FEASIBILITY STUDY REPORT
STANDARD CHLORINE OF DELAWARE SITE
OPERABLE UNIT 3 (OU-3)
NEW CASTLE COUNTY, DELAWARE
Prepared for:
U.S. Environmental Protection Agency Region 3
1650 Arch Street
Philadelphia, PA 19103
EPA Contract Number: EP-S3-07-05
Work Assignment Number: 002RICO03H6
July 2009
vHGL
InC 1835 Market Street, Suite 1210 Philadelphia, PA 19103
^^^« Phone: (215)636-0667 Fax: (215)636-0668
www.hgl.com
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TABLE OF CONTENTS
EXECUTIVE SUMMARY ES-1
1.0 INTRODUCTION 1-1
1.1 PURPOSE AND ORGANIZATION OF THE REPORT 1-1
1.2 SITE BACKGROUND 1-2
1.2.1 Site Location and Description 1-2
1.2.2 Site Operational History 1-3
1.3 ENVIRONMENTAL SETTING 1-4
1.3.1 Site Topography and Surface Drainage 1-4
1.3.2 Geology 1-4
1.3.3 Hydrogeology 1-5
1.4 PREVIOUS SITE INVESTIGATIONS AND REMEDIAL RESPONSES 1-8
1.4.1 Introduction 1-8
1.4.2 Catch Basin 1 Release and Related Remedial Activities 1-9
1.4.3 1981 Release and Related Remedial Activities 1-9
1.4.4 1986 Release and Related Remedial Activities 1-10
1.4.5 1991-1992 Remedial Investigation and Feasibility Study 1-10
1.4.6 1999 Initial PRP Remedial Design Sampling 1-12
1.4.7 2002-2004 Remedial Design and Remedial Investigation Activities .. 1-12
1.4.8 Interim Groundwater Remedy 1-14
1.4.9 Ongoing Sampling Activities 1-15
1.5 NATURE AND EXTENT OF CONTAMINATION 1-15
1.5.1 On Facility Contamination 1-15
1.5.2 Northern Area Contamination 1-20
1.6 CONTAMINANT FATE AND TRANSPORT 1-20
1.6.1 Air Migration 1-20
1.6.2 Surface Runoff and Migration 1-21
1.6.3 Groundwater Migration 1-22
1.7 SUMMARY OF BASELINE RISK ASSESSMENT 1-22
1.7.1 Human Health Assessment 1-22
1.7.2 Ecological Risk Assessment (Surface Soil) 1-24
2.0 REMEDIAL ACTION OBJECTIVES 2-1
2.1 REMEDIAL ACTION OBJECTIVES 2-1
2.2 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS . 2-1
2.3 DETERMINATION OF REMEDIATION GOALS AND DESCRIPTION
OF CONTAMINATED MEDIA 2-8
2.3.1 Derivation of Risk-Based Preliminary Remediation Goals 2-8
2.3.2 Volume Estimates 2-13
U.S. EPA Region 3
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TABLE OF CONTENTS (continued)
3.0 IDENTIFICATION AND SCREENING OF TECHNOLOGY TYPES AND
PROCESS OPTIONS 3-1
3.1 GENERAL RESPONSE ACTIONS 3-1
3.2 IDENTIFICATION AND SCREENING OF POTENTIALLY
APPLICABLE TECHNOLOGIES 3-2
3.3 EVALUATION OF POTENTIAL REMEDIAL TECHNOLOGIES 3-2
3.3.1 No Action 3-2
3.3.2 Institutional Controls 3-3
3.3.3 Containment 3-4
3.3.4 Treatment 3-8
3.3.5 Removal and Disposal TPOs 3-18
3.3.6 Monitoring of Site Conditions and Contaminant Levels 3-21
3.4 SUMMARY OF TREATMENT TECHNOLOGIES AND SELECTION
OF REPRESENTATIVE PROCESS OPTIONS 3-21
4.0 DEFINITION AND SCREENING OF REMEDIAL ALTERNATIVES 4-1
4.1 DEFINITION OF ALTERNATIVES 4-1
4.1.1 Alternative 1A: No Action 4-1
4.1.2 Alternative IB: Limited Action 4-1
4.1.3 Alternatives 2A - 2D: Containment 4-2
4.1.4 Options for Excavated Soil from Surface Cap Construction 4-6
4.1.5 Alternatives 3A - 3D: In Situ Treatment 4-9
4.2 SCREENING OF REMEDIAL ALTERNATIVES 4-12
5.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES 5-1
5.1 EVALUATION CRITERIA 5-1
5.1.1 Overall Protection of Human Health and the Environment 5-1
5.1.2 Compliance with Applicable or Relevant and Appropriate
Requirements 5-2
5.1.3 Long-term Effectiveness and Permanence 5-2
5.1.4 Reduction of Toxicity, Mobility or Volume 5-2
5.1.5 Short-Term Effectiveness 5-2
5.1.6 Implementability 5-2
5.1.7 Cost 5-2
5.1.8 State Acceptance 5-3
5.1.9 Community Acceptance 5-3
5.2 DEFINITION AND INDIVIDUAL ANALYSIS OF ALTERNATIVES 5-3
5.2.1 Alternative 1A: No Action 5-3
5.2.2 Alternatives 2A, 2B, and 2C: Common Elements 5-4
5.2.3 Alternative 2A: Surface Cap 5-5
5.2.4 Alternative 2B: Surface Cap with Soil Vapor Extraction 5-11
5.2.5 Alternative 2C: Surface Cap with In Situ Thermal Desorption 5-15
U.S. EPA Region 3
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TABLE OF CONTENTS (continued)
6.0 COMPARATIVE ANALYSIS OF ALTERNATIVES 6-1
6.1 OVERALL PROTECTION OF HUMAN HEALTH AND THE
ENVIRONMENT 6-1
6.2 COMPLIANCE WITH ARARS 6-1
6.3 LONG-TERM EFFECTIVENESS AND PERMANENCE 6-1
6.4 REDUCTION OF TOXICITY, MOBILITY OR VOLUME 6-2
6.5 SHORT-TERM EFFECTIVENESS 6-2
6.6 IMPLEMENTABILITY 6-3
6.7 COST 6-3
6.8 STATE AND COMMUNITY ACCEPTANCE 6-4
6.9 PREFERRED ALTERNATIVE 6-4
7.0 REFERENCES 7-1
LIST OF APPENDICES
Appendix A PRO Detail Tables
Appendix B SCO NPDES Permit Equivalence Documentation from DNREC
Appendix C Remedial Technology Cost Estimates
• Appendix C-l - Surface Cap (Multilayer)
• Appendix C-2 - Surface Cap (Cement)
• Appendix C-3 - Surface Cap (Asphalt)
• Appendix C-4 - Soil Vapor Extraction
• Appendix C-5 - In Situ Thermal Desorption
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LIST OF TABLES
Table 2.1 Applicable or Relevant and Appropriate Requirements (ARARs) for Standard
Chlorine of Delaware Operable Unit 3
Table 2.2 On Facility Contaminants of Concern and Preliminary Remediation Goals for
Standard Chlorine of Delaware Operable Unit 3
Table 2.3 Off Facility Contaminants of Concern and Preliminary Remediation Goals for
Standard Chlorine of Delaware Operable Unit 3
Table 2.4 Estimated Extent of Site Contamination for Standard Chlorine of Delaware
Operable Unit 3
Table 2.5 Estimated Extent of Site Dioxin Contamination for Standard Chlorine of
Delaware Operable Unit 3
Table 3.1 Identification and Preliminary Screening of Soil and Soil Gas Technologies For
Standard Chlorine of Delaware Operable Unit 3
Table 3.2 Evaluation and Screening of Technology Process Options (TPOs) for Standard
Chlorine of Delaware Operable Unit 3
Table 4.1 Summary of Remedial Alternatives for Standard Chlorine of Delaware Operable
Unit 3
Table 4.2 Summary of Remedial Alternatives for Standard Chlorine of Delaware Operable
Unit 3
Table 5.1 Individual Evaluation of Remedial Alternatives for Standard Chlorine of
Delaware Operable Unit 3
LIST OF FIGURES
Figure 1.1 Site Location
Figure 1.2 Site Layout
Figure 1.3 Approximate Extent of OU-3
Figure 1.4 Soil and Soil Gas Sampling Locations
Figure 2.1 Locations of Samples with Contaminant Concentrations Exceeding PRGs
Figure 2.2 Locations of Samples with Dioxin Concentrations Exceeding PRGs
Figure 4.1 Projected Extent of Surface Capping and Treatment Areas
Figure 5.1 Typical Multilayer Cap Design Schematic
Figure 5.2 Typical Asphalt and Concrete Cap Schematic
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LIST OF ACRONYMS AND ABBREVIATIONS
AE assessment endpoint
amsl above mean sea level
ARAR applicable or relevant and appropriate requirements
bgs below ground surface
BLRA Baseline Risk Assessment
BTAG Biological Technical Advisory Group
BTEX benzene, toluene, ethylbenzene, and xylene
BTF biotransfer factor
CAA Clean Air Act
CCR Certified Construction Reviewer
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
CERCLIS Comprehensive Environmental Response, Compensation, and Liability
Information System
COC chemicals of concern
COPC chemicals of potential concern
CTE central tendency exposure
CWA Clean Water Act
DDD dichlorodiphenyldichloroethane
DDE dichlorodiphenyldichloroethylene
DDT dichlorodiphenyltrichloroethane
DNAPL dense non-aqueous phase liquid
DNREC Department of Natural Resources and Environmental Control
DOT Department of Transportation
DRBC Delaware River Basin Commission
DRGHC Delaware Regulations Governing Hazardous Substance Cleanup
DRGHW Delaware Regulations Governing Hazardous Waste
DSWA Delaware Solid Waste Authority
Eco-SSL Ecological Soil Screening Level
EPA U.S. Environmental Protection Agency
EPC exposure point concentration
ER electrical resistivity
ERT emergency response team
ET evapotranspiration
FFS Focused Feasibility Study
FML flexible membrane liner
FRTR Federal Remediation Technologies Roundtable
FS Feasibility Study
GAC granular activated carbon
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LIST OF ACRONYMS AND ABBREVIATIONS (continued)
GETS groundwater extraction and treatment system
GRA General Response Actions
HI hazard index
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HHRA Human Health Risk Assessment
HRS Hazardous Ranking System
HSCA Hazardous Site Cleanup Act
1C institutional control
IGR Interim Groundwater Remedy
ISCO in situ chemical oxidation
ISTD in situ thermal desorption
ITRC Interstate Technology and Regulatory Council
LDR land disposal restrictions
LOAEL lowest observed adverse effect level
LTTD low temperature thermal desorption
ME measurement endpoint
mg/kg milligrams per kilogram
MPRSA Marine Protection, Research, and Sanctuaries Act
NAPL non-aqueous phase liquid
NCP National Contingency Plan
NOAEL no observed adverse effect level
NPDES National Pollutant Discharge Elimination System
NPL National Priorities List
O&M operation and maintenance
ORNL Oak Ridge National Laboratory
OU Operable Unit
PAHs polycyclic aromatic hydrocarbons
PCBs polychlorinated biphenyls
PCE tetrachloroethene
PID photoionization detector
PPE personal protective equipment
PRG Preliminary Remediation Goal
PRP potentially responsible party
RA Remedial Assessment
RBC risk based concentration
RAGS Risk Assessment Guidance for Superfund
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LIST OF ACRONYMS AND ABBREVIATIONS (continued)
RAO Remedial Action Objectives
RCRA Resource Conservation and Recovery Act
RD Remedial Design
RFH radio frequency heating
RGO Remedial Goal Objectives
RI Remedial Investigation
RME reasonable maximum exposure
ROD Record of Decision
SARA Superfund Amendments and Reauthorization Act
SB soil boring
SCO Standard Chlorine of Delaware Site
SDWA Safe Drinking Water Act
SSL Soil Screening Level
SVE soil vapor extraction
SVOCs semivolatile organic compounds
TAL Target Analyte List
TBC to be considered
TCDD 2,3,7,8-tetrachlorodibenzo-p-dioxin
TCE trichloroethylene
TCL Target Compound List
TEQ Toxicity Equivalent
THQ target hazard quotient
TOC total organic carbon
TPO Technology Process Option
TRV toxicity reference value
TSCA Toxic Substances Control Act
TSSA temporary soil staging area
USGS U. S. Geological Survey
VOCs volatile organic compounds
WWTP wastewater treatment plant
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FEASIBILITY STUDY REPORT FOR
STANDARD CHLORINE OF DELAWARE SITE
OPERABLE UNIT 3 (OU-3)
NEW CASTLE COUNTY DELAWARE
EXECUTIVE SUMMARY
This Feasibility Study (FS) Report has been developed for Operable Unit 3 (OU-3) of the
Standard Chlorine of Delaware (SCD) Site under Contract Number EP-S3-07-05 with Region 3
of the U.S. Environmental Protection Agency (EPA).
The purpose of this FS Report is to develop and evaluate remedial alternatives that may be
feasible for addressing potential risks to the human health and the environment posed by
contaminated soils and soil gas at the SCD site. This FS was conducted in accordance with the
National Contingency Plan (NCP) and the current USEPA Superfund guidance, using the
following approach:
1) Site history and setting, as well as current site characteristics, were summarized.
2) Remedial action objectives were established, including identification of applicable or
relevant and appropriate requirements (ARARs). Site-specific Preliminary Remedial
Goals (PRGs) were developed, and the areas and volumes of soil requiring remediation
were estimated.
3) Technologies with the potential to remediate soil and soil gas at the site were identified
and screened.
4) The technologies retained after the initial screening were assembled into remedial
alternatives, which were then evaluated to identify the most promising alternatives for
the site contamination.
5) Detailed analysis of the remedial alternatives retained in the previous step was
conducted.
6) Remedial alternatives retained for the detailed analysis were summarized and
compared.
7) Recommendations were made for the final alternative selection.
SUMMARY OF THE SITE CONDITIONS AND HISTORY
The SCD Site is located on Governor Lea Road near the intersection with River Road,
approximately three miles northwest of Delaware City in New Castle County, Delaware. It is
surrounded by a mixture of industrial facilities, farm land, and undeveloped properties. There
are residential and commercial properties located to the north and west within one mile of the
facility.
The SCD facility was built in 1965 on approximately 46 acres of farmland purchased from the
Diamond Alkali Company. Chlorinated benzene compounds were manufactured at the SCD
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facility from 1966 until its closure in May 2002. In addition, chlorinated nitrobenzene was
manufactured from the expansion of the SCD Facility in the early 1970s until the late 1970s. In
December of 1998, SCD was sold to Charter Oak Partners, which reorganized the company as
Metachem Products, LLC (Metachem). SCD and Metachem have been identified as PRPs.
Metachem closed the facility on May 4, 2002 and abandoned the SCD Site on May 14, 2002
after declaring bankruptcy. The EPA and the Delaware Department of Natural Resources and
Environmental Control (DNREC) have been cooperating since then to implement emergency
cleanup and remedial actions while developing an approach for the long-term rehabilitation of
the SCD Site.
Following the 1981 release of approximately 5,000 gallons of chlorobenzene during tank car
loading activities, the EPA conducted an initial site inspection and a Preliminary Assessment of
the SCD Site. The results of these investigations were used to assemble a Hazard Ranking
System (HRS) package that resulted in addition of SCD Site to the National Priorities List
(NPL) on July 22, 1987. Prior to the site's addition to the NPL, a 1986 tank collapse, and
resulting damage to surrounding tanks, released approximately 569,000 gallons of
dichlorobenzenes and trichlorobenzenes. This release impacted portions of the facility as well
as the underlying groundwater, drainage pathways, the surrounding wetlands, and Red Lion
Creek. The initial Remedial Investigation (RI) and FS, conducted by SCD to address the spill
pathways, groundwater, and off-site contamination, were completed in 1992 and 1993,
respectively.
A Record of Decision (ROD) for the SCD Site groundwater and spill pathway soils and
sediments was completed on March 9, 1995. An Administrative Order for remedial design
(RD) and remedial action (RA) was signed on May 30, 1996. To reduce/eliminate the flow of
groundwater contamination to Red Lion Creek, EPA constructed the Interim Groundwater
Remedy (IGR) in 2006/2007. The IGR includes a subsurface containment barrier (installed to
an average depth of 70 feet around the majority of the upland portion of the SCD Site) and a
groundwater extraction and treatment system (GETS). The GETS is being used to lower the
groundwater elevation within the barrier and limit/prevent the spread of contamination from
the impacted Columbia Aquifer to the underlying Potomac Aquifer.
Other releases, site investigations and remedial responses known to have occurred at the SCD
site include:
• Releases from Catch Basin 1 (discovered in 1976) and related response activities;
• 1999 Initial PRP Remedial Design Sampling conducted by SCD; and
• 2002-2004 Remedial Design and Remedial Investigation Activities including human
health and ecological Baseline Risk Assessment for the site.
Of the approximately 65 acres that make up the SCD Site, approximately 25 acres are
surrounded by a fence and form the footprint of the former SCD/Metachem manufacturing
facility (facility). The facility area is strewn with a great deal of concrete and other debris
including remnants of containment structures and portions of the former facility's wastewater
treatment plant (WWTP). The land between the former facility and the Red Lion Creek
remains undeveloped with the exception of gravel roads (single lane), a sedimentation basin,
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the temporary soil storage area (TSSA), IGR components, and other features constructed as
part of past remedial and monitoring activities. This area was wooded until the construction of
the containment barrier, when the area was bulldozed by the subcontractor who constructed the
containment barrier. Consequently, only the area outside the the containment barrier and a
small area around the waste sedimentation basin remain wooded.
OPERABLE UNIT 3 DESCRIPTION
Operable Unit 3, as covered by this FS, includes the vadose zone soil and soil gas in the
following areas:
• On Facility area including the portion of the site within the former facility fence line.
• Northern Area located between the former facility's northern fence line and the
southern side of the sedimentation pond.
On Facility Area
The On Facility area encompasses approximately 25 acres and includes the following features
that have been identified through sampling or historical knowledge as known or suspected "hot
spots" of contamination:
• Polychlorinated biphenyl (PCB) concentration area (where off-specification product was
handled)
• Catch basin #1
• Former rail siding and loading area
• Warehouse and the area to the north of the warehouse
• 1986 tank collapse area
• Facility storm drains
• Drum cleaning area
• Northern end of eastern drainage ditch
• Northeast tank farm
• Former WWTP
• Process area
Northern Area
Most of the sampling conducted outside of the facility fence line included areas not addressed
by this FS. Therefore, there are limited data available to characterize the nature and extent of
contamination found in the Northern Area. Drum remnants and solidified puddles of
chlorobenzenes were found near the northern border of the On Facility area during
construction of the Western Stormwater Basin. Because the contamination related to these
discoveries was not delineated during these construction activities, there is a concern that this
apparent dumping area might extend northward beyond the former facility fence line.
During the 2004 RI, soil was sampled from multiple depths at three locations within the
Northern Area. Six chlorobenzene compounds were detected at relatively low concentrations
(total concentration of 2.06 mg/kg) in a surface sample collected from one of the three
locations (NESB-28) in this area. Benzene was detected (at concentrations of 140 /tg/kg and
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33 /tg/kg) in two samples collected from depths of 50 ft or more below ground surface (bgs).
No other contaminants of concern (COCs) were detected in any samples collected from these
locations. No dioxin or active soil gas samples were collected from this area. Passive soil gas
samplers that were deployed in this area exhibited no or relatively low levels of contaminants.
REMEDIAL ACTION OBJECTIVES AND ARARs
The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)
requires that selected remedial actions attain a degree of cleanup that ensures the protection of
human health and the environment. Selected remedies must also comply with the substantive
requirements of all applicable or relevant and appropriate requirements (ARARs). The
following Remedial Action Objectives (RAOs) for the soil and soil gas at the SCD site are
generic goals that have been developed to achieve protection of human health and the
environment:
RAOs for Human Health;
• Prevent exposure to non-carcinogens in the soil and soil gas at concentrations that
would result in a target organ HI greater than 1 via the potential exposure routes of
inhalation, ingestion and dermal contact.
• Prevent exposure to carcinogens at concentrations that would result in a cumulative
cancer risk in excess of IxlO"5 (1E-05) via the potential exposure routes of inhalation,
ingestion, and dermal contact.
RAOs for Environmental Protection;
• Prevent risks to ecological communities exposed directly to the soil COCs and
indirectly via bioaccumulation of soil COCs in plants and earthworms.
RAOs for Limiting Further Migration of Contaminants;
• Minimize the further spread of contamination via any of the following major migration
pathways:
0 Soil to groundwater
0 Soil to surface water
0 Soil to sediment
0 Soil to air.
To ensure that the selected remedy would also meet the requirements of federal and state
regulations and guidance, a comprehensive review of these documents was performed to
identify ARARs for OU-3. These ARARs were used in the development of the Preliminary
Remedial Goals (PRGs) and in the development and screening of potential remedial
alternatives for OU-3.
PRELIMINARY REMEDIAL GOALS
PRGs protective of both human health and environment were developed for all COCs in the
soil and soil gas (those chemicals that were determined to pose unacceptable human health or
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ecological risks in the BLRA). Separate PRGs were calculated for the On Facility area and the
area outside the facility fence line. The lowest of the ecological and human health risk PRGs
was retained as the final PRO for each COC in each medium in each area.
PRGs based on human health risk were calculated for each medium of concern and COC
identified in the BLRA and RI. The site receptors considered were trespasser/visitor,
residential, industrial worker, and construction worker. Media were combined for a total
target risk when one receptor would be exposed to both media (soil and soil gas). For
carcinogens, PRGs were calculated for two target cancer risks. The first target cancer risk
was 10~6 for each COC. The second target risk was developed to result in a total cancer risk of
10~5 across all COCs and all media. For this calculation, the target risk for each COC was
determined by dividing 10~5 by the number of carcinogenic COCs within each medium. The
10~5 target total risk was used as a maximum allowable total risk level in accordance with the
DRGHSC.
For non-carcinogens, the target hazard index (HI) of 1 was divided by the number of chemicals
in soil and soil gas that affected the same target organ to determine the target hazard quotient
(HQ) for the individual COCs.
Once the target risks and HQs were calculated for the COCs, PRGs were derived from the
exposure point concentrations (EPCs) for each chemical and corresponding site risks presented
in the BLRA by solving the following equation for the PRG:
EPCI (Site Risk or HQ) = PRG I (Target Risk or HQ)
The PRG calculated using the carcinogenic 10~6 risk level was compared to the PRG for an HI
of 1, and the lower of these two PRGs was selected as the minimum end of the PRG range for
that chemical, medium, and receptor. Similarly, the PRG calculated using the carcinogenic
10~5 risk level was compared to the PRG at the HI of 1, and the lower of the two became the
maximum end of the PRG range for that chemical, medium, and receptor.
To develop PRGs for ecological risk, the risks and routes of exposure outlined in the BLRA
were used as a starting point. For OU-3, the only pertinent receptors are terrestrial receptors
because this OU does not include any aquatic habitat. To develop ecological PRGs for surface
soil that are protective of terrestrial receptors the following assessment endpoints (AEs) and
measurement endpoints (MEs) from the BLRA were considered.
• AES - Protection of nutrient cycling and terrestrial invertebrates
• AE4 - Protection of herbivorous wildlife
• AE6 - Protection of terrestrial vermivorous wildlife
• ME3.1 - Compare surface soil concentrations to those known to adversely affect
nutrient cycling and terrestrial invertebrates
• ME4.1 - Estimate food chain exposure for terrestrial herbivores and compare to no
observed adverse effects level (NOAEL) and lowest observed adverse effects level
(LOAEL) toxicity reference values
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• ME6.1 - Estimate food chain exposure for terrestrial vermivores and compare to
toxicity reference values (NOAELs and LOAELs).
To evaluate potential effects to nutrient cycling and terrestrial invertebrates, maximum detected
concentrations of the chemicals identified in the BLRA as posing a potential risk were
compared to the Ecological Soil Screening Level (Eco-SSL) for terrestrial invertebrates, the
Eco-SSL for plants, the Oak Ridge National Laboratory (ORNL) benchmark value for
earthworms, the ORNL benchmark value for soil microorganisms/microbial processes, and the
ORNL benchmark value for plants. No quantitative evaluations were performed, and no PRGs
developed, for benzene, DDD, DDE, DDT, 2-methylphenol, and thallium due to the lack of
benchmark values.
For terrestrial herbivores and vermivores, the food chain model, toxicity reference values
(TRVs), and biotransfer factors (BTFs) presented in the BLRA were used to calculate the soil
concentration that would result in an HQ of 1 for the NOAEL and LOAEL. The NOAELs
were then selected as the PRGs for these receptors.
These analyses were based primarily on OU-3 soil and soil gas data and information presented
in the August 2007 RI Report, 2003 Soil/Sediment Design Comparison Study, and the August
2007 Baseline Risk Assessment (BLRA) Report. It should be noted that PRGs for the Northern
Area were developed using Off Facility data from the RI. While these Off Facility data
include samples from the Northern Area, additional samples from other portions of the site
also are included. It is expected that these PRGs will be protective of human health and the
environment in the Northern Area. However, if delineation sampling conducted in the
Northern Area as part of an RD for the site indicates otherwise, these PRGs will need to be
revisited.
SOIL VOLUME CALCULATION
To determine the volume of soil requiring remediation, concentrations of COCs in soil and soil
gas samples in the RI Report (Black & Veatch, 2007) were compared to the corresponding
PRGs developed as part of this FS. Locations where COCs were detected at concentrations in
excess of the PRGs were included in the area requiring remediation.
In determining the volumes of soil requiring remediation to address soil risks, data from
samples collected from the top 12 feet bgs (the maximum depth to which construction activities
would be expected to proceed) were compared to the human-health related PRGs. Data from
samples collected in the 0 to 2 ft bgs depth interval were compared to ecologically driven
PRGs and human-health related PRGs. For purposes of the soil volume calculation only, the
vertical depth of the soil contamination in excess of PRGs was therefore limited to 12 feet bgs
for human health driven PRGs and 2 ft bgs for ecologically driven PRGs. Locations with
samples where contamination levels exceeded the respective PRGs were assumed to require
remediation to the relevant depth to address soil-related risks. In instances where only surface
soil samples were available and the data from those samples exceeded at least one human-
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health PRO, the full 12 ft depth of soil was conservatively assumed to require remediation to
address soil risks. Using this approach it was determined that any remedy would need to
address the entire portion of the facility area that lies within the containment barrier (22.8
acres) to depths of between 2 and 12 ft bgs. This equates to 351,060 cubic yards of site soils.
When determining soil volumes contributing to soil gas risks, all soils associated with each of
the "hot spots" (with the exception of the warehouse) were assumed to require remediation to a
total vadose zone depth of 50 ft. Approximately half of the soils underlying the warehouse and
its surrounding area were assumed to be contaminated. This approach yielded a soil volume of
464,650 cubic yards. When combined with the volume of soil requiring remediation to address
soil risk, a total remedial soil volume of 815,710 cubic yards is expected for the On Facility
area.
Using a worst case scenario for risks from soil in the Northern Area portion of OU-3, it is
estimated that an additional 1.4 acres of soils (beyond those found within the former facility
fence line) will need to be addressed to a depth of 12 ft. Inclusion of the Northern Area thus
adds 26,700 cubic yards to the volume requiring remediation for soil risks. Similarly, a worst
case scenario wherein all of the soils in the 1.4-acre Northern Area portion of OU-3 would
need to be remediated to address risks from soil gas yields a total of 111,000 cubic yards of
soil from the area that would require treatment. Based on the available soil data and passive
soil gas sampler data from the Northern Area, it is unlikely that such worst case scenarios
would be observed. For this reason, the volumes related to remedial measures necessary to
address soil and soil gas risks from the Northern Area portion of OU-3 have been broken out
separately.
To develop an estimate of the volume of soil that might require additional treatment or special
handling because of dioxin contamination in excess of the PRO, the area of each "hot spot"
was multiplied by a depth of 12 ft. This approach was selected because of the overlap between
the "hot spot" areas and dioxin samples with results greater than the dioxin PRO.
TECHNOLOGY PROCESS SCREENING AND DEVELOPMENT OF ALTERNATIVES
Technology Process Options (TPOs) representing a range of technology types with the
potential to address at least some portion of OU-3 contamination were identified. These TPOs
were then screened based on their ability to treat OU-3 wastes, feasibility for implementation,
and relative costs of implementation.
Those TPOs that were retained were assembled into remedial alternatives that could potentially
meet the RAOs for the site. The assembled alternatives were screened qualitatively based on
their effectiveness, implementability, and cost. Alternatives that were retained after the
screening underwent a detailed evaluation based on the following seven criteria specified in the
RI/FS Guidance and consistent with the NCP:
1) Overall protection of human health and the environment
2) Compliance with ARARs
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3) Long-term effectiveness and permanence
4) Reduction of toxicity, mobility or volume
5) Short-term effectiveness
6) Implementability
7) Cost
The four alternatives selected for the detailed evaluation are:
Alternative 1A; No Action-The no action alternative is included as a baseline in the
comparison of other alternatives, as required by the NCP. No remedial activities or
institutional controls would be implemented under this alternative, although some level of
natural attenuation might occur.
Alternative 2A; Surface Cap-This alternative includes construction of a concrete, asphalt, or
multilayer surface cap (such as RCRA Subtitle C cap) over 22.8 acres of the On Facility area.
The cap would be tied into the previously constructed vertical groundwater containment barrier
on the west, south, and east sides of the On Facility Area. On the north side, the cap border
will be the southern boundary of the Northern Area. If it is determined that some or all of the
Northern Area is contaminated at levels greater than the off facility PRGs, the northern end of
the cap will be extended to incorporate those areas. Alternative 2A would also incorporate
Institutional Controls (ICs) to restrict land use to commercial, light industrial, or parkland use,
prevent groundwater use, and require that any construction activities minimize the impact on
and repair any damage to the cap. These ICs could be implemented through, for example,
zoning ordinances, restrictive covenants and access agreements, in combination with air
monitoring program and continued use and maintenance of the existing site fence and warning
signs to restrict unauthorized access to the Site. Additional site preparation would be required
for cap construction because of the remaining subsurface and surface structures and debris
located in the On Facility area. Care must be taken during construction activities to avoid
damaging the previously installed containment barrier and other IGR components (including
piezometers, monitoring wells, and extraction wells). Compliance with air emissions limits and
with stormwater and sediment controls would be required.
Alternative 2B; Surface Cap with Soil Vapor Extraction (SVE)-In this alternative, the
surface cap and ICs in Alternative 2A would be supplemented with an in-situ SVE system.
SVE wells would be placed at some or all of the identified "hot spots" and operated to treat
VOCs under the cap until no significant VOC removal is being achieved. It is expected that
the SVE system would consist of several hundred air extraction and inlet wells installed to
depths of approximately 50 feet bgs. Off-gas from the SVE system would likely need to be
treated before it is discharged to the atmosphere, most likely with a vapor phase activated
carbon adsorption system. Therefore the extraction wells would be manifolded to conveyance
piping running to the off-gas treatment system. To preserve surface cap integrity, the wells
would likely be installed before the cap is constructed with conveyance piping being laid in
trenches installed in the ground surface that would then be capped. Spent carbon would be
regenerated (either on site or off site) for reuse or disposed of off site. More extensive
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sampling would likely be performed to further delineate the contaminated areas requiring
treatment. Pilot studies would be required before this alternative could be effectively
implemented.
Alternative 2C; Surface Cap with In Situ Thermal Desorption (ISTD)-Alternative 2C
includes many of the elements of Alternative 2B (ICs, surface cap, including further sampling,
pilot studies and vapor treatment). The main difference for Alternative 2C is that the "hot
spot" soil areas more than 10 feet away from the soil bentonite containment barrier would be
heated to facilitate volatilization and removal of SVOCs, PCBs, and dioxins. The "hot spot"
areas within 10 feet from the containment barriers would be treated with un-enhanced SVE.
Based on discussions with ISTD vendors, it is estimated that approximately 2,800 ISTD
heaters and 1,400 heated vapor extraction wells would be placed between 8 and 12 ft apart
over the 330,000 square feet area that comprises the "hot spots" in the site. In the event that
the Northern Area is determined to be a "hot spot" in need of treatment in addition to capping,
approximately 500 additional heaters and 250 additional heated extraction wells would be
installed to address the 60,000 square feet area. The heaters and extraction wells would extend
through the 50 ft vadose zone and would heat the soil to temperatures close to or above the
boiling points of the soil contaminants. Soil heating for ISTD can be achieved by several
methods, including hot air or steam injection, radio-frequency heating, electrical resistance
heating, and thermal conduction heating. Because temperatures in excess of 570 to 650°F
would likely be required to facilitate volatilization of most of the SCO site organic compounds
it is unlikely that hot air or steam injection approaches would be used. The volatilized
organics would then be extracted through the heated extraction wells described above. Because
of the number of wells, the potential impacts of heating on cap materials, the high costs of
materials required to construct heat resistant wells, and the amount of wiring required for the
system, ISTD treatment would likely be performed prior to the installation of the surface cap.
The ISTD wells would then be removed or abandoned to ease cap construction activities.
EVALUATION OF ALTERNATIVES
The major findings of the detailed evaluation of the four alternatives based on the seven
evaluation criteria are summarized below:
Overall Protection of Human Health and the Environment
Alternatives 2A, 2B, and 2C would all reduce human health and ecological risks from soil and
soil gas to the target levels developed in this FS Report by containing, and preventing contact
with, contamination through the use of a surface cap. Alternative 2C would improve on the
level of human health protection (specifically the health of future construction workers or
others performing intrusive site work) afforded by the surface cap by removing almost all
organic contamination from vadose zone soils in the "hot spot" areas. Alternative 2B would
also provide some measure of added protection, but would only remove VOCs and some
SVOCs from vadose zone "hot spot" soils. Alternative 1A (No Action) would not provide
protection of the environment or human health.
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Compliance with ARARs
While Alternative 1A (no action) would not meet the ARARs, Alternatives 2A, 2B, and 2C can
all be designed and implemented to comply with the identified ARARs with the exception of
the requirement to construct a liner system beneath the waste. The requirement to construct a
liner system will not be met. Instead, any cap will be tied into the soil bentonite containment
barrier that was installed as part of the IGR. This barrier is keyed into a low permeability layer
that lies between the contaminated soils of the Columbia Formation and the underlying
drinking water aquifer (the Potomac). This method of construction will isolate any
contaminated OU-3 soils left under the cap from surrounding uncontaminated areas. As a
result, the capping alternative will attain a standard of performance that is equivalent to the
standard that would be attained through the construction of a liner system. As a result, this
ARAR is waived pursuant to 40 CFR Section 300.430 (f)(l)(ii)(C)(4).
Long-term Effectiveness and Permanence
Alternative 1A (No Action) will not reduce the risks from, or the potential migration of, site
contaminants. As a result, Alternative 1A will not be effective over the long term.
Alternative 2A would provide effective containment of all contaminants located in the soil and
soil gas of OU-3. This would substantially reduce the risks related to, and the potential spread
of, site contaminants. To remain effective over the long term, maintenance activities,
including management of vegetation and burrowing animals and repairs of crack and erosional
features, would be required into perpetuity.
Alternatives 2B (SVE plus surface cap) and 2C (ISTD plus surface cap) would improve on the
effectiveness of Alternative 2A by reducing or eliminating organic contaminants in the vadose
zone of the previously identified "hot spot" areas. Because SVE would only address VOCs
and ISTD would reduce or eliminate all of the organic contaminants in vadose zone soils in
these areas, Alternative 2C would be the most effective over the long term.
Reduction of Toxicity, Mobility or Volume
Alternative 1A (No Action) would not reduce the toxicity, mobility or volume of OU-3
contaminants.
Alternatives 2A, 2B, and 2C will all reduce the mobility of the contaminants through the use of
a surface cap to reduce infiltration (reducing the soil to groundwater pathway), eliminate
contact of contaminated materials with stormwater (eliminating the soil to sediment pathway),
and containing soil gas (eliminating the soil to air pathway). Alternatives 2B and 2C also
include treatment technologies (SVE and ISTD, respectively) that would reduce the volume
and toxicity of OU-3 contaminants. The greatest reduction of contaminant toxicity and volume
is expected from Alternative 2C (combination of the surface cap and ISTD), as it would
remove VOCs, SVOCs, PCBs, and dioxins from vadose zone soils in the "hot spot" areas.
Alternative 2B (surface cap with SVE) would remove VOCs and some SVOCs from the "hot
spot" areas but would not address dioxins, pesticides, and other less volatile contaminants.
Until pilot-scale studies can be performed for the SVE and ISTD technologies, no accurate
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quantitative measure of potential contaminant reduction can be made for Alternatives 2B or
2C. Alternative 2A (surface cap alone) would not reduce the toxicity or volume of the OU-3
contaminants.
Short-Term Effectiveness
Alternative 1A (no action) would have the highest short-term effectiveness (lowest short-term
risk). Although risks from the current site conditions would continue, no disturbance of OU-3
soils (and therefore soil contaminants) would occur.
Short-term risks to construction workers, surrounding communities and the environment are
expected to occur from the implementation of Alternatives 2A, 2B, and 2C. These risks
include exposure to dust and vapor during cap construction activities, as well as continued risks
from the current site conditions before the alternatives are fully implemented. Alternatives 2B
and 2C would be somewhat less effective than Alternative 2A in the short term because of the
increased site activities (well construction, trenching, wiring and piping installation) required
to construct the SVE and ISTD systems. Additionally, the SVE and ISTD systems would
increase the mobility of organic contaminants over the short term. Short term risks associated
with Alternatives 2A, 2B, and 2C can be managed by a combination of institutional controls,
Personal Protective Equipment (PPE), and vapor and dust suppression measures to be
employed during construction activities. Vapor capture and treatment systems would address
any increase in the off-gassing of contaminants under Alternatives 2A, 2B, and 2C.
Implementability
Alternative 1A requires no action and is therefore the most easily implemented.
Of the remaining alternatives, construction of a surface cap by itself would be most easily
implemented. Although the potable water line to the treatment building would be rerouted so it
does not pass under the cap, this could be accomplished using standard construction
equipment, materials, and methods. Care would also have to be taken to avoid damage to the
existing GETS, piezometers, and monitoring wells, but the overall cap construction could
similarly be performed using standard construction equipment and methods. Additionally, no
further delineation (aside from possibly in the Northern Area) or pilot studies would be needed
before construction of a surface cap covering all of OU-3. Activities to maintain the surface
cap would be similar under Alternatives 2A, 2B, and 2C.
The proposed treatment technologies (SVE and ISTD) would require additional
characterization sampling to further delineate the "hot spot areas" and the Northern Area as
well as pilot studies to optimize well placement, blower and pipe sizing, and, in the case of
ISTD, the temperatures that will be required to achieve treatment of the OU-3 contaminants.
The time required to construct Alternatives 2B and 2C would also be greater than that needed
to complete the surface cap alone. The SVE and ISTD systems would also require controls to
limit the off-gas discharge into the air and would have to meet the substantive provisions of air
discharge permit requirements. These systems would also require the installation of several
hundred wells (in the case of SVE) to over 4,000 wells (in the case of ISTD), whereas
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Alternative 2A would require installation only of a small number of monitoring wells.
Alternative 2A might also require a vapor treatment system to meet the substantive provisions
of air discharge permit requirements off-gas from the cap soil gas capture system. While SVE
could be implemented using the utilities already available on site, it is possible that a higher
voltage electrical supply and a natural gas supply will need to be routed to the site if ISTD is
selected as part of the site remedy.
Cost
Alternative 1 requires no action and therefore has no associated project costs. The order-of-
magnitude level estimates for total project costs (shown as present value estimates taken over
30 years at a discount rate of 5%) for the remaining alternatives are as follows:
Alternative 2A (Surface Cap)
Alternative 2B (Surface Cap + SVE)
Alternative 2C (Surface Cap + ISTD)
$18.5
$26.2
$99.8
$17.5
$25.2
$98.8
$11.5
$19.1
$92.8
NOTE: Because of the lack of definitive data showing that levels of contamination in the Northern Area
portion of OU-3 require remediation, the costs associated with the Northern Area are not
included in the above estimates. If additional sampling shows that risks from soil and/or soil
gas will require remediation, additional costs (up to a maximum of between $421,000 and
$861,000 to cap the entire 1.4 acre Northern Area) would be incurred.
Alternative 2A is the least expensive of these alternatives, followed by Alternative 2B and
Alternative 2C. For all containment alternatives, asphalt would be the least expensive capping
material choice, followed by concrete and multilayer soil.
PREFERRED ALTERNATIVE
Based on evaluation of the four retained alternatives using the seven evaluation criteria, it
appears that Alternative 2A (Surface Cap) would be the overall best approach for addressing
the risks from the soil and soil gas contamination that is present in OU-3. This alternative
would be consistent with the identified ARARs and would provide protection of human health
and the environment over the long term by eliminating the soil and sediment exposure
pathways and substantially reducing the soil gas exposure pathway. ICs would be used to
restrict land use, prevent the use of site groundwater, require the inclusion of vapor intrusion
protection in future building construction, ensure that remedial measures remain in good
functional condition, and require that any construction activities minimize the impact on and
repair any damage to the cap, and keep the public informed of site developments and hazards.
These controls could be implemented through zoning ordinances, access agreements, restrictive
covenants, and public awareness efforts. These ICs would be required to increase the level of
protection and ensure that the surface cap continues to be effective over the long term.
Alternatives 2B and 2C would offer some increased protection of human health during future
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intrusive activities (e.g., construction, well installation, and cap repair) by reducing
contaminant levels in "hot spot" soils and soil gas, but any increased risk associated with
Alternative 2A could be managed through the use of personal protective equipment (PPE),
vapor and dust suppression, worker training and other precautions.
Although installation of a surface cap would not reduce the toxicity or volume of the OU-3
contaminants, it would reduce the mobility of the contaminants by reducing/eliminating
precipitation infiltration, preventing stormwater contact with contaminated soils, preventing the
airborne transport of contaminated soil particles, and minimizing the potential off-gassing of
soil gases. While each of the containment alternatives could be readily constructed,
implementation of Alternative 2A would be the easiest of the three and could be accomplished
in the shortest period of time for the lowest overall cost.
Although asphalt would be the least expensive option and would provide protection that should
be (if properly maintained) equal to that offered by the concrete and multilayer soil options, a
choice must be made as to the possible future uses of the capped area and the importance of
site appearance. While the concrete and asphalt caps would be preferable if redevelopment of
the site for some low occupancy business purpose is envisioned, a multilayer soil cap would
likely be more visually appealing and more amenable to conversion of the land to park space or
naturalized open space.
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FEASIBILITY STUDY REPORT
STANDARD CHLORINE OF DELAWARE SITE
OPERABLE UNIT 3 (OU-3)
NEW CASTLE COUNTY, DELAWARE
1.0 INTRODUCTION
This Feasibility Study (FS) Report has been developed for Operable Unit 3 (OU-3) of the
Standard Chlorine of Delaware (SCD) Site (Figure 1.1). This FS Report has been prepared by
HydroGeoLogic, Inc. (HGL) under Contract Number EP-S3-07-05 with Region 3 of the U.S.
Environmental Protection Agency (EPA), in accordance with Task 12 of Work Assignment
002RICO03H6.
1.1 PURPOSE AND ORGANIZATION OF THE REPORT
The purpose of this FS Report is to develop and evaluate remedial alternatives that may be
feasible for addressing potential risks to the human health and the environment posed by
contaminated soils and soil gas at the SCD site. The scope of this FS is based on discussions
with the EPA, information obtained during the Remedial Investigation (RI), and the results of
the baseline risk assessment (BLRA).
This document has been prepared in accordance with the requirements of the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP), 40 CFR Part 300, regulations for
implementing the Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA), as well as the guidance provided by the EPA in the Guidance for Conducting
Remedial Investigations and Feasibility Studies Under CERCLA (EPA, 1988). The FS Report
is organized as follows:
• The subsequent subsections of Section 1 summarize site history and setting, as well as
current site characteristics. These topics are discussed in more detail in the August 2007
RI Report (Black and Veatch, 2007a).
• Section 2 discusses remedial action objectives, including identification of applicable or
relevant and appropriate requirements (ARARs) for contaminants of concern (COCs) in
soil and soil gas at the site and for potential remedial actions. Site-specific Preliminary
Remedial Goals (PRGs) are developed, and the areas and volumes of soil requiring
remediation are estimated.
• In Section 3, technologies with the potential to remediate soil and soil gas at the site are
identified and screened.
• In Section 4, the technologies retained after the initial screening in Section 3 are
assembled into remedial alternatives, which are then evaluated to identify the most
promising alternatives for the site contamination.
• Section 5 provides a detailed analysis of the remedial alternatives retained in Section 4.
• In Section 6, remedial alternatives retained for the detailed analysis are summarized and
compared.
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1.2 SITE BACKGROUND
Background information on the SCD site is summarized below. Additional background
material can be found in the August 2007 RI Report prepared by Black & Veatch (Black &
Veatch, 2007a).
OU-3 encompasses the following areas and media:
• Area within the former facility fence line: soil and soil gas.
• Area to the north of the former facility fence line: soil and soil gas between the former
facility's northern fence line and south of the sedimentation pond.
Pertinent site features are shown on Figure 1.2, and OU-3 is highlighted on Figure 1.3. For
the purposes of this FS, OU-3 is subdivided into the On Facility Area and the Northern Area.
The On Facility area encompasses those portions of the site that lie within the former facility
fence line. The Northern Area consists of the area between the northern leg of the facility
fence line and the southern edge of the waste sedimentation pond. Groundwater, surface
water, sediment, and soils from other areas located beyond the facility fence line are addressed
under other operable units. Columbia Aquifer groundwater (OU-1) is being addressed by the
Interim Groundwater Remedy (IGR) which was constructed in 2006 and 2007 and includes a
groundwater containment barrier and a groundwater extraction and treatment system (GETS).
Off facility soils and sediments along the 1986 spill pathways will be covered under OU-2, and
OU-4 will cover remaining off facility areas that have been impacted by site contamination.
1.2.1 Site Location and Description
The SCD Site is located on Governor Lea Road near the intersection with River Road,
approximately three miles northwest of Delaware City in New Castle County, Delaware
(Figure 1.1). The area is a mixture of industrial facilities, farm land, and undeveloped
properties, although there are residential and commercial properties located to the north and
west within one mile of the facility. Approximately 152,000 people (from residences and
businesses) obtain potable water from public and private wells within a three-mile radius of the
site (Black & Veatch, 2007a).
The SCD Site extends from Governor Lea Rd. in the south to the Red Lion Creek in the north.
Land owned by Occidental Chemical Company (formerly Diamond Shamrock and Diamond
Alkali) lies immediately to the east of the SCD Site while an Air Products, Inc. hydrogen
processing facility abuts the western fence line. Across Governor Lea Road lies property that
is the site of buildings that were previously used as offices and a change house by SCD and
Metachem. This property and these buildings are now owned by Ion Power, Inc.. Farther to
the south is a refinery that is currently owned by Valero Corporation (Valero) and was
previously owned by Motiva Enterprises, LLC, Premcor, Inc., Star Enterprises, and the
Tidewater Refining Company.
Of the approximately 65 acres that make up the SCD Site, approximately 25 acres are
surrounded by a fence and form the footprint of the former SCD/Metachem manufacturing
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facility (facility). As the result of remedial, removal, and demolition activities that have
occurred since the potentially responsible party's (PRP's) abandonment of the site, the facility
area is strewn with a great deal of concrete and other debris. This debris includes remnants of
multiple containment structures and portions of the former facility's wastewater treatment plant
(WWTP). The land between the former facility and the Red Lion Creek remains undeveloped
with the exception of gravel roads (single lane), a sedimentation basin, the temporary soil
storage area (TSSA), IGR components, and other features constructed as part of past remedial
and monitoring activities. This area was wooded until the construction of the IGR, when the
area was bulldozed by the subcontractor who constructed the containment barrier.
Consequently, only the area outside of the containment barrier and a small area around the
waste sedimentation basin remain wooded.
The facility area and the upland areas within the containment barrier alignment to the north of
the former facility are relatively flat and lack significant vegetation. Near the Red Lion Creek
and its unnamed tributary located to the west of Air Products and the undeveloped area to the
north of the facility (the unnamed tributary), the terrain slopes sharply downward to wetland
areas surrounding these two water bodies.
1.2.2 Site Operational History
The SCD facility was built in 1965 on approximately 46 acres of farmland purchased from the
Diamond Alkali Company. The following year, SCD began production of chlorinated benzene
compounds. These compounds were manufactured at the SCD facility until its closure in May
2002. SCD, and later Metachem, used chlorine piped from the Occidental Chemical facility
and benzene (obtained primarily from the refinery located south of the facility) to produce
chlorinated benzene compounds. Following another expansion in the early 1970s, SCD added
chlorinated nitrobenzene to its product line and increased production of chlorobenzene,
dichlorobenzene, and trichlorobenzene. SCD ended chlorinated nitrobenzene production in the
late 1970s, and the related capacity was switched to the production of chlorobenzene.
Following an expansion in the late 1970s, the SCD facility produced chlorobenzene,
paradichlorobenzene, various isomers of trichlorobenzene, and chlorobenzene-based insulating
fluids (Weston, 1993).
In December of 1998, SCD was sold to Charter Oak Partners which reorganized the company
as Metachem Products, LLC (Metachem). Metachem purchased all of the land located
between the facility fence line and the Red Lion Creek that was known to have been impacted
by SCO's releases. SCD and Metachem have been identified as PRPs.
On April 30, 2002, Metachem announced that the bankruptcy of one of its customers had
resulted in a decision to close the SCD facility. Metachem closed the facility on May 4, 2002
and declared bankruptcy six days later (May 10, 2002). Metachem abandoned the SCD Site on
May 14, 2002, and the EPA and the Delaware Department of Natural Resources and
Environmental Control (DNREC) have been cooperating since then to implement emergency
cleanup and remedial actions while developing an approach for the long-term rehabilitation of
the SCD Site.
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1.3 ENVIRONMENTAL SETTING
1.3.1 Site Topography and Surface Drainage
The majority of the SCD Site is generally flat and is bounded by Red Lion Creek to the north,
the unnamed tributary to the west and topographic highs to the south and east. The formerly
wooded area to the north of the former facility decreases in elevation from about 50 ft above
mean sea level (amsl) along the containment barrier alignment to near sea level at the Red Lion
Creek and its unnamed tributary. The site exhibits a north-south trending surface water divide
that traverses the approximate center of the facility and the formerly wooded area (Weston,
1993).
Surface drainage is controlled by topographic highs toward the southern end of the site and
flows in a dendritic pattern toward the dominant drainage feature of Red Lion Creek. The
surface water divide on the facility portion of the site previously directed drainage to the
eastern drainage ditch - a shallow (approximately one to four feet deep) drainage ditch that ran
through the eastern portion of the facility - and a shallower drainage ditch that ran along the
facility's western boundary. These drainage features captured and directed stormwater to two
weirs that were located in the northeastern and northwestern corners of the facility,
respectively. The weirs discharged stormwater off site under a National Pollutant Discharge
Elimination System (NPDES) permit. The western weir discharged to the Red Lion Creek via
a drainage gully that leads to the unnamed tributary, while the outflow from the eastern weir
traveled overland to the Red Lion Creek. Both weirs were removed during construction
activities associated with the IGR and replaced with stormwater/sediment basins located at the
northeast and northwest corners of the former facility. The western drainage feature was
destroyed during these construction activities and has been replaced with a swale located
approximately 30 feet inside the western leg of the containment barrier alignment. The
southern portion of the eastern drainage ditch was also filled in during demolition/construction
activities, and a separate drainage swale was installed to the east side of the asphalt road
installed as part of the IGR. The area to the east of this new swale is rutted with tire marks and
drainage is inadequate. The northern portion of the eastern drainage ditch was excavated to
remove contaminated surface soils and the section reconstructed to flow to the eastern
stormwater/sediment basin.
The IGR construction activities have resulted in a generally flatter topography that is less
conducive to the shedding of water from certain areas. In the formerly wooded area, the
relatively flat grade has resulted in substantial areas of ponding. In the facility area, the
demolition and deactivation of numerous facility storm drains (performed during emergency
removal activities and salvage operations) has resulted in areas of ponding in the southern
portion of the site.
1.3.2 Geology
Subsurface investigations conducted during and before the RI indicate the presence of the
following subsurface strata at the SCD Facility, in descending order:
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• Fill and Recent Deposits (Native Soils)-The fill consists of gray clay from dredge
spoils or orange to brown sands from local sources. The recent deposits consist of
sandy and clayey marsh deposits including peat.
• Columbia Formation (Quaternary)-As described in the CRA intermediate Remedial
Design Report (CRA, 2000), the Columbia Formation occurs in channel fillings in
northern Delaware and in broad sheets created by coalesced braided stream channels
across central Delaware. Jordan and Talley (1976) hypothesize that the Pleistocene
sediments were deposited by the discharge of large quantities of water and detritus from
southerly flowing streams originating within the glaciated area to the north of Delaware
City. Spoljaric (1967) studied the channel filling nature of the Columbia Formation in
New Castle County and recognized a major, north-south trending Pleistocene fluvial
channel system that appears to occur near the general area located north of Delaware
City. Within these channels, the Columbia Formation directly overlies the Potomac
Formation where the Merchantville Formation has been incised. The Columbia
Formation consists largely of fine sand to coarse sand with varying amounts of gravel.
It typically has distinct orange to yellow color. A basal sand and gravel layer is a key
marker bed indicating the bottom of the formation. Small lenses or stringers of silty
clay or clayey silt occur scattered throughout the formation. In the FS study area, the
thickness of the Columbia Formation ranges from 55 to 74 ft, with a general decrease
in thickness to the north.
• Merchantville Formation (Cretaceous)-In the western portions of the SCO facility,
the Columbia Formation is underlain by the marine sediments of the Merchantville
Formation and is predominantly composed of material ranging from gray to green gray
glauconitic, micaceous clay to silty/sandy clay. The Merchantville Formation has been
eroded by a north-south paleochannel in the central and eastern sections of the site. The
lowest area of the paleochannel is located in the eastern portion of the SCO Site with a
longitudinal axis that trends in a general north-south direction. In these areas, the
Merchantville Formation is absent and the Columbia Formation is underlain by the
Potomac Formation. The Merchantville Formation on-site averages 10.2 feet thick and
where present, has a maximum thickness of 22 feet (Black and Veatch, 2007a).
• Potomac Formation (Cretaceous)-The Potomac Formation underlies areas of the
Columbia and Merchantville Formations. The Potomac consists largely of variegated
red, gray, purple, yellow and white clays and silts interbedded with three relatively
thick silty sand units. The upper portion of the Potomac Formation in the FS study area
is comprised of interbeds of clay, silt, and sand. The lateral extent of these upper
clays and/or silts as well as their ability to restrict vertical groundwater flow and
contaminant migration is currently being investigated (Brayton, 2009). Lithologic data
from the northern end of the site indicates an absence of clays thus allowing a hydraulic
connection between the Columbia and Potomac sands in some areas near the Red Lion
Creek (Black & Veatch, 2005; Brayton, 2009).
1.3.3 Hydrogeology
The Columbia Aquifer is the upper-most aquifer in the region and is associated with very
productive sands and gravels of the Columbia Formation. The surface of the groundwater table
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forms the upper boundary of the Columbia Aquifer and generally occurs at depths ranging
from near ground surface (near the wetlands at Red Lion Creek) to approximately 45 feet bgs
at the upland area near the facility (Black & Veatch, 2007a). A portion of the Columbia
Aquifer underlying the SCD Site includes a part of a north-south trending paleochannel filled
with unconsolidated sand and gravel and pockets of silts and clays
The Columbia Aquifer is unconfined at the site, and groundwater flow generally mimics
topographic elevations, with flow towards Red Lion Creek, an unnamed tributary to the west
and northwest, and the marsh area surrounding the northern portion of the site. The saturated
thickness of the Columbia Aquifer at the site varies between approximately 10 and 40 feet.
The average groundwater hydraulic gradient in the Columbia Aquifer ranges from 0.003
feet/foot to 0.007 feet/foot to the north-northwest (Black & Veatch, 2007a). Although the site
water levels may slightly fluctuate due to seasonal precipitation changes, no tidal influences
were observed during the RI (Black & Veatch, 2007a).
The Columbia Aquifer hydraulic conductivity is estimated to range from 5 to 134 feet per day,
but has been observed as high as 184 to 441 feet per day (Black & Veatch, 2007a). The RI also
noted that the water level in Red Lion Creek is lower than the adjacent groundwater table in
the Columbia Aquifer (4 feet amsl) indicating that there is flow from the Columbia Aquifer
into Red Lion Creek and the unnamed tributary (Black & Veatch, 2007a).
Before the installation of the IGR containment barrier (see Section 1.4.8 of this Report), site
groundwater elevations in the Columbia ranged from approximately 16.5 feet amsl in the south
to approximately 3 feet amsl in areas adjacent to Red Lion Creek. As expected, the pumping
associated with the GETS is lowering the average groundwater elevations within the
containment area. The water levels measured in March 2009 indicate that the groundwater
elevations within the containment area ranged from approximately 10.7 to 11.7 feet amsl at the
southern end to approximately 6 to 7 feet amsl at the northern end. This compares to a
containment area groundwater elevations ranging from a maximum of 16.5 feet amsl to
minimums of 5.4 to 5.9 feet amsl in this area before the containment barrier was installed.
Localized groundwater depressions (with a minimum elevation of approximately 2.3 feet amsl)
are formed in the areas surrounding extraction wells associated with the GETS. To the north
of the containment barrier, average groundwater elevations in the wells located along the
southern edge of Red Lion Creek have dropped from 2.6 feet amsl before the containment
barrier installation to approximately 1.7 feet amsl in March 2009. This drop is most likely
caused by the reduction of groundwater flow into this area by the upgradient containment
barrier. The containment barrier diverts groundwater flow around the facility portion of the
site so that the water flows toward the east and west before resuming a more northerly route
toward Red Lion Creek.
The Merchantville Formation consists of dark gray to black micaceous clays and silty-clays.
Regionally, the Merchantville acts as a confining unit separating the Columbia and Potomac
aquifers. Based on investigations conducted as part of the RI as well as more recent
investigations discussed below, the Merchantville Formation is absent in some areas along the
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northern portion of the site. In these areas, the Columbia Aquifer is underlain by either clayey
sediments of the Potomac Formation or by silty-sand material where the upper clays have been
eroded by the paleochannels. Below these upper units, there is a sequence of interbedded clays,
silts, and sands that eventually form the Potomac Upper Hydraulic Zone (UHZ). It is believed
that within the containment area at the SCD Site, the clay/silty-clay layer associated with the
Merchantville and/or the Upper Potomac formations generally act as an aquitard to restrict
groundwater flow between the Columbia and Potomac UHZ Aquifer.
In August 2005, the U.S. Geological Survey began investigating the hydraulic connection
between the Columbia (unconfined) aquifer and the Potomac (confined) aquifers (Brayton,
2009). A pump test conducted in 1990 showed a good hydraulic connection within the upper
Potomac sands, but no apparent connection between the Columbia and Potomac aquifers
(Brayton, 2009). Three Potomac wells were installed in 2003 and 2004 with subsequent water-
quality monitoring. As of 2009, with the exception of well PW-01, contamination has not been
detected at any of these wells (Brayton, 2009). The contamination detected in PW-01 was
suspected of originating from a former waste pipeline, and concerns regarding well
construction led to eventual abandonment in May 2007.
Additional wells screened within the Potomac Aquifer were installed in 2007. Gamma logs
and vertical water-quality profiling were conducted on selected wells (Brayton, 2009). At two
of the locations, the wells were installed with a screened interval set below existing
Merchantville clay, but above Potomac clay. This thin discontinuous sand zone has been found
to be similar in water chemistry to the unconfined Columbia aquifer, and water levels have
behaved similar to Columbia wells, indicating that the Merchantville is not an effective
confining unit (Brayton, 2009). Several of the additional wells were completed in Potomac
sand, approximately 140 feet below land surface and have exhibited a similar water-level
behavior to previously installed Potomac wells. Brayton (2009) notes that wells north of Red
Lion Creek show continuous vertical hydraulic connection with no confining units present
(Merchantville or Potomac clay). Two wells placed northwest of the site, show vertical
hydraulic connection below a confining Potomac clay; both wells are screened in a continuous
sand. One of the two wells is screened in a silty sand below several thick sequences of
Potomac clay, overlain by Merchantville clay.
Although the aforementioned clay/silty-clay layer reduces groundwater flow between the
Columbia and Potomac UHZ Aquifers throughout much of the SCD Site, recent detections
(over the past two years) of site-related contaminants in one well screened in the Potomac
Aquifer as well as the observation of dense non-aqueous phase liquid (DNAPL) during the
Remedial Design Investigation at a depth of 150 feet indicate that some transmission is
occurring. The origin (and transport pathway) of this contamination and location of gaps in the
confining clay(s) are an ongoing focus of the USGS Potomac Aquifer Study.
The Potomac Aquifer is a source of potable groundwater and is capable of producing
significant quantities of quality water out of the Potomac UHZ. Based upon water-level
measurements and the distribution of VOC contamination, groundwater flow in the Potomac
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Aquifer is believed to follow an east-southeast direction in the area of the site.
There is still some debate as to whether this transmission is occurring in the northern and/or
northwestern portions of the site, is associated with releases from the former facility
wastewater discharge line (located to the east of the facility), or is related to some gaps in the
aforementioned clay layer within the containment area. Data obtained during quarterly
sampling of a number of Potomac-screened wells (conducted over the past 18 months) has not
indicated any additional contamination in the Potomac. Additional testing, including the
installation and sampling of double-cased monitoring wells screened in the Potomac, is
scheduled for the summer of 2009.
1.4 PREVIOUS SITE INVESTIGATIONS AND REMEDIAL RESPONSES
1.4.1 Introduction
During the three years following the discovery of the 1981 spill, EPA conducted an initial site
inspection and a Preliminary Assessment of the SCO Site. The results of these investigations
were then used to assemble a Hazard Ranking System (HRS) package that resulted in proposal
of the SCD Site to the National Priorities List (NPL) on September 18, 1985. The SCD Site
was formally added to the NPL on July 22, 1987. The SCD Site has been assigned CERCLIS
number DED041212473.
A Consent Order between DNREC and SCD covering the performance of a Remedial
Investigation and Feasibility Study (RI/FS) at the SCD Site was signed on January 12, 1988
and amended on November 14, 1988. The RI/FS for this Consent Order was conducted
between 1991 and 1993. A Record of Decision (ROD) for the SCD Site spill pathway was
completed by EPA on March 9, 1995, but this ROD did not cover the bulk of the
manufacturing facility which was, at the time, still operating. A Unilateral Administrative
Order for remedial design (RD) and remedial action (RA) was issued by EPA to SCD on May
30, 1996.
A design stage investigation conducted in 2002 and 2003 indicated that contamination in the
tributary wetlands located west of the site's upland portion was more widespread, particularly
with regard to depth, than was indicated in the PRP's RI Report. The RD investigation was
followed by an RI that included, among other areas, the former facility portion of the site.
The EPA also undertook bench-scale and pilot-scale tests of in situ chemical oxidation (ISCO)
as part of a focused feasibility study (FFS) to determine whether ISCO could be a more cost-
effective approach for remediating the impacted wetlands than the low temperature thermal
desorption (LTTD) approach specified in the 1995 ROD. The results of this pilot study were
presented in the Wetlands Remedial Approach and Pilot Study Summary Report for The
Standard Chlorine of Delaware Site - New Castle, Delaware (HGL, 2009).
Observations made during work performed (in early 2008) by the U.S. Geological Survey
(USGS) indicate that site related contamination is likely present in the wetlands located east of
the undeveloped upland portion of the site. These observations included strong odors from a
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groundwater seep and surrounding portions of the eastern wetlands.
The major sampling and remedial activities related to OU-3 are detailed below.
1.4.2 Catch Basin 1 Release and Related Remedial Activities
In March 1976, SCD determined that Catch Basin 1 (part of the facility's WWTP) had been
leaking into the subsurface. Catch Basin 1 was a settling basin used to recover product from
the facility's wastewater. According to the 1992 RI Report, the catch basin was repaired at
that time, but the contaminated soil surrounding the catch basin was left in place (Weston,
1993). Releases from Catch Basin 1 are believed to be the main source of the more highly
chlorinated contamination [i.e., tetrachlorobenzenes, pentachlorobenzene, hexachlorobenzene,
polychlorinated biphenyls (PCBs)] that is present in the subsurface and groundwater.
1.4.3 1981 Release and Related Remedial Activities
In September 1981, an accident that occurred during the loading of a railroad tank car resulted
in the release of approximately 5,000 gallons of chlorobenzene. This release occurred on the
rail siding that was located along the western boundary of the SCD Site. Chemicals from this
release flowed into the drainage ditch that ran north and south along the rail siding. The
spilled materials then flowed into the drainage ditch that runs in front of Air Products and
discharges into the unnamed tributary. As part of their response action, SCD collected a
portion of the spilled chemicals and removed surface soils from the spill area and the drainage
ditch located in front of Air Products. The excavated soil was disposed of at a permitted off-
site disposal facility. This removal action was performed under the supervision of DNREC.
As stated in the 1992 RI Report, SCD also conducted a limited subsurface investigation in the
area of the release to determine the potential for migration of the spilled chlorobenzene into the
underlying groundwater. Based on the results of this investigation, SCD and DNREC
concluded that the potential existed for groundwater contamination to occur (Weston, 1992).
As a follow-up to the soil clean up and sampling efforts, SCD installed groundwater
monitoring wells at various locations on the SCD property. Analysis of the samples collected
from these wells revealed that the groundwater was contaminated with multiple types of
chlorinated benzenes. Based on these analyses, it was determined that the primary source for
the more chlorinated benzene compounds in the groundwater was the aforementioned Catch
Basin 1 leak that SCD detected in March 1976 (Weston, 1992).
To address the groundwater contamination, SCD installed a series of recovery wells and
modified their existing WWTP to include an air stripper. An additional clarifier and tertiary
sand filter were added to address the increased flow. A modified NPDES permit for the
facility was issued by DNREC on January 21, 1985 and the modified system was brought on-
line in 1986. At some point following their installation, the recovery wells and associated
piping fell into disrepair (largely due to corrosion issues) and suffered repeated shut downs.
According to the EPA Emergency Removal Team (ERT), the wells were shut off permanently
on April 3, 2003 (Black & Veatch, 2005).
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1.4.4 1986 Release and Related Remedial Activities
In January 1986, a 375,000-gallon tank located near the western boundary of the SCD Site
collapsed and damaged three nearby tanks. The tank failures resulted in the release of
approximately 569,000 gallons of various volatile organic compounds (VOCs) including
paradichlorobenzene and trichlorobenzene compounds. As the spilled materials (which were
normally heated so that they would remain in a liquid state) cooled, some of the material
solidified on the ground. This allowed SCD to recover and reprocess some of the spilled
chemicals.
A portion of the spilled chemicals traveled northward to the northwest corner of the SCD
facility and flowed down a drainage gully into the wetlands surrounding the unnamed tributary.
Chemicals also flowed eastward across the SCD property and into the facility's eastern
drainage ditch. These chemicals then traveled northward to the facility's eastern weir. No
historical data pertaining to the northeastern spill pathway outside the fence line are available,
but a recent sampling event did address the eastern wetlands at the facility's stormwater
discharge point. Data from this event were not available at the time of FS preparation.
In an attempt to minimize the spread of contaminants from the western wetlands into Red Lion
Creek, SCD constructed a berm and a silt fence across the mouth of the wetlands. The silt
fence has deteriorated and is no longer functional. Contaminated sediments were also
excavated from the wetlands area to the north of the silt fence and placed in the lined
sedimentation pond that is located to the north of facility fence line. Soils that were heavily
contaminated as a result of the spill were placed in soil piles constructed northwest of the
sedimentation pond (Weston, 1992).
As part of their RI activities, the PRP collected water samples from between the two layers of
the sedimentation pond liner and found that contaminants had permeated at least the upper
layer. Based on the age of the liner system and the detected contamination, it has been
suggested that contamination has migrated from the basin into the underlying soil and
groundwater (Weston, 1992).
1.4.5 1991-1992 Remedial Investigation and Feasibility Study
The initial RI and FS conducted by SCD to address the spill pathways and off-site
contamination were completed in 1992 and 1993, respectively. The spill RI and the FS are
discussed and summarized in reports assembled by the PRP's contractor (Weston, 1992 and
1993). As part of this RI, sampling of the soil, surface water, groundwater, and sediments
located in and around the SCD site was conducted. This sampling effort concentrated on the
1981 and 1986 spill pathways and off facility areas because the SCD facility was still in
operation. Sampling activities related to chemical characterization of OU-3 soil and soil gas
are briefly discussed below. Complete details of the RI sampling effort are presented in the
1992 RI Report.
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1.4.5.1 1981 Release Pathway Sampling
Thirty-five soil samples were collected from 16 locations along the path traveled by the
chlorobenzene spilled in 1981. At each location, samples were collected from the 0 to 6 inch
and 12 to 18 inch depth intervals. Site contaminants were detected in one sample at
concentrations of 8,901 mg/kg (0 to 6 inch interval) and 311 mg/kg (12 to 18 inch interval).
The remainder of the shallow/surface soil sample results revealed COC concentrations ranging
from 0.04 mg/kg to 34.1 mg/kg. Three subsurface samples were collected [from depths of 5-
7 feet, 15-17 feet and 25-27 feet below ground surface (bgs)] from the location where elevated
contaminant concentrations were detected. Analysis of subsurface samples showed COC
concentrations ranging from 3,049 mg/kg to 8,324 mg/kg.
Testing conducted on two samples (one shallow/surface soil sample and one subsurface soil
sample) from this area did not indicate the presence of polychlorinated biphenyls (PCBs)
(Weston, 1992).
1.4.5.2 1986 Release Pathway Sampling
Eighty soil samples were collected from 29 locations along the 1986 spill's northern flow path
(including the rail siding and western drainage gully) and the eastern flow path (including the
eastern drainage ditch and along the eastern fence line). Surface soil and shallow subsurface
soil samples were collected from 0 to 6 inches bgs and 12 to 18 inches bgs at all but one
location. A total of 25 deeper subsurface soil samples were collected from two locations in
the rail siding area, two locations in the western drainage gully, and three locations in the
eastern drainage ditch. Contamination was widespread in these samples with the shallower
samples generally more contaminated then those from deeper intervals. No PCB data are
available for any of these samples.
Northern Flow Path-A median COC concentration of 2,883 mg/kg was observed in surface
and shallow subsurface samples collected from along the northern portion of the facility's rail
siding. COC concentrations in deeper subsurface samples collected from this area were
generally lower (ranging from 0.43 mg/kg to 837 mg/kg).
Significant contamination was also found in samples collected from the western drainage gully.
In surface and shallow subsurface soil samples collected from the western drainage gully, COC
concentrations ranged from 3.5 mg/kg to 103,525 mg/kg with a median concentration of 4,402
mg/kg. COC concentrations found in the deeper subsurface soil samples were lower (median
concentration of 1,302 mg/kg) than those found in samples from the shallower intervals.
Eastern Flow Path-Most of the surface and shallow subsurface samples collected from the
eastern drainage ditch had elevated concentrations of COCs with concentrations ranging from
1.3 mg/kg to 42,179 mg/kg (median of 2,250 mg/kg). In contrast, only four of the 15
subsurface samples collected from the drainage ditch area had COC concentrations greater than
100 mg/kg. None of the 10 samples collected along the eastern facility fence line had
substantially elevated COC concentrations (Weston, 1992).
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1.4.5.3 Catch Basin Number 1
Fourteen subsurface samples were collected at depths ranging from 3 feet bgs to 32 feet bgs
from a total of four locations surrounding Catch Basin 1. The median COC concentration in
these samples was 3,185 mg/kg with individual sample concentrations ranging from 10.5
mg/kg to 24,699 mg/kg (Weston, 1992).
1.4.6 1999 Initial PRP Remedial Design Sampling
To fulfill a condition specified in the 1995 ROD, the PRP performed "hot spot" sampling
during which 17 surface soil samples were collected from areas with a high potential for
elevated levels of contamination. Total COC concentrations in these samples ranged from 4
mg/kg to 210 mg/kg with a median result of 27 mg/kg.
The PRP also collected 15 samples from soil borings installed to the north of the facility fence
line. Five more subsurface soil samples were collected as part of monitoring well installation
activities along the southern and northern edges of the Red Lion Creek, and one subsurface soil
sample was collected during installation of a monitoring well on the Air Products property
located west of the facility fence line. COCs were detected in all of these samples with a
maximum detected concentration of 40.56 mg/kg (Conestoga Rovers and Associates, 2000).
1.4.7 2002-2004 Remedial Design and Remedial Investigation Activities
The field activities conducted during the 2002 - 2003 RD and the 2004 RI/FS field
investigation are described in the 2007 Final RI Report (Black & Veatch, 2007a) and
summarized below. The RD investigation efforts occurred from October 2002 through May
2003 and focused largely on the spill pathways associated with major documented releases that
occurred at the site and the surrounding wetlands. The RD sampling activities included
sampling of soil, sediment and surface water.
The facility-wide RI field sampling activities occurred from June to December 2004 and
focused primarily on characterizing the horizontal and vertical nature and extent of
contamination, evaluating risks from the site to human health and the environment, and
providing data to assist with remedy selection. Groundwater, surface and subsurface soil, soil
gas, sediment, and surface water were sampled during the RI. The risk assessment evaluation
focused on the following areas (presented in Figure 1.2), which were known or suspected to
have maximum concentrations of contamination at the site:
• PCB concentration area (where off-specification product was handled);
• Catch Basin #1;
• Rail Siding;
• Warehouse;
• Drum cleaning area;
• Northern end of eastern drainage ditch;
• Loading area;
• WWTP;
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• Process Area;
• Western drainage gully; and
• Air Products drainage ditch.
The RI field investigation also included limited sample collection in the following off-site areas
to determine the potential impacts from the site:
• Wooded area to the north of the facility;
• Drainage pathways to the east and northeast of the facility;
• Suspect barren area to the northeast of the SCD facility;
• Sediment and surface water in Red Lion Creek and its unnamed tributary; and
• Groundwater in the Columbia and Potomac aquifers.
A Baseline Risk Assessment (BLRA) was performed based on the data collected in the RI. The
conclusions of the BLRA are further discussed in Section 1.6 of this FS Report. Soil and soil
gas sampling activities in the areas covered by this FS are discussed in more detail below. Soil
and soil gas data collected during the RD and RI activities and described in the RI Report
(Black and Veatch, 2007a) served as the basis for the analysis in this FS Report.
1.4.7.1 Surface Soil Sampling
Approximately 100 surface soil samples (including duplicates) were collected during the RD
and RI investigations. Of these, 53 samples (including duplicates) were collected from On
Facility areas and Off Facility areas covered by this FS Report. Surface soil sampling
locations are presented on Figure 1.4. The samples were analyzed for all or some of the
following target constituents: Target Compound List (TCL) VOCs and semivolatile organic
compounds (SVOCs), TCL pesticides/PCBs, Target Analyte List (TAL) inorganics (including
cyanide), dioxin/furans, total organic carbon (TOC), specific gravity, percent moisture
content, as well as the following flex clause constituents: 1,2,3-trichlorobenzene, 1,3,5-
trichlorobenzene, 1,2,3,4-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, and
pentachlorobenzene.
1.4.7.2 Subsurface Soil Sampling
Approximately 450 of the approximately 700 subsurface soil samples (including duplicates)
collected during the RI and RD were collected from the areas covered under this FS Report.
Subsurface soil sampling locations are presented on Figure 1.4. These samples were collected
from depths of 0.5 to 75 ft bgs, and with the exception of ten samples analyzed for only
dioxins and furans, they were analyzed for the same constituents as the surface soil samples.
1.4.7.3 Soil Gas Sampling
During the RI, 34 soil gas samples (including four duplicates) were collected from 16 soil
borings. These samples were collected using Summa® canisters at two depth intervals: surface
(0- to 6-inches bgs) and subsurface (6-inches to 4-ft bgs). Of these 34 samples, 24 (including
all of the duplicates) were collected from areas covered under this FS Report. Soil gas
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sampling locations are presented on Figure 1.4. The soil gas samples collected during the RI
in September 2004 were analyzed for TCL VOCs, as well as the following flex clause
constituents: 1,2,3-trichlorobenzene; 1,3,5-trichlorobenzene; 1,2,3,4-tetrachlorobenzene;
1,2,4,5-tetrachlorobenzene; and pentachlorobenzene.
An additional 226 passive soil gas samples were collected and analyzed for TCL VOCs during
the RI to screen for subsurface contaminants and optimize placement of subsurface soil
borings. These samples show areas that have comparatively high contaminant concentrations,
but they do not provide soil gas concentration data and provide data only for VOCs.
Consequently, the results from these samples cannot be compared to the PRGs and were not be
used to delineate the affected areas.
1.4.8 Interim Groundwater Remedy
Previous investigations determined that contaminated groundwater from the portion of the
Columbia Aquifer that underlies the SCD Site was impacting Red Lion Creek, located north of
the SCD Site, and, potentially, the underlying Potomac Aquifer. The IGR for the Columbia
Aquifer was constructed under OU-1. The IGR included construction of a subsurface bentonite
barrier wall, and a Groundwater Extraction and Treatment System (GETS). As part of the
IGR construction activities, the two contaminated soil piles from the 1986 spill were placed,
along with the more heavily contaminated spoils from the containment barrier installation, into
in a lined and capped temporary soil storage area (TSSA) located in the northern portion of the
SCD Site (Figure 1.2).
1.4.8.1 Groundwater Containment Barrier Wall
The subsurface soil-bentonite slurry wall (containment barrier) and the associated GETS were
constructed as part of the SCD IGR under OU-1. The IGR was implemented to prevent the
migration of site related groundwater contamination within the Columbia Aquifer and from the
Columbia Aquifer to the Potomac Aquifer. Installed in 2006/2007, the containment barrier is
5,290 feet long, surrounds approximately 35 acres, and extends to an average depth of 70 ft
(Figure 1.2). Where feasible, spoils from the barrier construction trench were incorporated
into the soil-bentonite slurry. Where contaminant levels in the trench spoils precluded their use
in the slurry, the spoils were stored in the TSSA.
1.4.8.2 Groundwater Extraction and Treatment System
The GETS was completed in June 2007 and is being used to lower the groundwater elevation
within the area surrounded by the barrier wall and reduce the potential for additional
contamination in the Columbia Aquifer to spread to the Potomac Aquifer. Additionally,
approximately 450,000 gallons of contaminated water from the lined sedimentation basin has
been pumped to the GETS for treatment.
The GETS includes six extraction wells, six piezometers, a treatment system building,
conveyance piping and a groundwater treatment system as specified in the IGR design
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documents (Black & Veatch, 2005). The GETS withdraws contaminated groundwater from the
portion of the Columbia Aquifer that lies within the containment barrier and treats extracted
groundwater through the use of an air stripper, green sand filtration, and two 2,500-pound
granular activated carbon (GAC) filters. Off-gas from the air stripper is treated using two
10,000-pound GAC vessels before being discharged to the atmosphere. Treated groundwater
is discharged outside the barrier and flows to Red Lion Creek under an NPDES permit
equivalence.
The IGR also provides for the removal of DNAPL from the Columbia Aquifer. Specialized
DNAPL recovery pumps are present on site and have been used to help with this recovery,
however the distributed nature of the DNAPL and extremely slow rates of recharge at the
identified accumulation points has hampered recovery efforts.
1.4.9 Ongoing Sampling Activities
In addition to the remedial activities described above, the following routine sampling activities
related to OU-3 are conducted at the SCD site (HGL, 2008):
• Quarterly Groundwater Sampling - samples are collected from 18 of the groundwater
monitoring wells and analyzed for TAL metals, TCL VOCs, TCL SVOCs, the
aforementioned flex clause constituents, and water quality parameters.
• Semiannual Stormwater Sampling - one aqueous sample is collected from the eastern
stormwater outfall and one from the western stormwater outfall. These samples are
analyzed for PCBs using the congener-specific 1668A method (or Contract Laboratory
Program (CLP) equivalent). Once a year, in addition to the PCB congeners, the
stormwater outfall samples are analyzed for TCL VOCs, TCL SVOCs, the flex clause
constituents, iron, lead, copper, zinc, and hardness.
• GETS Performance Monitoring - monthly samples of treated effluent and off gas are
collected to characterize performance of the GETS.
1.5 NATURE AND EXTENT OF CONTAMINATION
The analysis in this FS Report is based on the soil and soil gas data for OU-3 presented in the
August 2007 RI Report. The RI Report covers samples that were collected as a part of RI field
activities from August to November 2004 and RD investigations from November 2002 to May
2003. The nature and extent of contamination for each of the areas of concern (On Facility
and Northern Area) are briefly summarized in this section. Sample locations are presented on
Figure 1.4 of this FS Report. Data collected during the 2002-2003 and 2004 investigation for
the other OUs are not discussed in this FS. A more complete discussion of site contamination
can be found in the RI Report (Black & Veatch 2007a).
1.5.1 On Facility Contamination
The On Facility portion of the SCD Site incorporates all areas located within the former
facility fence line. The On Facility area encompasses 25 acres and includes the following
features that have been identified through sampling or historical knowledge as known or
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suspected "hot spots" of contamination:
• PCB concentration area (where off-specification product was handled)
• Catch basin #1
• Former rail siding and loading area
• Warehouse and the area to the north of the warehouse
• 1986 tank collapse area
• Facility storm drains
• Drum cleaning area
• Northern end of eastern drainage ditch
• Northeast tank farm
• Former WWTP
• Process area
1.5.1.1 Surface and Subsurface Soil Contamination
Fifty-three surface soil samples and approximately 450 subsurface soil samples (including
duplicates and quality controls) were collected from locations in the On Facility area during the
RI and RD sampling events. The analytical results and summary statistics for the surface soil
and subsurface soil samples are presented in Tables 4-6, 4-7, 4-8, and 4-9 of the RI Report
(Black & Veatch, 2007a). The samples were analyzed for one or more of the following
constituents:
• TCL volatile and semivolatile organics;
• TAL inorganic constituents (including cyanide);
• The following flex clause constituents: 1,2,3-trichlorobenzene, 1,3,5-trichlorobenzene,
1,2,3,4-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, and pentachlorobenzene;
• TOC; specific gravity; and percent moisture content;
• CLP TCL pesticide/PCBs;
• Dioxin/furans
Overall, the highest levels of contamination were observed in the On Facility area.
VOCs
The VOCs detected most frequently and at the highest concentrations in the On Facility area
soil included benzene, chlorobenzene, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,3-
dichlorobenzene, 1,2,3-trichlorobenzene, and 1,2,4-tichlorobenzene. The following On Facility
soil sample locations were identified with elevated concentrations of these VOCs (Black &
Veatch 2007a):
• 1,2,3-Trichlorbenzene: RD surface soil samples SS-01-F (1,300 mg/kg) and SS-05-F (410
mg/kg); and RI samples NESB-13A (45 mg/kg), NESB-16A (25 mg/kg), and RAS-10A
(23 mg/kg).
• 1,2,4-Trichlorbenzene: RD surface soil samples SS-05-F (1,100 mg/kg), LT-5 (26
mg/kg), LT-3 (38 mg/kg), LT-8 (91 mg/kg) and SS-01-F (980 mg/kg); and RI samples
NESB-40A (90 mg/kg), RAS-10A (88 mg/kg).
• 1,2-dichlorobenzene, 1,4-dichlorobenzene, and 1,3-dichlorobenzene showed similar
spatial patterns in their distribution.. Sample SS-01-F, collected along the rail siding
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area during the RD, contained the highest site-wide concentrations of 1,2-
dichlorobenzene (570 mg/kg), 1,4-dichlorobenzene (1,300 mg/kg), and 1,3-
dichlorobenzene (250 mg/kg). Sample NESB-13A, collected near the WWTP during
the RI, also contained the highest site-wide concentration (570 J mg/kg) of 1,2-
dichlorobenzene. 1,2,4-trichlorbenzene, 1,2-dichlorobenzene, 1,4-dichlorobenzene,
and 1,3-dichlorobenzene were similar in their distribution and showed substantially
higher concentrations in RI soil boring sample NESB-11, shallow subsurface sample
RAS-10B (2 to 4 ft bgs), and RD samples SB-02 through SB-05 and SB-08 than in
other subsurface surface soil samples collected from the On Facility area.
• Chlorobenzene was generally not-detected or detected at low concentrations in most
surface soil samples in the On Facility area. Exceptions included samples NESB-20
(2.0 mg/kg), NESB-13 (13 J mg/kg), and RD samples LT-7 (2.9 mg/kg), SS-07-F (3.0
mg/kg), which contained substantially higher concentrations of chlorobenzene. In
subsurface soils, soil borings with elevated concentrations of chlorobenzene included
NESB-11, NESB-02, NESB-06, NESB-07, NESB-09, NESB-12, NESB-13, NESB-19,
NESB-23, NESB-24; samples collected in the area of Catch Basin 1 (SB-02, SB-04,
SB-05); and sample SB-08.
• Benzene was generally not-detected or detected at low concentration in most of the
surface soil samples collected in the On Facility area. Soil boring samples NESB-06
NESB-11, NESB-12, NESB-13, NESB-23, NESB-24, NESB-25, and NESB-40
contained elevated concentrations of benzene in several depth intervals.
SVOCs
Generally, SVOCs were detected infrequently or at low concentrations in most surface and
subsurface soil samples from the On Facility area. Exceptions include 1,2,3,4-
tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, hexachlorobenzene, pentachlorobenzene, and
bis(2-ethylhexyl)phthalate which were detected most frequently and at the highest
concentrations. In addition, elevated concentrations of di-n-butylphthalate, fluoranthene,
phenanthrene, and pyrene were detected in some surface soil samples.
Surface soil samples from the On Facility area with elevated concentrations of SVOCs included
RI samples NESB-10, NESB-12, NESB-15, NESB-20, NESB-26, RAS-1A, RAS-6A, and
RAS-10A, and RD samples LT-1, LT-2, LT-3, LT-5, LT-6, LT-7, LT-8, LT-12, LT-13, SS-
05-F, SS-06-F, and SS-07-F. The most frequently detected polycyclic aromatic hydrocarbons
(PAHs) in surface soil samples collected from the On Facility area included fluoranthene,
phenanthrene, and pyrene. Surface soil samples that contained substantially elevated
concentrations of these PAHs included RI samples NESB-12, NESB15, NESB-20, NESB-26
and RAS-6A, and RD samples LT-1, LT-2, LT-6, LT-7, LT-12, SS-06-F, and SS07-F.
Subsurface soil samples that contained substantially higher concentrations of SVOCs included
RI boring samples NESB-02, NESB-05, NESB-06, NESB-07, NESB-08, NESB-09, NESB-11,
NESB-12, NESB-13, NESB-16, NESB-24, and NESB-25; shallow subsurface samples RAS-
1B, RAS-3B and RAS-10B; and RD samples SB-02 and SB-03. The spatial distribution of
these sample locations was generally widespread across the facility, and the contamination
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occurred at several varied depth intervals.
Pesticides and PCBs
Selected soil samples collected during the RD and RI were analyzed for pesticides and PCBs.
Pesticides and PCBs were generally not-detected or detected at low concentrations in most soil
samples collected from the On Facility area.
The samples with elevated concentrations of one or more pesticides in surface soil included
sample RAS-4A behind the warehouse, sample RAS-6A behind the tank farm near the eastern
drainage ditch, and sample LT-5 in the former PCB concentration area. In addition, RD
sample SB-02 contained elevated concentrations of alpha-BHC, endosulfan, and heptachlor in
subsurface soil.
PCBs were generally not-detected (using EPA Method 8081) with the exceptions of a few
sporadic detections of Aroclor 1248 (0.084 mg/kg in RAS-6B and 0.085L mg/kg in RAS-10B),
Aroclor 1254 (0.040J mg/kg in RAS-9B), and Aroclor 1260 (0.130J mg/kg in RAS-1B). In
addition, elevated concentrations of Aroclor-1242 were detected in RD samples SS-07-F, SS-
08-F, SS-06-F, SS-01-F, and SS-05-F.
EPA Method 8081 (employed in the analysis of OU-3 soil samples) determines PCB
concentrations by matching groups of PCB congeners (species) to the groupings that were
found in commercial PCBs (i.e., Aroclors). EPA Method 1668A detects and reports the
concentrations of all 209 individual PCB congeners, is less likely to be impacted by matrix
interferences, and is more sensitive than Method 8081. Analyses of wetlands materials and site
groundwater using EPA Method 1668A showed significant PCB contamination in areas where
previous analyses using EPA Method 8081 had failed to detect any. The lack of OU-3 PCB
data generated using method 1668A represents a possible data gap that would have to be
addressed before a definitive determination of site risks related to these compounds can be
made.
Inorganics
With the exception of cadmium, cyanide, selenium, and thallium, all TAL inorganics were
detected in almost every surface soil sample. All TAL inorganics (including cyanide) were
detected in at least one subsurface soil sample collected from the On Facility area. Most of the
samples collected from the On Facility area contained concentrations of inorganics that
exceeded twice the calculated background/reference concentrations, indicating that the
observed concentrations of inorganics could be site-related (Black & Veatch, 2007a).
Following a statistical analysis of the inorganic contaminant data (performed as part of the
BLRA), it was determined that only aluminum, chromium, iron, and manganese concentrations
at the site could be attributed to background.
Antimony, beryllium, selenium, silver, and sodium showed the most exceedances when
compared to background/reference concentrations. Samples RAS-6B, NESB-3, NESB-13,
NESB-14, NESB-15, and NESB-25 contained the highest numbers of exceedances when
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compared to background/reference concentrations. These samples are located in the
northeastern corner of the site (RAS-6B and NESB-25), near the WWTP and eastern boundary
of the site (NESB-13, NESB-14, NESB-15), and in the former process area (NESB-3).
Dioxins/furans
Total 2,3,7,8-tetrachlorodibenzodiozin (TCDD) toxic equivalents (TEQs) in surface soil ranged
from 89 picograms per gram (pg/g) in RI sample RAS-2A to 26,769 pg/g in sample RAS-4A.
The highest concentrations were observed in RI samples RAS-4A, and RAS-6A, and RD
sample DF. Samples DF and RAS-6A are located in close proximity to each other, behind the
tank farm near the eastern drainage ditch in the northeast corner of the facility, and sample
RAS-4A is located behind the warehouse (Black & Veatch, 2007a).
Total 2,3,7,8-TCDD TEQs in subsurface soil ranged from 11 pg/g in RI sample RAS-8B to
279 pg/g in RI sample RAS-7B. Concentrations of dioxins/furans were substantially higher in
RI subsurface soil samples RAS-7B (former loading area) and samples RAS-10B and RAS-01B
(process areas) than in other samples collected from the On Facility area (Black & Veatch,
2007a).
1.5.1.2 Soil Gas Contamination
Thirty-four soil gas samples (24 from On Facility and 10 from Off Facility areas) were
collected from two depth intervals (0- to 6-inch and 6-inch to 4-foot) and analyzed for VOCs
during the RI investigations. Four samples (RAS-15A/B and RAS-16A/B) were collected from
off site locations to represent background/reference locations assumed to be unaffected by site
activities. The soil gas sample locations are presented in Figure 1.4. The analytical results and
summary statistics for soil gas are presented in Table 4-10 and Table 4-11 of the RI Report,
respectively (Black & Veatch, 2007a).
The highest concentrations of detected chemicals were generally from samples collected from
On Facility locations within the 6-inch to 4-foot depth interval. The VOCs detected most
frequently and at the highest concentrations included benzene, 1,2-dichlorobenzene, 1,4-
dichlorobenzene, and 1,3-dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene,
carbon tetrachloride, chloroform, tetrachloroethene, and xylenes. These chemicals were
typically detected in all of the soil gas samples collected at the site (both On Facility and Off
Facility areas).
Soil gas concentrations were highest for all of the site-related VOCs in samples collected from
location RAS-10 in the former process area. Soils collected from this location also contained
elevated concentrations of VOCs, SVOCs, inorganics, and dioxins/furans. Samples from
locations RAS-2 and RAS-9 (which are located in the vicinity of RAS-10) also had
considerably higher concentrations of the site-related VOCs when compared to the other soil
gas samples (Black & Veatch, 2007a).
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1.5.2 Northern Area Contamination
Most of the off-facility sampling covered areas not addressed by this FS. Therefore, there are
limited data available to characterize the nature and extent of contamination found in the
Northern Area. Drum segments and solidified puddles of chlorobenzenes were found near the
northern border of the On Facility area during construction of the Western Stormwater Basin.
Because the contamination related to these discoveries was not delineated during these
construction activities, there is a concern that this apparent dumping area might extend
northward beyond the former facility fence line.
During the RI, soil was sampled from multiple depths at three locations within the Northern
Area. Six chlorobenzene compounds were detected at relatively low concentrations (total
concentration of 2.06 mg/kg) in a surface sample collected from one of the three locations
(NESB-28) in this area. No other COCs were detected in any samples collected from these
locations. No dioxin or active soil gas samples were collected from this area. All of the
passive soil gas samplers that were deployed in this area exhibited no or relatively low levels
of contaminants.
1.6 CONTAMINANT FATE AND TRANSPORT
The main sources of contamination at the site include:
• Contaminated surface and subsurface soils at the SCO facility
• Contaminated groundwater under the SCD facility
• Contaminated wetland sediments in Red Lion Creek and its unnamed tributary
• Residual contaminants deposited on the site during plant operations
This section summarizes the fate and transport potential for site-related contamination with the
emphasis on the potential spread of contamination from and to the OU-3 soil and soil gas.
Detailed discussion of contaminant fate and transport, including the chemical-specific fate and
transport characteristics of the main COCs, can be found in the RI Report (Black & Veatch,
2007a)
The migration pathways from the source areas include air migration pathways, surface water
flow and sediment transport pathways, and groundwater flow pathways. Each of the potential
migration pathways is briefly described below. The RI Report (Black & Veatch, 2007a) can be
consulted for further details.
1.6.1 Air Migration
The principal COCs for the air migration pathway include chlorinated benzenes, benzene,
dioxins, and PCBs. Although a major portion of the VOCs likely volatilized into the
atmosphere shortly after they were spilled or leaked from their containers, the presence of
VOCs and SVOCs in surface and subsurface soils indicates the potential for vapor intrusion
into the facility warehouse, GETS building, or future buildings at the site, or volatilization
during excavation activities. Dioxins and PCBs are not volatile. However, these compounds
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adsorb strongly to organic matter on the soil particles and can become airborne if these soil
particles become dust emissions either through wind erosion or construction activities.
The potential for dust migration from areas of the former manufacturing facility that are
covered by impervious surfaces or grass, brush, or ballast is minimal since there are no large
areas of bare earth susceptible to wind-blown redistribution. The former eastern bone yard
(located east and southeast of the largest tank farm) and the northern bone yard (located to the
north of the warehouse) are mostly bare earth with minimal vegetation. Construction activities
related to the IGR have covered portions of these areas with imported fill, but there is still a
potential for dust migration from these two areas. In recent years, with the ongoing demolition
and GETS construction activities occurring at the site, there have been small areas of exposed
soil and stockpiles that would be susceptible to wind-blown redistribution. Wind directions at
the site are highly variable depending on the season and local weather conditions, with
prevailing winds from the west. Based on the prevailing wind direction, distribution and
settling of this contaminated dust would be expected to be more significant to the east of the
site in the direction of the Occidental Chemical plant and the Delaware River.
1.6.2 Surface Runoff and Migration
The majority of site-related COCs available for migration via the surface water pathway are in
sediments of the wetlands bordering the Red Lion Creek and its tributary as well as at the
bottom of Red Lion Creek itself. With respect to the OU-3 area, surface water migration of
COCs occurs primarily through the transport of surface soils and sediments in stormwater
runoff.
As discussed in Section 1.3.1, the site's storm water management system has been altered
substantially as a result of demolition and IGR construction activities. The vast majority of the
stormwater drains that used to service the facility area have been destroyed or otherwise
rendered inoperable. In their place a system of drainage swales and ditches route stormwater
to one of two stormwater and sediment control basins. The western basin discharges site
runoff through the western drainage gully and into the unnamed tributary wetlands, while the
eastern basin discharges stormwater overland to the wetlands that lie to the east of the upland
portion of the site. Stormwater and suspended sediments from the site and the discharge
pathways is transported downgradient, eventually reaching Red Lion Creek. The Red Lion
Creek discharges to the Delaware River approximately one mile east of the site. A tide gate at
the mouth of the Red Lion Creek was installed to eliminate or minimize the tidal effects of the
Delaware on the creek and prevent the transport of contaminated sediments from the site to
upstream areas (Black & Veatch, 2007a).
Because of certain chemical properties of most site contaminants and dilution in the Red Lion
Creek, detected concentrations of COCs in surface water have been, as expected, low relative
to those found in the groundwater and site soils. Chlorinated benzenes having three or more
chlorines in their structure (i.e., trichlorobenzenes, tetrachlorobenzenes, pentachlorobenzene,
and hexachlorobenzene), dioxins, and PCBs are strongly bound to organic material in the soil.
Chlorobenzene and benzene are not strongly bound to soil/sediment, but they are volatilized
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readily and undergo degradation processes more readily than their more chlorinated
counterparts. The more highly chlorinated benzene compounds, dioxins, and PCBs are known
to bioaccumulate, and possibly biomagnify in food chains. Therefore, organisms closely
associated with contaminated sediment (wading birds, amphibians, fish, and invertebrates) may
potentially accumulate contamination from the site and transport bioaccumulative COCs into
food chains (Black & Veatch, 2007).
1.6.3 Groundwater Migration
Portions of the Columbia Aquifer are contaminated with significant concentrations of benzene
and chlorinated benzenes. The RI Report included a statement that PCBs and dioxins would
not be expected to be significant groundwater contaminants (Black & Veatch, 2007), but
congener-specific analysis of recent Columbia Aquifer groundwater samples has shown the
presence of PCBs at concentrations up to 10 times the drinking water standard. Groundwater
from the Columbia Aquifer discharges into Red Lion Creek and there is increasing evidence of
a hydraulic connection between the Columbia Aquifer and the underlying Potomac Aquifer.
These facts prompted implementation of the IGR (see Section 1.4.8). The IGR includes the
GETS and a groundwater containment barrier. The GETS is being used to lower the Columbia
Aquifer groundwater elevation within the containment barrier alignment and impart an upward
gradient between the Potomac and Columbia aquifers. Because of the installation of the
containment barrier and the lowering of the Columbia Aquifer, the potential for migration of
contaminants from the on-facility soil via the groundwater pathway is not expected to be
significant.
1.7 SUMMARY OF BASELINE RISK ASSESSMENT
The Baseline Risk Assessment (BLRA) Report (Black & Veatch, 2007) for the SCD site
includes detailed information on the human health and ecological risk assessment conducted in
2004. The findings of the BLRA Report are summarized in the following sections.
1.7.1 Human Health Assessment
The Human Health Risk Assessment (HHRA) was conducted in accordance with the EPA Risk
Assessment Guidance for Superfund (RAGS) - Volume I Human Health Evaluation Manual,
Part A (EPA, 1989), Part D, Standardized Planning, Reporting and Review of Superfund Risk
Assessments (EPA, 2001), and other appropriate guidance (Black & Veatch, 2007).
1.7.1.1 Chemicals of Potential Concern
Over 100 constituents detected in various site media were screened by eliminating constituents
detected in blanks and comparing maximum detected concentrations to risk-based screening
levels (EPA Region 3 Risk Based Concentrations). Through this process, a large number of
constituents were selected as Chemicals of Potential Concern (COPCs) for the SCD site. A
summary of the selected COPCs can be found in Tables 2.1 through 2.15 of BLRA Report
(Black & Veatch, 2007). Potential health risks and hazards were characterized based on the
selected COPCs for each relevant medium at each identified exposure area.
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1.7.1.2 Exposure Assessment
In exposure assessment, a fate and transport analysis of the COPCs in conjunction with the
source area characteristics was used to identify the potential constituent migration and exposure
pathways at the SCD site. The selected exposure pathways considered most applicable to the
SCD site include:
• Future Ingestion of COPCs in Drinking Water from Wells in Columbia and Potomac
Aquifers
• Future Dermal Absorption of COPCs in Water from Wells in Columbia and Potomac
Aquifers
• Future Inhalation of Vapors Associated with Use of Water from Columbia and Potomac
Aquifers for Showering
• Current/Future Ingestion of COPCs in Soil
• Current/Future Dermal Absorption of COPCs in Soil
• Current/Future Inhalation of COPCs in Dust
• Current/Future Inhalation of COPCs in Soil Gas Vapors (Indoor and Outdoor Air)
• Current/Future Ingestion of COPCs in Surface Water
• Current/Future Dermal Absorption of COPCs in Surface Water
• Current/Future Ingestion of COPCs in Sediment
• Current/Future Dermal Absorption of COPCs in Sediment
• Current/Future Ingestion of COPCs in Fish Tissue
• Current/Future Ingestion of COPCs in Duck Tissue
Exposure was quantified based on an analysis of the COPC exposure point concentrations for
each medium in each exposure unit. The exposure point concentrations for the reasonable
maximum exposure (RME) and central tendency exposure (CTE) are presented in RAGS D
Tables 3.1 through 3.15 of the BLRA Report (Black & Veatch, 2007). Intake was estimated
for receptors for each medium in each exposure unit. The exposure equations and assumptions
used for the calculation of chemical intakes for the RME and CTE are presented in RAGS D
Tables 4.1 through 4.24 of the BLRA Report (Black & Veatch, 2007).
1.7.1.3 Toxicity Assessment
The toxicity assessment of the BLRA Report includes derivation of toxicity values based on the
available human health toxicological health effects criteria for each COPC and for each route
of exposure identified for the SCD site. For carcinogenic effects, the available oral and
inhalation cancer slope factors and unit risk factors were identified and presented for each
constituent classified as a carcinogen by the EPA, and dermal cancer slope factors were
calculated. For chronic non-carcinogenic effects, the available oral and inhalation reference
doses and reference concentrations were identified and presented for each constituent. In
addition, dermal reference doses were calculated. The toxicity values used for each COPC in
each media and each exposure unit are presented in RAGS D Tables 5 and 6 of the BLRA
Report (Black & Veatch, 2007).
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1.7.1.4 Risk Characterization
Potential cancer risks and non-cancer hazards associated with exposures at each of the
investigated areas at the SCD site are discussed in the BLRA Report (Black & Veatch, 2007).
The BLRA indicates that site-related contamination is present in soils, soil gas, sediment,
surface water, groundwater, and fish tissue at concentrations that present an unacceptable
cancer risk or non-cancer hazard to human health. The BLRA's discussions of the human
health risks associated with the OU-3 soil and soil gas are summarized below.
The total On Facility cancer risk for exposure to OU-3 soil and soil gas ranged from 9.0E-04
for construction worker to 3.5E-02 for age adjusted resident. These risks exceed the EPA
target risk range of 1E-06 to 1E-04. The primary On Facility cancer risk drivers are total
2,3,7,8-TCDD TEQ, hexachlorobenzene, and 1,4-dichlorobenzene in soil and 1,4-
dichlorobenzene, benzene, carbon tetrachloride, chloroform, PCE and TCE in soil gas. The
total Off Facility cancer risk for exposure to OU-3 soil and soil gas ranged from 8.6E-06 for
construction worker to 2.0E-04 for age adjusted resident. These risks also exceed the EPA
target risk range of 1E-06 to 1E-04. The primary Off Facility cancer risk drivers are total
2,3,7,8-TCDD TEQ and 1,4-dichlorobenzene in soil and 1,4-dichlorobenzene in soil gas.
The total On Facility and Off Facility hazard indices exceeded one for industrial and
construction workers as well as adult and child residents, indicating the potential for a non-
cancer effect. The primary On Facility non-cancer hazard drivers are 1,2,3,4-
tetrachlorobenzene and 1,2,4,5-tetrachlorobenzene in soil as well as 1,2-dichlorobenzene and
chlorobenzene in soil gas. The primary Off Facility non-cancer hazard drivers are 1,2,3,4-
tetrachlorobenzene and 1,2,4,5-tetrachlorobenzene in soil and chlorobenzene in soil gas.
Because the Off Facility driver development was based on sampling that occurred both within
and outside the Northern Area, the cancer and non-cancer risk drivers for the Northern Area
may need to be re-evaluated if contamination in that area is further delineated through
additional sampling (possibly conducted as part of the RD).
1.7.2 Ecological Risk Assessment (Surface Soil)
The BLRA concluded that there are potential risks to ecological receptors via direct exposure
to site surface water, sediment, and surface soil. Potential food chain risks were identified
through incidental ingestion of sediment and surface soil and ingestion of contaminated food
items (plants and earthworms). The risks related to the OU-3 soil are briefly discussed here.
The BLRA Report (Black & Veatch, 2007) should be consulted for complete information.
A conceptual model defining the contaminant sources, exposure and migration pathways, and
receptors of concern was used to develop and define the seven assessment endpoints (AEs)
evaluated in the BLRA. The AEs related to the OU-3 soil are as follows:
• AE3: Protection of nutrient cycling and terrestrial invertebrate populations in surface
soils at the SCD Site (upland forest):
• AE4: Protection of herbivorous wildlife populations at the SCD Site (emergent
wetlands, open water, forested wetlands, and upland forest);
U.S. EPA Region 3
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• AE6: Protection of terrestrial vermivorous wildlife populations at the SCD Site
(upland forest).
The evaluation of AE3, AE4, and AE6 indicated of the potential for ecological risk from site-
related contaminants in terrestrial habitats associated with the SCD Site. These risks include:
reduced abundance and diversity of plants and soil organisms as a result of direct exposure to
elevated contaminant levels (AE3); and potential reproductive toxicity from bioaccumulative
contaminants absorbed by soil invertebrates and plants ingested by terrestrial herbivores (AE4)
and vermivores (AE6). Contaminants in soil at concentrations that present an ecological risk
include:
• Total chlorobenzenes and benzene • Aluminum
• Hexachlorobenzene • Chromium
• 4,4'-DDD • Copper
• 4,4'-DDT • Iron
• Total PAHs • Lead
• Fluoranthene • Mercury
• Phenanthrene • Nickel
• Pyrene • Vanadium
• Pentachlorophenol • Zinc
The BLRA indicated that uptake of a COPC by soil invertebrates is greater than that for uptake
by plants; therefore, vermivores would be more significantly exposed. As a result, remedial
goals that are protective of vermivore communities will also be protective of herbivore
communities.
U.S. EPA Region 3
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FIGURES
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HGL— Feasibility Study Report, Standard Chlorine of Delaware Site—
New Castle County, Delaware
Scale 1:44,782
Source: Delaware
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Project: E10002.10.01
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Legend
Approximate Site
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Figure 1.1
Site Location Map
Standard Chlorine of Delaware
New Castle County, Delaware
SCD FS Report
U.S. EPA Region 3
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Approximate
SCO Site
Boundary
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Temporary Soil
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Soil Bentonite
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Groundwater Treatment
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Kfl
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Eastern Drainage Ditch
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1986 Tank Collapse Area
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Filename: S:\EPA 010\PROJECTS - WORK ASSIGNMENTS'^
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Revised: 06/02/08 CW
Project: El 0002. 12. 01
Source:
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Legend
Approximate
Containment Barrier
Alignment
Figure 1.2
Site Layout
Standard Chlorine of Delaware
New Castle County, Delaware
U.S. EPA Region 3
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Soil Bentonite
Containment Barrier
Alignment
Approximate Extent
of OU-3
Filename: S:\EPA 010\PROJECTS - WORKASSIGNMENTS^002
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Revised: 06/02/08 CW
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Legend
| | Approx. Containment Barrier
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Figure 1.3
Approximate Extent of OU-3
Standard Chlorine of Delaware
SCD FS Report
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2.0 REMEDIAL ACTION OBJECTIVES
This section provides details about the desired outcomes of the remediation of the OU-3 areas.
Overall Remedial Action Objectives (RAOs) are described first in Section 2.1. This is
followed by an examination of the government requirements that will dictate or guide the
direction of any RA conducted for OU-3 and an initial discussion of specific impacts that they
might have on the implementation of the RA. To provide target cleanup levels that ensure the
RAOs will be met by the RA, quantifiable preliminary remedial goals (PRGs) are then
developed (where possible). Finally these PRGs are used to estimate the volume of
contaminated materials that might require remediation to achieve the RAOs.
2.1 REMEDIAL ACTION OBJECTIVES
CERCLA requires that selected remedial actions attain a degree of cleanup that ensures the
protection of human health and the environment. The cleanup remedy must also be cost-
effective and provide permanent solutions. Remedial Action Objectives (RAOs) for the soil and
soil gas at the SCD site are generic goals that have been developed to achieve protection of
human health and the environment.
RAOs for Human Health;
• Prevent exposure to non-carcinogens in the soil and soil gas at concentrations that
would result in a target organ Hazard Index (HI) greater than 1 via the potential
exposure routes of inhalation, ingestion and dermal contact.
• Prevent exposure to carcinogens at concentrations that would result in a cumulative
cancer risk in excess of IxlO"5 (1E-05) via the potential exposure routes of inhalation,
ingestion, and dermal contact.
RAOs for Environmental Protection;
• Prevent risks to ecological communities exposed directly to the soil COCs and
indirectly via bioaccumulation of soil COCs in plants and earthworms.
RAOs for Limiting Further Migration of Contaminants;
• Minimize the further spread of contamination via any of the following major migration
pathways:
• Soil to groundwater
• Soil to surface water
• Soil to sediment
• Soil to air
2.2 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
Section 121 to the CERCLA as part of the Superfund Amendments and Reauthorization Act
(SARA) provides the statutory basis for including ARARs in the remedy selection process.
Section 121(d) requires that primary consideration be given to remedial alternatives that attain
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or exceed all ARARs, and that valid justification for a waiver from a requirement be presented
if the selected alternative will not meet an ARAR. SARA also provides for the inclusion of
promulgated, enforceable, state standards as ARARs as long as they are more stringent than
the related federal statutes. ARARs include:
• Any standard, requirement, criterion, or limitation under any Federal environmental
law, such as the Toxic Substances Control Act (TSCA), the Safe Drinking Water Act
(SDWA), the Clean Air Act (CAA), the Clean Water Act (CWA) the Marine
Protection, Research, and Sanctuaries Act (MPRSA), and the Resource Conservation
and Recovery Act (RCRA)
• Any promulgated standard, requirement, criterion, or limitation under a state
environmental or facility siting law, including those contained in EPA-approved
programs, which has been identified by the state to EPA in a timely manner.
ARARs consist of two sets of requirements, those that are applicable and those that are
relevant and appropriate. Applicable requirements are those substantive standards that
specifically address the situation at a CERCLA site. However, an applicable requirement need
not have been promulgated specifically to apply to CERCLA sites. When making a
determination of the applicability of a requirement, the site circumstances are compared to the
following jurisdictional prerequisites:
• Who is subject to the statute or regulation;
• What types of substances or activities fall under the authority of the statute or
regulation;
• What is the time period for which the statute or regulation is in effect; and,
• What types of activities does the statute or regulation require, limit, or prohibit.
If this comparison indicates that these prerequisites are met at the site, the requirement is
applicable.
Requirements that are not applicable must be evaluated further to determine whether they are
relevant and appropriate. Requirements that address situations sufficiently similar to the
proposed response action and are well suited to the conditions of the site are considered to be
relevant. For a complete determination of relevance and appropriateness, the following
comparisons must be performed:
• The respective purposes of the requirement and of the response action;
• The medium regulated or affected by the requirement and the medium contaminated or
affected at the site;
• The substances regulated by the requirement and those found at the site;
• The activities regulated by the requirement and the remedial action contemplated at the
site;
• Any variances, waivers, or exemptions of the requirement and their availability for the
circumstances at the site;
• The type of place regulated and the type affected by the release or action;
• The type and size of the structure or facility regulated, and those affected by the release
or contemplated by the action; and
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• Any consideration of use or potential use of affected resources in the requirement and at
the site.
In some cases, only portions of a requirement will be both relevant and appropriate.
In addition to the ARARs, information that is provided in certain federal and state criteria,
advisories, guidance, and proposed standards, though not legally enforceable, can be helpful in
selecting a site remedy and/or determining how protective the remedy will be. These "to be
considered" (TBC) requirements complement the use of ARARs but do not to compete with or
replace them (EPA, 1992).
Potential chemical-specific, location-specific, and action-specific ARARs for OU-3 are
summarized in Table 2.1. These ARARs are considered potential because they become final
only after the ROD is approved and issued. The following sections provide additional details
on the potential federal and state ARARs for OU-3.
As stated in 52 Federal Register (FR) 32497, chemical-specific ARARs typically, set health or
risk-based concentration limits or ranges in various environmental media for specific hazardous
substances, pollutants, or contaminants. At the SCD site, chemical-specific ARARs are
applicable to the contaminated site soils. If a selected remedy generates air emissions or spent
treatment media (such as spent carbon) the ARARs would apply to these as well. Similarly,
any alternative that includes generation of liquid waste that requires modifications or additions
to the GETS, or additional discharge to the surface water, must comply with the applicable
standards.
Location specific ARARs are restrictions on certain types of activities based on site
characteristics. Location-specific ARARs govern activities conducted within critical
environments such as wetlands, endangered or protected species habitats, and historic
locations.
Action-specific ARARs are usually technology or activity based directions or limitations that
control actions taken at hazardous waste sites. Action-specific ARARs are triggered by the
types of actions under consideration.
The following are the ARARs that have been identified for OU-3:
Resource Conservation and Recovery Act, and Delaware Regulations Governing
Hazardous Waste
EPA has promulgated regulations pursuant to the Resource Conservation and Recovery Act
(RCRA), as amended in 42 USC §§6901 et seq. These regulations, and the associated
Delaware Regulations Governing Hazardous Waste (DRGHW), define hazardous waste and
regulate its handling and disposal. The RCRA regulations that are not administered by the
state of Delaware and the federally-authorized and the more stringent provisions of DRGHW
are applicable to OU-3 because some of the site soils are expected to be hazardous and will be
U.S. EPA Region 3
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treated as hazardous wastes. These regulations are applicable to contaminated site materials as
well as wastes generated during the implementation of the selected remedy (e.g., spent carbon
from any off-gas treatment units).
From 1966 until May 2002, the former chemical facility was used to manufacture nitrobenzene
and chlorinated benzenes (including chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene,
1,4-dichlorobenzene, and trichlorobenzenes). Benzene, which was used in the manufacturing
process, and highly chlorinated chlorobenzene species (tetrachlorobenzenes,
pentachlorobenzene, and hexachlorobenzene), which were generated as off-products during the
manufacturing process, are present in site soils. DRGHW Part 261 and 40 CFR Part 261
identify solid wastes that are regulated as hazardous wastes. These regulations will be used to
determine which materials must be managed as hazardous wastes. Based on the results of
remedial investigation (RI) and remedial design (RD) characterization efforts and portions of
DRGHW or the RCRA regulations [DRGHW sections 261.33(d) and (f); 40 CFR 261.33(d)
and (f)], site soils may be classified as one or more of the following waste types:
U037 - chlorobenzene
U070-1,2-dichlorobenzene
U071 - 1,3-dichlorobenzene
U072-1,4-dichlorobenzene
U127 - hexachlorobenzene
U183 - pentachlorobenzene
U207 - 1,2,4,5-tetrachlorobenzene
U169 - nitrobenzene
Alternatively, soil waste types could be classified because of toxicity characteristics if they
meet the concentration requirements specified in DRGHW § 261.24(b) and 40 CFR 261.24(b).
Based on observed concentrations in site soils, potential classifications for excavated materials
under this section include:
D021 - chlorobenzene
DO 18 - benzene
D027 - 1,4-dichlorobenzene
RCRA regulations would be superseded in those cases where Delaware has been delegated
authority from EPA to administer the law. Additionally, any state provision that is not a part of
the authorized program, and that is more stringent than the federal requirement, would also be
applicable. The following parts of the DRGHW and RCRA regulations are considered
applicable to the OU-3 alternatives at the SCO site unless otherwise noted:
• DRGHW Part 262 Subpart A (Sections 262.10-262.12) and Section 262.34 and 40 CFR
Part 262 Subpart A (Sections 262.10-262.12) and Section 262.34 establish standards for
hazardous waste determinations and regarding accumulation time, which are applicable
to generators of hazardous waste. The substantive requirements of these sections are
considered applicable to the RA activities.
• DRGHW 264 Subpart G (Sections 264.110-264.120) and 40 CFR Part 264 Subpart G
(Sections 264.110-264.120) establish standards for the closure of, and post-closure care
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for, sites containing hazardous wastes. The substantive requirements of these
regulations are applicable to any remedial alternative selected for the site.
• DRGHW Part 264 Subpart I (Sections 264.170-264.179) and 40 CFR Part 264 Subpart
I (Sections 264.170-264.179) establish requirements for containerized storage of
hazardous waste. The substantive provisions are applicable to temporary storage
containers and on-site treatment systems.
• DRGHW Part 264 Subpart L (Sections 264.250-264.259) and 40 CFR Part 264 Subpart
L (Sections 264.250-264.259) establish standards for owners and operators of facilities
that store or treat hazardous waste in waste piles. The substantive provisions of this
subpart are applicable to any soil or sediment that is excavated and stored in waste piles
before or during treatment.
• DRGHW Part 264 Subpart N (Sections 264.300-264.317) and 40 CFR Part 264 Subpart
N (Sections 264.300-264.317) establish standards for owners and operators of facilities
that store or dispose of hazardous waste in landfills. The substantive provisions of this
subpart are applicable to remedies that include on-site landfilling of contaminated soils
and sediments. The requirement to construct a liner system will not be met by a
capping alternative. Instead, any cap will be tied into the soil bentonite containment
barrier that was installed as part of the IGR. This barrier is keyed into a low
permeability layer that lies between the contaminated soils of the Columbia Formation
and the underlying drinking water aquifer (the Potomac). This method of construction
will isolate any contaminated OU-3 soils left under the cap from surrounding
uncontaminated areas. As a result, the capping alternative will attain a standard of
performance that is equivalent to the standard that would be attained through the
construction of a liner system. As a result, this ARAR is waived pursuant to 40 CFR
Section 300.430 (f)(l)(ii)(C)(4).
• DRGHW Part 263 Subpart C and 40 CFR Part 263 Subpart C establish standards for
the cleanup of hazardous waste discharged during transportation. The substantive
provisions of this subpart would be applicable to any hazardous wastes that is spilled on
site during transportation.
Clean Water Act (CWA)
The substantive requirements of the CWA's National Pollutant Discharge Elimination System
(NPDES) are applicable to alternatives that would include remedial construction activities that
could impact stormwater quality and remedies that generate water requiring treatment through
the GETS before being discharged. Previously constructed sediment and erosion control
features will be used (and upgraded as needed) to prevent/minimize sediment run off resulting
from construction activities. Stormwater must be sampled and analyzed in accordance with the
NPDES permit equivalence that is in place at the site, which is included in Appendix B. If the
selected remedy utilizes the GETS, the requirements of the NPDES permit equivalence would
have to be met.
Delaware Regulations Governing the Control of Water Pollution
The Delaware Regulations Governing the Control of Water Pollution govern point-source and
non-point source discharges to Delaware waters. The rules include requirements for permits
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and monitoring. These regulations prohibit unpermitted discharges of pollutants into surface
waters. Permits will not be obtained at the site. The substantive provisions of these regulations
are applicable for remedial actions involving treatment system discharges to surface water as
well as for stormwater discharges that impact the Red Lion Creek and its unnamed tributary.
These provisions were considered in determining the NPDES permit equivalence limits.
State of Delaware Surface Water Quality Standards
These standards set forth water quality standards for surface waters of the State. The standards
are based upon water uses that are to be protected and are considered by the DNREC in its
regulation of discharges to surface waters. In the case of the SCD Site, the designated uses of
the Red Lion Creek, along with federal drinking water standards, were considered during the
development of the NPDES permit equivalence for the site. The designated uses for Red Lion
Creek are:
Public water supply source (goal use);
Industrial water supply;
Primary contact recreation;
Secondary contact recreation;
• Agricultural water supply (fresh water segments only); and
• Fish, aquatic life, and wildlife (DNREC, 2004).
These standards are applicable to point and non-point discharges (including stormwater and
GETS effluent) from the site to surface water. The water quality standards will be complied
with as part of meeting the substantive requirements of the NPDES permit equivalence.
Coastal Zone Management Act (16 USC Section 1451) and Coastal Zone Act
Reauthorization Amendments of 1990
This Act and its Amendments require that any activities that directly affect the coastal zone and
are conducted or supported by federal agencies be performed in a manner that is consistent
with the enforceable policies of the approved state coastal zone management program.
Because the SCD Site is located in the Delaware coastal zone, the Act and the related
Amendments are applicable to the site. All RA activities will be performed, to the maximum
extent practicable, in a manner consistent with the enforceable policies of Delaware's coastal
zone management program.
Delaware Coastal Zone Act (7 Delaware Code Sections 7002-7003) and the Delaware
Regulations Governing Delaware's Coastal Zone
This statute and regulations control the location, type, and extent of industrial activities in
Delaware's coastal areas. The site is located in the coastal zone. Section E of the regulations
specifically allows the "installation and modification of pollution control and safety equipment
for nonconforming uses within their designated footprint providing such installation and
modification does not result in any negative environmental impact over and above impacts
associated with the present use." Consequently, the bulk of the activities associated with this
remedial action would be allowed. It is expected, however, that the act's prohibition on the
placement of incinerators in Delaware's coastal zone would prevent the use of on site
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incineration to treat soils. Similarly, redevelopment of the site for heavy industrial use would
be prohibited.
Archaeological and Historical Preservation Act of 1974 (16 USC Section 469)
This Act outlines requirements to guard against the loss of significant scientific, historical, or
archaeological data. This Act is considered applicable to the site and will therefore require
that an effort be made to identify any potential resources that might be put at risk by the
construction activities related to the OU-3 remedies. Because previous construction activities
have been conducted in the area being addressed under this FS Report, it is unlikely that this
ARAR will affect RA activities. However, if any such resources are identified, steps will be
taken to minimize the potential for any adverse impact.
National Historic Preservation Act (16 U.S.C § 470)
This Act, and its implementing regulations, requires that federal agency actions avoid adverse
effects on historic properties. EPA does not have any information that there are historic
properties at the site. If historic properties are found on or near the site, action will be taken to
mitigate any adverse effects on those properties resulting from the remedial activities.
Protection of Wetlands (40 CFR Section 6. 302(a))
These regulations codify the EPA policies for carrying out Executive Order 11990. These
regulations require that activities within wetlands be conducted in a manner that avoids adverse
effects, minimizes potential harm, and restores and preserves the beneficial values of these
areas. Although none of the potential OU-3 remedies include construction activities within the
site wetlands, these regulations are applicable because of the potential for stormwater runoff to
impact the wetlands surrounding Red Lion Creek and its unnamed tributary. Previously
constructed sediment and erosion control features will be used (and upgraded as needed) to
prevent/minimize sediment run off from impacting the nearby wetlands.
Delaware Regulations Governing Hazardous Substance Cleanup
Similar to CERCLA and the National Contingency Plan, the Delaware Regulations Governing
Hazardous Substance Cleanup (DRGHSC) lay out procedures for the cleaup of hazardous
waste sites. Subsection 9.3 of the DRGHSC, pertaining to surface water cleanup levels, is
applicable to the cleanup of soils, groundwater that discharges to water bodies, and surface
water at the SCO Site.
Toxic Substances Control Act
TSCA was enacted to regulate chemical substances and mixtures whose manufacture,
processing, distribution, or disposal might present an unreasonable risk of injury to human
health and the environment. The purpose of the act was to regulate commerce and protect
human health and the environment by requiring testing and necessary use restrictions on certain
chemical substances. Portions of the TSCA deal specifically with PCB remediation waste and
are applicable to this site. TSCA defines occupancy areas and identifies varying PCB cleanup
levels for these areas. The "low occupancy areas" (as defined in 40 CFR 761.3) classification
would likely suit most portions of this site following remediation. There have not been any
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samples collected that exhibit PCB concentrations greater than the 25 parts per million cleanup
level specified for low occupancy areas. These regulations also define what is considered a
"high occupancy area" and provide more stringent cleanup levels for this type of area. 40
CFR 761 provides requirements for the handling and disposal of soils contaminated with PCBs
at concentrations in excess of the regulation-specified cleanup levels.
Delaware Regulations Governing the Construction and Use of Wells
These regulations establish requirements for the construction, location, repair, use, and
abandonment of wells and pumping equipment. The substantive provisions of these regulations
are applicable to the construction, modification, and abandonment of monitoring wells,
extraction wells, piezometers, and temporary injection points. Construction, modification, and
abandonment (where applicable) of these features will be performed in accordance with the
substantive requirements of these regulations.
Delaware Statute Regarding Licensing of Water Well Contractors, Pump Installer
Contractors, Drillers, Pump Installers, Septic Tank Installers, Liquid Waste Treatment
Plant Operators and Liquid Waste Haulers.
These regulations are applicable to activities at the SCD Site. Any drilling, installation or
abandonment activities pertaining to monitoring wells, extraction wells, piezometers, and
temporary injection points will be conducted by properly licensed workers.
Delaware Sediment and Stormwater Regulations
These regulations establish a statewide stormwater and sediment management program. The
substantive provisions are applicable to stormwater from the SCD site.
State of Delaware Implementation Plans for Attainment and Maintenance of National
Ambient Air Quality Standards (codified at 40 CFR Section 52, Subpart I) and Delaware
Air Quality Management Regulations
These regulations establish ambient air and emissions standards at the state and county level
and set forth the permitting requirements for equipment and construction activities that might
discharge air contaminants into the atmosphere. The regulations are applicable to air strippers,
SVE systems, and soil gas capture systems. The substantive requirements of these regulations
will be met and vapor phase carbon will be used to treat the air stripper off-gas before
discharge to the atmosphere. If an SVE or soil gas capture system is employed as part of the
selected remedy and the system(s) is anticipated to emit pollutants at a rate greater than that
prescribed in the regulations, emissions controls (such as vapor phase carbon) will be required.
Additionally, excavation activities will implement dust suppression measures in accordance
with the regulations.
2.3 DETERMINATION OF REMEDIATION GOALS AND DESCRIPTION OF
CONTAMINATED MEDIA
2.3.1 Derivation of Risk-Based Preliminary Remediation Goals
PRGs are risk-based concentrations used as initial cleanup goals. PRGs are not the final
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cleanup standards. However, they are helpful in providing long-term targets to use during the
analysis of different remedial alternatives.
PRGs protective of both human health and environment were developed for all COCs in the
soil and soil gas. The COCs are those chemicals that were determined to pose unacceptable
human health or ecological risks in the BLRA (Black & Veatch, 2007). Development of the
human health and ecological PRGs is discussed in the following subsections. Detailed PRO
calculations are included in Appendix A of this document. PRGs were calculated separately for
the On Facility area and the Northern Area (as shown in Figure 1.2). The lowest of the
ecological and human health risk PRGs was retained as the final PRG for each COC in each
medium. The On Facility and Off Facility COCs retained for the FS are listed along with their
corresponding PRGs in Table 2.2 and Table 2.3, respectively.
It should be noted that PRGs for the Northern Area were developed using Off Facility data
from the RI. While these Off Facility data include samples from the Northern Area, additional
samples from other portions of the site are also included. It is expected that these PRGs will
be protective of human health and the environment in the Northern Area. However, if
delineation sampling conducted in the Northern Area as part of an RD for the site indicates
otherwise, these PRGs will need to be revisited.
As part of the PRG development process for OU-3 at the SCO Site the following sources of
information were considered:
EPA Region 3 Risk-Based Concentrations Table, October 2007
The EPA Region 3 Risk-Based Concentration (RBC) table provides soil concentrations that are
associated with a cancer risk of 1E-06 or a non-cancer hazard quotient of 1 for a standard
resident exposure (residential soil RBCs) or industrial worker exposure (industrial soil RBCs).
In addition, this table provides toxicological information that can be used in the development of
PRGs to protect human health.
Oak Ridge National Laboratory Ecotoxicological Screening Benchmarks (1997)
This document provides non-enforceable ecological toxicity screening levels for use in
determining ecological PRGs. Based on communications with the EPA, these benchmarks will
be considered in the development of ecological PRGs for the SCD site.
EPA Soil Screening Levels
This document provides non-enforceable ecological toxicity screening levels for use in
determining ecological PRGs. Based on communications with the EPA, these benchmarks will
be considered in the development of ecological PRGs for the SCD site (EPA, 2008).
Development of Human Health PRGs
Human health risks were established in the BLRA for the following COCs in soil and soil gas:
• Benzene
U.S. EPA Region 3
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• Chlorobenzene
• 1,4 Dichlorobenzene
• 1,2 Dichlorobenzene
• 1,2,3,4 Tetrachlorobenzene
• 1,2,4,5 Tetrachlorobenzene
• Hexachlorobenzene
• Chloroform
• Carbon tetrachloride
• PCE
• TCE
• TCDD (dioxin)
Free phase dense non-aqueous phase liquid (mobile DNAPL) has been historically detected in
several monitoring wells and extraction wells in the Columbia Aquifer across the site and
within the barrier containment. Contaminant concentrations in most of the monitoring wells
and extraction wells screened in the Columbia Aquifer and located within the barrier
containment suggest that DNAPL is located in close proximity. Therefore, PRGs for the on-
site soil to prevent the degradation of the Columbia Aquifer were not developed because a
source in the form of mobile and residual DNAPL is present throughout the aquifer on site.
Additionally, the groundwater contamination within the OU-3 area is being addressed as part
of OU-1. It is doubtful that the further leaching of soil contamination will have a substantial
negative impact on the quality of groundwater in contact with DNAPL. Consequently, this FS
employs a more general goal of minimizing infiltration of precipitation through contaminated
soils instead of developing COC-specific PRGs that address the soil to groundwater pathway.
This generalized goal can be achieved either through the removal/treatment of the
contamination or the minimization of precipitation infiltration.
PRGs based on human health risk were calculated for each medium of concern and COC
identified in the BLRA and RI. The site receptors considered were trespasser/visitor,
residential, industrial worker, and construction worker receptors. Media were combined for a
total target risk when one receptor would be exposed to both media (soil and soil gas).
For carcinogens, PRGs were calculated for two target cancer risks. The first target cancer risk
was 10~6 for each COC. The second target risk was developed to result in a total cancer risk of
10~5 across all COCs and all media. For this calculation, the target risk for each COC was
determined by dividing 10~5 by the number of carcinogenic COCs within each medium. The
10~5 target total risk was used as a maximum allowable total risk level in accordance with the
DRGHSC.
For non-carcinogens, the target HI of 1 was divided by the number of chemicals in soil and
soil gas that affected the same target organ to determine the target hazard quotient (HQ) for the
individual COCs.
Once the target risks and HQs were calculated for the COCs, PRGs were derived from the
U.S. EPA Region 3
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exposure point concentrations (EPCs) for each chemical and corresponding site risks presented
in the BLRA by solving the following equation for the PRO:
EPCI (Site Risk or HQ) = PRO I (Target Risk or HQ)
The PRO calculated using the carcinogenic 10~6 risk level was compared to the PRO for an HI
of 1, and the lower of these two PRGs was selected as the minimum end of the PRO range for
that chemical, medium, and receptor. Similarly, the PRO calculated using the carcinogenic
10~5 risk level was compared to the PRO at the HI of 1, and the lower of the two became the
maximum end of the PRO range for that chemical, medium, and receptor.
Taking into account the site history and location, the final human health PRGs were selected
based on the cumulative cancer risks of 10~5 for commercial, industrial and trespasser targets.
Although the cancer-risk trigger level for a chemical to be identified as a COC was significant
contribution to a cancer risk above 10~4, the 10~5 risk level was used in the determination of
human-health PRGs to ensure compliance with the DRGHSC. Residential PRGs were not
retained because the likelihood of the site becoming a residential property is extremely low.
Institutional Controls (ICs) prohibiting residential use will be necessary if final cleanup goals
are not based on residential (unrestricted) use.
Development of Ecological PRGs
The BLRA evaluated ecological risks resulting from several routes of exposure. For OU-3,
the only pertinent receptors are terrestrial receptors because this OU does not include any
aquatic habitat. To develop ecological PRGs for surface soil that are protective of terrestrial
receptors the following AEs and measurement endpoints (MEs) from the BLRA were
considered.
• AES - Protection of nutrient cycling and terrestrial invertebrates
• AE4 - Protection of herbivorous wildlife
• AE6 - Protection of terrestrial vermivorous wildlife
• ME3.1 - Compare surface soil concentrations to those known to adversely affect
nutrient cycling and terrestrial invertebrates
• ME4.1 - Estimate food chain exposure for terrestrial herbivores and compare to no
observed adverse effects level (NOAEL) and lowest observed adverse effects level
(LOAEL) toxicity reference values
• ME6.1 - Estimate food chain exposure for terrestrial vermivores and compare to
toxicity reference values (NOAELs and LOAELs).
It should be noted that while the BLRA grouped total chlorobenzenes and benzene as a
category, separate PRG analyses were performed for benzene and each of the individual
chlorobenzene compounds.
The BLRA did not distinguish between chemicals that resulted from background conditions
(metals) and site-related chemicals. Therefore, site-specific metals data were compared to
background concentrations. Aluminum, chromium, iron, manganese, and vanadium
U.S. EPA Region 3
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concentrations in soils within the facility fence line were reported to be statistically equal to
background levels in the BLRA. Vanadium concentrations in soils outside the facility fence
line were reported in the BLRA to be statistically equal to background levels (Black & Veatch,
2007). As a result, these metals are not included in the COC list, and samples in which these
contaminants would have been the only ones exceeding their PRGs were discounted when
calculating soil areas and volumes requiring treatment and/or containment.
Nutrient Cycling and Terrestrial Invertebrates (AE3, ME3.1)
To evaluate potential effects to nutrient cycling and terrestrial invertebrates, the BLRA
compared maximum detected concentrations in surface soil samples to the EPA Region 3
Biological Technical Assistance Group (BTAG) Soil Screening Values. Based on this
comparison, total chlorobenzenes, benzene, hexachlorobenzene, 2-methylphenol,
dichlorodiphenyldichloroethane (DDD), dichlorodiphenyldichloroethylene (DDE),
dichlorodiphenyltrichloroethane (DDT), PAHs, pentachlorophenol, aluminum, antimony,
beryllium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, thallium,
vanadium, and zinc were identified in the BLRA as potentially presenting a risk to nutrient
cycling and the soil invertebrate community (Black & Veatch, 2007). The EPA Region 3
BTAG Soil Screening Values are conservative screening levels intended to protect all potential
ecological receptors, not just soil invertebrates and microorganisms. Thus, a concentration
above this screening value might not pose a threat to nutrient cycling and the terrestrial
invertebrate community. To identify the chemicals that could pose a threat for this AE, the
following approach was used:
• Maximum detected concentrations of the compounds listed above were compared to the
Ecological Soil Screening Level (Eco-SSL) for terrestrial invertebrates, the Eco-SSL
for plants, the Oak Ridge National Laboratory (ORNL) benchmark value for
earthworms, the ORNL benchmark value for soil microorganisms/microbial processes,
and the ORNL benchmark value for plants (ORNL, 1997). The Eco-SSLs and
benchmark values are listed in Appendix A.
• Benchmark values are not available for benzene, DDD, DDE, DDT, 2-methylphenol,
thallium, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,2,4,5-tetrachlorobenzene, or
1,3,5-trichlorobenzene.
0 For the dichlorobenzenes, the concentrations of the three isomers were summed and
compared to the available benchmark value for 1,4-dichlorobenzene.
0 For 1,2,4,5-tetrachlorobenzene, its concentration was added to that for 1,2,3,4-
tetrachlorobenzene and the sum was compared to the available 1,2,3,4-
tetrachlorobenzene benchmark value.
0 1,2,3-Trichlorobenzene and 1,2,4-trichlorobenzene have the same benchmark value.
The concentrations of the three trichlorobenzene isomers were summed and
compared to 20 mg/kg, the available benchmark value for both 1,2,3-
trichlorobenzene and 1,2,4-trichlorobenzene.
0 For benzene, DDD, DDE, DDT, 2-methylphenol, and thallium, quantitative
evaluations were not performed due to the lack of benchmark values.
Based on this evaluation, chemicals were identified as COCs for nutrient cycling and terrestrial
U.S. EPA Region 3
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invertebrates. These chemicals are listed along with the results of the above screening analysis
are in Appendix A. The PRO for each nutrient cycling/terrestrial invertebrate COC is the
lowest available benchmark value.
Terrestrial Herbivores (AE4, ME4.1)
The BLRA indicated that three contaminants (copper, mercury, and zinc) present a food chain
risk to terrestrial herbivores at the site (Black & Veatch, 2007). The food chain model,
toxicity reference values (TRVs), and biotransfer factors (BTFs) presented in Tables 3-11
through 3-13 of the BLRA were used to calculate the soil concentration that would result in an
HQ of 1 for the NOAEL and LOAEL. The resulting NOAEL and LOAEL PRGs are provided
in Appendix A of this document.
Terrestrial Vermivores (AE6, ME6.1)
The BLRA indicated that 11 contaminants (copper, lead, zinc, DDD, DDT, fluoranthene,
hexachlorobenzene, pentachlorophenol, phenanthrene, pyrene, and TCDD) present a food
chain risk to terrestrial vermivores at the site (Black & Veatch, 2007). Similar to the approach
described above for terrestrial herbivores, the food chain model, TRVs, and BTFs provided in
the BLRA were used to calculate NOAEL and LOAEL PRGs. The target HQ was 1. The
calculated NOAEL and LOAEL PRGs are provided in Appendix A of this document.
The PRGs calculated for pentachlorophenol and hexachlorobenzene were less than the EPA
Region 3 BTAG Soil Screening Values (identified in Table 3-9 of the BLRA). Because of the
very low PRGs calculated for these chemicals (10~5 to 10"4 mg/kg), it was recommended that
the EPA Region 3 BTAG Soil Screening Value or the Eco-SSL for avian receptors be
identified as the PRG. The BTAG agreed that the pentachlorophenol PRG should be
established at the Eco-SSL for avian receptors (2.1 mg/kg).
2.3.2 Volume Estimates
To determine the volume of soil requiring remediation, concentrations of COCs in soil and soil
gas samples in the RI Report (Black & Veatch, 2007) were compared to the corresponding
PRGs developed as part of this FS. Locations where COCs were detected at concentrations in
excess of the PRGs are included in the area requiring remediation.
Direct contact, inhalation, and ingestion of soil particles are the main routes of human and
ecological exposure. Twelve feet is the maximum depth one would reasonably expect that any
future construction activities at the site would reach. Thus, 12 feet represents the base of the
soil for which there is a reasonable expectation of a complete exposure pathway for human
health-related risks. ICs will be required to prevent disturbance of soil below 12 feet.
Ecological risks are only expected to be relevant in the biologically active zone (considered to
be from 0 to 2 feet bgs). As a result, the vertical depth of the soil contaminant concentration
to PRG comparison was limited to 12 feet bgs for human-health driven PRGs and 2 ft bgs for
ecologically driven PRGs. In those areas where a surface sample represents the only available
data and contaminants exceeded the human health PRGs, it was conservatively assumed that
the full 12 ft depth would exceed the human health PRG.
U.S. EPA Region 3
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Locations with samples collected at depths up to 12 ft bgs that have COC concentrations above
one or more PRGs are presented on Figure 2.1. This figure shows widespread contamination
throughout the facility portion of the site. Based on the distribution of contamination, it is
expected that the entire area within the former facility fence line will require remediation. A
review of the mapped data revealed that samples from 54 of the 65 locations within the former
facility area had at least one contaminant present at concentrations greater than its PRO. This
includes 30 of the 40 locations where subsurface soil samples were collected at depths up to 12 ft
bgs. Soil gas concentrations exceeded at least one PRO in samples collected from eight of the 10
locations where soil gas samples were analyzed.
Although 25 dioxin samples were collected from 15 locations within the former facility fence line,
subsurface data are only available for 10 of these sample locations (See Figure 2.2).
Additionally, all of the subsurface data are from samples that were collected from depth intervals
of 2 to 4 ft bgs. Dioxins were detected at concentrations greater than the PRO in 14 of the 15
surface soil samples and 8 of the 10 subsurface samples. While dioxins are not typically very
mobile in soils, the lack of data from depths greater than 4 ft, combined with the prevalence of
subsurface exceedances in the available data, makes it difficult to rule out the possibility that
dioxin contamination could extend to the 12 foot depth limit on the soil identified for remediation.
It should be noted that in nine of the 10 locations where surface and subsurface (2 to 4 ft bgs)
dioxin data are available, concentrations decreased substantially (by a median factor of 4.54) with
depth. One additional dioxin sample was collected as a background sample just outside the
facility fence line in the southeast corner of the SCD Site property. Dioxin levels in this surface
soil sample exceeded the dioxin PRO.
One possible area that might not require remediation is the far southwest corner of the facility
(an area of less than one acre) where none of the samples from boring NESB-1 had COCs
present at concentrations greater than their respective soil PRGs. An additional soil boring
(SB-1) from this area also was free of contaminants at concentrations greater than the PRGs,
but this sample was collected from a depth of approximately 30 ft bgs. Although there are a
few locations to the north of the warehouse where contaminant concentrations in samples did
not exceed the PRGs, these are either adjacent to locations with samples that exceeded the
PRGs or in areas with other evidence of contamination (such as the drum remnants and waste
material found to the north of the warehouse).
2.3.2.1 Volume to Address Soil Risk
From a soil contamination perspective, it appears that any remedy will need to address the
entire portion of the facility area that lies within the containment barrier (22.8 acres). In
general, the data indicate that the remedy will need to address soils to a depth of approximately
12 ft across the vast majority of this area, although it appears that some areas might only
require remediation to depths of approximately 2 ft bgs to mitigate soil risks. These areas
include the southwest corner of the facility (approximately 1.6 acres), portions of the area
between and to the north of the warehouse and the northeast tank farm (approximately 1.6
acres), and an area along the eastern fence line extending from north of the drum cleaning area
U.S. EPA Region 3
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to the northern facility boundary (approximately 2.4 acres). Taking into account these reduced
depth areas, the volume of site soils requiring RA to address soil risks (excluding those from
soil gas) equals 351,060 cubic yards.
2.3.2.2 Volume to Address Soil Gas Risk
In the calculation of soil volumes requiring remediation to address soil gas risks, all soils
within the vadose zone were considered to be contributory to detected soil gas contaminant
levels. As discussed earlier, the GETS is being used to lower the groundwater elevation within
the walled area, so the future depth to groundwater is expected to be approximately 50 ft bgs.
An initial volume calculation approach assumed that a 50-ft radius around each of the soil gas
sample locations where at least one contaminant exceeded its PRO would require remediation
to a total depth of 50 ft (the expected depth to groundwater resulting from the ongoing GETS
operation). Because of the limited available soil gas sample data and the fact that the
suspected/known "hot spots" listed above overlapped the soil gas sample locations, this
approach was altered to one in which all vadose zone soils associated with each of the "hot
spots" (with the exception of the warehouse) were assumed to require remediation to a total
depth of 50 ft. For the purposes of these volume calculations, approximately half of the soils
underlying the warehouse and its surrounding area were assumed to be contaminated.
Estimated areas of contamination associated with each hot spot were obtained from AutoCAD*
using the surveyed site map with a minimum area of 10,000 square ft assigned for each area in
question. The revised method resulted in an estimate of 464,650 additional cubic yards
requiring remediation to address risks related to soil gas. When combined with the volume of
soil requiring remediation to address soil risk, a total remedial soil volume of 815,710 cubic
yards is expected for the on facility area. The fact that eight of the ten soil gas samples from
the On Facility area had at least one contaminant present in excess of its PRO might indicate
that additional soil volumes within the facility fence line will require remediation.
2.3.2.3 Volume to Address Potential Northern Area Risk
Using a worst case scenario for risks from soil in the Northern Area portion of OU-3, it is
estimated that an additional 1.4 acres of soils (beyond those found within the former facility
fence line) will need to be addressed to a depth of 12 ft. Inclusion of the Northern Area thus
adds 26,700 cubic yards to the volume requiring remediation for soil risks. Similarly, a worst
case scenario wherein all of the soils in the 1.4 acre Northern Area portion of OU-3 would
need to be remediated to address risks from soil gas yields a total of 111,000 cubic yards of
soil from the area that would require treatment. Based on the available soil data and passive
soil gas sampler data from the Northern Area, it is unlikely that such worst case scenarios
would be observed. For this reason, the volumes related to remedial measures necessary to
address soil and soil gas risks from the Northern Area portion of OU-3 have been broken out
separately. Table 2.4 provides a summary of the area and volume estimates for the soils
requiring remediation.
U.S. EPA Region 3
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2.3.2.4 Volume to Address Dioxin Risk
To develop an estimate of the volume of soil that might require additional treatment or special
handling because of dioxin contamination in excess of the PRO, the area of each hot spot was
multiplied by a depth of 12 ft. This approach was taken because of the overlap between the
available dioxin data and the listed hot spots. It is possible, based on the prevalence of dioxin
exceedances that the dioxin impacted area is underestimated by this approach, but the assumed
12 foot depth is likely conservative given the observed decreases in subsurface dioxin
concentrations with depth. Table 2.5 provides a summary of the area and volume estimates for
the dioxin impacted soils requiring remediation.
U.S. EPA Region 3
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TABLES
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Table 2.1
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3
(Page 1 of 9)
ARAR
Toxic Substances
Control Act (TSCA)
40 CFR Part 761
(particularly §§1, 3, 61,
70, 75, 202-218, 265,
272, 274)
Applicable
Establishes restrictions on the disposal
of bulk polychlorinated biphenyl
(PCB) remediation wastes.
This portion of TSCA will be
applicable if any soils excavated from
the site contain PCBs at concentrations
greater than 25 parts per million. This
concentration is based on the
assumption that the site is a low
occupancy area as defined in 40 CFR
761.3.
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Clean Water Act
(CWA): National
Pollutant Discharge
Elimination System
(NPDES)
Requirements
Clean Water Act,
Section 402: 33 U.S.C.
§1342, 40 CFR Parts
122-125
Applicable
NPDES Permit Equivalence for the
site establishes discharge limits for
surface water discharges from the
groundwater extraction and treatment
system (GETS) and stormwater
outfalls.
The substantive provisions of these
requirements are applicable to any
portion of the remedy that may affect
the water quality in the nearby wetlands
or Red Lion Creek. Previously
constructed sediment and erosion
control features will be used (and
upgraded as needed) to
prevent/minimize sediment run off
resulting from construction activities.
Water discharges will be sampled and
analyzed in accordance with the
NPDES permit equivalence in place at
the site, included in Appendix B of the
Feasibility Study Report. Discharge
limits shall be met for all onsite
discharge to surface water including
stormwater and water treated by the
GETS.
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Table 2.1
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3
(Page 2 of 9)
Delaware Regulations
Governing Control of
Water Pollution as
amended 6/23/83
Sections 7, 8, 10
Applicable
Contain water quality regulations for
discharges into surface and ground
water.
The substantive provisions are
applicable to stormwater runoff into the
unnamed tributary and Red Lion Creek.
Also applicable to discharge of treated
ground water into surface water. These
provisions were considered in
determining the NPDES permit
equivalence limits.
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State of Delaware
Surface Water Quality
Standards, as amended
July 11, 2004
Sections 1-7, 9, 10
Applicable
Standards are established to regulate
the discharge into state waters to
maintain the integrity of the water.
Applicable to stormwater runoff from
site. These standards were considered
in determining the NPDES permit
equivalence limits.
Coastal Zone
Management Act of
1972; Coastal Zone
Act Reauthorization
Amendments of 1990
16 USC 1451etseq.
15 CFR Part 930
Applicable
Requires that Federal agencies
conducting activities in or affecting
the coastal zone, conduct those
activities in a manner that, to the
maximum extent practicable, is
consistent with the enforceable
policies of the appropriate approved
State coastal zone management
program.
The substantive requirements are
applicable to this remedial action,
which is being conducted by EPA at a
facility that is located in the Delaware
coastal zone.
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Table 2.1
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3
(Page 3 of 9)
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Delaware Coastal Zone
Act; Delaware
Regulations Governing
the Coastal Zone
7 Delaware Code,
Chapter 70, at Sections
7002-7003;
Delaware Coastal Zone
Act Regulations of May
11, 1999, amended on
October 1, 2001.
Applicable
Governs permissible activities and
land uses for properties located in
Delaware's Coastal Zone. Section
7003 of the Act sets forth the uses that
are absolutely prohibited in the
Coastal Zone. Section E of the
regulations specifically allows the,
"installation and modification of
pollution control and safety equipment
for nonconforming uses within their
designated footprint providing such
installation and modification does not
result in any negative environmental
impact over and above impacts
associated with the present use."
The Site is located in the Coastal Zone.
As a result, the substantive standards of
the statute and regulations apply to this
remedy.
Preservation of
Historical and
Archeological Data
Act (or Archeological
and Historic
Preservation Act of
1974)
16U.S.C.§469
Applicable
Requires that Federal agencies take
action to recover, protect, and
preserve any significant scientific,
prehistorical, historical, or
archeological data that may be
irreparably lost or destroyed as a
result of the alteration of terrain
caused by Federal activities.
EPA does not currently have any
information that there are any
significant scientific, prehistorical,
historical, or archeological data at the
site. If EPA discovers that such data are
present at the site, actions will be taken
to comply with the substantive
requirements of this act.
The National
Historical Preservation
Act and regulations
16 U.S.C. §470;
36 CFR Part 800
Applicable
Requires that Federal agency actions
avoid adverse effects in historic
properties.
EPA does not currently have any
information that there are historic
properties at the site. If a determination
is made that there are historic
properties on or near the site, action
will be taken to mitigate any adverse
effects on those properties resulting
from the remedial activities.
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Table 2.1
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3
(Page 4 of 9)
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Delaware Regulations
Governing Hazardous
Waste (DRGHW)
SEE ITEMS 1 THROUGH 8
BELOW
The DRGHW provisions that
are a part of Delaware's
federally authorized program
would apply instead of the
federal RCRA regulations.
Additionally, any provision
that is not a part of the
authorized program, but that
is more stringent than the
federal requirement, would
also be applicable.
Applicable
Regulate the transportation,
management, treatment, and
disposal of hazardous wastes.
SEE ITEMS 1 THROUGH 8 BELOW
Regulations
promulgated pursuant
to the Resource
Conservation and
Recovery Act of 1976;
Hazardous and Solid
Waste Amendments of
1984
SEE ITEMS 1 THROUGH 8
BELOW
Federal RCRA regulations
would not apply for those
regulations where Delaware
has the authority from EPA
to administer. Federal
citations are also included in
items 2 through 8 below
because any federal
regulations that are imposed
under the Hazardous and
Solid Waste Amendments of
1984, which are not a part of
Delaware's authorized
program, and which are
immediately effective, would
apply.
Applicable
Regulates the management of
hazardous waste, to ensure the safe
disposal of wastes, and to provide
for resource recovery from the
environment by controlling
hazardous wastes "from cradle to
grave."
SEE ITEMS 1 THROUGH 8 BELOW
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Table 2.1
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3
(Page 5 of 9)
1. Identification
and Listing of
Hazardous Wastes
2. Standards
Applicable to
Generators of
Hazardous Waste
3. Standard for
Closure and Post-
Closure
4. Requirements
for Use and
Management of
Containers
DRGHW Part 261
DRGHW Part 262
subpart A (sections
262. 10-262. 12) and §
262.34;
40 CFR Part 262.
subpart A (§§262. 10-
262. 12 and §262.34)
DRGHW Part 264
Subpart G (Sections
264.110-264.120)
40 CFR Part 264 Subpart
G (§§264. 110-264. 112)
DRGHW Part 264
Subpart I (§§264. 170-
264.179)
40 CFR Part 264 Subpart
I (§§264. 170-264. 179)
Applicable
Applicable
Applicable
Applicable
Identifies solid wastes which are
regulated as hazardous wastes.
Establishes standards for generators
of hazardous wastes including waste
determination and requirements
regarding accumulation time.
Establishes standards for closure and
post-closure of hazardous waste
management facilities
Requirements for storage of
hazardous waste in storage
containers.
This part of the regulations will be used
to determine which materials must be
managed as hazardous wastes.
The substantive standards of the listed
sections would be applicable to the
residual waste generated by the
treatment of soils and sediments if the
waste generated by the treatment
system(s) is a RCRA-hazardous waste.
The substantive standards of the listed
sections would be applicable to
excavated soils if they are to be
disposed in an onsite landfill.
The substantive provisions of this
subpart are applicable to the capping of
the contaminated soil at the site.
The applicable substantive provisions
of this subpart are applicable for
temporary storage containers and on-
site treatment systems.
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Table 2.1
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3
(Page 6 of 9)
5. Standards for
owners and
operators of
facilities that store
or treat hazardous
waste in waste
piles
DRGHW Part 264
Subpart L (§§ 264.250 -
264.259)
40 CFR Part 264 Subpart
L (§§ 264.250 -
264.259)
Applicable
Requirements for storage or treatment
of hazardous waste in waste piles.
The substantive provisions of this
subpart are applicable to any soil and
sediment that are excavated and stored
in waste piles prior to or during
treatment.
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6. Standards for
owners and
operators of
facilities that store
or dispose of
hazardous waste in
landfills
DRGHW Part 264
Subpart N (§§ 264.300-
through264.317)_
40 CFR Part 264 Subpart
N (§§ 264.300 through
264.317)
Applicable
Requirements for storage or disposal
of hazardous waste in landfills.
The substantive requirements of this
subpart are applicable to on-site
landfilling of soils and sediments. The
requirement to construct a liner system
will be waived. Instead, any cap will be
tied into the soil bentonite containment
barrier that was installed as part of the
IGR. This barrier is keyed into a low
permeability layer that lies between the
contaminated soils of the Columbia
Formation and the underlying drinking
water aquifer (the Potomac). This
method of construction will isolate any
contaminated OU-3 soils left under the
cap from surrounding uncontaminated
areas. As a result, the capping
alternative will attain a standard of
performance that is equivalent to the
standards that would be attained
through the construction of a liner
system as allowed under 40 CFR §
300.430(f)(l)(ii)(C)(4).
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Table 2.1
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3
(Page 7 of 9)
7. Air emission
standards for
process vents for
owners and
operators of
facilities that treat
or dispose of
hazardous waste.
DRGHW part 264,
Subpart AA (§§
264.1030-264.1034)
40 CFR Subpart AA (§§
264.1030-1034)
Applicable
Applies to process vents associated
with air stripping operations that treat
hazardous wastes.
The substantive requirements of this
subpart are applicable to treatment
options that result in air emissions of
VOCs.
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8. Standards
applicable to
transporters of
Hazardous Waste
DRGHW Part 263,
Subpart C
40 CFR Part 263,
Subpart C
Applicable
Establishes standards for the cleanup
of hazardous waste discharged during
transportation.
The substantive provisions of this
subpart would be applicable to residual
waste generated by the treatment of
soils and sediments, if such waste is
spilled on site during transportation.
Delaware Regulations
Governing Hazardous
Substance Cleanup,
9/96, as amended
02/2002
Subsection 9.3
Applicable
Establishes surface water cleanup
levels.
Applicable to the cleanup of soils,
groundwater that discharges to water
bodies, and surface water at the site.
State of Delaware
Regulations Governing
the Construction and
Use of Wells,
February 1997
Sections 1-6, 8-10
Applicable
Contains requirements governing the
location, design, installation, use,
disinfection, modification, repair, and
abandonment of all wells and
associated pumping equipment.
Any GETS or monitoring well
modifications or repairs needed to
implement OU-3 remedy will be done
in accordance with the substantive
requirements of the well regulations.
No permits will be obtained for on site
work.
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Table 2.1
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3
(Page 8 of 9)
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State of Delaware
Statute Regarding
Licensing of Water
Well Contractors,
Pump Installer
Contractors, Drillers,
Pump Installers, Septic
Tank Installers, Liquid
Waste Treatment Plant
Operators and Liquid
Waste Haulers.
7 Del. Code §6023
Applicable
Requires that those who install,
maintain, repair, and remove wells
and associated pumping equipment be
licensed.
Any GETS or monitoring well
modifications or repairs needed to
implement the OU-3 remedy will be
done by qualified workers.
Delaware Sediment
and Stormwater
Regulations, 01/23/91,
as amended April 11,
2005
Section 1-3, 10, 11, 12,
13, 15
Applicable
Establishes a statewide sediment and
Stormwater management program.
The substantive provisions of this
regulation are applicable to Stormwater
from the site. No permits or plans will
be obtained or prepared.
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Table 2.1
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3
(Page 9 of 9)
ARAR
Legal Citation
ARAR Class
Requirement Synopsis
Applicability to Proposed Remedies
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Delaware Air Quality
Management
Regulations
Air Quality Management
Regulations Number
1102 (Section 11.6), 3
(sections 3 and 11), 6,
19, 24
Applicable
Regulation No. 1102 sets forth the
permitting requirements for equipment
and construction activities that may
discharge air contaminants into the
atmosphere. Regulation No. 3,
sections 3 and 11, establish ambient
air quality standards for particulates.
Regulation No. 6 limits particulate
emissions from excavation/
construction operations. Regulation
No. 19 requires that odorous air
contaminants be controlled.
Regulation No. 24 requires the control
of emissions of the volatile organic
compounds.
Applicable to potential releases from
soil vapor extraction (SVE), soil gas
capture systems, excavation work, or
other remedial actions. If air stripper,
SVE, or soil gas system emissions
exceed 15 Ibs/day, the substantive
requirements of regulation No. 24 must
be met. In addition, the emissions must
meet the Ambient Air Quality Standards
set forth in Regulation No. 3. rjust
suppression measures must also be in
place to ensure that excavation and
construction activities meet the
regulatory requirements. Further, the
substantive requirements of Regulation
No. 1102 must be met.
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County,
Delaware
Table 2.2
On Facility Contaminants of Concern
and Preliminary Remediation Goals
for Standard Chlorine of Delaware Operable Unit 3
(Page 1 of 2)
1 ,4-Dichlorobenzene
Total Dichlorobenzene
Chlorobenzene
1,2,3 , 4-Tetrachlorobenzene
Total Tetrachlorobenzene
Pentachlorobenzene
Hexachlorobenzene
1 , 2 , 3-Trichlorobenzene
1,2, 4-Trichlorobenzene
Total Trichlorobenzene
2,3,7,8-TCDD
4,4 '-ODD
4,4'-DDT
20
20
40
10
10
20
7.01E-05
20
20
20
1.40E-05
4.94E-03
4.62E-03
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Earthworms
Robin NOAEL PRG
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Earthworms
Robin NOAEL PRG
Robin NOAEL PRG
Robin NOAEL PRG
Acenaphthene
Fluoranthene
Fluorene
Phenanthrene
Total Low Molecular Weight PAHs
20
0.19
30
0.21
29
ORNL Benchmark Concentration for Plants
Robin NOAEL PRG
ORNL Benchmark Concentration for Earthworms
Robin NOAEL PRG
Eco-SSLs for Terrestrial Invertebrates
Pyrene
Total High Molecular Weight PAHs
Pentachlorophenol
0.19
18.0
1.56E-04
Robin NOAEL PRG
Eco-SSLs for Terrestrial Invertebrates
Robin NOAEL PRG
Aluminum
Antimony
Beryllium
Chromium
Cobalt
Copper
Iron
Lead
Manganese
Mercury
Nickel
50
5
10
0.4
13
50
200
39.80
100
0.10
30
ORNL Benchmark Concentration for Plants
ORNL Benchmark Concentration for Plants
ORNL Benchmark Concentration for Plants
ORNL Benchmark Concentration for Earthworms
Eco-SSL for Plants
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Soil Microorganisms
and Microbial Processes
Robin NOAEL PRG
ORNL Benchmark Concentration for Soil Microorganisms
and Microbial Processes
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Plants
Standard Chlorine of Delaware Site Feasibility Study Report
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County,
Delaware
Table 2.2
On Facility Contaminants of Concern
and Preliminary Remediation Goals
for Standard Chlorine of Delaware Operable Unit 3
(Page 2 of 2)
Thallium
Vanadium
Zinc
1 ,4-Dichlorobenzene
Hexachlorobenzene
1,2,3, 4-Tetrachlorobenzene
1 ,2,4,5-Tetrachlorobenzene
2,3,7,8-TCDD
1.00
2.00
39.96
188.71
1.697
17
16
3.02E-05
ORNL Benchmark Concentration for Plants
ORNL Benchmark Concentration for Plants
Robin NOAEL PRG
Industrial Worker PRG
Industrial Worker PRG
Construction Worker PRG
Construction Worker PRG
Industrial Worker PRG
Benzene
1 ,4-Dichlorobenzene
Chlorobenzene
Carbon Tetrachloride
Chloroform
PCE
TCE
1 ,2-Dichlorobenzene
98
70
1400
26
20
60
4
21,600
Industrial Worker PRG
Industrial Worker PRG
Industrial Worker PRG
Industrial Worker PRG
Industrial Worker PRG
Industrial Worker PRG
Industrial Worker PRG
Industrial Worker PRG
mg/kg - milligrams per kilogram
ppbv - parts per billion by volume
NOAEL - No Observed Adverse Effect Level
ORNL - Oak Ridge National Laboratory
Eco-SSL - Ecological Soil Screening Level
(1) Summary of all human health and ecological receptors considered in the development of PRGs is included in Appendix A of this
document.
(2) Human Health PRGs were developed for trespasser, industrial worker, and construction worker receptors based on the 105 cumulative
target cancer risk and cumulative Target Hazard Quotient of 1 for non-carcinogens.
Standard Chlorine of Delaware Site Feasibility Study Report
U.S. EPA Region 3
HydroGeoLogic, Inc. July 2009
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County,
Delaware
Table 2.3
Off Facility Contaminants of Concern
and Preliminary Remediation Goals
for Standard Chlorine of Delaware Operable Unit 3
OFF-FACILITY TOTAL SOIL PRGs
Chemical
1 ,4-Dichlorobenzene
1 ,2,3 ,4-Tetrachlorobenzene
1,2, 4 ,5 -Tetrachlorobenzene
Hexachlorobenzene
2,3,7,8-TCDD
4,4 '-ODD
4,4'-DDT
Fluoranthene
Pentachlorophenol
Phenanthrene
Pyrene
Copper
Lead
Mercury
Zinc
PRG(1)
(mg/kg)
566
23
25
7.01E-05
1.40E-05
4.94E-03
4.62E-03
0.19
1.56E-04
0.21
0.19
235
39.8
0.20
40.0
Basis
Industrial Worker PRG(2)
Construction Worker PRG(2)
Construction Worker PRG(2)
Robin NOAEL PRG
Robin NOAEL PRG
Robin NOAEL PRG
Robin NOAEL PRG
Robin NOAEL PRG
Robin NOAEL PRG
Robin NOAEL PRG
Robin NOAEL PRG
Vole NOAEL PRG
Robin NOAEL PRG
Vole NOAEL PRG
Robin NOAEL PRG
OFF-FACILITY SOIL GAS PRGs
Chemical
1 ,4-Dichlorobenzene
Chlorobenzene
PRG(1)
(ppbv)
67
3200
Basis(2)
Industrial Worker PRG
Industrial Worker PRG
mg/kg - milligrams per kilogram
ppbv - parts per billion by volume
NOAEL - No Observed Adverse Effect Level
(1) Summary of all human health and ecological receptors considered in the development of PRGs is included in Appendix A of this
document.
<2) Human Health PRGs were developed for trespasser, industrial worker, and construction worker receptors based on the 105 cumulative target
cancer risk and cumulative Target Hazard Quotient of 1 for non-carcinogens.
Standard Chlorine of Delaware Site Feasibility Study Report
U.S. EPA Region 3
HydroGeoLogic, Inc. July 2009
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County,
Delaware
Table 2.4
Estimated Extent of Site Contamination
for Standard Chlorine of Delaware Operable Unit 3
Area of Concern
Soil PRO On-Facility Contamination
Added Volume for Soil Gas PRO On-
Facility Contamination
Off-specification product
PCB/dioxin concentration area
(RAS-1)
Catch basin #1 (RAS-2)
Former rail siding and loading area
(RAS-3/RAS-7)
Warehouse and the area to
the north of the warehouse (RAS-4)
Facility storm drains
Drum cleaning area (RAS-5)
Northern end of eastern drainage
ditch (RAS-6)
Former wastewater treatment plant
(RAS-8)
Chemical process area (RAS-
9/RAS-10)
1986 tank collapse area
Northeast tank farm
Total On-Facility Volume Exceeding
Soil/Soil Gas PRGs
22.8 Acres
2 to 12
351,060
10,000 sq. ft.
10,000 sq. ft.
65,000 sq. ft.
60,000 sq. ft.
5,000 sq. ft.
10,000 sq. ft.
10,000 sq. ft.
35,000 sq. ft.
50,000 sq. ft.
10,000 sq. ft.
65,000 sq. ft.
-
38(2)
38(2)
38(2)
38(2)
38(2)
38(2)
38(2)
38(2)
38(2)
38(2)
38(2)
-
14,100
14,100
91,500
84,450
7,050
14,100
14,100
49,250
70,400
14,100
91,500
815,710
Total "Northern Area" Volume
Exceeding Soil/Soil Gas PRGs (1)
1.4 Acres
50
111,000
NOTES:
(i)
The value provided here is a worst case scenario assuming the entire area west of the treatment building
would require remediation to address risks throughout the vadose zone. Although the Northern Area is part
of OU-3, it was separated for area and volume calculations because of the lack of data showing the presence
of contamination at levels requiring remediation. Contamination was found (drum remnants and chunks of
chlorobenzenes) in the northern end of the On Facility Area that is adjacent to the Northern Area. No
contaminants were detected at concentrations greater than the PRGs in the limited number of samples
collected from three locations in the Northern Area. Additionally, passive soil gas samplers deployed in the
Northern Area were relatively free of contamination when analyzed. Additional sampling data are needed to
further characterize this area.
Depth of soil to be addressed in addition to top 12 feet addressed for Soil PRGs.
Standard Chlorine of Delaware Site Feasibility Study Report
U.S. EPA Region 3
HydroGeoLogic, Inc. July 2009
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County,
Delaware
Table 2.5
Estimated Extent of Site Dioxin Contamination
for Standard Chlorine of Delaware Operable Unit 3
Volume of On-Facility Soil Exceeding
Dioxin Soil PRO
Off specification product
PCB/dioxin concentration area
(RAS-1)
Catch basin #1 (RAS-2)
Former rail siding and loading area
(RAS-3/RAS-7)
Warehouse and the area to
the north of the warehouse (RAS-4)
Facility storm drains
Drum cleaning area (RAS-5)
Northern end of eastern drainage
ditch (RAS-6)
Former wastewater treatment plant
(RAS-8)
Chemical process area (RAS-
9/RAS-10)
1986 tank collapse area
Northeast tank farm
Total On-Facility Volume Exceeding
Dioxin Soil PRO
10,000
10,000
65,000
60,000
5,000
10,000
10,000
35,000
50,000
10,000
65,000
7.6 Acres
12
12
12
12
12
12
12
12
12
12
12
-
4,450
4,450
28,900
26,700
2,200
4,450
4,450
15,550
22,200
4,450
28,900
146,700
Total "Northern Area" Volume
Exceeding Dioxin Soil PRG(1)
1.4 Acres
12
26,700
(1) The value provided here is a worst case scenario assuming the entire area west of the treatment building
would require remediation to address dioxin risks. Although the Northern Area is part of OU-3, it was
separated for area and volume calculations because of the lack of data showing the presence of contamination
at levels requiring remediation. Contamination was found (drum remnants and chunks of chlorobenzenes) in
the northern end of the On Facility Area that is adjacent to the Northern Area. No contaminants were
detected at concentrations greater than the PRGs in the limited number of samples collected from three
locations in the Northern Area. Additional sampling data are needed to further characterize this area.
Standard Chlorine of Delaware Site Feasibility Study Report
U.S. EPA Region 3
HydroGeoLogic, Inc. July 2009
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FIGURES
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County,
Delaware
3.0 IDENTIFICATION AND SCREENING OF TECHNOLOGY TYPES
AND PROCESS OPTIONS
General Response Actions (GRAs), and specific technology types and Technology Process
Options (TPOs) within each general response action type are defined in this section. The
phrase "technology process options" refers to specific processes within each of the general
technology types. For example, TPOs within the "treatment" GRA include chemical oxidation
and soil washing.
GRAs are introduced in Section 3.1. In Section 3.2, potential remedial technologies are
identified within each of the General Response Actions. The identified TPOs are first pre-
screened based on technical feasibility at OU-3. The results of the pre-screening analysis are
summarized in Table 3.1. In Section 3.3, TPOs retained from the initial pre-screening are
screened again based on effectiveness, implementability and cost. The TPOs that remain after
the screening are summarized in Section 3.4. These remaining TPOs will be used in
assembling remedial alternatives for OU-3.
3.1 GENERAL RESPONSE ACTIONS
GRAs are medium-specific generic types of remedial actions that can, alone or in combination,
achieve the established RAOs for the site. GRAs proposed for the site include the following:
• No Action. No action GRA implies that the site is left in its present condition. This
response action provides a background against which all other remedies can be
compared. A no action alternative is required for consideration by the NCP.
• Institutional Controls. ICs may reduce human health risks from site contaminants by
restricting land use or activities at the site. ICs will not reduce ecological risks.
• Containment. Containment refers to physical processes that would restrict
contaminant mobility without changing their concentration or toxicity. Containment
protects human health and minimizes ecological risk by controlling the routes of
exposure.
• Treatment. Treatment may include any physical, chemical or biological processes that
would lower human health or ecological risk from the contaminants by their destruction
or conversion into less hazardous forms.
• Removal. Removal includes physically removing contaminated soils as an initial step
for treatment and/or disposal.
• Disposal. Disposal involves methods to discard the treatment by-product or removed
soils off site in accordance with all applicable regulations.
• Monitoring. Monitoring of site conditions provides useful information about
remediation progress. In addition to visual inspection of installed RA measures,
monitoring also includes sampling of soil, sediments, soil gas, groundwater, and
surface water.
Applicable technologies associated with each of the above GRAs are discussed below. These
technologies are typical of sites with nature and extent of contamination similar to OU-3.
U.S. EPA Region 3
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3.2 IDENTIFICATION AND SCREENING OF POTENTIALLY APPLICABLE
TECHNOLOGIES
A range of technology types and process options was identified and pre-screened according to
their overall applicability to the primary contaminants and conditions present at the site. For
each GRA, one or more technology types and associated TPOs were identified. The initial
screening results are summarized in Table 3.1. Some of the sources consulted during the
identification of technologies include reference documents published by the EPA, feasibility
studies for similar sites, standard engineering texts, and professional experience. Each
technology is described in more detail in Section 3.3.
3.3 EVALUATION OF POTENTIAL REMEDIAL TECHNOLOGIES
In this subsection, each of the technologies listed in Table 3.1 is described in further detail.
For those technologies identified in the preliminary screening as not potentially effective, the
rationale for this decision is included. Those technologies that have been identified as
potentially effective are evaluated in greater detail based on their effectiveness,
implementability and cost. Based on this evaluation, the technology is either retained for
further evaluation or eliminated. Each of the three criteria is briefly defined below:
• Effectiveness - The ability of a technology to meet defined RAOs for protection of
human health and the environment.
• Implementability - Technical and administrative feasibility of implementing the
technology. TPOs that are not technically feasible at the site were eliminated during a
pre-screening step. During this evaluation, the remaining TPOs are compared based on
such considerations as the ability to meet the substantive provisions of permit
requirements, the availability of treatment, storage, and disposal services, and the
availability of necessary equipment and skilled workers to implement the technology.
• Cost - A relative estimate of the cost of implementing the technology. This is based on
engineering judgment and available reference sources. Costs are given as very low,
low, moderate, or high relative to other process options.
Table 3.2 summarizes the results of this evaluation for those technologies that were carried
forward from the pre-screening.
3.3.1 No Action
Description-The no-action option consists of leaving the site as it is, without any remediation
activities.
Effectiveness-This response does not meet the RAOs and would not be protective of human
health or the environment.
Implementability-No actions are required to implement this option, but is not likely to be
approved by the public.
U.S. EPA Region 3
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Cost-No costs are associated with this option.
Recommendation-The NCP requires that the no action alternative be used as a baseline
against which to compare remedial technologies. Therefore, the No Action option was
retained for further analysis.
3.3.2 Institutional Controls
Institutional controls are actions, such as legal controls, that help minimize the potential for
human exposure to contamination by ensuring appropriate land or resource use. Although it is
EPA's expectation that treatment or engineering controls will be used to address principle
threat wastes and that groundwater will be returned to its beneficial use whenever practicable,
ICs can and do play an important role in remedies. ICs do not reduce contaminant toxicity,
mobility, or mass. They do reduce or eliminate the potential for human exposure and can help
protect existing and future remedial measures.
All of the proposed remedial alternatives include ICs in combination with other treatment or
containment methods. Therefore, the ICs were retained for further analysis. The proposed
ICs include proprietary controls such as restrictive covenants and access agreements,
governmental controls such as a Groundwater Management Zone, and informational devices
such as public information/awareness programs.
With regard to the SCD Site, it is expected that ICs will be used to achieve the following
goals:
• Prevent residential or other incompatible land use - Eliminating the potential for
residential land use will help reduce the potential exposure that a person (or people)
could have to site contaminants by limiting the amount of time that they spend on the
site in any one day. The PRGs that were developed for the OU-3 portion of the site
were not based on residential factors, and therefore the possibility of future residential
use must be eliminated to ensure that future potential exposure levels match those
envisioned in the development of the PRGs. Similarly, incompatible uses such as a
children's day care center must be prevented to restrict the potential exposure of those
most vulnerable to any potential residual hazards from the site. This goal could be
accomplished through the use of a proprietary control such as a restrictive covenant.
• Prevent heavy industrial site use - To meet the requirements the Delaware Coastal
Zone Act, no heavy industrial operations may be situated on the site in the future.
Eliminating the potential for heavy industry will be accomplished via government
controls (i.e., the Coastal Zone Act itself) and proprietary controls such as a restrictive
covenant.
• Prevent use of site groundwater - Because of the contamination located in the
subsurface soils and the groundwater underlying the site, it is imperative that no one be
allowed to drink groundwater recovered from the site. This goal would be achieved
through a government control (i.e., Groundwater Management Zone).
• Require vapor intrusion protection measures in any building built at the site - Because
human health risks from soil vapor at the site are primarily through the indoor exposure
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pathway (Black & Veatch, 2007), restrictive covenants may be implemented to require
that future on site buildings be equipped with vapor intrusion control features (e.g.,
passive barriers, passive or active venting, and subslab pressurization).
• Ensure that installed remedial measures remain in good working condition - It will be
necessary to inspect, monitor, operate, and maintain OU-3 remedial measures as well
as already existing measures [e.g., GETS, containment barrier, and the temporary soil
staging area (TSSA)]. EPA and/or DNREC representatives will also need to have
access to effect repairs and conduct site monitoring activities. These goals would be
achieved through the use of proprietary controls including restrictive covenants and
access agreements.
• Prevent or restrict activities that would damage installed remedial measures or cause
excessive exposure to site contaminants - Certain types of activities (including
excavation of site soils) will have to be prevented or restricted to prevent damage to
existing remedial measures (i.e., GETS, containment barrier, and the TSSA).
Similarly, excavation of deeper soils will need to be prevented to reduce the potential
for worker exposure. These goals would be achieved through the use of proprietary
controls including restrictive covenants.
• Inform the public about site developments and warn people about site hazards - It is
important to keep the public informed about site developments to prevent
misunderstandings and to improve public perceptions about site activities. Public
meetings and informational brochures can be used along with warning signs to ensure
that these goals are met.
3.3.3 Containment
Containment involves installation of physical barriers to prevent further migration of
contaminants from the soil and to eliminate the routes of exposure to humans and ecological
receptors. Containment TPOs considered in this FS Report include horizontal surface barriers
(caps) and subsurface barriers.
3.3.3.1 Security Fencing
Description-The site has a chain link security fence around the perimeter of the former facility
area. This option would involve maintenance of the fence, possible elimination of some access
gates, and replacement of sections that are in need of repair.
Effectiveness-The security fence does limit access to the site, but there have been
unauthorized entries made to the site by cutting the locks on one or more gates. A reduction in
the number of gates might reduce the ability of unauthorized personnel to gain access. The
security fence does not reduce environmental risks or the toxicity, mobility or volume of the
site contaminants.
Implementability - The security fencing is already in place. Maintenance of the fence would
be easily implemented. Depending on the eventual use of the site, the security fence could be
seen as an aid or an impediment to future development.
U.S. EPA Region 3
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Cost-The cost of security fencing at the site would be very low to low.
Recommendation-Security fencing was retained for further consideration in combination with
other remedial options.
3.3.3.2 Surface Horizontal Barriers (Caps)
Construction of a surface horizontal barrier on the site can potentially achieve multiple RAOs:
• Minimize human and wildlife exposure to contaminants in the surface soil and soil gas
• Prevent spread of contaminants via air-blown soil particles, surface runoff, or seepage
into groundwater;
• Minimize escape of the soil gases into the atmosphere;
• Prevent or substantially reduce infiltration of stormwater into contaminated subsurface
soils;
• Serve as a temporary control to contain waste while treatment is being applied.
Any surface cap design for the site would need to be equipped with a gas collection and
treatment system. Tying the surface cap into the previously constructed vertical groundwater
containment barrier should be considered where practical to improve remedy performance.
Care must be taken during construction activities to avoid damaging the previously installed
containment barrier and GETS. To provide a stable foundation for the cap construction,
subsurface structures (such as catchment basins, storm drains, process piping, and abandoned
utilities) will need to be removed along with concrete containment pads, tanks, and other
demolition debris. Additionally, the potable water supply to the GETS building should be
relocated to avoid possible damage to the cap and allow easier access for maintenance of the
water line. If capping is subsequently considered in offsite areas to the east of the SCD fence
line, some mature vegetation will need to be removed.
It is possible that some soil will need to be removed as part of the cap construction process.
Because the removed materials would contain contaminants above acceptable risk levels, these
excavated soils would need to be treated or disposed of as hazardous waste, unless they can be
placed back in the area being capped.
Types of surface caps that are being considered include evapotranspiration (ET), soil/clay,
chemical sealant, multilayer, concrete, and asphalt. Regardless of the type of cap selected, the
design must include an associated stormwater control so that the cap can be naturally integrated
into the adjacent ecosystems. The effectiveness, implementability, and cost of the different cap
types, as well as the findings of the TPO screening process are summarized below:
Evapotranspiration Cap
This TPO was eliminated in the pre-screening stage. ET caps use vegetative cover to reduce
the infiltration of precipitation into contaminated soils. This type of cover has gained
popularity in recent years as a low cost alternative to traditional cap construction methods
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because of its low cost of construction and reduced maintenance requirements. It is
particularly appropriate in more arid climates where a lack of moisture can cause cracking and
failure of traditional clay liners (AFCEE, 1999). Unfortunately, ET caps would not effectively
eliminate the soil gas exposure pathway at OU-3 unless a vapor barrier were integrated into the
design, and the precipitation rate in the area (approximately 43 inches/year) would likely be
too high for such a cap to function properly. The required vapor barrier would likely worsen
the performance of the ET cap in this high precipitation area. For these reasons, this TPO was
removed from further consideration during the pre-screening stage.
Soil and Clay-Based Caps
Description-Soil and clay-based caps are single layer caps that use low permeability soil or
clay to reduce or stop infiltration of precipitation.
Effectiveness-Single layer soil and clay-based caps could potentially achieve RAOs for the
OU-3 soil and soil gas, provided sufficiently low permeability material is used to prevent
infiltration. Although it would be somewhat easier to reseal a cap of this type as opposed to a
multilayer cap in the event of a breach (as part of future construction activities), substantial
effort would still be required to ensure that the disturbed areas did not result in increased soil
and/or soil gas exposure.
Implementability-Single layer soil or clay-based cap can be relatively easily constructed at
OU-3 using standard construction equipment and procedures. This type of cap often requires
more maintenance than asphalt or concrete caps because it is more susceptible to erosion and
cracking from freezing and thawing. Although warm season grasses might reduce maintenance
costs for this type of cap, the a soil or clay cap would still be more likely than an asphalt or
concrete cap to have structural failure because of erosion, cracking, or burrowing animals.
Because damage to monitoring wells and piezometers is possible during cap construction,
replacement or modification of these features might be required.
Cost - The cost of this TPO would be relatively low to moderate.
Recommendation-Because of the increased potential for failure relative to other types of caps,
single layer soil/clay caps were eliminated from further consideration during the screening and
evaluation stage.
Chemical Sealant Cap
Chemical sealant caps were eliminated from further consideration during the pre-screening
stage (Table 3.1). A chemical sealant cap uses native soil mixed with some form of binding
agent (cement, lime, grout) to reduce the soil permeability. Because contamination exists in
much of the surface soil and shallow subsurface soil across the area of consideration, the use of
native soils in cap construction is not feasible. Consequently, chemical sealant caps were not
retained for further consideration.
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Multi-Layer Cap
Description-A multilayer surface cap, such as a RCRA Subtitle C cap, is appropriate for
hazardous waste applications. This type of cap generally includes an upper vegetative (topsoil)
layer, a drainage layer, a synthetic membrane, and a low permeability barrier layer placed
over a foundation layer of sand or native soils. The barrier layer can be constructed with low-
permeability soil (clay) and/or geosynthetic clay liners. RCRA Subtitle C caps are typically
six foot or more in thickness (AFCEE, 1999).
Effectiveness-A multilayer surface cap could potentially achieve RAOs at OU-3 by limiting
contact with contaminated soil and soil gas, reducing infiltration and limiting contaminant
mobility. By limiting infiltration, a multilayer cap would greatly reduce the potential for
contaminants to spread via the soil to groundwater pathway. Multilayer soil caps tend to be
more effective than simple soil covers. It would be relatively difficult to reseal a multilayer
cap if it were to be breached for future construction of a building, additional extraction wells,
DNAPL removal wells, or monitoring wells.
Implementability-A multilayer surface cap can be implemented relatively easily at OU-3
using readily available technology and materials. This technology is harder to implement than
other surface soil cap types. To be used at OU-3, demolition debris and possibly a substantial
quantity of soil would have to be removed to prepare the site for installation of a multilayer
cap. Additionally, features such as the GETS piping, extraction well vaults, monitoring wells,
piezometers, and the asphalt access road might need to be raised, reconstructed, or otherwise
modified to make the implementation of a multilayer cap feasible. Maintenance of a multilayer
cap would include erosion repair, vegetation trimming, and possibly animal control/removal.
Cost - Low to Moderate: unit costs of between $500,000 and $650,000 per acre are typical for
surface cap construction. Well repair/replacement costs would be added to these figures as well
as disposal costs for the demolition debris that would have to be removed (or possibly crushed)
to provide an acceptable base for cap construction.
The costs associated with the multilayer surface cap are low to moderate, although they are
expected to be somewhat higher than the cost of other surface cap alternatives.
Recommendation-This approach was retained for further analysis.
Asphalt or Concrete Cap
Description-Asphalt and concrete caps consist of an asphalt or concrete layer over the
contaminated soils, designed to minimize contact with soil and soil gas and limit infiltration of
stormwater.
Effectiveness-Concrete and asphalt caps can effectively control erosion, reduce soil gas
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exposure, and minimize precipitation infiltration. These caps are more resistant to erosion and
require less maintenance than soil and multilayer caps (AFCEE, 1999). By limiting
infiltration, an asphalt or concrete cap would greatly reduce the potential for contaminants to
spread via the soil to groundwater pathway. It would be relatively simple to reseal a concrete
or asphalt cap if it were to be breached for future construction of a building, additional
extraction wells, DNAPL removal wells, or monitoring wells.
Implementability-Concrete or asphalt caps can be easily implemented at OU-3. Maintenance
of these caps typically involves the periodic application of sealers and repair of cracks. The
appearance of these caps can be considered a draw-back, but because they are fairly thin (less
than one foot thick in general) they could be installed relatively quickly, would require less soil
removal than a multi-layer cap, and would be less likely to require modification of the
previously installed IGR features. Because damage to monitoring wells and piezometers is
possible during cap construction, replacement or modification of these features might be
required.
Cost - Low to Moderate: unit costs of between $300,000 and $550,000 per acre are typical
for surface cap construction. Reapplication of sealants and well repairs/replacements would be
added to these figures as well as disposal costs for the demolition debris that would have to be
removed (or possibly crushed) to provide an acceptable base for cap construction.
Recommendation-This treatment option was retained for further consideration.
3.3.3.3 Subsurface Horizontal Barrier
The subsurface horizontal barrier alternative was eliminated from further consideration at the
pre-screening stage. In this treatment option, a horizontal impermeable barrier is installed
within the subsurface. Several of the available subsurface barrier installation technologies, such
as high pressure jet grouting and deep soil mixing, can be used to avoid the excavation of
surface soils.
This technology would be an attractive option for locations where the main contamination of
concern is limited to subsurface soils. As this is not the case for the SCD site, surface soils in
areas with contamination exceeding the developed PRO concentrations would still need to be
excavated or treated. Additionally, stormwater that collects above the subsurface barrier would
have to be collected. Collected water would need to be treated until the surface soil is free of
contamination. In addition, the extent of the contamination present at OU-3 might make it
difficult to ensure continuity and integrity of the subsurface barrier across the site.
3.3.4 Treatment
Soil treatment methods can be subdivided into two general categories: in situ and ex situ. Ex
situ methods involve excavation of the soil before treatment, while in situ treatment is
performed in place. In situ and ex situ treatment methods can rely on chemical, physical, or
biological processes, as well as combinations of these. All ex situ treatment considerations
must take into account the costs for excavation and, for some alternatives, transportation of
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soils.
Ex situ processes that were considered for use in conjunction with some other remedial
alternative include ex situ chemical oxidation, thermal destruction (incineration), low
temperature thermal desorption (LTTD), soil washing, in-vessel bioremediation, and biopiles.
In situ processes considered for the site include in situ chemical oxidation (ISCO), soil vapor
extraction (SVE), soil flushing, in situ thermal desorption (ISTD), and enhanced
bioremediation. These processes are evaluated below.
3.3.4.1 Chemical Oxidation
Chemical oxidation typically involves the introduction of an oxidant via injection or soil mixing
into contaminated soil or water to initiate a reduction/oxidation (redox) reaction. This redox
reaction can chemically convert hazardous contaminants to nonhazardous or less toxic
compounds and elements through the transfer of electrons from the contaminant to the oxidant.
As a result, the organic contaminant is broken down, with water, carbon dioxide, chlorine (in
the case of chlorinated compounds), and other relatively nontoxic chemicals as the end
products of the reaction.
Contaminants that are present on the site and could be treatable with ISCO include benzene,
chlorinated benzenes, chlorinated solvents (TCE and PCE), carbon tetrachloride, and
chloroform. It has also been suggested that PCBs, PAHs, dioxins, organic pesticides, and
phenols could also be treated using this technology (ITRC, 2005). Further site characterization
would be needed to identify the best locations for oxidant applications (through either
injections or mixing) and determine dosing requirements.
The primary benefits to the chemical oxidation approach are its fairly quick treatment time and
the fact that the contaminants are destroyed. Potential drawbacks for this technology include:
• Mobilization of metals as a result of change in pH and/or oxidation states;
• Volatilization of organic chemicals due to the exothermic nature of the reactions;
• Potential difficulty delivering and effectively distributing the treatment chemicals to all
of the contaminated areas;
• Potential regulatory issues associated with underground injection control (UIC) and air
quality impacts from off-gassing; and
• Potential chemical or temperature effects on the newly constructed containment barrier.
(The area where the heaviest soil contamination was identified in the RI is along the
former rail siding.)
When determining the costs and feasibility of employing oxidation for a particular case,
various parameters must be taken into account including:
• Kinetic rate of reaction
• Unit cost of oxidant
• Application method requirements
• Hazardous material handling requirements
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• Required quantity of the oxidant
• Site geology and hydrogeology
• Soil pH
• Abundance of naturally occurring organic matter
• Mass of contaminants sorbed to site soils
• Accessibility to the contaminated area
In-Situ Chemical Oxidation
Description-For ISCO, oxidants are injected into the subsurface as a solution (or in the case of
ozone as a gas) or mixed into the soil as a solid or a liquid, although ozone can also be injected
as a gas. In some cases co-amendments (such as iron in Fenton's reagent reactions) are added
to optimize the reaction.
Effectiveness-ISCO can potentially treat most of the organic contamination present at the site,
but it would not likely reduce the toxicity of most metals contamination. Because of the
potential for the exothermic reactions to harm the existing containment barrier, it would not be
possible to apply this technology near the barrier. Thus, this approach would not address some
of the heavily contaminated soils located in the former rail siding area. Additionally, the
oxidation process and the introduction of liquids into the vadose zone could mobilize site
contaminants and allow them to further contaminate the underlying groundwater.
Implementability-Further site characterization would be needed to identify the best locations
for oxidant applications (through either injections or mixing), to select the oxidant, and to
determine dosing requirements. A bench-scale treatability study showed that Fenton's reagent
(hydrogen peroxide mixed with acidified iron) successfully reduced chlorobenzene
concentrations in facility soils by an average of more than 90 percent. It would be difficult to
distribute the oxidant throughout the vadose zone across the areas with contaminant
concentrations greater than the PRGs. Pilot-scale studies would be needed to determine
whether a full-scale chemical oxidation approach could cost-effectively treat the contaminated
soils in question. Oxidants should not be injected or mixed into soil near the groundwater
containment barrier because they could alter chemical properties of the barrier and possibly
increase its permeability. Another potential problem is that the oxidant injections could create
high pressure pathways that could penetrate the barrier. Soil mixing in the area of the
containment barrier would alter the mechanical properties of the soil and possibly undermine
the barrier's structural integrity. Oxidation of chlorinated compounds would increase chloride
concentrations in the subsurface. Elevated chloride concentrations could attack GETS
components as well as the containment barrier.
Cost - Moderate to High: Costs for ISCO are highly variable depending on site and
contaminant characteristics, but estimates of $30 - $100 per cubic yard of soil have been
reported (ITRC, 2005).
Recommendation-Because of the inability to treat the highly contaminated soils adjacent to the
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containment barrier, and the inability to meet PRGs for metals, ISCO was retained for
consideration only in combination with other technologies. For example, ISCO could be used
to treat certain hot spots that are not located close to the containment barrier.
Ex-Situ Chemical Oxidation
Description-For ex situ applications of chemical oxidation, the contaminated soils are
excavated and placed in a lined containment area before the oxidants are mixed in.
Effectiveness-Ex situ chemical oxidation could effectively treat organic contaminants in site
soils. The technology could be used to treat soils that have been excavated during the
construction of a surface cap.
Implementability-Construction of a suitable containment structure equipped with leachate and
gas collection and treatment systems would be expensive and would require substantial open
area. Treatability studies would be needed to determine whether oxidation would effectively
treat PCBs, PAHs, pesticides, and dioxin. Excavation of soils to the 50 foot depth required to
address soil gas risks would be very difficult and expensive. Additionally, off site disposal of
the treated soil might be required if sufficient on site disposal areas cannot be identified or if
PRGs cannot be met.
Cost - High: Construction costs combined with the excavation costs and those of the large
quantity of oxidant that would be required to ensure destruction of the contaminants would
likely make this option somewhat cost-prohibitive, with estimated costs ranging from $150 to
$500 per cubic yard (FRTR, 2002).
Recommendation-Because of the space requirements, high implementation costs, difficulties
related to excavation of deeper contaminated soils, and lack of metals treatment, ex situ
chemical oxidation was eliminated from further consideration during the screening and
evaluation stage.
3.3.4.2 Soil Vapor Extraction
Description-SVE involves the application of vacuum to contaminated soils to extract volatile
and some semivolatile organic compounds in a gaseous form. To ensure that the vacuum is
applied to all of the contamination above the groundwater table, vacuum wells should be
installed and screened across the entire vadose zone below the cap. Well placement and
blower sizing should be selected to ensure that the radii of influence overlap and address the
entirety of the contaminated area.
The extracted gas is typically treated using a condenser, vapor phase GAC, a thermal oxidizer,
or a catalytic oxidizer before it is released into the atmosphere. It is best suited for well
drained, high-permeability soil (sand and gravel) with low organic carbon content (EPA,
2006). In soils with heterogeneous properties (such as varying water content or permeability)
short-circuiting might lead to poor treatment in the regions with less permeable or water logged
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soils. In addition, organic contaminants in soils that are too dry or have substantial natural
organic matter will adsorb more strongly to the soil, and therefore increase difficulty of their
removal.
Effectiveness-SVE has been used to treat many of the contaminants present on the site.
However, SVE would have limited effectiveness on or would be ineffective in treating
pesticides, PCBs, dioxins, and most SVOCs and metals. An SVE system would likely need to
be operated for at least one to two years for effective reduction of soil and soil gas risks from
those contaminants that would be amenable to treatment.
Implementability-SVE is a well established technology for Superfund sites. The vadose zone
soils at the SCD site are sandy with permeabilities in the range of 10~3 to 10~2 cm/sec. This
type of soil is generally well-suited to treatment with SVE. SVE performance can be enhanced
by covering the soil surface with a low permeability layer (such as concrete, asphalt, or a
geomembrane) to prevent short-circuiting of the air flow and to increase the radius of influence
of the extraction wells (FRTR, 2002). Consequently, combining an SVE system with a surface
cap could enhance both remedial options. Additionally, the blowers and off-gas treatment for
an SVE system could be utilized for a surface cap's gas collection system. Any media used for
the vapor treatment (e.g. activated carbon) would have to be regenerated or disposed of as
hazardous waste, and the substantive provisions of air discharge permit requirements would
most likely need to be met. Pilot-scale treatability studies would be needed to confirm potential
effectiveness and provide guidance for determining well spacing. Further site characterization
would assist in optimizing SVE well placement.
Cost - Low to High: Cost estimates for unheated in situ SVE vary widely with ranges from
$30 to $110 per cubic yard cited for sites involving the treatment of 5,000 to 50,000 cubic
yards of soil and costs as low as $2 to $3 per cubic yard achieved for sites involving over
100,000 cubic yards of contaminated soil (EPA, 2001). Although large volumes of soil would
require treatment at the SCD Site, the recalcitrant nature of certain site contaminants and the
depth over which contamination extends indicate that unit costs for OU-3 would probably be in
between these figures (in the $5 to $15 per cubic yard range).
Recommendation-Because the bulk of the site contaminants are VOCs, SVE could be used to
reduce contaminant levels in certain hot spot areas. SVE would not be suitable as a stand-
alone, site wide treatment because it fails to address dioxins, metals, pesticides, and most
SVOCs. SVE was retained as an option for use in conjunction with other treatment and
containment alternatives.
3.3.4.3 In Situ Soil Flushing
Description-Soil flushing involves flooding contaminated soil with water or a solution to
mobilize contaminants. The water or liquid solution is injected or infiltrated into the area of
contamination. The contaminants leach into the water/solution, which is then recovered and
treated before being re-injected or discharged.
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Effectiveness-Even though some of the site contaminants may be amenable to soil flushing, it
is unlikely that a single wash fluid would be able to remove all COCs due to their diverse
physico-chemical characteristics. Thus, application of multiple flush solutions would likely be
required. To be effective, it is necessary for the flush solution to be distributed throughout the
entire treatment zone. The potential for the injected fluid to short-circuit the contaminated
soil, particularly if it is necessary to inject multiple solutions, decreases the effectiveness of
this TPO. Additionally, soil flushing would mobilize many of the contaminants in question
allowing those contaminants that are not recovered to further impact the groundwater.
Implementability-In situ flushing is well-suited to treatment of contaminants in sandy soils,
but the depth of groundwater in the treatment area (between 40 and 50 ft bgs) would make
treatment with this technology more difficult and would require greater volumes of liquid
injection. With the large area requiring treatment, it would be difficult to install a fluid
injection/capture system that would allow treatment of the entire soil volume while ensuring
that the wash solution and mobilized contaminants are captured before they reach the
groundwater. The greater liquid injection volume would have the effect of increasing the
groundwater elevation and instill/increase a downward gradient between the Columbia and
Potomac aquifers. This would increase the likelihood of spreading site contaminants to the
Potomac and increase the operational costs of the GETS.
Cost - High: Published costs for large scale projects using soil flushing range from $65 to
$200 per cubic yard of treated soil (ITRC, 2003).
Recommendation-In situ soil flushing was eliminated from further consideration during the
screening and evaluation stage because of its potential to drive additional contamination into
the Potomac Aquifer.
3.3.4.4 Ex Situ Soil Washing
Description-Ex situ soil washing applies the soil flushing concept to excavated soils.
Effectiveness-Ex situ soil washing would eliminate the concerns over the potential for
increased contamination of the Columbia and Potomac Aquifers associated with the in situ
flushing technique. Because of the large volume of soils that would require treatment and their
sandy nature, it is possible that these soils would likely require disposal in an off-site landfill.
Implementability-This treatment process would require a large area for implementation. The
complex mixtures of contaminants (VOCs, SVOCs, PCBs, pesticides, dioxins, metals) found at
the site would require sequential washing steps, using different wash formulations and/or
different soil-to-wash-fluid ratios. Treatability studies would be required to determine what
combination of washing steps and solutions would be needed to treat the site soils.
Additionally, because this technology only separates the contamination from the soil, the
recently built GETS would need to be expanded, a separate treatment system constructed, or
the generated wastewater would have to be transported to an off-site disposal facility.
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Cost - Moderate to High: Costs for this technology have been reported to range between
approximately $50 and $200 per cubic yard (FRTR, 2002; ITRC, 1997), but the nature of the
wastes at the site and the possibility that the treated wastes will need to be disposed off site
would push the costs of implementation to (or possibly above) the high end of this range.
Recommendation-Because of the complexity of the technology, space requirements, and the
potential disruption to the existing GETS, ex situ soil washing was retained for possible use
with only excavated materials resulting from cap construction.
3.3.4.5 In Situ Thermal Desorption (ISTD)
Description-During ISTD, the soil is heated to temperatures above the boiling points of the
contaminants (in the range of 500 to 650°F for most chlorobenzenes), enhancing volatilization
of adsorbed VOCs and SVOCs. Higher temperatures can be utilized to address PCB,
pesticide, or dioxin contamination if necessary. Heating of the soil in ISTD can be achieved
by several methods, including hot air or steam injection, radio-frequency heating (RFH),
electrical resistance (ER) heating, and thermal conduction heating. Any volatilized compounds
are typically removed using an SVE system. Off-gas is treated (typically using carbon
adsorption or thermal oxidation) before discharge. Alternatively, a condenser can be used to
separate the contaminants from the air stream and capture them for reuse or disposal as a
liquid. This combination of SVE and ISTD, sometimes referred to as thermally enhanced
SVE, is a relatively well established technology that can achieve remediation of a wider range
of organic contamination in a shorter time frame than SVE alone.
Effectiveness-Most, if not all, of the organic contaminants in the soil at SCO can be treated by
ISTD. Unfortunately, this technology would not adequately address most metals contamination
in the soils, but a mercury capture system would be required as part of the off-gas treatment
train. While the heating of the soil would increase the mobility of organic contaminants, the
vacuum that is developed by the systems extraction wells would pull the volatilized
contaminants away from the groundwater and recover them, minimizing the potential for
contaminant migration to groundwater during process implementation.
Implementability-If used near the soil bentonite containment barrier, the heat generated by
ISTD during the treatment of site soils would likely have an adverse impact on the long-term
performance of the barrier. For this reason, ISTD should not be used in close proximity to the
containment barrier, but the technology could be used to treat other hot spots. According to
information provided by one vendor, the "heat front" from ISTD dissipates within
approximately 7 ft of the heated zone (TerraTherm, 2007). To protect the containment barrier
from damage, the heat zone should be kept a minimum of 10 ft from the barrier. To ensure at
least partial treatment of soils near the containment barrier, unheated SVE wells could be used
in that area. Because of the need to place heat sources in relatively close proximity to each
other, additional site characterization would help optimize treatment and reduce operational
costs.
Cost - Moderate to High: Literature sources list approximate costs for treating site soils using
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ISTD in the range of $40 to $130 per cubic yard of soil (FRTR, 2002; P2Pays, 1998).
Budgetary estimates obtained in conversations with TerraTherm indicate that costs treatment of
soil contamination of the type found at SCD would be in the range of $125 to $175 per cubic
yard, with treatment of dioxin contaminated soils costing approximately $200/cubic yard.
Recommendation-Because ISTD's expense and the fact that it cannot be used near the soil
bentonite containment barrier, the technology was retained for use only in combination with
other technologies, such as unenhanced SVE.
3.3.4.6 Ex Situ Low Temperature Thermal Desorption (LTTD)
Description-Ex situ LTTD can be used to remove VOCs and some SVOCs from excavated
soils. It operates using the same principles as in situ LTTD described earlier: soil is heated to
volatilize organic contaminants, and a carrier gas or vacuum system transports volatilized
water and organics to the gas treatment system.
Effectiveness-Thermal desorbers with temperatures in the range of 200 to 600°F are able to
achieve 95 percent contaminant destruction efficiency for treating VOCs and SVOCs while the
decontaminated soils retain their physical properties. Thermal desorbers with temperatures in
the thermal range 600 to 1,000°F can produce final contaminant concentrations below 5 mg/kg
and are effective for treating PAHs, PCBs, pesticides, SVOCs, and VOCs. LTTD would not
address the bulk of metals contamination at the site and would require the use of a mercury
capture system.
Implementability-The ex situ process has benefits of providing a more controlled
environment, and ensuring consistent treatment. However, it is a more intrusive and costly
alternative, with high associated excavation and equipment costs.
Cost - Moderate to High: Based on vendor information gathered for the Soil/Sediment Design
Comparison Study, unit costs of between $104 and $195 per cubic yard can be expected (Black
& Veatch, 2003). These costs are in line with those listed in the FRTR for this technology
(FRTR, 2002). It is likely that recent increases in fuel costs would result in higher treatment
costs than those listed here.
Recommendation-Ex situ LTTD was retained as a possible treatment option for excavated
soils removed in the process of surface cap construction.
3.3.4.7 Ex Situ Thermal Destruction (Incineration)
Description-During the incineration process, the soils are heated above the combustion
temperature of most organic contaminants (1,600 to 2,200°F) in the presence of oxygen.
Available incineration processes include rotary kiln, fluidized-bed, and infrared options.
Effectiveness-High temperatures employed during the incineration process result in the
destruction of most organic compounds, with treatment efficiencies commonly exceeding 99.99
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percent. Generated off gases and combustion residuals generally require treatment.
Implementability-Mobile incinerator units are commercially available, but it is doubtful that
an incinerator would be granted the necessary permits to operate in the coastal zone. Off-site
incineration is possible, but transportation of the quantities of soil requiring remediation over
the distances to the closest acceptable incinerator would increase the potential to spread site
contamination, and would substantially increase cost. Given the history of the site, this
approach would probably not be viewed favorably by the local citizenry. Other regulatory
concerns associated with incineration include generation of toxic air pollutants and disposal of
ash residue. An incineration facility must submit to a full-scale evaluation, including a trial
burn monitored by regulatory agencies, to demonstrate its ability to meet performance criteria
for various materials. Separately, the soils in question would have relatively low energy
content and could require substantial additional fuel for incineration.
Cost - High: Incineration is a very expensive process with costs ranging from approximately
$585 to $1,171 per cubic yard of soil (FRTR, 2002; Black & Veatch, 2003). The large volume
of soil from OU-3 that would require treatment might push costs toward the lower end of this
range, although recent increases in fuel costs might result in higher costs.
Recommendation-Considering the high costs, off site ex situ incineration was retained for
possible treatment of small quantities of excavated soils with contaminants that are not suitable
for other forms of treatment (such as dioxins and PCBs).
3.3.4.8 In Situ Enhanced Bioremediation
Description-Bioremediation is a process in which microorganisms degrade organic
contaminants found in soil and/or groundwater, converting them to less toxic or innocuous end
products. There are two general types of bioremediation: aerobic, which takes place in the
presence of oxygen, and anaerobic, which takes place in the absence of oxygen. Natural
bioremediation relies on indigenous microorganisms under existing site conditions, and is
likely to proceed under all alternatives, including the no action alternative. Enhanced
bioremediation is a process in which site conditions are modified to enhance the desired
microbial activity. Addition of nutrients (biostimulation), oxygen (bioventing), or other
amendments (lactic acid, edible oil substrates, oxygen releasing compounds, etc.) may be used
to enhance bioremediation. Acclimated microorganisms also can be added to the system
(bioaugmentation). Solutions such as surfactants may be utilized to enhance desorption of the
COCs and increase their bioavailability.
Effectiveness-While the low molecular weight organic COCs, in particular benzene, PCE, and
TCE, may be amenable to bioremediation, the PAHs, pesticides (DDD, DDT), and dioxin are
recalcitrant to biodegradation. In addition, those compounds that may be readily degraded
require different conditions for optimum degradation rates. For example, the highly
chlorinated benzenes may be reduced to less-chlorinated benzenes under anaerobic conditions,
but aerobic conditions are required for the degradation of chlorobenzene and benzene. In
addition, bioremediation would not address the metal COCs. While this technology can
U.S. EPA Region 3
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effectively treat some of the COCs, it cannot address the entire COC list. Bioremediation was
selected as the primary remedy for certain site soils and sediments in the 1995 ROD, but
treatability studies carried out by the PRP were not successful, and EPA elected to replace
bioremediation with the contingency remedy (ex situ LTTD).
Additionally, the increased chloride concentrations that would result from the dechlorination
process could have detrimental effects on both the soil bentonite containment barrier and GETS
components. Finally, the changes in contaminant composition would likely result in more
mobile intermediate species that could travel into the groundwater before complete
mineralization is achieved.
Implementability-Because of the need to distribute amendments throughout the treatment
zone, to maintain a minimum moisture content for microbial activity, and to ensure a specific
redox condition for the microbes, in situ bioremediation can be difficult to implement in soil.
Cost - Low to Moderate: Enhanced bioremediation is relatively inexpensive if carried out in
situ, ranging from $20 to $80 per cubic yard of soil (FRTR, 2002). It also does not require soil
excavation or expensive reagents. Enhanced bioremediation tends to be a long-term
technology, which may take years to complete cleanup.
Recommendation-Because of the lack of success in the treatability studies, in situ enhanced
bioremediation was eliminated from further consideration during the screening and evaluation
stage as a stand-alone treatment option.
3.3.4.9 Ex Situ Bioreactor/ In-Vessel Bioremediation
Description-In ex situ bioreactors, the excavated soils are mixed with water and other
additives in a vessel to create a slurry phase for biological treatment of excavated soils. The
slurry is mixed to keep solids suspended and microorganisms in contact with the soil
contaminants. Upon completion of the process, the slurry is dewatered, and the treated soil is
disposed or reused. Water resulting from dewatering soils also would need to be treated and
disposed.
Effectiveness-The ex situ bioreactor can be optimized to treat most organic contaminants.
This technology will not address the metal COCs.
Implementability-Slurry phase bioreactor vessels can be constructed at the site. Difficulties in
implementation of this TPO at the SCO site may result from the large quantities of soils that
would need to be excavated, processed, and dewatered for this site, the process time required
for treatment, the area that would be required for bioreactor construction, and the likely need
for sequential treatment stages to allow for aerobic and anaerobic reactions.
Cost -High: The estimated cost of bioreactors with off-gas treatment can range from $125 to
$160 per cubic yard of soil (FRTR, 2002).
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Recommendation-Because of uncertainties, relatively high costs and potential difficulties in
implementation, ex situ bioreactors were eliminated from further consideration during the
screening and evaluation stage.
3.3.4.10 Ex Situ Biopiles
Description-In this process, excavated soils are mixed with soil amendments and placed in
aboveground enclosures. The piles are aerated with blowers or vacuum pumps, and leachate is
collected. Moisture, heat, nutrients, oxygen, and pH can be controlled to enhance
biodegradation.
Effectiveness-This technology would require the design and construction of a pilot-scale
biopile system at the site to confirm its applicability. Biopiles can treat larger volumes and are
less costly than bioreactors. Biopile treatment is most applicable to treatment of
nonhalogenated VOCs and fuel hydrocarbons. Halogenated VOCs and SVOCs can be treated,
but the effectiveness of the process will vary, and inorganic contaminants will not be affected
(FRTR, 2002).
Implementability-As with other ex situ treatment technologies, soil stockpiling areas would
need to be properly lined to prevent spread of contamination. A leachate collection system
would also be required, potentially requiring treatment of the collected liquid. Any off-gas
from the soil would likely have to be treated to remove or destroy the VOCs. It is questionable
whether there would be enough area available to construct biopiles of sufficient size to treat all
of the excavated material resulting from the construction of a surface cap.
Cost - Moderate: Typical costs range from $30 to $60 per cubic yard of soil (FRTR, 2002).
Recommendation-While the technology will not treat all of the contaminants present on site, it
could be used to reduce the toxicity of excavated soil and make final disposal of the material
less costly. The technology was retained for possible use in the pretreatment of excavated
soils excavated during the construction of a surface cap.
3.3.5 Removal and Disposal TPOs
Removal cannot be considered a stand-alone option for the site but instead must be
incorporated into any technology that includes ex situ treatment or disposal of the contaminated
material.
Excavated soil can be disposed in an on-site or off-site landfill, either directly or after it has
undergone ex situ treatment. Excavated material, whether sent to a landfill off site or placed in
an on-site entombment, would likely be classified as hazardous waste under RCRA. This waste
classification could result in additional disposal restrictions. The presence of certain
compounds (such as dioxins and PCBs) at concentrations greater than land disposal restriction
limits might require that the soil be treated prior to disposal. Excavation of the entire
contaminated soil mass for disposal is not feasible. As a result, no disposal alternatives will be
U.S. EPA Region 3
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retained as stand-alone remedial option.
3.3.5.1 Excavation
Description - Removal of contaminated material would entail excavation of the soil where the
contamination is located.
Effectiveness - Excavation of contaminated soil would remove the on site risks from the
material, but the excavated materials would then have to be treated and disposed of off-site.
Implementability - While excavation of the entire volume of contaminated soil is not practical
because of the depth and volume of contamination, as well as the potential for damage to the
containment barrier and GETS, selected hot spots might be excavated for disposal or ex situ
treatment. Limited soil excavation would be needed for construction of the surface containment
barrier.
Cost - Low to High: Excavation costs and health risks associated with soil removal activities
must be considered as a part of any alternatives involving soil removal. These costs were
incorporated into the unit costs for cap installation.
Recommendation - Excavation was retained for further consideration in conjunction with
surface capping and ex-situ treatment technologies.
3.3.5.2 On Site Landfill
Description -A landfill will be constructed on site for disposal of excavated soil. Depending
on the volume of soil requiring disposal, there might be sufficient area available within the
groundwater containment barrier to accommodate construction of a landfill. Benefits,
constraints, and costs for the on-site landfill option would be similar to those described earlier
for the surface cap. Most likely, the on-site landfill would be constructed using the
Sedimentation Pond (see Figure 1.2). Because of the level of contamination and to minimize
the potential for the spread of soil contaminants, the landfill would be built to the RCRA
Subtitle C requirements.
Effectiveness-If properly constructed and maintained, an on site landfill could achieve
ecological and human health objectives at the SCD site by limiting contact with contaminated
soil and soil gas, reducing infiltration, and limiting contaminant mobility in the soil. By
limiting infiltration, a landfill would greatly reduce the potential for contaminants to spread via
the soil to groundwater pathway.
Implementability-Space limitations make this technology an impractical choice for disposal of
the entire contaminated soil volume, but an onsite landfill could be used to dispose of some
surface soils excavated as part of the construction of a surface cap at the site. On-site disposal
could easily be implemented using standard excavation and landfill construction technology.
Potential problems/issues associated with an on-site landfill include the need for perpetual
U.S. EPA Region 3
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Delaware
operation and management activities, the lack of waste treatment, and the potential for
contamination to migrate if the landfill fails.
Cost - Moderate: Measures to control water infiltration and waste leaching, including
construction of a bottom and side wall liner, increase costs relative to surface cap construction.
It is estimated that costs for landfill construction would be approximately 50% greater than
those for surface cap installation.
Recommendation-On-site landfilling of excavated soils was retained for consideration as an
option for surface soil disposal during surface cap construction.
3.3.5.3 Off Site Landfill
Description-Excavated soil from the source areas at the site are disposed in an off-site landfill
with or without treatment.
Effectiveness-Disposal of contaminated soil in an off-site landfill would be an effective option.
While disposal of contaminated soils at an existing off-site landfill may have the benefit
of not requiring construction of a new landfill, a nearby landfill designed to accept hazardous
wastes of the type present on site would have to be identified.
Implementability-A detailed contaminant analysis would be required before an off-site
treatment/disposal facility accepts materials. Because no landfills in Delaware would be able to
accept contaminated soils, the soils would have to be transported over longer distances. The
Model City landfill in New York is the closest permitted landfill that was identified as being
able to accept soils from the site, but there is no rail service to that landfill. Because of the
volume of contaminated soils requiring disposal and the capacity of commercial dump truck
trailers, use of this landfill would require hundreds of shipments traveling over 450 miles using
public roads. In addition to creating negative public perception and permitting issues, this
approach would increase the potential to spread contamination off site through spills or
accidents. Using railcars to transport the contaminated materials would reduce the number of
individual shipments, the potential for off site spread of contaminants, and the likelihood of
public perception problems. The closest acceptable landfill that can accept rail shipments is the
Wayne Disposal landfill in Belleville, Michigan. This landfill is over 580 miles from the SCO
Site. Additionally, the loading of railcars would require obtaining permission to use an area
located to the south of Governor Lea Road, constructing containment and loading features, and
transporting hundreds of waste loads across that road.
The presence of substantial quantities of cement and other debris on the ground surface at the
site means that it is likely that some off-site landfilling will be required. Because the
demolition debris consists largely of concrete, asphalt, steel reinforcing rods, and steel plate, it
is less likely, relative to the underlying and surrounding soil, that the debris would be
classified as hazardous waste. If this material can be classified as non-hazardous, it could be
disposed of in a landfill that is closer to the site (e.g., Tullytown in Pennsylvania).
Additionally, some of these materials could be recycled.
U.S. EPA Region 3
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Cost - High: Cost estimates for excavation and disposal of contaminated soils range from $210
- $350 per cubic yard of soil (FRTR, 2002). The costs for OU-3 are expected to be toward the
high end of these estimates because of the highly contaminated nature of the waste, increases in
fuel costs since the time the referenced estimates were developed, and the distance to an
appropriate landfill. Additional costs might be incurred if treatment is needed to meet land
disposal restriction requirements. Disposal of nonhazardous demolition debris would incur
lower costs because the debris could be disposed of in landfills located closer to the site.
Recommendation-Because of the potential for the spread of site contaminants, the likely
negative public perception issues, and the relatively high expected costs, transportation of
contaminated soils to an off-site landfill was eliminated from further consideration during the
screening and evaluation stage, but some demolition debris (reinforced concrete rubble and
asphalt) might need to be sent off-site for landfilling or recycling.
3.3.6 Monitoring of Site Conditions and Contaminant Levels
Description-By inspecting the site and collecting soil, soil gas, and groundwater samples for
analysis, progress of other remedial options can be tracked. For the first two years, air and
soil gas monitoring, including measurements of contaminants adsorbed to airborne particles,
would be conducted quarterly for all remedial alternatives to confirm that inhalation exposure
risks for onsite workers and others remain within the allowable human health criteria that are
expressed as PRGs. After the first two years sampling would be conducted on a semiannual
basis.
Effectiveness-While monitoring activities would not reduce the risks associated with the
contaminants, or the toxicity, mobility or volume of the contaminants at the site, these
activities are necessary for successful implementation of other remedial options. Surface soil
contamination could still be spread by stormwater runoff and wind-blown particulates.
Monitoring would be more effective in combination with other remedial options.
Implementability-Monitoring can be easily implemented.
Cost - The cost of monitoring site conditions and contaminants for the site would be very low
to low depending on analytical requirements and costs.
Recommendation-Monitoring of site conditions and site contaminants was retained for
further consideration in combination with other remedial options.
3.4 SUMMARY OF TREATMENT TECHNOLOGIES AND SELECTION OF
REPRESENTATIVE PROCESS OPTIONS
The process options that were retained for further consideration will be used as components of
the potential remedial alternatives in the subsequent sections of this Report. Results of the TPO
evaluation are summarized in Table 3.2.
U.S. EPA Region 3
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TABLES
-------
Table 3.1
Identification and Preliminary Screening of Soil and Soil Gas Technologies
For Standard Chlorine of Delaware Operable Unit 3
Page 1 of 3
General
No Action
Institutional
Controls
Containment
None
Institutional
Actions
Fencing
Surface Cap
Subsurface Cap
None
Zoning Ordinances
Restrictive covenants
Access Agreements
Security Fencing
Surface Cap -
Evapotranspiration (ET)
Surface Cap - Soil and Clay
Surface Cap - Chemical
Sealant
Surface Cap - Multilayer
Surface Cap - Asphalt or
Concrete
Subsurface Cap
Take no remedial action. Contaminated soil will be subject to natural
conditions and processes.
Restrict uses of the property and/or limit site access to minimize
exposure and protect site features
Require vapor intrusion control features for all new buildings
constructed on site; restrict groundwater use at the site
Provide access agreements to ensure access for monitoring of soil
gas and air contamination, groundwater sampling, and GETS(2)
operation
Surrounds site and restricts entry into contaminated areas but does
not mobilization/ transport of site contaminants.
Construct ET cap over contaminated areas to reduce infiltration of
precipitation into contaminated soils.
Construct single layer clay cap over contaminated areas
Construct chemical sealant cap using native soil mixed with a
binding agent to reduce the soil's permeability
Install impermeable multilayered surface cap (such as RCRA Subtitle
C cap) to encapsulate contaminated areas
Install low permeability asphalt or concrete cap to encapsulate
contaminated areas
Install a horizontal impermeable barrier within the subsurface at the
site;
Required for
consideration by
NCP
Potentially applicable
Potentially applicable
Potentially applicable
Potentially applicable
if used in conjunction
with other measures
Not effective for
controlling soil gas
contamination
Potentially applicable
Not applicable
because surface and
shallow native soils
are contaminated
Potentially applicable
Potentially applicable
Not applicable
because surface and
shallow native soils
are contaminated
-------
Table 3.1
Identification and Preliminary Screening of Soil and Soil Gas Technologies
For Standard Chlorine of Delaware Operable Unit 3
Page 2 of 3
Treatment
Treatment
(continued)
Removal
Chemical/Physical
Treatment
Thermal
Treatment
Biological
Treatment
Biological
Treatment
(continued)
Excavation
In Situ Chemical Oxidation
Ex Situ Chemical Oxidation
In Situ Soil- Vapor Extraction
(SVE)
In Situ Soil Flushing
Ex Situ Soil Washing
In Situ Thermal Desorption
Ex Situ Low Temperature
Thermal Desorption (LTTD)
Ex Situ Thermal Destruction
(Incineration)
In Situ Enhanced
Bioremediation
Ex Situ Bioreactor/ In- Vessel
Bioremediation
Ex Situ Biopiles
Excavation
Chemical oxidants are injected or mixed into the soil to convert
COCs to less toxic forms.
Chemical oxidants are applied ex situ to excavated soils
A vacuum is applied to the vadose zone aid in removal of VOCs and
SVOCs;
The off-gas is treated (e.g. by activated carbon adsorption)
Contaminants are extracted from the soil with an aqueous medium;
the injected fluid is recovered for treatment and discharge
Excavated soils are suspended in washing solution to concentrate and
extract contaminants
The soil is heated to low temperatures, air is then blown through the
soil as a carrier for desorbed organics; the off-gas is collected for
treatment and discharge.
Excavated soils are run through a thermal desorber for
removal/destruction of organic compounds.
Excavated soils are combusted at high temperatures in the presence
of oxygen to thermally destroy organic contaminants.
Environmental conditions are modified to improve biodegradation
A slurry phase bioreactor is constructed for in-vessel biological
treatment of excavated soils.
Analogous to the bioreactor but the vessel is replaced with above
ground enclosures; Have larger capacities than bioreactors;
Soils are excavated for further treatment or disposal or for
construction purposes
Potentially applicable
away from GETS
components
Potentially applicable
to excavated soils
Potentially applicable
Potentially applicable
Potentially applicable
Potentially applicable
Potentially applicable
to excavated soils
Potentially applicable
to excavated soils
Potentially applicable
Potentially applicable
Potentially applicable
Potentially applicable
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Table 3.1
Identification and Preliminary Screening of Soil and Soil Gas Technologies
For Standard Chlorine of Delaware Operable Unit 3
Page 3 of 3
General
Response
Action
Disposal
Monitoring
Technology
Type
Landfill
Site Monitoring
Technology Process Options
On-Site Landfill
Off-Site Landfill
Sampling and Site Inspection
Description of Process Option
An on-site landfill is constructed for disposal of excavated soils
Excavated soils are transported to an off-site landfill
Remedial measures are inspected to check for proper function and/or
damage. Samples are collected to check on and document site
remediation progress.
Pre-screening
Conclusion
Potentially applicable
Potentially applicable
Potentially applicable
in conjunction with
other measures
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Table 3.2
Evaluation and Screening of Technology Process Options (TPOs)
for Standard Chlorine of Delaware Operable Unit 3
Page 1 of 9
General
No Action
Institutional
Controls
None
Zoning
Ordinances
Restrictive
covenants
Access
Agreements
Public
Awareness
Programs
Take no remedial action.
Contaminated soil will be
subject to natural conditions
and processes.
Restrict uses of the property
and/or limit site access to
minimize exposure and protect
site features
Require vapor intrusion
control features for all new
buildings constructed on site;
restrict groundwater use at the
site
Provide access agreements to
ensure access for monitoring
of soil gas and air
contamination, groundwater
sampling, and GETS(2)
operation
Conduct Public Meeting and
issue fact sheets to educate
citizens about risks of site
contamination; Post warning
signs at site to alert people of
associated risks.
Rank = 5
Does not address risks from site
soils or soil gas.
Rank =4
Reduces but does not eliminate
human health risks from the site
and should be combined with
other technology options; Does
not address ecological risks.
Rank = 4
Reduces but does not eliminate
human health risks from the site
and should be combined with
other technology options; Does
not address ecological risks.
Rank = 4
Reduces but does not eliminate
human health risks from the site
and should be combined with
other technology options; Does
not address ecological risks.
Rank = 4
Reduces but does not eliminate
human health risks from the site
and should be combined with
other technology options; Does
not address ecological risks.
Rank = 1
Rank = 1
Can be easily
implemented
Rank = 1
Can be easily
implemented
Rank = 1
Can be easily
implemented
Rank = 1
Can be easily
implemented
No to Very Low
cost;
NoO&M
Very Low cost;
NoO&M
Very Low cost;
NoO&M
Very Low cost;
NoO&M
Very Low cost;
O&M Required
Retained as
baseline
comparison
Retained for
development
of remedial
alternatives in
combination
with other
TPOs.
Retained for
development
of remedial
alternatives in
combination
with other
TPOs.
Retained for
development
of remedial
alternatives in
combination
with other
TPOs.
Retained for
development
of remedial
alternatives in
combination
with other
TPOs.
-------
Table 3.2
Evaluation and Screening of Technology Process Options (TPOs)
for Standard Chlorine of Delaware Operable Unit 3
Page 2 of 9
General
Response
Action
Containment
Technology
Process
Options
Security
Fencing
Surface Cap -
Asphalt or
Concrete
Subsurface Cap
Description of Process
Option
Maintain and add to fencing
around the contaminated
portions of the site
Install low permeability
asphalt or concrete cap to
encapsulate contaminated areas
Install a horizontal
impermeable barrier within the
subsurface at the site;
Effectiveness*1'
Rank = 4
Reduces but does not eliminate
human health risks from the site
and should be combined with
other technology options; Does
not address ecological risks.
Rank = 2
As effective as multilayered cap
in controlling exposure and
spread of contamination;
Improved erosion control; Does
not allow for site revegetation;
Visually unappealing; Resealing
of cap relatively simple if
additional extraction or
monitoring wells needed.
Rank = 4
Does not address contaminated
surface soil (must be excavated
and treated separately); Limits
exposure and transport of
contaminants into groundwater;
Does not treat or remove
contamination; limits allowable
future uses.
Implementability(1)
Rank = 1
Can be easily
implemented
Rank = 2
Is easier to
construct than
multilayered cap;
Requires minimal
modification of GW
extraction system
and monitor wells;
Some soil
removal/treatment
needed; Requires
additional gas
collection system;
Perpetual
maintenance.
Rank = 3
Is relatively easy to
construct; Possibly
requires treatment
or disposal for
large volume of
excavated surface
soil; Requires
additional
stormwater and gas
collection systems;
Cost
Very Low cost;
O&M Required
Low to moderate
cost with lower
O&M than multi-
layer cap
Moderate to high
cost:
O&M required.
Screening
Conclusion
Retained for
development
of remedial
alternatives
Retained for
development
of remedial
alternatives
Eliminated
because
contaminated
surface soils
not addressed
and water
collection and
treatment
issues
-------
Table 3.2
Evaluation and Screening of Technology Process Options (TPOs)
for Standard Chlorine of Delaware Operable Unit 3
Page 3 of 9
General
Response
Action
Containment
Technology
Process
Options
Surface Cap —
Evapotranspirati
on (ET)
Surface Cap —
Single Layer
Surface Cap —
Chemical
Sealant
Description of Process
Option
Construct ET cap over
contaminated areas to reduce
infiltration of precipitation into
contaminated soils.
Construct single layer clay cap
over contaminated areas
Construct chemical sealant cap
using native soil mixed with a
binding agent to reduce the
soil's permeability
Effectiveness*1'
Rank = 4
ET cap will not address risks
from soil gas; Addresses soil
risks but contamination remains
in place; Reduces infiltration.
Rank =3
Addresses soil and soil gas risks,
but contamination remains in
place; Reduces infiltration.
Single layer cap has increased
potential of failure compared to
other surface caps;
Rank = 4
Soil (and likely soil gas) risks
remain if contaminated surface
soils used as part of cap;
Contamination still in place.
Implementability(1)
Rank = 2
Can be easily
constructed
compared to other
caps; Perpetual
maintenance.
Rank =2
Can be easily
constructed
compared to other
caps; Requires
additional gas
collection system;
Perpetual
maintenance.
Rank =4
Native surface soils
cannot be used in
cap construction
because of
contamination;
Perpetual
maintenance.
Cost
Low Cost;
Reduced O&M
requirements
Low cost
High O&M
Low cost
Low O&M
Screening
Conclusion
Eliminated
because
doesn't
address risks
from soil gas
Eliminated
because of
higher failure
potential
Eliminated
because
contaminated
native soils
can't be used
s
v 3-
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Table 3.2
Evaluation and Screening of Technology Process Options (TPOs)
for Standard Chlorine of Delaware Operable Unit 3
Page 4 of 9
General
Response
Action
Treatment
Technology
Process
Options
Surface Cap -
Multilayer
In Situ
Chemical
Oxidation
Description of Process
Option
Install impermeable
multilayered surface cap (such
as RCRA Subtitle C cap) to
encapsulate contaminated areas
Chemical oxidants are injected
or mixed into the soil to
convert COCs to less toxic
forms.
Effectiveness*1'
Rank = 2
Limits exposure and transport of
contaminants offsite;
Does not treat or remove
contamination; limits allowable
future uses; Reduces infiltration;
Limits reuse options for site.
Resealing of cap more difficult if
additional extraction or
monitoring wells needed.
Rank = 3
Potentially can treat most, if not
all, organic site contaminants to
eliminate site risks; Can
mobilize metals but will not treat
them.
Implementability(1)
Rank = 2
Some soil removal
and demolition or
modification of site
features
(particularly the
GW extraction
system and
monitoring wells
required; Requires
additional leachate
and gas collection
systems; Perpetual
maintenance.
Rank = 3
Cannot be applied
to entire site; Can
damage existing
groundwater barrier
wall; Multiple
injection points and
large amounts of
reagent may be
required.
Cost
Low to Moderate
Cost:
O&M required
Moderate cost to
high;
Pilot study
required
Screening
Conclusion
Retained for
development
of remedial
alternatives
Retained for
development
of remedial
alternatives in
combination
with other
TPOs.
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Table 3.2
Evaluation and Screening of Technology Process Options (TPOs)
for Standard Chlorine of Delaware Operable Unit 3
Page 5 of 9
General
Response
Action
Treatment
Technology
Process
Options
Ex Situ
Chemical
Oxidation
In Situ Soil-
Vapor
Extraction
(SVE)
In Situ Thermal
Desorption
Description of Process
Option
Chemical oxidants are applied
ex situ to excavated soils
A vacuum is applied to the
vadose zone aid in removal of
VOCs and SVOCs;
The off-gas is treated (e.g. by
activated carbon adsorption)
The soil is heated to achieve
boiling point or near boiling
point of contaminants, air is
then blown through the soil as
a carrier for desorbed
organics; the off-gas is
collected for treatment and
discharge.
Effectiveness*1'
Rank = 3
Could potentially treat all
organic contaminants in
excavated soils. Does not
address inorganic contamination.
Rank = 4
Effective for volatile
compounds, but not for SVOCs,
dioxins, PCBs or metals;
Effectiveness could be enhanced
by combining with thermal
desorption
Rank = 3
Is able to destroy or extract less
volatile compounds; works well
as an enhancement to SVE;
Could address SVOCs, PCBs,
and dioxins; Does not address
inorganic contamination.
Implementability(1)
Rank = 4
Excavation of
entire contaminated
soil volume not
feasible; Would
require construction
of an enclosed
system including
leachate collection
and treatment.
Rank = 2
Air permitting may
be required for
discharge of treated
off-gas; substantial
number of wells
required to treat
entire site.
Rank = 3
Air permitting may
be required for
discharge of treated
off-gas; Substantial
number of wells
required to treat
entire site; high
energy
requirements
Cost
Moderate to high
cost
O&M required
Low to high cost
Pilot study
required;
O&M required
Moderate to high
cost
Pilot study
required;
O&M required
Screening
Conclusion
Eliminated
because of
prohibitive
costs
compared to
other ex-situ
options and
incomplete
treatment.
Retained for
development
of remedial
alternatives in
combination
with other
TPOs.
Retained for
development
of remedial
alternatives in
combination
with other
TPOs.
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Table 3.2
Evaluation and Screening of Technology Process Options (TPOs)
for Standard Chlorine of Delaware Operable Unit 3
Page 6 of 9
General
Response
Action
Treatment
Technology
Process
Options
In Situ Soil
Flushing
Ex Situ Soil
Washing
Ex Situ Low
Temperature
Thermal
Desorption
(LTTD)
In Situ
Enhanced
Bioremediation
Description of Process
Option
Contaminants are extracted
from the soil with an aqueous
medium; the injected fluid is
recovered for treatment and
discharge
Excavated soils are suspended
in washing solution to
concentrate and extract
contaminants
Excavated soils are run
through a thermal desorber for
removal/ destruction of organic
compounds.
Environmental conditions are
modified to improve
biodegradation
Effectiveness*1'
Rank = 3
Complicated washing solution
regimen needed to treat all
contaminants; Would mobilize
contaminants and possibly
increase groundwater
contaminant levels.
Rank = 3
Complicated washing solution
regimen needed to treat all
contaminants.
Rank = 3
Excellent organic contaminant
removal; No inorganic
treatment; Higher temperatures
are required to destroy dioxins
and PCBs
Rank = 4
May not ensure the removal of
dioxins or highly chlorinated
compounds;
May take years to complete
cleanup; could result in more
mobile intermediate species that
could impact groundwater;
Previous studies unsuccessful.
Implementability(1)
Rank = 4
Injection of large
fluid volumes could
increase potential of
Potomac aquifer
contamination
Rank = 4
Excavation of
entire contaminated
soil volume not
feasible; Requires
expansion of GETS
or construction of
new treatment
system
Rank = 4
Excavation of
entire contaminated
soil volume not
feasible.
Rank = 3
Past studies by PRP
showed lack of
success
Cost
High cost
O&M required
High cost
Moderate to high
cost;
Pilot study
required
Low to moderate
cost;
Pilot study
required
Screening
Conclusion
Eliminated
because of
potential to
damage
Potomac
Retained for
possible use
with excavated
soils from
surface cap
construction
Retained for
possible use
with excavated
soils from
surface cap
construction
Eliminated
because of
unsuccessful
prior studies
and potential
harm to
barrier wall
and GETS
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Table 3.2
Evaluation and Screening of Technology Process Options (TPOs)
for Standard Chlorine of Delaware Operable Unit 3
Page 7 of 9
General
Response
Action
Technology
Process
Options
Ex Situ
Thermal
Destruction
(Incineration)
Ex Situ
Bioreactor/ In-
Vessel
Bioremediation
Description of Process
Option
Excavated soils are combusted
at high temperatures in the
presence of oxygen to
thermally destroy organic
contaminants.
A slurry phase bioreactor is
constructed for in-vessel
biological treatment of
excavated soils.
Effectiveness*1'
Rank = 1
Eliminates all exposure scenarios
if applied to full depth of
contamination onsite;
Incineration is very effective for
treating the organic contaminants
Rank =3
Conditions can be controlled to
promote desired processes;
Bioreactor might not treat all
contaminant classes
Implementability(1)
Rank = 4
Cannot be applied
to entire site;
Potential spread of
contamination
during transport;
Not practical to
excavate all
contaminated
materials;
Incinerators not
permitted in
Delaware Coastal
Zone.
Rank = 4
Difficult to
construct; Cannot
be applied to the
entire site;
Large quantities of
waste fluid are
generated and must
be treated
Cost
Very high cost
High cost
Screening
Conclusion
Retained for
possible off-
site use with
small
quantities of
soil
contaminated
with PCBs
and dioxins
Eliminated
because of
high cost and
uncertain
effectiveness
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Table 3.2
Evaluation and Screening of Technology Process Options (TPOs)
for Standard Chlorine of Delaware Operable Unit 3
Page 8 of 9
General
Response
Action
Treatment
Removal
Disposal
Technology
Process
Options
Ex Situ Biopiles
Excavation
On-Site Landfill
Description of Process
Option
Analogous to the bioreactor
but the vessel is replaced with
above ground enclosures;
Have larger capacities than
bioreactors;
Soils are excavated for further
treatment or disposal or for
construction purposes
An on-site landfill is
constructed for disposal of
excavated soils
Effectiveness*1'
Rank = 3
Extensive controls needed to
treat diverse contaminants;
May not treat all contaminant
classes;
Rank = 2
Could remove contamination if
all contaminated soil is removed
for treatment or off-site disposal
Rank = 2
A well designed landfill
eliminates the exposure scenarios
for contained soil;
Contamination is not treated
Implementability(1)
Rank = 3
Cannot be applied
to the entire site;
Easier to construct
than bioreactor;
Engineered
treatment area and
a leachate
collection and
treatment required
Rank = 4
Excavation of
entire contaminated
soil volume not
feasible; Part of
containment
construction and/or
ex-situ treatment
alternatives.
Rank = 3
Restriction on
landfilling exists for
some hazardous
wastes; Not
applicable for large
soil volumes;
Needs to be
maintained
indefinitely
Cost
Moderate to high
cost;
O&M may be
required
Low to high
cost;
No O&M
Moderate cost
Screening
Conclusion
Retained for
possible
limited
treatment of
soils excavated
during cap
construction
Retained for
development
of remedial
alternatives in
combination
with other
TPOs.
Retained for
possible
disposal of
soils excavated
during cap
construction
s
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Table 3.2
Evaluation and Screening of Technology Process Options (TPOs)
for Standard Chlorine of Delaware Operable Unit 3
Page 9 of 9
General
Response
Action
Monitoring
Technology
Process
Options
Off-Site
Landfill
Monitoring of
Site
Contaminants
Description of Process
Option
Excavated soils are transported
to an off-site landfill
Collect and analyze soil,
groundwater, and soil gas
samples to determine changes
in risks posed by untreated
contaminants
Effectiveness*1'
Rank = 2
Eliminates all exposure scenarios
if applied to full depth of
contamination onsite, but does
not eliminate contaminants.
Rank = 5
Does not address risks from site
soils or soil gas. Useful for
assessing progress of other
technologies.
Implementability(1)
Rank =3
No nearby landfills
accept hazardous
waste; Potential
spread of
contamination;
Potential regulatory
and public
perception issues
Rank = 1
Can be easily
implemented
Cost
Moderate to high
cost
Very Low to
Low Cost
Screening
Conclusion
Retained for
potential
disposal of
non-hazardous
demolition
debris only
Retained for
development
of remedial
alternatives in
combination
with other
TPOs.
(i) TPOs are ranked qualitatively for effectiveness and implementability, with 1 representing the most effective/easiest to implement and 5 representing the ineffective/impossible to implement
GETS - Groundwater Extraction and Treatment System
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4.0 DEFINITION AND SCREENING OF REMEDIAL ALTERNATIVES
The retained TPOs have been assembled into remedial alternatives that could potentially meet
the RAOs for the site. The remedial alternatives include a "no action" alternative as required
by the NCP, as well as combinations of various containment and treatment processes. ICs are
included as part of all alternatives, except for the "no action" option in part because the PRGs
developed in this FS Report are based on a restricted land use scenario. The proposed
alternatives are defined in Section 4.1 and summarized in Table 4.1. In Section 4.2, the
defined alternatives are evaluated qualitatively based on their effectiveness, implementability
and cost, and some of the alternatives are eliminated from consideration.
Most of the soil contamination at the site is confined to the area within the former facility
fence. As a former industrial site, the property has very little or no habitat value. The area is
partially paved over, with several containment and building pads remaining from previous
operations. As discussed earlier, this area is highly contaminated, with contamination spread
throughout most of the surface and subsurface.
Although only minimal evidence of contamination was found in the few samples collected from
the Northern Area during RD and RI sampling, drum remnants and solid chlorobenzenes were
discovered in this area during the construction of the Western Stormwater Basin.
Consequently this area has been combined with the On Facility area for the development, but
not the detailed costing of treatment alternatives. Additional sampling will be required to
delineate the extent of contamination in this area and determine to what extent remedial action
would be required in the Northern Area.
4.1 DEFINITION OF ALTERNATIVES
4.1.1 Alternative 1A: No Action
This alternative is required by the NCP and CERCLA. Alternative 1A requires no remedial
action to be taken at the site. The no action alternative serves as a basis against which the
effectiveness of all the other proposed alternatives can be compared. Under this alternative,
the site would remain in its present condition, and the soils would be subject to natural
processes only. No monitoring will take place to keep track of any changes. Five year reviews
of the site, required under CERCLA, would consist of at least a site visit and report
preparation.
4.1.2 Alternative IB: Limited Action
Alternative IB is a limited action alternative that would entail implementation of ICs and
revegetation of the site, without any treatment, containment or removal measures. Under this
alternative, all of the ICs introduced in Section 3.2.2 would be implemented. To limit the
human health risks from the site, zoning restrictions and restrictive covenants would be used to
prohibit almost all future uses of the land and most construction activities. ICs under this
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alternative would also include the requirement of vapor intrusion control/mitigation measures
for any future buildings on the site. This requirement could be implemented through the use of
a restrictive covenant. Additional covenants would be implemented to ensure that EPA and
DNREC would be able to access the site to monitor, operate, and maintain the components of
the existing remedial systems. Although PCBs were not found to be a soil risk driver based on
the available EPA Method 8081 data, it is somewhat likely, given the past site activities and
the detections of PCBs (using Method 1668a) in the underlying groundwater and adjacent
wetlands, that PCBs are present in some site soils. To comply with the PCB remediation waste
disposal requirements of TSCA, notifications would be included on the deeds of the affected
tax parcels to alert future owners of the presence of PCB contaminated soils along with
restrictive covenants to ensure that the parcels be maintained as "low occupancy" areas as
defined in 40 CFR 761.3. Alternative IB would also include some air monitoring to determine
to what extent contamination is being spread and to monitor site risks. Finally, security
fencing would be maintained and inspected to minimize unauthorized site entry. Similarly to
Alternative 1A, five year reviews of the site, required under CERCLA, would consist of at
least a site visit and report preparation.
The benefits of the Limited Action alternative include its low cost and relative ease of
implementation, accompanied by some decrease in the human health risks from the site through
limiting human exposure to the contaminated soil and soil gas. However, soil and soil gas
contamination would remain at the current levels, and would not be addressed by this
alternative. Ecological risks would remain unchanged as would the potential for the migration
of contamination via the soil to groundwater pathways. Contaminant migration via the soil to
sediment and soil to air pathways would be reduced somewhat as revegetation of the site would
reduce erosion from stormwater runoff and wind erosion. The current levels of soil and soil
vapor contamination exceed acceptable human health risks even for the limited land use
(industrial or commercial). Consequently, the land would need to remain undeveloped. It is
expected that this option would meet with considerable resistance from local citizens.
4.1.3 Alternatives 2A - 2D: Containment
The On Facility area is surrounded by the recently constructed soil bentonite groundwater
containment barrier. Depth to water within the containment barrier is approximately 40 ft bgs,
and is expected to drop to approximately 50 ft bgs as the pump-and-treat system continues to
operate. These features lend themselves to containment alternatives that utilize a horizontal
surface barrier. Contaminated surface soils that are excavated to construct a surface cap across
the On Facility portion of the site might require ex situ treatment and/or disposal if they cannot
be placed back in the area to be capped.
The surface barrier could be used alone (Alternative 2A) or in combination with some form of
treatment to address hot spots (Alternatives 2B-2D). In the cap plus treatment alternatives, the
surface cap would be constructed as described in Alternative 2A; however, some form of in
situ soil treatment would be used to address the most contaminated areas to improve the
potential long-term options for the site. Even though these treatment alternatives would remove
only a portion of the contamination, it is expected that they would decrease the potential for
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contaminant migration via the soil to groundwater pathway. Additionally, a reduction in soil
contaminant levels would reduce the operational costs of the surface cap gas recovery and
treatment system and could reduce the annual operating costs of the GETS. The treatment
options that are compatible with the surface cap installation are:
• 2B. In Situ SVE
• 2C. ISTD
• 2D. ISCO
In combination with each containment option, ICs would be used to restrict land use to
commercial, light industrial, naturalized open space, or parkland use and to require that any
construction activities minimize the impact on and repair any damage to the cap. Restrictive
covenants could be used to require incorporation of vapor intrusion control/mitigation
measures into any building constructed on the site, maintenance of the installed cap, and
provision of site access to EPA and DNREC to monitor, operate, and maintain all remedy
components. Although PCBs were not found to be a soil risk driver based on the available
EPA Method 8081 data, it is somewhat likely, given the past site activities and the detections
of PCBs (using Method 1668a) in the underlying groundwater and adjacent wetlands, that
PCBs are present in some site soils. To comply with the PCB remediation waste disposal
requirements of TSCA, notifications would be included on the deeds of the affected tax parcels
to alert future owners of the presence of PCB-contaminated soils along with restrictive
covenants to ensure that the parcels be maintained as "low occupancy" areas as defined in 40
CFR 761.3. All containment options would include some monitoring of site conditions and
possible collection of air and water (groundwater and surface water) samples to document the
effectiveness of the remedy and guarantee that cap integrity is maintained. Security fencing
would remain in place at least until cap construction is complete and the disturbed area is
stabilized. Maintaining the security fence beyond the completion of the cap construction and
site stabilization would reduce the possibility of damage to the cap because of vandalism, but
this would further limit the possible end uses of the site and incur extra expense.
Regardless of the containment approach used, demolition and removal of concrete slabs, tanks,
process columns, and other structures located on site will be required. Concrete resulting from
the demolition of building and tank farm foundations, secondary containment structures, storm
sewers, the former WWTP, and other structures would be crushed using a mobile concrete
crusher. The crushed material would be spread across the area to be capped. In the event that
crushing of the concrete or spreading of the crushed material proves to be unfeasible, the
concrete would be transported off-site to a landfill or recycling facility along with the
remaining demolition debris. Risks to construction workers from exposure to the COCs during
excavation and construction activities would also have to be monitored and mitigated.
4.1.3.1 Alternative 2A; Surface Cap Alone
The surface cap would be designed as described in subsection 3.3.3.1 of this FS Report.
Depending on the proposed use of the site, a concrete, asphalt, or multilayer cap would be
installed. While a multilayer cap using a clay and/or geosynthetic clay layer would allow
revegetation of the site and reduce surface water runoff to some extent, construction of an
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asphalt or concrete cap would require less modification of the GETS and associated monitoring
wells/piezometers. The asphalt and concrete cap options might also reduce the amount of
surface soil and demolition debris that would need to be treated and/or disposed of. The final
choice of material for a surface cap would be determined during the detailed alternative design
stage. Regardless of the type of cap emplaced, demolition and removal of concrete slabs,
tanks, process columns, and other structures located on site will be required. Demolition
debris could be crushed and incorporated into the soils under the cap or transported off-site to
a landfill or recycling facility.
A soil gas capture system would be included to minimize gas buildup beneath the cap and off-
gassing to the atmosphere. To improve capture, it would be beneficial to tie the cap into the
groundwater containment barrier on the south, west and east sides, even though this would
result in the capping of some less contaminated regions. Gas collection measures would be
placed along the proposed northern edge of the cap and at other areas around the cap.
The entire portion of the On Facility area that lies within the containment barrier (22.8 acres)
would be capped under this alternative as shown in Figure 4.1. This would effectively
eliminate the soil and soil gas exposure pathways in that area. To ensure that none of the
contamination in the rail siding area (a main pathway of the 1981 and 1986 spills) remains
exposed, the surface cap would be extended approximately ten foot beyond the containment
barrier in this area. Depending on subsequent sampling results from the Northern Area portion
of OU-3, some or all of that area might be incorporated under the cap. For purposes of cost
estimating, a worst case scenario in which the entire 60,000 square foot (approximately 1.4
acres) area would be capped was used for the Northern Area. Further delineation of the
contamination in this area must be conducted as part of the RD.
A surface cap would quickly and effectively achieve RAOs for the soil and soil gas by
preventing human and ecological contact with contaminated soils, and controlling the spread of
contamination from the capped area. Infiltration of water into the contaminated soils would be
minimized, addressing the soil to groundwater migration pathway and reducing the operational
costs of the GETS. Surface capping is an attractive alternative because it would isolate the
entire depth of contamination without excavation or treatment of the subsurface regions.
Construction of a surface cap would be considerably less expensive than other alternatives, and
installation of a surface cap can be completed in less than a year. Exclusive of the demolition
and disposal of the remaining surface and subsurface structures at the site, the cost for capping
the 22.8 acre area is estimated at between $7.0 million and $13.5 million. Adding the
Northern Area would increase this cost to between $7.4 million and $14.3 million. Demolition
of the remaining site structures (i.e., warehouse, tank farm foundations and containment
structures, abandoned storm drains and utilities, roads), crushing and spreading of the
concrete, and off-site disposal of the remaining debris would add approximately $4.1 million to
the total costs. Project support activities (e.g., design, construction management, project
management, waste management, etc.) would add another $4.3 to $4.4 million to the project
total. If site soils excavated to complete construction of the cap cannot be placed back in an
area that will be covered by the cap, costs for treatment and/or disposal of the excavated
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material must be added to the above price range. Technologies for addressing the excavated
materials are discussed following the presentation of Alternative 2D.
The primary deficiencies of this alternative are that, without additional treatment measures, the
COCs would not be removed or destroyed in a reasonable time frame. However, the capping
of the area would eliminate the human and ecological exposure pathways related to soil,
sediment, and soil gas. Additionally, a properly constructed and maintained cap would greatly
reduce the potential for precipitation to infiltrate through the contaminated OU-3 soil and
would thus reduce the potential transportation of additional contamination into the
groundwater. The cap would likely have to be maintained into perpetuity, resulting in
continuing inspection, maintenance, and repair expenses. Simple containment of the
contaminants might also meet with some resistance from nearby residents, and future
construction and site use alternatives would be limited.
4.1.3.2 Alternative 2B; Surface Cap with In Situ SVE
Alternative 2B incorporates all of the features of Alternative 2A but adds an SVE system to
address "hot spot" contamination. By equipping the surface cap with an SVE system,
contaminant toxicity and volume would be reduced, and migration of contaminants into the
groundwater could be further reduced. In addition to the gas recovery system that would be
installed with the cap, multiple SVE wells would be placed in some or all of the hot spots
identified in Section 1.5.1 and shown on Figure 4.1. The total number of SVE wells needed
would be determined based on the areas of influence observed during pilot studies that would
be conducted at the site as part of the design process. The sandy soils that underlie the site and
the relatively deep water table (over 40 ft bgs) indicate that larger radii of influence (15 to 25 ft
per well) can be expected. Pilot studies would also be used to quantify the potential
contaminant reductions that could be achieved by SVE at the site. Captured vapor would be
treated (along with the gases from the cap gas recovery system) with activated carbon or a
condensing system before being released into the atmosphere. Thermal and catalytic oxidizers
have been eliminated as potential off-gas treatment options because the chlorinated site
contaminants would be corrosive and require the additional use of a scrubber system.
Although SVE would not effectively treat metals, PCBs, dioxins, or most of the SVOCs, it
would help reduce the soil gas concentrations and would likely remove substantial contaminant
mass. Additionally, SVE could be used in fairly close proximity to the soil bentonite
containment barrier without significant risk of damage. Because of the large volume of soils
(approximately 610,000 cubic yards) that would be treated in this approach, an SVE system of
the type envisioned here would likely add between $3.1 million and $9.2 million to the cost of
the cap alternative. These estimates assume unit treatment costs between $5 and $15 per cubic
yard. If site soils excavated to complete construction of the cap cannot be placed in an area that
will be covered by the cap, the costs for treatment and/or disposal of the excavated material
would need to be added to the total cost range stated above.
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4.1.3.3 Alternative 2C; Surface Cap with In Situ Thermal Desorption
In this alternative, the SVE system in 2B would be supplemented with heat to enhance removal
of organic contaminants including SVOCs, dioxins, pesticides, and PCBs. As mentioned
previously, ISTD could be achieved by steam injection, hot air injection, ER heating, or
thermal conductance heating. Because of the temperatures necessary for volatilization of the
chlorobenzene compounds, it is likely that neither steam injection nor air injection would be
effective. Pilot studies would be required to determine appropriate temperatures, identify well
placements for effective treatment, and quantify the potential reduction that could be achieved
by ISTD. Because of the potential for the heating to dry out the clay that would be used in the
barrier layer of a multilayer cap, ISTD might be applied to the aforementioned hot spots before
construction of that type of cap. Alternatively, the zones nearest to the cap could be left
unheated. Because some of the worst contamination lies in the subsurface soils close to the
western leg of the soil bentonite containment barrier, ISTD would likely be augmented with
some regular SVE wells to avoid damage to the barrier but achieve at least partial treatment in
this area.
It is estimated that using ISTD to treat the 610,000 cubic yards of soil that compose the "hot
spot" areas prior to installing a surface cap would increase the On Facility remedy costs by
approximately $76.2 million to $122.0 million. If site soils excavated to complete construction
of the cap cannot be placed in an area that will be covered by the cap, costs for treatment
and/or disposal of the excavated material would need to be added to the previously stated price
range.
4.1.3.4 Alternative 2D; Surface Cap with ISCO
This alternative includes all of the features from Alternative 2A, but oxidants would be either
injected or mixed into the soils of the "hot spot" areas. As opposed to the other alternatives in
which treatment could continue during and following the cap construction, ISCO would be
performed to reduce contaminant concentrations before the construction of a surface cap. This
sequential effort would be utilized to ensure that the cap integrity would not be impacted by the
oxidants or disrupted by soil mixing activities. Additionally, because of concerns regarding
possible chemical attack, ISCO would not be used near the containment barrier. Increased
chloride concentrations that would result from the oxidation of site contaminants could also be
detrimental to the long term effectiveness of the soil bentonite containment barrier and GETS.
Further compatibility testing would be required to determine whether this technology could be
used without damaging these two features. It is estimated that adding ISCO treatment of the
"hot spot" areas to the surface capping approach would increase the facility remedy costs by
approximately $18.3 million to $61.1 million.
4.1.4 Options for Excavated Soil from Surface Cap Construction
Removal of from one to four feet of surface soil might be required during surface cap
construction. Given that the total proposed area to be capped is ranges from 22.8 to 24.2 acres,
the total excavated volume would be in the range of 37,000 to 156,000 cubic yards.
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Because large areas of surface soil at the facility are contaminated, excavated soil would need
to be treated or properly disposed of if it cannot be reintegrated into the area being covered by
the cap. This soil can either be landfilled on site as hazardous waste or treated ex situ before
on site disposal or utilization. Options 1 through 4 for dealing with the excavated surface soil
are detailed below. While these approaches could effectively deal with some or all of the
contaminants in the excavated soil, the most cost-effective method of dealing with these
materials would be to integrate them back into the soils that would be covered by the surface
cap. Consequently, no detailed analysis of these contingency measures will be provided
beyond the screening level examination presented in this section.
4.1.4.1 Excavated Soil Option I; On-Site Landfilling
Under this option, an on-site landfill would have to be designed and constructed for the
disposal of excavated surface soils that are above PRGs. A landfill can be constructed in the
northern portion of the site, most likely in place of the Sedimentation Pond (see Figure 1.2).
The Sedimentation Pond now contains highly contaminated sediment covered with water. The
liner in the basin has deteriorated and the contaminants are leaking into the soil below. Site
preparation for construction of a new landfill at the basin location would involve removing and
dewatering the sediments and a portion of the underlying contaminated soils. The removed
water would be treated in the existing groundwater treatment system. The remaining
sediments and soils would be placed into the newly constructed landfill.
The TSSA was constructed to contain approximately 20,000 cubic yards of material. The
TSSA crowns at approximately 9 ft above ground surface, and covers 1.5 acres. If an on-site
landfill were constructed to a height approximately three times that of the TSSA, it is estimated
that an area of approximately one to three acres would be required to contain the excavated
soil. Assuming that the unit costs for constructing an on-site landfill would be approximately
50% greater than the capping costs described above, it is expected that the additional cost of
the landfill would be between $340,000 and $2.25 million.
This option does not provide treatment or eliminate the COCs from the excavated soils. As in
the case of the surface cap, the on-site landfill would need to be maintained into perpetuity.
4.1.4.2 Excavated Soil Option II; Ex Situ LTTD / Incineration
Under this option, excavated surface soils would be treated ex situ, using a mobile LTTD unit
equipped with an off-gas collection and treatment system. Although LTTD could substantially
reduce organic contaminant levels, it would not address inorganic contamination. Treated soils
determined to have metals concentrations in excess of the PRGs would have to be landfilled on
site or shipped to an off-site industrial landfill.
Treated soils and untreated soils that do not exceed PRGs could be reused in the construction
of a multilayer cap or disposed of on site. The reuse of these soils would require that certain
logistical issues be addressed. Primary among these are achieving sufficient treatment
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throughput to keep up with surface cap construction rates and ensuring sufficient soil storage
area is available.
In LTTD, temperatures are usually raised to approximately 200 °F to 800 °F. A pilot test or
test-burn would need to be conducted to determine whether the LTTD unit is capable of
removing/destroying the dioxins, PCBs, and other COCs present in the soils. If it is
determined that the technology cannot sufficiently treat PCBs and dioxins, the affected soils
would probably need to be shipped off-site for incineration and/or disposal. Additionally,
LTTD would not address inorganic contamination that has been found throughout the site.
Although a certain amount of wastewater would be generated from on-site LTTD treatment,
the water could be treated in the GETS. Assuming that 30 percent of the excavated material
would need to be incinerated and average unit costs of $150/cubic yard for LTTD and
$900/cubic yard for incineration, the expected added costs related to this treatment option
would be approximately $13.9 million to $58.5 million.
4.1.4.3 Excavated Soil Option III; Ex Situ Biopile Treatment
This option would require the design and construction of a biopile system at the site. The
excavated soil would be mixed with soil amendments and placed in enclosed aboveground
aerated piles, equipped with aeration and leachate collection systems. Moisture, heat, nutrients,
oxygen, and pH can be controlled to enhance biodegradation. Collected liquid waste would be
treated in the existing groundwater treatment system, potentially requiring an update to the
current NPDES permit. The air leaving the soil also would have to be treated to remove or
destroy the VOCs. As with LTTD, organic contamination would be reduced, but it is unlikely
that inorganic contamination would be reduced. Treated soils determined to have metals
concentrations in excess of the PRGs would likely have to be landfilled on site.
Halogenated benzenes are the primary COCs in the surface soils. Highly halogenated
compounds are not readily biodegraded under aerobic conditions, but benzene and
chlorobenzene (potential daughter products of the reductive dechlorination of chlorobenzenes)
typically degrade more readily in aerobic environment. Potentially, an anaerobic stage could be
used to dehalogenate chlorinated compounds and make them more amenable to biodegradation,
followed by aerobic degradation. Pilot studies would be required to determine the specific
requirements for implementing this option.
Assuming the same logistical issues that are listed in Excavated Soil Option II can be
overcome, this option would likely add between $1.7 million and $7.0 million to the cap
construction costs. This range assumes an average unit cost of $45 per cubic yard of soil
treated.
4.1.4.4 Excavated Soil Option IV; Ex Situ Soil Washing
The principles of operation for the soil washing system were described in the TPO section.
Assuming that most of the soil contaminants are adsorbed to fine particles, the amount of
contaminated soil that needs to be landfilled could be significantly lowered by separating fine
U.S. EPA Region 3
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Delaware
soil particles from bulk soil using ex situ soil washing.
The washing solution can be augmented with a leaching agent, surfactant, or pH adjustment to
help remove the contaminants. The system should also include an air treatment unit (e.g.
carbon adsorption) to remove VOCs. Pilot studies would be needed to determine the specific
requirements for implementing this technology and to formulate the washing solutions. The
groundwater treatment system should be capable of treating the resulting liquid wastes,
although some modification might be required.
The same logistical issues that are listed in Excavated Soil Option II would need to be
overcome for this option to be considered. Assuming an average unit treatment cost of
$150/cubic yard, this option would likely add between $5.6 million and $23.4 million to the
cap construction costs.
4.1.5 Alternatives 3A - 3D: In Situ Treatment
The entire contaminated area could possibly be treated in situ without construction of a cap.
This approach, if successful, would ultimately eliminate the risks associated with soil and that
portion of the soil gas risk that is the result of soil contamination. Soil gas risks related to the
presence of groundwater contamination and non-aqueous phase liquid (NAPL) will continue
until these contaminants are cleaned up. Groundwater and NAPL contamination are being
addressed as part of OU-1.
If controlled properly, ISTD (Alternative 3A) could remove all COCs, including SVOCs,
PCBs, and possibly, to a lesser extent, dioxins from the site soils. Additional controls and
higher temperatures necessary to achieve dioxin removal with SVE could be avoided by adding
ISCO to treat regions contaminated with certain recalcitrant COCs, provided these regions are
not located close to the containment wall (Alternative 3B). Alternatively, soils from areas with
high concentrations of dioxin and other recalcitrant COCs could be excavated and shipped off-
site for incineration (Alternative 3C). Instead of using ISTD, most of the contaminated soils
could be treated using ISCO, with SVE utilized only in the regions close to the wall
(Alternative 3D). In any treatment alternative, pilot studies would be required to determine
treatability of the site contaminants and optimize the treatment application. Because the PRGs
reflect the assumption that ICs will be utilized as part of any remedy for the site, ICs would be
used to restrict land use to commercial, light industrial, naturalized open space, or parkland
use regardless of the remedial alternative that is selected.
Although PCBs were not found to be a soil risk driver based on the available EPA Method
8081 data, it is somewhat likely, given the past site activities and the detections of PCBs (using
Method 1668a) in the underlying groundwater and adjacent wetlands, that PCBs are present in
some site soils. Therefore, depending on the clean up levels achieved, notifications might be
required on the deeds of the affected tax parcels to alert future owners of the presence of PCB
contaminated soils and restrictive covenants might be employed to ensure that the parcels are
maintained as "low occupancy" areas as defined in 40 CFR 761.3. Finally, security fencing
would remain in place at least until clean up goals have been achieved and any disturbed area
U.S. EPA Region 3
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County,
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is stabilized. These alternatives would include at least some monitoring to determine whether
any contaminant rebound occurs.
Regardless of the type of treatment used, demolition and removal of concrete slabs, tank farm
foundations and containment structures, process columns, the warehouse, and other structures
located on site will be required. Demolition debris would be transported off-site to a landfill
or recycling facility.
4.1.5.1 Alternative 3A; ISTD/SVE for Entire On Facility Area
Under this alternative, a vacuum would be applied at several extraction wells throughout the
On Facility area to extract volatilized contaminants. Because SVOCs, PCBs, and dioxins are
present, SVE would be thermally enhanced using one of the available techniques, such as
thermal conduction or ER heating. The installed heating and extraction wells must be thermally
resistant to withstand the high temperatures. ISTD heating wells are typically constructed of
carbon steel casings with combination heating/extraction wells constructed of a carbon steel
outer casing with a stainless inner casing. Because of the acidic nature of the groundwater at
the site, it is possible that wells will need to be constructed of stainless steel. Some form of
surface cap or liner would be utilized to minimize fugitive emissions and the potential for
short-circuiting. The collected vapor would be treated in an activated carbon system and
discharged. Compliance with the substantive provisions of air discharge permit requirements
would likely be required. The duration of operation and maintenance for an ISTD system is
typically in the range of several months to a few years.
Pilot treatability studies and additional sampling are recommended before ISTD is implemented
so that well placement and operating parameters (such as temperature and required vacuum)
can be optimized. Based on the estimated soil volumes requiring treatment (presented in
Tables 2.4 and 2.5) and the aforementioned unit costs for this technology, it is expected that an
ISTD remedy would cost between $124.2 million and $162.2 million to complete.
4.1.5.2 Alternative 3B; ISTD Combined with ISCO for Select Locations
This alternative is similar to Alternative 3A, except that some of the soils containing certain
recalcitrant COCs would be treated with ISCO. Treatability studies would be required to
ensure that ISCO would be capable of destroying these COCs. Additional sampling would be
needed to confirm which areas would be treated with ISCO. Of the identified areas of
contamination at the site, ISCO would likely be used to address the off-product/PCB
concentration area and portions of the former process area. If shown to be effective in pilot
tests, the use of ISCO to address areas could possibly allow the use of lower temperatures for
the ISTD and decrease overall remedial costs. Using the estimated soil volumes requiring
treatment presented in Tables 2.4 and the aforementioned unit costs for ISTD and ISCO, and
assuming that 10% of the contaminated soils would be addressed with ISCO, the total costs of
this combined treatment approach would likely fall in the range of $104.6 million to $151.8
million.
U.S. EPA Region 3
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4.1.5.3 Alternative 3C; ISTD with Excavation and Off-Site Incineration of Dioxin
Contaminated Soils
This alternative is similar to Alternative 3B, except that some of the soils containing dioxin and
other recalcitrant COCs would be shipped off site to be incinerated and disposed of. To
develop costs for this alternative, the estimated soil volumes requiring treatment presented in
Tables 2.4 and 2.5, the aforementioned unit costs for ISTD, and an average incineration cost
of $900/cubic yard were assumed. If the total volume of dioxin contaminated soils is sent off
site for incineration, it is estimated that the cost of this alternative would range between $226.9
million and $264.9 million.
4.1.5.4 Alternative 3D; ISCO with SVE near the Wall
Under Alternative 3D, Fenton's Reagent would be applied, either through subsurface injections
or soil mixing, to achieve ISCO throughout almost the entire contaminated soil volume in the
former facility area. Because of concerns about the possible impacts of the oxidation process
(or the resulting increase in chloride levels) on the containment barrier, the use of ISCO would
be restricted to areas more than 25 ft from the barrier. If soil mixing were selected as the
application method, this zone of prohibition would likely be increased to address structural
stability concerns. Within those portions of the site where ISCO is prohibited, SVE wells
would be installed to provide treatment of VOC contamination.
Although earlier bench scale testing did show effective treatment of multiple chlorobenzenes,
PRGs were not available at the time, and not all species that pose ecological and/or human
health risks were monitored. Consequently, additional testing would be necessary to ensure
that those species that drive these risks would be sufficiently treated and to optimize the
required dosing schemes. Because soil concentrations have been shown to vary substantially
across the former facility area, additional characterization of the site would be required to
identify dosing/application requirements. Pilot scale testing for the SVE component would be
needed to determine an accurate radius of influence so that the spacing of injection wells, if
utilized, could be optimized.
Because the added volume of liquid oxidants required to achieve contaminant treatment could
increase the hydraulic head in the Columbia Aquifer, additional groundwater extraction wells
and modifications to the treatment system might be required. A modification to the NPDES
permit equivalence for the GETS also might be required to account for any additional volume
of treated effluent.
The costs for this alternative were developed using the estimated soil volumes presented in
Table 2.4, the aforementioned unit costs for ISCO, and an average SVE cost of $15 per cubic
yard. Assuming that 10% of the contaminated soils would be addressed with SVE, the total
costs of this combined treatment approach would likely fall in the range of $25.8 million to
$82.9 million.
U.S. EPA Region 3
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County,
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4.2 SCREENING OF REMEDIAL ALTERNATIVES
The assembled alternatives defined above were screened based on their effectiveness,
implementability, and cost. The purpose of this evaluation is to reduce the number of
alternatives that will undergo a more thorough and extensive analysis as the FS progresses. In
terms of effectiveness, each alternative was ranked on a scale of 1 (complete destruction or
removal of all site contaminants) to 5 (no or minimal destruction of removal of site
contaminants). With regard to implementability, the alternatives were ranked on a scale of 1
(no construction or O&M required) to 5 (not feasible to implement). Alternative costs were
rated on a scale of very low to very high using the following ranking brackets:
• Very Low: $0 to $4.99 million
• Low: $5 million to $14.99 million
• Medium: $15 million to $24.99 million
• High: $25 million to $49.99 million
• Very High: > $50 million.
The results of the screening are summarized in Table 4.2. Based on the results of the
screening process the following alternatives will be carried forward for more detailed analysis:
• Alternative 1: No Action (required)
• Alternative 2A: Surface Cap
• Alternative 2B: Surface Cap with SVE
• Alternative 2C. Surface Cap with ISTD enhanced SVE
If possible, soil excavated during the cap construction process should be placed back into the
area that will be capped. In case it is not possible to reintegrate the excavated soil, the
following options for dealing with this material should be considered as contingency measures:
• Option I: On Site Landfilling
• Option II: Ex Situ LTTD/Landfilling
• Option IV: Ex Situ Soil Washing
U.S. EPA Region 3
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TABLES
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County, Delaware
Table 4.1
Summary of Remedial Alternatives
for Standard Chlorine of Delaware Operable Unit 3
Page 1 of 2
No Action
Institutional
Controls
Containment
Removal
In Situ
Treatment
Ex Situ
Treatment
Disposal/
Discharge
Monitoring
None
Zone Ordinances;
Restrictive
covenants; Access
Agreements
Security Fencing
Horizontal Surface
Cap
Excavation
In Situ Chemical
Oxidation
In Situ Soil-Vapor
Extraction (SVE)
In Situ Thermal
Desorption (ISTD)
Ex Situ Biopiles
Ex Situ Thermal
Destruction
(Incineration)
Ex Situ Low-
Temperature
Thermal Desorption
(LTTD)
Ex Situ Soil
Washing
On-Site Landfill
Off-Site Landfill
Additional Discharge
to Surface Water
Site Inspections and
Media Samnline
No Action
•
•
•
•
•
.(i)
•
•
•
•
•
•
.(i)
•
•
•
•
•
•
•
.(i)
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Standard Chlorine of Delaware Site Feasibility Study Report
U.S. EPA Region 3
HydroGeoLogic, Inc. July 2009
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County, Delaware
Table 4.1
Summary of Remedial Alternatives
for Standard Chlorine of Delaware Operable Unit 3
Page 2 of 2
General
Response
Action
Studies
Technology Process
Options
Additional
Characterization
Sampling
Pilot/Treatabilitiy
Studies
No Action
Alternative
Alternative
1A:
No Action
: : : Limited : : : :
: : : : ACtMW : : : : :
^Alternative::
: : Alternate : :
:::::: IB?: ::::::
• - - - i ^liyfl \i£ jj- ' ' ' '
Containment Alternatives (Surface Cap)
Alternative
2A:
Surface Cap
•
Alternative
2B:
Surface
Cap with
In Situ
SVE
•
.
Alternative
2C:
Surface Cap
with
Thermally
Enhanced In
Situ SVE
•
.
; ; AllCrHatWe; ; ;
: : Surface: Cap : :
::Wltt:In:Sltti:::
::::::::»:::::::::
Treatment Alternatives
: : : : :t .-. :sHt,, : : : : :
: : : : Ui:M.tli: : : : :
: : : Thermal: : : :
::::::::#::::::::
' ' l^fllJLJ' with ' ' '
:::::::«::::::::
w *
; ; ; IKTI&wiflih ! !
' 'RfeJti0i^^ii ftitu '
> > >• >*riri?*T' > >>>>>>">
' '1» ' ' ' tvvt' ''*''*'
;;;;;; -SOilS !!!!!!
::::::::«.::::::::
; AltftrnapYP: :
: JSC0:wlth : :
::ȴE:Near:::
:th«:BSjWte*::
:::::::»::::::::
Excavated Soil Options (Surface Cap)<3)
Excavated
Soil Option
I: Onsite
Landfilling
Excavated
Soil Option
II: Ex Situ
LTTD/
Incineration
.
: : IxeHv&tfed : :
' 'kMMl C/lMlCill '
:iH;:Ex:SitB::
;;;;BftJ|»lle::::
: : freatwaat : :
Excavated
Soil Option
IV: Ex Situ
Soil
Washing
.
Note - Shaded alternatives have been eliminated from further consideration
(1) - Off site landfilling would only be used for disposal of demolition debris.
Standard Chlorine of Delaware Site Feasibility Study Report
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HydroGeoLogic, Inc. July 2009
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County, Delaware
Table 4.2
Summary of Remedial Alternatives
for Standard Chlorine of Delaware Operable Unit 3
Page 1 of 4
General
No Action
Alternative 1:
No Action
Take no remedial action. Contaminated soil
will be subject to natural conditions and
processes;
Five year reviews will be conducted.
Rank = 5
Does not eliminate human health or
ecological risks;
Fails to meet identified ARARs.
Rank = 1
No construction or operation and maintenance (O&M)
required.
Very Low
Retained as a baseline for other
alternatives
Institutional
Controls
Monitoring, and
Containment
(Security Fencing
Only)
Alternative IB:
Limited Action
Take no remedial action. Contaminated soil
will be subject to natural conditions and
processes;
Zoning ordinances, restrictive covenants
used to restrict future site uses;
Public awareness programs used to alert
community of hazards related to site.
Fencing and warning signs used to limit
unauthorized access;
Revegetation of site to provide some
stabilization of surface soils;
Periodic monitoring of site conditions and
sampling of air;
Five year reviews will be conducted.
Rank = 4
Reduces human health risks but does not
eliminate or reduce ecological risks;
Does not address soil to groundwater
pathways.
Future site use severely limited.
Fails to meet identified ARARs.
Rank = 1
Minimal regrading and planting of site required. No O&M
required.
Very Low
Not retained because of failure
to be protective of the
environment and to meet
ARARs
Containment
Alternative
2A: Surface
Cap
ICs(2);
Horizontal surface barrier(3);
Treatment and disposal of excavated soil
that can not be reintegrated into area under
cap(4);
Off-site disposal of demolition debris.
Gas capture system under cap with
activated carbon off-gas treatment;
Security fencing to remain in place at least
until cap is completed;
Periodic monitoring of site conditions and
sampling of media;
Five year reviews will be conducted.
Rank = 2
Prevents human and wildlife contact with
contaminated soils;
Controls spread of contamination
addressing all contaminant migration and
exposure pathways;
Does not permanently remove or treat
contamination;
Limits the allowable future uses and
construction alternatives;
Allows compliance with most identified
ARARs.
Rank = 2
Relatively easy to construct;
Compatible with IGR but some modifications necessary to
protect piezometers, extraction wells, and monitor wells;
Might require treatment and disposal of 1 to 4 ft of soil from
cap area;
Monitoring and O&M required indefinitely.
Low to Medium
(Approx. $13.3 - $22.9 million)
Retained for detailed analysis
Containment
Treatment
and
Alternative 2B:
Surface Cap
with In-Situ
SVE
ICs(2);
Horizontal surface barrier®;
Treatment and disposal of excavated soil
that can not be reintegrated into area under
cap(4);
SVE recovery wells in identified hot spots
and gas capture system under cap;
Activated carbon treatment system for
captured gas;
Security fencing to remain in place at least
until cap is completed;
Periodic monitoring of site conditions and
sampling of media;
Five year reviews will be conducted.
Rank = 2
Same as Alternative 2A, with additional
long-term benefits from removal of VOCs;
SVOCs, dioxins, and PCBs will not be
removed;
Allows compliance with most identified
ARARs.
Rank =3
Compatible with IGR but some modifications necessary to
protect piezometers, extraction wells, and monitor wells;
Might require treatment and disposal of 1 to 4 ft of soil from
cap area;
Requires pilot studies, construction, O&M of SVE system;
Monitoring and O&M of cap required indefinitely;
Medium to High
(Approx. $16.4 - $32.1 million)
Retained for detailed analysis
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County, Delaware
Table 4.2
Summary of Remedial Alternatives
for Standard Chlorine of Delaware Operable Unit 3
Page 2 of 4
General
Response Action
Alternative
Summary of Alternative
Effectiveness'1
Implementability0
Cost
Screening Conclusion
Containment
Treatment
and
Alternative
2C: Surface
Cap with ISTD
Enhanced SVE
ICs(2);
Horizontal surface barrier®;
Treatment and disposal of excavated soil
that cannot be reintegrated into area under
cap(4);
SVE recovery wells in identified hot spots
and gas capture system under cap;
Soil is heated using radio frequency
heating, electrical resistance, thermal
conductance, hot air injection, or steam
injection;
Activated carbon treatment system to treat
captured organics not destroyed by heating;
Security fencing to remain in place at least
until cap is completed;
Periodic monitoring of site conditions and
sampling of media;
Five year reviews will be conducted.
Rank = 1
Same as Alternative 2A, with additional
long-term benefits from removal of COCs
in hot spots;
Potentially capable of destroying/removing
most SVOCs, VOCs, PCBs and dioxins;
Non-VOC contamination will remain in
areas adjacent to bentonite containment
barrier;
Allows compliance with most identified
ARARs.
Rank = 3
Same as Alternative 2C with additional effort for ISTD
construction, higher electrical costs, and shorter O&M
period for SVE;
Only unheated wells can be used within 10 ft of containment
barrier;
Might require treatment and disposal of 1 to 4 ft of soil from
cap area;
Reduces long term carbon usage and SVE O&M as
compared to Alternative 2B, but requires higher short term
energy usage;
Monitoring and O&M of cap required indefinitely.
Very High
($89.5 - $144.9 million)
Retained for detailed analysis
Containment and
Treatment
Alternative
2D: Surface
Cap with ISCO
ICs(2);
Horizontal surface barrier(3);
Treatment and disposal of excavated soil
that cannot be reintegrated into area under
cap(4);
Use of Fenton's Reagent or persulfate
compound to oxidize organic contaminants;
ISCO prior to cap construction
Security fencing to remain in place at least
until cap is completed;
Periodic monitoring of site conditions and
sampling of media;
Five year reviews will be conducted.
Rank = 3
Same as Alternative 2A, with additional
long-term benefits from removal of COCs
in hot spots;
Potentially capable of destroying most
organic contaminants;
Metals contamination could be mobilized;
Contamination will remain in areas close to
containment barrier;
Oxidants and increased chlorides from
treatment could negatively impact
containment barrier and/or GETS;
Allows compliance with most identified
ARARs.
Rank = 4
Some modifications necessary to protect piezometers,
extraction wells, and monitor wells;
Might require treatment and disposal of 1 to 4 ft of soil from
cap area;
Requires pilot studies, compatibility testing and injection or
mixing of oxidants into soils;
Monitoring and O&M of cap required indefinitely;
Cannot be implemented close to the containment barrier and
potentially incompatible with GETS.
High to Very High
($31.6-$84.0 million)
Not retained because of
potential incompatibility with
IGR and high costs
Standard Chlorine of Delaware Site Feasibility Study Report
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County, Delaware
Table 4.2
Summary of Remedial Alternatives
for Standard Chlorine of Delaware Operable Unit 3
Page 3 of 4
General
Response Action
Alternative
Summary of Alternative
Effectiveness'1
Implementability0
Cost
Screening Conclusion
Treatment
Alternative
3A: ISTD with
SVE
ICs(2);
SVE recovery wells across entire 22.8 acre
former facility area and up to 1.4 acres of
Northern Area;
Soil is heated using radio frequency
heating, electrical resistance, thermal
conductance, hot air injection, or steam
injection;
Unheated SVE wells for locations within
10 ft of containment barrier;
Activated carbon treatment system to treat
recovered organic vapors not destroyed by
heating;
Security fencing to remain in place at least
until treatment is completed;
Periodic monitoring of site conditions and
sampling of media;
Five year reviews will be conducted.
Rank = 3
Potentially capable of destroying/removing
most SVOCs, VOCs, PCBs and dioxins;
Non-VOC contamination will remain in
areas adjacent to soil bentonite containment
barrier;
No treatment of inorganics;
Allows compliance with most ARARs.
Rank = 3
Same as Alternative 2C with additional effort for ISTD
construction and shorter O&M period for SVE;
Only unheated wells can be used within 10 ft of containment
barrier;
Reduces long term SVE carbon usage and SVE O&M
relative to Alternative 2C, but requires substantially higher
short term energy usage;
Very High
($124.2 - $162.2 million)
Not retained because of failure
to address risks related to
inorganic contaminants and
high costs
Treatment
Alternative 3B:
ISTD
Combined with
ISCO for
Select
Locations
ICs(2);
SVE recovery wells across entire 22.8 acre
former facility area and up to 1.4 acres of
Northern Area;
Soil is heated using radio frequency
heating, electrical resistance, thermal
conductance, hot air injection, or steam
injection;
Activated carbon treatment system to treat
recovered organic vapors not destroyed by
heating.
ISCO to treat areas recalcitrant to ISTD,
such as off-product/PCB concentration area
and portions of the former process area;
Security fencing to remain in place at least
until treatment is completed;
Periodic monitoring of site conditions and
sampling of media;
Five year reviews will be conducted.
Rank = 3
Potentially capable of destroying/removing
most SVOCs, VOCs, PCBs and dioxins;
Non-VOC contamination might remain in
areas adjacent to SB containment barrier;
No treatment of inorganics and could
mobilize metals contamination;
Allows compliance with most ARARs.
Rank = 4
Same as Alternative 3A with additional effort for ISCO
implementation;
Only unheated wells can be used within 10 ft of containment
barrier;
Potentially reduces temperature required for ISTD
Very High
($104.6-$151.8 million)
Not retained because of failure
to address risks related to
inorganic contaminants and
high costs
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Table 4.2
Summary of Remedial Alternatives
for Standard Chlorine of Delaware Operable Unit 3
Page 4 of 4
General
Response Action
Alternative
Summary of Alternative
Effectiveness'1
Implementability0
Cost
Screening Conclusion
Treatment
Alternative
3C. ISTD with
Excavation and
Off Site
Incineration of
Dioxin-
Contaminated
Soils
ICs(2);
SVE recovery wells across entire 22.8 acre
former facility area and up to 1.4 acres of
Northern Area;
Soil is heated using radio frequency
heating, electrical resistance, thermal
conductance, hot air injection, or steam
injection;
Activated carbon treatment system to treat
recovered organic vapors not destroyed by
heating;
Excavation, off-site transportation, and
incineration of dioxin-contaminated soils
with final disposal in an off-site landfill;
Security fencing to remain in place at least
until treatment is completed;
Periodic monitoring of site conditions and
sampling of media;
Five year reviews will be conducted.
Rank = 3
Potentially capable of destroying/removing
most SVOCs, VOCs, PCBs and dioxins;
Non-VOC contamination will remain in
areas adjacent to containment barrier;
No treatment of inorganics;
Allows compliance with most ARARs.
Rank = 4
Same effort for ISTD implementation as in Alternative 3A;
Lower electricity requirements than Alternative 3 A;
Additional effort for excavation and transportation of dioxin
soils to off-site incinerator facility with final disposal in off-
site landfill;
Only unheated wells can be used within 10 ft of containment
barrier;
Transportation of hazardous material could cause regulatory
and public relations issues;
Potential to spread contamination during transport.
Very High
($226.9 - $264.9 million)
Not retained because of failure
to address risks related to
inorganic contaminants and
high costs
Treatment
Alternative
3D. ISCO with
SVE Near the
Wall
ICs(2);
Application of Fenton's reagent throughout
the contaminated vadose zone except near
the containment barrier;
Unheated SVE wells for locations within
10 ft of containment barrier;
Activated carbon treatment system to treat
SVE off-gas;
Security fencing to remain in place at least
until treatment is completed;
Periodic monitoring of site conditions and
sampling of media;
Five year reviews will be conducted.
Rank = 3
Potentially capable of destroying/removing
most SVOCs, VOCs, PCBs and dioxins;
Non-VOC contamination will remain in
areas adjacent to containment barrier;
No treatment of inorganics and could
mobilize metals;
Allows compliance with most ARARs.
Rank = 4
Requires pilot studies, construction, O&M of SVE system;
Previous pilot studies for ISCO did not consider all of the
COCs and their associated PRGs;
Injection of large volume of liquid oxidants might require
modification of GETS, construction of a new treatment
system, and/or changes to NPDES Permit equivalence.
High to Very High
($25.8 million to $82.9 million)
Not retained because of failure
to address risks related to
inorganic contaminants and
high costs
Alternatives are ranked qualitatively on effectiveness and implementability, with 1 representing the most effective/implementable, and 5 representing the least effective/implementable.
ICs are part of Alternatives 2A-2D and 3A-3D. ICs include zoning ordinances, restrictive covenants and access agreements. Zoning ordinances will be applied to restrict uses of the property and/or limit site access to minimize exposure and protect site features. ICs to limit site use are required because the PRGs were
developed for a restricted land use scenario. Restrictive covenants can be included to require that vapor intrusion control features are installed for all new buildings constructed on site. Access agreements would be provided to ensure access for monitoring and maintenance of existing and planned remedial systems.
Surface cap will consist of a multilayer Subtitle C vegetated cap or a concrete/asphalt cap, and will be constructed over the entire portion of the On Facility area located within the containment barrier (22.8 acres). Depending on RD delineation of Northern Area, up to 1.4 additional acres will be included under the cap. The
cap will be tied into the existing groundwater containment barrier on three sides, and it will be equipped with soil gas capture system.
Potential treatment/disposal options for excavated soil include on site landfilling, ex situ LTTD/incineration, and ex-situ soil washing.
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5.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
This Section presents a detailed evaluation and comparison of the potential remedial
alternatives retained as a result of the screening process conducted in Section 4 of this FS
Report. In this Section, the nine CERCLA evaluation criteria are introduced, and each
alternative is described in detail and evaluated individually based on the CERCLA criteria. A
comparison of the remaining remedial alternatives based on their relative performance against
each of the evaluation criteria will be conducted in Section 6. Table 5.1 summarizes the results
of individual evaluation of the final alternatives.
5.1 EVALUATION CRITERIA
According to the EPA Guidance for Conducting Remedial Investigations and Feasibility
Studies Under CERCLA (RI/FS Guidance) (EPA, 1988), the detailed analysis of alternatives
should provide decision-makers with sufficient information to adequately compare the
alternatives, select an appropriate remedy, and demonstrate satisfaction of the CERCLA
remedy selection requirements in the ROD. Based on the RI/FS Guidance and in conformance
with the NCP, the alternatives will be compared based on the first seven of the following nine
evaluation criteria:
1) Overall protection of human health and the environment
2) Compliance with ARARs
3) Long-term effectiveness and permanence
4) Reduction of toxicity, mobility or volume
5) Short-term effectiveness
6) Implementability
7) Cost
8) State acceptance
9) Community acceptance
The first two of these criteria (overall protection of human health and the environment, and
compliance with ARARs) reflect statutory requirements to the ROD. These two criteria are
categorized as threshold criteria, because any alternative that is selected for implementation
must meet them. Criteria 3 through 7 are the balancing criteria used to compare retained
alternatives. The final two criteria (state or support agency acceptance and community
acceptance) are modifying criteria used to identify and address concerns of the state and
surrounding community. Modifying criteria are not evaluated in the FS, but are instead
addressed in the ROD based on comments received during the public comment period. Each of
the nine criteria, as it applies to OU-3, is briefly discussed below.
5.1.1 Overall Protection of Human Health and the Environment
All retained alternatives must achieve the overall protection of human health and the
environment. This evaluation criterion provides an overall assessment of each alternative's
ability to protect human health and the environment, focusing on how each alternative
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addresses site risks from each exposure pathway through treatment, engineering controls, or
ICs.
5.1.2 Compliance with Applicable or Relevant and Appropriate Requirements
The remedial alternatives are evaluated to determine whether they attain the ARARs that were
presented in Section 2.2. To be selected for implementation, an alternative must meet all
ARARs or have a justifiable reason why a waiver is appropriate.
In addition to the evaluation presented below, evaluation of each alternative with respect to
each of the relevant ARARs is summarized in Appendix B of this report.
5.1.3 Long-term Effectiveness and Permanence
This criterion evaluates the risk from untreated waste or treatment residuals remaining at the
conclusion of remedial activities. This evaluation takes into account contaminant volume,
toxicity, mobility, and propensity of the residuals to bioaccumulate. This analysis also includes
assessment of the uncertainties associated with an alternative for providing long-term
protection from wastes and residuals; the potential need to maintain or replace technical
components of the alternative; and the potential exposure pathways and risks posed should the
remedial action need replacement.
5.1.4 Reduction of Toxicity, Mobility or Volume
There is a statutory preference for remedies that permanently and significantly reduce toxicity,
mobility, or volume of the hazardous substances. This criterion is used to evaluate the
anticipated performance of the specific technologies an alternative may employ. The factors to
be considered include the extent to which total mass, volume, and/or mobility of contaminants
are reduced; the toxicity of residuals resulting from the remedy; and to what extent the effects
of treatment are irreversible.
5.1.5 Short-Term Effectiveness
This criterion is used to measure the effects of the various alternatives on human health and the
environment during implementation of the remedial action; as well as the effectiveness of the
proposed measures to protect the community, workers, and the environment.
5.1.6 Implementability
This criterion addresses the technical and administrative feasibility of implementing an
alternative, including the availability of services and materials required for its implementation,
the ease of construction and operation, monitoring considerations, the historical reliability of
selected technologies, and the ease with which the alternative can be integrated with other
remedial actions that might be necessary at the site.
5.1.7 Cost
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The total cost for the remedial action includes capital and O&M costs, both direct and indirect.
Capital costs consist of the direct costs for items such as labor, materials, equipment, and
services plus the indirect costs for engineering management, permits, startup, and
contingencies. A 15% contingency was utilized in all capital cost estimates for the alternatives.
O&M costs are the annual post-construction costs necessary to maintain the remedial action.
O&M costs include such items as operating labor, maintenance, auxiliary materials, and
energy.
A present worth analysis is used to evaluate expenditures that occur over different time periods
by discounting all future costs to a common base year. In accordance with EPA guidance,
present worth estimates are calculated at a 5% discount rate over 30 years (EPA, 2000), with
2008 as a base year.
The cost estimates in this report are order-of-magnitude level estimates, which are based on a
variety of information including quotes from suppliers, generic unit costs, vendor information,
conventional cost estimating guides, and professional judgment.
5.1.8 State Acceptance
This assessment evaluates issues and concerns the state might have regarding each of the
alternatives. State acceptance is not discussed in this analysis, because it will be addressed in
the ROD based on the state's comments on the FS Report and the Proposed Plan.
5.1.9 Community Acceptance
Community acceptance is evaluated based on issues and concerns the public may have
regarding each of the alternatives. This criterion will also be addressed in the ROD once public
comments on the Proposed Plan have been received.
5.2 DEFINITION AND INDIVIDUAL ANALYSIS OF ALTERNATIVES
In this section all the alternatives retained for detailed analysis are further defined and
evaluated based on the first seven evaluation criteria listed above. The following alternatives,
which were summarized in Table 4.1, were retained for detailed analysis:
• Alternative 1A: No Action
• Alternative 2A: Surface Cap
• Alternative 2B: Surface Cap with SVE
• Alternative 2C: Surface Cap with ISTD
5.2.1 Alternative 1A: No Action
5.2.1.1 Description
The no-action alternative is included as a baseline for comparison of other alternatives. No
remedial activities or ICs would be implemented under this alternative, although some level of
natural attenuation might occur. The performance of the no action alternative with respect to
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each of the seven evaluation criteria is discussed below:
5.2.1.2 Overall Protection of Human Health and the Environment
Because no action would be performed, this alternative would not protect human health or the
environment. Risks from soil and soil gas contamination at the site would not be significantly
different from those identified in the baseline risk assessment.
5.2.1.3 Compliance with ARARs
Because no action would be taken, the ARARs would not be met.
5.2.1.4 Long Term Effectiveness and Permanence
This alternative includes no controls for exposure and no long-term management measures. All
current and potential future risks would remain under this alternative.
5.2.1.5 Reduction in Toxicity, Mobility, or Volume
This alternative provides no significant reduction in toxicity, mobility, or volume of the
contaminants in site soils or soil gas.
5.2.1.6 Short Term Effectiveness
There would be no additional risks posed to the community, the workers, or the environment
as a result of this alternative being implemented.
5.2.1.7 Implementability
There are no implementability concerns posed by this remedy because no action would be
taken.
5.2.1.8 Cost
There are no projected costs associated with Alternative 1A.
5.2.2 Alternatives 2A, 2B, and 2C: Common Elements
With the exception of the No Action alternative, all of the proposed remedial alternatives
include some form of ICs in combination with other treatment or containment methods. The
proposed ICs include site use limitations that could be implemented through zoning ordinances,
restrictive covenants and access agreements, in combination with air monitoring program and
continued use and maintenance of the existing site fence and warning signs to restrict
unauthorized access to the Site. The ICs applicable to the OU-3 are described in Section 3.3.2
of this report. In addition, each of the remaining alternatives employs some form of a surface
cap to minimize precipitation infiltration, vapor intrusion risks, soil contact risks, and the
potential spread of soil contaminants. Alternative-specific differences in the implementation of
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these common elements will be discussed for each remedial alternative.
Because a substantial portion of the On Facility area is covered with reinforced concrete and
asphalt, demolition and disposal costs for these materials make up a significant portion of the
total costs associated with implementing each of these alternatives. If a cost-effective method
of grinding the concrete waste could be identified, then actual capital costs may be less than the
estimated values.
Although the Northern Area portion of OU-3 (or some part of it) could be included in each of
these alternatives, there is a lack of data showing what (if any) portions of this 1.4 acre area
would require remediation. As a result, costs related to the Northern Area portion of OU-3
are not included in the detailed costs presented in the following alternative descriptions.
However, it is expected that the costs for capping the entire Northern Area would range
between $430,000 and $827,000 depending on which type of cap was used. Costs for the
treatment components of Alternatives 2B and 2C were not estimated for the Northern Area
because the greater uncertainty associated with possible soil volumes requiring treatment
(anywhere between 0 and 111 ,000 cubic yards) would make the accuracy (and value) of any
such evaluation questionable.
5.2.3 Alternative 2A: Surface Cap
5.2.3.1 Description
This alternative includes construction of a concrete, asphalt, or multilayer surface cap (such as
RCRA Subtitle C cap), as described in Section 4.1.3.1. Air monitoring, security fencing, and
ICs (site use limitations that could be implemented through zoning, access agreements, and
restrictive covenants) described in that section are also a part of this alternative. The proposed
location and extent of the cap is shown in Figure 4.1. The surface cap would be tied into the
previously constructed vertical groundwater containment barrier on the west, south, and east
sides of the On-Facility Area. On the north side, the cap border would be the southern
boundary of the Northern Area, as shown in Figure 1.2. The approximate area to be covered
by the surface cap is 22.8 acres. If it is determined that some or all of the Northern Area
portion of OU-3 is contaminated at levels greater than the Off-Facility PRGs, the northern end
of the cap would be extended to incorporate those areas. Prior to the construction of the cap,
substantial quantities of concrete, asphalt, and subsurface utilities would have to demolished
and removed from the cap area.
Although all of the proposed cap alternatives would include multiple layers, the concrete and
asphalt cap options are somewhat simpler to construct. A soil-based multilayer cap would
typically include the following layers and is shown schematically in Figure 5.1:
• An upper vegetative topsoil layer (approximately 3 ft in thickness);
• A sand or geonet drainage layer;
• A geosynthetic FML;
• A low permeability barrier layer (approximately 2 feet of compacted clay and/or
geosynthetic clay with permeability not to exceed 10"7 cm/sec);
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• A gas extraction layer.
A concrete or asphalt cap would include the following layers, as shown schematically in Figure
5.2:
• Asphalt (wearing and binder courses) or concrete layer
• Crushed stone base layer
• Low permeability flexible membrane liner (FML);
• Gas extraction/venting layer.
One advantage of the concrete or asphalt cap is that it would more readily allow for installation
of additional extraction or monitoring wells if required in the future as compared to the multi-
layer cap. Details on the specific type, materials and thickness of the cap will be developed
during RD activities. The chosen surface cap type would depend on the intended use for the
site. Regardless of the cap type, subsurface and surface structures (i.e., piping, storm drains,
utilities, extraction well vaults, concrete containment pads, demolition debris) and mature
vegetation would need to be removed prior to cap construction. This demolition debris would
be sampled to determine whether it can be sent off site for disposal in a nonhazardous waste
landfill or recycled. Debris that is determined to be hazardous would likely be decontaminated
and disposed of off site or ground up and incorporated into the soils in the area to be capped.
To ensure cap integrity, the cap and the area around it would be graded to divert surface runoff
to the east and west stormwater basins or other stormwater management features that would be
built during the cap construction. The stormwater control system would be designed to allow
for integration of the cap into the adjacent ecosystems. The area to be capped would have to
be compacted (using vibratory rollers or another standard compaction device) to provide
proper structural cap support. As discussed earlier, it is possible cap construction would
require the excavation of 37,000 cubic yards to 156,000 cubic yards of soil. Although various
options of treating and disposing of these soils were presented in Section 4.1.4, the most cost-
effective method of dealing with these materials would be to reintegrate them into the area to
be capped. To minimize the potential for these materials to cause structural problems with the
completed cap, they should be screened prior to being placed back in the facility area. If these
excavated soils cannot be reintegrated into the soils under the cap, they would need to be
treated or disposed using one of the treatment or disposal options introduced in Section 4.1.4.
Depending on the type of cap employed, the capped area could be available for compatible
land uses including park land, naturalized open space, warehousing, storage facilities, or other
low occupancy (as defined in 40 CFR 761.3) facilities. Performance of Alternative 2A with
respect to the seven CERCLA evaluation criteria is discussed below.
5.2.3.2 Overall Protection of Human Health and the Environment
The surface cap alternative would adequately protect human health and the environment by
minimizing human and wildlife contact with contaminants in soil and soil gas. If implemented
and maintained properly, Alternative 2 would virtually eliminate all exposure pathways
identified in the BLRA for human and ecological exposure. Surface cap, in combination with
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the ongoing groundwater remedy, would also minimize spread of contamination out of the
capped area by reducing infiltration, decreasing volatile and fugitive dust emissions, and
isolating contaminants from surface water runoff. The existing GETS would prevent spread of
contamination from the capped area via the groundwater pathway.
5.2.3.3 Compliance with ARARs
Compliance of Alternative 2A with the relevant ARARs is summarized in Appendix B and
briefly discussed below.
Although Alternative 2A would not reduce the contaminant concentrations, it would meet the
chemical-specific ARARs for soil and soil gas (expressed as the risk-based PRGs in Table 2.2
and 2.3) by preventing or limiting human and ecological exposure to contaminated soil and soil
gas. Installation of a surface cap would also reduce or eliminate the potential for contaminants
to migrate from facility soils to groundwater, air, sediments, and off site soils. ICs such as
restrictive covenants and zoning ordinances would further minimize the potential for future
exposure.
Air emissions generated by potential treatment and disposal of the soil excavated during cap
construction, other excavation or soil moving activities, and the vapor collection system would
need to comply with Clean Air Act and the Delaware State Implementation Plan. The types
and frequency of air monitoring activities necessary to meet these requirements will be
finalized during the RD activities. Dust suppression measures would be employed during
surface cap construction activities to ensure that emissions are minimized to meet the
requirements of these regulations.
Solid waste and waste residuals (such as spent carbon) generated by the vapor collection and
treatment system, and, potentially, from treatment of any excavated soils, would be
categorized and disposed in compliance with the RCRA, as amended in 42 USC §§6901 et seq,
the associated RCRA regulations, and the DRGHW.
Any liquid wastes generated during the cap construction would be treated in the GETS so that
they meet that system's NPDES permit equivalence (which takes into account the Clean Water
Act, the Delaware Regulations Governing the Control of Water, and the State of Delaware
Surface Water Quality Standards). Construction and other activities impacting stormwater or
water quality in the nearby wetlands would also comply with these regulations by utilizing
existing and constructing new stormwater management features as needed.
Once constructed and stabilized, the surface cap alternative would reduce the mobility of
contaminated surface soils which might otherwise migrate off site and impact the wetlands
located on the east and west sides of the site. This reduction in sediment discharge would meet
the requirements of the EPA Protection of Wetlands Regulations. Through the use of, and
addition to, existing sediment and erosion controls, the wetlands would also be protected
during cap construction activities.
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Because the site is located within the Delaware coastal zone, all construction and other
activities would comply with Delaware's coastal zone management program. Zoning
ordinances and restrictive covenants would stipulate that the site may not be used for heavy
industry in the future.
Construction of a surface cap to minimize exposure to, and migration of, site contaminants
would be consistent with the DRGSHW and RCRA landfill closure requirements, as well as
the DRGHSC. Requiring that the surface cap have a permeability of less than 10~7 cm/sec and
incorporating the features of a RCRA Type C Cap (depicted in the schematic shown in Figure
5.1) would ensure compliance with these regulations. The requirement to construct a liner
system, however, will not be met. Instead, any cap that is constructed will be tied into the soil
bentonite containment barrier that was installed as part of the IGR. This barrier is keyed into a
low permeability layer that lies between the contaminated soils of the Columbia Formation and
the underlying drinking water aquifer (the Potomac). This method of construction will isolate
any contaminated OU-3 soils left under the cap from surrounding uncontaminated areas. This
alternative will attain a standard of performance that is equivalent to the standard that would be
attained through the construction of a liner system. As a result, this ARAR will be waived in
accordance with 40 CFR § 300.430(f)(l)(ii)(C)(4).
Under Alternative 2A, soil and soil gas contaminants would remain in OU-3 soils. The
alternative would therefore fail to meet the PRGs that were developed to meet the required 10~5
risk level required by the DRGHSC. However, the surface cap would achieve the 10~5 risk
level eliminating the soil contact route of exposure and severely limiting the possible exposure
to contaminants in soil gas.
All liquid or solid waste generated during site activities would be categorized, handled, and
disposed of in accordance with the RCRA and DRGSHW requirements. Depending on the
method used to deal with soils excavated during the construction of the surface cap, several of
the RCRA and DRGSHW sections would be applicable to the selected remedy (as discussed in
Section 2.2).
None of the soil samples collected from the OU-3 areas had PCB concentrations greater than
the 25 parts per million cleanup level specified for the "low occupancy areas". The bulk of
these analyses were performed using the EPA Method 8081 that is specified in the TSCA
regulations. Data collected from the wetlands area suggest that use of EPA Method 8081 may
underestimate the actual presence of PCBs in the site soil. The available PCB data indicate
that containment through the use of a surface cap would meet the remedial requirements listed
in TSCA as long as the facility is classified as a "low occupancy area" as defined in 40 CFR
761.3. The use of restrictive covenants to ensure this classification is maintained and the
inclusion of deed notifications detailing the presence of PCB contamination on site would allow
a surface cap to meet the requirements of the TSCA detailed in Section 2.2. Installation of a
surface cap would be compliant with the TSCA as long as site soils have PCB concentrations
of 100 mg/kg or less.
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To meet the DSWA prohibitions on the disposal of wastes from Superfund sites, demolition
debris and other wastes that require offsite disposal would be shipped out of state to permitted
disposal or recycling facilities.
Because over 5,000 square feet of land would be disturbed during the cap construction under
this alternative, the substantive requirements of the Delaware Stormwater and Sediment
regulations will be met.
To comply with the Delaware Air Quality Management Regulations, dust suppression
measures would be utilized. Additionally, treatment (most likely using carbon adsorption) and
permitting of emissions from the cap's soil gas collection system would be necessary if it is
determined that more than 15 pounds of pollutants would be emitted per day.
Any construction, modification, and abandonment of monitoring wells, extraction wells or
piezometers would be performed in accordance with Delaware Regulations Governing the
Construction and Use of Wells, as well as Delaware's statute regarding Licensing of Water
Well Contractors, Pump Installer Contractors, Drillers, Pump Installers, Septic Tank
Installers, Liquid Waste Treatment Plant Operators and Liquid Waste Haulers..
5.2.3.4 Long-Term Effectiveness and Permanence
The cap is expected to be effective and reliable over the long term if properly designed and
maintained. Surface caps can be damaged by such mechanisms as erosion, soil settling,
maintenance activities, and burrowing animals. Because the contaminated soil would remain
onsite, long-term monitoring, maintenance, and control would be required under this
alternative. A review would be conducted at least every 5 years to ensure that the remedy
continues to provide adequate protection of human health and the environment in accordance
with CERCLA 121(c).
Future construction activities and site use would be restricted to protect the integrity of the cap
through the use of ICs that would remain in place over the long term. Because stormwater
would continue to infiltrate through the areas to the north of the cap and could raise
groundwater elevation to the point that groundwater comes in contact with the residual
contamination, this alternative requires that the GETS or some other groundwater
control/treatment system be operated for the foreseeable future.
5.2.3.5 Reduction of Toxicity, Mobility or Volume
This alternative would reduce the mobility of the contaminants through decreasing migration
via air blown soil particles, surface runoff, seepage into groundwater, and escape of the soil
gases into the atmosphere. Toxicity and volume of the contaminated soil within the capped area
would not change significantly under this alternative, with the possible exception of
contaminants found in any soils that are removed during the construction activities. These soils
would be treated and disposed of if they can not be reintegrated into the soils underlying the
capped area. Human and wildlife exposure to the toxicity would be minimized as long as the
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cap is intact. It is estimated that 906,500 cubic yards of soil contaminated above the PRGs
would remain under the cap.
5.2.3.6 Short-Term Effectiveness
Construction of a surface cap would take approximately 4 to 8 months. There is a substantial
risk that construction workers would be exposed to the contaminants in surface soil and soil
gas during the associated grading and excavation activities. Some small increase in the risk to
the surrounding community and ecosystems might also occur as contaminated soils are
disturbed during excavation and construction activities. The potential for these short-term risks
would be minimized through the use of dust control technologies such as water or foam sprays,
appropriate training, fugitive emissions monitoring, and use of personal protection equipment
for construction workers. Temporary decontamination pads would be required to minimize the
potential for the spread of contamination from excavation areas.
5.2.3.7 Implementability
A surface cap can be constructed at the site using standard road construction equipment and
readily available materials and labor. No major technical difficulties are anticipated in
implementing this alternative. The security fence that surrounds the facility portion of the OU-
3 area would be left in place, although the northern end of the fence line might need to be
extended to include the Northern Area.
Additional site preparation would be required for cap construction because of subsurface and
surface structures. Care must be taken during construction activities to avoid damaging the
previously installed containment barrier and other IGR components (including piezometers,
monitoring wells, and extraction wells). The appropriate air emission approvals may be
required prior to the start of work.
Long-term administrative resources would be required to ensure enforcement of the ICs,
maintenance of the cap, and conducting of the 5-year reviews. Implementation of additional
actions, if required, could be complicated by the need to preserve the cap. Chemically and
physically intrusive activities conducted as part of further remedial actions might need to be
prohibited or conducted under more restrictive conditions. Alternatively, removal of portions
of the cap (with subsequent reinstallation/patching) might be necessary before additional
intrusive remedial actions could be implemented. Finally, construction of a multilayer,
concrete, or asphalt cap would limit future uses of the site. In all likelihood, the previously
mentioned "low occupancy" restriction would eliminate most commercial uses of the site
although storage units, warehousing facilities, and other similar operations might be
acceptable.
5.2.3.8 Cost
This section presents the present worth analysis for the three different types of caps.
Uncertainties that could impact the total cost of this alternative include: the number and
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locations of subsurface obstructions that would require removal prior to installation of the cap;
the type of cap to be installed; the potential for damage to the existing monitor wells and
extraction wells during construction; and the aforementioned lack of data for the Northern
Area. Capital and O&M costs for the surface cap portion of this remedy would be impacted by
the type of cap selected. As a result, estimates are presented for each of the surface cap types
under consideration. The cost calculations for Alternative 2A are presented in Appendix C-l.
• The capital cost for Alternative 2A is estimated to be
0 Multilayer Cap $17.5 Million
0 Concrete Cap $17.2 Million
0 Asphalt Cap $11.1 Million.
• The present worth O&M cost would be approximately
0 Multilayer Cap $949,000
0 Concrete Cap $255,000
0 Asphalt Cap $557,000.
• The total project cost (present worth) is estimated to be
0 Multilayer Cap $18.5 Million
0 Concrete Cap $17.5 Million
0 Asphalt Cap $11.6 Million.
5.2.4 Alternative 2B: Surface Cap with Soil Vapor Extraction
In this alternative, the surface cap in Alternative 2A would be supplemented with an in-situ
SVE system, as described in Section 4.1.3.2. SVE wells would be placed at some or all of the
"hot spots" identified in Section 1.5.1. The SVE system would be operated to treat VOCs
under the cap until the limitation of technology is reached (i.e. the concentration of COCs in
the off gas remains very low). VOC extraction concentrations would be monitored weekly for
two months and monthly thereafter for two years or until no significant VOC removal is being
achieved. After this time, the SVE wells would be sealed to provide for cap homogeneity. No
thermal enhancement/soil heating would be used with the SVE in this alternative.
Although the detailed design of the SVE system would be developed during the RD phase, it is
expected that the SVE system would consist of a series of air extraction and inlet wells
approximately 50 feet deep, connected to a vacuum extraction and treatment system through a
network of manifolds and equipped with valves to allow flexibility of operation. The wells
would likely be screened across the bottom 20 feet to facilitate movement of gas through the
soils. Sample ports would be provided to allow monitoring of the extracted soil vapor as well
as in-situ conditions.
The SVE system would likely include a programmable-logic based control system. The area
for SVE implementation is anticipated to require the use of several hundred SVE wells, and
these wells would be connected with main headers to a central treatment area. The control
system would actuate valves on main headers to allow extraction from one group of SVE wells
at time, thereby decreasing the size of process components and electrical power requirements.
This approach would mimic 'pulsed' operation of the different remediation areas, and is
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expected to achieve cleanup in a sufficient timeframe.
Because off gas from the SVE system would contain substantial levels of contamination, the
system may need to comply with the substantive provisions of the permit equivalence. In
accordance with the expected requirements of this permit equivalence, off-gas from the SVE
system would need to be treated before discharging it to the atmosphere. Among the
technologies that could be employed to achieve treatment are carbon adsorption and
condensation. Because the diversity of contaminants would complicate the management of
condensates, a vapor phase activated carbon adsorption system with pretreatment for moisture
removal would most likely be the best suited treatment alternative. The spent carbon would be
regenerated (either on site or off site) for reuse or disposed of off site.
Based on the systems at other sites and the soil conditions at OU-3, radii of influence on the
order of 15-25 feet are expected. Material, radius of influence and location for the
injection/extraction wells will be finalized in the RD stage, based on the results of the pilot
studies. If in situ SVE is to be implemented as a part of the final alternative, more extensive
sampling would be beneficial to further delineate the contaminated areas requiring treatment.
5.2.4.1 Overall Protection of Human Health and the Environment
This alternative provides overall protection of human health and the environment both through
minimizing contact with the contaminants and limiting contaminant mobility (surface cap) and
through removing some of the VOC contamination (SVE). Total risks from the site would
decrease following the completion of the SVE treatment.
5.2.4.2 Compliance with ARARs
As shown in Appendix B, Alternative 2B is expected to comply with its relevant ARARs. In
addition to compliance with the ARARs identified for the surface cap alternative (Alternative
2A), construction of the SVE wells would be performed in accordance with the Delaware
Regulations Governing the Construction and Use of Wells, as well as Delaware's statute
regarding Licensing of Water Well Contractors, Pump Installer Contractors, Drillers, Pump
Installers, Septic Tank Installers, Liquid Waste Treatment Plant Operators and Liquid Waste
Haulers.
Additionally, the substantive provisions of permitting requirements and off gas treatment
requirements would likely have to be met to achieve compliance with federal and state air
quality regulations during implementation of this alternative. These additional measures would
be required if more than 15 Ib/day of pollutants are generated by the SVE system. Monitoring
and sampling of the SVE system would be required to ensure compliance with the substantive
air permit requirements.
5.2.4.3 Long-term Effectiveness and Permanence
The SVE portion of this alternative is expected to decrease permanently the VOC
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concentrations in soil and soil gas. Decreased VOC concentrations would permanently reduce
the overall risk associated with the soil and soil gas beneath the cap. The cap portion of this
alternative would control residual risks by minimizing human and wildlife exposure to the OU-
3 soil and soil gas. The decrease in VOC contaminant mass would also reduce permanently
the potential for the volatile COCs to migrate via the soil-to-air and soil-to-groundwater
pathways.
As described for Alternative 2A, surface cap maintenance activities would need to continue
indefinitely. ICs would remain in place for protection of the GETS and the surface cap. The
operational time of the GETS might be shortened after implementation of this alternative
because the SVE system would decrease the total mass of VOCs available for leaching from
the soil into the groundwater. It is expected that the SVE system would operate for two years.
O&M activities would include maintaining and repairing blowers, replacing activated carbon
(if used for off-gas treatment), and preventing fouling of the extraction wells.
5.2.4.4 Reduction of Toxicity, Mobility or Volume
The surface cap would reduce mobility of the contaminants through decreasing migration via
air-blown soil particles, surface runoff, seepage into groundwater; and escape of soil gases into
the atmosphere. Operation of the SVE system would decrease the mass of VOCs present at
OU-3. The contamination would be transferred to the activated carbon. Regeneration of the
activated carbon would result in contaminant destruction. Pilot studies would be necessary to
better estimate the expected extent of VOC removal and remaining contaminant concentrations
at the site.
5.2.4.5 Short-Term Effectiveness
Short-term risks and mitigation measures related to the construction activities for the surface
cap would be the same as described for Alternative 2A. Care would be taken to ensure that
additional risks resulting from the construction and utilization of the SVE system are
controlled. These measures would include monitoring of the treated vapor before it is released
into the atmosphere, as well as proper treatment and disposal of the spent activated carbon,
condensates, or other concentrated wastes.
Surface cap and SVE well construction, including pilot study activities, are expected to be
completed in approximately 1 to 2 years. Operation of SVE system is expected to last two
years following system construction.
5.2.4.6 Implementability
Surface cap construction in Alternative 2B would be somewhat complicated by the need to
allow for the SVE system extraction/injection wells. However, the two components are
compatible and can be implemented with standard construction methods and equipment. One
approach that would improve the constructability of the cap would be to install the SVE system
first using manifolds to connect the SVE wells to horizontal conveyance piping laid in trenches
U.S. EPA Region 3
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installed into the pre-cap ground surface. After the trenches are filled in and compacted, the
cap can be constructed with the SVE system in place. This approach would eliminate the
drawbacks related to having hundreds of wells penetrating the surface cap and potentially
providing pathways for volatile compounds to migrate to the air and for precipitation to
infiltrate. If greater air flux is required to achieve effective treatment in certain portions of the
site, additional inlet wells could be installed through the cap. After the SVE system is shut
down, these wells would have to be abandoned in accordance with DNREC requirements, and
the cap repaired in the areas of penetration.
The corrosive nature of the soils and groundwater (from probable releases of hydrochloric acid
at the SCD facility and the sulfuric acid spill that occurred at the former Motiva refinery) could
cause operational problems for the SVE system if carbon steel is used for well casings and
screens. Incompatibilities between the many of the COCs and plastics such as high density
polyethylene (HDPE) might dictate the use of stainless steel for casing and screen. Final
material selection will be made as part of the RD process, but pilot testing and material
compatibility would help determine whether the wells and conveyance piping can be made of
low-cost HDPE or if stainless steel or carbon steel must be used.
Technical feasibility of this treatment technology for the on-facility area at the SCD site is
improved by the lowered water table and sandy soils. SVE technology has been identified by
USEPA as a presumptive remedy for sites with soils contaminated by VOCs (EPA, 1993).
Collection of confirmatory samples of SVE performance would be complicated if the surface
cap is installed prior to the completion of SVE system operation, but the cap would increase
the effectiveness of the SVE system by reducing the potential for short circuiting.
5.2.4.7 Cost
The cost estimate for the cap portion of this alternative is affected by the same uncertainties
identified for Alternative 2A. Because of the relatively short system lifespan (approximately
two years) and the expected dilution of vapor concentrations in the SVE system, HDPE piping
was assumed for development of this cost estimate. If it is determined during pilot testing or
material compatibility testing that stainless steel casing and screen would be required, the costs
associated with the construction of the SVE system would be substantially higher. Another
uncertainty in the SVE cost estimate is radius of influence that would be achieved by the SVE
wells. This cost estimate was based on an assumed radius of influence of 18 feet. Electrical
costs were calculated based on a rate of $0.12/kilowatt-hour. The cost calculations for the
SVE portion of Alternative 2B are presented in Appendix C-2.
• The capital cost for Alternative 2B is estimated to be
0 Multilayer Cap $24.3 Million
0 Concrete Cap $24.0 Million
0 Asphalt Cap $17.8 Million.
• The present worth of O&M costs would be approximately
0 Multilayer Cap $1,855,000
0 Concrete Cap $1,161,000
0 Asphalt Cap $1,336,000.
U.S. EPA Region 3
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• The total project cost (present worth) is estimated to be
0 Multilayer Cap $26.2 Million
0 Concrete Cap $25.2 Million
0 Asphalt Cap $19.1 Million.
5.2.5 Alternative 2C: Surface Cap with In Situ Thermal Desorption
5.2.5.1 Description
Alternative 2C includes all the elements of Alternative 2B (Surface Cap and SVE) with the
main difference being that the "hot spot" soils would be heated to facilitate volatilization and
removal of SVOCs, PCBs, and dioxins. Alternative 2C includes the following components:
• Further sampling to delineate contamination;
• ISTD of "hot spot" areas more than 10 feet away from the containment barrier;
• Unenhanced SVE for areas within 10 feet of the containment barrier;
• Treatment of collected soil vapor as presented in Alternative 2B;
• ICs as described in Section 4.1.3;
• Confirmatory sampling during and following operation of the ISTD system;
• Construction of Surface Cap as presented in Alternative 2A.
Based on discussions with ISTD vendors, it is estimated that ISTD heaters and vapor extraction
wells would be placed between 8 and 12 ft apart over the 330,000 square feet area that
comprises the "hot spots" in the site. Based on heater spacing and the area being addressed, it
is projected that a total of 2,800 heaters and 1,400 extraction wells would be installed on site.
In the event that the Northern Area is determined to be a "hot spot" in need of treatment in
addition to capping, approximately 500 additional heaters and 250 additional extraction wells
would be installed to address the 60,000 square feet area.
The heaters and extraction wells would extend through the 50 ft vadose zone to heat the soil to
temperatures close to or above the boiling points of the soil contaminants. It is expected that
temperatures in excess of 570 to 650°F would be required to facilitate volatilization of most of
OU-3 organic COCs. These temperatures should be achieved using the aforementioned
spacing. The volatilized organics would then be extracted through an SVE system similar to
that described in Alternative 2B.
Soil heating for ISTD can be achieved by several methods, including hot air or steam injection,
radio-frequency heating, electrical resistance heating, and thermal conduction heating. The
method to be used at OU-3, as well as the actual well and heater spacing, would be determined
during the RD stage based on site-specific data including soil bulk density, soil moisture
content, VOC distribution, implementation costs, and results from pilot studies.
The ISTD system in Alternative 2C would differ from the SVE system in Alternative 2B in a
number of ways. Extraction and heater wells for the ISTD system would need to be
constructed from heat-resistant material (likely stainless steel). Because of the number of wells
that would penetrate any cap and the difficulties that would be encountered if construction of a
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cap were attempted with the wells already in place, it is expected that the surface cap would
not be installed until the ISTD process is complete and the well casings have been removed.
5.2.5.2 Overall Protection of Human Health and the Environment
The ISTD system would substantially reduce the concentrations of organic soil and soil gas
contaminants in the areas identified as "hot spots" on the facility portion of the site, and, if
necessary, the Northern Area. By reducing organic COC concentrations of the most
contaminated areas, contaminant migration and potential risks from chemical exposures would
be decreased. The risks associated with the residual COCs would be addressed through
completion of the surface cap that would prevent exposure by human and ecological receptors.
Additionally, the cap would minimize precipitation infiltration, and in doing so substantially
limit the potential for contamination to be spread via the soil to groundwater pathway. The
soil to sediment migration pathway would be eliminated because the cap would prevent the
contact of stormwater run off with site contaminants. The use of an integrated soil gas capture
and treatment system would minimize the potential risks related to soil gas and contaminant
migration via the soil to air pathway. Finally, ICs would further limit the potential future risks
from vapor intrusion and soil contact by requiring that countermeasures be incorporated into
any building that is built on affected portions of the site and establishing restrictions on future
construction activities.
5.2.5.3 Compliance with ARARs
Alternative 2C is expected to comply with the relevant ARARs. In addition to compliance with
the ARARs identified for the surface cap alternative (Alternative 2A), and the surface cap with
SVE alternative (Alternative 2B), the surface cap with ISTD approach is expected to comply
with the following regulations and requirements.
As stated in Alternative 2A, cap construction, maintenance, and closure would follow RCRA
requirements for a Type C Landfill cap, except that a liner system will not be constructed.
Because the heating of soils in the "hot spot" areas would increase the volatilization of the site
contaminants, it is likely that compliance with the substantive provisions of permit
requirements and off gas treatment would be required. Treatment of the off gas in accordance
with the relevant air regulations would be achieved through the use of carbon adsorption or an
oxidizer.
5.2.5.4 Long-term Effectiveness and Permanence
ISTD is expected to remove sufficient quantities of organic contaminants from soil and soil gas
to lower the concentrations of these contaminants below their respective PRGs in the "hot
spot" portions of the facility. This contaminant removal would result in a permanent reduction
in risk to human and ecological receptors, and a permanent reduction in the total contaminant
mass available for migration via the soil-to-air, soil-to-groundwater, and surface water run off
pathways. Organic contaminants in other portions of OU-3 and inorganic contaminants
U.S. EPA Region 3
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throughout OU-3 would be unaffected by the ISTD system. To ensure that the surface cap
effectively prevents exposure to this residual contamination, long-term monitoring,
maintenance, and control would be required under this alternative. If properly designed,
constructed, and maintained, the surface cap would provide an effective long-term remedy. A
review would be conducted at least every 5 years to ensure that the remedy continues to
provide adequate protection of human health and the environment in accordance with CERCLA
5.2.5.5 Reduction of Toxicity, Mobility or Volume
As with Alternatives 2A and 2B, the surface cap would reduce the mobility of the contaminants
via air-blown soil particles, surface runoff, seepage into groundwater, or escape of soil gases
into the atmosphere. A higher degree of reduction in contaminant toxicity, mobility and
volume is expected from this alternative as compared to Alternative 2A and 2B due to the
increased COC removal associated with ISTD. The ISTD system would permanently remove
VOCs, SVOCs, PAHs, PCBs, and dioxins from the soils and, in the case of VOCs and some
SVOCs, soil gas. The compounds captured by the gas collection system would be destroyed
either within the oxidizer or through regeneration of the spent carbon, depending on the
treatment approach selected for the off-gas. The COCs likely to remain after treatment
(including inorganics) are expected to be non-volatile and relatively immobile.
5.2.5.6 Short-term effectiveness
Short-term risks and mitigation measures related to the construction activities for the surface
cap would be the same as described for Alternative 2A. The potential short-term risks during
ISTD implementation are similar to those described for SVE. These risks would be mitigated
through control of emissions from the off-gas treatment unit, air monitoring, use of PPE by
workers, and implementation of engineering controls. Treatment of the "hot spots" is
expected to take less than one year to complete. Construction of the surface cap is expected to
require 4 to 8 months.
5.2.5.7 Implementability
ISTD technology is fully developed and has been applied at Superfund sites. Steam heating of
the contaminated soils would not provide the temperatures necessary to volatilize the COCs
from the identified "hot spots". As a result it is more likely that some form of electrical
heating would be required. Electricity and water for soil heating and treatment is available on
site although a higher wattage electrical supply would likely be required. Natural gas (which
might be needed for the ISTD) would be available from a main that runs along Governor Lea
Road.
While an SVE system could be integrated under the surface cap by connecting the vertical
extraction wells to horizontal conveyance piping that channel the extracted vapors to an off gas
treatment system, it would not be practical to route all of the wiring for approximately 4,200
heating elements under the cap. Attempting to install the ISTD system after construction of the
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cap would severely reduce the effectiveness of the cap. Additionally, the heating of the ISTD
could damage the surface cap if operated after the cap's construction. Consequently, although
the timing and sequencing of the remedy will be finalized during the RD, it is expected that
ISTD would occur following the removal of the demolition debris but before the construction
of the surface cap.
Materials used in the construction of the ISTD system must be able to withstand the heat
generated by the system. Consequently, neither PVC nor HOPE can be used in the
construction of the ISTD wells. Furthermore, the corrosive nature of the soils and
groundwater (from probable releases of hydrochloric acid at the SCO facility and the sulfuric
acid spill that occurred at the former Motiva refinery) could also result in operational problems
for the ISTD system unless proper materials are selected. Well casings and heating elements
would likely be made of stainless steel, although final material selection will be performed as
part of the RD process.
Pilot studies will be necessary to optimize well placement and gain a better understanding of
the extent of contaminant removal that can be expected. Additional characterization sampling
would be helpful to further delineate those areas that would benefit most from the application
of ISTD before the installation of a surface cap.
5.2.5.8 Cost
Because ISTD treatment should be completed within the first year, costs related to the ISTD
system's O&M and removal have been included in the capital costs for this alternative. Capital
and O&M costs for the surface cap should be equal to those observed in Alternatives 2A. In
addition to the cost uncertainties identified for Alternative 2A, issues that could impact the total
cost of this alternative include potential increases in electrical costs, and the material required
for the well casings and heating elements. Electrical costs were calculated using a rate of
$0.12/kilowatt-hour. The cost calculations for Alternative 2C are presented in Appendix C-3.
• The capital cost for Alternative 2C is estimated to be
0 Multilayer Cap $98.8 Million
0 Concrete Cap $98.3 Million
0 Asphalt Cap $92.4 Million.
• The present worth O&M cost would be approximately
0 Multilayer Cap $949,000
0 Concrete Cap $255,000
0 Asphalt Cap $557,000.
• The total project cost (present worth) is estimated to be
0 Multilayer Cap $99.8 Million
0 Concrete Cap $98.6 Million
0 Asphalt Cap $92.8 Million.
U.S. EPA Region 3
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TABLE
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Table 5.1
Individual Evaluation of Remedial Alternatives
for Standard Chlorine of Delaware Operable Unit 3
Page 1 of 7
Criteria
1. OVERALL PROTECTIVENESS
Human Health Protection
Soil: direct contact/inhalation/
ingestion
No significant
reduction in
risk.
Contamination
would remain
above the target
risk levels.
Cap would reduce risk from contact,
inhalation and digestion of soil to below
target risk level
See Alternative 2A;
SVE would reduce VOCs
and some SVOCs in vadose
zone soils in "hot spot"
areas reducing risks for
future construction workers
See Alternative 2A;
ISTD would reduce or
eliminate organic
contaminants from vadose
zone soils in "hot spot" areas
reducing risks for future
construction workers
Soil gas inhalation
No significant
reduction in
risk.
Contamination
would remain
above the target
risk levels.
Cap equipped with a gas collection system
would reduce risk from soil gas to below
target risk level
See Alternative 2A;
SVE would reduce VOCs
and SVOCs in "hot spot"
area soil gas
See Alternative 2A;
ISTD would reduce organic
contaminants in "hot spot"
area soil gas
Contact with contaminated
surface or ground water
No significant
reduction in
risk.
Contamination
would remain
above the target
risk levels.
Cap would eliminate stormwater contact
with contaminated soil and minimize
precipitation infiltration thereby reducing
health risks
See Alternative 2A;
SVE would reduce or
eliminate VOCs from
vadose zone soils in "hot
spot" areas reducing
potential spread of
contaminants to
groundwater
See Alternative 2A;
ISTD would reduce or
eliminate organic
contaminants from vadose
zone soils in "hot spot" areas
reducing potential spread of
contaminants to groundwater
Environmental Protection
No significant
reduction in
risk.
Contamination
would remain
above the target
risk levels.
Surface cap would reduce risk from
contact, inhalation and digestion of soil and
soil gas to below target risk levels by
preventing or minimizing exposure.
See Alternative 2A
Same as Alternative 2A
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Table 5.1
Individual Evaluation of Remedial Alternatives
for Standard Chlorine of Delaware Operable Unit 3
Page 2 of 7
2. COMPLIANCE WITH ARARs
Does Alternative Comply with
ARARs?
Does not meet
ARARs for soil
and soil gas
Construction of a surface cap to minimize
exposure to, and migration of, site
contaminants would be consistent with the
DRGSHW and RCRA landfill closure
requirements, as well as the DRGHSC.
Requiring that the surface cap have a
permeability of less than 107 cm/sec and
incorporating the features of a RCRA Type
C Cap would ensure compliance with these
regulations. The requirement to construct a
liner system, however, will not be met.
Instead, any cap that is constructed will be
tied into the soil bentonite containment
barrier that was installed as part of the
IGR. This barrier is keyed into a low
permeability layer that lies between the
contaminated soils of the Columbia
Formation and the underlying drinking
water aquifer (the Potomac). This method
of construction will isolate any
contaminated OU-3 soils left under the cap
from surrounding uncontaminated areas.
This alternative will attain a standard of
performance that is equivalent to the
standard that would be attained through the
construction of a liner system. As a result,
this ARAR will be waived in accordance
with 40 CFR § 300.430(f)(l)(ii)(c)(4).
Otherwise, the Alternative is expected to
comply with the all identified ARARs
See Alternative 2A
See Alternative 2A
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Table 5.1
Individual Evaluation of Remedial Alternatives
for Standard Chlorine of Delaware Operable Unit 3
Page 3 of 7
3. LONG-TERM EFFECTIVENESS AND PERMANENCE
Magnitude of residual risk;
adequacy and reliability of
controls; need of 5-year review
Existing risk
would remain.
Contaminants
would continue
to migrate to
the surface
water, infiltrate
into deeper soil
and
groundwater,
and be
transported via
airborne soil
particles.
Risks from direct contact, soil ingestion,
and soil gas inhalation would be reduced/
eliminated as long as cap integrity is
maintained.
Surface cap would prevent precipitation
infiltration, reduce the potential for further
groundwater contamination and would
reduce volume of groundwater requiring
treatment by GETS.
See Alternative 2A.
Removal of VOCs from
some areas by SVE would
reduce contamination
remaining under the cap.
Metals and most organic
contamination would
remain.
See Alternative 2A.
Removal of organics from
some areas by ISTD would
reduce contamination
remaining under the cap.
Metals contamination would
remain; VOCs, SVOCs,
dioxin, pesticide, and PCB
contamination would remain
in some areas.
Magnitude of residual risk;
adequacy and reliability of
controls; need of 5-year review
(continued)
Five year
reviews
required
indefinitely.
Contaminants would not be removed
except through soil gas collection system.
Five year reviews, cap maintenance,
institutional controls and GETS operation
would be required indefinitely.
Five year reviews, cap
maintenance, institutional
controls would be required
indefinitely.
Some form of groundwater
extraction and treatment
would be required
indefinitely,
GETS operational costs
might be reduced by
removing a portion of
VOCs and SVOCs from
soils and through reduction
in GETS treatment volume.
Five year reviews, cap
maintenance, and institutional
controls would be required
indefinitely.
GETS operational costs might
be reduced by removing a
portion of VOCs, SVOCs,
pesticides, and PCBs from
soils and through reduction in
GETS treatment volume.
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Table 5.1
Individual Evaluation of Remedial Alternatives
for Standard Chlorine of Delaware Operable Unit 3
Page 4 of 7
4. REDUCTION OF CONTAMINANT MOBILITY, TOXICITY, OR VOLUME
Reduction of toxicity, mobility
or volume
Irreversible treatment
Type and quantity of residuals
remaining after treatment.
Statutory preference for
treatment
None
None
Original
contamination
remains.
Does not satisfy
Mobility of contaminants under capped
area would be controlled;
Toxicity and volume of contamination
under the cap would remain the same with
the exception of minimal soil gas
contaminant reduction.
Minimal soil gas contaminant removal
through gas collection system
Most of the original contamination would
remain under the cap;
Minimal soil gas contaminant removal
through gas collection system
Does not satisfy
Mobility of the
contaminants under the cap
would be controlled as in
Alternative 2A.
Removal of VOCs from
some areas reduces
contamination toxicity and
volume under the cap.
Organic contaminants are
irreversibly removed from
soils and soil gas in "hot
spot" areas.
SVOCs, PCBs/dioxins, and
metals remain in soil under
cap; VOCs from
contaminated groundwater
in soil gas; Carbon from
SVE vapor treatment
requires regeneration or
disposal.
Satisfies
Mobility of the contaminants
under the cap would be
controlled as in Alternative
2A.
Total toxicity and volume of
contamination under cap is
reduced.
Organic contaminants are
irreversibly removed from
soils and soil gas in "hot
spot" areas.
Metals contamination
remains; SVOCs,
PCBs/dioxins, and metals
remain in soil near the soil
bentonite barrier; Carbon
from vapor treatment requires
regeneration or disposal.
Satisfies
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Table 5.1
Individual Evaluation of Remedial Alternatives
for Standard Chlorine of Delaware Operable Unit 3
Page 5 of 7
5. SHORT-TERM EFFECTIVENESS
Community Protection
Worker Protection
Environmental Impacts
Time Until Action is Completed
Continued
impact from
existing
conditions
No significant
risk to workers.
Continued
impact from
existing
conditions.
Not applicable
Temporary increase in contaminated dust
production and VOC escape would be
expected during cap construction; Dust and
vapor suppression measures would be
employed.
PPE required for protection from dust and
vapor during construction.
Wildlife exposure would remain at current
level of contamination during cap
construction;
Stormwater controls, dust and vapor
controls, and contamination pads could be
used to prevent spread of contamination
from the cap construction area;
Approximately 6 months to complete cap
(depending on cap type) .
Dust and vapor controls as
in Alternative 2A;
Incorporating SVE wells
into cap design would result
in longer exposure to
contamination during
construction.
PPE required for protection
from dust and vapor during
construction and SVE
operation.
See Alternative 2A
6-9 months to complete cap
and SVE system
construction;
2-3 years to complete SVE
Dust and vapor controls as in
Alternative 2A; Duration of
potential exposure during
construction and ISTD
treatment would be
approximately two to three
years); Contaminants would
be mobilized into soil vapor
as the soil is heated by ISTD.
Additional controls would be
employed to ensure the
contaminated soil vapor is
captured
PPE required for protection
from dust and vapor during
construction and ISTD
operation.
See Alternative 2A
2 to 3 years to complete
ISTD;
Approximately 6 months to
complete cap following ISTD.
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Table 5.1
Individual Evaluation of Remedial Alternatives
for Standard Chlorine of Delaware Operable Unit 3
Page 6 of 7
6. IMPLEMENTABILITY
Ability to obtain approvals and
coordinate with other agencies
Not applicable
Coordination would be required with
DNREC to determine compliance with
ARARs;
Compliance with the substantive
requirements of the well permitting
program would be required.
Qualified personnel and appropriate
coordination with other agencies would be
required for construction activities.
See Alternative 2A.
Additionally, air permit
equivalence and sampling
would likely be required for
SVE discharge.
Appropriate coordination
with State well permitting
office would be required
for hundreds of SVE wells.
See Alternative 2A.
Additionally, air permit
equivalence and sampling
would likely be required for
ISTD discharge.
Appropriate coordination with
State well permitting office
would be required for
thousands of ISTD wells.
Implementability at the site
Not applicable
Surface cap can be easily constructed at the
site; Care would be needed so as not to
damage IGR features and to tie the surface
cap to the soil bentonite walls; Substantial
demolition of surface and subsurface
structures and debris removal/disposal
would be required; GETS building potable
water line would have to be rerouted
around capped area.
See Alternative 2A.
SVE can be implemented at
the site; Pilot testing
required for SVE; SVE
piping could be installed
under the cap and used as
passive soil vapor capture
system after SVE is
completed.
See Alternative 2A.
ISTD can be implemented at
the site; ISTD would be
completed before cap is
constructed; Pilot testing
required for ISTD
ISTD piping and soil heating
elements would be removed
upon ISTD completion.
Availability of services and
capacities
Not applicable
Required services are readily available
Required services are
readily available
Required services are readily
available; Higher voltage
electrical supply and natural
gas supply would need to be
brought onto site.
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Table 5.1
Individual Evaluation of Remedial Alternatives
for Standard Chlorine of Delaware Operable Unit 3
Page 7 of 7
Criteria
Availability of equipment,
specialists, and materials
Availability of technologies
Alternative 1:
No Action
Not applicable
Not applicable
Alternative 2A : Surface Cap
Standard construction equipment and
materials are required.
Cap technology is readily available and
widely used.
Alternative 2B: Surface
Cap with Soil Vapor
Extraction
Equipment, specialists and
materials needed for cap
construction and SVE
construction and operation
are readily available from
local vendors.
Cap and SVE technologies
are readily available and
widely used.
Alternative 2C: Surface Cap
with In Situ Thermal
Desorption
Equipment, specialists and
materials needed for cap
construction and ISTD
construction and operation are
readily available from local
vendors.
Cap and ISTD technologies
are readily available and have
been used for remediation
sites.
7. COST
Capital Cost
Present Worth of O&M Cost
Alternative Present Worth Cost
$0
$0
$0
$11.1 to $17. 5 Million
$255,000 to $949,000
$11.6to$18.5Million(1)
$17.8 to $24.3 Million
$1,161,000 to $1,855,000
$19.1 to $26.2 Million
(i)
$92.4 to $98.8 Million
$255,000 to $949,000
$92.8 to $99.8 Million(1)
(1) - The lowest O&M cost for a cap would be for the concrete cap, but the lowest capital cost for a cap is for an asphalt cap.
listed O&M Cost do not equal the Alternative Present Worth Cost.
a result, the sum of the lowest listed capital cost and the lowest
-------
FIGURES
-------
HGL— Feasibility Study Report, Standard Chlorine of Delaware Site—
New Castle County, Delaware
Gas vent
Drain layer -
Membrane
Vent layer -
- Top layer
_ Low permeability
geomembrane/soil layer
Waste
Filename: S:\EPA 010'fROJECTS - WORK ASSIGNMENTS\002
Standard Chlorine RIFS\FS Files\FS Report\Figures\
Figure 5-1. doc
Revised: 06/02/08 CW
Project: El 0002. 12.01
Source:
v HGL
Source:
Figure A-ll. USEPA 1998.
"Evaluation of Subsurface
Engineered Barriers at Waste Sites. "
EPA-542-R-98-005. August 1998
Figure 5.1
Typical Multilayer Cap Design
Schematic
Standard Chlorine of Delaware
SCO FS Report
U.S. EPA Region 3
HydioGeoLogic, Inc. 5/15/09
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site—
New Castle County, Delaware
3" Asphalt Binding Layer
9" Concrete Layer
9" Crushed Stone
Base Layer
—I 30 mm Low
-** Permeability Layer
V Sand Vent Layer
6" Asphalt Base Layer
Concrete Surface Cap
Asphalt Surface Cap
Figure 5.2
Typical Asphalt and Concrete Cap Schematic
Standard Chlorine of Delaware
New Castle County, Delaware
SCO FS Report
U.S. EPA Region 3
HydroGeoLogic, Inc. 5/15/09
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County,
Delaware
6.0 COMPARATIVE ANALYSIS OF ALTERNATIVES
In this Section, remedial alternatives are compared to each other based on the evaluation
criteria presented in Section 5.1.
6.1 OVERALL PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
Alternatives 2A, 2B, and 2C would all reduce human health and ecological risks from soil and
soil gas to the levels specified in Section 2 of this FS Report by containing, and preventing
contact with, contamination through the use of a surface cap which would be tied into the soil
bentonite containment barrier that was constructed as part of the IGR. Alternative 2C would
improve on the level of human health protection (specifically the health of future construction
workers or others performing intrusive site work) afforded by the surface cap by removing
almost all organic contamination from vadose zone soils in the "hot spot" areas. Alternative
2B would also provide some measure of added protection, but would only remove VOCs and
some SVOCs from vadose zone "hot spot" soils. Alternative 1A (No Action) would not
provide protection of the environment or human health.
6.2 COMPLIANCE WITH ARARS
Alternative 1A (No Action) would not meet the ARARs that were identified in Section 2.2.
Alternatives 2A, 2B, and 2C would meet all ARARs, with the exception that the requirement
to construct a liner system will be waived. Instead, any cap that is constructed will be tied into
the soil bentonite containment barrier that was installed as part of the IGR. This barrier is
keyed into a low permeability layer that lies between the contaminated soils of the Columbia
Formation and the underlying drinking water aquifer (the Potomac). This method of
construction will isolate any contaminated OU-3 soils left under the cap from surrounding
uncontaminated areas. This alternative will therefore attain a standard of performance that is
equivalent to the standard that would be attained through the construction of a liner system. As
a result, this ARAR will be waived in accordance with 40 CFR § 300.430(f)(l)(ii)(C)(4).
Alternatives 2A, 2B, and 2C can all be designed and implemented to comply with the all of the
remaining identified ARARs. Although none of these alternatives would reduce organic and
inorganic contaminant concentrations throughout OU-3 soil or soil gas to the PRGs established
in Section 2.3, the installation of a surface cap would eliminate the exposure pathways and
thereby manage the potential risks effectively when combined with appropriate ICs.
6.3 LONG-TERM EFFECTIVENESS AND PERMANENCE
Alternative 2A would provide effective containment of all contaminants located in the soil and
soil gas of OU-3. This would substantially reduce the risks related to, and the potential spread
of, site contaminants. To remain effective over the long term, maintenance activities,
including management of vegetation and burrowing animals and repairs of crack and erosional
features, would be required into perpetuity.
Alternatives 2B (SVE plus surface cap) and 2C (ISTD plus surface cap) would improve on the
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effectiveness of Alternative 2A by reducing or eliminating organic contaminants in the vadose
zone of the previously identified "hot spot" areas. Because SVE would only address VOCs
and ISTD would reduce or eliminate all of the organic contaminants in vadose zone soils in
these areas, Alternative 2C would be the most effective over the long term. Confirmation of
the effectiveness of the SVE and ISTD treatment systems would most likely be checked by
collecting and analyzing vapor samples to determine whether the concentrations in the
extracted vapor have leveled off or been reduced to acceptable levels. The identified
concentrations would then be compared to the soil gas PRGs. In the case of the ISTD, which
will most likely be operated prior to the construction of the cap, soil samples could also be
collected and analyzed to determine whether the treatment has reduced contaminant levels
below those of the soil PRGs. As with Alternative 2A, perpetual maintenance will be required
to ensure the continued effectiveness of Alternatives 2B and 2C.
Alternative 1A (No Action) would not reduce the risks from, or the potential migration of, site
contaminants. As a result, Alternative 1A will not be effective over the long term.
6.4 REDUCTION OF TOXICITY, MOBILITY OR VOLUME
Alternatives 2A, 2B, and 2C will all reduce the mobility of the contaminants through the use of
a surface cap to reduce infiltration (eliminating the soil to groundwater pathway), eliminate
contact of contaminated materials with stormwater (eliminating the soil to sediment pathway),
and containing soil gas (eliminating the soil to ambient air pathway). Alternatives 2B and 2C
also include treatment technologies (SVE and ISTD, respectively) that would reduce the
volume and toxicity of OU-3 contaminants. The greatest reduction of contaminant toxicity and
volume is expected from Alternative 2C (combination of the surface cap and ISTD), as it
would remove VOCs, SVOCs, PCBs, and dioxins from vadose zone soils in the "hot spot"
areas. Alternative 2B (surface cap with SVE) would remove VOCs and some SVOCs from the
"hot spot" areas but would not address dioxins, pesticides, and other less volatile
contaminants. Alternative 2A (surface cap alone) would not reduce the toxicity or volume of
the OU-3 contaminants.
Alternative 1A (No Action) would not reduce the toxicity, mobility or volume of OU-3
contaminants.
6.5 SHORT-TERM EFFECTIVENESS
Alternative 1A (no action) would have the highest short-term effectiveness (lowest short-term
risk) because no disturbance of OU-3 soils would occur with this alternative, minimizing the
potential for release of contaminants.
Short-term risks to construction workers, surrounding communities and the environment are
expected to occur from the implementation of Alternatives 2A, 2B, and 2C. These risks
include exposure to dust and vapor during cap construction activities, as well as continued risks
from the current site conditions before the alternatives are fully implemented. Alternatives 2B
and 2C would be somewhat less effective than Alternative 2A in the short term because of the
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Delaware
increased site activities (well construction, trenching, wiring and piping installation) required
to construct the SVE and ISTD systems. Additionally, the SVE and ISTD systems would
increase the mobility of organic contaminants over the short term. Short term risks associated
with Alternatives 2A, 2B, and 2C can be managed by a combination of institutional controls,
PPE, and vapor and dust suppression measures to be employed during construction activities.
Vapor capture and treatment systems would address any increase in the off-gassing of
contaminants under Alternatives 2B and 2C.
6.6 EMPLEMENTABILITY
Alternative 1A requires no action and is therefore the most easily implemented.
Of the remaining alternatives, construction of a surface cap by itself would be most easily
implemented. Although the potable water line to the treatment building would need to be
rerouted so it does not pass under the cap, this could be accomplished using standard
construction equipment, materials, and methods. Care would also have to be taken to avoid
damage to the existing GETS, piezometers, and monitoring wells, but the overall cap
construction could similarly be performed using standard construction equipment and methods.
Additionally, no further delineation (aside from possibly in the Northern Area) or pilot studies
would be needed before construction of a surface cap covering all of OU-3. Activities to
maintain the surface cap would be similar under Alternatives 2A, 2B, and 2C. These activities
would be partially dependent upon the type of cap selected, but they would generally include
vegetation and burrowing animal control, repair of cracks and erosional features, and
monitoring of site conditions.
The proposed treatment technologies (SVE and ISTD) would require additional
characterization sampling to further delineate the "hot spot areas" and the Northern Area, as
well as pilot studies to optimize well placement, blower and pipe sizing, and, in the case of
ISTD, determination of temperatures that will be required to achieve treatment of the OU-3
contaminants. The time required to construct Alternatives 2B and 2C would also be greater
than that needed to complete the surface cap alone. The SVE and ISTD systems would also
require compliance with the substantive provisions of permit requirements to cover the
installation of hundreds to thousands of wells and compliance with substantive air permit
requirements to cover the off-gas discharge, whereas Alternative 2A would only require the
installation of a small number of monitoring wells. Alternative 2A might also require that the
off-gas from the soil gas capture system comply with substantive air discharge permit
requirements. While SVE could be implemented using the utilities already available on site, it
is likely that a higher voltage electrical supply and a natural gas supply will need to be routed
to the site if ISTD is selected as part of the site remedy.
6.7 COST
Alternative 1A requires no action and would therefore incur no costs.
Alternative 2A would be the least expensive of the remaining alternatives, with an expected
U.S. EPA Region 3
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County,
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present value (taken over 30 years at a discount rate of 5%) of between $11.6 and $18.5
million, depending on the type of cap selected. An asphalt cap would be the least expensive to
install ($11.5 million), followed by a concrete cap ($17.5 million) and the multilayer cap
($18.5 million).
Adding an SVE system to the surface cap (Alternative 2B) to address VOC contamination in
"hot spots" would cost (from a 30 year present value perspective) an estimated $7.7 million
more to implement and maintain than using a surface cap by itself (Alternative 2A). It is
expected that, by installing the SVE system first and using trenches to route conveyance piping
below the ground surface upon which the cap would be installed, impacts on the cap
construction costs shown above would be minimized or eliminated.
If an ISTD system is used prior to surface cap construction (Alternative 2C) to remove organic
contamination in "hot spots", it is projected that the 30 year present value of the remedial
action would be in the range of $92.8 million to $99.8 million. As is the case for the other two
containment alternatives, asphalt would be the least expensive capping material choice,
followed by concrete and multilayer soil.
6.8 STATE AND COMMUNITY ACCEPTANCE
As stated earlier, the state and community acceptance criteria will be addressed during and
following the issuance of the proposed plan and the subsequent public comment period.
6.9 PREFERRED ALTERNATIVE
Based on evaluation of the four retained alternatives using the seven evaluation criteria, it
appears that Alternative 2A (Surface Cap) would be the most cost-effective approach for
addressing the risks from the soil and soil gas contamination that is present in OU-3. This
alternative would be consistent with the identified ARARs and would provide protection of
human health and the environment over the long term by eliminating the soil and sediment
exposure pathways and substantially reducing the soil gas exposure pathways. ICs would be
used to restrict land use, prevent the use of site groundwater, require the inclusion of vapor
intrusion protection in future building construction, ensure that remedial measures remain in
good functional condition, require that any construction activities minimize the impact on and
repair any damage to the cap, and keep the public informed of site developments and hazards.
These controls could be implemented through zoning ordinances, access agreements, restrictive
covenants, and public awareness efforts and would be required to increase the level of
protection and ensure that the surface cap continues to be effective over the long term.
Alternatives 2B and 2C would offer some increased protection of human health during future
intrusive activities (e.g., construction, well installation, and cap repair) by reducing
contaminant levels in "hot spot" soils and soil gas, but any increased risk associated with
Alternative 2A could be managed through the use of PPE, vapor and dust suppression, worker
training and other precautions.
The installation of a surface cap will not reduce the toxicity or volume of the OU-3
U.S. EPA Region 3
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County,
Delaware
contaminants, but it would reduce the mobility of the contaminants by reducing/eliminating
precipitation infiltration, preventing stormwater contact with contaminated soils, preventing the
airborne transport of contaminated soil particles, and minimizing the potential off-gassing of
soil gases. While each of the containment alternatives could be readily constructed,
implementation of Alternative 2A would be the easiest of the three and could be accomplished
in the shortest period of time for the lowest overall cost.
Although asphalt would be the least expensive option and would provide protection that should
be (if properly maintained) equal to that offered by the concrete and multilayer soil options, a
choice must be made as to the possible future uses of the capped area and the importance of
site appearance. While the concrete and asphalt caps would be preferable if redevelopment of
the site for some low occupancy business purpose is envisioned, a multilayer soil cap would
likely be more visually appealing and more amenable to conversion of the land to park space or
naturalized open space.
U.S. EPA Region 3
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County,
Delaware
7.0 REFERENCES
Air Force Center for Engineering and the Environment (AFCEE), 1999. "Survey of Air
Force Landfills, Their Characteristics, and Remediation Strategies". Prepared for Air
Force Center for Environmental Excellence by Mitretek Systems. July 1999.
Black & Veatch, 2007. "Final Baseline Risk Assessment Report, Standard Chlorine of
Delaware Site, New Castle County, Delaware". Black & Veatch Special Projects
Corporation. August 2007.
Black & Veatch, 2007a. "Remedial Investigation Report, Standard Chlorine of Delaware Site,
New Castle County, Delaware". Black & Veatch Special Projects Corporation. August
2007.
Black & Veatch, 2005. Final Groundwater Basis of Design/Design Criteria Report, Standard
Chlorine of Delaware Site, New Castle County, Delaware. Black and Veatch Special
Projects Corporation. September 2005.
Black & Veatch, 2003. "Soil/Sediment Design Comparison Study, Standard Chlorine of
Delaware Site, New Castle County, Delaware". Black & Veatch Special Projects
Corporation. June 2003.
Brayton, 2009. E-mail communication regarding USGS Potomac Formation investigation
findings from Michael Brayton, received May 11, 2009.
Conestoga Rovers & Associates (CRA), 2000. "Work Plan for Site Investigation, Step 4 of
Ecological Risk Assessment, Standard Chlorine of Delaware Superfund Site". Conestoga-
Rovers & Associates. March 2000.
Delaware Department of Natural Resources and Environmental Control (DNREC), 2004.
"State of Delaware Surface Water Quality Standards", Delaware Department of Natural
Resources and Environmental Control. July 11, 2004.
U.S. Environmental Protection Agency (EPA), 2008. "Ecological Soil Screening Levels".
http://www.epa.gov/ecotox/ecossl/.
EPA, 2006. "In Situ Treatment Technologies for Contaminated Soil: Engineering Forum Issue
Paper." U.S. Environmental Protection Agency. EPA 542/F-06/013. November 2006.
EPA, 2001. "Remediation Technology Cost Compendium - Year 2000". EPA-542-R-01-009.
U.S. Environmental Protection Agency. September 2001.
U.S. EPA Region 3
Standard Chlorine of Delaware Site Feasibility Study Report 7-1 HydroGeoLogic, Inc. July 2009
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County,
Delaware
EPA, 2001a. "EPA Risk Assessment Guidance for Superfund (RAGS) - Volume I Human
Health Evaluation Manual, Part D, Standardized Planning, Reporting and Review of
Superfund Risk Assessments". U.S. Environmental Protection Agency. December 2001.
EPA 2000. "A Guide to Developing and Documenting Cost Estimates during the Feasibility
Study". EPA 540-R-00-002 / OSWER 9355.0-75. U.S. Environmental Protection Agency.
July 2000.
EPA 1993. "Presumptive Remedies: Site Characterization and Technology Selection for
CERCLA Sites with Volatile Organic Compounds in Soils". USEPA 540-F-93-048. U.S.
Environmental Protection Agency. 1993.
EPA, 1992. "CERCLA/SUPERFUND Orientation Manual." EPA/542/R-92/005. U.S.
Environmental Protection Agency - Office of Solid Waste and Emergency Response
Technology Innovation Office. October 1992.
EPA, 1989. "EPA Risk Assessment Guidance for Superfund (RAGS) - Volume I Human
Health Evaluation Manual, Part A". EPA/540/1-89/002. U.S. Environmental Protection
Agency. December 1989.
EPA 1988, "Guidance for Conducting Remedial Investigations and Feasibility Studies Under
CERCLA." U.S. Environmental Protection Agency. EPA/540/G-89/004, OSWER
Directive 9355.3-01. October 1988.
Federal Remediation Technologies Roundtable (FRTR), 2002. "Remediation Technologies
Screening Matrix and Reference Guide, Version 4.0". Federal Remediation Technology
Roundtable. http: //www. frtr. gov/matrix2/top_page. html.
Interstate Technology & Regulatory Council (ITRC), 2005. "Technical and Regulatory
Guidance for In Situ Chemical Oxidation of Contaminated Soil and Groundwater", 2nd
Edition. Interstate Technology and Regulatory Council. January 2005.
ITRC, 2003. "Technical and Regulatory Guidance for Surfactant/Cosolvent Flushing of
DNAPL Source Zones", DNAPLs-3. Washington, D.C.: Interstate Technology &
Regulatory Council, DNAPLs Team. Available on the Internet at http://www.itrcweb.org.
ITRC, 1997. "Technical and Regulatory Guidance for Soil Washing." Interstate Technology
and Regulatory Council - Metals in Soil Work Team. December 1997.
Hydrogeologic, Inc. (HGL), 2009. "Wetlands Remedial Approach and Pilot Study Summary
Report for The Standard Chlorine of Delaware Site - New Castle, Delaware".
HydroGeoLogic, Inc. February, 2009.
U.S. EPA Region 3
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Site, Operable Unit 3 (OU-3) — New Castle County,
Delaware
HGL, 2008. "Final Sampling and Analysis Plan - Standard Chlorine of Delaware Site, New
Castle, Delaware". Hydrogeologic, Inc. February 2008.
Jordan and Talley, 1976. Guidebook, Columbia Deposits of Delaware: Delaware Geological
Survey Open File Report No. 8, Jordan, R.R., and Talley J.H. 1976.
Oak Ridge National Laboratory (ORNL), 1997. "Preliminary Remediation Goals for
Ecological Endpoints". U.S. Department of Energy - Oak Ridge National Laboratory,
ES/ER/TM-162/R2. August 1997.
P2Pays, 1998. "It's Electric- Battelle and TerraTherm Team Up to Deploy Six-Phase Soil
Heating." http://www.p2pays.org/ref/14/13975.htm. Spring 1998.
Spoljarac, 1967. "Pleistocene Channels of New Castle County, Delaware". Nenad Spoljaric,
Delaware Geological Survey. May 1967.
TerraTherm, 2008. Vendor quote letter from TerraTherm, Inc. received June 3, 2008.
TerraTherm, 2007. "TerraTherm Pretreatment Design Consideration Frequently Asked
Questions", http://www.terratherm.com/technology/faq.htm.
Weston. 1993. "Feasibility Study (FS) Report, Standard Chlorine of Delaware Inc. Site,
Delaware City Delaware". Roy F. Weston, Inc. May 1993.
Weston. 1992. "Remedial Investigation (RI) Report, Standard Chlorine of Delaware Inc.
Site, Delaware City Delaware". Roy F. Weston, Inc. September 1992.
U.S. EPA Region 3
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Appendix A
PRG Detail Tables
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-l. Summary of Receptors and Target Risks Considered in Calculation of PRGs for the On Facility Soil
I. Site-specific Human Health Risk Parameters from BLRA
Benzene
1 ,2-Dichlorobenzene
1 , 3 -Dichlorobenzene
1 ,4-Dichlorobenzene
Total Dichlorobenzene
Chlorobenzene
1,2,3,4-Tetrachlorobenzene
1,2,4,5-Tetrachlorobenzene
Total Tetrachlorobenzene
Pentachlorobenzene
Hexachlorobenzene
1 ,2,3 -Trichlorobenzene
1,2,4-Trichlorobenzene
1 , 3 ,5 -Trichlorobenzene
Total Trichlorobenzene
2,3,7,8-TCDD
na
na
na
1070
na
na
204
258
na
na
16.8
na
na
na
na
0.114
na
na
na
Liver,
Development
na
na
Kidney
Kidney
na
na
Liver
na
na
na
na
na
na
na
na
0.05
na
na
1
2
na
na
0.04
na
na
na
na
na
na
na
na
0.4
na
na
10
13
na
na
0.3
na
na
na
na
na
na
na
na
4.20E-05
na
na
na
na
na
na
5.20E-05
na
na
na
na
0.027
na
na
na
0.02
na
na
0.8
1
na
na
0.02
na
na
na
na
na
na
na
na
6.30E-06
na
na
na
na
na
na
1.10E-05
na
na
na
na
4.20E-03
na
na
na
0.1
na
na
3
4
na
na
0.09
na
na
na
na
na
na
na
na
1.30E-06
na
na
na
na
na
na
1.70E-06
na
na
na
na
8.90E-04
na
na
na
7
na
na
4
4
na
na
7
na
na
na
na
na
NOTES:
EPC - Exposure Point Concentration
HI - Hazard Index
CR - Cancer Risk
HGL
Page 1 of 9
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HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-l. Summary of Receptors and Target Risks Considered in Calculation of PRGs for the On Facility Soil
Benzene
1 ,2-Dichlorobenzene
1 , 3 -Dichlorobenzene
1 ,4-Dichlorobenzene
Total Dichlorobenzene
Chlorobenzene
1,2,3,4-Tetrachlorobenzene
1,2,4,5-Tetrachlorobenzene
Total Tetrachlorobenzene
Pentachlorobenzene
Hexachlorobenzene
1 ,2,3 -Trichlorobenzene
1,2,4-Trichlorobenzene
1 , 3 ,5 -Trichlorobenzene
Total Trichlorobenzene
2,3,7,8-TCDD
carbon tetrachloride
chloroform
Trichloroethylene (PCE)
Tetrachloroethylene (TCE)
2-Methylphenol
4,4'-DDD
4,4'-DDE
4,4'-DDT
Acenaphthene
na
na
na
7643
na
na
64
65
na
na
120
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
1529
na
na
17
16
na
na
27
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
1.11E-05
na
na
na
na
na
na
1.11E-05
na
na
na
na
1.11E-05
na
na
na
na
na
na
na
na
na
na
na
na
1,887
na
na
na
na
na
na
17
na
na
na
na
3.02E-04
na
na
na
na
na
na
na
na
na
na
na
na
9,145
na
na
na
na
na
na
110
na
na
na
na
1.42E-03
na
na
na
na
na
na
na
na
na
na
na
na
188.7125
na
na
na
na
na
na
1.69697
na
na
na
na
3.02E-05
na
na
na
na
na
na
na
na
na
na
na
na
914.52991
na
na
na
na
na
na
10.980392
na
na
na
na
0.0001423
na
na
na
na
na
na
na
na
na
HGL
Page 2 of 9
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-l. Summary of Receptors and Target Risks Considered in Calculation of PRGs for the On Facility Soil
II. Considered Human Health PRGs
Units (mg/kg)
Acenaphthylene
Anthracene
Fluoranthene
Fluorene
Naphthalene
Phenanthrene
Total Low Molecular Weight
PAHs
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Chrysene
Dibenz(a,h)anthracene
Indeno( 1 ,2,3-c,d)pyrene
Pyrene
Total High Molecular Weight
PAHs
Pentachlorophenol
Aluminum
Antimony
Beryllium
Chromium
Cobalt
Copper
Iron
Human Health Non-Cancer PRGs
Non-
Cancer
Child
Resident
PRG
Non-Cancer
Industrial
Worker PRG
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
Non-Cancer
Construc-
tion Worker
PRG
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
Human Health Cancer PRG (10-6 cancer risk)
Individual
Chemical
Cancer
Risks
10-6
Cancer
Risk
Resident!
alPRG
10-6
Cancer
Risk
Indus-
trial
Worker
PRG
10-6 Cancer
Risk
Construc-
tion Worker
PRG
Human Health Cancer PRG (10-4 cancer risk)
Individual
Chemical
Cancer
Risks
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
Residential
PRG, 10-4
Industrial
Worker
PRG,
CR=10-4
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
Cons-
truction
Worker
PRG,
CR=10-4
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
Human Health Cancer PRG (10-5
cancer risk)
Residen-
tial PRG,
10-5
Indus-
trial
Worker
PRG,
CR=10-5
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
Cons-
truction
Worker
PRG,
CR=10-5
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
HGL
Page 3 of 9
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-l. Summary of Receptors and Target Risks Considered in Calculation of PRGs for the On Facility Soil
II. Considered Human Health PRGs
Units (mg/kg)
Lead
Manganese
Mercury
Nickel
Thallium
Vanadium
Zinc
Human Health Non-Cancer PRGs
Non-
Cancer
Child
Resident
PRG
Non-Cancer
Industrial
Worker PRG
na
na
na
na
na
na
na
Non-Cancer
Construc-
tion Worker
PRG
na
na
na
na
na
na
na
Human Health Cancer PRG (10-6 cancer risk)
Individual
Chemical
Cancer
Risks
10-6
Cancer
Risk
Resident!
alPRG
10-6
Cancer
Risk
Indus-
trial
Worker
PRG
10-6 Cancer
Risk
Construc-
tion Worker
PRG
Human Health Cancer PRG (10-4 cancer risk)
Individual
Chemical
Cancer
Risks
na
na
na
na
na
na
na
Residential
PRG, 10-4
Industrial
Worker
PRG,
CR=10-4
na
na
na
na
na
na
na
Cons-
truction
Worker
PRG,
CR=10-4
na
na
na
na
na
na
na
Human Health Cancer PRG (10-5
cancer risk)
Residen-
tial PRG,
10-5
Indus-
trial
Worker
PRG,
CR=10-5
na
na
na
na
na
na
na
Cons-
truction
Worker
PRG,
CR=10-5
na
na
na
na
na
na
na
NOTES:
Metals were not included in human health calculations
For noncarcinogens, the target hazard quotient (THQ) of 1 was divided by the number of chemicals in that medium that affected the same target organ.
Grayed out PRGs are not used in calculation of the most limiting PRG
Per-Chemical Cancer risks for 10-6 cancer risk were calculated by using CR = 10-6 for each individual chemical
Per-Chemical Cancer Risks for 10-4 cumulative cancer risks were calculated by dividing 10-4 by total number of cancer-causing chemicals in this media (9 for on facility soil and soil gas)
HGL
Page 4 of 9
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-l. Summary of Receptors and Target Risks Considered in Calculation of PRGs for the On Facility Soil
Benzene
1 ,2-Dichlorobenzene
1 ,3 -Dichlorobenzene
1 ,4-Dichlorobenzene
Total Dichlorobenzene
Chlorobenzene
1,2,3,4-Tetrachlorobenzene
1 ,2,4,5-Tetrachlorobenzene
Total Tetrachlorobenzene
Pentachlorobenzene
Hexachlorobenzene
1 ,2,3 -Trichlorobenzene
1 ,2,4-Trichlorobenzene
1 ,3 ,5 -Trichlorobenzene
Total Trichlorobenzene
2,3,7,8-TCDD
carbon tetrachloride
chloroform
Trichloroethylene (PCE)
Tetrachloroethylene (TCE)
2-Methylphenol
4,4'-DDD
4,4'-DDE
4,4'-DDT
Acenaphthene
Acenaphthylene
Anthracene
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
20
NA
NA
NA
NA
NA
20
20
40
10
NA
10
20
NA
20
20
NA
20
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
1000
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
7.0E-05
NA
NA
NA
NA
1.4E-05
NA
NA
NA
NA
NA
0.005
NA
0.005
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
1.4E-04
NA
NA
NA
NA
NA
0.046
NA
0.043
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
HGL
Page 5 of 9
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-l. Summary of Receptors and Target Risks Considered in Calculation of PRGs for the On Facility Soil
III. Considered Ecological PRGs
Units (mg/kg)
Fluoranthene
Fluorene
Naphthalene
Phenanthrene
Total Low Molecular Weight
PAHs
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Chrysene
Dibenz(a,h)anthracene
Indeno( 1 ,2,3-c,d)pyrene
Pyrene
Total High Molecular Weight
PAHs
Pentachlorophenol
Aluminum
Antimony
Beryllium
Chromium
Cobalt
Copper
Iron
Lead
Manganese
Mercury
Nickel
Eco-
SSL
for
Plants
NA
NA
5
NA
NA
NA
NA
13
70
NA
120
220
NA
38
Eco-SSLs for
Terrestrial
Invertebrates
29
18
31
NA
78
40
NA
NA
80
NA
1700
450
NA
280
ORNL
Benchmark
Concentration
for Plants
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
3
50
5
10
1
20
100
NA
50
500
0.3
30
ORNL
Benchmark
Concentration
for
Earthworms
NA
30
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
6
NA
NA
NA
0.4
NA
50
NA
500
NA
0.1
200
ORNL
Benchmark
Concentration
for Soil
Microorganisms
and Microbial
Processes
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
400
600
NA
NA
10
1000
100
200
900
100
30
90
Robin
NOAEL
PRG
(mg/kg)
0.192
NA
NA
0.210
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.193
NA
1.6E-04
NA
NA
NA
NA
NA
1179
NA
39.80
NA
NA
NA
Robin
LOAEL
PRG
(mg/kg)
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
1548
NA
408.86
NA
NA
NA
Vole
NOAEL
PRG
(mg/kg)
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
234.8
NA
NA
NA
0.196
NA
Vole
LOAEL
PRG
(mg/kg)
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
303.9
NA
NA
NA
1.96
NA
HGL
Page 6 of 9
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-l. Summary of Receptors and Target Risks Considered in Calculation of PRGs for the On Facility Soil
III. Considered Ecological PRGs
Units (mg/kg)
Thallium
Vanadium
Zinc
Eco-
SSL
for
Plants
NA
NA
160
Eco-SSLs for
Terrestrial
Invertebrates
NA
NA
120
ORNL
Benchmark
Concentration
for Plants
1
2
50
ORNL
Benchmark
Concentration
for
Earthworms
NA
NA
200
ORNL
Benchmark
Concentration
for Soil
Microorganisms
and Microbial
Processes
NA
20
100
Robin
NOAEL
PRG
(mg/kg)
NA
NA
39.96
Robin
LOAEL
PRG
(mg/kg)
NA
NA
360.98
Vole
NOAEL
PRG
(mg/kg)
NA
NA
6667
Vole
LOAEL
PRG
(mg/kg)
NA
NA
13333
HGL
Page 7 of 9
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-l. Summary of Receptors and Target Risks Considered in Calculation of PRGs for the On Facility Soil
Benzene
1 ,2-Dichlorobenzene
1 ,3 -Dichlorobenzene
1 ,4-Dichlorobenzene
Total Dichlorobenzene
Chlorobenzene
1 ,2,3,4-Tetrachlorobenzene
1,2,4,5-Tetrachlorobenzene
Total Tetrachlorobenzene
Pentachlorobenzene
Hexachlorobenzene
1,2,3-Trichlorobenzene
1 ,2,4-Trichlorobenzene
1,3,5 -Trichlorobenzene
Total Trichlorobenzene
2,3,7,8-TCDD
carbon tetrachloride
chloroform
Trichloroethylene (PCE)
Tetrachloroethylene (TCE)
2-Methylphenol
4,4'-DDD
4,4'-DDE
4,4'-DDT
na
na
na
20
20
40
10
16
10
20
7.01E-05
20
20
na
20
1.4E-05
na
na
na
na
na
4.9E-03
na
4.6E-03
na
na
na
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Earthworms
Construction Worker PRG, Non-Cancer (1)
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Earthworms
Robin NOAEL PRG
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Earthworms
na
ORNL Benchmark Concentration for Earthworms
Robin NOAEL PRG
na
na
na
na
na
Robin NOAEL PRG
na
Robin NOAEL PRG
Acenaphthene
Acenaphthylene
Anthracene
Fluoranthene
Fluorene
Naphthalene
Phenanthrene
Total Low Molecular Weight PAHs
20
na
na
0.192
30
na
0.210
29
ORNL Benchmark Concentration for Plants
na
na
Robin NOAEL PRG
ORNL Benchmark Concentration for Earthworms
na
Robin NOAEL PRG
Eco-SSLs for Terrestrial Invertebrates
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Chrysene
na
na
na
na
na
na
na
na
na
na
na
na
v HGL
Page 8 of 9
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-l. Summary of Receptors and Target Risks Considered in Calculation of PRGs for the On Facility Soil
IV. On-Facility Soil Limiting PRGs
(mg/kg)
Chemicals of Potential Concern
Dihen/(a 1i)anthracene
Indeno( 1 ,2,3 -c,d)pyrene
Pyrene
Total High Molecular Weight PAHs
Pentachlorophenol
Lowest PRG,
mg/kg
na
na
1.9E-01
18
1.6E-04
Limiting PRG Receptor
na
na
Robin NOAEL PRG
Eco-SSLs for Terrestrial Invertebrates
Robin NOAEL PRG
Metals
Aluminum
Antimony
Beryllium
Chromium
Cobalt
Copper
Iron
Lead
Manganese
Mercury
Nickel
Thallium
Vanadium
Zinc
50
5
10
0.4
13
50
200
39.801
100
0.1
30
1
2
40.0
ORNL Benchmark Concentration for Plants
ORNL Benchmark Concentration for Plants
ORNL Benchmark Concentration for Plants
ORNL Benchmark Concentration for Earthworms
Eco-SSL for Plants
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Soil Microorganisms and Microbial
Processes
Robin NOAEL PRG
ORNL Benchmark Concentration for Soil Microorganisms and Microbial
Processes
ORNL Benchmark Concentration for Earthworms
ORNL Benchmark Concentration for Plants
ORNL Benchmark Concentration for Plants
ORNL Benchmark Concentration for Plants
Robin NOAEL PRG
NOTES: PRGs for the 10~6 target cancer risk and PRGs for residential receptor were not used in the calculation of limiting PRGs
(1) - The PRG for total tetrachlorobenzenes would supercede the PRG for 1,2,4,5-tetrachlorobenzene because the total number is lower.
v HGL
Page 9 of 9
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-2. Summary of Receptors and Target Risks Considered in Calculation of PRGs for the On-Facility Soil Gas
I. Site-specific Parameters from BLRA
Benzene
1 ,4-Dichlorobenzene
Chlorobenzene
carbon tetrachloride
chloroform
PCE
TCE
1 ,2-Dichlorobenzene
22000
23900
96600
4280
23700
1000
123
10800
Blood, Immune
Liver
Liver ,Kidney
Liver
CNS, Liver, Kidney
CNS
CNS, Liver,
Endocrine
Body weight
7
0.5
30
0.4
8
0.07
0.05
1
20
1
60
1
20
0.2
0.1
3
9.31E-04
1.40E-03
na
6.71E-04
4.91E-03
6.41E-05
1.24E-04
na
3
0.2
10
0.2
3
0.03
0.02
0.5
2.50E-04
3.80E-04
na
1.80E-04
1.30E-03
1.80E-05
3.40E-05
na
0.005
3.00E-04
0.02
3.00E-04
0.006
4.00E-05
3.00E-05
8.00E-04
1.70E-08
2.20E-08
na
1.10E-08
9.90E-08
l.OOE-09
2.10E-09
na
1
7
7
7
7
3
7
1
NOTES:
EPC - Exposure Point Concentration
HI - Hazard Index
CR - Cancer Risk
HGL
Page lof 2
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-2. Summary of Receptors and Target Risks Considered in Calculation of PRGs for the On-Facility Soil Gas
Units (soil gas,
ppb)
Benzene
1,4-
Dichlorobenzene
Chlorobenzene
carbon
tetrachloride
chloroform
PCE
TCE
1,2-
Dichlorobenzene
Human Health PRG, Non-
Cancer
Non-
Cancer
Child
Residen
tPRG
LI 00
3.414
230
611
169
1.667
176
3.600
Non-
Cancer
Indus-
trial
Worker
PRG
7,333
17,071
1,380
3,057
1,129
11,111
879
21,600
Non-
Cancer
Construc-
tion
Worker
PRG
4,400,000
11,380,952
690,000
2,038,095
564,286
8,333,333
585,714
13,500,000
Human Health Cancer PRG (10-6
cancer risk)
10-6
Cancer
Risk
Resident!
alPRG
24
1?
na
6
5
16
1
na
10-6
Cancer
Risk
Indus-
trial
Worker
PRG
88
63
na
24
18
56
4
na
10-6
Cancer
Risk
Construc-
tion
Worker
PRG
L294J18
1.086.364
na
389,091
239,394
1.000.000
58.571
na
Human Health Cancer PRG (10-4 cancer risk)
Individu
al
Chemical
Cancer
Risks
1.11E-05
1.11E-05
na
1.11E-05
1.11E-05
1.11E-05
1.11E-05
na
Resident!
al PRG,
10-4
263
190
71
54
173
11
na
Indus-
trial
Worker
PRG,
CR=10-4
977
698
na
264
202
617
40
na
Construction
Worker
PRG,
CR=10-4
14,379,085
12,070,707
na
4,323,232
2,659,933
11,111,111
650,794
na
Human Health Cancer
cancer risk
Resident!
alPRG,
10-5
26
19
7
5
17
1
na
Industrial
Worker
PRG,
CR=10-5
98
70
na
26
20
62
4
na
PRG (10-5
Construc-
tion
Worker
PRG,
CR=10-5
1,437,908
1,207,071
na
432,323
265,993
1,111,111
65,079
na
Limiting PRG
Lowest
PRG,
ppb
98
70
1,380
26
20
62
4
21,600
Limiting PRG
Receptor
Industrial Worker
PRG, CR=10-5
Industrial Worker
PRG, CR=10-5
Non-Cancer Industrial
Worker PRG
Industrial Worker
PRG, CR=10-5
Industrial Worker
PRG, CR=10-5
Industrial Worker
PRG, CR=10-5
Industrial Worker
PRG, CR=10-5
Non-Cancer Industrial
Worker PRG
NOTES:
Metals were not included in human health calculations
For noncarcinogens, the target hazard quotient (THQ) of 1 was divided by the number of chemicals in that medium that affected the same target organ.
Grayed out receptors and target risks are not used in calculation of the most limiting PRG
Per-Chemical Cancer risks for 10-6 cancer risk were calculated by using CR = 10-6 for each individual chemical
Per-Chemical Cancer Risks for 10-4 cumulative cancer risks were calculated by dividing 10-4 by total number of cancer-causing chemicals in this media (9 for on facility soil and soil gas)
HI3L
Page 2of 2
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-3. Summary of Receptors and Target Risks Considered in Calculation of Off Facility Soil PRGs
I. Site-specific Parameters from BLRA
Units (soil gas, ppb)
1 ,4-Dichlorobenzene
1,2,3,4-
Tetrachlorobenzene
1,2,4,5-
Tetrachlorobenzene
Hexachlorobenzene
2,3,7,8-TCDD
4,4'-DDD
4,4'-DDT
Fluoranthene
Pentachlorophenol *
Phenanthrene
Pyrene
Copper
Lead
Mercury
Zinc
EPC, mg/kg
1410
2750
45.5
na
1.28E-04
na
na
na
na
na
na
na
na
na
na
Target Organ
Liver, Development
Kidney
Kidney
na
na
na
na
na
na
na
na
na
na
na
na
Adult
Resident HI
0.07
20
0.3
na
na
na
na
na
na
na
na
na
na
na
na
Child
Resident
HI
0.6
130
2
na
na
na
na
na
na
na
na
na
na
na
na
Resident
Age-Adj
CR
5.40E-05
na
na
na
3.00E-05
na
na
na
na
na
na
na
na
na
na
Industrial
Worker
HI
0.03
10
0.2
na
na
na
na
na
na
na
na
na
na
na
na
Industrial
Worker
CR
8.30E-06
na
na
na
4.70E-06
na
na
na
na
na
na
na
na
na
na
Construction
Worker HI
0.2
40
0.6
na
na
na
na
na
na
na
na
na
na
na
na
Construction
Worker CR
1.80E-06
na
na
na
l.OOE-06
na
na
na
na
na
na
na
na
na
na
Number
of
chemicals
affecting
target
organ
3
3
3
na
na
na
na
na
na
na
na
na
na
na
na
NOTES:
EPC - Exposure Point Concentration
HI - Hazard Index
CR - Cancer Risk
HGL
Page 1 of4
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-3. Summary of Receptors and Target Risks Considered in Calculation of Off Facility Soil PRGs
II. Human Health PRGs
Units (soil gas, ppb)
1 ,4-Dichlorobenzene
1 ,2,3,4-Tetrachlorobenzene
1,2,4,5-Tetrachlorobenzene
Hexachlorobenzene
2,3,7,8-TCDD
4,4'-DDD
4,4'-DDT
Fluoranthene
Pentachlorophenol*
Phenanthrene
Pyrene
Copper
Lead
Mercury
Zinc
Human Health Non-Cancer PRGs
Non-
Cancer
Child
Resident
PRG
783
7.05
7.58
na
na
na
na
na
na
na
na
na
na
na
na
Non-
Cancer
Industrial
Worker
PRG
15,667
92
76
na
na
na
na
na
na
na
na
na
na
na
na
Non-Cancer
Construction
Worker PRG
2,350
23
25
na
na
na
na
na
na
na
na
na
na
na
na
Human Health Cancer PRG (10-6 cancer risk)
Individual
Chemical
Cancer Risks
l.E-06
l.E-06
l.E-06
na
l.E-06
na
na
na
na
na
na
na
na
na
na
10-6 Cancer
Risk
Residential
PRG
26
na
na
na
4.E-06
na
na
na
na
na
na
na
na
na
na
10-6 Cancer
Risk
Industrial
Worker
PRG
170
na
na
na
3.E-05
na
na
na
na
na
na
na
na
na
na
10-6 Cancer
Risk
Construction
Worker
PRG
783
na
na
na
l.E-04
na
na
na
na
na
na
na
na
na
na
Human Health Cancer PRG (10-4 cancer risk)
Individual
Chemical
Cancer
Risks
3.33E-05
na
na
na
3.33E-05
na
na
na
na
na
na
na
na
na
na
Residential
PRG, 10-4
870
na
na
na
1.42E-04
na
na
na
na
na
na
na
na
na
na
Industrial
Worker
PRG,
CR=10-4
5,663
na
na
na
9.08E-04
na
na
na
na
na
na
na
na
na
na
Construction
Worker
PRG,
CR=10-4
26,111
na
na
na
4.27E-03
na
na
na
na
na
na
na
na
na
na
Human Health Cancer PRG
(10-5 cancer risk)
Residential
PRG, 10-5
87.0
na
na
na
1.42E-05
na
na
na
na
na
na
na
na
na
na
Industrial
Worker
PRG,
CR=10-5
566
na
na
na
9.08E-05
na
na
na
na
na
na
na
na
na
na
Construction
Worker PRG,
CR=10-5
2,611
na
na
na
4.27E-04
na
na
na
na
na
na
na
na
na
na
NOTES:
Metals were not included in human health calculations
For noncarcinogens, the target hazard quotient (THQ) of 1 was divided by the number of chemicals in that medium that affected the same target organ.
Grayed out target risks and receptors are not used in calculation of the most limiting PRG
Per-Chemical Cancer risks for 10-6 cancer risk were calculated by using CR = 10-6 for each individual chemical
Per-Chemical Cancer Risks for 10-4 cumulative cancer risks were calculated by dividing 10-4 by total number of cancer-causing chemicals in this media (3 for off-facility soil and soil gas)
HGL
Page 2 of4
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-3. Summary of Receptors and Target Risks Considered in Calculation of Off Facility Soil PRGs
III. Ecological PRGs
Units (mg/kg)
1 ,4-Dichlorobenzene
1,2,3,4-Tetrachlorobenzene
1, 2,4,5 -Tetrachlorobenzene
Hexachlorobenzene
2,3,7,8-TCDD
4,4'-DDD
4,4'-DDT
Fluoranthene
Pentachlorophenol
Phenanthrene
Pyrene
Copper
Lead
Mercury
Zinc
Robin
NOAEL
PRG
na
na
0.00
0.00
0.00
0.00
0.19
0.00
0.21
0.19
1,179.42
39.80
na
39.96
Robin
LOAEL
PRG
na
na
na
0.00
0.05
0.04
1,548.31
408.86
na
360.98
Vole
NOAEL
PRG
na
na
na
na
na
na
na
na
na
na
na
234.85
na
0.20
6,666.67
Vole
LOAEL
PRG
na
na
na
na
na
na
na
na
na
na
na
303.90
na
1.96
13,333.33
HGL
Page 3 of4
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-3. Summary of Receptors and Target Risks Considered in Calculation of Off Facility Soil PRGs
IV. Limiting PRGs (Off-Facility Soil)
Units (mg/kg)
1 ,4-Dichlorobenzene
1,2,3,4-Tetrachlorobenzene
1,2,4,5-Tetrachlorobenzene
Hexachlorobenzene
2,3,7,8-TCDD
4,4'-DDD
4,4'-DDT
Fluoranthene
Pentachlorophenol*
Phenanthrene
Pyrene
Copper
Lead
Mercury
Zinc
Lowest
PRG, mg/kg
566
23
25
7.01E-05
1.40E-05
4.94E-03
4.62E-03
1.92E-01
1.56E-04
2.10E-01
1.93E-01
235
40
1.96E-01
40
Limiting PRG Receptor
Industrial Worker PRG, CR=10-5
Non-Cancer Construction Worker
PRG
Non-Cancer Construction Worker
PRG
Robin NOAEL PRG
Robin NOAEL PRG
Robin NOAEL PRG
Robin NOAEL PRG
Robin NOAEL PRG
Robin NOAEL PRG
Robin NOAEL PRG
Robin NOAEL PRG
Vole NOAEL PRG
Robin NOAEL PRG
Vole NOAEL PRG
Robin NOAEL PRG
HGL
Page 4 of4
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Super/and Site—New Castle, Delaware
Table A-4. Summary of Receptors and Target Risks Considered in Calculation of Off-Facility Soil Gas PRGs
I. Site-specific Parameters from BLRA
1 ,4-Dichlorobenzene
Chlorobenzene
280
970
Liver
Liver,
Kidney
0.02
0.3
0.04
0.7
5.00E-05
na
0.008
0.1
1.40E-05
na
l.OOE-05
2.00E-04
7.90E-10
na
NOTES:
EPC - Exposure Point Concentration
HI - Hazard Index
CR - Cancer Risk
1 ,4-Dichlorobenzene
Chlorobenzene
3
3
0.33
0.33
1.17E+04
3.23E+03
9.33E+06
1.62E+06
3.33E-05
3.33E-05
666
na
1.18E+07
na
67
na
1.18E+06
na
NOTES:
Metals were not included in human health calculations
For noncarcinogens, the target hazard quotient (THQ) of 1 was divided by the number of chemicals in that medium that affected the same target organ.
Grayed out PRGs are not used in calculation of the most limiting PRG
Per-Chemical Cancer risks for 10-6 cancer risk were calculated by using CR = 10-6 for each individual chemical
Per-Chemical Cancer Risks for 10-4 cumulative cancer risks were calculated by dividing 10-4 by total number of cancer-causing chemicals in this media (3 for off-facility soil and soil gas)
1 ,4-Dichlorobenzene
Chlorobenzene
67
3,233
Industrial Worker PRG, CR=10-5
Non-Cancer Industrial Worker PRG
HGL
Page 1 of 1
-------
Appendix B
SCD NPDES Permit Equivalence Documentation from DNREC
-------
STATE OF DELAWARE
DEPARTMENT OF NATURAL RESOURCES &
ENVIRONMENTAL CONTROL
DIVISION OF WATER RESOURCES
89 KINGS HIGHWAY
DOVER, DELAWARE 199O1
iURFACf WATER DISCHARGES SECTION
TMPHONE: {302)?39-9946
FACSIMILE; (302)739-8369
December 17,2008
Mr. Hilary M. Thornton
Remedial Project Manager
DE/VA/WV Remedial Branch
U.S. EPA Region lit (3HS23)
1650 Arch Street, Philadelphia, PA 19103-2029
Re: Metachem Site
NPDES Equivalence
Dear Mr. Thornton,
You had asked for Delaware's requirements if a NPDES permit were issued for the treated
groundwater and stormwater discharges from the old Metachem site1,
I reviewed the submitted analytical results regarding compliance with Delaware State water
quality and technology-based standards, as well as with federal ELG's. That review is based on
procedures in the "Technical Support Document for Water Quality-based Toxics Control"2. The
table below summarizes the results of that analysis. For each discharge, the table lists
Parameters to be monitored
MQnitoring frequency for those parameters,
Waste Load Allocations (WLA), and
Limit numbers for parameters where limits would be required.
1 Formerly Delaware NPDES permit No. DE0020001. The individual NPDES permit for this site was
voided on May 2,2002.
1 U.S.E.P.A., Office of Water (EN-336), March, 1991, EPA/505/2-90-001, PB9H27415
-------
Mr. Hilary Thornton
December 1.7,2008
Page 2 of3
Parameters To Be Monitored
Treated Groundwater
Copper, Total
Zinc, Total
Lead, Total
Hardness (as CaCO3)
Benzene
Chlorobenzene
Ethylbenzene
1,2-Dichlorobenzene
1,3-Dlchlorobenzene
1,4-Dlchlorobenzene
Hexachlorobenzene
Nitrobenzene
Outfall 002 (Stormwater Runoff)
iron, Total
Copper, Total
Zinc, Total
Lead, Total
Hardness (as CaCO3)
Outfall 001 (Stormwater Runoff)
Iron, Total
Copper, Total
Zinc, Total
Lead, Total
Hardness (as CaCO3)
Waste Load
Allocation (ppb)
. • 15 ' •
128
72
— .
0.033
2,000
16
138
44
—
2,000
7.4
68
32
-
Monitoring
Frequency
Monthly
Monthly
Monthly
Monthly
Quarterly
Quarterly
Quarterly
Quarterly
Quarterly
Quarterly
Quarterly
Quarterly
Annual
Annual
Annual
Annual
Annual
Annual
Annual
Annual
Annual
Annual
Avg, Limit
(ppb)
6.2
50
aid""7"
Maximum
Limit {ppb)
15
130
70
For the treated groundwater discharge, the monitoring for organics should be primarily to
detect break-through for the carbon filters. If that is adequately checked, the parameter-
specific monitoring as specified above can be relatively infrequent, ie., quarterly.
Monitoring methods should be sufficiently sensitive to ensure that the discharge meets the
WLAs: All calculated WLAs are shown in the enclosed CD, labeled "Metachem Delaware, NPDES
Equivalence", containing calculations spreadsheets for each discharge.
There is a PCBTMDL for the receiving waters In the vicinity of the referenced discharges. The
DRBC is helping with initial implementation of that TMDL As Gregory Cavallo of the DRBC has
told you, the discharges from this site have been identified as needing additional high-resolution
Non-detected, but likely present
-------
Mr. Hilary Thornton Page 3 of 3
December 17, 2008
PCB congener monitoring with method 1668A, as modified by the DRBC. Please see
http://www.5tate.nj.us/drbc/PCB info. htm for further details regarding those requirements,
Please contact me at 302-739-9946 or via John.DeFriece@State.DE. US if you have questions or
would like to discuss this further.
Sincerely,
John R. DeFriece, P.E.
Program Manager
Discharge. Permits Program
Enclosure
Cc: R. Peder Hansen
-------
Appendix C
Remedial Technology Cost Estimates
-------
Appendix C-l
Multilayer Soil Surface Cap Cost Estimate
-------
Appendix C-l
Multilayer Surface Cap Cost Estimate
Soil Cover Alternative # 2A
On Facility Cap Area
Northern Area Cap Area
Line Item
Mobilization
Work Plans
Equip. / Contractor Mobilization
Install Runoff Controls(silt fence)
Site Preparation
Demolition of Surface Structures
Concrete Removal
Asphalt Removal
Concrete /Asphalt Crush
Soil Removal
Storage and Replacement
Subsurface Infrastructure Removal
Overhead Utility
Dust Suppression
Materials Salvage / Recycle
Non-Haz Debris Transport/Dispose
Hazardous Debris Disposal
Soil Characterization
Soil Storage / Non-Haz Disposal
Soil Storage / Haz Disposal
Grading
Compaction
Cap Placement
Upper Layer(s)
Top Cover
Burrow Barrier
993,168
110,352
60,984
6,776
Unit
Lump Sum
Lump Sum
Linear Feet
Square Foot
Cubic Yard
Square Yard
Cubic Yard
Cubic Yard
Cubic Yard
Linear Feet
Each
Square Foot
Lump Sum
Cubic Yard
Cubic Yard
Each
Cubic Yard
Cubic Yard
Cubic Yard
Cubic Yard
Cubic Yard
Cubic Yard
sqft
sqyd
sqft
sqyd
Quantity
1
1
3,986
50,000
19,248
39,357
63,000
71,455
71,455
6,290
10
993,168
0
7,700
0
0
0
0
309,950
309,950
23,719
20,929
22.8
1.4
Unit Cost
$ 75,000
$ 40,000
$ 0.79
$ 1.00
$ 14.05
$ 6.70
$ 22.28
$ 1.87
$ 8.04
$ 3.77
$ 3,200
$ 0.01
1,000
$ 57.00
$ 198.00
$ 1,000.00
$ 46.15
$ 152.31
$ 1.40
$ 0.58
$ 22.37
$ 20.00
acres
acres
Cost
$75,000
$40,000
$3,149
$50,000
$270,432
$263,690
$1,403,640
$133,943
$574,501
$23,713
$32,000
$9,932
-
$438,900
$0
$0
$0
$0
$433,931
$179,771
$530,596
$418,572
2008 Cost
$75,000
$40,000
$3,739
$50,000
$321,078
$313,073
$1,403,640
$159,027
$682,092
$25,152
$33,942
$11,792
$0
$521,096
$0
$0
$0
$0
$515,196
$213,438
$629,965
$418,572
Estimated Cost Escalation Factors
2004
2005
2006
Reference
10.0%
6.0%
5.6%
Engineering Judgment
Engineering Judgment
2007
2008
0227007041000 Means (2005)
See tab Demolition Qtys
0205505542000 Means (2005)
0205505541750 Means (2005)
4.5%
1.5%
Factor =
2004 - 08
2005 - 08
2006 - 08
2007 - 08
Vendor Quotes for Unit Price with Crushed Concrete to be spread (
0222002380260 Means (2005)
0222002660040 Means (2005) times two
See tab Utilities
See tab Utilities
33080585 Means (2005) water by truck
No salvageable materials present
RBirdSection4_cost_tables_w_S7[(S3)Excavation_offsite]
Assume same rate as for haz soil and 1 cy = 1.3 tons
RBirdSection4_cost_tables_w_S7[(S3)Excavation_offsite]
RBirdSection4 cost tables w S7[(S3)Excavation offsite]
RBirdSection4_cost_tables_w_S7[(S3)Excavation_offsite]
0222002661600 Means (2005);Dig and Cap Qty for amounts
0222002267200 Means (2005); Dig and Cap Qty for amounts
18050301 Means (2005)
Engineering Judgment
130.6%
118.7%
112.0%
106.1%
Cost Base
2008
2008
2005
2008
2005
2005
2008
2005
2005
2007
2007
2005
2008
2005
2005
2005
2005
2005
2005
2005
2005
2008
Appendix C-l Cap Costs Soil Alt 2A
Cost-Soil Cap 2A
Page 1 of 9
-------
Appendix C-l
Multilayer Surface Cap Cost Estimate
Line Item
Soil Cover
Concrete
Asphalt
Membrane Layer
Drainage Layer
Membrane Layer
Low Permeability Barrier - Clay
Low Permeability Barrier Membrane
Vapor Vent Layer - Soil
Vapor Vent Layer - Engineered
Foundation Layer
Imported Fill
Vent Piping System
Dust Suppression
Grading
Compaction
Extraction Well Modifications
Monitoring Well Modifications
Well Abandonment
Cap Completion
Re-route potable water line
Interconnection with Barrier
Surface Runoff Controls
Establish Vegetation Cover
Access Controls - Fence Modification
Access Controls - Signs
Monitoring Network
Demobilization
Project Support
Engineering Design
Unit
Cubic Yard
Square Yard
Square Yard
Square Yard
Cubic Yard
Square Yard
Cubic Yard
Square Yard
Cubic Yard
Square Feet
Cubic Yard
Cubic Yard
Lump Sum
Square Foot
Acres
Cubic Yard
Each
Each
Each
Linear Feet
Linear Feet
Linear Feet
Square Foot
Linear Feet
Linear Feet
Lump Sum
Lump Sum
12%
Quantity
71,157
0
0
110,352
47,438
110,352
94,876
110,352
47,438
0
0
15,600
1
993,168
22.8
284,629
3
11
0
2,000
3,986
1
993,168
3,941
3941
0
1
of Subtotal
Unit Cost
$ 6.97
$ 10.86
$ 9.60
$ 1.60
$ 10.55
$ 4.31
$ 21.56
$ 4.31
$ 10.55
$ 0.54
$ 6.97
$ 18.00
$ 431,700.00
$ 0.01
$ 5,000.00
$ 0.58
$ 20,000
$ 4,000
$ 700
$ 38.51
$ 7.60
$ 214,000
$ 0.05
$ 2.00
$ 0.20
$ 10,000
$ 10,000
Subtotal
Cost
$495,966
$0
$0
$176,563
$500,473
$475,617
$2,045,535
$475,617
$500,473
$0
$0
$280,795
—
$9,932
$114,000
$165,085
$60,000
$44,000
$0
$77,022
$30,296
$214,000
$48,665
$7,882
$788
$0
$15,000
S 10,619,479
$1,274,337
2008 Cost
$588,849
$0
$0
$209,629
$594,200
$564,689
$2,428,617
$564,689
$594,200
$0
$0
$280,795
$ 431,700.00
$11,792
$135,350
$196,002
$60,000
$44,000
$0
$0
$81,695
$35,970
$226,984
$57,779
$7,882
$788
$0
$15,000
S 12,547,412
$1,274,337
Reference
17030422 Means (2005)
18010314 Means (2005)
0251001040160&0380 Means (2005)
8 oz BoomEnviro (.80); 0.80 labor (2005 Means rate = .74)
17030430 Means (2005)
30 mil BoomEnviro (3.51); 0.80 labor (Means rate = .74)
33080507 Means (2005)
30 mil BoomEnviro (3.51); 0.80 labor (Means rate = .74)
17030430 Means (2005)
33080523 Means (2005)
17030422 Means (2005)
Engineering Judgment
2008 Vendor Quote
33080585 Means (2005) water by truck
RBirdSection4_cost_tables_w_S7[(S3)Excavation_offsite]
0222002267200 Means (2005)
Engineering Judgment
Engineering Judgment
Engineering Judgment
See tab Utilities
10 x Poly Liner Anchor Trench 33080503 Means
See tab Runoff
0293003080400 Means (2005)
Engineering Judgment
1 sign / 500 ft of perimeter; $100 installed = $0.20/ft
Engineering Judgment
Past Project Experience
Cost Base
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2008
2005
2005
2005
2008
2008
2008
2007
2005
2007
2005
2008
2008
2008
2008
2008
Appendix C-l Cap Costs Soil Alt 2A
Cost-Soil Cap 2A
Page 2 of 9
-------
Appendix C-l
Multilayer Surface Cap Cost Estimate
Line Item
Project Management
Construction Management
Waste Management
Contingencies
Completion Reports
Operation and Maintenance
Air Quality Monitoring, 4/y, 2 hr ea
Periodic Inspection (4/yr, engr, 8 hr ea)
Burrowing Animal Control, allowance
Mowing (6x/yr)
Hydroseeding, repair veg cover (10%/yr)
Cap Repairs/Fill/Regrading/Compaction (5
Fence Repairs (10%)
Reporting (1/yr)
Total
Present Value of O&M
Unit
10%
8%
2%
15%
Lump Sum
TOTAL IN
hrs
hrs
each
Acre
Acre
cy
Linear Feet
hrs
Quantity
of Subtotal
of Subtotal
of Subtotal
of Subtotal
STALLED C
8
32
1
136.8
2.42
2616
399
24
Unit Cost
Subtotal
OST
$ 100.00
$ 100.00
$ 2,500.00
$ 28.98
$ 537.62
$ 11.16
$ 15.00
$ 100.00
Northern Area Costing Estimation
Demolition Charges
Demolition Charges with Project Support
Cap Construction Charges w/o Demolition
Per Acre Cap Construction Costs w/o Demolition
Estimated Northern Area Cap Construction Cost
$2,761,468
$4,059,357.28
$13,479,209.67
$591,193.41
$827,670.77
Cost
$1,061,948
$849,558
$212,390
$1,592,922
$4,991,155
$15,610,634
$ 800
$ 3,200
$ 2,500.00
$3,964
$1,301
$29,193
$5,979
$ 2,400
$ 49,338
$ 758,445
2008 Cost
$1,061,948
$849,558
$212,390
$1,592,922
$4,991,155
$17,538,567
$ 800
$ 3,200
$ 2,500
$ 5,178
$ 1,699
$ 38,126
$ 7,809
$ 2,400
-
$ 61,712
$ 948,667
$ 18,487,234
Reference
Past Project Experience
Past Project Experience
Past Project Experience
EPA 540-R-98-045
engg estimate
engg estimate
guesswork
18050415029734000 Means (2004)
180504028102002 Means (2004)
17030429 Means (2004)
17020701 Means + $4/ft material allowance
engg estimate
Cost Base
2008
2008
2008
2008
2008
2008
2004
2004
2004
2004
2008
Appendix C-l Cap Costs Soil Alt 2A
Cost-Soil Cap 2A
Page 3 of 9
-------
Appendix C-l
Multilayer Surface Cap Cost Estimate
Excav
Length
1200
ition Geome
Depth
4
;try (ft)
Width
o
3
Means gave cost for 6" line =
Excavation Geometry (ft)
Length
2000
Excav
Length
5090
Depth
4
ition Geome
Depth
4
Width
o
3
;try (ft)
Width
o
J
Volume
CY
533
$ 36.00
Volume
CY
889
Volume
CY
2,262
Cost
$/CY
$ 5.65
$ 2.83
$ 8.48
$ 4,520
$ 3.77
/LF
Cost
$/CY
$ 5.65
$ 5,022
$ 2.51
$ 38.51
Cost
$/CY
$ 5.65
$ 2.83
$ 8.48
$ 19,172
$ 3.77
Potable Wat
er Line Rem
oval
General excavation from Means for 0.5 CY Excavator
Added cost for buried pipe as a percentage =
Sum
Above sum divided by linear feet
Potable Water
Line RePlac
ement
General excavation from Means for 0.5 CY Excavator
Excavation Cost
Excavation $/LF
Total $/LF
Potable Wat
er Line Rem
oval
General excavation from Means for 0.5 CY Excavator
Added cost for buried pipe as a percentage =
Sum
Above sum divided by linear feet
Overhead
Power / Phoi
ic
50%
50%
Eng Judgment
Eng Judgment
Appendix C-l Cap Costs Soil Alt 2A
Utilities
Page 4 of 9
-------
Appendix C-l
Multilayer Surface Cap Cost Estimate
Means gives installation cost for 25' pole as
Assume removal and replacement of each pole
Assume removal at same rate as installation =
Cost factor to re-install within landfill =
3
$ 800.00
$ 800.00
$ 2,400.00
$ 3,200.00
each
each
10 power poles
Total cost per pole used in estimate
13.7 kva and phone
Appendix C-l Cap Costs Soil Alt 2A
Utilities
Page 5 of 9
-------
Appendix C-l
Multilayer Surface Cap Cost Estimate
Desig
Cover thickness - total (b)
Cover slope (%)
11 Paran
Equivalent radius of area covered
icter
=
=
s
6.5
3.00%
560
ft
ft
Soil
Stone
Quantity Assumptions
Excavation Swell Factor (%) :
Compaction Shrink Factor (%):
Excavation Swell Factor (%) :
Compaction Shrink Factor (%):
25%
25%
15%
15%
Base case - No excavation
Maximum height ( h )
Fill Height (k)
e value to calculate cap vol
f-radius to calculate cap vol
Fill Volume
23.3
16.8
217
777
ft
ft
ft
ft
Cap material volume
Maximum
height ( 1
Fill Height (k)
i)
e value to calculate cap vol
f-radius to
calculate cap vol
Fill Volume
17.8
11.3
322
882
ft
ft
ft
ft
Cap material volume
Perimeter dig depth (d)
Excavation width
Fill Radius
Excavation Volume
Site- wide dig depth (w)
5.5
183
377
1
ft
ft
ft
ft
Site- wide dig volume
Soil Cap Layer
Surface
Burrow Barrier
Protection
Geomembrane
Thick
ft
0.5
0.5
1.5
Cover thickness + (slope * equivalent radius)
Sope * esuivalent radius
Eq radius * cover thickness / fill height
Eq radius + e- value
Fill Volume = 0.333 TI (Fill ht)(Fill radius squared)
.337ih*fradiusA2 - .337ik*radiusA2 - 0.57ib(fradiusA2-radiusA2)
Cover thickn
3ss + (slope *
Sope * esuivalent radius
Sel
equivalent ra
Eq radius * cover thickness / fill height
Eq radius + e- value
ected Seen;
dius)
Fill Volume = 0.333 n (Fill ht)(Fill radius squared)
irio for Co
.337ih*fradiusA2 - .337ik*radiusA2 - 0.57ib(fradiusA2-radiusA2)
perimeter dig depth / slope
Equivalent radius - excavation width
Cap
Volume
(cy)
231,261
sting
Cap
Volume
(cy)
231,261
.337id*eqradiusA2 - .337id*fill radiusA2 - 0.57id(eqradiusA2-fill radiusA2)
7rw*fradiusA2
Material
Topsoil
cobble
Sandy loam
Estimated
Vol (cy)
17,789
17,789
53,368
0
Vol (cy) Corrected
Perimeter
Excavate
Volume
(cy)
Perimeter
Excavate
Volume
(cy)
54,947
For Compaction Shrink
23,719
20,929
71,157
Site-wide
Excavate
Volume
(cy)
Site-wide
Excavate
Volume
(cy)
16,508
Interior
Excavate
Volume
(cy)
0
Adjust
Excavate
Volume
(cy)
66,989
Fill
Volume
(cy)
204,338
Fill
Volume
(cy)
78,689
Fill
Export (-)
Import (+)
(cy)
Fill
Export (-)
Import (+)
(cy)
11,700
Excavtn
to Fill
Ratio
0.00
Excavtn
to Fill
Ratio
0.85
Appendix C-l Cap Costs Soil Alt 2A
Dig and Cap Qty
Page 6 of 9
-------
Appendix C-l
Multilayer Surface Cap Cost Estimate
Drainage
Geomembrane
Infiltration Barrier
Geomembrane
Gas Collection
Maximum
height ( 1
Fill Height (k)
Total =
i)
e value to calculate cap vol
f-radius to calculate cap vol
Fill Volume
1.0
2.0
1.0
6.5
17.8
11.3
322
882
ft
ft
ft
ft
Cap material volume
Perimeter dig depth (d)
Excavation width
Fill Radius
Excavation Volume
Site- wide dig depth (w)
5.5
183
377
1
ft
ft
ft
ft
Site- wide dig volume
Sand and gravel
Soil
Sand
Cover thickn
3ss + (slope *
Sope * esuivalent radius
35,579
0
71,157
0
35,579
231,261
Alter
equivalent ra
Eq radius * cover thickness / fill height
Eq radius + e- value
native Exci
dius)
Fill Volume = 0.333 TI (Fill ht)(Fill radius squared)
47,438
94,876
47,438
308,348
ivation Sc«
.337ih*fradiusA2 - .337ik*radiusA2 - 0.57ib(fradiusA2-radiusA2)
perimeter dig depth / slope
Equivalent radius - excavation width
narios
Cap
Volume
(cy)
231,261
.337id*eqradiusA2 - .337id*fill radiusA2 - 0.57id(eqradiusA2-fill radiusA2)
7rw*fradiusA2
Perimeter
Excavate
Volume
(cy)
54,947
Site-wide
Excavate
Volume
(cy)
16,508
Adjust
Excavate
Volume
(cy)
66,989
Fill
Volume
(cy)
78,689
Fill
Export (-)
Import (+)
(cy)
11,700
Excavtn
to Fill
Ratio
0.85
Appendix C-l Cap Costs Soil Alt 2A
Dig and Cap Qty
Page 7 of 9
-------
Appendix C-l
Multilayer Surface Cap Cost Estimate
Design Rainfall (in/hr)
Target Velocity (ft/sec)
Area
ac
11.4
11.4
C Rainfall
(in/hr)
0.45 1.5
0.95
1.5
1.5
2.5
Target
Q Vel
cfs ft/sec
7.695 2.5
16.245
Estimated linear feet of pipe
Number of manholes
Manhole spaciing (ft)
2.5
Req'd
Area
(sqft)
3.078
6.498
Req'd Req'd
Diameter Diameter
(ft) (in)
2.0 23.8
2.9
34.5
4000
10 at unit price of
400
Cost/LF
53.5
96
$ 500.00 equates to per foot
Cost
214,000 Means
384,000 Means
1.25
manholes at 1 per 400 feet
$500 per manhole =
S1.25/LF
Appendix C-l Cap Costs Soil Alt 2A
Runoff
Page 8 of 9
-------
Appendix C-l
Multilayer Surface Cap Cost Estimate
Total Area
Acres
22.8
SqFt
970,824
Acreage
tated in FS
Screening
Report
1
1
Demolition Quantities
Item
Warehouse
NE Tank Farm
Tank Farm Bldg
WWTP
Maint/Locker Bldg
Main Process Area
Rail Siding
Loading Area Tanks
Eastern Process/Glycol
Western Road
Center Road
Road to WWTP
Remaining Area
Length
250
266
100
200
150
200
400
400
300
800
800
1300
Total
Area
SqFt
647,024
Width
200
200
40
200
40
300
60
80
50
15
15
12
Subtotal
Structure
Footprint
%
10
Totals
Bldg
?
1
0
0
0
0
0
0
0
0
0
0
0
50,000
Demo
Area
SqFt
64,702
Area
SqFt
50,000
53,200
4,000
40,000
6,000
60,000
24,000
32,000
15,000
12,000
12,000
15,600
323,800
388,502
Concrete
Thick(ft)
5
2
0.5
1.5
0.5
1.5
1.5
1.5
% Cover
100
100
100
70
100
60
0
70
70
0
0
0
CY
9,259
3,941
74
1,556
111
2,000
0
1,244
583
0
0
0
18,769
Concrete
Thick(ft)
1
% Cover
20
Cubic Yd
479
19,248
Asphalt
% Cover |Sq Yard
0
0
0
0
0
0
0
0
0
90
90
100
0
0
0
0
0
0
0
0
0
10800
10800
15600
37,200
Asphalt
% Cover
30
Sq Yard
2,157
39,357
Disposal Quantities
Assume all debris is non-hazardous.
Assume all tanks are recycled.
Debris Volume Expansion Factors (Ratio of Disposal Volume to In-Place Volume)
Material
Concrete
Wood
Tile
Based on Pilot
Factor
2.3
4.0
3.5
5.0
1.2
demolition
Average
Project Roc
iy Mountai
Light Wood (Offices, etc)
Significant Structure Support
Estimated Cubic Yards based on Square Footage:
Type
Warehouse
NE Tank Farm
Tank Farm Bldg
WWTP
Maint/Locker Bldg
Main Process Area
Rail Siding
Loading Area Tanks
Eastern Process/Glycol
Western Road
Center Road
Road to WWTP
Concrete
Asphalt
Ratio:
cy/sqft
0.10
0.02
0.05
0.10
0.05
0.05
0.01
0.05
0.05
0.05
0.05
0.05
Assume thick (ft)=
0.5
n Arsenal
Disposal
Qty (cy)
5,000
0
0
0
0
0
0
0
0
0
0
0
19,248
6,559
Reductio
0
40
40
50
40
Expand
Factor
2.4
2.0
2.1
2.1
2.1
2.1
2.5
2.1
2.1
2.1
2.1
2.1
Bldg
2.3
2 2
i (%) < Transport
Sub- total
Total =
Landfill
Qty (cy)
12,000
0
0
0
0
0
0
0
0
0
0
0
12,000
44,270
14,431
70,701
Net Factor
2.3
2.4
2.1
2.5
0.72
Appendix C-l Cap Costs Soil Alt 2A
Demolition Qtys
Page 9 of 9
-------
Appendix C-2
Concrete Surface Cap Cost Estimate
-------
Appendix C-2
Concrete Surface Cap Cost Estimate
Concrete Cap Alternative # 2A
Area to be covered
Line Item
Mobilization
Work Plans
Equip. / Contractor Mobilization
Install Runoff Controls(silt fence)
Site Preparation
Demolition of Surface Structures
Concrete Removal
Asphalt Removal
Concrete / Asphalt Crush
Soil Removal
Storage and Replacement
Subsurface Infrastructure Removal
Overhead Utility
Dust Suppression
Materials Salvage / Recycle
Non-Haz Debris Transport/Dispose
Hazardous Debris Disposal
Soil Characterization
Soil Storage / Non-Haz Disposal
Soil Storage / Haz Disposal
Grading
Compaction
Cap Placement
Upper Layer(s)
Top Cover
Burrow Barrier
Soil Cover
993,168
110,352
Unit
Lump Sum
Lump Sum
Linear Feet
Square Foot
Cubic Yard
Square Yard
Cubic Yard
Cubic Yard
Cubic Yard
Linear Feet
Each
Square Foot
Lump Sum
Cubic Yard
Cubic Yard
Each
Tons
Tons
Cubic Yard
Cubic Yard
Cubic Yard
Cubic Yard
Cubic Yard
sqft
sqyd
Quantity
1
1
3,986
50,000
19,248
39,357
63,000
25,784
25,784
6,290
10
993,168
0
7,700
0
0
0
0
100,978
91,405
0
0
0
22.8
Unit Cost
$ 50,000
$ 80,000
$ 0.79
$ 1.00
$ 14.05
$ 6.70
$ 22.28
$ 1.87
$ 8.04
$ 3.77
$ 3,200
$ 0.01
1,000
$ 57.00
$ 257.40
$ 1,000.00
$ 60.00
$ 198.00
$ 1.40
$ 0.58
$ 22.37
$ 20.00
$ 6.97
acres
Cost
$50,000
$80,000
$3,149
$50,000
$270,432
$263,690
$1,403,640
$48,333
$207,306
$23,713
$32,000
$9,932
-
$438,900
$0
$0
$0
$0
$141,369
$53,015
$0
$0
$0
2008 Costs
$50,000
$80,000
$3,739
$50,000
$321,078
$313,073
$1,403,640
$57,385
$246,130
$25,152
$33,942
$11,792
$0
$521,096
$0
$0
$0
$0
$167,844
$62,943
$0
$0
$0
Estimated Cost Escalation Factors
2004
2005
2006
Reference
10.0%
6.0%
5.6%
Engineering Judgment
Engineering Judgment
2007
2008
0227007041000 Means (2005)
See tab Demolition Qtys
0205505542000 Means (2005)
0205505541750 Means (2005)
4.5%
1.5%
Factor =
2004 - 08
2005 - 08
2006 - 08
2007 - 08
Vendor Quotes for Unit Price with Crushed Concrete to be sprea
0222002380260 Means (2005)
0222002660040 Means (2005) times two
See tab Utilities
See tab Utilities
33080585 Means (2005) water by truck
No salvageable materials present
RBirdSection4 cost tables w S7[(S3)Excavation offsite]
Assume same rate as for haz soil and 1 cy = 1.3 tons
RBirdSection4 cost tables w S7[(S3)Excavation offsite]
RBirdSection4_cost_tables_w_S7[(S3)Excavation_offsite]
RBirdSection4 cost tables w S7[(S3)Excavation offsite]
0222002661600 Means (2005); see Dig and Cap Qty tab for amc
0222002267200 Means (2005); see Dig and Cap Qty tab for amc
18050301 Means (2005)
Engineering Judgment
17030422 Means (2005)
130.6%
118.7%
112.0%
106.1%
Cost Base
2008
2008
2005
2008
2005
2005
2008
2005
2005
2007
2007
2005
2008
2005
2005
2005
2005
2005
2005
2005
2005
2008
2005
Appendix C-2 Cap Costs Concrete Alt 2A
Cost-Cement Cap 2A
lof 9
-------
Appendix C-2
Concrete Surface Cap Cost Estimate
Line Item
Concrete
Asphalt
Membrane Layer
Drainage Layer / Base Course
Membrane Layer
Low Permeability Barrier - Clay
Low Permeability Barrier Membrane
Vapor Vent Layer - Soil
Vapor Vent Layer - Engineered
Foundation Layer
Vent Piping System
Dust Suppression
Grading
Compaction
Extraction Well Modifications
Monitoring Well Modifications
Well Abandonment
Cap Completion
Re-route potable water line
Interconnection with Barrier
Surface Runoff Controls
Establish Vegetation Cover
Access Controls - Fence Modification
Access Controls - Signs
Monitoring Network
Demobilization
Project Support
Engineering Design
Project Management
Construction Management
Unit
Square Yard
Square Yard
Square Yard
Square Yard
Square Yard
Cubic Yard
Square Yard
Cubic Yard
Square Feet
Cubic Yard
Lump Sum
Square Foot
Acres
Cubic Yard
Each
Each
Each
Linear Feet
Linear Feet
Linear Feet
Square Foot
Linear Feet
Linear Feet
Lump Sum
Lump Sum
12%
10%
8%
Quantity
110,352
0
0
110,352
0
0
110,352
42,517
0
0
1
993,168
0.0
152,869
3
11
0
2,000
3,986
1
0
3,941
3,941
0
1
of Subtotal
of Subtotal
of Subtotal
Unit Cost
$ 37.63
$ 9.60
$ 1.60
$ 11.90
$ 4.31
$ 21.56
$ 4.31
$ 10.55
$ 0.54
$ 6.97
$ 431,700.00
$ 0.01
$ 5,000.00
$ 0.58
$ 20,000
$ 4,000
$ 700
$ 38.51
$ 7.60
$ 389,000
$ 0.05
$ 2.00
$ 0.20
$ 10,000
$ 15,000
Subtotal
Cost
$4,152,075
$0
$0
$1,313,094
$0
$0
$475,617
$448,559
$0
$0
—
$9,932
$0
$88,664
$60,000
$44,000
$0
$77,022
$30,296
$389,000
$0
$7,882
$788
$0
$15,000
S 10,187,408
$1,222,489
$1,018,741
$814,993
2008 Costs
$4,929,664
$0
$0
$1,559,007
$0
$0
$564,689
$532,564
$0
$0
$ 431,700.00
$11,792
$0
$105,269
$60,000
$44,000
$0
$81,695
$35,970
$412,603
$0
$7,882
$788
$0
$15,000
S 12,140,435
$1,222,489
$1,018,741
$814,993
Reference
02750 300 0200 Means (2005) 230 mm (~9 inch) concrete
0251001040160&0380 Means (2005)
8 oz BoomEnviro (.80); 0.80 labor (Means = .74)
Adjusted 02720 200 0200 Means (2005) 200 mm (~9 inch) 40mi
30 mil BoomEnviro (3.51); 0.80 labor (Means rate = .74)
33080507 Means (2005)
30 mil BoomEnviro (3.51); 0.80 labor (Means rate = .74)
17030430 Means (2005)
33080523 Means (2005)
17030422 Means (2005)
2008 Vendor Quote
33080585 Means (2005) water by truck
RBirdSection4_cost_tables_w_S7[(S3)Excavation_offsite]
0222002267200 Means (2005)
Engineering
Engineering
Engineering
Judgment
Judgment
Judgment
See tab Utilities
10 x Poly Liner Anchor Trench 33080503 Means
See tab Runoff
0293003080400 Means (2005)
Engineering
Judgment
1 sign / 500 ft of perimeter; $100 installed = $0.20/ft
Engineering
Judgment
Past Project Experience
Past Project Experience
Past Project Experience
Cost Base
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2008
2008
2008
2007
2005
2007
2005
2008
2008
2008
2008
2008
2008
2008
Appendix C-2 Cap Costs Concrete Alt 2A
Cost-Cement Cap 2A
2 of 9
-------
Appendix C-2
Concrete Surface Cap Cost Estimate
Line Item
Waste Management
Contingencies
Completion Reports
Operation and Maintenance
Air Quality Monitoring, 4/y, 2 hr ea
Periodic Inspection (4/yr, engr, 8 hr ea)
Burrowing Animal Control
Mowing / Vegetation Support
Cap Repairs (concrete repair, 2%/yr)
Fence Repairs (10%)
Reporting (1/yr)
Total
Present Value of O&M
Unit
2%
15%
Lump Sum
TOTAL INST
hrs
hrs
Acre
Acre
cy
Linear Feet
hrs
Quantity
of Subtotal
of Subtotal
ALLED C(
8
32
728
399
24
Unit Cost
Subtotal
)ST
$ 100.00
$ 100.00
$ 2.30
$ 15.00
$ 100.00
Northern Area Costing Estimation
Demolition Charges
Demolition Charges with Project Support
Cap Construction Charges w/o Demolition
Per Acre Cap Construction Costs w/o Demolition
Estimated Northern Area Cap Construction Cost
$2,761,468
$4,059,357
$13,162,114
$577,286
$808,200
Cost
$203,748
$1,528,111
$4,788,082
$14,975,490
$ 800
$ 3,200
$1,675
$5,979
$ 2,400
$ 14,055
$216,054
2008 Costs
$203,748
$1,821,065
$5,081,036
$17,221,471
$ 800
$ 3,200
$ 1,675
$ 7,809
$ 3,134
$ 16,619
$255,471
Reference
Past Project Experience
EPA 540-R-98-045
engg estimate
engg estimate
Emmons, Sordyl paper, 2006
17020701 Means (2004) + $4/ft material allowance
engg estimate
Cost Base
2008
2008
2008
2008
2004
2008
Appendix C-2 Cap Costs Concrete Alt 2A
Cost-Cement Cap 2A
3 of 9
-------
Appendix C-2
Concrete Surface Cap Cost Estimate
Excav;
Length
1200
ition Geonw
Depth
4
rtry (ft)
Width
3
Means gave cost for 6" line =
Excavation Geometry (ft)
Length
2000
Excav;
Length
5090
Depth
4
ition Geonw
Depth
4
Width
3
rtry (ft)
Width
3
Volume
CY
533
$ 36.00
Volume
CY
889
Volume
CY
2,262
Cost
$/CY
$ 5.65
$ 2.83
$ 8.48
$ 4,520
$ 3.77
/LF
Cost
$/CY
$ 5.65
$ 5,022
$ 2.51
$ 38.51
Cost
$/CY
$ 5.65
$ 2.83
$ 8.48
$ 19,172
$ 3.77
Potable V
fater Line R
emoval
General excavation from Means for 0.5 CY Excavator
Added cost for buried pipe as a percentage =
Sum
Above sum divided by linear feet
Potable Wa
ter Line ReP
lacement
General excavation from Means for 0.5 CY Excavator
Excavation Cost
Excavation $/LF
Total $/LF
Abandoned
Utility Line
Removal
General excavation from Means for 0.5 CY Excavator
Added cost for buried pipe as a percentage =
Sum
Above sum divided by linear feet
Overhe
ad Power / P
hone
50%
50%
Eng Judgment
Eng Judgment
Appendix C-2 Cap Costs Concrete Alt 2A
Utilities
Page 4 of 9
-------
Appendix C-2
Concrete Surface Cap Cost Estimate
Means gives installation cost for 25' pole as
Assume removal and replacement of each pole
Assume removal at same rate as installation =
Cost factor to re-install within landfill =
3
$ 800.00
$ 800.00
$ 2,400.00
$ 3,200.00
each
each
10 power poles
Total cost per pole used in estimate
13.7 kva and phone
Appendix C-2 Cap Costs Concrete Alt 2A
Utilities
Page 5 of 9
-------
Appendix C-2
Concrete Surface Cap Cost Estimate
Desij
Cover thickness - total (b)
Cover slope (%)
*n Paran
Equivalent radius of area covered
icter
=
=
s
2.4
0.50%
560
ft
ft
Soil
Stone
Quantity Assumptions
Excavation Swell Factor (%) :
Compaction Shrink Factor (%):
Excavation Swell Factor (%) :
Compaction Shrink Factor (%):
25%
25%
15%
15%
Base case - No excavation
Maximum height ( h )
Fill Height (k)
e value to calculate cap vol
f-radius to calculate cap vol
Fill Volume
5.2
2.8
480
1040
ft
ft
ft
ft
Cap material volume
Maximui
n height (
Fill Height (k)
h)
e value to calculate cap vol
f-radius to calculate cap vol
Fill Volume
4.2
1.8
747
1307
ft
ft
ft
ft
Cap material volume
Perimeter dig depth (d)
Excavation width
Fill Radius
1
200
360
ft
ft
ft
Excavation Volume
Site-wide dig depth (w)
1
ft
Site-wide dig volume
Soil Cap Layer
Surface
Burrow
Barrier
Base Course
Geomembrane
Drainage
Thick
ft
0.75
0.0
0.66
0.0
X
Cover thickness + (slope * equivalent radius)
Sope * esuivalent radius
Eq radius * cover thickness / fill height
Eq radius + e- value
Fill Volume = 0.333 it (Fill ht)(Fill radius squared)
.337ih*fradiusA2 - .337ik*radiusA2 - 0.57ib(fradiusA2-radiusA2)
Cover thickn
3ss + (slope *
Sope * esuivalent radius
Se
equivalent ra
Eq radius * cover thickness / fill height
Eq radius + e- value
lected Seen
dius)
Fill Volume = 0.333 n (Fill ht)(Fill radius squared)
ario for Co
.337ih*fradiusA2 - .337ik*radiusA2 - 0.57ib(fradiusA2-radiusA2)
perimeter dig depth / slope
Equivalent radius - excavation width
Cap
Volume
(cy)
76,850
sting
Cap
Volume
(cy)
76,850
.337id*eqradiusA2 - .337id*fill radiusA2 - 0.57id(eqradiusA2-fill radiusA2)
7rw*fradiusA2
Material
Concrete
cobble
(~9 inch) 40mm stone
Sand and gravel
Estimated
Vol (cy)
23,916
0
21,046
0
0
Vol (cy) Corrected
For Compa
23,916
0
24,760
0
ction Shrink
Perimeter
Excavate
Volume
(cy)
Perimeter
Excavate
Volume
(cy)
10,705
Note - com
Site-wide
Excavate
Volume
(cy)
Site-wide
Excavate
Volume
(cy)
15,080
:rete costec
Interior
Excavate
Volume
(cy)
0
Adjust
Excavate
Volume
(cy)
24,173
1 in sq yd b
Fill
Volume
(cy)
34,056
Fill
Volume
(cy)
24,127
ased on site
Fill
Export (-)
Import (+)
(cy)
Fill
Export (-)
Import (+)
(cy)
(45)
area
Excavtn
to Fill
Ratio
0.00
Excavtn
to Fill
Ratio
1.00
Appendix C-2 Cap Costs Concrete Alt 2A
Dig and Cap Qty
Page 6 of 9
-------
Appendix C-2
Concrete Surface Cap Cost Estimate
Geomembrane
Infiltration Barrier
Geomembrane
Gas Collection
Maximur
n height (
Fill Height (k)
Total -
h)
e value to calculate cap vol
f-radius to calculate cap vol
Fill Volume
0.0
1.0
2.4
3.95
1.55
867
1427
-
-
-
X
ft
ft
ft
ft
Cap material volume
Perimeter dig depth (d)
Excavation width
Fill Radius
1.25
250
310
ft
ft
ft
Excavation Volume
Site-wide dig depth (w)
0
ft
Site-wide dig volume
Soil
Sand and gravel
absent
included
Cover thickn
3ss + (slope *
Sope * esuivalent radius
0
0
0
31,888
76,850
Alte
equivalent ra
Eq radius * cover thickness / fill height
Eq radius + e- value
rnative Exc
dius)
Fill Volume = 0.333 n (Fill ht)(Fill radius squared)
0
42,517
76,850
avation Sc<
.337ih*fradiusA2 - .337ik*radiusA2 - 0.57ib(fradiusA2-radiusA2)
perimeter dig depth / slope
Equivalent radius - excavation width
marios
Cap
Volume
(cy)
76,850
.337id*eqradiusA2 - .337id*fill radiusA2 - 0.57id(eqradiusA2-fill radiusA2)
7rw*fradiusA2
Perimeter
Excavate
Volume
(cy)
15,817
Site-wide
Excavate
Volume
(cy)
0
Adjust
Excavate
Volume
(cy)
14,828
Fill
Volume
(cy)
5,777
Fill
Export (-)
Import (+)
(cy)
(9,051)
Excavtn
to Fill
Ratio
2.57
Appendix C-2 Cap Costs Concrete Alt 2A
Dig and Cap Qty
Page 7 of 9
-------
Appendix C-2
Concrete Surface Cap Cost Estimate
Design Rainfall (in/hr)
Target Velocity (ft/sec)
1.5
2.5
Area
ac
11.4
11.4
C
0.45
0.95
Rainfall
(in/hr)
1.5
1.5
Q
cfs
7.695
16.245
Vel
ft/sei
2.5
2.5
Target Req'd Req'd Req'd Cost/LF Total /LF
Area Diameter Diameter Pipe w/mhole
(sqft) (ft) (in)
3.078 2.0 23.8
Estimated linear feet of pipe
Number of manholes
Manhole spaciing (ft)
Cost
6.498 2.9
4000
10 at unit price of
400
34.5
53.5 $ 54.75 $219,000 Means
96 $ 97.25 $389,000 Means
Manhole Costs
$ 500.00 equates to per foot $ 1.25
Appendix C-2 Cap Costs Concrete Alt 2A
Runoff
Page 8 of 9
-------
Appendix C-2
Concrete Surface Cap Cost Estimate
On Facility Area
Acreage stated in FS Screening Report
Demolition Quantities
Item
Warehouse
NE Tank Farm
TankFarmBldg
WWTP
Maint/Locker Bldg
Main Process Area
Rail Siding
Loading Area Tanks
Eastern Process/ Glyco]
Western Road
Center Road
Road to WWTP
Remaining Area
Length
250
266
100
200
150
200
400
400
300
800
800
1300
Total
Area
SqFt
647,024
Width
200
200
40
200
40
300
60
80
50
15
15
12
Subtotal
Structure
Footprint
%
10
Totals
Bldg
?
1
0
0
0
0
0
0
0
0
0
0
0
50,000
Demo
Area
SqFt
64,702
Area
SqFt
50,000
53,200
4,000
40,000
6,000
60,000
24,000
32,000
15,000
12,000
12,000
15,600
323,800
388,502
Concrete
Thick(ft) % Cover
5 100
2 100
0.5 100
1.5 70
0.5 100
1.5 60
0
1.5 70
1.5 70
0
0
0
Concrete
Thick(ft) % Cover
1 20
CY %
9,259
3,941
74
1,556
111
2,000
0
1,244
583
0
0
0
18,769
Cubic Yd %
479
19,248
Asphalt
Cover SqYard
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
90 10800
90 10800
100 15600
37,200
Asphalt
Cover SqYard
30 2,157
39,357
Disposal Quantities
Assume all demolition debris is non-hazardous.
Assume all process columns are removed and recycled by IPP.
Debris Volume Expansion Factors (Ratio of Disposal Volume to In-Place Volume)
Based on Pilot Demolition Proj ect Rocky Mountain Arsenal
Material Factor
Concrete
Wood
2.3
4.0 Average
3.5 Light Wood (Offices, etc)
5.0 Significant Structure Support
1.2
Reduction (%) < Transport
0
40
40
50
40
Net Factor
2.3
2.4
2.1
2.5
0.72
Estimated Cubic Yards based on Square Footage:
Type
Warehouse
NE Tank Farm
TankFarmBldg
WWTP
Maint/Locker Bldg
Main Process Area
Rail Siding
Loading Area Tanks
Eastern Process/Glycol
Western Road
Center Road
Road to WWTP
Concrete
Asphalt Assume thick (ft)=
Disposal Expand
Qty (cy) Factor
19,248
6,559
Bldg Sub-total
Landfill
Qty(cy)
12,000
0
0
0
0
0
0
0
0
0
0
0_
12,000
44,270
14.431
70,701
Appendix C-2 Cap Costs Concrete Alt 2A
Demolition Qtys
Page 9 of 9
-------
Appendix C-3
Asphalt Surface Cap Cost Estimate
-------
Appendix C-3
Asphalt Surface Cap Cost Estimate
Asphalt Cap Alternative # 2A
Area to be covered
Line Item
Mobilization
Work Plans
Equip. / Contractor Mobilization
Install Runoff Controls(silt fence)
Site Preparation
Demolition of Surface Structures
Concrete Removal
Asphalt Removal
Concrete / Asphalt Crush
Soil Removal
Storage and Replacement
Subsurface Infrastructure Removal
Overhead Utility
Dust Suppression
Materials Salvage / Recycle
Non-Haz Debris Transport/Dispose
Hazardous Debris Disposal
Soil Characterization
Soil Storage / Non-Haz Disposal
Soil Storage / Haz Disposal
Grading
Compaction
Cap Placement
Upper Layer(s)
Top Cover
Burrow Barrier
Soil Cover
Concrete
Asphalt (Binder + Wearing)
993,168
110,352
Unit
Lump Sum
Lump Sum
Linear Feet
Square Foot
Cubic Yard
Square Yard
Cubic Yard
Cubic Yard
Cubic Yard
Linear Feet
Each
Square Foot
Lump Sum
Cubic Yard
Cubic Yard
Each
Tons
Tons
Cubic Yard
Cubic Yard
Cubic Yard
Cubic Yard
Cubic Yard
Square Yard
Square Yard
sqft
sqyd
Quantity
1
1
3,986
50,000
19,248
39,357
63,000
25,784
25,784
6,290
10
993,168
0
7,700
0
0
0
0
82,521
89,571
0
0
0
0
110,352
22.8
Unit Cost
$ 50,000
$ 80,000
$ 0.79
$ 1.00
$ 14.05
$ 6.70
$ 22.28
$ 1.87
$ 8.04
$ 3.77
$ 3,200
$ 0.01
1,000
$ 57.00
$ 257.40
$ 1,000.00
$ 60.00
$ 198.00
$ 1.40
$ 0.58
$ 22.37
$ 20.00
$ 6.97
$ 37.63
$ 6.36
acres
Cost
$50,000
$80,000
$3,149
$50,000
$270,432
$263,690
$1,403,640
$48,333
$207,306
$23,713
$32,000
$9,932
-
$438,900
$0
$0
$0
$0
$115,530
$51,951
$0
$0
$0
$0
$702,162
2008 Cost
$50,000
$80,000
$3,739
$50,000
$321,078
$313,073
$1,403,640
$57,385
$246,130
$25,152
$33,942
$11,792
$0
$521,096
$0
$0
$0
$0
$137,166
$61,680
$0
$0
$0
$0
$833,661
Estimated Cost Escalation Factors
2004
2005
2006
Reference
10.0%
6.0%
5.6%
Engineering Judgment
Engineering Judgment
2007
2008
0227007041000 Means (2005)
See tab Demolition Qtys
0205505542000 Means (2005)
0205505541750 Means (2005)
4.5%
1.5%
Factor =
2004 - 08
2005 - 08
2006 - 08
2007 - 08
Vendor Quotes for Unit Price with Crushed Concrete to be spread onsite
0222002380260 Means (2005)
0222002660040 Means (2005) times two
See tab Utilities
See tab Utilities
33080585 Means (2005) water by truck
No salvageable materials present
RBirdSection4 cost tables w S7[(S3)Excavation offsite]
Assume same rate as for haz soil and 1 cy = 1.3 tons
RBirdSection4 cost tables w S7[(S3)Excavation offsite]
RBirdSection4 cost tables w S7[(S3)Excavation offsite]
RBirdSection4 cost tables w S7[(S3)Excavation offsite]
0222002661600 Means (2005);Dig and Cap Qty for amnts
0222002267200 Means (2005);Dig and Cap Qty tab amnts
18050301 Means (2005)
Engineering Judgment
17030422 Means (2005)
02750 300 0200 Means (2005) 230 mm (~9 inch) concrete
027403100080 + 027403100300 Means (2005)
130.6%
118.7%
112.0%
106.1%
Cost Base
2008
2008
2005
2008
2005
2005
2008
2005
2005
2007
2007
2005
2008
2005
2005
2005
2005
2005
2005
2005
2005
2008
2005
2005
2005
Appendix C-3 Cap Costs Asphalt Alt 2A
Cost-Asphalt Cap 2A
Page 1 of 10
-------
Appendix C-3
Asphalt Surface Cap Cost Estimate
Line Item
Membrane Layer
Drainage Layer / Base Course
Membrane Layer
Low Permeability Barrier - Clay
Low Permeability Barrier Membrane
Vapor Vent Layer - Soil
Vapor Vent Layer - Engineered
Foundation Layer
Vent Piping System
Dust Suppression
Grading
Compaction
Extraction Well Modifications
Monitoring Well Modifications
Well Abandonment
Cap Completion
Re-route potable water line
Interconnection with Barrier
Surface Runoff Controls
Establish Vegetation Cover
Access Controls - Fence Modification
Access Controls - Signs
Monitoring Network
Demobilization
Project Support
Engineering Design
Project Management
Construction Management
Waste Management
Contingencies
Completion Reports
Unit
Square Yard
Square Yard
Square Yard
Cubic Yard
Square Yard
Cubic Yard
Square Feet
Cubic Yard
Lump Sum
Square Foot
Acres
Cubic Yard
Each
Each
Each
Linear Feet
Linear Feet
Linear Feet
Square Foot
Linear Feet
Linear Feet
Lump Sum
Lump Sum
12%
10%
8%
2%
15%
Lump Sum
Quantity
0
110,352
0
0
110,352
45,642
0
0
1
993,168
0.0
155,994
3
11
0
2,000
3,986
1
0
3,941
3941
0
1
of Subtotal
of Subtotal
of Subtotal
of Subtotal
of Subtotal
Unit Cost
$ 1.60
$ 9.99
$ 4.31
$ 21.56
$ 4.31
$ 10.55
$ 0.54
$ 6.97
$ 431,700.00
$ 0.01
$ 5,000.00
$ 0.58
$ 20,000
$ 4,000
$ 700
$ 38.51
$ 7.60
$ 389,000
$ 0.05
$ 2.00
$ 0.20
$ 10,000
$ 10,000
Subtotal
Subtotal
Cost
$0
$1,102,607
$0
$0
$475,617
$481,528
$0
$0
—
$9,932
$0
$90,477
$60,000
$44,000
$0
$77,022
$30,296
$389,000
$0
$7,882
$788
$0
$15,000
S 6,534,887
$784,186
$653,489
$522,791
$130,698
$980,233
$3,071,397
2008 Cost
$0
$1,309,100
$0
$0
$564,689
$571,707
$0
$0
$ 431,700.00
$11,792
$0
$107,421
$60,000
$44,000
$0
$81,695
$35,970
$412,603
$0
$7,882
$936
$0
$15,000
S 7,804,028
$784,186
$653,489
$522,791
$130,698
$1,170,604
$3,261,768
Reference
8 oz BoomEnviro (.80); 0.80 labor (Means (2005) = .74)
02700 200 1 100 Means 150 mm crushed stone
30 mil BoomEnviro (3.51); 0.80 labor (Means (2005)= .74)
33080507 Means (2005)
30 mil BoomEnviro (3.51); 0.80 labor (Means (2005)= .74)
17030430 Means (2005)
33080523 Means (2005)
17030422 Means (2005)
2008 Vendor Quote
33080585 Means (2005) water by truck
RBirdSection4 cost tables w S7[(S3)Excavation offsite]
0222002267200 Means (2005)
Engineering Judgment
Engineering Judgment
Engineering Judgment
See tab Utilities
10 x PolyLineAnchor Trench 33080503 Means (2005)
See tab Runoff
0293003080400 Means (2005)
Engineering Judgment
1 sign / 500 ft of perimeter; $100 installed = $0.20/ft
Engineering Judgment
Past Project Experience
Past Project Experience
Past Project Experience
Past Project Experience
EPA 540-R-98-045
Cost Base
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2008
2008
2008
2007
2005
2007
2005
2008
2005
2008
2008
2008
2008
2008
2008
Appendix C-3 Cap Costs Asphalt Alt 2A
Cost-Asphalt Cap 2A
Page 2 of 10
-------
Appendix C-3
Asphalt Surface Cap Cost Estimate
Line Item
Operation and Maintenance
Air Quality Monitoring, 4/y, 2 hr ea
Periodic Inspection (4/yr, engr, 8 hr ea)
Burrowing Animal Control
Mowing / Vegetation Support
Cap Repairs (asphalt patch, 10%/yr)
Fence Repairs (10%)
Reporting (1/yr)
Total
Present Value of O&M
Unit
TOTAL IN
hrs
hrs
Acre
Acre
sqyd
Linear Feet
hrs
Quantity
STALLED
8
32
11,035
399
24
Unit Cost
COST
$ 100.00
$ 100.00
$ 2.00
$ 15.00
$ 100.00
Northern Area Costing Estimation
Demolition Charges
Demolition Charges with Project Support
Cap Construction Charges w/o Demolition
Per Acre Cap Construction Costs w/o Demolition
Estimated Northern Area Cap Construction Cos
t
$2,761,468
$4,059,357.28
$7,006,438.35
$307,299.93
$430,219.90
Cost
$9,606,284
$ 800
$ 3,200
$22,070
$5,979
$ 2,400
$ 34,450
$529,579
2008 Cost
$11,065,796
$ 800
$ 3,200
$ 22,070
$ 7,809
$ 2,400
$ 36,280
$557,707
$11,623,502
Reference
engg estimate
engg estimate
engg estimate
17020701 Means (2004) + $4/ft material allowance
engg estimate
Cost Base
2008
2008
2008
2004
2008
Appendix C-3 Cap Costs Asphalt Alt 2A
Cost-Asphalt Cap 2A
Page 3 of 10
-------
Appendix C-3
Asphalt Surface Cap Cost Estimate
Excav
Length
1200
ition Geome
Depth
4
;try (ft)
Width
o
3
Means gave cost for 6" line =
Excavation Geometry (ft)
Length
2000
Excav
Length
5090
Depth
4
ition Geome
Depth
4
Width
o
3
;try (ft)
Width
o
J
Volume
CY
533
$ 36.00
Volume
CY
889
Volume
CY
2,262
Cost
$/CY
$ 5.65
$ 2.83
$ 8.48
$ 4,520
$ 3.77
/LF
Cost
$/CY
$ 5.65
$ 5,022
$ 2.51
$ 38.51
Cost
$/CY
$ 5.65
$ 2.83
$ 8.48
$ 19,172
$ 3.77
Potable Wat
er Line Rem
oval
General excavation from Means for 0.5 CY Excavator
Added cost for buried pipe as a percentage =
Sum
Above sum divided by linear feet
Potable Water
Line RePlac
ement
General excavation from Means for 0.5 CY Excavator
Excavation Cost
Excavation $/LF
Total $/LF
Abandoned Ut
ility Line Re
moval
General excavation from Means for 0.5 CY Excavator
Added cost for buried pipe as a percentage =
Sum
Above sum divided by linear feet
50%
50%
Eng Judgment
Eng Judgment
Appendix C-3 Cap Costs Asphalt Alt 2A
Utilities
Page 4 of 10
-------
Appendix C-3
Asphalt Surface Cap Cost Estimate
Means gives installation cost for 25' pole as
Assume removal and replacement of each pole
Assume removal at same rate as installation =
Cost factor to re-install within landfill =
o
J
Overhead
$ 800.00
$ 800.00
$ 2,400.00
$ 3,200.00
Power / Phor
each
each
ic
10 power poles
Total cost per pole used in estimate
13.7kvaandphone
Appendix C-3 Cap Costs Asphalt Alt 2A
Utilities
Page 5 of 10
-------
Appendix C-3
Asphalt Surface Cap Cost Estimate
Desij
Cover thickness - total (b)
Cover slope (%)
*n Paran
Equivalent radius of area covered
icter
=
=
s
1.71
0.50%
560
ft
ft
Soil
Stone
Quantity Assumptions
Excavation Swell Factor (%) :
Compaction Shrink Factor (%):
Excavation Swell Factor (%) :
Compaction Shrink Factor (%):
25%
25%
15%
15%
Base case - No excavation
Maximum height ( h )
Fill Height (k)
e value to calculate cap vol
f-radius to calculate cap vol
Fill Volume
4.51
2.80
341
901
ft
ft
ft
ft
Cap material volume
Maximui
n height (
Fill Height (k)
h)
e value to calculate cap vol
f-radius to calculate cap vol
Fill Volume
3.51
1.80
531
1091
ft
ft
ft
ft
Cap material volume
Perimeter dig depth (d)
Excavation width
Fill Radius
1
200
360
ft
ft
ft
Excavation Volume
Site-wide dig depth (w)
1
ft
Site-wide dig volume
Soil Cap Layer
Surface
Hot Mix Base
Base Course
Geomembrane
Drainage
Geomembrane
25mm
40mm
150mm
Thick
ft
0.083
0.131
0.492
0.0
X
-
Cover thickness + (slope * equivalent radius)
Sope * esuivalent radius
Eq radius * cover thickness / fill height
Eq radius + e- value
Fill Volume = 0.333 it (Fill ht)(Fill radius squared)
.337ih*fradiusA2 - .337ik*radiusA2 - 0.57ib(fradiusA2-radiusA2)
Cover thickn
3ss + (slope *
Sope * esuivalent radius
Se
equivalent ra
Eq radius * cover thickness / fill height
Eq radius + e- value
lected Seen
dius)
Fill Volume = 0.333 n (Fill ht)(Fill radius squared)
ario for Co
.337ih*fradiusA2 - .337ik*radiusA2 - 0.57ib(fradiusA2-radiusA2)
perimeter dig depth / slope
Equivalent radius - excavation width
Cap
Volume
(cy)
58,394
sting
Cap
Volume
(cy)
58,394
.337id*eqradiusA2 - .337id*fill radiusA2 - 0.57id(eqradiusA2-fill radiusA2)
7rw*fradiusA2
Material
Aphalt surface 1 inch
~ 1.6-inch asphalt
aphlt-tretd permble base
Sand and gravel
Estimated
Vol (cy)
2,853
4,479
16,831
0
0
0
Vol (cy) Corrected
Perimeter
Excavate
Volume
(cy)
Perimeter
Excavate
Volume
(cy)
10,705
Site-wide
Excavate
Volume
(cy)
Site-wide
Excavate
Volume
(cy)
15,080
Interior
Excavate
Volume
(cy)
0
Adjust
Excavate
Volume
(cy)
24,173
For Compaction Shrink
Fill
Volume
(cy)
34,056
Fill
Volume
(cy)
24,127
2,853 Note - asphalt costed in sq yd based on site area
4,479 Note - asphalt costed in sq yd based on site area
19,801 Note - asphalt costed in sq yd based on site .
0
irea
Fill
Export (-)
Import (+)
(cy)
Fill
Export (-)
Import (+)
(cy)
(45)
Excavtn
to Fill
Ratio
0.00
Excavtn
to Fill
Ratio
1.00
Appendix C-3 Cap Costs Asphalt Alt 2A
Dig and Cap Qty
Page 6 of 10
-------
Appendix C-3
Asphalt Surface Cap Cost Estimate
Infiltration Barrier
Geomembrane
Gas Collection
Maximm
n height (
Fill Height (k)
Total =
h)
e value to calculate cap vol
f-radius to calculate cap vol
Fill Volume
0.0
1.0
1.71
3.2558
1.55
616
1176
-
-
X
ft
ft
ft
ft
Cap material volume
Perimeter dig depth (d)
Excavation width
Fill Radius
1.25
250
310
ft
ft
ft
Excavation Volume
Site-wide dig depth (w)
0
ft
Site-wide dig volume
Soil
Sand and gravel
absent
included
Cover thickn
sss + (slope *
Sope * esuivalent radius
0
0
34,232
58,394
Alte
equivalent ra
Eq radius * cover thickness / fill height
Eq radius + e- value
rnative Exc
dius)
Fill Volume = 0.333 TI (Fill ht)(Fill radius squared)
0
45,642
58,394
avation Sc<
.337ih*fradiusA2 - .337ik*radiusA2 - 0.57ib(fradiusA2-radiusA2)
perimeter dig depth / slope
Equivalent radius - excavation width
marios
Cap
Volume
(cy)
58,394
.337id*eqradiusA2 - .337id*fill radiusA2 - 0.57id(eqradiusA2-fill radiusA2)
7rw*fradiusA2
Perimeter
Excavate
Volume
(cy)
15,817
Site-wide
Excavate
Volume
(cy)
0
Adjust
Excavate
Volume
(cy)
14,828
Fill
Volume
(cy)
5,777
Fill
Export (-)
Import (+)
(cy)
(9,051)
Excavtn
to Fill
Ratio
2.57
Appendix C-3 Cap Costs Asphalt Alt 2A
Dig and Cap Qty
Page 7 of 10
-------
Appendix C-3
Asphalt Surface Cap Cost Estimate
Design Rainfall (in/hr)
Target Velocity (ft/sec)
Area
ac
11.4
11.4
C
0.45
0.95
Rainfall
(in/hr)
1.5
1.5
1.5
2.5
Q
cfs
7.695
16.245
Estimated linear feet of pipe
Number of manholes
Manhole spaciing (ft)
Target
Vel
ft/sec
2.5
2.5
4000
10
400
Req'd
Area
(sqft)
3.078
6.498
Req'd
Diameter
(ft)
2.0
2.9
at unit price of
Req'd
Diameter
(in)
23.8
34.5
$ 500.00
Cost/LF
Pipe
53.5
96
Total /LF
w/mhole
$ 54.75
$ 97.25
Cost
$219,000
$ 389,000
Manhole Costs
equates to per foot
$ 1.25
Means
Means
2007
2007
Appendix C-3 Cap Costs Asphalt Alt 2A
Runoff
Page 8 of 10
-------
Appendix C-3
Asphalt Surface Cap Cost Estimate
Total Area
Acres
22.8
SqFt
970,824
Acreage
stated in FS
Screening
Report
Demolition Quantities
Item
Warehouse
NE Tank Farm
Tank Farm Bldg
WWTP
Maint/Locker Bldg
Main Process Area
Rail Siding
Loading Area Tanks
Eastern Process/Glycol
Western Road
Center Road
Road to WWTP
Remaining Area
Length
250
266
100
200
150
200
400
400
300
800
800
1300
Total
Area
SqFt
647,024
Width
200
200
40
200
40
300
60
80
50
15
15
12
Subtotal
Structure
Footprint
%
10
Totals
Bldg
?
1
0
0
0
0
0
0
0
0
0
0
0
50,000
Demo
Area
SqFt
64,702
Area
SqFt
50,000
53,200
4,000
40,000
6,000
60,000
24,000
32,000
15,000
12,000
12,000
15,600
323,800
388,502
Concrete
Thick(ft)
5
2
0.5
1.5
0.5
1.5
1.5
1.5
% Cover
100
100
100
70
100
60
0
70
70
0
0
0
CY
9,259
3,941
74
1,556
111
2,000
0
1,244
583
0
0
0
18,769
Concrete
Thick(ft)
1
% Cover
20
Cubic Yd
479
19,248
Asphalt
% Cover |Sq Yard
0
0
0
0
0
0
0
0
0
90
90
100
0
0
0
0
0
0
0
0
0
10800
10800
15600
37,200
Asphalt
% Cover
30
SqYard
2,157
39,357
Appendix C-3 Cap Costs Asphalt Alt 2A
Demolition Qtys
Page 9 of 10
-------
Appendix C-3
Asphalt Surface Cap Cost Estimate
Disposal Quantities
Assume all debris is non-hazardous.
Assume all tanks are recycled.
Debris Volume Expansion Factors (Ratio of Disposal Volume to In-Place Volume)
Material
Concrete
Wood
Tile
Based on P
Factor
2.3
4.0
3.5
5.0
1.2
lot Demolitic
Average
mProjectR
ocky Moun
Light Wood (Offices, etc)
Significant Structure Support
Estimated Cubic Yards based on Square Footage:
Type
Warehouse
NE Tank Farm
Tank Farm Bldg
WWTP
Maint/Locker Bldg
Main Process Area
Rail Siding
Loading Area Tanks
Eastern Process/Glycol
Western Road
Center Road
Road to WWTP
Concrete
Asphalt
Ratio:
cy/sqft
0.10
0.02
0.05
0.10
0.05
0.05
0.01
0.05
0.05
0.05
0.05
0.05
Assume thick (ft)=
0.5
tain Arsena
Disposal
Qty (cy)
5,000
0
0
0
0
0
0
0
0
0
0
0
19,248
6,559
il
Reductio
0
40
40
50
40
Expand
Factor
2.4
2.0
2.
2.
2.
2.
2.5
2.
2.
2.
2.
2.
Bldg
2.3
2.2
n (%) < Transport
Sub-total
Total =
Landfill
Qty (cy)
12,000
0
0
0
0
0
0
0
0
0
0
0
12,000
44,270
14,431
70,701
Net Factor
2.3
2.4
2.1
2.5
0.72
Appendix C-3 Cap Costs Asphalt Alt 2A
Demolition Qtys
Page 10 of 10
-------
Appendix C-4
Soil Vapor Extraction (SVE) Cost Estimate
-------
Appendix C-4
SVE Cost Estimat
Standard Chlorine of Delaware
Soil Vapor Extraction System
COST ESTIMATE SUMMARY
Site: Standard Chlorine of Delaware Description:
Location: Delaware City, Delaware 330,000 SF, Estimated remedial target area (12 on-facility areas, 1 off-site area)
Phase: Feasibility Study 18 FT, Assumed ROI. On-facility SVE wells installed to a depth of 50ft. Assume an overlap of 10%.
Base Year: 2008 LTM for estimated 2 year period
Date: 6/3/2008 Revised 5/8/2009
CAPITAL COSTS
DESCRIPTION
SVE Construction
Mobilization/Demobilization
Extraction & Conveyance Systems
Pilot Test
Well Installation (2" PVC with 10 slot screen X 50' deep)
Trenching and Backfill (31 wide x 3' deep)
Piping Installation (10" Diameter)
Piping Installation (2" Diameter)
Pipe Fittings
Erosion and Sediment Control
Subtotal
Soil Vapor Extraction System
SVE rotary claw system capable of 3,000 scfm at 1 0" Hg
Manifold with seven influent legs
Pneumatic activated Solenoid Valves
Air/water separator
Water Transfer Pump
Air to air heat exchanger
Air supply compressor
Control Equipment
Telemetry
Startup Assistance
Shipping
Subtotal
Remediation Building
Vapor Treatment System
GAC vessels
Granular Activated Carbon
Delivery & Installation
Subtotal
Monitoring System
Monitoring Wells (60' deep)
Well Development
Vapor Monitoring Probes (45' deep)
Subtotal
Startup/Performance Testing
Start-up and Testing
CONSTRUCTION SUBTOTAL
Contingency
SUBTOTAL
DESIGN, PERMITTING, REGULATORY (LABOR AND MISC EXPENSES)
G & A, Program Mngmt, Fee
Workplan/Remedial Design
Permits
Project Management/QC
Construction Oversight
Construction Completion Report
SUBTOTAL
TOTAL CAPITAL COST
QTY
1
1
357
17000
16600
400
1
1
1
1
7
1
1
2
1
1
1
1
1
1
1
1
18,000
1
20
20
20
1
15%
20%
15%
1%
5%
15%
1
UNIT
LS
LS
EA
LF
LF
LF
LS
LS
LS
LS
LS
LBS
LS
EA
EA
EA
LS
LS
UNIT
COST
$25,000
$50,000
$5,000
$38.85
$24.50
$4.40
$25,000
$15,000
$271,151
$80,000
$17,000
$1.07
$4,500
$10,000
$350
$6,000
$23,000
$4,296,194
$4,296,194
$4,296,194
$4,296,194
$4,296,194
$50,000
I
TOTAL
$25,000
$50,000
$1,785,000
$660,450
$406,700
$1,760
$25,000
$15,000
$2,968,910
$271,151
$80,000
$17,000
$19,260
$4,500
$40,760
$200,000
$7,000
$120,000
$327,000
$23,000
$3,735,821
$560,373
$4,296,194
$859,239
$644,429
$42,962
$214,810
$644,429
$50,000
$2,455,869
$6,752,000
NOTES
Drill rig, equip, etc., Includes HSP
Level D PPE
1 Pilot test to evaluate vacuum ROI, Re, etc.
SVE wells; 2" HOPE with 0.010 slot screen, 2" HOPE casing
VTANG quote via Matt Germon
ECI quote, HOPE (10" diameter)
ECI quote. Condensate Discharge to onsite treatment plant
sample ports, etc.
Including hay bales and/or silt fencing
National Turbine model NT1 22607
MLEE 480 gallon vapor liquid separator
Gould's N PE model 2ST - maximum flow rate of 60gpm @ 50' TDH
Xchanger Inc. with EXP motor
Champion model HR3-6. Included for pneumatic valve operation
PLC Series Direct Logic programmable logic controller & system alarms
MLE model SL-P wireless remote access
Maple Leaf Environmental Equipment Quote #801 249RO
Slab on grade, insulated, with lights, heat, and ventilation, estimated
Cost estimated from information received from Carbon Air.
Capacity of vessel is 18,000 Ib. Max flow 10,000 cfm
Virgin coconut based activated carbon, 4-8 mesh size, assumed 104lbs/lb usage
rate (replacement in O&M costs)
Estimated
2" SCH 40 316 stainless with 0.010" slot screens
1"SCH 40 31 6 stainless, three nested completions within same borehole
Equipment commissioning, performance testing, initial operations
Allowance for unidentified scope items
I
Appendix C-4 FS SVE Cost 2009 Revision
Standard Chlorine SVE Cost
-------
Appendix C-4
SVE Cost Estimat
Standard Chlorine of Delaware
Soil Vapor Extraction System
OPERATIONS AND MAINTENANCE COST
COST ESTIMATE SUMMARY
Years of operation 2
DESCRIPTION
Groundwater Monitoring
Groundwater Samples
QC Samples
Sampling Labor
Consumables
Data Validation and Management
Reporting
SUBTOTAL
Allowance for Misc. Items
SUBTOTAL
Contingency
SUBTOTAL ANNUAL COST
GAC Replacement
RCRA Characterization
GAC removal & containerization
Granular Activated Carbon
QTY
20
14
60
1
10
32
20%
15%
1
2
37,960
UNIT
EA
EA
MRS
LS
MRS
MRS
LS
LS
LBS
UNIT
COST
$150
$150
$85
$1,000
$85
$85
$1,000
$4,500.00
$1.07
TOTAL
$3,000
$2,100
$5,100
$1,000
$850
$2,720
$14,770
$2,954
$17,724
$2,659
$20,000
$1,000
$9,000
$40,617
NOTES
semi-annual (twice/year) sampling of 10 wells
VOC Analysis only
(Per Year: 4MS/MSD,4dup,3TB.3EB)
3 hrs/sample
0.5 hrs/sample
10% Scope + 20% Bid
TCLP VOC analysis, 2 total
2 change outs per year assumed
Virgin coconut, 4-8 mesh size, assumed 104lbs/lb usage rate
T&D as RCRA haz waste above treatment standards (requires treatment prior to
GAC Transport & Disposal
SUBTOTAL ANNUAL COST
SVE System O&M
Routine System Monitoring
Equipment maintenance
Analytical Costs - Vapor
Analytical Costs - Water
Monitoring Equipment
Electricity
Other Expenses (Shipping, supplies, etc.)
Quarterly Report
Subtotal
PM and Administrative
Contingency
SUBTOTAL ANNUAL COST
PRESENT VALUE ANALYSIS
COST TYPE
CAPITAL COST
O&M COST (SVE Operation, GAC Replacement
TOTAL PRESENT VALUE
37,960
240
1
180
12
12
12
12
1
Discount Rate =
GW Sampling)
LBS
HR
LS
EA
EA
Mo
Mo
Mo
LS
10%
15%
5.0%
YEAR
0
0-2
$2.00
$90
$14,000
$235
$150
$500
$10,281
$300
$60,000
ANNUAL
COST
$6,752,000
$487,537
I
$75,920
$126,537
$21,600
$14,000
$42,300
$1,800
$6,000
$123,368
$3,600
$60,000
$272,668
$27,267
$40,900
$341,000
PRESENT VALUE
$6,752,000
$906,532
$7,700,000
landfill. Estimate based on existing contract for this service
(1 person, 2 times per month, 10 hours a day)
estimate for oil, replacement parts (belts, filters, gauges), misc tools & equip
TO-14 analysis (1 per area plus total influent & effluent (15 sam
8260 analysis for condensate discharge
PID, GEM 2000 (LEL, O2, CO2, CH4), vapor sampling pump
estimate based on power consumption, see worksheet
estimate
4 reports
does not include system decommissioning
NOTES
I
pies) per month
Appendix C-4 FS SVE Cost 2009 Revision
Standard Chlorine SVE Cost
-------
Appendix C-4
SVE Cost Estimate
Standard Chlorine of Delaware SVE Treatment Areas
Soil Vapor Extraction System
Site: Standard Chlorine of Delaware
Location: Delaware City, Delaware
Phase: Feasibility Study
Base Year: 2008
Date: 6/3/2008
Treatment Area
Area
ApproximateNuinber of
SVE Points per
Treatment Area
SVE Extraction
Total Depth
(feet)
On-Facility Area
Vnit
Soil PRO On-Facility
Contamination
Volume for Soil Gas PRO On-
Facility Contamination
Off-specification product
PCB/dioxin concentration area
(RAS-1)
Catch basin #1 (RAS-2)
Former rail siding and loading
area (RAS-3/RAS-7)
Warehouse and the area to
the north of the warehouse
(RAS-4)
Facility storm drains
Drum cleaning area (RAS-5)
Northern end of eastern
drainage ditch (RAS-6)
Former wastewater treatment
plant (RAS-8)
Chemical process area (RAS-
9/RAS-10)
1986 tank collapse area
Northeast tank farm
Total On-Facility
Contamination
Square Footage
815,710
.
(feet)
10,000
10,000
65,000
60,000
5,000
10,000
10,000
35,000
50,000
10,000
65,000
330,000
11
11
70
65
5
11
11
38
54
11
70
357
50
50
50
50
50
50
50
50
50
50
50
.
Off-Site Area
Maximum "Northern Area"
Contamination
Total
60,000
390,000
59
416
50
-
Notes:
Assumed ROI is 18 feet from each SVE point
AreaofROI = PI(r2)
Surface area influenced by each SVE point = 1017.36 square feet
Northern Area Not Considered in Costing
Appendix C-4 FS SVE Cost 2009 Revision
Treatment Areas
Page 3 of 5
-------
Appendix C-4
SVE Cost Estimate
SCO SVE Design Basis & Assumptions
SVE Radius of Influence and Construction
The vadose zone (0-50-ftbgs) consists of unconsolidated sand and gravel with pockets of silt and clay with a permeability of 103to 10~2
cm/sec.
There are no utility conflicts. Estimate does not cost provisions for removing or temporarily relocating utilities.
All excavated soil is suitable to be used as backfill or can be incorporated into the area being capped.
An assumed radius of influence of 18ft has been used to calculate the number of required SVE extraction points per treatment area.
An air flow rate of 60 scfm per well is assumed to be sufficient to achieve the ROI at each SVE well.
To treat the entire surface area it is suggested that 357 SVE extraction points are utilized throughout the treatment area assuming a 10%
overlap of the well ROIs.
To achieve a reasonable total air flow rate, the SVE unit has been designed to automatically cycle between 7 treatment areas.
Approximately 42-60 SVE extraction points are located per area.
The average flow rate of the SVE system is assumed to operate at 3,000 scfm (average 50 SVE points per treatment area X 60 scfm)
10" diameter HOPE is assumed to convey extracted vapor from the treatment areas to the central SVE system to minimize head loss.
It is assumed that condensate collected from the SVE during normal operation would be pumped to and treated at the on-site water
treatment plant
Each SVE extraction point will consist of 2" diameter HOPE riser and screen to a depth of 50ft
GAC Treatment
GAC cost and usage rate estimates have been completed in conjunction with Carbonair's GAC usage model using soil gas
concentrations from each treatment area
In order to account for lower concentrations during the two year treatment period, it has been assumed that the long term average
concentration would be 25% of the original concentrations.
Effluent air temperature is assumed to be equal to ambient conditions
New virgin coconut based GAC has been chosen over the less effective and more costly "reactivated" versions of GAC
Using average soil gas concentrations from each treatment area (see below), the initial daily usage rate of carbon is 416 Ib/day, and long
term average is 104 Ib/day
A Carbonair RO-10 vessel or equivalent with a 18,000 Ib capacity and 10,000 cfm max flow rate is recommended based on the
assumptions.
The approximate soil gas contaminants of concern are:
Benzene range: 120-40,000 (average 1,200) ppbv
Carbon Tetrachloride: 75-6,600 (average 1,495) ppbv
Chloroform: 50 - 43,000 (average 6,200) ppbv
Tetrachloroethene: 66 -1,800 (average 410) ppbv
1,2 Dichlorobenzene: 38,000 - 43,000 ppbv
1,4 Dichlorobenzene: 120 - 39,000 (average 4,800) ppbv
Trichloroethylene: 7-310 (average 83) ppbv
Chlorobenzene: 2,700 - 160,000 (average 71,000) ppbv
Appendix C-4 FS SVE Cost 2009 Revision Design Basis Page 4 of 5
-------
Appendix C-4
SVE Cost Estimate
Equipment Power Requirements
SVE blower 200 HP
A/WTranferPump 1.5 HP
Heat exchange unit 4 HP
Air Compressor 3 HP
Subtotal 208.5 HP Brake power, including pump efficiency.
Subtotal 155 KW Conversion of HP to kW; 1 HP = 0.7457 kW.
Enclosure Heater 1 KW Assumed average
„ . . -,.-„. Factor to account for that fact that not all motors are continuous
Service Average 75%
3 service
Average 117 KW
Electricity cost 0.12 $/KW-Hr
Monthly Power cost $10,281 Based on continuous service
Appendix C-4 FS SVE Cost 2009 Revision Electric Calcs Page 5 of 5
-------
Appendix C-5
In Situ Thermal Desorption (ISTD) Cost Estimate
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Site-
New Castle County, Delaware
APPENDIX C-5
IN SITU THERMAL DESORPTION COST ESTIMATE
Dimensions and Properties
Treatment Area
Upper depth of treatment
Lower depth of treatment
Treatment volume
Porosity
330,000
-
50
610,000
0.4
square ft
ft below grade
ft below grade
cubic yards
assumed
Borings and Wells
Number of HO wells
Number of HV wells
Number of monitoring holes
2800
1400
75
Utility Estimate
Shake-down
Heat-up to lOOoC
Boiling phase
Heat-up to 300oC
Cooldown
Total
Days
45
117
267
309
45
783
Power Usage
Average
Power Usage,
kW
150
22,506
22,506
22,506
150
Total Power,
kWh
162,000
63,179,574
143,986,185
167,240,049
162,000
374,730,000
Natural Gas Usage
Average
Rate,
MM BTU/hr
5
2.5
1.25
1.25
5
Total, MM
BTU
5,400
7,017
7,998
9,288
5,400
35,103
Appendix C-5 FS ISTD Cost
U.S. EPA Region 3
Page Iof2
-------
HGL—Feasibility Study Report, Standard Chlorine of Delaware Site-
New Castle County, Delaware
Preliminary Cost Estimate
Design and Installation
Operation
Demobilization & other
Design and permitting
Mobilization
Drill + install wells (1)
Hydraulic barrier preparation
Vapo cover installation
Electrical construction (2)
Mechanical construction
Vapor and water treatment system
Commissioning
Maintenance hardware etc.
Labor, per diem
Power
Sampling and analysis
Waste and GAC
Caustic for scrubber
Gas for oxidizer
Rental and fees
Demobilization
Reporting
Travel and office/engineering support
Licensing fees
Contigency and indirect cost
Power (3)
Total costs
Volume, cubic yards
$ per cubic yard
Total Cost, USD
$230,000
$886,000
$22,125,000
not necessary
$2,370,000
$896,000
$1,280,000
$1,454,000
$234,000
$1,497,000
$1,728,000
$294,000
$312,000
$372,000
$1,005,000
$294,000
$1,162,000
$195,000
$44,969,000
$81,303,000
612,356
$133
NOTES:
(1) "Drill+install wells" includes ISTD heaters
(2) "Electrical constuction" includes ISTD power distribution
(3) Electrical power assumed at $0.12/kWhr
Cost estimate based on vendor quote
U.S. EPA Region 3
Appendix C-5 FS ISTD Cost
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