NCD991278953_19900517_National Starch & Chemical Corp._FRBCERCLA FS_Draft Supplemental Feasibility Study Report OU-2-OCR

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DRAFT
SUPPLEMENTAL FEASIBILITY STUDY REPORT
FOR THE SECOND OPERABLE UNIT
NATIONAL STARCH AND CHEMICAL
COMPANY SITE
CEDAR SPRINGS ROAD
SALISBURY, NORTH CAROLINA
MAY 1990
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rn INTERNATIONAL TECHNOLOGY ·
CORPORATION
DRAFT
SUPPLEMENTAL FEASIBILITY STUDY REPORT
FOR THE SECOND OPERABLE UNIT
NATIONAL STARCH AND CHEMICAL COMPANY SITE
CEDAR SPRINGS ROAD PLANT
SALISBURY, NORTH CAROLINA
Prepared By
IT Corporation
Knoxville, Tennessee
May 1990
Revision No. 0
Approved: , Date: .{' /41 /90 / 1 Project Directo , Corporation
Approved: ~--£{~
Project Manager, IT Corporation
Date:
Regional Office
312 Directors Drive • Knoxville, Tennessee 37923 • 615-690-3211
ENG3130COV IT Corporation is a wholly owned subsidiary of International Technology Corporation
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CONTENTS
1.0 INTRODUCTION
2.0 SUMMARY OF THE SUPPLEMENTAL REMEDIAL INVESTIGATION
3.0 DEVELOPMENT OF REMEDIAL ACTION ALTERNATIVES FOR SOIL
3. 1 Development of General Response/Remedial
Technologies
3.2 Screening Remedial Technologies/Process Options
3.3 Development of Remedial Action Alternatives
4.0 DETAILED ANALYSES OF REMEDIAL ACTION ALTERNATIVES
4 . 1 Alternative 1 -No Action (Natural Soil Flushing)
4.2 Alternative 2 -Site Capping
4.3 Alternative 3 In Situ Soil Flushing
4.4 Alternative 4 -Excavation and Incineration
4.5 Alternative 5 -Off-Site Disposal to Secure Landfill
5.0 COMPARITIVE ANALYSIS OF ALTERNATIVES AND RECOMMENDATION OF
SELECTED ALTERNATIVE
5.1 Comparative Analysis
5.2 Recommended Alternative
6.0 REFERENCES
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ENG3130CON
TABLES
National Starch and Chemical Company Development of
Remedial Technologies for Soil Contamination
National Starch and Chemical Company Screening
Control Technologies for Soil Contamination
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1,0 INTRODUCTION
This Supplemental feasibility study (FS) is based upon the findings of the
Supplemental RI, the initial RI, and the final FS submitted September 1988. A
Supplemental remedial investigation (RI) was conducted at the National Starch
and Chemical Company (NSCC) Cedar Springs Road Site in' Salisbury, North
Carolina between October 1989 and February 1990. The final Supplemental RI
(IT Corporation, 1990) was submitted in May 1990.
The initial RI (first operable unit) (IT Corporation, 1988) was conducted at
NSCC from December 1986 through January 1988 with the final RI report
submitted in June 1988. The final FS report was submitted in September
1988. The reader is referred to the FS (IT, 1988b) for additional
information.
As directed by the Record of Decision (ROD) for the first operable unit, the
U.S. Environmental Protection Agency (EPA) required that a source control
operable unit be established. This source, or ''second operable unit,''
prompted the Supplemental RI of which the objectives were to: (1) determine
if surface water tributaries are being impacted by ground water contaminants,
(2) determine if 1,2-dichloroethane detected during the first operable unit RI
is still present in the surface water and sediment of the northeast tributary,
and (3) determine the leachability of soil contaminants within the trench area
to support the FS (1988) conclusion that natural soil flushing is effective.
The results of the surface water/sediment data indicated that the surrounding
tributaries have not been impacted by ground water contamination. The reader
is referred to the Supplemental RI report for background information. The
surface water/sediment data also indicated that the northwest and southwest
tributaries do not contain significant levels of contaminants of concern and
are not a risk to public health and environment as concluded during the
original FS. However, the northeast tributary was determined to have 1,2-
dichloroethane contamination in the surface water and sediment at two sampling
locations.
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This FS report evalua~es remedial action alternatives for the soil in the
trench area based upon findings in the Supplemental RI report for the second
operable unit (May 1990). It does not address the surface water/sediment
findings in the northeast tributary since source evaluation efforts are
continuing.
A public health evaluation has been completed on the NSCC site and will not be
repeated here. The reader is referred to the FS (September 1988) of the first
operable unit where the public health evaluation addresses the potential long-
term public health risks based upon potential exposure to chemicals in the
air, soil, surface water, and sediments. The evaluation addresses soil
contamination in the trench area in that the ground water is the only
receptor. Thus, the potential public use of the ground water is considered in
the evaluation since it is the only receptor of soil contamination.
This Supplemental FS is presented in five sections with Section 1.0 being the
introduction. Section 2.0, Summary of the Supplemental RI serves to summarize
the findings of the Supplemental RI and to bridge the Supplemental RI
conclusions into the framework for the FS. Section 3.0, Development of
Remedial Action Alternatives, represents a summary of technologies that may be
applicable in addressing contamination present in the trench area soil. 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 4.0. Final evaluation includes
technical feasibility, cost, institutional requirements, public health
protection, and environmental protection. Section 5.0 is a comparative
analysis of the alternatives presented in Section 4.0 and presents the
recommended remedial alternative for implementation at the trench area soil.
EPA will prepare a record of decision for the second operable unit based on
the final approved FS. The selected remedial alternative will be incorporated
into the current remedial design for the first operable unit.
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2.0 SUMMARY OF.THE SUPPLEMENTAL REMEDIAL INVESTIGATION
The trench area that was once used for disposal of plant wastewater has been
identified as the suspected source area. Ten boreholes (BH-06 through BH-15)
were drilled in the trench area and continuously sampled, beginning at the
surface and extending to a depth of 30 feet or to the saturated zone,
whichever was encountered first. Laboratory analysis was conducted for all
target compound list (TCL) substances, except pesticides and.PCB, and target
analyte list (TAL) substances. Rainwater was collected and used in the
toxicity characteristic leaching procedure (TCLP) on soil from borings BH-08,
a BH-08 duplicate (BH-18), BH-09, and BH-10. For each of these four samples,
both a standard TCLP and a rainwater TCLP were run for TCL and TAL substances.
Results from the TCL organic analysis showed that borings BH-09, BH-098, BH-
10, BH-11 (and duplicate BH-16), BH-12 (and duplicate BH-17), and BH-13 were
significantly contaminated with organics, especially 1,2-dichloroethane
(DCA). The TCLP analysis (organics) showed DCA in the extract from three of
the borings (BH-10, BH-8, and BH-18). There was virtually no difference
between the TCLP standard and rainwater tests.
The TAL inorganic analysis results showed that the soil within the trench area
is representative of background conditions. In addition, the extractable
concentration of inorganics from the TCLP test was compared with the ground
water cleanup criteria. The extraction was found to contain inorganic
concentrations much lower than the cleanup criteria. Based upon these two
comparisons, the inorganics in the trench area soils was not considered
contaminants. Thus, the inorganics in the soil will not be further addressed
in this FS.
The FS of the first operable unit (September 1988) concluded that contaminants
in the vadose zone are subject to natural decay and leaching from
precipitation infiltration. This Supplemental FS for the second operable unit
supports that conclusion. The Supplemental RI presented contaminant transport
modeling to evaluate the effectiveness of natural soil flushing during the
ground water remediation effort. Contaminants in the trench area subsurface
soil were predicted to leach over time by infiltrating rainwater. The
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leachate will then become captured by the ground water extraction system and
treated in the on-site pretreatment system, so that the applicable or relavant
and appropriate requirements (ARARs) at the property line will be satisfied.
Most of the organic contaminants were predicted to take 5 years to leach into
the ground water before a safe level is reached in the .soil that would not
result in future impacts on ground water. DCA was predicted to take 22 years
before a safe level is reached in the soil; however, this is still within the
projected time frame for ground water remediation which was estimated to take
20 to 30 years.
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3.0 DEVELOPMENT.OF REMEDIAL ACTION ALTERNATIVES FOR SOIL
The purpose of this section is to develop remedial action alternatives that
adequately meet the goals for protecting human health and the environment.
This section presents general response actions with a list of technology types
and process options for each action. Each technology/process option 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 4.0.
3. 1 DEVELOPMENT OF GENERAL RESPONSE/REMEDIAL TECHNOLOGIES
The various remedial technologies associated with each general response action
for soil is presented in Table 3-1. 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 upon information from the Supplemental
RI report.
3.2 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 physical
treatment technology might include process options such as soil farming,
solidification, and soil washing. 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.
3.2.1 No Action (Natural Soil Flushing)
The no-action alternative would leave contaminated soils in place. Chemicals
will migrate from the soils into the ground water by leaching caused by
infiltrating precipitation. As a result, contaminants in the unsaturated zone
would be naturally leached or biodegraded. Leached contaminants would be
extracted and treated as a part of ground water remedial efforts. This is the
only route of potential exposure for soil contamination. Also, the National
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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.
3.2.2 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
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,
contact with soils, and to limit 'construction in certain areas. This process
option is retained for further consideration.
3.2.3 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.
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
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the contaminants are only in the vadose zone or a barrier against direct
contact is needed. The cap may be of a multilayer design which is more
reliable than a single layer design because of minimal maintenance
requirements and is better 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 and is easily constructed. 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. The slurry is left in the trench and allowed to set up to
form the completed barrier.
Design parameters for slurry walls include vertical depth and horizontal
placement.
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,
compatibility with the wastes, and construction difficulties.
To effectively key the slurry wall into the impermeable bedrock at the site,
deep trenching or sealing bedrock fractures (i.e., grouting) to a depth of
greater than 90 feet would be required. Because this technology is costly and
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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 insertion of an inert,
impermeable, and continuous horizontal barrier in soil beneath the source of
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
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not exist after injection. This technology will not be considered for further
evaluation.
3.2.4 Soil Treatment Technologies
Soil treatment actions refer to excavation of contaminated soils followed by
on-site treatment. Control of dust and organic vapors during excavation may
be necessary to adequately protect human health and the environment.
Excavated soils are placed in a secure holding area prior to treatment.
Stabilization
Cementitious or silicate based additives can frequently be used to reduce the
leachability of contaminants from soils or sludges. The stabilization
chemicals are mixed with the excavated soil in a pug mill or in similar
equipment. The stabilization formula is selected so that the final waste form
will pass the Toxicity Characteristic Leaching Procedure (TCLP) and can be
either disposed of on site or in a nonhazardous waste landfill.
Stabilization can often chemically fix metals but is typically not as
effective on organics, especially the volatile organics that are common in the
soils at this site. Because the volatile organics are the contaminants of
concern, stabilization will not be considered further.
Soil Washing
Soil washing involves contacting contaminated soils with an aqueous medium to
release the contaminants into solution. The extracted contaminants can then
be either concentrated for treatment or the entire aqueous stream can be
treated. Both of these options may be preferable to direct soil treatment
because more conventional and less costly treatment processes can generally be
applied to an aqueous stream than to soils.
Soil washing is similar to soil flushing except that the process is applied to
excavated soils rather than in situ. Additional safety requirements are
needed for the excavation of contaminated soils. Transfer of contaminants
from the soil matrix to solution is accomplished in countercurrent extraction
equipment. Good mixing is necessary for adequate mass transfer. Water alone
is occasionally sufficient to release soluble organics.
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Following extraction, cleansed soils must be separated from solution. Soils
are typically settled, dewatered, and returned to the excavation area.
Separation may be complicated by clays or silts in the soil which will reduce
the performance. Given the uncertainty associated with soil washing along
with a very expensive handling requirement, this option is dismissed.
Soil Farming
Soil farming involves spreading excavated soils to allow volatile organics to
escape into the atmosphere. The soil is worked by disking until a satis-
factory level of volatiles is achieved and then replaced. This method is
ineffective for nonvolatiles. Exposing nontreated organic contaminants in an
essentially uncontrolled manner for a long period of time may be undesirable
for public health reasons. Treatment efficiencies are not well defined but
are subject to ambient temperature, precipitation, and wind, as well as soil
and contaminant type. Therefore, soil farming is removed from further
consideration.
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 oxygen, inorganic nutrients, 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
and chloride 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
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reducing the potential for enhanced biodegradation. Therefore, in situ
biodegradation is removed from further consideration.
In Situ Soil Flushing
Soil flushing is the application of a solution to contaminated soils and
collection of the leachate at well points for treatment of solubilized waste
constituents. Potential flushing solutions include acids, complexing/
chelating agents, surfactants, and water. Complexing/chelating agents and
weak acids are mainly effective in the mobilization of heavy metals but not
organics, which are the primary contaminants in the soil .
Optimum placement of a recharge basin and/or injection wells, along with
extraction wells, is critical for the successful mobilization and subsequent
collection of contaminants. Mobilized contaminants that are not recovered can
increase the environmental risk at a site. Detailed knowledge of the local
hydrogeology is required. Soil characteristics are also important.
Generally, soils with a permeability less than 10-4 cm/second are not readily
remediated by soil flushing. Variable permeability in the soil bed can create
short circuiting and increase the volume of water required. The conditions at
the site are not favorable to this method due to the nature of the fractured
bedrock zones and the low permeability of the saprolite. Also, saprolite
tends to maintain preferential flow paths in zones of previous rock
fracturing. This environment will tend to short circuit the required flow
distributions.
Although this method would require several years for soil remediation, it is
retained for further consideration.
Soil Venting
In situ soil venting involves the removal of volatile organics from the soil
matrix by mechanically drawing or venting air through the unsaturated soil
layer. The process includes a series of slotted vertical injection vents
connected by a common manifold to an injection fan. Injected air may be
heated, or steam can be introduced to enhance stripping of the contaminants.
Airborne contaminants are withdrawn by a series of slotted vertical extraction
pipes connected by a common manifold to an induced draft extraction fan.
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Contaminated air may require further treatment before it is vented to the
atmosphere. Control variables include the injection air temperature, air flow
rate, vent pipe spacing, diameter and slot interval, and duration of
treatment.
Soil parameters of interest include the permeability, porosity, moisture, and
soil ''horizons''. The presence of soil horizons can lead to short circuiting
and isolate areas of contamination from stripping. Chemical parameters of
interest include vapor pressure, octanol-water partitioning coefficient, and
solubility.
Soil venting has been shown to be an effective method for the in-place removal
of volatile organics from porous soils, although there may be limits on the
residual soil levels that can be attained. Because the soils at NSCC are
dense clays, the performance of this technology may be limited; therefore,
soil venting is removed from further consideration.
Incineration
In incineration, the organics in the soils, sludges, or liquids are destroyed
by thermal oxidation; this can be accomplished through direct contact with the
flame (from the combustion of auxiliary fuel) or by heating. The soil is
heated to a temperature of 1200 to· 1500°F. At these temperatures, almost all
the organics are vaporized and at least partially destroyed through oxidation
and pyrolysis reactions. The traces of organics or products of incomplete
combustion that survive the soil heating process are destroyed by additional
exposure (typically 2 seconds) to temperatures of 1800 to 2200°F. The off-gas
from the thermal destruction process is treated to remove particulates and any
acid gases that are produced by the combustion of the organics in the soil or
by the combustion of the auxiliary fuel. Many incineration systems are
available; all heat the wastes and clean up the combustion products, but each
system uses different equipment or mechanical approach to accomplish this same
basic process.
Incineration has a high capital and moderate energy and operating cost, all of
which are dependent on the volume of soil to be incinerated. Treatment by
incineration is generally used for solids that contain especially toxic
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compounds. These compounds include PCBs, dioxins, pesticides, herbicides, and
other acutely hazardous organic chemicals. Incineration is a commercial
technology and can be reliably implemented. Because this is a proven
technology, it will be retained for further consideration.
Thermal Desorption
Thermal desorption is a new technology for treating soils or sludges that are
contaminated by organics. In this process, the contaminated soil is heated to
a temperature (typically 300 to 1000°F) sufficient to volatilize the hazardous
organics adsorbed on the sludge. These temperatures are not high enough to
destroy most organic compounds; they must be destroyed by further treatment of
the vapor driven off the soils. These vapors can be treated by fume
incineration or by condensation followed by off-site disposal, incineration,
or chemical treatment. Thermal desorption has been demonstrated on soils
contaminated with volatile organic compounds (VOCs), with 2,4-D/2,4,5-T
herbicides (including dioxins), and on sediments that contain PCBs. Thermal
desorption is not a practical metals removal technology. Thermal desorption
can easily remove the volatile organics that contaminate the soil at this
site.
Thermal desorption is a viable option for soil remediation. However, thermal
desorption systems are not currently cost competitive with incineration due to
their lower throughput, therefore, thermal desorption is removed from further
consideration.
3.2.5 Soil Excavation/Disposal
On-Site Landfill
Increasing regulatory control of landfilling of hazardous substances makes
this alternative steadily more expensive and difficult to implement. Sending
hazardous residuals off site can transfer liability to a new site outside the
control of the waste owner. It is typically the last alternative for wastes
not amenable to other treatment alternatives. Landfilling is a potential
technology for the soils.
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Off-site Treatment, Storage, Disposal Facility
The off-site treatment, storage, and disposal (TSD) facility will be evaluated
as a possible option for the disposal of excavated soils. This is in
accordance with rs guidance requiring that the off-site disposal option be
evaluated.
3.2.6 Screening Evaluation Summary
A summary of all remedial technologies and associated process options
evaluated is presented in Table 3-2.
3.3 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.
3.3. 1 No Action (Natural Soil Flushing)
The no action alternative as discussed in Section 3.2. 1 is required by the NCP
to be considered during the rs. This action will remain as a stand-alone,
site-wide alternative, This action is identified as Alternative 1.
3.3.2 Institutional Actions
Deed restrictions is the only retained option for this general response
action. This option will be combined with other technologies to provide
additional protection and to verify effectiveness of a particular alternative.
3.3.3 Containment
The only retained option for the general response action of containment is
capping. 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 soil remediation. It would be preferable to leave the area
uncapped during the ground water remediation effort to promote percolation of
precipitation so that any remaining contaminants can be removed from the soil
by natural flushing action. Therefore, capping will be considered a viable
option for soil remediation after the ground water extraction program is
complete. This approach is identified as Alternative 2.
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3.3.4 Soil Actions
In Situ Soil Flushing
The alternatiuve of in situ soil flushing is the only soil treatment
technology retained. This action is identified as Alternative 3.
Excavation/Treatment Actions
The process option of incineration was retained as a viable technology for
soil remediation. Excavation followed by incineration will be evaluated and
is identified as Alternative 4.
Excavation/Disposal Actions
One alternative is formulated by considering the options for off-site
disposal. Alternative 5 will consist of excavation and transporting soil to
an off-site, RCRA-approved landfill.
ENG31303 3-11
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Environmental
Media
Soi I
ENG31303A
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It!! --Table 3-1. National Starch and Chemical Company Development of
Remedial Technologies for Soi I Contamination
General Response Actions
No action (Natural Soi I Flushing)
Institutional actions:
Access restriction
Containment actions:
Containment
Excavation/Treatment Actions:
Excavation/treatment
In situ treatment
Disposal/Excavation
Remedial Technology Types
No action
Fencing
Deed restriction
Capping
Vertical barriers
Horizontal barriers
Surface controls
Removal technologies
Treatment Technologies:
Physical treatment
In situ treatment
Thermal treatment
Disposal technologies
·Process Opt ions
Clay cap, multi layered
cap, slurry wal I, sheet
pi I i ng I i ners, grout
injection, diversion/
collection, grading, soil
stabi I ization
Excavation
Soi I washing, soi I farming
solidification, fixation
Soi I flushing, soi I venting,
subsurface bioreclamation
Incineration
Thermal desorption
Off-site RCRA faci I ity
On-site landf i 11
-
--
Soi I
General Response
Action
No action
Institutional
actions
Containment
ENG31303B
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Remedial Technology
Natural soi I f 1ushing
Access restrictions
Cap
Vertical barriers
05/14/90 DRAFT I NPNE
ea ail -
Table 3-2. ~ationa1 Starch and Chemical Corporation Screening
Control Technologies for Soi I Contamination
Process Option
Not app Ii cab I e
Deed restrictions
Fencing
Clay and soil
Multi layered cap
SI urry wa I I
Grout curtain
Effectiveness
N/A
Effective in I imiting
use of trench area
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
lmplementabi I ity
N/A; wi 11 I ikely require long-
term moniioring
Legal requirements
Easily implemented; restriction
on future land use
Easily implemented;
restriction on future land use
Difficult to verify continuity
of slurry or backf i I I
Di ff i cu I t to verify continuity
of wal I; must tie into
impervious zone
--
Cost
Low O&M ( I ong-
term monitoring)
Neg I igible
Low capital,
low maintenance
-
Status
Retained
Retained
Dismissed
Retained
Moderate capital, Retained
low maintenance
High capital,
low O&M
High capital,
low O&M
Dismissed
Dismissed
- -
Soi t
General Response
Action
Containment
(continued)
Remedial Technology
Excavation/ Removal
Treatment Action
Physical treatment
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Process Option
Sheet pi le
Excavation
Soi I washing
Soi I farming
So I id if l cation/
fixation
Table 3-2. (Continued)
Effectiveness
Not effective because of
fractured bedrock
Effective for removal of
contaminants in soi I, but
requires disposal
Water can be effective
since votati les of concern
are highly soluble.
Requires excavation and
the treatment of water.
Clayey soi I can hinder
removal efficiencies. Poor
track record; may not treat
to desired levels
Effectiveness is dependent
on ambient temperatures,
precipitation and wind.
May not conform to air
release regulations for
volatile compounds.
Not an effective method for
organic compounds.
-
lmplementabi I ity
Oiff icult to key to bedrock; no
excavation required; I imited to
50 feet
Readily implemented with
conventional construction
equipment
Implemented using
commercial !y avai I able
mining and chemical
processing equipment
Easily implemented. Requires
excavation of contaminated
soi Is and spreading over
large area with surface
water control.
Readily implemented by
excavating and mixing soi I
with the additive
--
Cost
High capital,
low O&M
High capital,
low O&M
High capital,
Moderate O&M
High capital,
high 0&M
-
Status
Dismissed
Retained
Dismissed
Dismissed
Moderate capital I Dismissed
low O&f.1
---
Soi I
General Response
Action
Excavation/
disposal action
ENG31303B
Remedial Technology
In situ treatment
Thermal treatment
Thermal desorption
Off-site disposal
05/14/90 DRAFT I NPNE
Process Option
Subsurface
bioreclamation
Soil flushing
Soi I venting
Rotary k i t n
incinerator
RCRA facility
iiii iiil
Table 3-2. (Continued)
Effectiveness tmplementabi I ity
Effectiveness is dependent Readily implemented by
on soi I uniformity (i.e. grain horizontal irrigation. May
size, porosity, Ph, etc,) require bench-scale testing;
poor track record for this
type of geologic setting
Effectiveness is dependent on Not readily implemented in
soi I uniformity and abi I ity to clayey soi ls would require
capture the leachate
Not an effective method for
tight clayey soi Is
Effectiveness is dependent
on operation of incinerator
Effective on volatile
organic compounds
Effective and reliable, but
requires transportation
numerous injection/extraction
we I Is and sever a I years of
flushing
Not readily implemented in
clayey soi Is, would require
pressurized air injection
Clayey soi Is may require longer
residence time thereby increas-
ing O&M. ,:O.va i I ab i I i ty of
incinerators is questionable.
Implementation may require
testing
Permits required
---
Cost Status
Moderate capital, Dismissed
moderate O&t:1
Moderate capital, Retained
moderate O&M
Moderate capital, Dismissed
moderate O&M
High capital,
low O&M,
high or
moderate
High capita!,
moderate O&M
High capital,
high 0&M
Retained
Dismissed
Retained
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4. 0 DETAI_LED ANALY_SES OF REMEDIAL ACTION ALTERNATIVES
This section provides a separate detailed analysis for each alternative
defined in Section 3.3. The detailed analysis will include a technical
evaluation, institutional evaluation, public health evaluation, environmental
impacts evaluation, and a cost evaluation. Provisions for a re-evaluation of
the feasible alternatives for every 5 years have been included in the
operation and maintenance costs.
4. 1 ALTERNATIVE 1 -NO-ACTION (NATURAL SOIL FLUSHING)
The no-action alternative will allow for the naturally occurring leaching or
cleaning of soil in conjunction with ground water remediation. A deed
restriction will be filed identifying the areas of contamination as defined by
the Supplemental RI report.
The deed restriction will prevent property transfers to uninformed purchasers
and will limit future utilization of the property. The deed restrictions are
easily implemented by processing the restrictions through a local attorney and
the Rowan County or City of Salisbury Register of Deeds.
The trench disposal areas as defined in the Supplemental RI report do not
present a health risk through the direct contact of surface soils as discussed
in the Public Health Evaluation (September 1988 FS). Therefore, access
restriction to this area is not required. It should be noted that the trench
area lies well within the NSCC property away from any frequented areas.
Contamination (over time) will be reduced because of biodegradation, leaching,
and volatilization of contaminants.
Technical Evaluation
The no-action alternative does not provide additional mitigation to the soil
contamination beyond the natural processes that are currently taking place.
The soil contamination can only manifest itself through the ground water
transport mode.
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Any· residual contamina_nts in th_e unsaturated zone will be leached naturally by
precipitation infiltration and then biodegraded. Contaminant transport
modeling, as presented in the Supplemental RI, predicted that most compounds
will leach into the ground water within the projected time frame for ground
water remediation. This leaching process will be hastened by not covering the
trench area with a cap in order to maximize infiltration. This alternative,
in conjunction with ground water remediation, provides an effective method to
treat soil and ground water contaminants.
Institutional Evaluation
The soil, by definition, is not a hazardous waste and does not require
treatment beyond its ability to threaten the public health or environment.
Public Health Evaluation
The public health evaluation for no remedial action is presented in the
September 1988 FS (IT, 1988b). Public health will not be at risk unless the
soil is excavated or additional contaminants from the soil migrate into the
ground water and the contaminant plume migrates past the property line at
levels in excess of ARARs. Ground water will be controlled so that ARARs at
the property line will be satisfied.
Environmental Impact Evaluation
The impact on the environment by implementing the no-action alternative is
discussed in the September 1988 FS.
Cost Evaluation
The capital costs associated with the no-action alternative are the attorney
fees for processing the deed restrictions. The operation and maintenance
costs associated with this alternative are for resampling and evaluating the
reduction of contaminants in the soil every five years.
Capital Costs
Deed restriction, lawyer fees $1,000
Subtotal $1,000
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Operation and Maintenance Costs
Soil sampling every five years
(30 years, present worth)
Present Worth
4.2 ALTERNATIVE 2 -SITE CAPPING
Subtotal
PW=
PW=
$150,000
$150,000
$1,000 + $150,000
$151,000
This alternative involves the capping of all past trench disposal areas at the
site. This alternative will reduce the rate of migration of contaminants into
the ground water from the unsaturated soils that underlie the trench areas.
Because low permeability clay is prevalent throughout the NSCC property, a clay
cap will be constructed from soil excavated on site. The cap construction will
consist of:
• Native soil used to bring the area to the appropriate grade and
establish a foundation for the final cover
• A 2-foot layer of on-site clay will be placed on top of the native
soil foundation and properly compacted.
• Topsoil will be placed on top of the compacted clay to support
vegetation.
• Revegetation that consists of seeding, fertilizing, and mulching will
be performed on all disturbed areas.
• Drainage swales and ditches will be constructed as necessary to
prevent run-on and promote runoff from the capped areas.
The trench area is approximately 300,000 square feet as estimated from the
boundary established in the RI.
Technical Evaluation
Because of its low permeability (<10-7 cm/second) capping will significantly
reduce infiltration and, therefore, likely reduce the rate of transport of
additional contaminants into the ground water. However, it would be
advantageous for contaminants in the unsaturated zone to be leached into the
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ground water as soon as practical while ground water is being pumped.
Constructing a cap over any contaminated soil will lengthen the time for this
leaching process to occur.
Construction and maintenance of a cap is easily implemented. Maintenance will
consist of periodic inspections for erosion, subsidence, and ponding.
Material and equipment for cap construction are readily available.
Institutional Evaluation
The cap is not specifically required by waste management regulations.
Public Health Evaluation
Public health will not be at risk unless additional contaminants from the soil
migrate into the ground water. The contaminant migration from the soils to
the ground water is controlled by capping but not eliminated. This
alternative does not reduce the soil contamination or ground water
contamination; it will increase the time required for the contaminants to
migrate from the soil into ground water. This may serve to lengthen the time
for any ground water remediation.
Environmental Impact Evaluation
Because the soil does not pose a r·isk to the public health or environment,
this alternative will not impact the environment.
Cost Evaluation
The capital cost associated with this alternative is the construction of the
multilayered cap, which is estimated to take 1 month. The operation and
maintenance costs is the periodic inspection of the cap. The capital cost,
O&M costs, and present worth costs are presented below.
Capital Cost
Cap design
Grade site for cap foundation -16,000 c.y.
at $6.30/c.y.
Construct clay cap -27,800 c.y. at $7.50/c.y.
Topsoil -7000 c.y. at $6.30/c.y.
Seeding and mulching
Subtotal
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$ 30,000
101,000
209,000
44,000
30,000
$414,000
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Operation and Maintenance Costs
Periodic inspection of cap
Subtotal
Present Worth
PW= 414,000 + 1,000 (PIA, 10 percent, 30 year)
PW= 414,000 + 1,000 (9.427)
PW= 423,000
4.3 ALTERNATIVE 3 -IN SITU SOIL fLUSHING
$ 1 000/yr
$ 1,000/yr
This alternative involves in-place flushing of the trench area soils during
the ground water remediation effort. Enhanced flushing can hasten the time
for reduction of residual contamination on the soil where the soil no longer
represents a threat to ground water.
The water for flushing would be distributed into the soil through one or two
infiltration trenches and injection wells in the original trench area. The
water would then percolate through the underlying vadose zone soils into the
saprolite aquifer. The leachate would be extracted by the downgradient deep
well extraction system that will be installed to control the existing ground
water plume. The extraction system would be finalized during the RD. The
water used for flushing the soil would preferably come from the ground water
extraction or treatment system. Water from Grants Creek, an uncontaminated
upgradient well, or potable (city) water could be used if NSCC could not
obtain a permit to reinject site ground water. The soil flushing system may
need to operate for several years to effectively remediate the trench area
soils. It is likely that the soil flushing system would remain in operation
for the same period as the ground water remediation system.
Technical Evaluation
Although the site conditions for this technique are not favorable, in situ
flushing could eventually lower residual soil contaminant concentrations to
levels that would not threaten ground water quality.
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Institutional Evaluation
Reinjection of treated ground water into the trench area will require a
nondischarge permit from the North Carolina Department of Environment, Health,
and Natural Resources. Obtaining this permit will require 6 months to year
and will require a variance from the state's water quality standards for
reinjection.
Public Health Evaluation
As mentioned previously, public health will not be at risk unless additional
contaminants from the soil migrate into the ground water. Contaminant
migration from the soils to the ground water will be reduced significantly by
this alternative. This alternative, in combination with ground water
remediation, will meet the ARARs at the property line, as a stand-alone
alternative, this does not meet the standards.
Environmental Impact Evaluation
This alternative will lower the residual contamination in the soil.
Cost Evaluation
The capital costs associated with in situ soil flushing are the infiltration
trenches and the extraction well system. The design of these systems will not
be finalized until the RD, but for cost estimation for comparison to other
alternatives, it is assumed that 800 linear feet of infiltration trenching and
50 (6-inch diameter) injection wells will be adequate. Leachate migration
will be captured by the ground water extraction system. The capital costs,
O&M costs, and present worth of these costs for in situ soil flushing are
presented below.
Costs for In Situ Soil Flushing
Capital Cost
System design and permitting
Infiltration trenching
Injection wells
ENG31304
05/17/90 DRAFT 2 NE
Subtotal
4-6
$ 30,000
65,000
300,000
$395,000
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Annual Operation and Maintenance Costs
Pump and well maintenance
Infiltration trench reworking
Soil sampling every 5 years
(30 years, present worth)
Subtotal
Subtotal
Present Worth for In Situ Soil flushing
$15,000/yr
10,000/yr
$25,000/yr
$150,000
$150,000
PW= $395,000 + $25,000 (PIA, 10 percent, 10 years) + $150,000
PW= $395,000 + $25,000 (9.427) + $150,000
PW= $395,000 + $236,000 + $150,000 = $781,000
4.4 ALTERNATIVE 4 -EXCAVATION AND INCINERATION
This alternative involves on-site incineration of excavated soils from the
trench area. This process is effective for both volatile and nonvolatile
contaminants. Assuming all soils under the trenches have contaminant
concentrations similar to the trench samples collected during the RI and
Supplemental RI, the approximate volume of soils to be remediated is 250,000
cubic yards.
This alternative will require the following site preparation work: excavation
of contaminated materials, staging. of materials before and after incineration,
and placement of the incinerator.
A diked, lined staging area will be required for excavated soils prior to
incineration. Storage space for 3 days' worth of soil to be incinerated will
be provided because excavation rates are expected to exceed incineration
rates. Incinerated soil will be stored in open sites prior to sampling for
residual contamination. Soils will then be replaced in disposal areas.
Given the large volume of soil considered for remediation (>300,000 tons),
with light organic contamination and soil moisture content less than 30
percent, the soil is ideal for incineration using a mobile on-site
incinerator.
The soil can be incinerated at rates up to 20 tons/hour. Emissions and
ENG31304 4-7
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effluents will be treated, monitored, and controlled to levels well within
current regulatory limits.
Incinerated material will be analyzed prior to replacement in disposal areas
to ensure that remediation levels have been achieved. After replacing the
incinerated soils, the disposal areas will be given topsoil and revegetated.
Technical Feasibility
Incinerators have achieved destruction and removal efficiencies of 99-9999
percent at feed rates between 15 to 20 tons per hour with particulate
emissions averaging 3.89 milligrams per dry standard cubic meter (0.08 grains
per dry standard cubic foot).
Institutional Evaluation
Permits may be required by the regulatory agencies. A trial burn may also be
required once the unit is assembled on-site.
Public Health Evaluation
Primary concerns for safety are during the excavation of the soils. Personnel
protective equipment will be provided to workers to address this potential
risk. The exposure of the contaminated soils to the air may cause increased
volatilization of organics and direct contact to precipitation, which will
enhance mobilization of contaminants.
Air impacts from the incinerator are mitigated by an emission control system.
Environmental Impact Evaluation
This alternative will cause a significant release of volatile organics and
potentially contaminated dust during excavation and staging.
Cost Evaluation
The capital costs associated with this alternative are the excavation of the
contaminated soils, site preparation for the incinerators and soil staging
area, and mobilization and demobilization of incinerator. Operation and
maintenance costs will average between $100 to $200 per ton.
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Capital Costs
Excavation and staging of soil
backfilling and grading
Operation and maintenance
337,500 tons
Present Worth
Subtotal
PW= $1,500,000 + $50,625,000 = $52,125,000
$1,500,000
33,750,000 -67,500,000
$50,625,000
4.5 ALTERNATIVE 5 -OFF-SITE DISPOSAL TO SECURE LANDFILL
This alternative includes excavating contaminated soil ,iithin the trench area
and transporting to a secure landfill for disposal. It is estimated that
there are 250,000 cubic yards of contaminated soil within the trench area.
Technical Evaluation
This alternative is technically feasible. Note that this alternative only
addresses the soil in· the unsaturated zone and that contaminated soil and
ground water exists in the saturated zone as well. Landfilling such a large
volume of soil is not considered to be practical.
Institutional Evaluation
No special permits are required beyond typical waste manifesting.
Public Health Evaluation
Ground water remains the public health concern for this site. This
alternative does not add any degree of safety beyond that offered by ground
water control and treatment because the soil itself does not pose a public
health risk.
Environmental Impact Evaluation
Soil does not pose an environmental risk, and this alternative in turn does
not mitigate any environmental risk.
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Cost Evaluation
250,000 c.y. soil (337,500 tons of soil)
Excavation
Transportation
Disposal
Site restoration
ENG31304
05/17/90 DRAFT 2 NE
Total
4-10
$1,250,000
16,400,000
33,750,000
500 000
$51,900,000
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5.0 COMPARATIVE ANALYSIS OF ALTERNATIVES AND
RECOMMENDATIONS OF SELECTED ALTERNATIVE
This section provides a comparative analysis of the alternatives presented in
Section 4.0 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 4.0 (i.e.,
technical evaluation, institutional evaluation, public health evaluation,
environmental impact evaluation, and cost evaluation).
5. 1 COMPARATIVE ANALYSIS
Technical Evaluation
All alternatives are technically feasible. No option is more technically
sound than the other. Capping could lengthen the time required to treat
ground water by inhibiting the rate of contaminant leaching or biodegrada-
tion. The practical merits of transporting this volume of soil to a secure
landfill are certainly questionable because the soil does not pose a risk to
the public health or environment.
Institutional Evaluation
From an institutional perspective, no alternative poses any real problems or
advantages over the other. The massive trucking of contaminated soil through
residential areas to main highways may cause local opposition. Leaving
contaminated soil in place should not pose a problem as long as deed
restrictions are instituted for this property.
Public Health and Environmental Evaluation
As previously stated, the soil does not pose a public health or environmental
problem. Consequently, no risks are mitigated by any of the alternatives
because no risk is present.
ENG31305 5-1
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Cost Evaluation
The costs for the five alternatives range from $150,000 to over $25 million.
By leaving the contaminated soil in place, there are no risks posed by the
site. In-situ or natural soil flushing would enhance the rate of migration of
contaminants into the ground water which will be controlled during the ground
water remediation effort. In-situ soil flushing is not cost competitive with
natural soil flushing. Because no risks are posed by the site, the most cost-
effective alternative is the no-action alternative.
5.2 RECOMMENDED ALTERNATIVE
Based on the above evaluations, Alternative 1 (the no-action alternative, or
natural soil flushing) 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 2, 3, 4,
or 5.
The primary concern at this site is ground water. The only way soil
contamination can manifest itself is through leaching into the ground water
system. If the ground water is to be controlled and treated to prevent
releases off the property, then the only potential exposure pathway has been
addressed. By allowing natural leaching and biodegradation of organic
contaminants to occur, the contamination in the soil is remediated coincident
with ground water remediation. This natural phenomena is expedited by not
isolating the vadose zone with a cap or cover.
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. 6.0 REFERENCES
IT Corporation, 1988, Remedial Invesitgation Report, National Starch and
Chemical Company Site, Cedar Springs Road Plant, Salisbury, North Carolina.
IT Corporation, 1988b, Feasibility Study Report, National Starch and Chemical
Company Site, Cedar Springs Road Plant, Salisbury, North Carolina.
IT Corporation, 1990, Supplemental Remedial Investigation Report, National
Starch and Chemical Company Site, Cedar Springs Road Plant, Salisbury, North
Carolina.
ENG31306 6-1
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