
4.2 EXPOSURE ASSESSMENT
The purpose of this section is to describe the exposure pathways related to
chemical transport and the potential exposure of receptors. The primary
purpose of an exposure assessment is to determine the concentration levels
over time and space in each environmental media where human and environmental
receptors may come in contact with the chemicals of concern. The three
components of an exposure assessment are:
• Pathway analysis
• Identification of exposure scenarios
• Estimation of exposure.
Each exposure pathway, such as surface runoff or fugitive dust emission, is
characterized using the elements listed above and the database presented in
the RI.· A generalized pathway receptor model is shown schematically in Figure
4-1. The potential exposure pathways subsequently described are as follows:
Air
Volatile emissions
-Particulate emissions
• Surface water
-Transport of dissolved chemicals in runoff and recharge into
Grants Creek and the unnamed streams on the site
• Sediment
Transport of adsorbed chemicals in sediment carried by surface
runoff
• Ground water
-Vertical leakage
-Off-site transport.
I. The assumptions and parameterr; used for each pathway and all relevant calcu-
lations will be presented. ·Grants Creek and an unnamed stream make up the
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AIR RECEPTOR
(VAPORS)
SITE RECEPTOR
RELATED
CHEMICALS
AIR
(FUGITIVE RECEPTOR
DUST)
SOIL
SURFACE RECEPTOR
WATER
SEDIMENT -RECEPTOR
GROUND
WATER
RECEPTOR
FIGURE 4-1. PATHWAY /RECEPTOR MODEL FOR NSCC SITE, SALISBURY, NC
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southern and western boundaries of the site. The potential for future migra-
tion of chemicals from the site into these water bodies will be addressed.
4.2. 1 ~ir
Inhalation exposure to chemicals at or close to a hazardous waste site can
result from:
• Release of volatile compounds
Presence of chemicals adsorbed to fugitive dust particles.
Liquid waste was poured into trenches and allowed to percolate into the
ground. ~s trenches were deactivated, they were backfilled with soil. In
this·way, the chemical-bearing liquid wastes were confined below the soil
surface. The soil matrix is predominantly a sandy clay to clayey saprolite.
The depth of the volatile chemicals below grade is likely to prevent the
extensive release of vapors. This conclusion is borne out by the lack of any
detectable vapors at any point on the site.
The methodology used to deactivate each trench would likely preclude extensive
presence of chemicals in the surface soil. Thus, any fugitive dust resulting
from this area of the site is not likely to contain levels of site-related
organic chemicals adsorbed to the particles that could have a significant
health impact. In addition, fugitive dust is minimized by relatively dense
scrub-like vegetation over most of the former trench area.
With the disposal practices used at this site, there is little likelihood of
exposure to site-related chemicals being carried with fugitive dust. Further-
more, the potential for exposure to volatile components is likely to be
negligible. Because chemicals. are not likely to be present in surface soils,
the air exposure pathway is not considered relevant for this site in terms of
potential risk to the public.
No reports could be identified that would indicate that the area surrounding
the NSCC property is the natural habitat of any species included on the North
Carolina List of Endangered or Threatened Species. But should any of these
endangered or threatened species be present in the area, the air exposure
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pathway is not considered relevant because chemicals are not likely to be
present in surface soils.
4.2.2 Surface Water
The local topography results in the surface runoff from the former trench area
being directed toward the southwest. This runoff drains into an unnamed creek
along the southern side of the site. The unnamed creek drains in turn to
Grants Creek which flows north as it passes along the western boundary of the
site.
The only detectable organic constituent in surface water, 1,2-dichloroethane,
was found in one sample (SW-1) collected during the site investigation from a
stream running across the northeast corner of the site. It is known that 1,2-
dichloroethane was previously stored in the northeast corner of the plant
area. Thus, the detectable levels in the stream possibly.result from an
isolated leak or spill.
A more recent sampling effort that was conducted by EPA in June 1987 resulted
in the collection of water from four different locations on this stream,
including a spot close to the point where it leaves the NSCC property. An
additional location was selected some distance downgradient outside the site
boundary. No organics were detected in these locations downgradient from
sampling point SW-1. The EPA sample (NS-W4) that was collected in the same
general area as sample SW-1 did have detectable levels of 1,2-dichloroethane,
but an upgradient sample (NS-W3) did not indicate any detectable levels of
this compound. It is reasonable to conclude that the 1,2-dichloroethane
detected at SW-1 (March 1987) and NS-W4 (June 1987) is confined to an isolated
area of the creek that is on NSCC property.
Employees at the NSCC plant have no direct contact with this stream in the
course of their routine job functions. In addition there is no evidence of
off-site migration based on downgradient stream samples. Thus, the presence
of 1,2-dichloroethane has no direct impact on public health.
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The apparent localization of 1,2-dichloroethane to a short section of the
creek on NSCC property is not vie~ed as a potential threat to any endangered
species on the North Carolina List of Endangered or Threatened Species. No
reports could be identified that would indicate the area surrounding the NSCC
property is the natural habitat of any species included on the North Carolina
List.
4,2.3 Sediment
A total of three volatile organic compounds and base/neutral extractables were
identified in sediment collected from the streams or creeks on or adjacent to
the NSCC property. Acetone was detected at levels up to 116 ppb in eight of
the nine sediment samples collected. This included detectable levels in
sediment collected from Grants Creek at a point upgradient from the confluence
of the southwest tributary and Grants Creek. This would suggest that the
acetone present in these creek sediments at levels that exceed the detection
level by one to one and a half orders of magnitude may not be site related.
Regardless of the source of the material, .its presence is at such low levels
that it would not have any impact on public health even if exposure occurred
over a lifetime.
To place this in perspective, it has been estimated that in a residential
exposure scenario, average consumption of dirt over the course of a lifetime
from all sources is on the order of 10 mg/day (Paustenbach, 1987). Using the
worst case unrealistic assumption that a person receives their entire daily
intake of dirt from a single source (creek sediment containing the highest
concentration of acetone) the maximum intake of acetone for a person working
or a child playing in the creek would be:
Daily intake (mg/day) = Concentration (µg/kg) X Amount Consumed (kg/day)
1000 (ug/mg)
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= 116 (µg/kg) X 0.00001 (kg/day)
1000
= 1. 16 X 10-6 mg/day
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A daily intake of 1. 16 X 10-6 mg acetone would be considered insignificant
based on an estimated acceptable chronic daily intake of 0. 1 mg/kg/day (EPA,
1986).
Methylene chloride was detected in two sediment samples at about the
analytical limits of detection. Levels this close to the limits of detection
can be analytical artifacts. Similarly 1,2-dichloroethane was detected in one
sediment sample at twice the analytical detection limit. However, using
similar unrealistic calculations to that described above, estimated potential
daily intakes for methylene chloride and 1,2-dichloroethane are 8 X 10-8
mg/day and 1.8 X 10-7 mg/day, respectively. These levels are too low to
result in any potential health consequence. There is a natural background
cancer incidence of approximately one in four. Thus, over a lifetime it would
be anticipated that one out of four persons will develop cancer. Excess
cancer risk is expressed in terms of.an increase in the cancer incidence above
background. A 10-5 excess cancer risk represents a change in detectable
cancers from 25,000 per 100,000 population to 25,001 per 100,000 population.
For potential carcinogens, excess cancer risk is estimated based on the cancer
potency factor and some estimate of daily intake over a lifetime. Using EPA
cancer potency factors, the respective excess cancer risks associated with
consuming these hypothetical amounts daily over an entire lifespan are 8.6 X
10-12 for methylene chloride and 2.3 X 10-10 for 1,2-dichloroethane.
Di-n-butylphthalate was detected in one sediment sample taken from Grants
Creek upgradient from the confluence with the southwest tributary. This
sample is upgradient from the NSCC site and the level reported was at
approximately the analytical detection limit. Because of the location of this
single sample, it is most likely an analytical artifact or sampling-induced
error.
Bis(2-ethylhexyl) phthalate was observed in the three sediment samples
collected from the southwest tributary. Concentrations ranged from 2.7 to 3.4
parts per million (ppm). Based on the unrealistic exposure scenario described
above, daily intake would be at a maximum 3.4 X 10-5 mg/day. Using the cancer
potency factor provided in the Superfund Public Health Evaluation Manual
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(SPHEM) (EPA, 1986) and using an unrealistic exposure scenario which assumes
daily intake for a lifetime, the estimated excess cancer risk would be about
3.3 X 10-lO_
Phthalates are ubiquitous chemicals in the environment because of their
extensive use in plastics. They are also used in many laboratory materials.
Presence of the phthalates observed in the site investigation is attributed to
sample error because of sampling personnel wearing surgical gloves when
handling sediment samples from the southwest tributary.
A number of different metals were detected in the sediments collected from the
creeks associated with the NSCC site. Levels of the different metals were
found to be representative of typical background levels (Table 4-1) and are
not considered to have resulted from any significant contribution from
disposal practices at the NSCC site .
Overall, the presence of low levels of chemicals in the sediments of creeks
either on or adjacent to NSCC property will not result in any potential health
concerns even if a person were exposed to these sediments daily for their
entire lifespan.
The presence of low levels of several organic chemicals in the sediments of
creeks on NSCC property is not viewed as a potential threat to any endangered
species on the North Carolina List of Endangered or Threatened Species. No
reports could be identified that would indicate the area surrounding the NSCC
property is the natural habitat of any species included on the North Carolina
List.
4.2.4 Ground Water
There are two primary pathways when characterizing the potential for chemical
migration in ground water:
• Vertical migration of chemicals toward bedrock which is influenced by
the physiochemical properties of the chemicals and the rate of
vertical percolation of water
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Table 4-1. Comparison of Level of Metals Detected in the Sediment of
Creeks on or Adjacent to the National Starch and Chemical Corporation Site,
Salisbury, North Carolina with Typical Background Levels
Metal
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Iron
Lead
Manganese
Nickel
Selenium
Thallium
Vanadium
Zinc
Range of
Values Detected
(mg/kg)
0. 9 -20
11. 2 -108
ND
ND
5.7 -274
8 -41
2. 6 -58
3270 -38,800
3.1-9.9
64.9 -1230
4.4
ND
ND
9. 9 -150
2.8 -43
aMean (Range) from Borden (1966).
ND= Not detected.
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Typical Background
Levelsa
(mg/kg)
6(0.1-4)
500 (100 -3000)
6 ( 0. 1 -40)
0.06 (0.01 -0.7)
100 (5 -3000)
8 (1 -40)
20 (2 -100)
38,000 (7000 -550,000)
10 (2 -200)
850 (100 -4000)
40 ( 10 -1000)
0.2 (0.01 -2)
5(0.1-12)
100 (20 -500)
50 (10 -300)
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• Lateral movement of chemicals in ground water as characterized by a
plume with a moving front edge that will advance at a rate that is
based on the flow of ground water and the inherent properties of the
soil to retard the migration of specific chemicals.
Lateral movement of ground water through the saprolite and fractured bedrock
is likely to carry chemicals toward the site boundary. As long as the
chemicals remain within the NSCC site boundary, there is no potential risk to
public health or the environment. However, movement of a chemical plume I' across the site boundary results in the perception of a potential adverse
impact on public health. This potential would only be realized if ground
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water were extracted for direct or indirect human consumption.
At this time it is estimated that no site-related chemical has migrated to the
boundary of the NSCC property. However, even with the retardation factors
associated with chemicals at this site, it is plausible that at some time in
the future some chemicals may reach that line of demarcation. As chemicals
·migrate toward the property line significant attenuation is likely to occur as
a result of retardation and dilution. Additionally, the southwest, northwest,
and Grants Creek tributaries form aquifer discontinuities that will serve to
impede plume movement off site. However, because NSCC cannot control the use
of ground water beyond their site boundary, consideration must be given to
acceptable levels of chemicals that may potentially leave .the site in ground
water.
Ground water is typically used as a source of drinking water in rural areas of
the United States. Taking a health protective approach it may be assumed that
a well will be drilled at the site boundary, and ground water drawn from this
well will be used as a source of drinking water. Based on the local
topography this is an unlikely scenario for the placement-of drinking water
wells. However, this will ensure that water at the site boundary is suitable
for drinking water while maintaining an adequate level of health protection.
In the following sections the relevance of the levels of site-related
chemicals to the potential for off-site migration will be discussed. In
addition, it will be clearly demonstrated that the use of drinking water
standards at the site boundary will afford adequate protection for any
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drinking water wells placed beyond the tract of land controlled by NSCC.
Where appropriate drinking water standards do not exist, applicable or
relevant and appropriate requirements (ARARs) will be developed that would
afford at least the same level of health protection as that afforded by
drinking water standards.
4.3 CHEMICALS OF CONCERN IN GROUND WATER
High levels of a number of organic and inorganic chemicals have been detected
in ground water collected from wells in the saprolite and from wells in the
bedrock. Although current information shows that off-site migration has not
9 occurred, the potential does exist that this may arise at some time in the
future.
No drinking water wells will be constructed on NSCC property in the
foreseeable future; however, NSCC has no control on ground water usage
Ground water flow is predominantly to the west.
beyond
The their property line.
City of Salisbury has municipal water available to residents located north,
east, and south of the plant. Currently, there are no residences west of the
plant across Grants Creek. If site-related chemica!.s exceed ·site boundary ,.
thresholds, their concentrations need to be sufficiently low to ensure the
long-term protection of public health. An initial screening of the data was
carried out to determine those chemicals of greatest potential concern based
on their detected levels in ground water.
To carry out this screening it was assumed that a drinking water well would be
placed at the location of the highest concentration of each chemical and that
human receptors would be exposed throughout a lifetime to drinking water
containing this level of chemical. In building this hypothetical exposure
scenario it was assumed that these human receptors would consume 2 liters of
water per day.
Chemicals were divided into carcinogens and noncarcinogens because estimates
of the hazard associated with a chemical are usually based on their potential
to cause cancer. In general, the presence of known or suspected human
~carcinogens in ground water will receive greater weight than the presence of
noncarcinogens unless it can be clearly demonstrated that the levels of a
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given noncarcinogenic chemical will have a greater potential impact than the
levels of a carcinogen.
4.3.1. Selection of Potential Carcinogens
There is a natural background cancer incidence of approximately one in four·.
Thus, over a lifetime it would be anticipated that one out of four persons
will develop cancer. Excess cancer risk is expressed in terms of an increase
in the cancer incidence above background. A 10-4 excess cancer risk
represents a change in detectable cancer from 2500 per 10,000 population to
2501 per 10,000 population. A 10-6 excess cancer risk represents a change in
detectable cancer from 250,000 per 1,000,000 population to 250,001 per
1,000,000 population. For potential· carcinogens, excess cancer risk is
estimated based on the cancer potency factor and some estimate of daily intake
over a lifetime.
The National Primary Drinking Water Regulations (EPA, 1987) state that the
target reference risk range for carcinogens in drinking water is 10-4 to
10"'6. Actual examples of upper bound lifetime cancer risk estimates ( 10-5 )
for a number of volatile organic chemicals is provided in the regulations.
EPA clearly states that they consider this to be a safe level and protective
of public health and that it is supported by the concept expressed by the
World Health Organization (WHO) 1984 Guidelines for Drinking Water Quality
where a 10-5 guideline was provided.
· The selection of carcinogenic indicator chemicals is based on their maximum
detected concentration on the site and the risks associated with a human
receptor drinking 2 liters of this water daily over a lifetime. Selecting
those chemicals that might pose some potential risk in a purely hypothetical
exposure scenario ensures that the more significant chemicals will also be
addressed in terms of relevant acceptable concentrations at the site
boundary. Using the guidance provided by EPA in the National Primary Drinking
Water Regulations (EPA, 1987), chemicals that exceed a 10-5 excess cancer risk
based on the maximum concentration observed at this site are selected (Table
4-2). Although not meeting the 10-5 criteria, other chemicals have been
included for reference purposes only based on comments made by EPA.
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Table 4-2. Site-related Carcinogens of Potential Concern at
National Starch and Chemical Corporation Site,
Salisbury, North.Carolina
I
I' Compound
1,2-Dichloroethane
I Bis(2-chloroethyl)ether
Arsenic
Vinyl chloride :I 1, 1-Dichloroethylene
Chloroform
1, 1,2-Trichloroethane
I Bromodichloromethane
Benzene
Trichloroethylene
Methylene chloride
Maximum
Observed
Cone.
(µg/1)
350,000
14,000
310
90
11
49
11
7
8
10
8
Estimated Worst Case
Worst Case Excess
Intakea CPFb Cancer
(mg/kg/day) (mg/kg/day)-1 Riske
1.00E+01 9. 10E-02 9.10E-01
4.00E-01 1. 10E+OO 4.40E-01
8.86E-03 1. 50E+OO 1 . 33E-02
2.57E-03 2.30E+OO 5.91E-03
3.14E-04 5.80E-01 1 . 82E-04
1.40E-03 8. 10E-02 1. 13E-04
3.14E-04 5.73E-02 1. 80E-05
2.00E-04 8. 10E-02 1 . 62E-05
2.29E-04 5.20E-02 1. 19E-05
2.86E-04 1. 10E-02 3. 14E-06
2.29E-04 7.50E-03 1. 71E-06
Number
Exceeding
Detection
Limitd
18
7
13
3
1
4
2
1
1
1
2
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aThe estimated worst case intake does not represent any real exposure scenario at the
site. It is based on a 70 kg person drinking 2 liters of water per day for their entire
life from the monitoring well containing the ·maximum observed concentration of a
chemical. This hypothetical exposure scenar.io is used to rank relative toxicity based on
the inherent toxicity and the maximum detected concentration of each chemical. This
assumption assists in identifying those carcinogens that have the greatest potential
bto pose a hazard with frequent exposure over a number of years.
CPF or Cancer Potency Factors were obtained from the SPHEM (EPA, 1986).
cworst case excess cancer risk is derived from the equation ECR = CPF X Dose
Where: ECR = excess.cancer risk, CPF = cancer potency factor, and Dose= estimated
worst case intake. I drndicates the number of samples out of 38 that exceed the analytical detection limit for
that chemical. ,,
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Nine chemicals were initially identified as being of potential concern. Their
presence in ground water were at levels that could result in an excess cancer
risk of greater than 10-5 to a hypothetical human receptor drinking water
containing this on-site maximal level. In the process of selecting indicator
chemicals, the SPHEM (EPA, 1986) recognizes the need to base the selection of
indicator chemicals on relative potential toxicity, mobility, and ·prevalence
of detection on the site. Because dense brines containing various organic
solvents were disposed in the trench area, the use of downgradient wells to
select the more mobile chemicals may not adequately address the long-term
considerations associated with the NSCC site. It is, however, appropriate to
use frequency of detection as a parameter for selecting indicator chemicals.
A total of 38 separate ground water samples were taken in two sampling
efforts. In most instances, identified carcinogens occu·rred in multiple
samples; however, benzene, bromodichloromethane, and 1, 1-dichloroethylene each
occurred in a single sample (i.e. less than 5 percent of the samples). In
each of these cases the concentration detected was very close to the
analytical detection limit. Any migration of these chemicals away from the
point of original detection will result in a degree of attenuation and
dilution that will render detection impossible using currently available
analytical techniques. In addition, the uncertainties that are associated
with detecting a chemical in a single sample at or close to the detection
limit provide further justification for removing them as indicator chemicals
for establishing any ground water cleanup that might be associated with a
site. Thus, for the purposes of defining ARARs at the site boundary, the
carcinogenic indicator chemicals are:
• 1,2-dichloroethane
• Bis(2-chloroethyl) ether
• Arsenic
• Vinyl chloride
• Chloroform
• 1, 1,2-Trichloroethane .
4.3.2 Selection of Noncarcinogens
In selecting noncarcinogenic indicator chemicals, the inherent toxicity of a
chemical, its prevalence, and its mobility should all be taken into
consideration. Because potential exposure of human receptors to chemicals in
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ground water could last a lifetime, any screening process that is used to
identify chemicals of concern should take into account the possible chronic
toxicity of those chemicals. An approach that is recommended by the SPHEM
(EPA, 1986) is to create a Hazard Index (HI) for each chemical. The HI is a
ratio of the estimated potential intake of that chemical to a reference dose
(RfD) or acceptable intake for chronic exposures (AIC).
For many chemicals AICs or RfDs have been developed by EPA and have been
published in SPHEM (EPA, 1986). Revised or newly prepared RfDs have been made
publicly available (since May 1988) through a EPA database known as Integrated
Risk Information System (IRIS). Where AICs or RfDs are not available in the
SPHEM (EPA, 1986), IRIS has been consulted indirectly to determine the
availability of an RfD from that source. In the case of 4-nitrophenol, no RfD
or AIC is apparently available. Limited acute toxicity data indicates that
4-nitrophenol is about twice as toxic as phenol. An estimate of an AIC/RfD
can be made by using the RfD for phenol and using an uncertainty factor of ten
to provide a margin of health protection.
The selection of noncarcinogenic indicator chemicals is based on their maximum
detected concentration on the site and acceptable daily intakes ass.ociated
with a human receptor drinking 2 liters of this water daily over a lifetime.
Ratios greater than unity show that the estimated intake exceeds a level that
may be considered safe for chronic intake. Selecting those chemicals that
might pose a potential long-term hazard in a purely hypothetical exposure
scenario ensures that the more significant chemicals _will also be addressed in
terms of relevant acceptable concentrations at the site boundary. The level
of pd-~ential concern. is based on the estimated hazard index. Chemicals that
exceed a hazard index of unity based on the maximum concentration observed at
this site are selected (Table 4-3). Other chemicals that have hazard indices
less than unity are included in the table for reference purposes only based on
co!llllents made by EPA.
A total of 12 chemicals were initially identified as being of potential
concern because of their presence in ground water at levels that result in a
hazard index that exceeded unity. In the process of selecting indicator
chemicals, the SPHEM (EPA, 1986) recognizes the need to base the selection of
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Table 4-3. Site-related Noncarcinogens of Potential Concern at the
National Starch and Chemical Corporation Site,
Salisbury, North Carolina
Maximum Estimated
Observed Worst Case !UC Worst Case
Cone. Intakea or RfD Hazard
Compound ( ~g/1) (mg/kg/day) (mg/kg/day)-1 lndexb
1,2-Dichloropropane 29,000 8.29E-01 1. 71E-04 4845.4
Manganese 1,380,000 3.94E+01 2.20E-01 179 .2
4-Nitrophenol 13,000 3.71E-01 1 .OOE-02 37. 1
Acetone 89,000 2.54E+OO 1.00E-01 25.4
-Nickel 5190 1. 48E-O 1 1. OOE-02 14.8
Cadmium 114 3.26E-03 2.90E-04 11.2
Xylene (mixed) 3800 1.09E-01 1 . OOE-02 10.9
Beryllium 120 3.43E-03 5.00E-04 6.9
Chromium (as Cr(VI)) 554 1.58E-02 5.00E-03 3.2
Selenium 274 7.83E-03 3.00E-03 2.6
Zinc 14900 4.26E-01 2. 10E-01 2.0
Barium 2290 6.54E-02 5. 10E-02 1.3
Toluene 6000 1. 71E-01 3.00E-01 0.6
Ethyl benzene 1500 4.29E-02 1 .OOE-01 0.4
Sourcec
MCLG
HEA
d
RfD
HEA
HEA
HEA
RfD
HEA
HEA
HEA
HEA
RfD
RfD
aThe estimated worst case intake does not represent any real exposure scenario at the
site. It is based on a 70 kg person drinking 2 liters of water per day for their entire
life from the monitoring well containing the maximum observed concentration of a
chemical. This hypothetical exposure scenario is used to rank relative toxicity based on
the inherent toxicity and the maximum detected concentration of each chemical. This
assumption assists in identifying those noncarcinogens that have the greatest
potential to pose a hazard with frequent exposure over a number of years.
bHazard index is derived from the equation HI = Dose/Reference Dose
Where: HI= hazard index, Dose= estimated worst case intake, and Reference Does=
acceptable intake for chronic exposure.
CHEA= Health Effects Assessment document prepared by Environmental Criteria and
~ssessment Office (ECAO), EPA, 1984.
Derived by using the RfD for phenol and using an additional safety factor to address the
known higher acute toxicity of 4-nitrophenol.
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indicator chemicals on relative potential toxicity, mobility, and prevalence
of detection on the site.
A total of 38 separate ground water samples were taken in two sampling
efforts. In all instances, identified noncarcinogens occurred in multiple
samples. For the purposes of defining ARARs at the site boundary, the non-
carcinogenic indicator chemicals are:
• 1,2-dichloropropane
• Manganese
• 4-nitrophenol
• Acetone
• Nickel
• Cadmium
• Xylenes (mixed)
• Beryllium
• Chromium (as Cr(VI))
• Selenium
• Zinc
• Barium .
4.4 GROUND WATER CRITERIA (ARARs) AT THE SITE BOUNDARY
There is no evidence that would suggest that any site-related chemicals have
crossed the NSCC property boundary. However, the potential exists for
chemicals to migrate beyond the perimeter of the NSCC property at some time in
the future. From all that is known of the site conditions and the identified
indicator chemicals, it would be reasonable· to assume that migration of these
chemicals may be impeded as a result of adsorption to the soil matrix. Even
with these caveats, ground water modeling should be evaluated to determine
whether concentrations of chemicals that might occur at the property line at
•sometime in the future could have an impact on public health.
About two thirds of the chemicals of concern have primary or secondary
drinking water standards. To ensure adequate protection of public health,
these standards (where available) are adopted as the ground water criteria or
ARAR at the site boundary using the assumption that drinking water could be
collected at this point.
For those chemicals of concern where no published drinking water standard or
proposed standard exists, an ARAR has been developed. A health protective
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approach has been used where possible; however, where the calculated ARAR is
below the best analytical methodology available, the analytical detection
limit is used as the ARAR.
The derived values are based on the assumption that a human receptor with a
body weight of 70 kg consumes 2 liters of water per day from a single source
and that they drink this water for 50 percent of their lifespan. A lifespan
is considered to be 70 years.
Thus, for carcinogens, the ARAR is based on the equation:
Where:
ARAR = ECR X BW X Wf
CPF XV
ARAR = applicable or·relevant and appropriate requirement (µg/L)
UCR = unit cancer risk (10-5 )
BW =bodyweight (70 kg)
Wf = conversion factor for milligrams to micrograms (1000 µg/mg)
CPF = cancer potency factor (mg/kg/day)-1
V = volume of drinking water consumed (L/day).
For noncarcinogens, the ARAR is based on the equation:
Where:
ARAR = ADI X BW X Wf
V
ARAR = applicable or relevant and appropriate requirement (µg/L)
ADI= acceptable daily intake (using an RfD or AIC (mg/kg/day)
BW: body weight (70 kg)
Wf = conversion factor for milligrams to micrograms (1000 µg/mg)
V = volume of drinking water consumed per day (L/day).
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The recommended ARARs for ground water at the NSCC site boundary are presented
in Tables 4-4 and 4-5. Exceptions to standards or calculated values are noted
where appropriate.
4. 5 DISCUSSION
Data collected during the RI and evaluated at that time from the perspective
of potential, immediate, and substantial risk have been reexamined with a view
to determining the long-term risks associated with the NSCC site. In this
public health evaluation, exposure pathways for human receptors were
considered. Potential exposure of endangered or threatened species was also
considered.
Site-related chemicals in the soil are believed to be confined largely to the
deeper soil levels in the trench area. In the ground water, site-related
chemicals occur both beneath the former trench area and hydrogeologically
downgradient from this area.
Potential exposure via the airborne pathway to chemical vapors was not
considered to be probable based on the lack of detectable vapors at this
site. In addition it is concluded that exposure to chemical-bearing fugitive
dust is unlikely because of the probable depth of chemical-bearing soil and
the coverage of the trench area with dense plant growth.
Only one chemical (1,2-dichloroethane) was identified above detection limits
in surface water. Based on the location of these detectable quantities within
the NSCC site boundary, it was concluded that the levels would not have an
impact on public health. Furthermore, because the 1,2-dichloroethane was
found in an area of the site that is not routinely used by employees, the
potential for routine occupational exposure was considered remote.
Three volatile organics, acetone, methylene chloride, and 1,2-dichloroethane,
and a number of metals were identified in sediments from stream or creek beds
associated with the site. The levels of organics were sufficiently low that,
based on a health protective exposure scenario, no potential public health
hazard was identified. The levels of metals were compared to generic back-
ground levels of metals in soils. Values were determined to be comparable to
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Table 4-4. Ground Water Criteria (ARARs) for
Potential Carcinogens at the NSCC Site Boundary
ARAR
Compound CAS No. (µg/L)
Arsenic 7440-38-2 50
Benzene 71-43-2 5
Bis(2-chloroethyl)ether 111-44-4 10
Bromodichloromethane 75-27-4 100
Chloroform 67-66-3 100
1,2-Dichloroethane 107-06-2 5
1, 1-Dichloroethylene 75-34-4 7
Methylene chloride 75-09-2 100
1, 1,2-Trichloroethane 79-00-5 200
Trichloroethylene 79-01-6 60
Vinyl Chloride 75-01-4 2
Source
NPDWSa
NPDWSa
b
NPDWsa,c
NPDWsa,c
NPDWSa,c
NPDWSa
d
NPDWSe
d
NPDWSa
aNational Primary Drinking Water Standards (NPDWS) Maximum Contaminant
Level ( MCL) ( 40 CFR 14 1 ) .
bset as low as feasible based on analytical methodology.
cMCL listed is for total trihalomethanes.
dARAR = ECR X BW X Wf
CPF XV
Where:
ARAR
ECR
BW
Wf
CPF
V
=
=
=
=
=
=
applicable or relevant ~nd appropriate requirement (µg/L)
excess cancer risk (10-)
body weight (70 kg)
conversion factor for milligrams t9 micrograms (1000 µg/mg)
cancer potency factor (mg/kg/day)-
volume of drinking water consumed (2 liters/day). It is
assumed that a human receptor will drink 2 liters of water per
day from a single source during 50 percent of their natural
lifespan. This is equivalent to 1 liter per day over the
entire lifespan.
Note: Calculated ARARs are rounded to one significant figure.
eMCL listed is for 1, 1, 1-trichloroethane.
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Compound
Acetone
Barium
Beryllium
Cadmium
Table 4-5. Ground Water Criteria (ARARs) for
Noncarcinogens at the NSCC Site Boundary
ARAR
CAS No. (µg/L)
67-64-1 7000
7440-39-3 1000
7440-41-7 36
7440-43-9 10
Chromium (as Cr(VI)) 7440-47-3 50
1,2-Dichloropropane 78-8.7-5 6
Ethyl benzene 100-41-4 7000
Manganese 7439-96-5 50
Nickel 7440-02-0 700
4-Nitrophenol 100-02-7 700
Selenium 7882-49-2 10
Toluene 108-88-3 2000
Xylene (mixed) 1330-20-7 440
Zinc 7440-66-6 5000
aARAR = ADI X BW X Wf
V
Where:
Source
a
NPDWSb
a
NPDWSb
NPDWSb
NPDWSc
a
NPDWSd
a
a
NPDWSd
NPDWSc
NPDWSc
NPDWSd
ARAR = applicable or relevant and appropriate requirement (µg/L)
ADI = acceptable daily intake [using an RfD or AIC (mg/kg/day)
SW= body weight (70 kg)
Wf = conversion factor for milligrams to micrograms (1000 µg/mg)
V = volume of drinking water consumed (2 liters/day). It is assumed
that a human receptor will drink 2 liters of water per day from
a single source during 50 percent of their natural life-
·span. This is equivalent to 1 liter per day over the
entire lifespan.
bNational Primary Drinking Water Standard (NPDWS) Maximum Contaminant
Level (MCL) (40CFR141).
cNational Primary Drinking Water Standard (NPDWS) Proposed Maximum
Contaminant Level Goal (Proposed MCLG) (40 CFR 141).
dsecondary Drinking Water Standard (40 CFR 143).
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background and thus were not attributed to disposal practices at the NSCC
site.
Three phthalates were also identified at low levels in the creek sediments.
These chemicals are widely used in plastics including surgical gloves and
disposable laboratory supplies. The detection of these chemicals in creek
sediment, including background samples, was attributed to contamination during
handling. As such, there is no perceived potential public health risk.
The highest levels of site-related chemicals were found in ground water in the
immediate vicinity of the trench area; however, lower levels of several
organic and inorganic constituents were also found to have migrated some
distance from the trench area over a period of up to 16 years. At this time
there is no evident or planned use of ground water at the site boundary
hydrologically downgradient from the trench area; however, in the interests of
ensuring adequate protection of public health in the future, the potential use
of this water must be considered.
A number of potentially carcinogenic and noncarcinogenic chemicals were
selected as indicator chemicals in the ground water medium. Selection of
indicator chemicals was based on perceived risk associated with the
hypothetical and unrealistic scenario of daily consumption of water containing
the highest concentration of the indicator chemical detected on the NSCC
site. The other parameter used in indicator selection was prevalence in the
ground water samples collected. Three chemicals were found to have
concentrations close to the detection limits, and their occurrence in each
' case was limited to a solitary sample: As such, these were not considered to
be representative indicator chemicals and were left out of consideration when
developing ground water criteria at the site boundary.
Adequate protection is provided against all chemicals that are less prevalent
by addressing those chemicals that have the highest concentrations and great-
est evidence of on-site presence, and ensuring that there is no potential risk
to public health or the environment from those chemicals. Ground water cri-
teria (ARARs) at the property boundary for indicator chemicals were developed
as described in Section 4.4. Where available primary and secondary drinking
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water standards are used as ARARs. When drinking water standards were not
available a health protective approach was used to develop ARARs. All ARARs
are based on the assumption that drinking water wells will be placed at the
property boundary. This is a very conservative health protective approach
that may not be necessary based on the location of the site and current land
use.
No details could be obtained on the presence of endangered or threatened
species in the environs of the NSCC site. However, the potential for exposure
of any wild or domestic animals is limited because the chemicals detected on
this site are predominantly contained within the soil and ground water
matrices and, at this time, there is no evidence of the ground water
recharging chemicals to water that might be used by animals.
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5.0 DEVELOPMENT OF REMEDIAL ACTION ALTERNATIVES
The purpose of this section is to develop remedial action alternatives that
adequately meet the goals for protecting human health and the environment.
Based on the discussion presented in Section 4.0, the media of primary concern
at the site is ground water. Therefore, the remedial action alternatives will
be formulated by developing remedial action objectives aimed at protecting
ground water receptors and the environment. The surface water/sediment and
air routes of exposure do not require remediation.
Although contaminants are present in the soil, the only way that these
contaminants can threaten, if at all, the public health or environment is
through ground water. Consequently, soil remediation is not necessary if
ground water is to be monitored and controlled.
The remedial action objectives for this site are:
Human Health
• Prevent ingestion of water, at the site boundary, having carcinogens
in excess of the ARAR concentrations listed in Table 4-3.
Prevent ingestion of water, at the site boundary, having
noncarcinogens in excess of the ARAR concentrations listed in Table
4-4.
Environmental Protection
• Protect off-site ground water quality from exceeding ARAR
concentrations.
The remainder of this section presents the general response action that will
satisfy the remedial action objectives followed by a list of technology types
and process options for each general response action. Each of the
technology/process options is then screened to determine its applicability,
given the site conditions. After the screening process, the technologies are
combined into feasible alternatives for further evaluation in Section 6.0.
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The development of general response actions is based on the remedial action
objectives identified above. The assemblage of remedial technologies
associated with each general response action for the media of concern are
presented in Table 5-1. The process options presented in this table do not
represent the entire list of options available, only those that were judged to
be implementable based on information from the Remedial Investigation Report.
5.2 SCREENING REMEDIAL TECHNOLOGIES/PROCESS OPTIONS
The purpose of this section is to screen the identified remedial action
technologies and their associated process options. A process option refers to
specific processes within a technology type; for instance, a chemical
treatment technology would include process options such as precipitation, ion
exchange, and oxidation. These process options are evaluated for
effectiveness, implementability, and cost to determine the applicability of
each process option given the site characteristics. The following is a
discussion of the remedial technologies and process options along with the
basis for which each option was judged to be retained or dismissed.
5.2.1 No Action
The no-action alternative would leave contaminated ground water and soils in
place. Chemicals may possibly migrate to the NSCC site boundary or be attenu-
ated in the subsurface. Based on current.flow rates, it may be several years
before the ground water contaminant plume would reach the property boundary.
Concentration levels would reduce over time because of simple dilution,
adsorption, and biodegradation; however, ARARs are exceeded. Potential
results of implementing this alternative include continued ground water
contamination and restricted on-site ground water use. The National Oil and
Hazardous Substances Contingency Plan (NCP) requires the no-action alternative
to be considered during the FS. It is therefore retained for further
evaluation.
5.2.2 Institutional Actions
Fencing
Fencing is normally recommended as a method to control the direct contact of
humans or animals with a contaminated source. Because the surface soils do
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liil --

-
--

-
-

-
--

-

-
--Table 5-1. National Starch and'Chemical Corporation RI/FS
Development of Remedial Technologies for Ground Water Contamination
Environmental
Media Remedial Action Objectives
Ground water For human health:
Prevent ingestion at the site boundary
of water having carcinogens in excess of
ARARs concentration I isted in Table 4-3
Prevent ingestion at the site boundary
of water having noncarc_i nogens in excess
of ARARs concentration I isted in Table 4-4
For environmental protection:
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Protect off-site ground water qua I ity
from exceeding ARARs concentrations
General Response Actions
No action
Institutional options:
Access restriction
Monitoring
Containment actions:
Containment
Collection/treatment actions:
Collection/treatment dis-
charge/in situ ground water
treatment
Remedial Technology Types
No action
Institutional options:
Deed restrictions
Alternative water supply
Containment technologies:
Capping
Vertical barriers
Horizontal barriers
Extraction technologies:
Ground water Collection
Treatment technologies:
Physical treatment
Biological treatment
Chemical treatment
In situ treatment
Disposal Technologies:
On-site discharge
Off-site discharge
---
Process Options
Ground water and surface
water mo~itoring
Clay cap. multi layered cap
slurry wat I, sheet pi I ing,
grout curtains
Wei ls/pumps, subsurface
drains, and interception
trenches
Air stripping, evaporation,
carbon adsorption, ion
exchange, steam stripping,
reverse osmosis, filtration
Biological degradation
Precipitation, flocculation
oxidation, neutralization
Subsurface biorestoration,
aeration, chemical reaction
Local stream (NPOES)
Existing wastewat~r treatme
POTW, RCRA faci I ity
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not represent a risk to on-site receptors, fencing will be dismissed as a
process option.
Deed Restrictions
The use of deed restrictions is an effective method whereby specific areas of
contamination are defined on the deed to restrict usage of ground water or
construction in certain areas. This process option is retained for further
consideration.
Alternative Water Supply
Alternative water supplies may include: installation of new ground water
wells with distribution lines; providing new point of use ground water wells;
or supplying bottled water to the potential receptors of contaminated ground
water.
This option is effective for preventing the use of contaminated ground water
but it will not reduce the source of contamination. Because it was shown that
the receptors are not at risk at the present time, this option will be
dismissed dependent on the selected option limiting the migration of
contaminated ground water to the property boundaries.
Monitoring
Continued monitoring.of the ground water to detect plume migration is a viable
option to document site conditions and effectiveness of the selected remedial
action. This option alone does not reduce the source of contamination but can
reduce the potential risk of contaminated ground water consumption by alerting
NSCC that further control measures are required. This option is retained for
further evaluation.
5.2.3 Containment Actions
Containment actions minimize leaching of chemicals from the soil by providing
low permeability barriers to natural infiltration or ground water flow.
Although not a rectifying solution, containment can be used to isolate areas
of low contamination or areas where the majority of contamination has been
removed or remediated.
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Surface containment is known as capping and provides a horizontal barrier
against percolation. Subsurface barriers include a number of methods in which
cutoff walls or diversions are installed below ground to contain, or redirect,
ground water flow near a site.
Capping
Capping, or surface sealing, involves the placement of a stable (mechanically,
chemically, and long term), well-drained, impermeable cover over an area of
soil contamination to minimize leaching of contaminants to the ground water.
Capping is sometimes used when contaminated materials are left in place. A
cover is usually not employed as the sole remedial measure at a site unless
the contaminants are only in the vadose zone or a barrier against direct
contact is needed. The cap may be of a multilayer design with minimal
maintenance requi:ements, and be resistant to damage from settling and
subsidence. A gas collection system must be included when there is indication
that the underlying wastes may generate gases. Ground water monitoring wells
are typically required to detect any unexpected migration of capped wastes.
Capping offers protection against vertical leaching of contaminants to the
ground water. Primary disadvantages are the need for long-term maintenance
and uncertain design life. Maintenance costs are typically less than
excavation and treatment alternatives. Synthetic liners supported by a low
permeability base may last more than 100 years. Capping can limit the future
use of an area. Capping is retained for further evaluation.
Slurry Walls
Slurry walls are constructed in vertical trenches that are excavated under a
slurry. The slurry hydraulically shores the trench to prevent collapse while
forming a filter cake on the trench walls to minimize fluid losses into the
surrounding soils.
Design parameters for slurry walls include vertical depth and horizontal
placement.
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Considerations for the various slurry wall configurations are generally site
specific. Downgradient walls would not be effective without dewatering.
Upgradient walls require suitable site topography. Circumferential walls
offer the most extensive control of contaminant migration but are the most
expensive. Concerns regarding slurry walls include permeability, compati-
bility with the wastes, and construction difficulties.
The bedrock is fractured to a depth of greater than 90 feet. To effectively
key the slurry wall into the impermeable bedrock at the site, deep trenching
or sealing bedrock fractures ·(i.e., grouting) would be required. Because this
technology is costly and has uncertain reliability, slurry walls are dismissed
from further consideration.
Grouting
Grouting involves the injection of fluids into rock or a soil mass. The fluid
sets and forms a barrier to reduce water flow. Grouted barriers are more
costly and have higher permeabilities than slurry walls. Their main
application is for sealing rock formations. Grouting alone is rejected for
application at the site because of high costs and the uncertainties of
constructing a watertight grout in the bedrock.
Sheet Piling
· Sheet pilings are preformed steel barriers that are driven into the ground and
connected by interlocking joints. The joints are initially quite permeable
until fine .soil particles fill the void and form a seal. Grouting can be used
to seal the joints, but the procedure is costly. Rocky soils can damage or
deflect piles to the extent that the wall is no longer an effective ground
water barrier.
Sheet piling is rarely employed for other than temporary measures because of
unpredictable system permeability and cost. Their application at the site
will not be considered further.
Horizontal Bottom Sealing
Horizontal bottom sealing involves the injection or inser~ion of an inert,
impermeable, and continuous horizontal barrier in soil beneath the source of
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contamination. This type of containment strategy could be used at hazardous
waste sites in conjunction with other technologies (such as capping and slurry
walls) to ensure that the contaminants do not move into surrounding soil or
ground water. Two methods for placing grout in the subsurface are injection
grouting and jet grouting. Injection grouting pumps grout directly into the
soil. Jet grouting uses water to excavate the soils. Cuttings are air-lifted
or pumped to the surface, and air or water pressure is maintained to prevent
collapse of the cavity. The effectiveness of this technology is very
difficult to predict because it is nearly impossible to verify that voids do
not exist after injection. This technology will not be considered for further
evaluation.
5.2.4 Ground Water Recovery
The following process options have been evaluated as a means of recovering
contaminated ground water.
Extraction Wells
This technology involves the recovery of contaminated ground water from
various zones for eventual treatment and discharge. Because of the low
permeabilities associated with both the saprolite and upper bedrock zones, it
is anticipated that a number of wells with relatively small zones of influence
would be required. This technology would also help to contain any additional
contaminant migration because local ground water flow directions can be
influenced by the extraction well systems.
Because of the low values of hydraulic conductivity, the effectiveness of this
technology may be limrted. Because this is a proven t_echnology, it will be
retained for further consideration.
Subsurface Drains and Interception Trenches
Drain systems can be used to intercept and dewater areas of contaminated
ground water. In a similar manner, interception trenches can be constructed
to physically intercept shallow ground water flow without the need for
significant maintenance. This water can be collected in a common sump and
treated prior to discharge. To provide an additional barrier and extend the
zone of influence in the direction of contamination, the downgradient side of
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bedrock fractures extend to a depth of greater than 90 feet, ground water
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contaminants might migrate downward to this depth. Constructing interceptor
trenches to this depth is not a feasible technology and therefore is
considered inappropriate for application. This technology will be dismissed
from further evaluation.
5.2.5 Ground Water Treatment Technologies
Activated Carbon Adsorption
Granular activated carbon (GAC) has been used on a wide variety of waste
streams to remove chemical contaminants. Water is generally contacted with
the carbon in a series of packed bed columns. When the carbon is loaded with
chemicals, it can either be regenerated thermally or with steam, or disposed
of as a waste. Powdered activated carbon (PAC) can also be added directly to
the ground water to adsorb organics and subsequently be removed by filtration.
Carbon adsorption works best for removing low-solubility, high-molecular
weight, nonpolar compounds from water. Isotherm testing in the laboratory is
recommended to determine loading of a particular organic or combination of
organics on the carbon.
A majority of the priority pollutants detected in the NSCC ground water will
be readily adsorbed on carbon. A major exception is acetone because of its
high water solubility. However, if the water has relatively high
concentrations of other organics (nonpriority pollutants), they may load up
the carbon beds very quickly and make the use of such a system impractical.
Carbon adsorption may be a component for a ground water treatment system and
will be retained for further consideration.
Air Stripping
Air stripping is a mass transfer process in which volatile organics in water
are transferred to air. The mass transfer is controlled by the equilibrium
partitioning of the compound between water and air as represented by the
Henry's Law constant for that compound. It can be used in conjunction with
other processes, such as activated carbon or biological treatment. If
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emission of the stripped organic vapors to the atmosphere is not allowed, a
vapor phase pollution control unit may be required. This might be a fume
incinerator or vapor phase carbon adsorber.
Although several other types of air strippers are available (e.g., spray
columns and surface aerators), packed towers have the best removal
efficiencies and the most cost-effective operation.
The ground water sampled at the site contains a number of priority pollutant
volatile organic compounds that would be amenable to air stripping. This
treatment alternative will be retained for further evaluation.
Biological Degradation
Biological degradation systems remove organics from water through the
metabolic processes of microorganisms. The microorganisms utilize the
organics as an energy source converting them into carbon dioxide and more
biomass.
In conventional aerobic treatment, water to be treated flows into an aeration
tank where it is mixed with a bacterial biomass and aerated for several
hours. The biomass is then removed from the wastewater by gravity
sedimentation in a clarifier. The biomass is recycled back to the aeration
basin. A portion of the biomass is wasted by drawing off from the recycle
line.
Although many chemicals are biodegradable and others are stripped in the
aeration tanks, there are chemicals that are toxic to the biomass or resistant
to biodegradation. Metals are not biodegraded, but some are removed by
sorption onto floe particles if their concentration is not so high as to be
inhibitory. Some chemicals are only inhibitory at high concentrations. One
disadvantage of biological systems is that they work best with a consistent
quality influent. A variable concentration influent, especially one
containing toxic compounds, can adversely affect the operation of the
treatment system; consequently, good process control is required.
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Some of the chemicals in the potentially extracted ground water are
biodegradable (e.g., acetone and 4-nitrophenol). However, the ground water
could have very high levels of chlorides (>15,000 ppm) because of this high
salinity; biological treatment may pose special challenges and will have to be
supported by pilot testing. Because biotreatment destroys contaminants and is
cost-effective, it is retained for further evaluation.
Evaporation
Evap·oration is a common volume reduction technique that can concentrate
solids, salts, and other nonvolatile soluble contaminants in a wastewater.
Evaporation can be accomplished using steam in multiple-effect evaporators or
a mechanical vapor recompression (MVR) type evaporator. The latter type
offers the advantage of energy savings. The vaporized stream is condensed and
the condensate typically treated before discharge. This treatment could
include carbon adsorption or biodegradation. The bottoms from the evaporator
are in the form of a waste brine or a "salt cake" (if the evaporator is
operated as a crystallizer) and will probably require disposal in a RCRA
facility. The bottoms from the evaporator will be high in soluble salts.which
will present problems in landfilling.
Capital costs for evaporators are high compared to the other technologies
considered; operating and maintenance costs can_also be significant.
Evaporator system design must consider factors such as the buildup or' scale on
the evaporator tubes, boiling point rise of the concentrated solution, and
surging of the MVR steam compressor. Because other cost-effective options may
be feasible, evaporation will not be considered further.
Filtration
Filtration is commonly used in water treatment plants to separate solids from
a liquid stream. The stream to be filtered passes through a media that allows
the liquid to pass through while trapping the solids.
Pressure filters or rotary drum vacuums are generally used for dewatering
sludges. This allows for a reduction in sludge volume and costs associated
with transport~tion and disposal of the sludge at a landfill. Belt presses
are used for processing large quantities of sludge on a continuous basis.
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Sand filters are used to trap suspended solids in a water stream, and they
require backwashing as the filter media (e.g., sand, coal, etc.) become
clogged. Accordingly, the backwash contains a high concentration of solids
and must be treated further. Sand filters have been applied-upstream of
carbon adsorption beds to remove suspended solids that could adversely affect
the carbon working capacity. Bag and cartridge type filters that can be used
to polish the treated water effluent prior to discharge to a publicly owned
treatment works (POTW) are also available.
Because the pH adjustment process for metals removal will generate a sludge
that will have to be disposed of, filtration will be considered as a process
option. In addition, if biotreatment of the organics is used, a slimy sludge
will be generated that will have to be processed through appropriate solid-
liquid separation equipment.
In Situ Biodegradation
.In situ biodegradation enhances the naturally occurring microbial activities
found in subsurface soils. Breakdown and removal of contaminants can be
accelerated by the addition of oxyge·n, inorganic nu tr ien ts, and prepared
microbial populations. This technology has been developing rapidly and is one
of the most promising in situ treatment techniques.
General limitations of in situ biodegradation include transport of nutrients
to the distal points of contamination, the sorption and solubility of the
contaminants, toxic inhibition, and extended treatment times. Biodegradation
is more readily applied in porous sandy soils than in clayey soils where the
permeability. is low. Overdosing of nutrients can form precipitates and limit
transport by clogging the soils and bedrock fractures. The variability of pH
in the ground water will also limit the effectiveness of metabolic activity.
Soils at the site have a high percentage of clay, silt, and fine sand. This
type of soil composition is expected to have a low permeability, thereby
reducing the potential for enhanced biodegradation. In situ biodegradation is
therefore removed from further consideration.
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In Situ Chemical Treatment
In situ chemical treatment is the injection of reactive materials into the
ground water, thereby causing a chemical reaction (i.e., neutralization,
precipitation, oxidation, or reduction). In situ chemical treatment requires
that the plume be nearly homogeneous for optimum results.
Chemical treatment has been found to be effective for removing metals such as
manganese and iron by perfusing the aquifer with oxygen-rich water, thus
causing the metals to precipitate out in an oxidized state. The major limita-
tion is the potential to create additional pollution or to volatilize toxic
chemicals during this process. Given the above restrictions and the restric-
tions discussed for in situ. biodegradation, this option is dismissed from
further evaluation.
Ion Exchange/Sorptive Resins
Ion exchange is a process in which dissolved ions can be removed from a water
stream and substituted with ions from the surface of an insoluble solid
(resin) with which the solution is contacted. Most.exchange materials are
synthetic compounds that contain functional groups with exchangeable ions
attached. The exchange reaction is reversible, thereby allowing for
regeneration of the exchange material. Sorptive resins are also available
that can remove organics by a sorptive action with no exchange.
'
Ion exchange•is usually used to remove low levels of ionic species (generally
between 100 and 500 ppm) and is not cost effective at higher concentrations.
Treatment with ion exchange is typically used when very low effluent
concentrations are required and when other technologies are not applicable.
The major limitations of ion exchange are: limits on suspended sol ids, the
presence of materials that tend to form deposits in the bed, and streams that
contain organic fouling agents. In addition, the contaminants are concen-
trated in the resin regenerant, which also has to be treated. The ground
water from the "worst" NSCC monitoring wells has very high levels of TDS
(>30,000 ppm). Accordingly, ion exchange is not likely to be practical or
cost effective for this application except as a polishing technique for ground
water with lower levels of metals.
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Neutralization
Neutralization is the addition of acid or base to a wastewater for pH
adjustment. It is often performed prior to biological treatment, carbon
adsorption, ion exchange, air stripping, or oxidation/reduction process and
can be used before any treatment in which pH is critical to operation.
Neutralization of hazardous wastes can produce toxic compounds, such as the
evolution of hydrogen sulfide from the acidification of sulfide-containing
wastes.
Ground water samples collected during the RI of the site had pH values that
ranged from 3.53 to 7.87. The pH will have to be adjusted and controlled for
many of the treatment processes being considered. Therefore, neutralization
will be retained for further evaluation.
Precipitation/Flocculation
Precipitation removes metals from a wastewater by chemical addition and
adjusts its pH to a point where the metals exhibit minimum solubilities; pH
adjustment/precipitation with caustic soda, lime, or sulfides is the most
commonly used technique. The insoluble compounds precipitated can be removed
from the wastewater by flocculation, clarification, and filtration. Ferric
chloride, alum, or organic polymers are typically used for flocculation.
A suitable precipitator and flocculant is selected using bench-scale jar
tests. Mix and flocculation times, optimum pH, and sludge production can be
estimated from the jar test data. Precipitation/flocculation units function
best with a constant quality influent. A variable influent requires constant
adjustment to the chemical feed addition equipment because the chemicals must
be added in stoichiometric ratios for best performance.
If the treatment chemicals are properly handled and stored, there is little
health or environmental risk from precipitation/flocculation units. The
sludge generated as a result of precipitation may be hazardous and will have
to be disposed of properly.
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iron, and aluminum. Because these metals can be removed by pH adjustment,
precipitation will be retained for further consideration.
Reverse Osmosis
Osmosis is the movement of a solvent from a dilute solution through a semi-
permeable membrane to a more concentrated solution. In reverse osmosis (RO),
sufficient pressure is applied to the concentrated solution to overcome the
osmotic pressure and force the solvent (usually water) to the more dilute
side. This allows for a concentration of salts and contaminants on one side,
while relatively pure water is collected on the other side.
RO has been used to remove salts and inorganic compounds from brackish
water. A serious limitation of RO is the tendency of membranes to foul and
reduce the flux or product flow. The ground water extracted from the NSCC
wells will have high levels of salts and other dissolved solids. Therefore,
RO is not likely to be practical for this application and is dismissed from
further consideration.
Steam Stripping
Steam stripping is used to remove organic compounds or solvents that are
contained in wastewater at dilute concentrations. Steam stripping is
typically economical when the relative volatility of an impurity to water is
greater than 4.0.
When air emissions are not acceptable, steam stripping may allow the organics
to be removed from water and discharged as a liquid phase. However, this
method generates a concentrated organic stream that will require further
treatment before discharge.
The major priority pollutants in the NSCC ground water (i.e., 1-2
dicholorethane and 1-2 dichloropropane) are easily air stripped. The
relatively high level of chlorides will make the ground water very corrosive
so that the steam stripper will require alloy materials of construction.
Consequently, no cost or other advantage will be achieved by using steam
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stripping for this application as compared to air stripping. This technology
is dismissed from further consideration.
Existing Plant Wastewater Treatment Lagoons
The NSCC plant wastewater is currently discharged to three concrete lagoons
that are mixed by surface aerators. While the main purpose of the lagoons is
to provide back mixing and long residence time so that any variations in plant
wastewater composition are damped by the volume of the system, there is also
probably some incidental biodegradation and volatilization of organics in the
lagoons. It may be possible to mix the extracted ground water with the plant
wastewater and treat the combined streams in these lagoons. Because they are
well-aerated, the lagoons will be very effective in air stripping volatile
organics. Their efficiency as bioreactors is uncertain but they provide good
residence time and oxygen transfer. Nutrient addition may be necessary for
optimum bioactivity. Treatment in the lagoons will have little effect on
metals.
5.2.6 Off-site Treatment/Disposal
Off-site POTW
The off-site POTW will be evaluated as a possible option for the disposal of
extracted ground water. The extracted ground water would be conveyed to a
central location where it can be monitored, possibly pretreated if required,
and discharged to an existing sewer line on NSCC property. The discharged
water will have to meet existing permit conditions.
Discharges to the SaHsbury POTW would have to be handled in a manner that is
protective of human health and the environment, with full compliance to the
Clean Water Act (CWA) and RCRA. The contaminated ground water is not a listed
or characteristic hazardous waste. The Salisbury POTW has an existing .
pretreatment program for industrial users, and the discharged ground water
will have to meet the intent of that pretreatment program.
NSCC has been discharging treated wastewaters from its Cedar Springs Road
plant for over 8 years and has a sound record for discharging at or below
POTW-permitted levels. The ground water will be properly pretreated if
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required and will not pose any threat to the POTW system or its workers. The
ground water will be mixed with domestic wastewaters well before its entry
into the POTW treatment system.
The National Pollutant Discharge Elimination System (NPDES) permit for this
POTW does not need to be revised to accept this ground water; it is not
expected that the sludge generated by the POTW to be significantly altered.
The use of the POTW is deemed to be the most cost-effective and environ-
mentally acceptable manner to handle the contaminated ground water.
On-site Creek Discharge Point
The discharge of treated ground water to a natural stream or body of water
will require a NPDES permit. Dependent on permit requirements,. this option
can significantly delay the cleanup of the site and may require stricter
cleanup levels than required by the POTW.
Off-site Treatment, Storage, Disposal Facility
The off-site treatment, storage, and disposal (TSO) facility ~ill be evaluated
as a possible option for the disposal of extracted ground water. This is in
accordance with FS guidance requiring that the off-site disposal option be
evaluated.
5.2.7 Screening Evaluation Summary
A summary of the remedial technologies and associated process option evaluated
is presented in Table 5-2.
5.3 DEVELOPMENT OF REMEDIAL ACTION ALTERNATIVES
The development of remedial action alternatives is accomplished by combining
the retained technology/process option(s) from each general response action.
This section provides the rationale for formulating the remedial action
alternatives that satisfy the remedial action objectives.
5.3. 1 No Action
The no action alternative as discussed in Section 5.2. 1 is required by the NCP
to be considered during the FS. This action will remain as a standalone
alternative.
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Ground Water
General Response
Action
No action
Institutional
actions
Containment
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Remedial Technology
None
Access restrictions
•. 111111!1 ·-11111111
Table 5-2. National Starch and Chemical Corporation RI/FS Screening
Control Technologies for Ground Water Contamination
Process Option
Not appt icable
Deed restrictions
Effectiveness
Does not ensure achievement
of remedial action objectives
Effectiveness depends on con-
tinued future implementation;
does not reduce contamination
lmplementabi I ity
N/A; wi 11 I ikely require long-
term monitoring
Legal requirements
Alternative water supply New community wel I Effective in preventing use
of contaminated ground water;
no contamination reduction
Conventional dri I I ing method
requires local permit
Monitoring
Cap
Vertical barriers
Ground water
monitoring
Clay and soi I
Multi laYered cap
Slurry wal I
Grout curtain
Useful for documenting con-
ditions; does not mitigate
contamination
Effective against vertical
leaching of contaminants
into ground water; sus-
ceptible to cracking
Effective; least
susceptible to cracking
Not feasible because ground
water is contaminated within
the fractured bedrock
Not effective because of
fractured bedrock
Easily implemented; serves to
monitor contamination, not
mitigate contamination
Easily implemented; restriction
on future land use; does not
address major risks at site
Easily implemented;
restriction on future land use
Difficult to verify continuity
of slurry or backf i I I
Difficult to verify continuity
of wal I; must tie into
impervious zone
--
Cost
low O&M ( I ong-
term monitoring)
Neg I igible
-
Status
Retained
Retained
Moderate capital, Dismissed
low 0&.M
low capital,
low O&M
low capital,
low maintenance
Retained
Retained
Moderate capital, Retained
low maintenance
High capital,
low O&M
High capital,
low O&M
Oismissec
Oismisse,
-<aiit
Ground Water
Generat Response
Action
Containment
{continued)
_,_
Remedial Technology
Horizontal barriers
Collection/treat-Extraction
ment/discharge
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Subsurface drains
Physical/chemical
Treatment
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Process Option
Sheet pi le
Grout injection
Extraction wel Is/
deep we! I system
Interceptor
trenches
Neutra I i zat ion
Precipitation/
Flocculation
Ion exchange
Air stripping
Table 5-2. (Continued)
Effectiveness
Not effective because of
fractured bedrock
Not effective because of
fractured bedrock
Effectiveness can be verified
by monitoring; performance is
sensitive to design; collected
water must be treated or
disposed of
-....
lmplementabi I ity
Difficult to key to bedrock; no
excavation required; I imited to
50 feet
Continuity is difficult to
verify
Easily implemented; continued
O&M required
Effective for downgradient V~ry difficult to implement;
fracture f tow interception requires deep trenching through
rock
Effective and reliable for Readily implemented
stabi I izing pH of ground water
prior to treatment
Effective and reliable;
requires sludge disposal
Not an effective process when
dealing with saline water
conditions that exist at
site
Effective for removal of
volatile organics; not appl i-
cable to inorganics
Readily implemented
Ground water would require pre-
treatment before implementing
this option
Easily implemented; existing
aeration basins on-site may
be appl icoble
-..
Cost
High capital,
low O&M
High capital,
low O&M
Status
Dismisse,
Dismisse,
Moderate capital, Retained
moderate O&M
High capital,
low O&M
.Low capital,
moderate O&M
Dismisse,
Retained
Moderate capital, Retained
moderate O&M
High capital, Dismisse
high 0&M
Moderate capital, Retained
moderate O&M
Ground Water
General Response
Action
...
Remedial Technology
Collection/treat-Physical/chemical
ment/discharge
(continued)
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treatment
(continued)
Biological treatment
In situ treatment
I!!!!!!
Process Option
Steam stripping
Evaporation
Reverse osmosis
Filtration
Carbon adsorption
Biological
degradation
Treatment in
existing lagoons
Biodegradation
--------
Table 5-2. (Continued}
Effectiveness
Effective for removal of
volatile organics; not appl i-
cable to inorganics
lmplementabi I ity
Because of high chloride,
content equipment may require
al lay materials for construction
Effective if properly designed Would require bench-scale
testing and continued O&M
Effective in concentrating Readily implemented; membranes
the salts in wastewater; may foul if solubi I ity I imits
may be considered as a
pretreatment step
Effective in reducing sus-
pended sol ids prior to
further treatment
are exceeded
Readily implemented
Not effective for inorganic Readily implemer.ted
contaminants; not as effective
for water soluble compounds
Effective under good process
control conditions
Effective in air stripping
volatile organics may be
efficient bioreactors
Readily implemented using
conventional equipment
Readily implemented, wi I I
require testing
Cost
Moderate capital,
high O&M
High capital,
high O&M
High capital,
moderate O&M
Low capital,
moderate O&M
High capital,
high O&M
Low capita I ,
moderate O&M
Low capital,
moderate _O&M
Not effective in fractured
bedrock and saline water
conditions
Not easily implemented; requires High capital,
bench-scale testing; would
require numerous wel Is for
injection
moderate O&M
-
Status
Di smi sse,
Dismisse,
Oismisse
Retained
Retained
Retained
RetaineC1
Oismissl
Ground Water
General Response
Action
!lliilll liiiil
Remedial Technology
Collection/treat-On-site discharge
ment/discharge
(continued)
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Oft-site discharge
-..
Process Option
Chemical treatment
Local stream
RCRA facility
Sewer Line/POTW
!!!!!
Table 5-2. (Continued}
Effectiveness
Not effective i·n fractured
bedrock
Effective and reliable
Effective and reliable, but
requires transportation
Effective and reliable
iiii ----
lmplementabi I ity
Not easily implemented, would
require numerous wel Is for
injection
Not easily implemented; NPDES
permit required
Permits required
Readily implemented through
existing sewer I ine to POTW
if pretreatment standards are
met
---
Cost
High capital,
high O&M
~igh capital,
high O&M
High capital.
low O&M
Low capital.
moderate O&M
-
Status
Dismissed
Di smi ssecJ
Retained
Retained
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5.3.2 Institutional Actions
Deed restrictions and continued monitoring are two retained options that will
be combined with other technologies to provide additional protection and to
verify effectiveness of a particular alternative.
5.3.3 Containment
The only retained option for the general response action of containment is
capping. Based on the results of Section 4.0, ground water is the only
potential exposure pathway at the site. The surface soils are not an
environmental or public health concern. Capping is not a feasible alternative
for a ground water contamination problem. Capping may be effective for
slowing the migration of the remaining leachate in the vadose zone under the
trench area, but this will only extend the duration of a remedial action to
remove the source or .contamination. Also it is favorable to leave the area
uncapped to promote percolation of precipitation so that any remaining
contaminants can be removed from the soil by the natural flushing action into
the ground water whereby they can be retrieved by ground water extraction.
Therefore, capping is dismissed as a viable option as a stand-alone
alternative or in combination with other techniques.
5.3.4 Collection Treatment/Discharge
5.3.4. 1 Extraction
The most feasible option available for extracting the ground water is by wells
equipped with submersible pumps. The pumping rate, well placement and number
of wells required to effectively remediate the contaminant plume is dependent
on the site and waste characteristics. The pumping rate will be restricted to
the maximum flow allowed by the POTW. Given the size of the identified
contaminant plume from the RI report, four extraction wells were estimated to
be adequate to retard the migration of the plume so that contaminated ground
water can be removed. The placement of the wells at the periphery of the
plume will ensure that contamination will not migrate off site, and the low
concentration of contaminants at this location may be effectively treated by
the POTW.
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Another extraction option is to place the wells directly into the identified
plume near the trench area where the concentration of contaminants is high
thereby capturing the source of contamination. During the Remedial Design,
further. evaluation of the various pumping scenarios will be performed by
actual field tests and using the ground water model discussed in Section 3.0.
5.3.4.2 Ground Water Treatment Processes
As discussed in the previous section, the overall plume containment strategy
will determine the level of contamination in the extracted ground water. If
the recovery wells are located near the trench area, the ground water will be
highly contaminated with both metals and organics and extensive treatment will
be required. If wells on the periphery of the plume are employed,
contamination will be lower and effluent criteria will be easier to attain.
If the wells are placed directly in the trench area, it is unlikely that any
of the technologies described in Section 5.2 will provide adequate "stand
alone" treatment. Treatment processes combining various technologies will be
required. Screening these processes included an evaluation of their ability
to reach the treatment goals for the ground water, their potential adverse
environmental effects, the development work needed to demonstrate their
acceptability, and their cost. Several of the most promising treatment
processes are discussed in the following paragraphs ..
Me.tals Removal Processes
Two metals removal techniques (precipitation and ion exchange) have been
considered. Initial laboratory tests of water collected from monitoring wells
within the trench area indicate that water treated by precipitation can
probably meet the anticipated discharge criteria for metals. Ion exchange can
typically produce treated water of equivalent quality, but it also produces a
regenerant solution in which the metals removed from the water are
concentrated. This regenerant must be treated (typically by precipitation) to
produce a metals sludge for disposal. If the trench area ground water
contains high levels of metals, ion exchange is not a cost-effective
concentration technique and precipitation is the preferred process. Ion
exchange could be considered if extraction wells on the periphery of the plume
are employed and metals concentrations are low.
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Although precipitation by pH adjustment to minimum metals solubility is the
primary removal mechanism, other technologies are involved as described in
Section 5.2. Coagulation/flocculation will be employed to increase the size
of the precipitated metal oxides and hydroxide particles. This will decrease
the size of the clarification equipment and improve effluent quality. The
settled sludge from clarification will contain too much water and must be
filtered for disposal in a landfill as solid waste. The proposed metals
removal process therefore contains pH adjustment for precipitation,
flocculation, and clarification with filtration of the metals sludge.
Organics Removal Processes
Ground water at NSCC could contain 1,2-dichloroethane (DCA), 1,2-dichloro-
propane (DCP), Bis(chloroethyl) ether (BCE), 4-nitrophenol, and acetone.
These compounds are priority pollutants and/or HSL organics that are of
-specific regulatory concern. The water·is also expected to contain
unidentified nonhazardous organics that will result in its having significant
chemical_oxygen demand (COD), and biological oxygen demand (BOD). Three
processes were considered for organic removal, biotreatment, air stripping
followed by biotreatment, and air stripping followed by treatment in carbon
columns. All options are based on discharge to the POTW. Biotreatment can be
accomplished in either the existing lagoons or in a new facility.
Although the salinity of the trench area ground water is fairly high, bio-
treatment in an aerated system (such as the existing lagoons) by an acclima-
tized culture could probably degrade the acetone, BCE, and nitrophenol.
Unfortunately, the DCA and DCP will be stripped into the air before they are·
degraded. Depending on the concentrations of these· two compounds in the
ground water, these air emissions could result in noncompliance with the
proposed North Carolina toxic air pollutants· regulations. This option can be
considered if concentrations of DCA and DCP are low but not low enough to meet
pretreatment standards as in the plume periphery extraction scheme.
Air stripping followed by biotreatment is the second alternative treatment
process. The DCA and DCP can be air stripped from the ground water in a
packed column and if necessary destroyed by incineration of the contaminated
air from the stripper (flue incineration). The remaining HSL organics and
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priority pollutants can probably be degraded in an biological treatment
system. This option can be designed to meet air quality requirements and also
lower the COD and BOD of the ground water. This process would be required if
highly contaminated water from the trench area is treated. The biotreatment
system can be either the existing lagoons or a new facility.
Carbon treatment of ground water was also considered. Again, the DCA and DCP
can be air stripped from the ground water and destroyed by incineration if
required. The ground water is then treated in carbon columns to remove the
remaining priority pollutants and HSL organics. Because the ground water is
expected to contain unidentified organics in addition to the HSL organics and
priority pollutants, it is not possible at this time to predict the amount of
carbon consumed by this process. This process is also not a cost-effective
way to reduce the COD and BOD of the ground water. If the COD and BOD of the
ground water are low enough that discharge directly to the POTW is not
acceptable, this process could be considered.
5.3.4.3 Discharge of Ground Water
Three options for discharge of ground water were considered. They include
discharging untreated ground water to an off-site RCRA TSO facility, discharge
into a small on-site stream, and discharge to the Salisbury POTW.
The ground water can be disposed of at a RCRA permitted facility. This would
require installation of truck loading racks and ground water surge tanks. The
transportation of this waste would entail some public risk. This would be an
expensive alternative but it will be considered as a CERCLA requirement.
The NSCC property borders Grants Creek and contains unnamed tributaries for
this small creek. Discharge into these streams would require an NPDES permit
that could require several months to obtain. Because the permit would set
very stringent discharge limits for the contaminants in the ground water,.
extensive treatment would be required and the NPDES standards may not be
achieved. If highly contaminated water from the trench area is extracted, its
salinity will preclude its discharge into these streams. Because of these
problems this alternative will not be considered further.
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Discharge to the Salisbury POTW is a promising alternative that was discussed
in Section 5.2.6. In summary, effluent criteria will be negotiated with the
Salisbury POTW so that the NSCC discharge will meet the City of Salisbury
guidelines and will not adversely affect the POTW treatment system, sludge
disposal, or NPDES permit.
5.3.5 Development of Site-Wide Alternatives
Site-wide alternatives are developed by combining the retained technologies
from each of the general response actions discussed above.
Alternative 1 -No Action
This alternative is required by the fS guidance to serve as a base alternative
for comparison purposes. The institutional action is included in the no
action alternative so the effectiveness of no action can be verified by
continued monitoring to ensure ARARs are not exceeded at the property line.
Alternative 2 -Off-Site Disposal
This alternative is also required by the fS guidance. This alternative
includes extracting the ground water and transporting it to an off-site TSD
facility for disposal. In addition continued ground water monitoring will be
part of this alternative to verify the effectiveness of the extraction
process.
Alternative 3 -Ground Water Extraction and Discharge to POTW
Considering the pumping option of placing the wells at the periphery of the
ground water plume, the direct discharge of the collected water to the POTW is
considered a feasible alternative for evaluation. Ground water monitoring
will also be a part of this alternative for the same reason given for
Alternative 2.
Alternative 4 -Ground Water Extraction and Treatment
This alternative is formulated by considering the extraction option of placing
the wells directly in the trench area where contaminant concentrations are at
their highest levels, thereby requiring pretreatment before the extracted
ground water can be discharged to the POTW. Continued ground water monitoring
is required for the same reason given for Alternative 2.
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Alternative 5 -Ground Water Extraction and Treatment in Existing Lagoon
System
This alternative is a result of considering the same extraction option given
for Alternative 3 combined with transferring the ground water to the existing
on site treatment system. This alternative also includes ground water
monitoring.
Further discussion and evaluation of these alternatives is provided in Section
6.0.
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6.0 DETAILED ANALYSES OF REMEDIAL ACTION ALTERNATIVES
This section provides a separate detailed analyses for each alternative
defined in Section 5.3. The detailed analyses will include a technical
evaluation, institutional evaluation, public health evaluation, environmental
impacts evaluation, and a cost evaluation as defined in the approved RI/FS
work plan dated December 1986.
6. 1 ALTERNATIVE 1 -NO-ACTION
The no-action alternative includes no remedial action measures, but will
include continued ground water and surface water monitoring and the filing of
a deed restriction identifying the areas of contamination as defined by the RI
report.
The deed restriction will prevent on-site development in the trench areas and
also on-site use of the ground water. The surface water and ground water
monitoring will be used to verify that the ARARs are not exceeded at the
property line. As discussed in Section 2.0, Grants Creek and unnamed
tributaries form aquifer discontinuities near NSCC property lines that further
reduce the potential for ground water contaminants to reach the property
line.
The no-action alternative is easily implemented by installing three additional
monitoring wells near the site boundary and collecting samples on an annual
basis for up to 30 years. In addition to the ground water monitoring, surface
water samples will be collected from Grants Creek and the unnamed tributaries
that drain the site. The surface water samples will be collected at the same
time that ground water samples are collected. The collected ground water and
surface water samples will be analyzed for the following indicator parameters:
volatile organics, HSL metals, specific conductance, pH, chloride, and total
organic carbon (TOC) using the same method of analysis as performed for the
RI. The deed restrictions are easily implemented by processing the
restrictions through a local attor~ey and the Rowan County or City of
Salisbury Register of Deeds.
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The trench disposal areas as defined in the RI report do not present a health
risk through the direct contact of surface soils as discussed in Section
4.0. Therefore, access restriction to this area is not required.
Contamination (over time) will be reduced because of biodegradation, chemical
transformation, soil attenuation of contaminants, and dilution. The rate of
these phenomena is uncertain, and the no-action alternative serves to monitor
the movement of the contaminant plume to determine if these phenomena can
prevent ground water ARARs from being exceeded at the property line.
Technical Evaluation
The no-action alternative does not provide additional mitigation to the ground
water contamination beyond the natural processes that are currently taking
place. This alternative monitors the surface water and ground water to verify
that ARARS at the property line are not exceeded before any future remedial
actions can be taken. This alternative is considered a long-term monitoring
strategy.
Institutional Evaluation
It is possible that in the long term the no-action alternative may not
preserve the ARARs at the property line for ground water as defined in Section
4.0.
Public-Health Evaluation
The public health evaluation for no remedial action is presented in Section
4.0. Surface water features to the northwest, west, and southwest reduce the
likelihood that contaminants could migrate via ground water off site. Public
' health will not be at risk unless the ground water contaminant plume migrates
past the property line at levels in excess of ARARs. Chemical concentrations
are likely to be reduced as the plume moves toward the property line due to
the natural processes of biodegradation, chemical transformation, soil
adsorption, and dilution.
Environmental Impact Evaluation
The impact on the environment by implementing the no-action alternative is
discussed in Section 4.0.
CEE13636
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Cost Evaluation
The capital costs associated with the no-action alternative are the attorney
fees for processing the deed restrictions and the installation of the new
monitoring wells. Operations and maintenance costs include ground water and
surface water sampling from four monitoring wells and laboratory analysis for I 30 years.
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Capital Costs
Deed restriction lawyer fees
Installation of three ground water
monitoring wells
Operation and Maintenance Costs
Subtotal
Collecting ground water and surface water
samples and performing labor.atory analysis
Present Worth
Assumptions:
Ground water sampling and analysis is
performed for 30 years.
The discount rate is 10% for the period of
performance.
p = F + A (PIA, 10%, 30)
p = Present Worth
F = Capital Costs
A = Annual Cos ts
p = 11,000 + 11,500 (9,427) = $119,000.
6.2 ALTERNATIVE 2 -OFF-SITE DISPOSAL
$ 1 ,ODO
10,000
$11 ,ODO
$11, 500/yr
This alternative includes the extraction of contaminated ground water, the
collection of ground water at a central on-site location, and the off-site
disposal of the collected ground water by bulk tank trucks to a RCRA TSD
facility.
CEE13636 6-3 -,,. ,,..,... ,,..,,..
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An extraction rate of 50,000 gallons per day was used to simulate extraction
rates for ground water remediation.
4-inch diameter wells at a depth of
This requires the installation of four
approximately 100 feet. These wells will
be placed near the identified trench area spaced approximately 250 feet apart.
The extracted ground water will be placed in an aboveground tank that will
store contaminated ground water for no more than 90 days. The tanks will
store the extracted ground water until it is transferred to bulk tank trucks
and transported to a RCRA TSD facility.
Continued ground water monitoring will be performed after removal of the
contaminated ground water to verify effectiveness of ground water extraction
operation.
Technical Evaluation
Disposal of ground water at an off-site RCRA facility will provide a reduction
of risk to public health and the environment immediate surrounding the NSCC
site by removal of the source of contamination. But the off site transport of
contaminated ground water will increase the probability of exposure to the
general public by potential vehicle accidents and spills while transferring
water.
This alternative is readily implemented. Because this alternative is designed
to extract ground water near the trench area, the source of contamination in
the ground water will be substantially reduced.
Institutional Evaluation
All ARARs will be met by this alternative. No permits are needed to implement
this alternative.
Public Health Evaluation
Risks to human health and the environment near the site from ground water
contamination is permanently eliminated. However, the public will be exposed
to additional risks that result from transporting contaminated ground water to
the TSD facility. These risks include the direct impact of motor vehicle
accidents and the additional environmental burden associated with diesel
CEE13636
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engine emissions. Additional monitoring wells will be installed to verify
that ground water remediation was successful.
Environmental Impact Evaluation
The environment will be protected by removing subsurface contamination and
ensuring that ground water contaminants do not migrate further in the aquifer.
Cost Evaluation
The capital costs associated with this alternative are the installation of
extraction wells with pumps, construction of an aboveground tank, and the
installation of three ground water monitoring wells. The operation and
maintenance costs will be the transportation and disposal of bulk liquid waste
to a RCRA TSD facility. The operation of the ground water extraction system
is estimated to require 10 years to completely remove the contaminated
plume. Ground water monitoring will be continued for 30 years. The present
worth cost for this alternative is calculated below.
Capital Costs
Installation of four deep extraction wells
with pumps and piping
Installation of three monitoring wells
Construction of a 350,000-gallon tank
Subtotal
$
$
91,000
10,000
67 000
168,000
I Operation and Maintenance Costs
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Transporting bulk liquids
Disposal of 18 million gallons/yr
Operating and maintaining pumps and equipment
Collecting ground water samples and
performing laboratory analysis
Present Worth
Subtotal
$ 1,463,000/yr
15,221,000/yr
102,000/yr
$16,786,000/yr
8,000/yr
P = 168,000 + 16,786,000 (PIA, 10% 10 yr)+ 8,000 (PIA, 10%, 30 yr)
P = 168,000 + 16,786,000 (6. 144) + 8,000 (9.427)
P = $103,377,000.
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6.3 ALTERNATIVE 3 -GROUND WATER EXTRACTION AND DISCHARGE TO POTW
This alternative involves installing four extraction wells to remove
contaminated ground water and discharging the ground water to the Salisbury
POTW for treatment. NSCC currently discharges plant wastewater effluent to a
sewer line that runs across NSCC property. The extracted ground water will be
discharged into the existing sewer line. Extraction wells would be strate-
gically located near the periphery of the plume in order to provide optimum
plume containment while generating flow rates and contaminant concentrations
that would not affect POTW operation.
Three monitoring wells would be installed to the northwest, west, and
southwest to verify that ground water contamination was being properly
remediated.
The POTW is a 5 million gallon per day biological treatment plant. Some
bench-scale testing may be required by the POTW to verify that the POTW is
capable of treating this contaminated ground water. The site ground water
model would be used to strategically locate the ground water extraction wells.
Technical Evaluation
The contaminated ground water contains some contaminants that will require
POTW plant impact evaluation. The actual concentrations of organics and
metals would have to be negotiated with the Salisbury POTW. Extraction wells
can be located to control the ground water contaminant plume while meeting
POTW negotiated discharge levels and remediating subsurface contamination.
Bench-scale testing may be required to satisfy the POTW that the plant
operation will not be impacted. Extraction flow and discharge rates will be
determined by performing pump tests at several existing monitoring wells.
Institutional Evaluation
The discharge to the Salisbury POTW will have to be negotiated with the City
of Salisbury. The city is currently modifying the pretreatment standards for
industrial users and its impact on any proposed discharge will be determined
as these standards are finalized.
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Public Health Evaluation
This alternative will be designed so that ground water is extracted at a rate
to control contaminant plume movement and safeguard ARARs at the NSCC property
line. Consequently, the public health will be safeguarded by preventing
consumption of any contaminated ground water.
POTW employees will be protected by controlling the release of contaminants
into the POTW at levels that protect POTW employees. These levels are
dependent on negotiated flow rates, effluent criteria, and extraction we11·
placement. These concerns will be finalized as a part of any remedial action
design.
Environmental Impact Evaluation
The extraction system will control any ground water plume movement so that
contaminants will not move off site or into surrounding surface water
features.
Cost Evaluation
Capital costs include installation of four extraction wells (along with
associated piping and pumps) and three additional ground water monitoring
wells. Operation and maintenance costs for extraction system operation (10
years) and monitoring (30 years) are also inc1uded. Costs to POTW are also
included.
Capital Costs
Installation of three additional ground
water monitoring wells
Installation of four deep extraction wells
Subtotal
Operation and Maintenance Costs
Operating and maintaining extraction system
POTW surcharges
Collect ground water samples and perform
laboratory analysis
CEE13636
06/28/88 F5
6-7
$ 10,000
91,000
$101 , 000
$ 10,000
25,000
8,000
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Present Worth
P = 101,000 + 35,000 (PIA, 101, 10 yr) + 8,000 (PIA, 10%, 30 yr)
P = 101,000 + 35,000 (6. 144) + 8,000 (9.427)
P:$391,000.
6.4 ALTERNATIVE 4 -GROUND WATER EXTRACTION AND TREATMENT
In this alternative all extraction wells are immediately downgradient from the
trench area where most of the contaminants are located. The ground water will
initially be highly contaminated and require extensive treatment before dis-
charge to the Salisbury POTW. The pretreatment system will be designed when
acceptable effluent limits are negotiated with the POTW and the concentration
of contaminants in the extracted ground water has been predicted by the
model. This alternative gives the most rapid removal of the highly contami-
nated trench area ground water and the lowest total volume of extracted ground
water, but results in discharge of high levels of salts to the Salisbury POTW.
The most promising treatment process includes pH adjustment, precipitation,
flocculation, and cl.ar ification for metals removal; air stripping with fume
incineration followed by biotreatment is required for removal of HSL organics,
and reduction of COD and BOD. This process would be designed to meet all
pretreatment requirements for producing a final effluent suitable for
discharge to the Salisbury POTW and to meet air quality criteria. Although.
this process employs technologies that have been used successfully on similar
wastes and therefore has a high probability of success, it has not been
demonstrated on the NSCC ground water and will require substantial small-scale
or pilot testing before a final design for construction can be developed.
Precipitation by pH adjustment with lime is the primary metals removal mechan-
ism in this process. The metals will be removed as insoluble oxide and
hydroxide solids. The optimum pH for metals removal will be determined
through bench-scale testing and operating experience. The metals sludge
formed in the lime precipitation will be removed by flocculation and
clarification. The clarifier is a lamella unit in which the water flows over
a number of parallel plates. The solids settle out onto and down the plates
to a sludge compartment. The clarified water overflows to the air stripper.
Effluent quality will be determined by bench-scale testing. The sludge from
the clarifier will be thickened by gravity settling before it is filtered in a
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pressure plate filter. The filtrate from the press will go to the air
stripper feed tank. The filter will produce a cake that contains 30 to 50
percent solids and will probably be suitable for disposal in a landfill. The
performance of the filter needs to be determined by filter leaf tests. This
filter cake will probably contain enough leachable metals to require disposal
as a RCRA waste. If this is the case, a sludge drying step may be cost
effective. This will be determined when the filter leaf tests are run.
The vinyl chloride, 1,2-dichloroethane, and 1,2-dichloropropane will be
removed from the ground water in the air stripper. The contaminated air from
the top of the stripper will contain too much 1,2-dichloroethane for direct
discharge to the atmosphere and will need to be treated in the fume
incinerator. The incinerator is a gas-fired unit designed for 99.9 percent
destruction of the organics in the inlet air. This is accomplished by
combustion at 1600°F. The chlorinated org.anics are combusted to carbon
dioxide, water, and hydrogen chloride gas which are discharged to the
atmosphere.
The ground water is pumped from the air stripper to the oxidation lagoon for
biological degradation of the remaining priority pollutants, HSL organics, and
for reduction of COD and BOD. Biotreatment has been effective on wastes
similar to this ground water but must be demonstrated. One concern is that
the salinity of the wat~r is high compared to what is seen in most
biotreatment systems. This problem could be addressed by developing a culture
that is acclimatized to the NSCC ground water. This culture could be
generated in laboratory-and pilot-scale work and could be used to seed the
full size system. The other concern is that the concentration and identifica-
tion of all the organics in the ground water are not known, which makes it
difficult to guarantee the effectiveness of the biotreatment system in
reducing the' COD and BOD of the waste. These are significant concerns, and
they will be addressed in the remedial action design phase.
Technical Evaluation
Successful implementation of this alternative depends on a more extensive
development program than the other alternatives. Ground water collection and
treatment would be delayed by 12 to 18 months for pilot testing, design, and
construction. During this time, further degradation in ground water quality
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may occur. Ground water monitoring is required to verify performance of
extraction.
Institutional Evaluation
All ARARs will be met by this alternative. A permit will be obtained for
discharge to the POTW.
Public Health Evaluation
Risks to human health and the environment from ground water contamination is
significantly reduced by ground water extraction and treatment.
Environmental Impact Evaluation
This alternative has the same impact as Alternative 3 except that the
discharge of salts to the POTW will initially be much higher. The impact of
this on the NPDES permit for the Salisbury POTW and on the water quality in
the Yadkin River must be evaluated.
Cost Evaluation
The capital costs associated with this alternative are the installation of
extraction wells with pumps, design, and installation of the ground water
treatment system. The cost estimate for the treatment system will be further
refined by results of the treatability and pilot testing that will be I necessary before the proposed process can be implemented. The operation and
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maintenance costs are the annual ground water sampling and analysis for 30
years and the operation and maintenance of the treatment system for 10
years. The capital costs, O&M costs, and present worth costs are presented
below.
Capital Costs
Installation of three ground water
monitoring wells
Installation of four deep extraction
wells with pumps and piping
Treatability testing
Final system design (at 15 percent)
Project management (at 15 percent)
Installation and construction of
treatment system
Subtotal
CEE13636 6-10
$ 10,000
91,000
200,000
250,000
250,000
1,754,000
$2,555,000
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Operation and Maintenance Costs
Operating and maintaining treatment
system*
POTW surcharges
Collecting ground water samples
and performing laboratory analysis
Present Worth
$ 623,000lyr
50,000lyr
8,000lyr
P = 2,555,000 (PIA, 10%, 10 yr)+ 8,000 (PIA, 10%, 30 yr)
P = 2,555,000 + 673,000 (6. 144) + 8,000 (9.427)
P = 6,765,000.
*Includes maintenance, labor, utilities, and sludge disposal.
6.5 ALTERNATIVE 5 -GROUND WATER EXTRACTION AND TREATMENT IN EXISTING LAGOON
SYSTEM
This alternative involves the extraction of ground water as described in
Alternative 3 combined with pretreatment as required to allow the ground water
to be.combined with the· current plant effluent and treated in the existing
lagoons for discharge to the Salisbury POTW. The level of pretreatment
required will depend on the quality of the ground water and the effluent
limits set by the POTW, neither of which has been defined at this time. As
with Alternative 3, the extraction wells will be located for optimum waste
loads and concentrations.
The pretreatment system will be designed when acceptable effluent limits are
negotiated with the POTW and the concentration of contaminants in the
extracted ground water has been predicted by the model. The pretreatment
system may include metals removal by lime precipitation, stripping of volatile
organics, or treatment with activated carbon. The various pretreatment
processes are described in Sections 5.3. 1 and 6.4. As discussed in Section
6.4, treatability studies are required to demonstrate the success of any
pretreatment processes on NSCC ground water.
CEE13636 6-11
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Depending on the location of the extraction wells, the ground water may
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contain heavy metals, priority pollutants, and HSL organics as well as
unidentified organics. The extraction and pretreatment scheme will be
designed to control the ground water contaminant plume, remediate subsurface
contamination, and meet all requirements of the POTW. Treatability studies
will be required to demonstrate the pretreatment processes, and NSCC will also
have to confirm that mixing with the pretreated ground water will not affect
the discharge of the current plant effluent.
Institution Evaluation
The discharge to the Salisbury POTW will have to be negotiated with the City
of Salisbury. The city is currently modifying their pretreatment standards
for industrial waste. The NSCC system will be designed to meet these
standards when they are finalized.
Public Health Evaluation
This alternative assumes that ground water is extracted at a rate to control
contaminant plume movement and safeguard ARARs at the NSCC property line.
Consequently, the public health will be safeguarded by preventing consumption
of any contaminated ground water.
POTW employees will be protected by controlling the release of contaminants
into the POTW at levels that protect POTW employees. These levels are
dependent on negotiated flow rates, effluent criteria, and extraction well
placement. These concerns will be finalized as a part of any remedial action
design.
Environmental Impact Evaluation
The extraction system will control the ground water plume movement so that
contaminants will not move off site or into surrounding surface water
features.
Cost Evaluation
The capital costs associated with this alternative are the installation of
extraction wells with pumps, design, and installation of any ground water
pretreatment system that might be required to make the ground water suitable
CEE13636 6-12
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for discharge to the existing lagoon system. Capital cost estimates have been
developed for three possible pretreatment scenarios. The first assumes that
no pretreatment is needed. The second assumes some of the ground water must
be treated by metals removal, while the third assumes that both metals removal
and air stripping are necessary. The cost estimates for any pretreatment
system will be further refined by results of the treatability and pilot
testing that will be necessary before this alternative can be implemented.
The operation and maintenance costs are the annual ground water sampling and
analysis for 30 years and the operation and maintenance of the treatment
system for .10 years. The capital costs, 0&M costs, and present worth costs
are presented on the following page.
CEE13636 6-13
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Capital Costs
Installation of three ground water
monitoring wells
Installation of four deep extraction
wells with pumps and piping
Treatability studies
$
Case Ia
10,000 $
91,000
40,000
-0-
-0-
Case nb Case IIIc
10,000 $ 10,000
91,000 91,000
69,000 104,000
69,000 104,000
69,000 104,000 Process design (at 15 percent)
Project management (at 15 percent)
Installation and construction of -0-460,000 710 000
treatment system
Subtotal $141,000 $768,000 $1 , 123,000
Operation and Maintenance Costs
Operatin8 and maintaining treatment $ 60,000 $240,000 $ 298,000
system
POTW surcharges 25,000 50,000
Collecting ground water samples 8,000 8,000
and performing laboratory analysis
Case I Present Worth
P = 141,000 + 85,000 (PIA, 10%, 10 yr)+ 8,000 (PIA, 10%, 30 yr)
P = 141,000 + 85,000 (6.144) + 8,000 (9.427)
P = 739,000.
Case II Present Worth
P = 768,000 + 290,000 (PIA, 10%, 10 yr)+ 8,000 (PIA, 10%, 30 yr)
P = 768,000 + 290,000 (6. 144) + 8,000 (9.427)
P = 2,625,000.
Case III Present Worth
50,000
8,000
P = 1,123,000 + 348,000 (PIA, 10%, 10 yr) + 8,000 (PIA, 10%, 30 yr)
P = 1,123,000 + 348,000 (6. 144) + 8,000 (9.427)
P = 3,337,000.
acase I =groundwater can be treated in existing lagoons without
pretreatment.
bcase II= pretreatment for metals removal.
cease III = pretreatment by metals removal and stripping of volatile
organics.
dincludes labor, maintenance, utilities, and sludge disposal.
CEE13636 6-14
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7.0 COMPARATIVE ANALYSIS OF ALTERNATIVES AND
RECOMMENDATIONS OF SELECTED ALTERNATIVE
This section provides a comparative analysis of the alternatives presented in
Section 6.0 along with a recommendation of the selected alternative. The
purpose.of the analysis is to identify the advantages and disadvantages of
each alternative relative to one another so that the most feasible, cost-
effective alternative can be identified which is protective of human health
and the environment. The alternatives will be analyzed using the same
criteria that each was analyzed independently for in Section 6.0 (i.e.,
technical evaluation, institutional evaluation, public health evaluation,
environmental impact evaluation, and cost evaluation). The independent
analysis of each alternative is summarized in Table 7-1.
7. 1 COMPARATIVE ANALYSIS
Technical Evaluation
Alternative 1 is not as effective in reducing the potential risk from the off-
site migration of contaminated ground water as the other alternatives.
Alternatives 2, 3, 4, and 5 provide for the removal of contaminated ground
water by extraction wells. Alternatives 3 and 5 will have less of an impact
on the POTW than Alternative 4 because of the lower saline concentrations in
the extracted ground water from the plume periphery. Alternatives 2 through 5
are reliable, but Alternatives 2, 4, and 5 require a higher degree of
operation and maintenance to be effectively reliable. All alternatives are
dependent on continued ground water monitoring to verify their reliability.
Alternatives 1, 2, and 3 are readily implemented, while Alternatives 4 and 5
require more time (12 to 18 months) to test the treatment and to design and
construct the system.
Institutional Evaluation
All alternatives in the short term will meet the ARARs given in Section 4.0 at
the property lines. Alternative 1 in the long term may exceed ARARs at the
property line. Alternatives 3, 4, and 5 will require negotiation with the
POTW.
CEE13637
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Evaluation
Criteria
TECHNICAL
Short-term
effectiveness
Long-term
effectiveness
Reliability
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Table 7-1. Summary of Alternative Analyses for National Starch Chemical Corporation
Alternative
No-
Action
Reduction of risk
to ingestion in
the short-term of
implementation of
deed restriction
Long-term risks
remain signif-
icant for pos-
sible off-site
migration of
contaminated
ground water
Reliance on
enforcement of
institutional
control; high
level of
residual risks;
further degrad-
ation of ground
water possible
Alternatives
Alternative 2
Off-Site
Disposal
Alternative 3
Ground Water Extract/
Discharge to POTW
Ground water
extraction may
take up to 10
years for ARARs
not to be exceeded
at site boundary
Risks would be
eliminated after
an estimated 10
years of pumping
Same as Alternative
2
Risk would be elim-
inated the same as
Alternative 2
Remedy will be Remedy will be
highly reliable ·highly reliable
because of removal with continued
of contaminated O&M
ground water
Alternative 4
Ground Water Extract/
New On Site
Treatment System
Ground water extrac-
tion and treatment
system would take up
to 12 to 18 months for
pilot testing, design,
and construction
Risk would be
eliminated the same
as Alternative 2
Remedy will be highly
reliable with con-
tinued O&M
Alternative 5
Ground Water
Ex tract/Treat
in Existing
Lagoon System
Same as Alter-
native 4
Risk would be
eliminated
the same as
Alternative 2
Same as
Alternative 4
Evaluation
Criteria
Implementability
INSTITUTIONAL
CEE13637 A
06/28/88 F4
Alternative
No-
Action
Continued ground
water monitoring
will track plume
movement but will
not remediate
contamination
Continued ground
water monitoring,
easy to implement
and cons true t;
spread of ground
water contam-
ination will
make remediation
more difficult
in the future
Possible that
ARARs may be
exceeded at
property line
Table 7-1. (Continued)
Alternatives
Alternative 2
Off-Site
Disposal
Alternative 3
Ground Water Extract/
Discharge to POTW
Ground water
monitoring will
verify effective-
ness of the
extraction system
Readily imple-
mented; monitoring
needed to assess
effectiveness of
ground water
extraction
Ground water
monitoring will
verify effective-
ness of the
extraction system
Same as
Alternative 2
All ARARs will be All ARARs will be
met at property met at property
line line
Alternative 4
Ground Water Extract/
New On Site
Treatment System
Ground water
monitoring will
verify effective-
ness of the
extraction system
Treatment facility
requires special
equipment and
operators; pilot
testing is required
to verify treatment
effectiveness
All ARARs will be
met at property
line
Alternative 5
Ground Water
Extract/Treat
in Existing
Lagoon System
Ground water
monitoring will
verify effec-
tiveness of the
extraction
system
Same as
Alternative 4
All ARARs will
be met at
property line
~
Evaluation
Criteria
PUBLIC HEALTH
ENVIRONMENTAL IMPACT
COST
Alternative
No-
Action
Minimal reduction
in toxicity, mobil-
ity, or volume of
contaminated
ground water;
therefore, risks
remain for
possible future
degradation of
ground water
public in ground
water transpor-
tation
No significant
environmental
impact from con-
struction; envi-
ronmental degrad-
ation will
continue as ground
water contamina-
tion spreads
119,000
--
Table 7-1. (Continued)'
Alternatives
Alternative 2
Off-Site
Disposal
Alternative 3
Ground Water Extract/
Discharge to POTW
Toxicity and volume
of ground water
contamination
completely
eliminated; there-
fore, risk to
human health is
permanently
eliminated;
increase risks to
Aquifer drawdown
during ground water
extraction; risks
to environment
from contaminated
ground water
permanently elim-
inated
103,377,000
Toxicity and volume
of ground water
contamination
completely elimi-
nated; therefore,
risk to human
health is per-
manently eliminated
Same as Alternative
2
391,000
*The range of costs are discussed in Section 6.5.
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Alternative 4
Ground Water Extract/
New On Site
Treatment System
Same as Alternative
3 plus protection
required for air
emissions
Same as Alternative
2
6,765,000
--
Alternative 5
Ground Water
Extract/Treat
in Existing
Lagoon System
Same as Alter-
native 4
Same as alter-
native 2
739,000 -
3,337,000*
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Public Health and Environmental Evaluation
Alternatives 2, 3, 4, and 5 are the most effective in reducing the potential
risks to the public health and the environment. Alternative 1 will not reduce
the potential risks to either the public health or the environment.
Cost Evaluation
The least expensive alternative is Alternative 1, but this may not provide
protection to the public health or environment in the long term. Alternative
2 is the highest in cost compared to all the rest of the alternatives and its
cost is prohibitive.
Alternatives 2, 4, and 5 have high operation and maintenance costs compared to
Alternatives 1 and 3. Alternative 3 is the most cost-effective remedial
action that provides the same degree of protection to the public health and
environment as Alternatives 2, 4, and 5.
7.2 RECOMMENDED ALTERNATIVE
Based on the above evaluations, Alternative 3 is determined to be the most
technically feasible, cost-effective remedial action that provides protection
to the public health and environment. No additional level of protection is
afforded the public health or environment by spending additional money for
Alternatives 4 or 5.
The selection of Alternative 3 is dependent upon successful negotiations with
the Salisbury POTW for discharge of extracted ground water. Pending the
finalization of these negotiations and any bench-scale_testing, the
implementation of this remedial alternative may begin.
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REFERENCES
Grant, Eugene L., W. Grant Ireson, and Richard S. Leavenworth, Principles of
Engineering Economy, John Wiley & Sons, February 1976.
Paustenbach, Dennis, J., 1987, "Assessing the Potential Environment and Human
Health Risks of Contaminated Soil", Comments on Toxicology, Vol. 1:185-220.
U.S. Environmental Protection Agency, 1985, Guidance on Feasibility Studies
under CERCLA (Comprehensive Environmental Response, Compensation and Liability
Act), USEPA, Washington, D.C., EPA 540/G-85/003.
U.S. Environmental Protection Agency, 1986, Superfund Public Health Evalua-
tion Manual, Office of Solid Waste and Emergency Response, USEPA, Washington,
D.C., OSWER Directive 9285.4-1, EPA 540/1-86/060.
U.S. Environmental Protection Agency, 1987, "National Primary Drinking Water
Regulations; Synthetic Organic Chemicals; Monitoring for Unregulated
Contaminants" Fed. Regist. Vol. 52:25690-25717.
U.S. Environmental Protection Agency, 1988, Guidance for Conducting Remedial
Investigations and Feasibility Studies Under CERCLA, Office of Emergency and·
Remedial Response, Office of Solid Waste and Emergency Response, USEPA,
Washington, D.C., OSWER Directive 9335.3-01.
U.S. EPA Memo, April 15, 1986, Discharge of Wastewater from CERCLA Sites into
POTWs from H. Longest II, R. Hanmer, and G. Lucero to Waste Management
Division Directors, Regions I-X.
U.S. EPA Memo, November 13, 1986, RCRA Regulatory Status of Contaminated
Ground Water from M. Williams, Office of Solid Waste to P. Tobin, Waste
Management Division, Region IV.
U.S. Office and Management and Budget, Circular No. A-94, revised 03/27/82.
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