RECORD OF DECISION
WALKER MACHINE PRODUCTS, INC.
SUPERFUND SITE
COLLIERVILLE, SHELBY COUNTY, TENNESSEE
CERCLIS ID: TNN000410124
PREPARED BY:
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION 4
ATLANTA, GEORGIA
SEPTEMBER 2018
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RECORD OF DECISION
TABLE OF CONTENTS
Acronyms and Abbreviations
PARTI: DECLARATION 1
1.0 Site Name and Location 1
2.0 Statement of Basis and Purpose 1
3.0 Assessment of the Site 1
4.0 Description of Selected Remedy 1
5.0 Statutory Determinations 3
6.0 Data Certification Checklist 3
7.0 Authorizing Signature 4
PART 2: THE DECISION SUMMARY 5
1.0 Site Name, Location, and Brief Description ........5
2.0 Site History and Enforcement Activities 5
2.1 Site Operational History 5
2.2 Regulatory and Investigation History 6
3.0 Community Participation 10
4.0 Scope and Role of the Response Action 11
5.0 Site Characteristics 11
5.1 Conceptual Site Model ; 11
5.2 Overview of the Site 12
5.2.1 Geologic, Hydrogeologic, and Topographic Information 12
5.3 Sampling Strategy 13
5.4 Known or Suspected Sources of Contamination 13
5.5 Nature and Extent of Contamination . 14
5.5.1 NAPL Contamination , 14
5.5.2 Soil Contamination .....14
5.5.3 Groundwater Contamination 15
5.5.4 Sediment Contamination 16
5.5.5 Surface Water Contamination 16
5.5.6 Vapor Phase Contamination 16
5.5.7 Indoor Air Contamination 16
6.0 Current and Potential Future Land and Groundwater Uses 17
6.1 Land Uses 17
6.2 Ground and Surface Water Uses 17
7.0 Summary of Site Risks 18
7.1 Summary of the Human Health Risk Assessment 18
7.1.1 Identification of Chemicals of Concern 18
7.1.2 Exposure Assessment 18
7.1.3 Toxicity Assessment : 19
7.1.4 Risk Characterization 19
7.1.5 Uncertainties 22
7.1.6 Basis for Action 22
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. 7.2 Summary of the Ecological Risk Assessment 23
7.2.1 Risks Estimates to Aquatic Organisms 24
7.2.2 Risk Estimates to Terrestrial Organisms 24
7.2.3 Uncertainties .....24
7.2.4 ERA Conclusion 25
8.0 Remedial Action Objectives . 25
9.0 Description of Alternatives 26
9.1 Description of the Unsaturated Soil Zone (UZ) Remedy Alternatives 26
9.1.1 UZ Alternative 1: No Action... 27
9.1.2 UZ Alternative 2a: Soil Vapor Extraction (SVE) with Limited Air
Sparging 27
9.1.3 UZ Alternative 2b: Thermally Enhanced SVE with Limited Air
Sparging 28
9.1.4 UZ Alternative 3: Limited Soil Excavation with SVE 29
9.1.5 UZ Alternative 4: In-situ Chemical Oxidation (ISCO) and SVE 29
9.2 Description of the SSZ Remedy Alternatives 30
9.2.1 SSZ Alternative 1: No Action 31
9.2.2 SSZ Alternative 2: Groundwater Recovery and Treatment/Hydraulic
Containment 31
9.2.3 SSZ Alternative 3: ISCO 32
9.2.4 SSZ Alternative 4: Enhanced In Situ Bioremediation (EISB) with in situ
chemical reduction (ISCR) 32
9.2.5 SSZ Alternative 5: Biogeochemical Reductive Dehalogenation 34
9.3 Description of the Dilute Plume (DP) Remedy Alternatives 35
9.3.1 DP Alternative 1: No Action 35
9.3.2 DP Alternative 2: Groundwater Recovery and Treatment
(GR&T)/Hydraulic Containment 35
9.3.3 DP Alternative 3: EISB Passive Barriers with Horizontal Well 36
9.3.4 DP Alternative 4: Monitored Natural Attenuation (MNA) 37
9.3.5 Institutional Controls 38
9.4 Distinguishing Features of Each Alternative 39
10.0 Comparative Analysis of Alternatives . 43
10.1 Overall Protection of Human Health and the Environment 44
10.2 Compliance with ARARs 44
10.3 Long-Term Effectiveness and Permanence 46
10.4Reduce Toxicity, Mobility or Volume through Treatment 47
10.5 Short-Term Effectiveness 47
10.6Implementability 48
10.7Cost. , 48
10.8State Acceptance 49
10.9Community Acceptance 49
11.0 Principal Threat Waste (PTW) 49
12.0 Selected Remedy 49
12.1 Summary of the Rationale for the Selected Remedy 50
12.2Description of the Selected Remedy 51
12.2.1 Unsaturated Soil Zone 51
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12.2.2 Saturated Soil Zone 52
12.2.3 Dilute Plume 53
12.2.4 Institutional Controls 54
12.2.5 Cost Estimate for the Selected Remedy 55
12.2.6 Recommended Phasing 56
12.2.7 Estimated Outcomes of the Selected Remedy 57
13.0 Statutory Determination 58
13.1 Protection of Human Health and the Environment 58
13.2 Compliance with ARARs 58
13.3 Cost Effectiveness 58
13.4 Use of Permanent Solutions and Alternative Treatment Technologies to the
Maximum Extent Practicable 59
13.5 Preference for Treatment as a Principal Element 59
13.6 Five-Year Review Requirements 60
13.7 Documentation of Significant Changes 60
14.0 References 61
PART 3: RESPONSIVENESS SUMMARY 64
TABLES
Table 1 Occurrence, Distribution, and Selection of Chemicals of Potential Concern
in Soil
Table 2 Occurrence, Distribution, and Selection of Chemicals of Potential Concern
in Groundwater
Table 3 Occurrence, Distribution, and Selection of Chemicals of Potential Concern
in Sediment
Table 4 Occurrence, Distribution, and Selection of Chemicals of Potential Concern
in Indoor Air
Table 5 Risk Characterization Summary - Carcinogens in Surface Soil (Future
Resident)
Table 6 Risk Characterization Summary - Non-Carcinogens in Surface Soil
(Future Resident)
Table 7 Risk Characterization Summary - Carcinogens in Soil (Future
Construction Worker)
Table 8 Risk Characterization Summary - Non-Carcinogens in Soil (Future
Construction Worker)
Table 9 Risk Characterization Summary - Carcinogens in Groundwater (Future
Resident)
Table 10 Risk Characterization Summary - Non-carcinogens in Groundwater
. (Future Resident)
Table 11 Risk Characterization Summary - Carcinogens in Groundwater (Future
Industriial/Commercial Worker)
Table 12 Risk Characterization Summary - Non-Carcinogens in Groundwater
(Future Industrial/Commercial Worker)
Table 13 Risk Characterization Summary - Carcinogens in Groundwater (Future
Construction Worker)
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Table
14
Risk Characterization Summary - Non-Carcinogens in Groundwater
(Future Construction Worker)
Table
15
Risk Characterization Summary - Carcinogens in Sediment (Future
Resident)
-Table
16
Risk Characterization Summary - Non-Carcinogens in Sediment (Future
Resident)
Table
17
Risk Characterization Summary - Carcinogens in Indoor Air (Future
Resident)
Table
18
Risk Characterization Summary - Non-carcinogens in Indoor Air (Future
Resident)
Table
19
Risk Characterization Summary - Carcinogens in Indoor Air
(Current/Future Industrial/Commercial Worker)
Table
20
Risk Characterization Summary - Non-Carcinogens in Indoor. Air (Future
Resident)
Table
21
Cleanup Goals for Chemicals of Concern in Subsurface Soil
Table
22
Cleanup Goals for Chemicals of Concern in Groundwater
Table
23
Cleanup Goals for Chemicals of Concern in Indoor Air
Table
24
Potential Chemical-specific ARARs
Table
25
Potential Location-specific ARARs and TBC Guidance
Table
26
Potential Action-specific ARARs and TBC Guidance
Table
27
Cost Comparison of UZ Remedial Alternatives
Table
28
Cost Comparison of SSZ Remedial Alternatives
Table
29
Cost Comparison of DP Remedial Alternatives
FIGURES
Figure 1 Site Location Map
Figure 2 Site Layout Map
Figure 3 Town of Collierville Wellfield #1 Location
Figure 4 Generalized Conceptual Site Model
Figure 5 Human Health Conceptual Site Model
Figure 6 Ecological Conceptual Site Model
Figure 7 Contaminated Media Zone (CMZ) Boundaries
Figure 8 Surface Soil Exceedances
Figure 9 Subsurface Soil Exceedances
Figure 10 PCE in Soil Gas, 2011
Figure 11 PCE in Groundwater, 2015
Figure 12 Municipal Well Exceedances
Figure 13 Sediment Soil Exceedances
Figure 14 Vapor Phase Air Exceedances
Figure 15 Indoor/Ambient Air Exceedances
Figure 16 Site Wide Remedial Alternatives
APPENDICES
Appendix A Transcript of June 14, 2018 Public Meeting
Appendix B State of Tennessee Concurrence
Appendix C Selected Remedy Detailed Cost Estimate Sheets
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ACRONYMS AND ABBREVIATIONS
% percent
ADD average daily dose
amsl above mean sea level
AR Administrative Record
ARAR applicable or relevant and appropriate requirement
AST above ground storage tank
BaP benzo(a)pyrene
BiRD Biogeochemical Reductive Dehalogenation
Black & Veatch Black & Veatch Special Projects Corp.
bis below land surface
bey bank (in-place) cubic yards
CERCLA Comprehensive Environmental Response, Compensation, and Liability
Act
CERCLIS Comprehensive Environmental Response, Compensation, and Liability
Information System
CFR Code of Federal Regulations
CMZ Contaminated Media Zone
COC chemical(s) of concern
COPC chemical(s) of potential concern
CSF cancer slope factor
CSM conceptual site model
CVOC chlorinated volatile organic compound
DHC Dehalococcoides
DNAPL dense non-aqueous phase liquid
DP dilute plume
DPT direct push technology
DRO diesel range organics
EISB enhanced in-situ bioremediation
EPA U.S. Environmental Protection Agency
ERA Ecological Risk Assessment
EPC exposure point concentration
ESB equilibrium partitioning sediment benchmark
ESI Expanded Site Investigation
FEMA Federal Emergency Management Agency
FS Feasibility Study
ft foot or feet
ft2 square feet
FYR Five-Year Review
GAC granulated active carbon
GRO gasoline range organics
GR&T groundwater recovery and treatment
HDPE high density polyethylene
HH&E human health and environment
HHRA Human Health Risk Assessment
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HI
hazard index
HQ
hazard quotient
HRS
hazard ranking score
IC
institutional control(s)
ISCO
in-situ chemical oxidation
ISCR
in situ chemical reduction
LADD
lifetime average daily dose.
Langley
Langley Wire Cloth Products, Inc.
LDR
land disposal restrictions
LNAPL
non-aqueous phase liquid
MCL
Maximum Contaminant Level
Hg/kg
micrograms per kilogram
MNA
monitored natural attenuation
NAP
non-aqueous phase
NCP
National Contingency Plan
NPL
National Priorities List
O&M
operation and maintenance
ORP
oxidation reduction potential
OSHA
Occupational Safety and Health Administration
OSWER
Office of Solid Waste and Emergency Response
PAH
polycyclic aromatic hydrocarbon
PCE
tetrachloroethylene
PNOD
permanganate natural oxidant demand
PSG
passive soil gas
PTW
Principal Threat Waste
RA
remedial action
RAC
Remedial Action Contract
RAO
remedial action objective
RCRA
Resource Conservation and Recovery Act
RfC
reference concentration
RfD
reference dose
RGs
remedial goals
RI
Remedial Investigation
ROD
Record of Decision
SARA
Superfund Amendments and Reauthorization Act
Site
Walker Machine Products, Inc. Superfund Site
SS-RAL
Site-specific Risk-based Action Level
SSL
Soil Screening Level
SSZ
saturated soil zone
SVE
soil vapor extraction
SVOC
semi-volatile organic compound(s)
TBC
To Be Considered
TCA
trichloroethane
TCE
Trichloroethylene
TDEC
Tennessee Department of Environment and Conservation
TDH
Tennessee Department of Health
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TDOR Tennessee Department of Remediation
TEQ toxicity equivalent
T/M/V toxicity/mobility/volume
T/V toxicity/volume
UZ unsaturated soil zone
VI Vapor Intrusion
VOC volatile organic compound
Witt Witt International, Inc.
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PARTI: DECLARATION
1.0 Site Name and Location
This Record of Decision (ROD) is for the site-wide remedial action (RA) at the Walker
Machine Products, Inc. (Walker Machine) Superfund Site (Site) located in Collierville,
Shelby County, Tennessee (TN). The Site's Comprehensive Environmental Response,
Compensation, and Liability Information System (CERCLIS) identification number is
TNN000410124. The Site was listed on the National Priorities List (NPL) on May 12,
2014. The Site is bounded to the north by Washington Street; a vacant, wooded lot to the
east; to the south by an intermittent unnamed stream and railroad tracks owned and
operated by the Norfolk Southern Railway; and the former Witt International, Inc. (Witt)
facility to the west. Currently, the Walker Machine building is being used by a vehicle
customization business. The Witt building is occupied by a youth gymnastics academy
where children and workers are present, a children's dance studio, a party rental business,
a building supply, a specialty fastener business, and a newspaper distribution location.
2.0 Statement of Basis and Purpose
This decision document presents the selected remedy for the site-wide RA at the Site
which was chosen in accordance with the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA), as amended, 42 U.S.C. Section
9617, and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP)
as set forth in 40 Code of Federal Regulations (CFR) Part 300.430(f)(2). This decision is
based on the Administrative Record (AR) for the Site. This decision represents the final
remedy selected for the Site.
The State of Tennessee, as represented by the Tennessee Department of Environment and
Conservation (TDEC), is the support agency. In accordance with 40 CFR 300.430(f)(2),
TDEC has provided input during the remedial investigation (RI)/feasibility study (FS)
and the decision-making process. The State of Tennessee concurs with the Selected
Remedy.
3.0 Assessment of the Site
The response action selected in this ROD is necessary to protect the public health or
welfare or the environment from actual or threatened releases of hazardous substances
into the environment.
4.0 Description of Selected Remedy
The selected remedy addresses volatile organic compounds (including trichloroethene
and tetrachloroethene) that are present in soil, groundwater, and indoor air. The
contaminated soils under and south of the main building at the Site are considered to be
principal threat wastes at this Site. The contaminated soil is the source for contamination
in groundwater and indoor air. The selected remedy includes aggressive treatment of the
principal threat waste as well as treatment for the contaminated groundwater. A remedy
was selected for each of the three contaminated media zones (CMZs) designated at the
Site: Unsaturated Soil Zone (UZ); Saturated Soil Zone (SSZ); and Dilute Plume (DP).
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UZ Alternative UZ #2b - Thermally Enhanced Soil Vapor Extraction (TE-SVE) with
Limited Air Sparging which includes:
• SVE extraction wells to address contaminated soil under the building and south of
the building at depths between 5 to 55 feet below land surface (bis).
• Thermal enhancement (as needed) with heater borings spaced about 25-ft apart to
heat unsaturated soil from 5 to 55 feet bis. A target temperature of approximately
160°F is intended to promote enhanced volatilization and desorption.
• Air sparging wells screened at about 69 to 72 ft bis to address the highest levels of
shallow groundwater contamination which are found just south of the building.
• A trailer-mounted SVE system (with extraction blower, air/fluid separation
[knockout tank], and vapor phase carbon), and a trailer-mounted air sparge system
with air compressor and other appurtenances.
• Targeted soil excavation (about 900 cubic yards) near the oil/water separator, the
drum area, and near SE corner of building.
SSZ Alternative SSZ #5 - Biogeochemical Reductive Dehalogenation (BiRD)
• Installation of injection wells with screen intervals from 50 to 75 ft bis.
• Installation of groundwater recovery wells located at the foci of a hexagonal grid
approximately 30-feet from the injection wells.
• Injection/recirculation using approximately 33,000 pounds of carbon substrate
and 8,500 pounds of iron sulfate during the initial injection period of about 3
years. A secondary injection of amendments at 25% of the original dose during a
subsequent injection.
• Use of an injection manifold for the recirculation wells and an equipment trailer
with air stripping, bag filtration, granulated active carbon (GAC), and
supplemental water conditioning with an oxygen scavenger for water treatment
prior to reinjection.
DP Alternative DP #3 - Enhanced in-situ Bioremediation (EISB) via Passive Barrier
Wells and a Horizontal Well.
• Installation of injection wells along the west boundary of the Site for injection of
emulsified oil substrate. The wells would be screened from approximately 60 to
85 ft bis.
• Installation of a horizontal (directionally drilled) well under the adjacent
downgradient property at approximately 73 ft bis.
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• Injection of approximately 94,500 pounds of emulsified oil (or similar carbon
substrate) over an estimated injection period of 4 weeks.
• Addition of amendments to adjust the pH of groundwater as needed. The remedy
also assumes that bioaugmentation with beneficial bacteria would be required.
5.0 Statutory Determinations
Based on the information currently available, the EPA believes the selected remedy
meets the threshold criteria and provides the best balance of tradeoffs among the other
alternatives with respect to the balancing and modifying criteria. In compliance with
CERCLA Section 121(b) and Section 121(d), the selected remedy is protective of human
health and the environment, complies with federal and any more stringent state
requirements that are applicable or relevant and appropriate to the RA, is cost-effective,
and utilizes permanent solutions and treatment technologies to the maximum extent
practicable. The preference for treatment is satisfied given the active treatment measures
selected for each CMZ.
It is possible that this remedial action will ultimately allow for unlimited use and
unrestricted exposure after completion of the remedial action, but attainment of the
remedial action objectives and cleanup levels will take longer than five years to achieve.
A five-year review is required pursuant to CERCLA § 121(c) and NCP
§300.430(f)(5)(iii)(C). More specifically, a policy five-year review should be conducted
within five years of the date of construction completion.
6.0 Data Certification Checklist
The following information is included in the Decision Summary Section of this ROD.
Additional information can be found in the AR file for this Site.
• Chemicals of Potential Concern (COCs) and their concentrations (Tables 1 through
4).
• Baseline risk represented by the COCs (Section 7; Tables 6 through 20).
• COCs and their respective cleanup levels (Section 8, Tables 21 through 23).
• How source materials constituting principal threats are addressed (Section 11).
• Current and reasonably anticipated future land and groundwater use assumptions
(Section 6).
• Potential land and groundwater use that will be available at the site as a result of the
Selected Remedy (Section 6).
• Estimated capital, annual operation and maintenance (O&M), and total present
worth costs, discount rate, and the number of years over which the remedy cost
estimates are projected (Section 12.2.5).
• Key factors that led to selecting the remedy (i.e., describe how the Selected Remedy
provides the best balance of tradeoffs with respect to the balancing criteria,
highlighting criteria key to the decision) (Sections 12 and 13).
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PART 2: THE DECISION SUMMARY
1.0 Site Name, Location, and Brief Description
This Record of Decision (ROD) is for the Walker Machine Products, Inc. (Walker
Machine) Superfund Site (Site) located in Collierville, Shelby County, Tennessee (Figure
1). The Comprehensive Environmental Response, Compensation, and Liability
Information System identification number for the Site is TNN000410124. The Site
property is approximately 5 acres in size. Walker Machine manufactured precision
fabricated metal products (also referred to as automated machine screw products) from
1965 until about 2002. The facility is zoned general industry (Collierville, 2016). Land
use immediately surrounding the Walker Machine property is general industry with
medium to high residential zoning north and south of the Site.
Current site features include a metal and concrete manufacturing building surrounded by
concrete parking and storage pads to the north and south, a metal storage building to the
east, and gravel cover in between the two buildings. A hexagonal-shaped concrete pad is
located southeast of the manufacturing building. This pad once contained an above
ground storage tank (AST) where used solvent, that had been filtered to remove oil and
metal shavings, was stored. Adjacent to the concrete pad is a drainage (overflow) pond
that was used to contain spills from the AST. An oil/water separator (below ground tank),
which also appeared to receive solvent waste, is located approximately 35feet (ft) south
of the manufacturing building. Dilapidated drums (one drum was labeled TCE) and other
drum parts were in the wooded area on the property, south of the manufacturing building
(Figure 2). The City of Collierville owns five municipal well fields north and southwest
of the Site. Wellfield #1 is located approximately 0.6 miles west/northwest of the Site
(Figure 3).
The EPA is the lead agency for the cleanup of the Site and TDEC is the support agency.
To date, the EPA has financed activities at the Site, including an emergency response
action and the RI/FS.
2.0 Site History and Enforcement Activities
2.1 Site Operational History
Walker Machine manufactured precision fabricated metal products (also referred to as
automated machine screw products) from 1965 until about 2002 (Shelby County, 2016).
Hazardous waste permits list an operational date as early as 1953 (Walker Machine
Products, Inc., 1987). However, buildings are not present on the Site property in aerial
photos taken prior to 1963. Site operations between 2002 and 2005 are unclear. In 2005,
the property was purchased from Walker Machine by Langley Wire Cloth Products, Inc.,
(Langley) who began operations to manufacture wire cloth and perforated metal products
in 2006. Langley used small amounts of trichloroethylene (TCE) and other solvents until
2012, and all solvents used were reclaimed and recycled (Tennessee Department of
Remediation [TDOR], 2012). Langley vacated the building in March 2016 and the
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property remained vacant until it was purchased in August 2016 by 901 Customs. 901
Customs is currently operating a custom vehicle customization business at the Site.
The processes of manufacturing screw products at Walker Machine likely included the
cutting/conversion of raw materials such as carbon steel, copper and brass, and alloy steel
component parts and metal chips.
A broad range of 14 machining operations were likely used to configure the raw material
(bar stock) into a component part. During machining operations, cutting oils and coolants
are used to reduce friction, hold down temperature, protect the work piece from
corrosion, and flush away chips. The chips generated from machining operations are
typically recovered, treated to remove oils, and sold to scrap dealers. Solvents were used
to clean the parts and to ensure that the parts were free of oil, film, and chips.
The use of cutting oil and CimCool Five Star 40 coolant was documented during an
inspection at the active Walker Machine facility (EPA, 2013). These types of cutting oil
and coolant were typically mineral oil-based products. Walker Machine also used
solvents (mineral spirits and 1,1,1-trichloroethane [1,1,1-TCA]) in their process. Mineral
spirits were used to clean finished metal products. Brass parts were cleaned in 1,1,1-
TCA. Other industry typical solvents include tetrachloroethylene (PCE), TCE, methyl
ethyl ketone, acetone, and carbon tetrachloride. Walker Machine filtered used solvent to
remove oil and metal shavings and stored it in the AST after use. The solvents were then
reused for cleaning bolts (Tennessee Department of Health [TDH], 1987). An oil/water
separator was used by Walker Machine Products, Inc. and likely received solvent waste
as well. The oil/water separator still exists onsite, but was not used by Langley (TDEC,
2012).
2.2 Regulatory and Investigation History
The regulatory and investigation history for the Walker Machine Site is discussed below
and summarized in table on page 9.
In September 1987, the Tennessee Department of Labor, Divisions of Occupational
Safety and Health Administration [OSHA] conducted an inspection at the Walker
Machine facility. OSHA personnel observed spent solvent that had been discharged to the
ground and into a sewer drain located in the rear of the building (TDH, 1987).
In July 2007, TDOR conducted a Pre- CERCLIS Screening Investigation at the Site,
including the collection and analysis of subsurface soil, sediment, and groundwater
samples. Groundwater samples were collected from monitoring wells and municipal
wells, A sample was also collected from the oil/water separator.
During the Pre-CERCLIS screening investigation, PCE was detected at 590 ug/1 from a
monitoring well adjacent to the oil/water separator. PCE was also detected in one
subsurface soil sample from that same location. Vinyl chloride, cis-l,2-dichloroethene
(cis-l,2-DCE), and methyl ethyl ketone were detected in the sample collected from the
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oil/water separator. Based on these sample results TDOR recommended no further action
at the Site.(TDEC, 2008).
In March 2009, TDOR conducted a Site Investigation (SI) at Witt. Witt is located
adjacent to the western boundary of the Walker Machine Site and manufactured
commercial heat transfer equipment at the Washington Street facility from 1961 to 1999.
In the process of assembling air conditioning units, aluminum sheeting is stamped and
assembled with copper tubing to form air heat exchangers. Stamping and forming oils
and dirt are removed from these parts prior to final assembly. TCE was used as a primary
solvent in degreasing and cleaning parts during operations. The purpose of the 2009 SI
was to determine if any possible releases of contaminants from the Witt facility posed a
threat to human health and the environment, and to assess conditions of contaminants
migrating from the Walker Machine Products Site. The 2009 SI also included
investigation of a suspected former drum storage area located along the northwest edge of
the western side of the Witt building. PCE, TCE, and their byproducts were detected in
groundwater samples collected from wells upgradient of the Witt building, indicating that
the source of the contamination was the Walker Machine property. Due to groundwater
contamination above federal maximum contaminant levels (MCLs) and proximity to the
Town of Collierville Wellfield #1, TDOR recommended that further investigation be
conducted at the Walker Machine Site.
In 2009, TDOR conducted a Site reassessment (TDEC, 2010) to further define the extent
of groundwater contamination at the Walker Machine facility and to fill in data gaps to
the south of the Site by installing additional monitoring wells. Groundwater sampling of
the new wells at the Walker Machine property and those installed at Witt in 2008
indicated the presence of contaminants in all wells at levels similar to those in 2008.
Additional data was collected by TDEC in April 2011 as part of a Site Inspection (SI)
(TDEC, 2011). VOCs were detected in all groundwater samples at concentrations
exceeding MCLs. In 2011 TDOR also conducted a passive soil gas (PSG) study, which
included collection of soil samples to confirm the PSG results. Of the 30 locations
sampled, PCE was detected in 23 locations and TCE was detected in 19 locations. The
main occurrence of VOCs was around the southern side building and south towards the
property line. PCE was more prevalent to the south while TCE was more prevalent just
north of the southeast corner of the manufacturing building. TDEC conducted an
Expanded Site Investigation (ESI) in June 2011 to further delineate the extent of
groundwater contamination. The ESI identified two possible source areas, one located
outside a roll-up door on the west side of the manufacturing building and another located
to the south of the manufacturing building possibly attributable to the oil/water separator.
The 2011 ESI also recommended that a Hazard Ranking Score (HRS) be prepared for the
Site and that it be considered for the National Priorities List (NPL).
In December 2013, a HRS was prepared for the Walker Site (EPA, 2013), The HRS
defined two source areas including an area of contaminated soil resulting from automated
machine screw operations (unpermitted discharges and spills) and the oil/water separator
(underground tank) located about 35 ft south of the manufacturing building.
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In March 2014, the EPA contracted Black & Veatch to perform the Remedial
Investigation (RI)/Feasibility Study (FS) for the Walker Machine Site. The Site was
placed on the NPL on May 12, 2014. Black & Veatch conducted field investigations
between September 2014 and February 2017 as summarized in the RI Report (Black &
Veatch, 2018a). A FS was finalized in February 2018 (Black & Veatch, 2018b) which
evaluated remedial alternatives for cleanup of the Site.
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CERCLA Response Actions and Environmental Investigations
Date
Complete
Investigations /
Response Actions /
Report
Scope
July 2007
Walker Pre-CERCLIS
Screening Assessment
Report (TDEC, 2008)
TDEC conducted pre-CERCLIS screening of the Walker
Site including installation of monitoring wells and collection
and analyses of surface and subsurface soil, sediment,
groundwater, and waste samples from the oil/water
separator. Chlorinated VOCs (CVOCs) were detected in
groundwater, subsurface soil, and the oil/water separator
waste sample. TDOR recommended no further action at the
Site.
March 2009
Witt Site Investigation
and Site Inspection
Report (TDEC, no
date)
TDOR conducted a site investigation at the Witt property to
determine if any possible releases of contaminants from the
Witt facility posed a threat to human health and the
environment, and to assess conditions of contaminants
migrating from the Walker Machine Site. Investigation
included installation of monitoring wells and collection and
analyses of groundwater and subsurface soil. Due to CVOC
detections at the Walker Machine Site located upgradient of
Witt, TDOR recommended further investigation at the
Walker Machine Site.
2010
Walker Site
Reassessment Report
(TDEC, 2010)
TDOR conducted a site assessment including installation of
additional monitoring wells and groundwater sampling at
the Walker. Machine and Witt properties. CVOCs were
present in groundwater at both properties.
April 2011
Walker Site
Investigation Report
(TDEC, 2011)
TDOR conducted a site investigation at the Walker Site
including groundwater sampling and analyses, passive gas
soil study, and collection and analyses of confirmation soil
samples. Due to CVOC detections in soil gas and
groundwater, TDOR concluded that additional investigation
was needed at the Site.
June 2011
Walker Expanded Site
Investigation Report
(TDEC, 2012)
TDOR conducted an expanded site investigation at the
Walker Machine Site: including temporary monitoring well
installation, groundwater sampling and analyses, and
membrane interface probe (MIP) investigation. Despite
shallow refusal, the MIP identified two possible source
areas. The report recommended calculating a HRS score for
the Site and for NPL consideration.
December
2013
Walker HRS
Documentation Record
(EPA, 2013)
The EPA completed a Hazard Ranking Score (HRS) for the
Walker Machine Site. The HRS groundwater migration
pathway score was sufficient to qualify the Site for the
National Priorities List (NPL).
May 8, 2014
Walker NPL Listing
Walker Site placed on the NPL.
March 2015
Walker Vapor
Intrusion (VI) Sub-
Slab Ventilation
System Installed
The EPA conducted an emergency response action to
protect Walker building workers from vapor intrusion It
included the installation of three horizontal extraction pipes
completed approximately 1 ft below the building slab as part
of a vapor extraction system.
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CERCLA Response Actions and Environmental Investigations
Date
Complete
Investigations /
Response Actions /
Report
Scope
2015
Walker Environmental
Photographic
Interpretation Center
(EPIC) investigation
The EPA conducted an EPIC investigation, including
collection of aerial photographs showing the Walker
Machine Site in 1965, 1971, and 1980. Photos identified a
building expansion before 1971, and in 1980, an area
possibly stained by facility operations.
September
2014-May
2016
Walker RI Field
Investigations and RI
Report, Revision 0
Black & Veatch conducted Remedial Investigation (RI)
activities including collection and analysis of surface and
subsurface soil samples, installation and sampling of
monitoring wells, sampling of existing monitoring wells,
collection and analysis of surface water and sediment
samples, installation of soil vapor sampling ports and
subsequent sampling of the ports, indoor air and ambient air.
Included Human Health Risk Assessment (HHRA) and
Ecological Risk Assessment (ERA).
February
2017
Additional Walker RI
Field Investigations
and RI Report,
Revision 1
Black & Veatch conducted RI activities including collection
and analysis of surface and subsurface soil samples,
installation and sampling of one new monitoring well,
sampling of existing monitoring wells, sampling of soil
vapor sampling ports, and indoor and ambient air. Revised
the HHRA.
January 2018
RI Report, final
The RI Report, including the HHRA, were submitted as
final.
March 2018
Feasibility Study, final
The Feasibility Study was submitted as final
May 31,2018
Proposed Plan issued
The Proposed Plan was issued to the public.
3.0 Community Participation
Documents including the RI and FS Reports and the Proposed Plan for the Site were
made available to the public on May 31,2018 in the Administrative Record (AR)
repositories. The AR repositories are located at the EPA Region 4 Superfund Records
Center (61 Forsyth Street, Atlanta, GA 30303) and the Lucius E. and Elsie C. Burch
Library (501 Poplar View Parkway, Collierville, TN 38017). A Notice of Availability
was published in the Collierville Herald on May 31, 2018. A public comment period on
the Proposed Plan was held from June 8, 2018 to July 7, 2018.
On June 14,2018, the EPA hosted a Proposed Plan meeting at Lucius E. and Elsie C.
Burch Library. During the meeting the EPA presented a description of the Proposed Plan
and schedule for remedy implementation and allowed nearby residents and interested
parties to comment and ask questions of EPA officials. Four people attended the meeting;
a transcript of the meeting is included as Appendix A.
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There were some comments and questions during the public meeting and representatives
of the EPA responded during the meeting. EPA responses to written comments received
during this period are typically included in the Responsiveness Summary, which is part of
this ROD. However, no written comments were received during the public comment
period.
4.0 Scope and Role of the Response Action
This ROD presents the final Comprehensive Environmental Response, Compensation,
and Liability Act (CERCLA) remedial action at the Site. The Site has been divided into
three contaminated media zones (CMZs) including the Unsaturated Soil Zone (UZ);
Saturated Soil Zone (SSZ); and Dilute Plume (DP). All of the CMZs are being addressed
under this ROD as a single operable unit. The CMZs are shown in Figure 7.
The selected remedy will achieve the overall site goals of treating or removing soil
contamination that is a source of groundwater contamination, treating contaminants to
levels that are protective of human health and the environment and restoring
groundwater to its beneficial use as a drinking water source. These actions will also
provide a permanent solution to vapor intrusion (VI) and indoor air contamination on-
site. The selected remedy is compatible with the current and reasonably anticipated future
use of the Site. The selected remedy will be implemented in phases: (1) aggressive
remediation of contamination in the UZ (e.g., soil with high concentrations of
contaminants or NAPL); (2) phased remediation of contamination in the SSZ (e.g.,
groundwater with high concentrations of contaminants or NAPL); and (3) phased active
remediation (if necessary) of groundwater in the DP. Groundwater monitoring will be
conducted to evaluate the effects of the UZ treatment and the resulting contaminant flux
reductions before determining the timing and extent of subsequent remedial action for the
SSZ or the DP.
5.0 Site Characteristics
5.1 Conceptual Site Model
The Conceptual Site Model (CSM) incorporates information on the potential chemical
sources, affected media, release mechanisms, routes of migration, and known or potential
human and ecological receptors. It illustrates the physical, chemical, and biological
relationships between contaminant sources and affected media. An idealized CSM
depicting important features of the subsurface, sources of contamination, and aspects of
contaminant degradation and migration was developed for the Site (Figure 4). Two CSMs
were developed for the Human Health Risk Assessment (HHRA) (Figure 5) and
Ecological Risk Assessment (ERA) (Figure 6) and serve as the basis for interpretations of
contaminant fate and transport and assessments of risk to human and ecological
receptors.
The idealized CSM is not drawn to scale, but does present important relationships in the
subsurface based on the available data. The HHRA CSM illustrates that the primary
release mechanisms were spills and leaks and discharge of waste from storage and
treatment operations. Secondary release mechanisms include surface runoff and
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infiltration. Percolation of rainwater through contaminant source areas and other
contaminated subsurface soils resulted in contaminants that leached into soil. The ERA
CSM illustrates that the primary release mechanisms are runoff and leaching through
contaminated soils and discharge into drainage ditches.
5.2 Overview of the Site
5.2.1 Geologic, Hydrogeologic, and Topographic Information
The Site lies in Shelby County in western Tennessee in the Coastal Plain Physiographic
Province. This province is generally defined by broad flood plains. The region is
dominated by Cretaceous to Quaternary geologic formations consisting mainly of sands,
hard clays, silts and loess deposits.
Surface topography in the Memphis area (which includes Collierville) ranges from about
200 ft above mean sea level (amsl) on the flat alluvial plain of the Mississippi River to
about 400 ft amsl in the upland hills of eastern Shelby County. The Site is located at
about 350 ft amsl and has generally flat topography with a slight slope from northwest to
southeast; the Witt property to the west sits approximately 10 ft higher than the Walker
Machine property (TDEC, 2012).
Site drainage leaves the Site to the south as sheet flow, entering the intermittent unnamed
stream along the southern portion of the Site at about 340 ft amsl (Figure 2). This stream
flows east approximately 4-miles where it enters an unnamed tributary which continues
approximately 2 miles north to its confluence with the Wolf River (TDEC, 2012).
Western Tennessee lies in what is known as the Mississippi Embayment. This is an area
that represents a break in what was once a single, continuous mountain range comprising
the modern Appalachian range (which runs roughly on a north-south axis along the
Atlantic coast of the United States) and the Ouachita range (which runs on a rough east-
west axis west of the Mississippi River) (Van Arsdale and Cox, 2007).
The Memphis area is located near the axis of the Mississippi embayment, a regional
down-warped trough of Paleozoic rock that has been filled with more than 3,000 ft of
unconsolidated sediments (Criner and Parks, 1976). These sediments include uncemented
sand, clay, silt, chalk, gravel, and lignite. On a regional scale, the sediments form a
sequence of nearly parallel, sheet-like layers of similar lithology. The layers reflect the
trough-like shape of the Paleozoic strata. On a local scale, however, there are complex
lateral and vertical gradations in the lithology of each layer. Of interest are variations in
thickness and sand percentage of the major clay layers within the upper strata. These
confining clay units control the groundwater interchange between the sand layers that
form major aquifers. Zones where the confining clays are thin or sandy are potential sites
of high leakage, and the most likely pathways for pollutant migration (Graham and Parks,
1986). Shelby County is solely dependent on groundwater for municipal potable use.
Shelby County accounts for nearly 80 percent (%) of the groundwater withdrawals for the
state of Tennessee.
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Boring logs show that the upper 30 ft of soil under the Site is primarily composed of a
mixture of clayey and silty sand with some interbedded layers of sandy or silty clay. This
upper zone most likely represents loess deposits typical in embayment sediments. Below
the surficial deposits, the lithology is predominantly sand with some zones of interbedded
silt or clay. This sand most likely represents the Upper Memphis Sand. The boring for a
Town of Collierville well describes predominantly clay with layers of sand from 289 ft to
approximately 647 ft before transitioning to rock. This zone may represent the bottom of
the Memphis Sand near the Site.
5.3 Sampling Strategy
Multi-media sampling was guided by the CSMs that were refined as understanding of the
Site increased over time. Samples were collected and evaluated to determine the nature
and extent of soil, sediment, surface water and groundwater contamination. Soil gas' and
indoor air samples were also collected onsite to evaluate the potential for vapor intrusion.
Several rounds of sampling in selected media were performed between 2014 and 2017.
The locations of surface and subsurface soil samples were focused on known or
suspected source areas. Groundwater and limited soil gas samples were also collected
offsite. The collected data was used to evaluate potential risks, improve hydrogeologic
understanding, and evaluate potential remedy alternatives and treatment options.
5.4 Known or Suspected Sources of Contamination
In addition to the documented locations of solvent discharge, other potential contaminant
source locations have been identified based on-Site investigations. Potential contaminant
release locations are shown on Figures 2 and 4 and include:
• The former AST location and sewer drain in the rear of the building where spent
solvent was discharged, as identified during the 1987 Tennessee Department of
Labor, DOSH inspection.
• The wooded area on the property, about 115 ft south of the manufacturing building,
where a drum labeled TCE along with an unlabeled drum and drum parts were
observed during the 2011 Site investigation.
• An area of contaminated soil located outside a roll-up door on the west side of the
manufacturing building resulting from automated machine screw operations
(unpermitted discharges and spills), as defined in the 2013 HRS evaluation.
• The oil/water separator (underground tank) located about 35 ft south of the
manufacturing building, as defined in the 2013 HRS evaluation.
• A darkened area possibly stained by Site operations, in the parking area of the
facility adjacent to the southeast corner of the building, as identified in the 1980
aerial photograph.
• Beneath the southern end of the original building footprint, as identified in the 1965
aerial photograph. Contamination may have leached beneath the building slab via
potential cracks, or through in-floor building drains or drains in the covered area.
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5.5 Nature and Extent of Contamination
The extent of contamination of the chemicals of concern (COCs) identified during the RI
is summarized below for each environmental medium. Summaries of the contaminant
concentrations are shown in Tables 1 through 4.
5.5.1 NAPL Contamination
The use of cutting oil and CimCool Five Star 40 coolant was documented during an
inspection at the active Walker Machine facility (EPA, 2013). These types of cutting oil
and coolant were typically mineral oil-based petroleum hydrocarbon products. Walker
Machine Products, Inc., was also documented as using solvents (mineral spirits and 1,1,1-
TCA) in their process. Other industry typical solvents that were detected at the Site
include PCE, TCE, and carbon tetrachloride. Mineral spirits, another petroleum
hydrocarbon product, would have been light non-aqueous phase liquid (LNAPL) in pure
form. However, the chlorinated solvents would have been dense non-aqueous phase
liquid (DNAPL) in pure form.
No NAPL (LNAPL or DNAPL) was observed or directly inferred during the Site RI
investigations. The existing analytical data do not indicate the presence of pure phase
petroleum hydrocarbons in a LNAPL form, or solvent in a DNAPL form. If present at the
Site, DNAPL would be expected to exist as residual DNAPL. This supposition is based
primarily on the generally absent adsorbed concentrations and low dissolved
concentrations of chlorinated ethenes and chlorinated ethanes (e.g., 1,1,1-TCA, PCE,
TCE, and methylene chloride). However, adsorbed phase soil concentrations were not
collected directly above the second clay unit, where the highest groundwater
concentrations were detected. Soil concentration data is also limited in shallow
unsaturated soil directly beneath the Walker building. Vapor phase data indicate the
potential for a source of volatiles beneath the building. Similar to the DNAPL, LNAPL
would also be expected to exist as residual LNAPL within the vadose zone or within the
capillary fringe and water table potentiometric range. Concentrations of individual
petroleum hydrocarbon concentrations in soil and in groundwater were low or non-detect.
The lack of observable DNAPL does not preclude the presence of DNAPL as residual
that is partially fills the soil pore space.
5.5.2 Soil Contamination
The discussion of contaminant nature and extent presented in the following sections
includes a comparison of Site data to EPA Regional Screening Levels (RSLs). This data
screening is intended to provide reference points to gauge the relative magnitude of
chemicals of potential concern (COPCs). Presentation of the data in this way is not
intended to eliminate contaminants from consideration or to evaluate the risk of any
contaminant. Exceeding these levels suggests that further evaluation of the potential risk
• is necessary.
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Surface Soil
VOCs and SVOCs were not detected in surface soil. Arsenic was the only analyte that
exceeded the residential screening levels (Figure 8). Other metals exceeded screening
levels in surface soils. However, a control sample also contained screening level
exceedances of arsenic, cobalt, iron, and manganese. Metal filings from manufacturing
operations were noted in the drum area during sampling. Concentrations of metals in
surface soil were highest near the TCE drum remains and around the building; however,
metals were not analyzed in all surface soil locations.
Subsurface Soil
In subsurface soil no VOC results were in exceedance of industrial screening levels.
Diesel range organics and arsenic exceeded industrial screening levels at some locations
in soils between 1 and 6 ft bis (Figure 9).
Soil Gas
Soil gas samples were collected in 2011. PCE was detected in 23 out of 30 sample
locations and TCE in 19 out of 30 locations. The main occurrence of VOCs was around
the south side of the main plant building and towards the south property line. PCE was
more prevalent south of the building. TCE was more prevalent closer to the building; the
highest levels of TCE were noted at the at the southeast corner of the manufacturing
building (Figure 10).
5.5.3 Groundwater Contamination
In Site monitoring wells, compounds that exceeded the screening levels included: VOCs
(PCE, TCE, cis-l,2-DCE, 1,1-DCE, CT, and methylene chloride); metals (aluminum,
iron, manganese, and vanadium); and SVOCs (1,4-dioxane, bis(2-ethylhexyl)phthalate,
diesel range organics (DROs), and gasoline range organics (GROs) (Figure 10). Most of
these exceedances were limited to monitoring wells with well screen intervals above a
clay unit (-65 ft). Although this clay unit is likely discontinuous in some areas, it appears
to have reduced dissolved contamination migration deeper than the clay unit. The highest
contamination detection is located near the oil/water separator area and the AST. Other
areas of contamination include west of the Site and off-site south of the railroad tracks.
The contamination south of the railroad tracks is similar to that of onsite wells. However,
the transport mechanism of Site groundwater contamination to this area is unclear since
the predominant groundwater flow direction is to the northwest. Possible explanations for
this upgradient movement of COPCs would include; (1) DNAPL transport along low
permeable units dipping to south; (2) different historical groundwater gradients due to
nearby municipal wellfield or private well pumping; or (3) undisclosed releases in this
area.
Analytical results from 2014 indicated that benzene and PCE were present in one Town
of Collierville wellfield #1 supply well (Figure 11). The wells are sampled quarterly by
the Town of Collierville. Maximum detected concentrations of PCE and benzene in
March 2018 were 6.08 micrograms per liter (ug/1) and 0.76 ug/1, respectively. Treated
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water, before distribution, is also sampled periodically. PCE concentrations in treated
water have been below the SDWA MCL and were not detected in recent samples. The
selected remedy for this Site will greatly reduce the potential for contaminant migration
in groundwater towards the wellfield.
5.5.4 Sediment Contamination
Contaminants exceeding residential soil screening levels were detected in sediment in a
drainage ditch that receives drainage from the Witt and Walker Machine Sites, and
discharges into the intermittent stream that runs along the south site of the Site (Figure
12). The ditch is dry at times so sediment was screened against EPA RSLs for soil.
Sediment values were also compared to ecological screening values. Detected
contaminant concentrations did not exceed the ecological screening values, with the
exception of some PAHs which are likely associated with the adjacent railroad tracks.
5.5.5 Surface Water Contamination
No contaminants were detected above ambient water quality criteria or MCLs. Therefore,
there are no COPCs for surface water.
5.5.6 Subslab Vapor Phase Contamination
Subslab soil gas vapors under the Walker Machine building were sampled four times
during the RI with multiple exceedances of EPA RSLs (Figure 13). There was a decrease
of concentrations following the installation of the vapor mitigation system in March
2015. However, after the Langley business was sold in March 2016, the building was
vacant and the mitigation system was turned off. The Walker Machine property was sold
in August 2016 and the extraction system is believed to have been restarted in August
2016. There was an increase in concentrations during this time. Subslab soil gas samples
were collected again in February 2017. Concentrations were lower than the results from
samples collected in 2014.
Subslab samples were collected from the concrete apron around the Witt building in
December 2015. Exceedances of screening criteria were noted for 1,2-DCA; 1,4-dioxane;
benzene; chloroform; ethyl acetate; and styrene. The area with the highest concentrations
was adjacent to the southern end of the eastern part of the building. TCE was not
detected in these subslab samples; PCE was detected at levels less than or equal to 2.4
micrograms per cubic meter (ug/m3). The results were further evaluated by modeling the
data to determine potential indoor air concentrations. The model indicated that
contaminants in the sub-surface should not cause an unacceptable human health risk for
indoor air within the building. Samples of the air inside of the building were not collected
because the property owner did not grant access.
5.5.7 Indoor Air Contamination
Site indoor air and ambient air samples were collected four times during the RI. Several
VOC compounds exceeded residential EPA RSLs (Figure 14). Early results triggered the
EPA to conduct an emergency response action in March 2015 to mitigate the impact of
the contaminants on site workers. Following installation and operation of the vapor
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mitigation system there was a decrease in VOC concentrations, including TCE and PCE.
Indoor air concentrations were well below removal management levels during the
sampling performed during 2017.
6.0 Current and Potential Future Land and Groundwater Uses
6.1 Land Uses
The facility is zoned General Industry (Collierville, 2016) and the Site is currently used
for industrial/commercial purposes. Land use immediately surrounding the Walker
property is general industry with medium to high residential zoning north and south of
the Site. 901 Customs currently owns the property and is operating a vehicle
customization business at the Site. Reasonably anticipated future land use of the Site
property is anticipated to continue to be industrial/commercial. The Town of Collierville
has projected that future use of the Site property and adjacent parcels will be for
"technology employment centers."
6.2 Ground and Surface Water Uses
Groundwater in the Memphis Sand is an EPA Class II, Subclass IIA, Current Source of
Drinking water and beneficial use per Guidelines for Ground-Water Classification Under
the EPA Ground-Water Protection Strategy. Subclass IIA groundwater is categorized as
groundwater that is currently being used or is potentially available for drinking water
regardless of its vulnerability. Class II groundwaters generally receive a very high level
of protection.
Groundwater in the Collierville area is currently used as a source of drinking water and
will continue to be used for drinking water in the future. There are no known private
drinking water wells at the Site or in within the extent of the groundwater contamination
associated with the Site. The Town Collierville operates several water plants that obtain
their water from the Memphis Sands aquifer. Town of Collierville Wellfield #1 is the
closest wellfield to the Site. PCE was detected in one supply well at a concentration of
6.08 ug/1, which is above the SWDA MCL of 5 ug/1, during the most recent sampling.
However, PCE concentrations in treated water have been below the SDWA MCL and
were not detected in recent samples. The selected remedy for this Site will greatly reduce
the potential for contaminant migration towards Collierville's Wellfield #1. It may take
about 20 years to achieve groundwater cleanup levels.
An intermittent unnamed stream runs along the southern property boundary of the Site.
Site drainage leaves the Site as sheet flow entering the stream. The stream flows east
approximately 4 miles where it enters an unnamed tributary of the Wolf River. The
unnamed tributary flows approximately 2 miles north to its confluence with the Wolf
River. There is a ditch located southwest of the Walker building and southeast of the Witt
building that also discharges into the intermittent unnamed stream. The onsite overflow
pond will fill and hold rain water following large rainfall events. Historically, the
overflow pond could drain to the unnamed stream; however, the outlet is currently
overgrown and does not appear functioning.
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7.0 Summary of Site Risks
A site-specific baseline risk assessment was conducted to estimate the current and future
effects of contaminants on human health and the environment. A baseline risk assessment
is an analysis of the potential adverse human health and ecological effects of releases of
hazardous substances from a site in the absence of any actions or controls to mitigate
such releases, under current and future land uses. The baseline risk assessment includes a
baseline HHRA and a baseline ERA. The results of the HHRA are provided in the
September 2018 baseline human health risk assessment. The results of the ERA are
provided in the screening level ecological risk assessment.
7.1 Summary of the Human Health Risk Assessment
A four-step human health risk assessment process was used for assessing site-related
cancer risks and non-cancer health hazards. The four-step process is summarized in the
following subsections.
7.1.1 Hazard Identification (Identification of Chemicals of Concern)
In this step, the COCs at the Site in the various media (e.g., groundwater, soil, sediment,
surface water, soil gas and indoor air) are identified based on factors such as toxicity,
frequency of occurrence, fate and transport of the contaminants in the environment,
concentration of the contaminants in specific media, mobility, persistence, and potential
for bioaccumulation. Screening was conducted in accordance with EPA Region 4 Human
Health Risk Assessment Supplemental Guidance.
The COPCs in subsurface soil, groundwater, sediment and indoor air at the Site are listed
in Tables 1 through Table 4, respectively. The COCs were further refined and are listed
in tables 21-23. There are no COCs identified for surface water as contaminants were
below AWQC screening criteria. Benzo(a)pyrene TEQ and arsenic were identified as
COCs in sediment. However, the benzo(a)pyrene TEQ is possibly associated with the
nearby railroad track. Arsenic appears to be naturally occurring. These two contaminants
do not appear to be site related.
7.1.2 Exposure Assessment
In this step, the different exposure pathways through which people might be exposed to
the COCs in the various media identified in the previous step are identified. Examples of
exposure pathways include incidental ingestion and dermal contact with contaminated
groundwater. Factors relating to the exposure assessment include, but are not limited to,
the concentrations in specific media that people might be exposed to and the frequency
and duration of the exposure. Using these factors, a reasonably maximum exposure
scenario is calculated, which is an appropriate mix of values that reflect averages (for
example, adult body weight) and 95th percentile distributions that together portray the
highest level of human exposure that could reasonably be expected to occur.
Based on an understanding of the fate and transport properties of the contaminants, and
the potential for human contact with the affected media, the receptors evaluated included
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residents, trespassers, industrial/commercial workers, and construction workers. Figure 5
presents the CSM developed for the HHRA.
Potentially complete exposure pathways examined for soil, groundwater, sediment and
indoor air were:
• Ingestion of soil/groundwater/sediment.
• Dermal contact with soil/groundwater/sediment.
• Inhalation of dusts from soil/vapors from groundwater.
• Inhalation of indoor air from subsurface vapor intrusion.
The exposure point concentrations (EPCs) for the COCs in each media were calculated in
accordance with EPA Region 4 Human Health Risk Assessment Supplemental Guidance
and are shown in Tables 1 through 4.
Human intakes were calculated for each COC and receptor using the EPCs. Estimates of
human intake, expressed in terms of mass of chemical per unit body weight per time
(mg/kg/day), were calculated differently depending on whether the COC is a non-
carcinogen or a carcinogen. For non-carcinogens, intake was averaged over the duration
of exposure and is referred to as the average daily dose (ADD). For carcinogens, intake
was averaged over the average lifespan of a person (70 years) and is referred to as the
lifetime average daily dose (LADD).
7.1.3 Toxicity Assessment
EPA toxicity assessments and the resultant toxicity values were used in the HHRA to
determine both carcinogenic and non-carcinogenic risks associated with each COC and
route of exposure. EPA toxicity values that were used in the 2017 HHRA were:
• Chronic and sub-chronic Reference Dose (RfD) and Reference Concentration (RfC)
values for non-carcinogenic effects, and
• Oral Cancer Slope Factors (CSFs) and Inhalation Unit Risk (IUR) values for
carcinogenic effects.
7.1.4 Risk Characterization
Risk characterization integrates the results of the exposure and toxicity assessments to
estimate potential non-cancer hazards and cancer risks. The EPA uses a Hazard Index
(HI) approach to characterize the overall potential for non-carcinogenic effects associated
with exposure to multiple chemicals. This approach assumes that simultaneous sub-
threshold chronic exposures to multiple chemicals that affect the same target organ are
additive and could result in an adverse health effect. The HI is calculated as follows:
HI = ADD1 /RfDl + ADD2 /RfD2 +ADDi /RfDi
where:
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ADDi = Average Daily Dose for the ith toxicant
RfDi = RfD for the ith toxicant
The term ADDi/RfDi is referred to as the hazard quotient (HQ).
Calculation of an HI in excess of a HI=1 indicates the potential for adverse health effects.
Indices greater than one are generated when intake for any of the COCs exceeds its RfD
or RfC. However, given a sufficient number of chemicals under consideration, it is also
possible to generate a total HI greater than one even if none of the individual chemical
intakes exceeds its respective RfD or RfC. The potential for cumulative non-cancer
effects for multiple COCs and multiple exposure media was evaluated.
Carcinogenic risk is expressed as a probability of developing cancer as a result of lifetime
exposure. Excess lifetime cancer risk for a given chemical and route of exposure is
calculated as follows:
Risk = LADD x CSF
These risks are probabilities that are generally expressed in scientific notation (e.g., 1 x
10-6 or 1E-06). An incremental lifetime cancer risk (ILCR) of 1E-06 indicates that, as a
plausible upper-bound, an individual has a one-in-one-million chance of developing
cancer as a result of site-related exposure to a carcinogen over a 70-year lifetime under
the specific exposure conditions at the Site. For exposures to multiple carcinogens, the
EPA assumes that the risk associated with multiple exposures is equivalent to the sum of
their individual risks. Increased cancer risks less than 1E-06 indicate no action is
required. Cancer risks between 1E-06 and 1E-04 generally do not warrant cleanup unless
dictated by site-specific circumstances or other considerations. Increased cancer risks
greater than 1E-04 indicate some type of action needs to be considered.
Tables 5 through 20 present a summary of the unacceptable cancer risks and non-cancer
hazards identified in the HHRA associated with exposure to the COCs in soil,
groundwater, sediment, and indoor air.
Risks from Exposure to Soil
As presented in Table 5, the excess cancer risk calculated for future residents exposed to
the COCs in on-site surface soil was 1.3E-05. The excess cancer risks calculated for
future construction workers (Table 7) exposed to combined on-site surface and
subsurface soil was 2E-06. As presented in Table 6, non-caricer hazard indices for all
exposures to soil were below 1 for the future resident exposed to on-site surface soil (HI
= 0.3). However, as presented in Table 8, non-cancer hazard indices greater than one
were calculated for the future construction worker exposed to combined on-site surface
and subsurface soil (HI =11). The HI for the future construction worker based on
exposure to soil is primarily associated with manganese. However, nearly all surface and
subsurface soil samples from the RI showed concentrations similar to these reported
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naturally occurring concentrations. One surface soil sample at the Site had a
concentration of 1600 ppm. Manganese is ubiquitous in soil; the Tennessee Division of
Superfiind has estimated that the average naturally occurring concentration in Tennessee
is about 930 ppm. Based on these reported naturally occurring concentrations and similar
site-specific background levels, manganese is not considered to be a COC and surface
soil is not considered to be impacted by metals.
The COCs in the subsurface soils are CVOCs (PCE, TCE, cis-l,2-DCE, and 1,1-DCE).
Risks from Exposure to Groundwater
As presented in Table 9, excess cancer risks exceeding 1E-04 were calculated for future
residents exposed to the COCs in on-site and off-site groundwater (4E-04 and 2E-04,
respectively). Excess cancer risks for industrial workers and construction workers were
below 1E-04 (Tables 11 and 13, respectively). As presented in Table 10, non-cancer
hazard indices greater than one were calculated for the future resident hypothetically
exposed to on-site and off-site groundwater (His = 51 and 29, respectively). Non-cancer
hazard indices greater than 1 were also calculated for the future industrial worker
exposed to on-site and off-site groundwater (His = 6 and 2, respectively as presented in
Table 12). In addition, as presented in Table 14, a non-cancer HI greater than one was
also calculated for the future construction worker exposed to on-site groundwater (HI =
5). The calculated HI was below 1 for exposure to off-site groundwater for future
construction workers. Direct exposure to contaminated groundwater is not currently
occurring on- or off-site because there are no known private drinking water wells onsite
or within the area of the contaminated groundwater. Treated drinking water at the nearby
Town of Collierville Wellfield #1 continues to meet federal MCLs.
The COCs in groundwater include chlorinated ethenes (PCE, TCE, 1,1-DCE, cis-1,2-
DCE, VC), chlorinated ethanes (1,1-DCA), and 1,4-dioxane.
Risks from Exposure to Sediment
As presented in Table 15, the excess cancer risk calculated for future residents exposed to
the COCs in on-site sediment was 4E-06. Although the cancer risk estimates for sediment
are below 1E-04, they contribute to an overall excess cancer risk exceeding 1E-04 for
future residents. As presented in Table 16, non-cancer hazard indices for all exposures to
sediment were below 1 for the future resident exposed to on-site sediment.
Risks from Exposure to Indoor Air
As presented in Table 17, excess cancer risks exceeding 1E-04 were calculated for future
residents exposed to the COCs in on-site indoor air (2E-04). The excess cancer risk
calculated for future residents exposed to the COCs in off-site indoor air and for
current/future industrial workers exposed to both on-site and off-site indoor air were
below 1E-04 (Tables 17 and 19, respectively). As presented in Tables 18 and 20, non-
cancer hazard indices greater than 1 were calculated for the future resident and
current/future industrial worker exposed to on-site indoor air (His = 39 and 9,
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respectively). The calculated His were below 1 for all exposures to off-site indoor air for
the future resident and current/future industrial worker.
The COCs for indoor air include chlorinated ethenes (PCE, TCE) and petroleum
hydrocarbons (1,2,4-trimethlybenzene, naphthalene, total xylenes).
7.1.5 Uncertainties
The calculations presented in this HHRA are meant to assist the EPA remedial project
manager with information on which to base risk management decisions. A combination
of site-specific exposure information, standard default assumptions, and professional
judgment were used to select exposure units and develop exposure assumptions for the
various receptors evaluated in the HHRA. These exposure assumptions are conservative
and are likely to overestimate hazards and risks.
7.1.6 HHRA Conclusion
The intent of the HHRA is to evaluate the potential risks to human health due to releases
of chemicals and exposure to contaminants at the Walker Machine Site. The main
objective of the HHRA is to determine unacceptable risks associated with the Site,
whether action under CERCLA is warranted and develop cleanup levels that are
protective. Cancer risks are considered unacceptable if the total cancer risk exceeds 1E-
04, and non-cancer hazards are considered unacceptable if the total HI exceeds 1. The
results of the HHRA for the Walker Machine Site indicate that residential exposures
result in unacceptable cancer risks and non-cancer - hazards, current and reasonably
anticipated future of the site is industrial/commercial. Industrial/commercial worker and
construction worker exposures result in unacceptable non-cancer hazards (see the chart
below). The potential for exposure to unmitigated future indoor air concentrations and the
potential ingestion of contaminated groundwater are the primary risk drivers. Current
exposure to indoor air in the Walker Building is being addressed through a subslab vent
system that was installed in 2015.
The response action selected in this ROD is necessary to protect public health and the
environment from actual or threatened releases of hazardous substances, contamination
and pollutants into the environment. Therefore, action under CERCLA is warranted.
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RISK SUMMARY FOR PATHWAYS WITH UNACCEPTABLE RISK
Receptor
Pathway
Noncarcinogenic
Risk
(Hazard Index)
Carcinogenic Risk
Onsite
Future Industrial
Worker
Inhalation of indoor
air, ingestion of
groundwater
15 a
Future Resident
Inhalation of indoor
air,
Ingestion, dermal
contact, inhalation
of groundwater
91
6x10-4
Future Construction
Worker
Ingestion of
groundwater,
inhalation, dermal
contact, ingestion
of subsurface soil
17 (5) b
Offsite
Future Resident
Ingestion, dermal
contact, inhalation
of groundwater
29
2x10-4
Notes:
a: assumes that current existing subslab system to address vapor intrusion is no longer
working
b: HI=17 if include exposure to likely naturally occurring metals, primarily manganese.
HI=5 omits risk calculated for likely naturally occurring metals in soil including
manganese.
7.2 Summary of the Ecological Risk Assessment
A screening level ERA for the Walker Machine Site was completed as part of the RI. The
ERA evaluated data collected from 2007-2015. The EPA ERA evaluated potential risks
to aquatic organisms in the on-site creek and to sensitive terrestrial organisms (mammals
and birds), in and around the Site. Figure 6 presents the CSM developed for the ERA.
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7.2.1 Risks Estimates to Aquatic Organisms
No chemicals of potential ecological concern (COPECs) were identified in surface water,
so aquatic organisms are not at risk from this medium. Only PAHs in sediment were
identified as COPECs. PAH toxicity to benthic organisms was evaluated by comparing
literature-based probable effects concentration (PEC) for total PAHs and using site-
specific data in an equilibrium partitioning sediment benchmark (ESB) model developed
by the EPA (EPA, 2003). The conservative ESB model pertains only to exposure to
sediment pore water concentrations, not to surface water. The results do not suggest
chronic narcotic toxicity to benthic organisms based on equilibrium concepts between the
PAHs in sediment and their predicted pore water effect concentrations.
The greatest uncertainty in using the ESB approach for the Site is that the stream does not
flow for much of the year and the equilibrium portioning methodology only applies to
permanently inundated sediments. Therefore, the results are considered overly
conservative to most benthic aquatic invertebrates that may temporarily dwell in stream
sediment.
The substrate habitat in the stream is comprised mainly of eroded soils from the
headwater area. Severe erosion occurs between the Walker Machine and Witt properties
and between the railroad and the Witt parking lot. The stream substrate changes
depending on the severity of runoff events and deposits of new soil/sediment.
The PAHs do not appear to originate from the Site since none of the samples had elevated
concentrations to be of concern. The upstream reference sediment sample contained
PAHs that were comparable to two of the downstream stations. It is likely that the PAHs
originated from off-site runoff of the railroad and parking lots west of the Site.
7.2.2 Risk Estimates to Terrestrial Organisms
The concentrations of metal COEPCs in the abandoned drum area and overflow
impoundment are highly isolated in very small "hot spots." Potential adverse risks may
occur to receptors within the affected area. However, local populations of insectivorous
mammals and birds that may reside with the overall habitat area of the Site and adjacent
environment are not likely to be adversely affected.
7.2.3 Uncertainties
The assessment of risks to benthic organisms in the intermittent stream is considered an
overestimation because the assessment relied heavily on very conservative screening-
level benchmarks to evaluate potential exposures and effects to benthic organisms.
The affected soil area represents only a tiny fraction of local habitat structure and
function and constitutes a very small fraction of the home range of potential receptors.
Elevated levels of metals in the abandoned drum area are not anticipated to pose
significant adverse risk to local populations of wildlife.
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7.2.4 ERA Conclusion
The ERA concluded that potential risks to both aquatic and terrestrial receptors are
negligible. The evaluation of potential risks to aquatic organisms in the unnamed
intermittent stream suggests potential risk to benthic organisms from PAHs. However,
the sources of the PAHs do not appear to be related to the Site. Potential risks to
terrestrial receptors are limited to a small fraction of the home range of local populations
of wildlife and are not expected to pose any significant adverse risks.
8.0 Remedial Action Objectives
Remedial action objectives (RAOs) are identified following completion of the baseline
risk assessment and describe what the proposed cleanup is expected to accomplish. These
objectives are based on available information and standards, such as applicable or
relevant and appropriate requirements (ARARs), to-be-considered guidance, and Site-
specific risk-based levels, if applicable. RAOs for the Site are based on the protection of
groundwater which is used a source of drinking water and also consider the current use
and reasonably anticipated future use of the Site as industrial/commercial property. RAOs
address the contaminants and media of concern, the exposure route(s) and receptor(s),
and the acceptable contaminant levels or range of levels for each exposure route.
The following RAOs were developed for the Walker Machine :
• Prevent and/or. minimize the COC contaminated groundwater plume from
expanding within the Memphis Sand aquifer;
• Restore groundwater quality within the extent of the contaminant plume to meet
drinking water standards (MCLs) as a potential drinking water source;
• Prevent and/or minimize COC migration from soil and groundwater to indoor air
for the protection of current and reasonably anticipated future land use;
• Maximize the mass removal or destruction of any potential residual NAPL and
adsorbed-phase COCs from the UZ and SSZ media zones that can be a source of
leachate or a source of volatile vapors that may migrate into the Walker Building;
• Reduce or eliminate the long-term teachability of CVOCs in soil into the
groundwater by meeting Site- specific soil leachability cleanup levels for
subsurface soils;
• Prevent human exposure to Site-related contaminated groundwater at
concentrations above SWDA MCLs, or that pose an unacceptable risk where MCLs
have not been established;
• Prevent human exposure to Site-related contaminated indoor air at concentrations
that pose an unacceptable risk.
The general remedial strategy at the Site is driven by the need to restore and protect the
drinking water resource that exists under the Site and to protect future Site occupants
from inhalation of Site-related contaminant vapors in indoor air. The remedial strategy
for the Site can be described as follows: (1) aggressive remediation of contamination in
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the UZ (e.g., soil with high concentrations of contaminants or NAPL); (2) phased
remediation of contamination in the SSZ (e.g., groundwater with high concentrations of
contaminants or NAPL); and (3) phased active remediation (if necessary) of groundwater
in the DP. The flux reduction of COCs from the UZ and SSZ would be evaluated before
implementation of DP remediation.
8.1 Cleanup Levels
The cleanup levels were derived for the Site with consideration of risk to human health
and the environment and to specific chemical-based ARARs for the COCs and distinct
media. The cleanup levels for subsurface soil, groundwater and indoor are presented in
Tables 21-23. Contaminants in sediment and surface water do not require action. Contact
with site related contaminants in surface soil does not pose an unacceptable risk.
However, the cleanup of soil is necessary to reduce the source of contaminants leaching
from soil to groundwater. The cleanup of soil will also reduce the potential for future
vapor intrusion into the main building at the Site.
The cleanup levels for CVOCs in subsurface soil are based on the protection of
groundwater. The cleanup levels were calculated for the migration to groundwater using
the soil/water partitioning equation (EPA, 1996) and a dilution/attenuation factor of 20.
The cleanup levels for groundwater are based on the SWDA MCLs or a 10"6 risk level in
the absence of MCLs. One exception is for 1,4-dioxane. The cleanup level has been set at
the current EPA contract required detection limit of 2 ug/1 which corresponds to a risk
level of 2.9 xlO"6. The cleanup levels for indoor air are based on site-specific risk based
levels that are protective of onsite industrial receptors based on a HQ=1.
9.0 Description of Alternatives
To develop and focus the remedial alternative evaluation process in the FS, the Site was
segregated into three separate areas called CMZs. CMZs are defined by one or more of
the following characteristics; lithology, COCs, depth, areal extent, and/or presence of
DNAPL. The three CMZs at the Site are the UZ, SSZ, and DP. Figure 7 depicts the
CMZs. A summary of the remedial alternatives retained for evaluation for each CMZ is
presented in this section. A detailed screening and comparative analysis of the potential
remedy alternatives is included in the Feasibility Study Report.
9.1 Description of the Unsaturated Soil Zone (UZ) Remedy Alternatives
The UZ represents on-site unsaturated soil between approximately 0 and 50 ft bis
impacted with CVOC contamination and petroleum hydrocarbon contamination
(including SVOCs and VOCs) above levels that may cause unacceptable levels of vapor
intrusion into indoor air in the on-site building. The UZ also represents unsaturated soil
impacted with CVOC contamination that may leach into groundwater. The areal extent
for this zone is conservatively estimated based on historical Site information and
potential transport mechanisms. It encompasses the Walker building, the vicinity of
buried oil/water separator, former AST and pond, TCE drum location, and south to
intermittent stream. The lithology of this zone is a mixture of clayey and silty sand with
interbedded layers of sandy/silty clay to approximately 30 ft bis. Below 30 ft bis,
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lithology is predominantly sand with zones of interbedded silt/clay. The five remedial
alternatives developed for the UZ are:
9.1.1 UZ Alternative 1: No Action
Estimated Capital Costs: $0
Estimated Annual Operation and Maintenance (O&M) Costs: $40,000
Estimated Present Worth Costs: $40,000
Estimated Time to Achieve RAO/Cleanup Levels: N/A
Section 300.430(e)(6) of the NCP directs that a "No Action Alternative" be evaluated to
provide a baseline scenario to compare against all other alternatives against. The No
Action Alternative can include compliance monitoring. In general, the alternative is
applicable when there is no current or potential threat to human health and the
environment or when CERCLA exclusions preclude taking an action. Under No Action
Alternatives, no funds are expended for control or remediation of the contaminated
media. Funds are required for the statutory Five-Year Reviews (FYRs) of the Site for site
visits, minimal compliance sampling and analyses of select contaminated media, review
of regulatory changes, and report preparation.
The UZ would remain in its present condition. Minimal periodic sampling and analysis of
COCs in groundwater and soil (for VI monitoring) would be used to track contaminant
concentrations over the course of a 30-year monitoring period.
9.1.2 UZ Alternative 2a: Soil Vapor Extraction (SVE) with Limited Air Sparging
Estimated Capital Costs: $2,001,999
Estimated Annual O&M Costs: $976,135
Estimated Present Worth Costs: $2,978,100
Estimated Time to Achieve RAOs/Cleanup Levels: ~5 yrs
Alternative UZ #2a consists primarily of SVE as a prescribed remedy for treatment of UZ
soil, with air sparging being implemented in a limited area to address the highest
concentrations of groundwater contaminants that are present in the vicinity of the
oil/water separator. A sparge pilot may be conducted to validate the use of this
technology at the Site. SVE will also be implemented under the building to reduce VI
into the building.
This alternative includes the installation of ten, 4-inch diameter permanent angled SVE
wells installed beneath the Walker building and forty-three, 4-inch diameter permanent
vertical SVE wells screened from 5 to 50 ft bis with an average 20-ft SVE radius of
influence. Installation of six permanent vapor monitoring points is assumed for collecting
chemical and vacuum readings.
Forty-four, 2-inch permanent air sparge wells would be installed within an area
approximated by the SSZ. The air sparge wells are assumed to have 3-ft screens and
would be screened below the water table, midway between the top of the second clay unit
and the top of the water table (conservatively approximated as 69 to 72 ft bis).
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Alternative UZ #2a also includes installation of two 2-inch diameter 260-ft long
horizontal utility bored vapor recovery wells approximately 5 to 10 ft bis as an added
protection from VI into the building. The remedy will treat approximately 104,800 bey of
CVOC and petroleum hydrocarbon-contaminated soil located throughout the UZ.
Additionally, the air sparge component will enhance volatilization of COCs from the
upper horizon of the SSZ. Equipment includes a trailer-mounted SVE system (with
extraction blower, air/fluid separation [knockout tank], and vapor phase carbon), and a
trailer-mounted air sparge system (with air compressor and other appurtenances). A
manifold extraction and air injection system would allow phased operation of the SVE
and sparge systems, allowing 8 to 10 points being operated at any given time. Sequencing
of SVE well operation may also be used to allow their use as air entry wells.
Finally, this alternative includes some targeted excavation near the southeast corner of
the building, the oil water separator, and the drum area, as necessary.
9.1.3 UZ Alternative 2b: Thermally Enhanced SVE with Limited Air Sparging
Estimated Capital Costs: $5,285,201
Estimated Annual O&M Costs: $976,135
Estimated Present Worth Costs: $6,261,300
Estimated Time to Achieve RAOs/Cleanup Levels: ~5 yrs
Alternative UZ #2b is similar to UZ#2a except that it adds a thermal enhancement to the
planned SVE (TE-SVE) that would be implemented in a limited area to enhance
contaminant removal in the suspected source areas. SVE will also be implemented under
the building to reduce VI into the building. This alternative includes the installation of
ten, 4-inch diameter permanent angled SVE wells installed beneath the Walker building
and 43, 4-inch diameter permanent vertical SVE wells screened from 5 to 50 ft bis with
an average 20-ft SVE radius of influence. Installation of six permanent vapor monitoring
points is assumed for collecting chemical and vacuum readings.
The area assumed for thermal enhancement and air sparging is approximated by the areal
extent of the SSZ. In addition to the vapor recovery wells, TE-SVE includes installation
of sixty-three heater borings with an average 25-ft spacing to heat unsaturated soil from 5
to 55 ft bis, six temperature monitoring points, and TCH equipment including power
supply, power distribution system, and other ancillary equipment. A target temperature of
approximately 160°F is specified to promote enhanced volatilization and desorption.
Well materials and conveyance piping within the SSZ area will be selected to operate at
the higher temperature.
The ancillary air sparge system will be installed as per UZ Alternative #2a. A sparge pilot
may be conducted to validate the use of this technology at the Site. This alternative also
includes targeted soil excavation (about 900 cubic yards) near the oil/water separator, the
drum area, and near SE corner of building. Composite soil sampling of excavated soils
will be used to confirm soil disposition and classification. Contaminated soils are
expected to meet Resource Conservation and Recovery Act (RCRA) land disposal
standards and Subtitle D requirements. Any soils exceeding the Subtitle D Landfill
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requirements or exceeding a characteristic waste threshold will be segregated for disposal
at a RCRA Subtitle C hazardous landfill. Clean fill will be used to backfill the
excavation.
9.1.4 UZ Alternative 3: Limited Soil Excavation with SVE
Estimated Capital Costs: $2,722,209
Estimated Annual O&M Costs: $738,963
Estimated Present Worth Costs: $3,461,200
Estimated Time to Achieve RAOs/Cleanup Levels: ~5 yrs
Alternative UZ #3 consists of limited soil excavation combined with SVE to remove or
treat a total of approximately 104,800 bey of contaminated soil. Approximately 10,700
bey of soil would be excavated to a depth of approximately 20 ft bis to remove the bulk
of CVOC-contaminated soil south of the Walker building, in an area that was most likely
a CVOC discharge area. Soil excavation may require the use of side-wall shoring or other
precautions to protect the building structure. Excavated soil would be sampled for waste
profiling, segregated if necessary, and loaded on trucks for off-facility disposal.
Approximately 60 % of the excavated soils were assumed to require disposal. The
remaining 40 % of soils are estimated to not exceed cleanup levels. Composite soil
sampling of excavated soils will be used to confirm soil disposition and classification.
Contaminated soils are expected to meet RCRA land disposal standards and Subtitle D
requirements. Any soils exceeding the Subtitle D Landfill requirements or exceeding a
characteristic waste threshold will be segregated for disposal at a RCRA Subtitle C
hazardous landfill. Clean fill will be used to backfill the excavation..
Four high density polyethylene (HDPE) laterals would be placed at the bottom of the
excavation as a contingency for the future application of treatment amendments below
the excavated area. The laterals would then be covered with clean sand and liner prior to
placement of clean compacted fill.
Soil excavation is expected to remove the most highly contaminated soils, but is limited
to a portion of the UZ volume. The remaining UZ contamination, including
contamination beneath the building, would be addressed with SVE as described for
Alternative UZ #2a. SVE will also eliminate VI into the building. This alternative also
includes the installation of 53 permanent 4-inch SVE wells (10 angled and 43 vertical) in
the same locations as for UZ #2a. Forty of the wells would be screened from 5 to 50 ft
bis, and 11 would be screened from 20 to 50 ft bis under the area of soil excavation. The
number of SVE wells is based upon an average 20-ft SVE radius of influence. The SVE
component is designed to treat approximately 94,100 bey of CVOC and petroleum
hydrocarbon-contaminated soil located throughout the UZ. A contingency has been
included for six 2-inch diameter air entry wells screened from 5 to 50 ft bis to facilitate
more uniform subsurface airflow. The proposed SVE equipment and operation matches
the UZ #2a configuration.
9.1.5 UZ Alternative 4: In-situ Chemical Oxidation (ISCO) and SVE
Estimated Capital Costs: $2,627,391
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Estimated Annual O&M Costs: $738,963
Estimated Present Worth Costs: $3,366,400
Estimated Time to Achieve RAOs/Cleanup Levels: ~5 yrs
Alternative UZ #4 consists of two remedy .components: a density-driven ISCO flood
using shallow laterals in the southern portion of UZ, and SVE over the remaining UZ.
Overall, the remedy will treat approximately 104,800 bey of CVOC-contaminated soil.
ISCO, presumably with KMn04, would be used to target all UZ soils south of the
building over an area of approximately 33,000 square feet (ft2). The SVE system would
be used to remediate CVOC contamination beneath the building and to prevent VI.
A density driven flood will allow the permanganate to infiltrate through the UZ in a
manner like the presumed PCE release, as both chemicals have equivalent specific
gravities. Thus, an ISCO flood would be expected to flow vertically from its point of
origin, following preferential lateral and vertical pathways down to and into the water
table. Any natural oxidant demand (NOD) or COCs would be treated en route and the
oxidant could be expected to be partially retained in the soil, particularly in lower
permeability zones, as a residual fluid for treatment of desorbing COCs. The ISCO flood
would be applied through nine (9) 150-ft infiltration laterals installed at 4 ft bis. A semi-
permeable membrane would be installed beneath the laterals to generate a more uniform
sheet flow across the treatment area. The ISCO laterals would then be covered with clean
sand and liner prior to placement of clean compacted soil. The liner would minimize rain
and stormwater infiltration from flushing the ISCO treatment area. The dosing and timing
of periodic oxidant additions would be designed to match infiltration rates and prevent
undue loss of oxidant into the saturated zone.
The SVE component will include the installation of 23 permanent 4-inch diameter SVE .
wells (7 angled and 16 vertical) with screened intervals from 5 to 50 ft bis. The number
of SVE wells is based upon an average 20-ft SVE radius of influence. The SVE
component is designed to treat approximately 30,500 bey of CVOC and petroleum
hydrocarbon-contaminated soil located throughout the UZ. A contingency has been
included for six 2-inch diameter air entry wells screened from 5 to 50 ft bis to facilitate
more uniform subsurface airflow. The proposed SVE equipment and operation matches
the UZ #2a configuration.
9.2 Description of the SSZ Remedy Alternatives
The SSZ represents saturated soil beneath suspected source areas at depths between
approximately 50 and 75 ft bis. This zone conservatively encompasses the vicinity of the
former AST (where discharge was observed), the TCE drums, and the oil/water separator
where the highest levels of groundwater contamination were detected. It also includes the
area underneath the southern portion of the Walker building (near the southern end of
original building footprint), where the highest subslab vapor concentrations were
measured. The lithology of this zone is predominantly sand with zones of interbedded
silt/clay.
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The SSZ is impacted with CVOCs in groundwater above MCLs, ranging from
approximately 1,500 to 2,600 jag/L total VOCs. The highest concentration of CVOCs
measured in soil in this zone was 185 micrograms per kilogram (ng/kg) total VOCs. This
CMZ was configured to represent the area with highest concentrations of groundwater
contamination and potential adsorbed or residual source material contributing to
dissolved contamination. Remediation of this zone is focused on protection of humans
from continued migration and dissolution of adsorbed CVOCs, and possible residual
DNAPL, into groundwater. The five remedial alternatives developed for the SSZ are:
9.2.1 SSZ Alternative 1: No Action
Estimated Capital Costs: $0
Estimated Annual O&M Costs: $40,000
Estimated Present Worth Costs: $40,000
Estimated Time to Achieve RAOs/Cleanup Levels: N/A
This remedy is analogous to the No Action Alternative UZ #1. Minimal periodic
sampling and analysis of COCs in groundwater would be used to track contaminant
concentrations over the.course of a 30-year monitoring period.
9.2.2 SSZ Alternative 2: Groundwater Recovery and Treatment/Hydraulic
Containment
Estimated Capital Costs: $479,959
Estimated Annual O&M Costs: $1,132,680
Estimated Present Worth Costs: $1,612,600
Estimated Time to Achieve RAOs/Cleanup Levels: 20 yrs
Alternative SSZ #2 consists of recovery and treatment of CVOC-contaminated
groundwater to provide long-term COC mass removal and hydraulic containment.
Recovered groundwater is treated via air stripping and activated carbon, and the effluent
is routed to an on-site infiltration gallery. Three 4-inch diameter recovery wells screened
from 50 to 75 ft bis are configured for groundwater recovery. The recovered groundwater
is treated via a trailer-mounted air stripping treatment system consisting of a tray air
stripper, bag filter assembly, discharge pump, and granular activated carbon (GAC) units.
The water would be discharged back into the aquifer via a 3,000-ft2 by 3-ft deep
infiltration gallery. Injection wells could be used in lieu of an infiltration gallery but
would nominally require twice the screen interval of the recovery wells. Preliminary
calculations indicate that an extraction rate of 15 gallons per minute (gpm) per well will
produce a downgradient capture distance of 75-feet. This flowrate is tenable without
excessive drawdown, induced at the extraction wells. The formation may be capable of
yielding higher flowrates of approximately 25 gpm. The three wells can provide full areal
coverage of the SSZ with the addition of capturing the lateral extent and upgradient
extent of the entire dissolved plume located on-site. Confirmation of the aquifer hydraulic
conductivity and soil infiltration rate are critical data gaps for this alternative.
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9.2.3 SSZ Alternative 3: ISCO
Estimated Capital Costs: $4,446,211
Estimated Annual O&M Costs: $82,934
Estimated Present Worth Costs: $4,529,100
Estimated Time to Achieve RAOs/Cleanup Levels: 5 yrs
Alternative SSZ #3 involves a dense array, full coverage injection of a chemical oxidant
such as persulfate or permanganate to oxidize residual DNAPL, CVOCs adsorbed on
saturated soil, and CVOCs dissolved in groundwater. For the purposes of estimating the
cost of this alternative, KMn04 was assumed as the oxidant. Organic compounds in
contact with the chemical oxidant would be quickly destroyed; thereby eliminating
contaminant mass available for dissolution and lateral solvent transport. Effective
implementation of ISCO is dependent upon uniform oxidant distribution and contact with
contaminants. The persistence of the oxidant will allow secondary contact with advecting
COCs as well as providing diffusion into low permeable units over time to minimize back
diffusion of COCs.
This alternative would include installing fifty-two (52) 2-inch diameter well clusters (12
angled clusters and 40 vertical clusters) for ISCO injection to treat the saturated soil and
groundwater in the SSZ. Two well clusters would be installed at each location to target
separate injection depths; from 50 to 62.5 ft bis and 62.5 to 75 ft bis. A 25-ft overlapping
well spacing is assumed for the injection array. If permanent wells cannot be installed
beneath the Walker building, an alternate well installation method (i.e., angled drilling),
or oxidant injection method (such as direct push technology (DPT) injections from within
the building) would be required. Potable water from a hydrant was assumed for chemical
mixing for the oxidant solution. The alternative cost is based upon the use of KMn04
prepared in batches on-site and stored in a 6,500-gallon HDPE tank with secondary
containment prior to injection. An injection period of 30 weeks is assumed with
approximately 150,400 pounds of KMn04 injected at up to 6 wells simultaneously. The
injection process was estimated at 1.5 gpm per well with a 2% concentration of KMn04
and was based upon the average permanganate natural oxidant demand (PNOD) of 6.6
grams-KMn04/kg-soil. Treatability testing would be required to select the optimal
oxidant for the Site. The remedy also includes the installation of 10 performance
monitoring wells. A secondary injection of KMn04 at 25% of the original dose is
included as a follow-up injection during the second year of operation.
9.2.4 SSZ Alternative 4: Enhanced In Situ Bioremediation (EISB) with in situ
chemical reduction (ISCR)
Estimated Capital Costs: $2,396,036
Estimated Annual O&M Costs: $82,766
Estimated Present Worth Costs: $2,478,800
Estimated Time to Achieve RAOs/Cleanup Levels: 5 yrs
Alternative SSZ #4 involves a dense array, full coverage injection of a combined carbon
substrate with soluble ferrous iron or ZVI to reduce residual DNAPL, CVOCs adsorbed
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on saturated soil, and CVOCs dissolved in groundwater. This remedy offers the benefit of
both anaerobic biodegradation and chemical reduction treatment mechanisms. The
overall number of injection points and layout mirrors the application for ISCO discussed
in SSZ Alternative #3.
Two currently existing commercial products, Peroxychem's EHC-L and EOS
Remediation's EOSZVI were used as preliminary formulations for considering this
alternative. EHC-L provides a water-soluble soy lecithin carbon substrate and powdered
ferrous iron salt mixture and nutrients for the EISB/ISCR amendment. EOSZVI is a water
mixable soy bean oil based substrate with a micro-scale carbonyl iron with a surfactant,
and pH stabilizer. The amendment mixtures are both capable of DPT and injection well
delivery. The carbon substrate will potentially provide a long-term source of carbon
(electron donor) from 2 to 5 years. The ferrous iron and zero valent iron (ZVI) will
contribute to reduced conditions favorable for the development of iron sulfides in the
formation for chemical reduction.
The ISCR component of the remedy would have a faster kinetic rate for degradation
although the synergistic effect of the two technologies should be able to treat the
soil/ground water matrix within a 2-year timeframe. Effective implementation of EISB
with ISCR is dependent upon uniform amendment distribution and contact with
contaminants. The persistence of the carbon substrate and iron will allow secondary
contact with advecting COCs for an extended duration.
This alternative would include installation of 52 clusters (12 angled clusters and 40
vertical clusters) of 2-inch diameter wells for EISB/ISCR injection. The layout would be
identical to the SSZ #3 ISCO layout with two well clusters installed at each location to
target separate injection depths from 50 to 62.5 ft bis and 62.5 to 75 ft bis. The injection
array is based on a 25-ft overlapping well spacing. If permanent wells are unable to be
installed beneath the Walker building, an alternate well installation method (i.e., angled
drilling), or injection method (such as DPT injections from within the building) would be
required. Potable water from a hydrant was assumed for chemical mixing for the
EISB/ISCR solution although recovered groundwater from a groundwater recovery well
could be used. This water would require conditioning to lower the oxidation reduction
potential (ORP) and adjust the pH.
The alternative cost is based upon the use of EHC-L prepared on-site and stored in a
6,500-gallon HDPE tank with secondary containment prior to injection. An injection
period of 6 weeks is assumed with approximately 33,000 pounds (-72 drums) of EHC-L
injected at up to 6 wells simultaneously. Injection was estimated at 1.5 gpm per well with
a 5.3% (%w/w) concentration of EHC-L. Treatability testing would be required to select
the optimal EISB/ISCR amendment for the Site. A pH buffer would be required to offset
the production of acid from the reaction and to raise the natural pH to optimal levels for
biodegradation. The remedy also assumes that bioaugmentation would be required;
approximately 86 liters of 1E+06 cells per milliliter (cells/mL) of Dehalococcoides sp
(DHC) and other halorespiring bacteria would be injected into the aquifer. The remedy
also includes the installation of 10 performance monitoring wells. A secondary injection
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of EHC-L at 25% of the original dose is included as a follow-up injection during the
second year of operation.
9.2.5 SSZ Alternative 5: Biogeochemical Reductive Dehalogenation (BiRD)
Estimated Capital Costs: $1,605,753
Estimated Annual O&M Costs: $391,246
Estimated Present Worth Costs: $1,997,000
Estimated Time to Achieve RAOs/Cleanup Levels: 3 yrs
Alternative SSZ #5 consist of the BiRD technology applied to the SSZ using an injection
well and recirculation well approach. A series of hexagonal recirculation cells would be
used to inject carbon substrate, sulfate, and iron solution to reduce residual DNAPL,
CVOCs adsorbed on saturated soil, and CVOCs dissolved in groundwater. Each
hexagonal cell uses a 7-spot repeating pattern with a groundwater extraction, or
recirculation, well in the center and amendment injection wells on the hexagon vertices.
This remedy is intentionally dissimilar to Alternatives SSZ #3 (ISCO) and SSZ #4
(EISB/ISCR), which used a dense array for full injection coverage. The recirculation
scheme provides a reduced level of initial amendment distribution but offsets this with
the hydraulic flushing/recirculation and the inherent flexibility of this injection pattern.
The BiRD technology relies principally on the in-situ production of iron sulfides for
chemical reduction and is designed to leverage any indigenous divalent metals that will
facilitate this process. Biodegradation is also available as an ancillary process due to the
reduced conditions induced by adding carbon substrate to lower the ORP. As with other
in situ technologies, amendment distribution and contact with contaminants, along with
suitable soil mineralogy is important to the success of the BiRD process.
The chemical reduction component of the remedy would have a faster kinetic rate for
degradation than the biodegradation component, although the synergistic effect of the two
technologies should be able to treat the soil/groundwater matrix within a 2- to 3-year
timeframe. The persistence of the carbon substrate and iron sulfides produced from the
process will allow secondary contact with advecting COCs for an extended duration.
This alternative would include installation of twenty-eight (28) 4-inch diameter injection
wells with screen intervals from 50 to 75 ft bis. Thirteen 6-inch diameter recovery wells
would be located at the foci of the hexagonal grid approximately 30-feet from the
injection wells. This alternative assumes that angled wells will be drilled under the
Walker building. Potable water from the recovery wells was assumed for chemical
mixing for the amendment solution addition. This water would require conditioning to
lower the ORP and adjust the pH. The recirculation cells will use an injection manifold,
and an equipment trailer with air stripping, bag filtration, GAC, and supplemental water
conditioning with an oxygen scavenger for water treatment prior to reinjection. A 40-ft
by 75-ft by 3-fit deep infiltration gallery is also to be installed to handle supplemental
discharge of water as needed.
The alternative cost is based upon the use of amendments prepared on-site and stored in a
6,500-gallon HDPE tank with secondary containment prior to injection. An
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injection/recirculation period of 3 years is assumed with approximately 33,000 pounds of
carbon substrate and 8,500 pounds of iron sulfate. Injection flowrates are estimated
between 5 to 15 gpm per well. Treatability testing would be required to analyze the Site
mineralogy and select the optimal amendments for the Site. A pH buffer would be
required to offset the production of acid from the reaction and to raise the natural pH to
optimal levels for chemical reduction and biodegradation. The remedy also assumes that
bioaugmentation would be required; approximately 86 liters of 1E+06 cells/mL of DHC
and other halorespiring bacteria would be injected into the aquifer. The remedy also
includes the installation of 6 performance monitoring wells. A secondary injection of
amendments at 25% of the original dose was incorporated as a follow-up injection during
the second year of operation. The recirculation system is estimated to operate for 3 years
inclusive of 48 days of manned operation per year. A fourth year of active monitoring is
also included in the remedy.
9.3 Description of the Dilute Plume (DP) Remedy Alternatives
The DP consists of dissolved contamination in groundwater and contiguous soils that
surrounds the SSZ and which are impacted with CVOCs above cleanup levels. The DP
encompasses groundwater with total VOC concentrations between 5 and 1,500 (ig/L. The
lithology encompassed by this zone is predominantly sand with zones of interbedded
silt/clay. The CMZ depth varies across the DP. The four remedial alternatives developed
for the DP are:
9.3.1 DP Alternative 1: No Action
Estimated Capital Costs: $0
Estimated Annual O&M Costs: $40,000
Estimated Present Worth Costs: $40,000
Estimated Construction Timeframe: N/A
Estimated Time to Achieve RAOs/Cleanup Levels: N/A
The DP Zone No Action Alternative is equivalent to the UZ #1 and SSZ #1, No Action
alternatives. Minimal periodic sampling and analysis of COCs in groundwater would be
used to track contaminant concentrations over the course of a 30-year monitoring period.
9.3.2 DP Alternative 2: Groundwater Recovery and Treatment
(GR&T)/Hydraulic Containment
Estimated Capital Costs: $659,583
Estimated Annual O&M Costs: $1,159,299
Estimated Present Worth Costs: $1,818,900
Estimated Time to Achieve RAOs/Cleanup Levels: 20 yrs
Alternative DP #2 involves the use of recovery and treatment of CVOC-contaminated
groundwater to provide hydraulic containment and limited mass removal of COCs. The
recovered groundwater is then treated with air stripping and GAC and infiltrated back
into the aquifer via an infiltration gallery. This alternative is closely related in scope to
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the SSZ #2 groundwater containment scenarios except that the hydraulic containment
encompasses the DP instead of the SSZ.
This alternative would include installing transects of recovery wells oriented
perpendicular to groundwater flow. One transect would be placed along the western edge
of the Site between the Walker building and the Witt building. A second transect would
be placed along the leading edge of the DP to the west and north of the Witt building, on
the Witt property. Groundwater flow modeling will be done to confirm the number and
placement of the wells.
The seven 4-inch groundwater recovery wells would be screened across the top 25-ft of
the water table (approximately at 50 to 75 ft bis, respectively for the eastern and western
well transects). Preliminary calculations indicate that an extraction rate of 15 gpm per
well will produce a downgradient capture distance of 75-feet without excessive
drawdown induced at the extraction wells. The formation may be capable of yielding
higher flowrates of approximately 25 gpm. The proposed well locations can provide full
areal coverage of the DP inclusive of the upgradient SSZ zone. Confirmation of the
aquifer hydraulic conductivity and soil infiltration rate are critical data gaps for this
alternative.
Recovered groundwater would be treated by an ex situ treatment train consisting of a tray
air stripping unit and carbon adsorption like the system described in SSZ #2. Treated
effluent can be either discharged into an infiltration gallery (nominally 6000-ft2 by 3-ft
deep). The gallery size and feasibility is predicated upon infiltrometer testing to
determine the permissible loading rate. Injection wells could be used in lieu of an
infiltration gallery but would nominally require twice the screen interval of the recovery
wells.
In the absence of source reduction, this alternative may result in the spreading of
dissolved COCs away from the source areas to the recovery wells and taking a significant
amount of time to capture all contamination. Thus, this remedy is most suitable when
combined into a site-wide alternative. This remedy can provide substantial containment
of the dissolved COCs in the DP, but has potential drawbacks due to the smearing of
contamination within the containment area, and likely longer-term operation costs.
9.3.3 DP Alternative 3: EISB Passive Barrier Wells and a Horizontal Well
Estimated Capital Costs: $1,448,081
Estimated Annual O&M Costs: $ 1,001,623
Estimated Present Worth Costs: $2,449,700
Estimated Time to Achieve RAOs/Cleanup Levels: 20 yrs
Alternative DP #3 involves the use of EISB passive barriers consisting of injection wells
across the DP coupled with a horizontal injection well for the toe of the DP. The injection
wells would be injected with emulsified oil substrate supplemented with bioaugmentation
and pH adjustment to accelerate biodegradation via direct anaerobic reductive
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dechlorination of CVOCs in groundwater. The treatment barriers would be emplaced
solute barrier wells that would not alter or impede groundwater transmissivity.
This alternative would include the installation of sixteen (16) 2-inch diameter wells with
28-ft spacing between the wells for injection of emulsified oil substrate. The wells would
be screened from approximately 60 to 85 ft bis. A 4-inch diameter 730-ft long horizontal
(directionally drilled) well (430-ft screen with 300 feet of riser at one end) would also be
installed at approximately 73 ft bis (mid-depth into the DP). A blind (no exit boring)
installation is presumed, but the well could be constructed with either approach. The well
screen can be configured to augment the vertical distribution along this barrier. If a
directionally drilled well is deemed untenable due to property access or modeling
indicates the vertical distribution may be insufficient, the DP #3 remedy component can
be altered to a series of approximately 23 injection wells along the west and north edges
of the Witt property for an equivalent cost.
The emulsified oil carbon substrate will potentially provide a long-term source of carbon
(electron donor); from 2 to 5 years for treatment of the advected COC flux. The relatively
close spacing will provide good coverage along the barrier. In addition, a zone of reduced
conditions will develop downgradient from the barriers. Potable water from a hydrant
was assumed for chemical mixing for the EISB solution although recovered groundwater
from a groundwater recovery well could be used. This water would require conditioning
to lower the ORP and adjust the pH.
The alternative cost is based upon the preparation of substrate solution on-site and stored
in a 6,500-gallon HDPE tank prior to injection. An injection period of 4 weeks is
assumed with approximately 94,500 pounds of emulsified oil injected at up to 6 wells
simultaneously. Injection was estimated at 4 gpm per well. Treatability testing would be
required to select the optimal EISB amendment for the Site. A pH buffer would be
required to offset the production of acid from the reaction and to raise the natural pH to
optimal levels for biodegradation. The remedy also assumes that bioaugmentation would
be required; approximately 86 liters of 1E+06 cells/mL of DHC and other halorespiring
bacteria would be injected into the aquifer. The remedy includes the installation of 4
performance monitoring wells. A secondary injection of emulsified oil at 25% of the
original dose is included as a follow-up injection during the first five years of operation.
A total operation of 15 years was assumed, this period being contingent upon the
effectiveness of upgradient source reduction.
9.3.4 DP Alternative 4: Monitored Natural Attenuation (MNA)
Estimated Capital Costs: $0
Estimated Annual O&M Costs: $187,100
Estimated Present Worth Costs: $187,100
Estimated Time to Achieve RAOs/Cleanup Levels: 30 yrs
Alternative DP #4 MNA may be a viable supplemental alternative for the DP zone when
used in conjunction with treatment of source areas/higher concentration areas. MNA is
the use of natural biotic degradation or natural abiotic degradation (e.g., due to reduced
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iron species, soil attenuation, advection, dispersion, dilution, etc.) for contaminant
reduction. Due to the aerobic groundwater conditions and limited presence of PCE/TCE
daughter products, natural biotic degradation is not thought to be particularly active for
the Site. The downgradient edge of the dissolved plume is essentially in equilibrium,
presumably due to natural abiotic reduction.
As a stand-alone treatment option, MNA is likely not an effective biotic treatment due to
the naturally high DO and ORP levels. Microbial populations of halorespiring bacteria
have not been analyzed for the Site, but are not expected to be present in significant
concentrations. Abiotic degradation, while occurring, is slow. There is insufficient
information concerning the extent and magnitude of the source to develop a predictive
solute transport model for the likely duration of an MNA with or without source
reduction.
This remedy uses analyses of COCs and natural attenuation parameters (NAPs) from
monitoring wells to gauge the effectiveness of natural biotic and abiotic degradation
mechanisms. The difference between this remedy and an active EISB remedy is that
carbon and nutrient levels are not enhanced and there is no effort made to stimulate or
augment the existing dechlorinating bacteria. The historical analyses of total VOCs and
NAPs indicate that biotic degradation may be occurring as evidenced by the presence of
PCE daughter products. This degradation requires reduced conditions, so it is assumed
that isolated pockets of low permeability zones exist with correspondingly lower
groundwater velocities and oxygen flux.
This remedy will be ineffective without source area treatment and will require an
extended time for site restoration (estimated at 30 years) even if the source areas are
addressed.
9.3.5 Institutional Controls
ICs are non-engineering measures which include legal and administrative controls to
affect human activities in such a way as to prevent or reduce the potential for exposure to
contamination until cleanup goals are achieved. The purpose of the ICs is to impose on
the subject property "use" restrictions for the purpose of implementing, facilitating and
monitoring a remedial action to reduce exposure, thereby protecting human health and
the environment. Often ICs are more effective if they are layered or implemented in
series. Layering can involve using different types of ICs at the same time to help ensure
the protectiveness of the response action. ICs will be necessary at the Site to protect the
integrity of the groundwater remedy and to prevent unacceptable exposure to
contaminated groundwater and VOC vapors from soil gas as part of the selected remedy.
Construction of a building or other structure oyer contaminated areas with VOC soil gas
may require mitigation systems or construction techniques to prevent VOC vapors
entering the structure. Similarly, continued operation of the existing sub-slab ventilation
system at the current Walker building will be required to reduce the potential for vapor
intrusion until cleanup goals are met. Some of the controls which may be implemented or
relied upon for the Site include, but are not limited to, the following:
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• Governmental controls, such as local zoning/land use ordinances and local
permitting requirements to limit potential exposure of Site users to the COCs. The Site is
currently zoned general industrial and is anticipated to remain subject to this land use
classification. In addition, the Ground Water Quality Control Board for Shelby County
has established water-well regulations that include permit requirements. The regulations
include specific requirements for placement of water wells within a half-mile of a listed
Superfund site. The Memphis Sand aquifer is the municipal water supply for the residents
near the Site.
• Proprietary controls, such as deed and land use restrictions (i.e., a restrictive
covenant executed by the landowner and recorded in Shelby County) will also be utilized
at the Site until cleanup goals are determined by EPA to have been met. Prohibited
activities under the restrictive covenant will include, but not be limited to the following:
the installation of groundwater wells at the Site; the use of groundwater at the Site; any
disturbance of engineered remedy components at the Site such as monitoring wells, vapor
intrusion mitigation/ventilation equipment, and the existing building slab.
9.4 Distinguishing Features of Each Alternative
The following chart summarizes the advantages and disadvantages of each of the
alternatives.
Alternative: No Action for all Alternatives UZ #1, SSZ #1, DP #1
Criteria
Analysis
Advantages
Low cost, no site disruption
Disadvantages
• Site would remain in current condition, no added protection of human health and
the environment.
• The potential for further contaminant migration in groundwater.
• The potential of VI from subsurface contamination into the Walker building would
remain.
Alternative: UZ #2a SVE with Limited Air Sparging
Advantages
• SVE is a presumptive remedy for CVOCs in unsaturated soil, well proven and
reliable.
• Likely reduce or eliminate VI into the Walker building, mitigating inhalation
hazards associated with indoor air.
• SVE is a dynamic process, remedial results can be interpreted and adjustments
made; SVE wells can also be used for performance measurements.
• Air sparging is a well proven technology for the CVOC volatility.
• Recovered COC vapors are fully treated (via final treatment for carbon
regeneration); toxicity/mobility/volume (T/M/V) are all reduced.
• Excavated soils have eliminated toxicity and volume relative to Site.
Disadvantages
• Active use of the Walker building may prevent optimal placement of SVE and air
sparge wells and will require angled drilling.
• Low permeability clay layers may hinder subsurface air flow and recovery of
volatilized contaminants, especially for sparge flow.
• Large screen intervals may result in non-uniform SVE coverage.
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Alternative: UZ #2b TE-SVE with Limited Air Sparging
Advantages
• TE-SVE treatment is very aggressive approach with faster COC removal
efficiencies due to elevated vapor pressures and increased desorption.
• TE-SVE is more amenable to DNAPL treatment and is advantageous in treating
low permeability media.
• SVE is a presumptive remedy for CVOCs in unsaturated soil, well proven and
reliable.
• Approach will essentially eliminate the potential for VI in the Walker building.
• TE-SVE is a dynamic process, remedial results can be interpreted and adjustments
made; SVE wells can also be used for performance measurements.
• Air sparging is a well proven technology for volatility of CVOCs.
• Recovered COC vapors are fully treated (via final treatment for carbon
regeneration); T/M/V are all reduced.
• Excavated soils have eliminated toxicity and volume relative to Site.
Disadvantages
• Cost is very high, more viable if a higher concentration source area identified.
• Active use of the Walker building may prevent optimal placement of SVE and air
sparge wells and heater borings and will require angled drilling.
• Low permeability clay layers may hinder subsurface air flow, especially for sparge
air, and recovery of volatilized contaminants.
• Subsurface materials must be thermally compatible.
• Large screen intervals may result in non-uniform SVE coverage.
Alternative: UZ #3 Limited Soil Excavation with SVE
Advantages
• Shallow soil excavation to 20 ft bis removes a larger volume of potentially
contaminated soil with the highest contaminant mass from the Site.
• Excavation eliminates direct contact hazard in suspected source areas.
• Ample room to stockpile soils and stage remedy.
• Short remediation timeframe for excavation.
• SVE is a presumptive remedy for CVOCs in unsaturated soil, well proven and
reliable.
• Likely reduce or eliminate VI into the Walker building, mitigating inhalation
hazards associated with indoor air.
• SVE is a dynamic process, remedial results can be interpreted and adjustments
made; SVE wells can also be used for performance measurements.
• Recovered COC vapors are fully treated (via final treatment for carbon
regeneration); T/M/V are all reduced.
Disadvantages
• Some long-term liability for landfill in perpetuity.
• Potential for structural impacts to building, but manageable.
• More disruption in vicinity from excavation and soil truck transport.
• Higher relative capital cost.
• Active use of the Walker building may prevent optimal placement of SVE wells
and will require angled drilling.
• Low permeability clay layers may hinder subsurface air flow.
• Large screen intervals may result in non-uniform SVE coverage.
Alternative: UZ #4ISCO and SVE
Advantages
• ISCO destroys contaminants rapidly; net reduction in T/M/V.
• ISCO applicable to NAPL treatment (if found to be present).
• Site NOD was low to moderate.
• Distribution of visible purple oxidant can be inferred through soil borings.
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• SVE is a presumptive remedy for CVOCs. in unsaturated soil, well proven and
reliable.
• Likely reduce or eliminate VI into the Walker building, mitigating inhalation
hazards associated with indoor air.
• SVE is a dynamic process, remedial results can be interpreted and adjustments
made; SVE wells can also be used for performance measurements.
• Recovered COC vapors are fully treated (via final treatment for carbon
regeneration); T/M/V are all reduced.
Disadvantages
• Heterogeneous formation may impede vertical transport or flood; may not follow
same pathways as COC release.
• Uniform sheet flow from laterals may not be achieved; depth of UZ may impair
hydraulic contact.
• Efficiency of remedy is directly proportional to oxidant contact.
• Dosing must be monitored to optimize retention in UZ.
• Selection of chemical oxidant dosing requires treatability testing.
• Active use of the Walker building may prevent optimal placement of SVE wells
and will require angled drilling.
• Low permeability clay layers may hinder subsurface air flow.
• Large screen intervals may result in non-uniform SVE coverage.
Alternative: SSZ #2 Groundwater Recovery and Treatment/Hydraulic Containment
Advantages
• Presumptive remedy; well proven and reliable for hydraulic containment.
• Would reduce concentrations of contaminants migrating towards municipal wells.
• Moderate to highly transmissive aquifer.
Disadvantages
• Contamination removal is marginal; long-term reduction in T/M/V.
• Limited short-term mass removal; subsurface heterogeneities may result in
preferential flow paths.
• Requires extended long-term O&M.
• Need for ex situ groundwater treatment and disposal.
Alternative: SSZ #31SCO
Advantages
• ISCO destroys contaminants rapidly; net reduction in T/M/V.
• Proven, robust, flexible technology.
• Applicable to NAPL treatment (if found to be present).
• Not dependent on reducing conditions (aquifer conditions are oxidizing).
• Site NOD was low to moderate.
• Distribution of visible purple oxidant can be inferred through soil borings.
• No aboveground treatment required.
Disadvantages
• Heterogeneous formation may limit contaminant contact with oxidant in less
permeable soil; efficiency of remedy is directly proportional to oxidant contact.
• Selection of chemical oxidant dosing requires treatability testing.
• Method of injection may be limited, angled drilling needed beneath the building.
Alternative: SSZ #4 EISB with in situ chemical reduction (ISCR)
Advantages
• CVOCs proven to be destroyed via a number of reducing reactions; net reduction
in T/M/V.
• Proven and flexible technology.
• Chemical reductants may destroy CVOCs rapidly and completely via abiotic
process (abiotic degradation may already be occurring to some extent at the Site).
• Can practically remediate low volumes of residual NAPL (if found to be present).
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• Cost for this remedy is relatively lower.
• No aboveground treatment required.
Disadvantages
• Dependent on reducing conditions; Site geochemistry is characterized as being
aerobic and oxidized.
• Dependent on adjustment to a suitable pH for biodegradation; presumed need for
addition of suitable halorespiring bacteria.
• Evaluation of indigenous bacteria and quantification of reductant and amendment
dosing requires field or treatability testing.
• Substantial redox adjustment via carbon substrate addition required. Any reinjected
groundwater would have to be conditioned to a reduced state, and adjusted for pH.
• Heterogeneous formation may restrict reductant/amendment distribution.
• Method of injection may be limited such as angled drilling beneath the building.
Alternative: SSZ #5 Biogeochemical Reductive Dehalogenation (BiRD)
Advantages
• C^OCs proven to be destroyed via a number of reducing reactions; net reduction
in jT/M/V.
• Flexible technology; more so due to recirculation scheme; recirculation allows
dynamic monitoring of COC levels in cell and real-time adjustments in hydraulic
regime.
• Chlorinated daughter products (DCE, VC) are not produced.
• Reducing conditions also promote anaerobic biotic degradation.
• Contaminated groundwater would remain in situ during treatment.
• Can practically remediate low volumes of residual NAPL (if found to be present).
• Cost for this remedy is relatively lower.
Disadvantages
• Potential for back diffusion of COCs if sufficient iron sulfides cannot be generated
or supplemental amendments are expended
• Creation of sustainable conditions may be complicated in aerobic aquifer with
moderate groundwater flow.
• Proven technology but not widely implemented to date.
• Dependent on production of reducing conditions; Site geochemistry is
characterized as being aerobic and oxidizing.
• Dependent on establishment of suitable pH and bioaugmentation.
• Morphological, mineralogical, and biotic geochemical evaluation would be needed
to fully evaluate technology efficacy.
• Heterogeneous formation may limit amendment distribution and iron sulfide
formation.
• Aboveground treatment and redox adjustment required for recirculation.
Alternative: DP #2 Groundwater Recovery and Treatment (GR&T)/Hydraulic Containment
Advantages
• Presumptive remedy; well proven and reliable for containment.
• Would prevent migration of contamination to municipal wells.
• Moderate to highly transmissive aquifer, good lithology for GR&T.
• Provides good coverage under Witt building.
• Hydraulic containment of all COCs on Site.
Disadvantages
• Contamination removal is marginal; long-term reduction in T/M/V.
• Limited short-term mass removal; subsurface heterogeneities may result in
preferential flow paths.
• Requires long-term O&M.
• Need for ex situ groundwater treatment and disposal.
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• Off-facility access for well installation and operation, trenching to wells.
• Long timeframe for O&M with significant O&M costs.
Alternative: DP #3 EISB Passive Barrier Wells and a Horizontal Well
Advantages
• CVOCs proven to be destroyed via a number of reducing reactions; net reduction
in T/M/V.
• Proven and flexible technology.
• Separates on-site source area from remainder of DP treatment via solute barrier that
would not appreciably alter groundwater transmissivity.
• Chemical reductants may destroy CVOCs rapidly and completely via abiotic
process (abiotic degradation may already be occurring to some extent at the Site).
• Cost for this remedy is typically low. ,
• No aboveground treatment required.
• No disruption to Witt property; one entry well location off property.
• Good synergy with several SSZ remedies.
Disadvantages
• Dependent on reducing conditions; Site geochemistry is characterized as being
aerobic and oxidized.
• Long term maintenance of biobarrier could require additional injections, thus
remedy is keyed to SSZ treatment effectiveness.
• Evaluation of indigenous bacteria and quantification of reductant and amendment
dosing requires field and/or treatability testing.
• Substantial redox adjustment, bioremediation amendment addition, and
bioaugmentation may be required. Any reinjected groundwater would have to be
conditioned to a reduced state and adjusted for pH.
• Heterogeneous formation may limit reductant/amendment distribution.
• Horizontal well may not adequately distribute bio-amendments in vertical plane.
Alternative: DP #4 MNA
Advantages
• Easy to implement.
• Some indication of abiotic degradation of CVOCs occurring off-site at plume
periphery.
• Plume appears to be relatively stable.
• May be practical in combination with treatment/control of source area.
• Low cost.
Disadvantages
• Large plume; has migrated off-facility.
• Site geochemistry is oxidizing; biotic reductive dechlorination is not likely a
predominant degradation process.
• Long-term prognosis for reduction of higher contaminant concentrations.
• Not protective of Collierville well field.
10.0 Comparative Analysis of Alternatives
The NCP establishes a framework of nine criteria for evaluating remedial alternatives.
Each alternative must meet the threshold criteria of protection of human health and the
environment and compliance with ARARs to be considered for further evaluation against
the five balancing criteria. The FS used a comparative analysis to assess the relative
performance of each alternative in relation to the nine criteria. The purpose of this
analysis was to identify the advantages and disadvantages of each alternative relative to
the other alternatives. Analysis of alternatives was conducted separately for each of the
three CMZs although consideration was given to the other CMZs.
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10.1 Overall Protection of Human Health and the Environment
Overall protection of human health and the environment addresses whether each
alternative provides adequate protection of human health and the environment and
describes how risks posed through exposure pathway are eliminated, reduced or
controlled, through treatment, engineering controls and/or ICs.
The No Action Alternatives would not provide protection of human health and the
environment.
Alternatives UZ #2a, UZ #2b, UZ #3 and UZ#4 are protective of human health and the
environment. Alternative UZ #2b (TE-SVE with Limited Air Sparging) should provide
nearly complete removal of COCs from a portion of the zone and vapor removal of COCs
from the remaining portion of the zone. Alternative UZ #3 (i.e., Limited Soil Excavation
with SVE) will remove COCs from the upper 20-feet of the UZ.
Alternatives SSZ #2, SSZ #3, SSZ #4 and SSZ #5 are protective of human health and the
environment. With Alternative SSZ #3 (ISCO), the highest levels of source area
contamination would quickly be chemically destroyed in situ. However, this assumes that
the dense array injection and repeated injection of hot spots will attain sufficient contact
with the COCs. Alternatives SSZ #4 (EISB with ISCR) and SSZ #5 (BiRD) rely on
reducing geochemical conditions and the potentially longer treatment timeframe. With
GR&T/hydraulic containment (SSZ #2), the contaminants will not be destroyed and
contaminated groundwater would be treated ex situ, resulting in potential aboveground
exposures. In addition, this alternative would not provide any potential ancillary
downgradient treatment of the DP as other alternatives might due to injection of
treatment chemicals/amendments.
Alternatives DP #2, DP #3, DP #4 are protective of human health and the environment.
With Alternative DP #2 (GR&T/hydraulic containment) the dissolved contamination is
hydraulically contained and prevented from migrating any farther toward the municipal
wellfields. Alternative DP #3 (EISB passive barriers with horizontal well) treats the
dissolved COCs in situ via biological treatment barrier using vegetable oil. It also
includes a downgradient biobarrier treatment zone to treat the toe of the plume. The
MNA alternative (DP#4) is expected to be protective, but it will take much longer to
achieve cleanup goals. The No Action alternative would not be protective since there
would be no method to address off-site contaminant migration or collect appropriate data
to confirm natural attenuation.
10.2 Compliance with ARARs
Section 121(d) of CERCLA and NCP §300.430(f)(l)(ii)(B) require that RAs at CERCLA
sites attain legally applicable or relevant and appropriate federal and more stringent state
requirements, standards, criteria, and limitations which are collectively referred to as
"ARARs," unless such ARARs are waived under CERCLA section 121(d)(4). Applicable
requirements are those cleanup standards, standards of control, and other substantive
requirements, criteria, or limitations promulgated under Federal environmental or State
environmental or facility siting laws that specifically address a hazardous substance,
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pollutant, contaminant, RA, location, or other circumstance found at a CERCLA site.
Relevant and appropriate requirements are those cleanup standards, standards of control,
and other substantive requirements, criteria, or limitations promulgated under Federal
environmental or State environmental or facility siting laws that, while not "applicable"
to a hazardous substance, pollutant, contaminant, RA, location, or other circumstance at a
CERCLA site address problems or situations sufficiently similar to those encountered at
the CERCLA site that their use is well-suited to the particular site.
ARARs do not include occupational safety or worker protection requirements.
Compliance with OSHA standards is separately required by 40 CFR §300.150.
Under CERCLA Section 121(e)(1), federal, state, or local permits are not required for the
portion of any removal or remedial action conducted entirely 'on-site' as defined in 40
CFR §300.5. See also 40 CFR §300.400(e)(l) & (2). Also, CERCLA response actions
must only comply with the "substantive requirements," not the administrative
requirements of a regulation or law. Administrative requirements include permit
applications, reporting, record keeping, inspections, and consultation with administrative
bodies. Although consultation with state and federal agencies responsible for issuing
permits is not required, it is often recommended for determining compliance with certain
requirements such as those typically identified as location-specific ARARs.
In addition to ARARs, the lead and support agencies may, as appropriate, identify other
advisories, criteria, of guidance to be considered for a particular release that may be
useful in developing Superfund remedies. See 40 CFR §300.400(g)(3). The "to-be-
considered" (TBC) category consists of advisories, criteria, or guidance that were
developed by EPA, other federal agencies, or states that may assist in determining, for
example, health-based levels for a particular contaminant for which there are no ARARs
or the appropriate method for conducting an action. TBCs are not considered legally
enforceable and, therefore, are not considered to be applicable for a site but typically are
evaluated along with Chemical-specific ARARs as part of the risk assessment to
determine protective cleanup levels. See EPA, Office of Solid Waste and Emergency
Response (OSWER) Directives No. 9234.1-01 and 9234.1-02, CERCLA Compliance
with Other Laws Manual: Parts 1 and Part II, Section 1.4.
For purposes of ease of identification, the EPA has created three categories of ARARs:
Chemical-, Location- and Action-Specific. Under 40 CFR §300.400(g)(5), the lead and
support agencies shall identify their specific ARARs for a particular site and notify each
other in a timely manner as described in 40 CFR §300.515(d).
Chemical-Specific ARARs/TBC Guidance
Chemical-specific ARARs are usually health or risk-based numerical values limiting the
amount or concentration of a chemical that may be found in, or discharged to, the
environment. The selected remedy is expected to attain the chemical-specific ARARs
listed in Table 24, which include the Safe Drinking Water Act National Primary Drinking
Water Regulations Maximum Contaminant Levels (MCLs) and TDEC Regulation 0400-
40-03. Where an MCL has not been established for a particular site COC, the cleanup
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standard for the COC was based on HHRA cancer risk levels or non-cancer hazard levels,
as appropriate.
Location-Specific ARARs/TBC Guidance
Location-specific requirements establish restrictions on permissible concentrations of
hazardous substances or establish requirements for how activities will be conducted
because they are in special locations (e.g., wetlands, floodplains, critical habitats,
streams). The location-specific ARARs for the remedial action are listed in Table 25.
Action-Specific ARARs/TBC Guidance
Action-specific ARARs are usually technology-based or activity-based requirements or
limitations that control actions taken at hazardous waste sites. Action-specific
requirements often include performance, design and controls, or restrictions on particular
kinds of activities related to management of hazardous substances. Action-specific
ARARs are triggered by the types of remedial activities and types of wastes that are
generated, stored, treated, disposed, emitted, discharged, or otherwise managed. The
Action-specific ARARs for the remedial action are listed in Table 26. Potential action-
specific ARARs include federal and state requirements for general construction
management requirements (preventing fugitive dust and control of stormwater runoff
from land disturbing activities), underground injection control (UIC well regulations for
injecting reagents to remediate groundwater), UIC and monitoring well construction,
operation, and abandonment requirements; air emission limitations for treating VOC
contaminated groundwater, and RCRA waste characterization, treatment, storage and
disposal requirements for soils and secondary wastes that are generated by remedial
activities.
Compliance with Identified ARARs
In accordance with 40 CFR §300.400(g), EPA and TDEC have identified the potential
ARARs and TBCs for the evaluated alternatives.
All CMZ alternatives, except the No Action alternatives, are compliant with action-
specific, location-specific and chemical-specific ARARs. UZ #2b, (TE-SVE with Limited
Air Sparging) is projected to be the most aggressive source treatment alternative which
will ultimately lead to achievement of the groundwater cleanup levels. It is expected to
have the most comprehensive successes at reducing the mass and concentration of
contaminants, and should do so in a short timeframe. Alternatives SSZ #3 and SSZ #4 are
projected to be roughly equivalent and are the most aggressive treatment alternatives for
meeting groundwater cleanup levels . DP #3 (EISB Passive Barrier Wells and a
Horizontal Well) is expected to have the most comprehensive successes at reducing the
mass and concentration of contaminants via treatment.
10.3 Long-Term Effectiveness and Permanence
Long-term effectiveness and permanence refers to expected residual risk and the ability
of a remedy to maintain reliable protection of human health and the environment over
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time, once clean-up levels have been met. This criterion includes the consideration of
residual risk that will remain on-site following remediation and the adequacy and
reliability of controls.
All the alternatives, except the No Action alternatives, provide some degree of long-term
protection. TE-SVE with Limited Air Sparging (UZ #2b) would be the most aggressive in
removing contamination over the entire depth of the UZ (over the areal extent of the
SSZ), including any contaminated lower permeability soils in this area that may be
difficult to treat with other methods. Alternatives SSZ #3 and SSZ #4 are projected to be
roughly equivalent and are the most aggressive treatment alternatives for meeting soil and
groundwater cleanup levels. They are expected to have the most comprehensive
successes at reducing the mass and concentration of contaminants. The long-term
effectiveness of Alternative DP #3 is considered best due to active treatment and
destruction of contaminants^ Groundwater is expected to reach all MCLs and HHRA-
based cleanup standards within an estimated twenty years.
10.4 Reduce Toxicity, Mobility or Volume through Treatment
Reduction of toxicity, mobility or volume (T/M/V) through treatment refers to the
anticipated performance of the treatment technologies that may be included as part of a
remedy.
The No Action Alternatives would not reduce the T/M/V through treatment.
Alternative UZ #2b followed by UZ #3 and UZ #4 are expected to have the most
comprehensive successes at reducing the mass, volume, and concentration of on-site
contaminants in unsaturated soil in a short timeframe. Three of the SSZ alternatives (SSZ
#3, SSZ #4, and SSZ #5) are active treatment approaches that destroy contaminants;
hence the expected reduction of toxicity, mobility, and volume is an advantage for these
approaches. Alternatives DP#2 and DP#3 both include treatment of contaminants, but
alternative DP #3 is an active treatment approach that destroys contaminants in-situ;
hence the expected reduction of toxicity, mobility, and volume is an advantage for this
approach.
10.5 Short-Term Effectiveness
Short-term effective addresses the period of time needed to implement the remedy and
any adverse impacts that may be posed to workers, the community and the environment
during construction and operation of the remedy until cleanup levels are achieved.
All four active UZ remedies have average timeframes for achieving RAOs over the entire
treatment area since their primary component (SVE) is limited by non-uniform air contact
with soils. However, Alternative UZ #2b is expected to achieve RAOs most quickly in
over the areal extent of the SSZ due to the thermal enhancement of SVE. Alternative UZ
#4 was ranked the highest among active remedies as it will produce only minor Site
disruption (thus more protective of the community) relative to excavation and includes
the ISCO component that should accelerate meeting RAOs. Although removal of
contamination would occur relatively quickly for a portion of the UZ, the excavation
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component of UZ #3 would increase the potential for impacts to the community and
workers, although these issues can be effectively managed. The primary difference
between the alternatives is the time period before RAOs are met. SSZ #2
(GR&T/hydraulic containment) was scored low because it is anticipated to require long
term operation & maintenance (O&M) and requires ex situ groundwater treatment. The
two active alternatives (DP #2 and DP #3) provide good short-term effectiveness. DP #2
is considered slightly more protective of workers and the community during remedial
action since it includes capture of the toe of the plume and would prevent migration
toward the municipal well field. DP #3 is expected to achieve RAOs more quickly than
the other alternatives since it includes active in situ treatment. They are both equally
protective of workers and the community during remedial action. The primary difference
between the alternatives is the time period before RAOs are met.
10.6 Implementability
Implementability addresses the technical and administrative feasibility of a remedy from
design through construction and operation. Factors such as availability of services and
materials, administrative feasibility, and coordination with other governmental entities
are also considered.
All the treatment alternatives are easily implemented. All materials and services needed
for implementation are readily and commercially available. The site logistics of
implementation increase in difficulty as more treatment components are added in each
alternative. Alternative UZ #2a would be slightly more difficult to construct due to the
number of wells and additional remediation equipment required. Alternative UZ #4
would be slightly more difficult to implement due to the heterogeneous clay layer that
may hinder vertical transport of chemical oxidant. SSZ #5 was scored slightly lower due
to the higher complexity of the geochemical reactions. Alternatives SSZ #3 and SSZ #4
could have implementation impacts relative to injecting beneath or adjacent to an
occupied building. Conversely, SSZ #5 is configured to avoid the building using fewer
angled wells. DP #3 offers more complexity due to the installation of the directionally
drilled well under the Witt building.
10.7 Cost
Cost estimates, including capital costs and long-term operating costs, were prepared for
each alternative, and are summarized in the Tables 27-29. There are no capital costs
associated with the No Action Alternatives. Costs for the implementation of Five-Year-
Reviews, groundwater monitoring and institutional controls are included as the Site-Wide
Costs. These O&M costs were estimated separately as they apply to all remedy alternatives
until cleanup goals are met at the Site. The cost estimates were based on a 7% discount
rate.
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10.8 State Acceptance
State acceptance indicates whether the state supports, opposes, and/or has identified any
reservations with the selected response measure based on its review of the RI/FS reports
and the Proposed Plan.
The State of Tennessee has been involved actively in the process of determining and
evaluating the Walker Machine cleanup alternatives. The state has expressed support for
the selected remedy which includes alternatives UZ #2b, SSZ #5 and DP #3. The State
recommends a phased approach beginning with the UZ alternative with appropriate
monitoring before proceeding with the SSZ and DP alternatives. TDEC concurrence
letter is included as Appendix B.
10.9 Community Acceptance
Community acceptance summarizes the public's general response to the response
measures described in the Proposed Plan and the RI/FS reports. This assessment includes
determining which of the response measures the community supports, opposes, and/or
has reservations about.
During the public comment period, the community did not express a strong opinion
regarding the preferred alternative.
11.0 Principal Threat Waste (PTW)
The NCP establishes an expectation that EPA will use treatment to address the principal
threats posed by a site wherever practicable (NCP §300.430(a)(l)(iii)(A)). Identifying
principal threat waste combines concepts of both hazard and risk. In general, principal
threat wastes are those source materials considered to be highly toxic or highly mobile,
which generally cannot be contained in a reliable manner or would present a significant
risk to human health or the environment should exposure occur.
The contaminated soils under the main building and south of the main building are
considered to be the principal threat wastes at this Site. Information about site operations
coupled with the documented groundwater impacts indicate that contaminants in soil are
present and are highly mobile. It is noted that soil data collected to date do not
quantitatively confirm high concentrations and that additional data will be collected
during the remedial design (RD).
12.0 Selected Remedy
Alternative UZ #2b (TE-SVE with Limited Air Sparging) is the selected remedy for
unsaturated soil contamination. Alternative SSZ #5 (BiRD) is the selected remedy for the
SSZ. Alternative DP #3 (EISB Passive Barrier Wells and a Horizontal Well) is the
selected remedy for the DP.
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12.1 Summary of the Rationale for the Selected Remedy
The intent of the selected remedy is to reduce concentrations of VOCs in soil that are
contributing to groundwater contamination under the Site and downgradient properties as
well as vapor intrusion in the main building at the Site. The approach is to first focus on
the likely source areas onsite and the highest groundwater concentrations which are also
found in monitoring wells onsite. A phased response action is recommended for the Site.
The use of a phased approach would allow EPA to mitigate more immediate site-specific
threats while concurrently collecting additional characterization data to determine if all
three CMZ remedies will ultimately be necessary to attain the long-term objectives.
The inclusion of thermal enhancement for the SVE system for the UZ was based on
experience with other sites in the Memphis area with similar contaminants and geology.
SVE alone may not be capable of meeting the cleanup levels for subsurface soil where
silts or clays are present. The inclusion of limited air sparging for onsite groundwater was
again based on devoting resources to the area of highest concentrations first, particularly
near the oil water separator, with an expectation that groundwater quality would also
improve in nearby downgradient wells. The targeted excavation included in the UZ
remedy addresses the most likely source areas that are accessible outside the building
such as the oil water separator, the area with a few drum remnants in the woods south of
the building, and an area near the SE corner of the building. The area near the SE corner
of the building is the location of the highest TCE reading from a previous passive soil gas
survey and is the location of a stained area in historical aerial photographs. It is possible
that there is VOC contaminated soil under the building slab based on the soil gas data
collected during the RI and the expansion of the building over areas of stained soil as
seen in historical aerial photographs.
The BiRD approach was selected for the SSZ to address the contaminated groundwater
on-site outside the bounds of the planned air sparging. It is an in-situ remedy that is
expected to achieve cleanup goals faster than a typical pump and treat approach. The
recirculation capability of the BiRD approach should also improve distribution of the
injectate compared to a typical injection approach like ISCO.
The EISB approach was selected for the DP because it was likely to achieve cleanup
goals faster than a traditional pump and treat approach. In addition, the EISB approach
was thought to be more efficient at treating the lower contaminant concentrations that are
dispersed downgradient of the Site.
The available data is sufficient to select these remedies, but additional data should be
collected during the RD to more exactly refine each phase. For example, additional soil
contaminant concentration and distribution data is recommended to better locate the
various planned SVE, heater, or air sparge wells. The monitoring wells should be
sampled again to further define trends in the concentrations and extent of the VOC plume
in groundwater. Vapor intrusion sampling should be repeated in the main building to
confirm that the interim subslab vent system is performing as expected.
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These alternatives were chosen based on the comparative analysis of all the alternatives.
The selected remedy meets the threshold criteria and provides the best balance of
tradeoffs among the other alternatives with respect to balancing and modifying criteria.
The EPA and the TDEC determined that the Preferred Alternative presented in the
Proposed Plan best satisfies the nine criteria of the NCP as compared to the other
alternatives.
Based on the information available at this time, the EPA and the TDEC believe that the
selected remedy combination satisfies the following statutory requirements of CERCLA
Section 121(b) and Section 121(d): 1) protects human health and the environment; 2)
complies with ARARs; 3) is cost effective; 4) utilizes permanent solutions and alternative
treatment technologies or resource recovery technologies to the maximum extent
practicable; and 5) satisfies the preference for treatment as a principal element.
12.2 Description of the Selected Remedy
12.2.1 Unsaturated Soil Zone
TE-SVE with Limited Air Sparging (UZ #2b) is the selected remedy for unsaturated soil
contamination.
This remedy, as estimated in the FS, includes:
• ten 4-inch diameter permanent angled SVE wells installed beneath the Walker
building
• two 2-inch diameter 260-ft long horizontal utility bored vapor recovery wells
approximately 5 to 10 ft bis as an added protection from VI into the Walker
building.
• forty-three 4-inch diameter permanent vertical SVE wells installed under the
building and south of the buildings that are screened from 5 to 50 ft bis with an
average 20-ft SVE radius of influence.
• six permanent vapor monitoring points to collect chemical and vacuum readings.
• thermal enhancement (as needed) includes 63 heater borings with an average 25-ft
spacing to heat unsaturated soil from 5 to 55 ft bis, six temperature monitoring
points, and TCH equipment including power supply, power distribution system,
and other ancillary equipment. A target temperature of approximately 160°F is
specified to promote enhanced volatilization and desorption. Well materials and
conveyance piping that lie within the SSZ area will be selected to operate at the
higher temperature.
• the ancillary air sparge system includes forty-four, 2-inch permanent air sparge
wells with 3-ft screens at about 69 to 72 ft bis), midway between the top of the
second clay unit and the top of the water table.
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• trailer-mounted SVE system (with extraction blower, air/fluid separation
[knockout tank], and vapor phase carbon), and a trailer-mounted air sparge system
(with air compressor and other appurtenances). A manifold extraction and air
injection system would allow phased operation of the SVE and sparge systems,
allowing 8 to 10 points being operated at any given time. Sequencing of SVE well
operation may also be used to allow their use as air entry wells.
• targeted soil excavation (about 900 cubic yards) near the oil/water separator, the
drum area, and near SE corner of building.
The decision to engage the thermal enhancement will be finalized in the RD and/or RA
phases, and may be based on one or more of the following reasons:
• Determination of the presence of mobile NAPL during RD or RA phases. Mobile
NAPL in soil will delay site remediation using SVE. Although NAPL has not been
observed and existing measurements of soil concentrations do not indicate the
presence of NAPL, uncertainty remains due to areas beneath the Walker building
remaining unprofiled and due to the large extent of the vadose zone.
• During RD or RA phases VOCs observed in soil are substantially higher than found
during the RI.
• Prolonged asymptotic concentrations observed in SVE vapors without groundwater
and indoor air cleanup levels being achieved.
Based on additional Site information collected during RD and/or RA phases, the thermal
enhancement, if engaged, may be employed to target a smaller area than currently
indicated. Similarly, active remediation of areas within the UZ may be curtailed if
additional data collected indicates that remediation is not necessary.
Groundwater monitoring will be conducted to evaluate the effects of the UZ actions and
contaminant flux reductions before determining the extent of SSZ remedial action that is
needed to meet RAOs.
12.2.2 Saturated Soil Zone
Alternative SSZ #5 (BiRD) is the selected remedy for the SSZ. This remedy uses an
injection well and recirculation well approach. A series of hexagonal recirculation cells
would be used to inject carbon substrate, sulfate, and iron solution to reduce residual
DNAPL, CVOCs adsorbed on saturated soil, and CVOCs dissolved in groundwater.
The BiRD technology relies principally on the in-situ production of iron sulfides for
chemical reduction and is designed to leverage any indigenous divalent metals that will
facilitate this process. Biodegradation is also available as an ancillary process due to the
reduced conditions induced by adding carbon substrate to lower the ORP.
The chemical reduction component of the remedy would have a faster kinetic rate for
degradation than the biodegradation component, although the synergistic effect of the two
technologies should be able to treat the soil/groundwater matrix within a 2- to 3-year
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timeframe. The persistence of the carbon substrate and iron sulfides produced from the
process will allow secondary contact with advecting COCs for an extended duration.
This remedy, as estimated in the FS, includes:
• installation of twenty-eight (28) 4-inch diameter injection wells with screen
intervals from 50 to 75 ft bis
• installation of thirteen 6-inch diameter recovery wells located at the foci of the
hexagonal grid approximately 30-feet from the injection wells. It is assumed that
any injection or recovery wells necessary under the onsite building would be
installed using angled drilling.
• use of groundwater from the recovery wells was assumed for chemical mixing for
the amendment solution addition. This water would require conditioning to lower
the ORP and adjust the pH.
• injection/recirculation period of 3 years is assumed with approximately 33,000
pounds of carbon substrate and 8,500 pounds of iron sulfate added during the
initial injection. Injection flowrates were estimated at between 5 to 15 gpm per
well.
• a secondary injection of amendments at 25% of the original dose during the
second year of operation. The recirculation system is estimated to operate for 3
years inclusive of 48 days of manned operation per year.
• use of an injection manifold for the recirculation wells and an equipment trailer
with air stripping, bag filtration, GAC, and supplemental water conditioning with
an oxygen scavenger for water treatment prior to reinjection.
• a 40-ft by 75-ft by 3-ft deep infiltration gallery is also to be installed to handle
supplemental discharge of water as needed.
• treatability testing would be required to analyze the Site mineralogy and select the
optimal amendments for the Site. A pH buffer would be required to offset the
production of acid from the reaction and to raise the natural pH to optimal levels
for chemical reduction and biodegradation. The remedy also assumes that
bioaugmentation with DHC other halorespiring bacteria would be required.
Groundwater monitoring will be conducted to evaluate the effects of the UZ and SSZ
actions and contaminant flux reductions before determining if implementation of DP #3
is still required.
12.2.3 Dilute Plume
Alternative DP #3 (EISB Passive Barrier Wells and a Horizontal Well) is the selected
remedy for the DP. Alternative DP #3 involves the use of EISB passive barriers
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consisting of injection wells across the DP coupled with a horizontal injection well for
the toe of the DP. The injection wells would be injected with emulsified oil substrate
supplemented with bioaugmentation and pH adjustment to accelerate biodegradation via
direct anaerobic reductive dechlorination of CVOCs in groundwater. The treatment
barriers would be emplaced solute barriers that would not alter or impede groundwater
transmissivity. This remedy, as estimated in the FS, includes
• installation of sixteen (16) 2-inch diameter wells with 28-ft spacing between the
wells for injection of emulsified oil substrate. The wells would be screened from
approximately 60 to 85 ft bis.
• installation of a 4-inch diameter 730-ft long horizontal (directionally drilled) well
(430-ft screen with 300 feet of riser at one end) would also be installed at
approximately 73 ft bis (mid-depth into the DP). A blind (no exit boring)
installation is presumed, but the well could be constructed with either approach. If
a directionally drilled well is deemed untenable due to property access or if
modeling indicates the vertical distribution may be insufficient, the DP #3 remedy
component can be altered to a series of approximately 23 injection wells along the
west and north edges of the Witt Property for an equivalent cost.
• injection of approximately 94,500 pounds of emulsified oil (or similar carbon
substrate) over an estimated injection period of 4 weeks.
• potable water from a hydrant was assumed for chemical mixing for the EISB
solution although recovered groundwater from a groundwater recovery well could
be used. This water would require conditioning to lower the ORP and adjust the
pH.
• treatability testing would be required to select the optimal EISB amendment for
the Site. A pH buffer would be required to offset the production of acid from the
reaction and to raise the natural pH to optimal levels for biodegradation. The
remedy also assumes that bioaugmentation with DHC other halorespiring bacteria
would be required.
12.2.4 Institutional Controls
Institutional Controls (ICs) will be implemented as part of the selected remedy. ICs are
non-engineering measures which include legal and administrative controls to affect
human activities in such a way as to prevent or reduce the potential for exposure to
contamination until cleanup goals are achieved. The purpose of the ICs is to impose on
the subject property "use" restrictions for the purpose of implementing, facilitating and
monitoring a remedial action to reduce exposure, thereby protecting human health and
the environment. Often ICs are more effective if they are layered or implemented in
series. Layering can involve using different types of ICs at the same time to help ensure
the protectiveness of the response action. ICs will be necessary at the Site to protect the
integrity of the groundwater remedy and to prevent unacceptable exposure to
contaminated groundwater and VOC vapors from soil gas as part of the selected remedy.
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Construction of a building or other structure over contaminated areas with VOC soil gas
may require mitigation systems or construction techniques to prevent VOC vapors
entering the structure. Similarly, continued operation of the existing sub-slab ventilation
system at the current Walker building will be required to reduce the potential for vapor
intrusion until cleanup goals are met. Some of the controls which will be implemented or
relied upon for the Site include, but are not limited to, the following:
• f Governmental controls, such as local zoning/land use ordinances arid local
permitting requirements to limit potential exposure of Site users to the COCs. The Site is
currently zoned general industrial and is anticipated to remain subject to this land use
classification. In addition, the Ground Water Quality Control Board for Shelby County
has established water-well regulations that include permit requirements. The regulations
include specific requirements for placement of water wells within a half-mile of a listed
Superfiind site. The Memphis Sand aquifer is the municipal water supply for the residents
near the Site.
• Proprietary controls, such as deed and land use restrictions (i.e., a restrictive
covenant executed by the landowner and recorded in Shelby County) will also be utilized
at the Site until cleanup goals are determined by EPA to have been met. Prohibited
activities under the restrictive covenant will include, but not be limited to the following:
the installation of groundwater wells at the Site; the use of groundwater at the Site; any
disturbance of engineered remedy components at the Site such as monitoring wells, vapor
intrusion mitigation/ventilation equipment, and the existing building slab.
12.2.5 Cost Estimate for the Selected Remedy
The estimated total net present worth cost for the Selected Remedy is $8,569,900 without
thermal enhancement or $11,747,400 with thermal enhancement. A summary of the costs
for each CMZ is listed below. Greater cost details can be found in Tables 27-29.
Selected Remedy Cost Estimate Summary
CMZ
Alternative #
Description
Cost without
Thermal
Enhancement
Cost with
Thermal
Enhancement
uz
UZ #2b
TE-SVE with Limited Air
Sparging
$3,083,800
$6,261,300
ssz
SSZ #5
BiRD (if needed)
$1,997,000
$1,997,000
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Selected Remedy Cost Estimate Summary
CMZ
Alternative #
Description
Cost without
Thermal
Enhancement
Cost with
Thermal
Enhancement
DP
DP #3
EISB Passive Barriers
with Horizontal Well (if
needed)
$2,449,700
$2,449,700
Site-Wide Costs (groundwater monitoring for. 10
years, five-year reviews, ICs, etc. for 30 years)
$1,039,400
$1,039,400
Total:
$8,569,900
$11,747,400
Notes: 5% discount rate. Estimated timeframes for each CMZ remedy: UZ - 5
years. SSZ - 3 years. DP - 20 years
The cost estimate is based on the available information regarding the anticipated scope of
the remedial action. Changes in the cost elements are likely to occur because of new
information and data collected during the RD phase. Major changes may be documented
in the form of a memorandum to the AR file, an Explanation of Significant Differences
(ESD), or a ROD Amendment. The projected cost is based on an order-of-magnitude
engineering cost estimate that is expected to be within +50 or -30 % of the actual project
cost. Costs are based on the conservative estimate of a 20-year timeframe until all
cleanup levels are met.
12.2.6 Recommended Phasing
A phased response action is recommended for the Site. The use of a phased approach
would allow EPA to mitigate more immediate site-specific threats while concurrently
collecting additional characterization data to determine the best method for attaining long
term objectives. The recommended phasing for the overall implementation of the selected
remedies is listed below. It is expected that some of these phases can proceed on
simultaneous tracks.
Phase
Task Description
Action
I
Oil/Water Separator Removal and Soil
Excavation
Removal of the oil/water separator, TCE
drum area, and visibly stained soil found in
these areas. Removal of ~900 bey of soil
located along the eastern side of the Walker
building to -10 ft bis with off-site disposal.
Collection of confirmation samples.
IIA
Implementation of SVE with Air Sparging
Adaptive phased installation of SVE wells,
air sparge wells, heater borings, etc.
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Phase
Task Description
Action
i.
Installation and operation of treatment
systems. Active remediation of portions of
the UZ may be curtailed if additional data
collected indicates that remediation is not
necessary. Groundwater and soil gas/indoor
air monitoring to assess COC flux reduction
and determine the extent of SSZ action.
IIB
Targeted Thermal Enhancement of SVE
System
Application of thermal enhancement as
needed
III
BiRD Remedy
If needed after implementation and evaluation
of Phase II, install BiRD wells, treatment
system and infiltration gallery. Groundwater
and soil gas/indoor air monitoring to assess
COC flux reduction and determine the need
for DP action.
IV
DP Remedy Evaluation
Evaluate groundwater monitoring results and
effects of UZ and SSZ remedial actions.
Determine if DP #3 remedy is still required
based on conditions resulting from UZ/SSZ
treatment.
A robust but phased remedy is recommended for the UZ (Alternative #2b). The UZ
remedy includes SVE with shallow air sparging as the primary remedial approach.
Thermal enhancement may be applied to accelerate or optimize the remedy based on Site
conditions observed during the RD and/or RA phase.
Groundwater monitoring will be conducted to evaluate the effects of the UZ treatment
and contaminant flux reductions before determining the timing and extent of subsequent
remedial action for the SSZ or DP.
12.2.7 Estimated Outcomes of the Selected Remedy
12.2.7.1 Available Use after Cleanup
The Site is currently in use for industrial/commercial purposes. Future land use of the Site
property is anticipated to continue to be industrial/commercial.
Groundwater in the Collierville area is currently used as a source of drinking water and
will continue to be used for drinking water in the future. The selected remedy for this Site
will greatly reduce the potential for contaminant migration towards the nearest water
supply wells which are found at Collierville's Wellfield #1. It may take about 20 years to
achieve groundwater cleanup levels.
12.2.7.2 Final Cleanup Levels
The final cleanup levels for soil, groundwater, and indoor air are. listed Tables 21 -23. It
may take between three to five years to achieve soil cleanup levels and about 20 years to
achieve groundwater cleanup levels.
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13.0 Statutory Determination
Based on the information currently available, EPA believes the response action selected
for each of the CMZs meets the threshold criteria and provides the best balance of
tradeoffs among the other alternatives with respect to the balancing and modifying
criteria. The EPA expects the selected remedy will satisfy the following statutory
requirements of CERCLA Section 121(b):
• Be protective of human health and the environment.
• Comply with ARARs;
• Be cost effective; and
• Use permanent solutions and alternative treatment technologies or resource recovery
technologies to the maximum extent practicable.
13.1 Protection of Human Health and the Environment
Protection of human health and the environment will be achieved through TE-SVE of
unsaturated subsurface soil contamination, sparging of upper saturated source
contamination, and the targeted removal of limited areas of shallow soil contamination.
The remedy would also reduce or eliminate contaminant VI and indoor air contaminants
in the Walker Building. If the BiRD or EISB barriers are deemed necessary it would
further add protection to human health and the environment through contaminant
destruction in suspected solvent source areas and the dilute plume.
13.2 Compliance with ARARs
Section 121(d) of CERCLA and NCP §300.430(f)(l)(ii)(B) require that remedial actions
at CERCLA sites attain legally applicable or relevant and appropriate federal and more
stringent state requirements, standards, criteria, and limitations which are collectively
referred to as "ARARs," unless such ARARs are waived under CERCLA section
121(d)(4). The selected remedy will comply with all ARARs and To Be Considered
guidance presented in Tables 24,25 and 26.
13.3 Cost Effectiveness
A cost-effective remedy in the Superfund program is one whose "costs are proportional
to its overall effectiveness" (NCP §300.430(f)(l)(ii)(D)). The "overall effectiveness" of a
remedial alternative is determined by evaluating the following three of the five balancing
criteria used in the detailed analysis of alternatives: (1) Long-term effectiveness and
permanence; (2) Reduction in toxicity, mobility and volume (TMV) through treatment;
and, (3) Short-term effectiveness. "Overall effectiveness is then compared to cost" to
determine whether a remedy is cost-effective (NCP §300.430(f)(l)(ii)(D)). The preamble
to the NCP states that decision makers should compare "the cost to effectiveness of each
alternative individually and the cost and effectiveness of alternatives in relation to one
another.
The EPA has determined that the selected remedy is cost-effective and that the overall
protectiveness of the remedy is proportional to the overall cost. Alternative UZ #2b is
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more expensive than the other UZ alternatives. However, the inclusion of the thermal
enhancement in UZ#2b provides the greatest likelihood of effectively achieving the soil
cleanup levels. The intended UZ approach is flexible and will help control costs because
additional data collected during the RD should help refine the extent of any needed
thermal enhancement. Alternative SSZ #5 is less expensive than some of the other SSZ
alternatives. SSZ#5 is expected to have a higher level of effectiveness due to its
groundwater recirculation features. Alternative DP #3 is somewhat more expensive than
the other active treatment alternative for the DP, but is expected to be more effective at
reaching cleanup goals in a shorter timeframe.
13.4 Use of Permanent Solutions and Alternative Treatment Technologies to the
Maximum Extent Practicable
The EPA has determined that the selected remedy represents the maximum extent to
which permanent solutions and treatment technologies can be utilized in a practicable .
manner at the Site. Of those alternatives that are protective of human health and the
environment and comply with ARARs, the EPA has determined that the selected remedy
provides the best balance of tradeoffs in terms of the five balancing criteria, while also
considering the statutory preference for treatment as a principal element, bias against off-
site treatment and disposal, and considering State and community acceptance.
The selected remedy is likely to have the greatest long-term effectiveness and
permanence because each selected CMZ component is an aggressive treatment that will
result in permanent reductions in contaminant concentrations. Significant effort will be
focused on treating source areas and thus reducing toxicity, mobility, or volume of the
contaminants. The selected remedy does not pose an undue short-term risk or
inconvenience compared to the other active alternatives. Implementability is not a
significant issue, except possibly regarding the installation of wells beneath buildings.
Angled borings can be used under the main building onsite, if needed. Angled borings
may result in somewhat less than ideal locations, but are not expected to significantly
impact the remedy performance. Installation of the horizontal injection well under the
adjacent Witt building is subject to property owner consent. The thermal enhancement for
the SVE in the unsaturated zone is costlier, but is more likely to be effective in achieving
cleanup levels, particularly in the clay and silt portions of the subsurface. The State has
stated a preference for aggressive treatment in the source areas with an expected benefit
of reducing the time and funds required to achieve cleanup levels in the downgradient
DP. The most decisive criteria in the selection decision were long term effectiveness and
permeance,-reducing toxicity, mobility, or volume of contaminants through treatment,
and State acceptance.
13.5 Preference for Treatment as a Principal Element
The NCP at 40 CFR §300.430(a)(I)(iii)(A) establishes an expectation that treatment will
be used to address PTW posed by a site wherever practicable. In general, the priority for
treatment for PTW is placed on source materials considered to be liquid, highly toxic or
highly mobile, which generally cannot be contained in a reliable manner or would present
a significant risk to human health or the environment should exposure occur.
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The contaminated soils under the main building and south of the main building at the Site
are considered to be principal threat wastes at this Site. Information about site operations
coupled with the documented groundwater impacts indicate that contaminants in soil are
present and are highly mobile. It is noted that soil data collected to date do not
quantitatively confirm high concentrations and that additional data will be collected
during the remedial design. The Selected Remedy includes aggressive treatment of the
contaminated soil that may be considered principal threat waste and therefore satisfies the
expectation in the NCP for treatment of the principal threat waste.
13.6 Five-Year Review Requirements
It is possible that this remedial action will ultimately allow for unlimited use and
unrestricted exposure after completion of the remedial action, but attainment of the RAOs
and cleanup levels will take longer than five years to achieve. A five-year review is
required pursuant to CERCLA § 121(c) and NCP §300.430(f)(5)(iii)(C). More
specifically, a policy five-year review should be conducted within five years of the date
of construction completion. EPA will conduct the FYR to ensure that the selected remedy
is, or will be, protective of human health and the environment. FYRs will continue until
levels that allow for unlimited use and unrestricted exposures are achieved.
13.7 Documentation of Significant Changes
Pursuant to CERCLA 117(b) and NCP §300.430(f)(3)(ii), the ROD must document any
significant changes made to the Preferred Alternative discussed in the Proposed Plan. The
Proposed Plan, which was released for public comment on May 31,2018, identified a
phased approach in implementation of UZ #2b, SSZ #5 and DP #2b as the site-wide
Preferred Remedy for the Walker site.
EPA reviewed comments submitted during the public comment period. It was determined
that no significant changes to the remedy, as originally identified in the Proposed Plan,
were necessary or appropriate based on public input. However, several minor changes
were made to the cleanup levels to ensure consistency with EPA policy and guidance.
The Proposed Plan included cleanup goals for onsite indoor air that were based on
potential future residential use of the building. However, current zoning and future land
use planning indicate that the reasonably anticipated future of the Site is commercial. The
indoor cleanup goals were revised to list only those contaminants that pose an
unacceptable risk for a future commercial/industrial occupant. The remaining indoor air
cleanup levels were revised from 42 ug/m3 to 180 ug/m3 for PCE and from 2.2 ug/m3 to
8.8 ug/m3 for TCE. The Proposed Plan included cleanup goals for two groundwater
contaminants that did not have associated MCLs and instead were based on a 10"4 risk
level. The cleanup levels for these two should have been based on a 10"6 risk level. The
groundwater cleanup level for 1,1-dichloroethane has been revised from 740 ug/1 to 7.4
ug/1. The groundwater cleanup level for 1,4-dioxane was been revised from 68 ug/1 to 2
ug/1 which is based on achievable detection limits (EPA CLP SOW for organics
(S0M02.4) October 2016). The cleanup level of 2 ug/1 corresponds to a risk level of
2.9x10-6.
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In addition, the following RAO that was listed in the Proposed Plan has been deleted:
Prevent human (onsite future residents and onsite future construction workers) exposure
to Site- related contaminated soil at concentrations above HHRA cancer risk levels or
HHRA non-cancer hazard levels. This RAO is not necessary because currently available
data do not indicate an unacceptable risk to future onsite residents from exposure to
accessible surface soils. The selected remedy will address more contaminated soils that
are likely to be present under portions of the building (and currently inaccessible) and
reduce potential risk in the unlikely event of future residential use of the Site. The hazard
quotient for the future construction worker based on exposure to soil is primarily
associated with manganese. However, as discussed in Section 7.1.4 of this ROD, given
the reported naturally occurring concentrations of manganese and similar site-specific
background levels, manganese is not considered to be a COC and soil is not considered to
be impacted by metals.
14.0 References
Black & Veatch, 2018a. Black & Veatch Special Projects Corp., Remedial
Investigation Report, Walker Machine Products, Inc., Collierville, Shelby County,
Tennessee, Revision 3. January 2018.
Black & Veatch, 2018b. Black & Veatch Special Projects Corp., Feasibility Study
Report, Walker Machine Products, Inc., Collierville, Shelby County, Tennessee,
Revision 1. February 2018.
Brahana, J.V., and Bradley, M.W., 1985, Delineation and description of the regional
aquifers of Tennessee—the Knox aquifer in Central and West Tennessee: U.S.
Geological Survey Water-Resources Investigations Report 83-4012, 32 p.
Brahana, J.V., and Broshears, R.E., 2001. Hydrogeology and ground-water flow in
the Memphis and Fort Pillow aquifers in the Memphis area, Tennessee, U.S.
Geological Survey Water Resource Investigation Report 89-4131, 56 p. 2001.
Collierville, 2016. Town of Collierville Division of Planning, April 2016 Zoning
Map, http://collierville.com/departments/development/planning/collierville-map-
gallery/zoning map.
Criner, J.H., and Parks, W.S., 1976. Historic water-level changes and pumpage from
the principal aquifers of the Memphis area, Tennessee, 1886-1975: U.S. Geological
Survey Water-Resources Investigations Report 76-67,45 p. 1976.
Doudrick, 2008. Kyle Wesley Doudrick. A Predictive Model of Ground-water Flow
and Contaminant Transport of Cr(VI) and TCE in Collierville, Tennessee, A Thesis
Presented for the Master of Science Degree, The University of Memphis, August
2008.
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EPA, 2013. U.S. Environmental Protection Agency, Hazard Ranking System (HRS)
Documentation Record, December 2013.
Etnier, D.A. and W.C. Starnes, 1993. The fishes of Tennessee. The University of
Tennessee Press, Knoxville, Tennessee, USA. 1993.
Graham, D.D., and Parks, W.S., 1986, Potential for leakage among principal
aquifers in the Memphis area, Tennessee: U.S. Geological Survey Water-Resources
Investigations Report 85-4295,46 p. 1986.
Parks, W.S., and Carmichael, J.K., 1990, Geology and ground-water resources of the
Fort Pillow Sand in western Tennessee: U.S. Geological Survey Water-Resources
Investigations Report 89-4120, p. 20.
Shelby County, 2016. Welcome to Shelby County Assessor of Property, Parcel ID:
C0245 00188,459 Washington Street, Collierville, Printed October 21,2016,
http://www.assessor.shelby.tn.us/Property
SearchDetail.aspx?id=C0245%20%20%2000188.
TDEC, 2008. Pre-Comprehensive Environmental Response, Compensation, and
Liability Information System (CERLIS) Screening Assessment Report, Walker
Machinery, Revision 1. Prepared for EPA, June 25, 2008.
TDEC, 2010. Site Reassessment Report. Walker Machine Products. Prepared for
EPA. June 16,2010.
TDEC, 2011. Site Investigation Report, Walker Machine Products. Prepared for
EPA. August 22,2011.
TDEC, 2012 Tennessee Department of Environment and Conservation. Expanded
Site Investigation Report, Walker Machine Products. Prepared for EPA. September
15,2012.
TDEC, 2013. Tennessee Department of Environmental Conservation Underground
Storage Tank Risk Based Cleanup Levels for Domestic Water Supply Use, 2013.
TDEC, No date. Site Inspection Report. Witt International, Inc. Prepared for EPA.
Not Dated.
TDH, 1987. Tennessee Department of Health and Environment. Office
Correspondence. Subject: Notice of Violation, September 8,1987, Walker Machine
Products, Lie, TND982115016. From: Paul Patterson. To: J. Tom Tiesler. February
29, 1987.
62
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TDOR, 2012. Project Note to File. Subject: Meeting with Mr. Harold Langley.
September 10, 2012, 1 Page.
Tetra Tech, 2012a. Tetra Tech, Project Note to File. Subject: Missing Confining
Unit at Walker Machine. November 26, 2012.
Tetra Tech, 2012b. Tetra Tech, Membrane Interface Probe (MIP) and Direct Push
Technology (DPT) Investigation. November 20,2012.
USGS, 2006. U.S. Geological Survey and U.S. Department of the Interior,
Description, Properties, and Degradation of Selected Volatile Organic Compounds
Detected in Ground Water-A Review of Selected Literature, Open-File Report 2006-
1337,2006.
Van Arsdale, R., and Cox, R., 2007, The Mississippi's Curious Origins. Scientific
Amierican, January. 2007, p. 33-39.
Walker Machine Products, Inc, 1987. Letter with Attachment. From: Harold D.
Walker, Jr., President. To: Tom Yates, Tennessee Department of Health and
Environment. Attachment: Hazardous Waste Notification. September 29, 1987.
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PART 3: RESPONSIVENESS SUMMARY
This is Responsiveness Summary responds to comments that the public has made
regarding the EPA's Proposed Plan for the cleanup of hazardous substance contamination
at the Walker Machine Superfiind Site.
A Responsiveness Summary serves two functions: first, it provides the decision maker
with information about the views of the public, government agencies, and potentially
responsible parties (PRPs) regarding the proposed remedial action and other alternatives;
and second, it documents the way in which public comments have been considered
during the decision-making process and provide answers to significant comments.
Under the EPA policy, responsiveness summaries are typically divided into two parts.
The first part is a summary of general stakeholder issues and concerns, and it will
expressly acknowledge and respond to those issues and concerns raised by major
stakeholders (e.g., community groups, support agencies, businesses, municipalities,
PRPs). The second part is a comprehensive response to all specific comments. It is
comprised mostly of specific legal and technical questions, and, if necessary, will
elaborate with technical detail on answers covered in the first part of the responsiveness
summary.
No verbal or written comments were submitted to EPA during the comment period. Two
citizens attended the public meeting held on June 14,2018. A few questions were asked
during the public meeting and the responses are noted in the transcript of the public
meeting (Appendix A). Those questions related to the expected timeframe for the three
phases of the cleanup, control measures for vapors from the SVE system, and expected
byproducts from the insitu treatment of groundwater. TDEC.also attended the public
meeting and expressed support for the preferred alternative with an emphasis on
performing the work in phases.
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Record of Decision
Table 1. Occurrence, Distribution, and Selection of Chemicals of Potential Concern in Soil
(2018 Human Health Risk Assessment)
Chemical
of
Concern
Exposure
Unit
Detection
Frequency
Min
Cone.1
(mg/kg)
Max
Cone.1
(mg/kg)
Location
of Max
Cone.
Mean
Cone,
(mg/kg)
95%
UCL of
Mean
(mg/kg)
Exposure
Point
Cone,
(mg/kg)
Background
Cone,
(mg/kg)
Background
Location
Screening
Toxicity
Value
(mg/kg)
Aluminum
On-site
Surface
12/12
3,300
11,000
WM218
6,805
7,913
7,913
4,100
WM216
7,700
On-site
Subsurface
26/26
1700
14000
WM223
7,854
8,796
8,796
5,100
WM216
Arsenic
On-site
Surface
12/12
2.7
14
WM219
6.782
8.402
8.402
4.1
WM216
0.68
On-site
Subsurface
26/26
0.89
9.3
WM228
5.454
6.215
6.215
3.1
WM216
Cobalt
On-site
Surface
12/12
4.8
27
WM201
9:114
12.73
12.73
6.0
WM216
2.3
On-site .
Subsurface
26/26
0.18
18
WM228
6.776
9.987
9.987
5.9
WM216
Manganese
On-site
Surface
12/12
240
1,600
WM201
565.5
775.3
775.3
420
WM216
180
On-site
Subsurface
26/26
4.5
980
WM216
377.6
459.2
459.2
980
WM216
Nickel
On-site .
Subsurface
26/26
1
720
WM228
38.98
168.1
168.1
5.7
WM216
150
Notes: 1
1 = Minimum/maximum detected concentration in soil
NA = None available
UCL = Upper Confidence Limit
me/ke - Milligrams per kilogram Source: Human Health Risk Assessment (Black & Veatch. 2018)
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Table 2. Occurrence, Distribution, and Selection of Chemicals of Potential Concern in Groundwater
(2018 Human Health Risk Assessment)
Chemical
of Concern
Exposure
Unit
Detection
Frequency
Min
Cone.1
(Mg/L)
Max
Cone.1
Location
of Max
Cone.
Mean
Cone.
(refL)
95%
UCLof
Mean
(me/L)
Exposure
Point
Cone.
(veJU
Background
Cone.
(Hg/L)
Background
Location
Screening
Toxicity
Value
(MJi/L)
1,4-Dioxane
On-site
11/24
1.7 J
31
WM03
14.12
21.94
21.94
Non-detect
WM01
0.46
Off-site
2/19
2.53 J
2.8
W102
2.665
NC
2.665
Bis(2-
ethylhexyl)Phthalate
On-site
1/23
150
150
WM03
150
NC
150
Non-detect
WM01
5.6
Off-site
1/18
5.9
5.9
WM108
5.9
NC
5.9
1,1,2-T richloroethane
On-site
5/47
0.26 J
2.1 J
WM03
1.725
NC
2.05
Non-detect
WM0I
0.041
Off-site
2/48
0.47 J
0.79 J
WI02
0.63
NC
0.79
1,1 -Dichloroethane
On-site
26/47
4.6 J
120
WM03
85.89
101.4
101.4
Non-detect
WM0I
2.8
Off-site
20/48
0.31 J
86
WI02
53
65.55
65.55
1,2-Dichloroethane
On-site
2/47
0.77
1.1 J
WM05
0.935
NC
1.1
Non-detect
WM01
0.17
Off-site
2/48
0.81
2.7 J
WI02
1.755
NC
2.7
Benzene
Off-site
3/48
0.1 J
1.5
WM19
0.59
1.92
. 1.5
Non-detect
WM01
0.46
Bromodichloromethane
On-site
5/47
0.64
1.8
WM02
1.038
1.651
1.651
Non-detect
WM01
0.13
Off-site
2/48
0.61
. 4:8
WM105
2.705
NC
4.8
Carbon Tetrachloride
On-site
1/47
12
12
WM03
12
NC
12
Non-detect
WM01
0.46
cis-1,2-Dichloroethene
On-site
27/47
1.1 J
180 J
WM03
149.4
158
158
Non-detect
WM01
3.6
Dibromochloromethane
On-site
5/47
1
3.1
WM02
1.663
2.801
2.801
Non-detect
WM01
0.87
Off-site
1/48
3.4
3.4
WM105
3.4
NC
3.4
Methylene Chloride
On-site
1/45
23.3 J
23.3 J
WM05
23.3
NC
23.3
Non-detect
WM01
11
Tetrachloroethene
On-site
30/47
0.2 J
2,450
WM05
1,884
2,217
2,217
Non-detect
WM01
4.1
Off-site
34/48
0.15 J
1,000
WI02
421.9
564.4
564.4 ¦
trans-1,2-Dichloroethene
On-site
7/47
0.64
54 J
WM05
54
NC
54
Non-detect
WM01
36
Trichloroethene
On-site
29/47
0.11 J
180
WM03
138.7
150.6
150.6
Non-detect
WM01
0.28
Off-site
23/48
0.99 J
73
W102
30.49
61.33
61.33
Vinyl Chloride
On-site
1/47
0.32 J
0.32 J
WM03
0.32
NC
0.32
Non-detect
WM01
0.019
Aluminum
Off-site
9/19
100
4,700
WI01
1,703
2,9%
2,996
Non-detect
WM01
2,000
Arsenic
On-site
2/23
0.24 J
1.4 J
WM106
0.82
NC
1.4
Non-detect
WM01
0.052
Off-site
5/19
0.15 J
3.6 J
WI01
1.783
3.701
3.6
Beryllium
Off-site
2/19
1.7
9.6
WM108
5.65
NC
9.6
Non-detect
WM01
3
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Table 2. Occurrence, Distribution, and Selection of Chemicals of Potential Concern in Groundwater
(2018 Human Health Risk Assessment)
Chemical
of Concern
Exposure"
Unit
Detection
Frequency
Min
Cone.1
(Mg/L)
Max
Cone.1
(Mg/L)
Location
of Max
Cone.
Mean
Cone.
(pg/L)
95%
UCL of
Mean
(ue/L)
Exposure
Point
Cone.
(pg/L)
Background
Cone.
(Mg/L)
Background
Location
Screening
Toxicity
Value
(lig/L)
Cobalt
On-site
5/23
4 J
12
WM111
7.25
11.55
11.55
Non-detect
WM01
. 0.6
Off-site
5/19
6.2 J
61
WI01
23.7
54.06
54.06
Copper
Off-site
5/19
0.8 J
1,000 J
WM109
307.7
854.5
854.5
Non-detect
WM01
80
Iron
Off-site
13/19
140
36,000
W101
5,177
34,244
34,244
190
WM01
1,400
Manganese
On-site
13/23
6.9
850
WM106
226.5
679.1
679.1
Non-detect
WM0I
43
Off-site
12/19
7.4
720
WM105
161.2
434.7
434.7
Nickel
Off-site
7/19
2.1
2,900
WI01
509.1
9,479
2,900
Non-detect
WM0I
39
Notes:
1 = Minimum/maximum detected concentration in soil
NA = None available
NC = Not calculated due to small sample size
UCL = Upper Confidence Limit
J = Estimated concentration
me/kg = Milligrams per kilogram
Source: Human Health Risk Assessment (Black & Veatch. 2018)
Page 3 of 49
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Walker Machine Products
Record of Decision
Table 3. Occurrence, Distribution, and Selection of [Chemicals of Potential Concern in Sediment
(2018 Human Health Risk Assessment)
Chemical
of Concern
Eiposure
Area
Detection
Frequency
Min
Cone.'
(Mg/kg)
Max
Cone.'
Location
of Max
Cone.
Mean
Cone.
(Hg/kg)
95%
UCLof
Mean
(ng/kg)
Exposure
Point Cone.
(MS/kg)
Background
Cone.
(Mg/fcg)
Screening
Toxicity
Value
(Mg/kg)
BaPTEQ
On-site
3/3
193.9
2,155
WM302
1,092
2,763
2,155
180-270
16
Arsenic
On-site
3/3
1,200
4,800
WM301
2,933
5,974
4,800
1,800-2,000
680
Notes:
BaP TEQ - Benzo(a)pyrene Toxicity Equivalent
1 - Minimum/maximum detected concentration in sediment
Mg/kg - micrograms per kilogram Source: Human Health Risk Assessment (Black & Veatch, 2018)
Commented [NH1]: Seems like these are CO PCs and not COCs.
Can you remove the table or relabel it?
Page 4 of 49
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Walker Machine Products
Record of Decision
Table 4. Occurrence, Distribution, and Selection of Chemicals of Potential Concern in Indoor Air
(2018 Human Health Risk Assessment)
Chemical
of Concern .
Exposure
Unit
Detection
Frequency
Min
Cone.1
(|ig/m')
Max
Cone.'
(Hg/m3)
Location
of Max
Cone.
Mean
Cone.
(fig/m1)
95%
UCL of
Mean
(ne/m3)
Exposure
Point
Cone.
(ue/m1)
Background
Cone.
(fig/m1)
Screening
Toxicity
Value
(MC/m3)
1,2,4-
Trimethylbenzene
On-site
17/28
0.9 J
41
• SG402
6.125
14.07
14.07
1
u>
bo
0.73
1,2-Dichloroethane
On-site
1/28
0.69
0.69
SG404
0.69
NC
0.69
ND
0.11
Off-site
1/4
0.153
0.153
WISG500
0.08325
NC
0.153
1,4-Dioxane
Off-site
3/4
0.168 J
2.64
W1SG500
0.819
2.34
2.34
ND
0.56
Benzene
On-site
23/28
0.34 J
7.5
SG404
1.914
3.522
3.522
0.35-4.1
0.36
Carbon Tetrachloride
On-site
15/28
0.44 J
0.62
SG402
0.539
0.565
0.565
0.47-0.52
0.47
Ethylbenzene
On-site
27/28
0.9 J
31
SG400
4.89
6.701
6.701
0
1
vo
1.1
Naphthalene
On-site
28/28
0.094
6.5
SG402
1.482
2.064
2.064
0.061 - 1.4
0.083
Styrene
Off-site
4/4
0.123 J
213
WISG500
54.3
179
179
ND
100
Tetrachloroethene
On-site
22/28
0.51 J
320
SG400
14.48
64.29
64.29
0.65 - 7.8
4.2
Trichloroethene
On-site
25/27
0.43 J
340
SG402
18.87
71.67
71.67
0.43-1.3
0.21
Total Xylenes
On-site
27/28
3.34 J
132
SG400
23.74
35.79
35.79
2.23-19
10
Notes:
1Minimum/maximum detected concentration in soil
NA = None available
NC = Not calculated due to small sample size
UCL = Upper Confidence Limit
J = Estimated concentration
mg/kg - Milligrams per kilogram Source: Human Health Risk Assessment (Black & Veatch. 2018)
Page 5 of 49
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Walker Machine Products
Record of Decision
Table 5. Risk Characterization Summary - Carcinogens in Surface Soil (Future Resident)
(2018 Human Health Risk Assessment)
Scenario Timeframe: Future
Receptor Population: Resident
Receptor Age: Lifetime
Carcinogenic Risks
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Ingestion
Inhalation
Dermal
Exposure
Routes Total
Arsenic
I.1E-05
9.5E-09
1.7E-06
I.3E-05
Soil
Surface Soil
On-site
Cobalt
NC
3.0E-08
NC
3.0E-08
Soil Risk Total =
1.3E-05
Notes:
NC - Not calculated (carcinogenic toxicity criteria not available for exposure pathway)
Source: Human Health Risk Assessment (Black & Veatch, 2018)
Page 6 of 49
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Walker Machine Products
Record of Decision
Table 6. Risk Characterization Summary - Non-carcinogens in Surface Soil (Future Resident)
(2018 Human Health Risk Assessment)
Scenario Timeframe: Future
Receptor Population: Resident
Receptor Aee: Lifetime
Non-cancer Hazard Index
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Ineestion
Inhalation
Dermal
Exposure
Routes Total
Arsenic
0.07
0.0004
0.01
0.08
Cobalt
0.2
0.001
NE
0.2
ManRanese
0.1
¦ 0.01
NE
0.1
Soil
Surface Soil
On-site
Soil HI Total =
0.3
Total Skin
- Vascular HI =
0.08
Total Thyroid HI =
0.2
Total CNS HI =
0.1
Notes:
CNS = Central Nervous System
HI = Hazard Index
NE = Pathway not evaluated.
Source: Human Health Risk Assessment (Black & Veatch, 2018).
Page 7 of 49
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Walker Machine Products
Record of Decision
Table 7. Risk Characterization Summary - Carcinogens in Soil (Future Construction Worker)
(2018 Human Health Risk Assessment)
Scenario Timeframe: Future
Receptor Population: Construction Worker
Receptor Age: Adult
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Carcinogenic Risks
Ingestion
Inhalation
Dermal
Exposure
Routes Total
Soil
Surface Soil
On-site
Arsenic
2.0E-07
1.9E-07
6.9E-08
4.5E-07
Cobalt
NC
5.9E-07
NC
5.9E-07
Surface Soil Risk Total =
1.0E-06
Subsurface Soil
On-site
Arsenic
1.5E-07
1.4E-07
5.1E-08
3.4E-07
Cobalt
NC
4.6E-07
NC
4.6E-07
Subsurface Soil Risk Total =
. 8.0E-07
Soil Risk Total =
2E-06
Notes:
NC - Not calculated (carcinogenic toxicity criteria not available for exposure pathway)
Source: Human Health Risk Assessment (Black & Veatch, 2018)
Page 8 of 49
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Walker Machine Products
Record of Decision
Table 8. Risk Characterization Summary - Non-carcinogens in Soil (Future Construction Worker)
(2018 Human Health Risk Assessment)
Scenario Timeframe: Future
Receptor Population: Construction Worker
Receptor Age: Adult
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Non-cancer Hazard Index
Ineestion
Inhalation
Dermal
Exposure
Routes Total
Soil
Surface Soil
On-site
Aluminum
0.01
0.6
NE
0.6
Arsenic
0.002
0.2
0.0006
0.2
Cobalt
0.008
0.2
NE
0.2
Manganese
0.06
6
NE
6
Surface Soil HI Total =
7
Subsurface
Soil
Aluminum
0.02
0.6
NE
0.7
Arsenic
0.001
0.1
0.0005
0.2
Cobalt
0.006
0.2
NE
0.2
Manganese
0.04
3
NE
3
Nickel
0.02.
• 0.3
NE
0.3
Subsurface Soil HI Total =
5
Soil Total HI =
11
Total CNS HI =
11
Total Developmental HI =
0.3
Total Respiratory System HI =
1
Notes:
CNS = Central Nervous System
HI - Hazard Index
NE = pathway not evaluated
Source: Human Health Risk Assessment (Black & Veatch, 2018).
Page 9 of 49
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Walker Machine Products
Record of Decision
Table 9. Risk Characterization Summary - Carcinogens in Groundwater Future Resident (2018 Human Health Risk Assessment)
Scenario Timeframe: Future
Receptor Population: Resident
Receptor Aee: Lifetime
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Carcinogenic Risks
Ingestion
Inhalation
Dermal
. Exposure
Routes Total
Groundwater
Groundwater
On-site
1,4-Dioxane
2.8E-05
3.9E-06
. 1.0E-07
3E-05
Bis(2-ethylhexyl) Phthalate
2.7E-05
NE
NE
3E-05
1.1,2-Trichloroethane
1.5E-06
1.2E-06
1.1E-07
3E-06
1,1-Dichloroethane
7.4E-06
5.8E-06
5.8E-07
1E-05
1,2-Dichloroethane
1.3E-06
1.0E-06
6.2E-08
2E-06
Bromodichloromethane
1.3E-06
2.2E-06
9.IE-08
4E-06
Carbon Tetrachloride
1.1E-05
2.6E-06
2.9E-06
2E-05
Dibromochloromethane
3.0E-06
2.7E-06
2.0E-07
6E-06
Methylene Chloride
1.5E-06
1.7E-08
5.1E-08
2E-06
Tetrachloroethene
6.0E-05
2.1E-05
3.5E-05
1E-04
Trichloroethene
I.2E-04
2.7E-05
1.9E-05
2E-04
Vinyl Chloride
5.8E-06
I.0E-07
4.5E-07
6E-06
Arsenic
2.7E-05
NE
1.5EW
3E-05
On-Site Groundwater Risk Total =
4E-04
Off-site
1,4-Dioxane
3.4E-06
4.7E-07
1.2E-08
4E-06
Bis(2-ethylhexyl) Phthalate
1.1E-06
NE
NE
1E-06
1,1,2-T richloroethane
5.8E-07
4.5E-07
4.1E-08
IE-06
1,1-Dichloroethane
4.8E-06
3.7E-06
3.7E-07
9E-06
1,2-Dichloroethane
3.2E-06
2.5E-06
1.5E-07
6E-06
Benzene
1.1E-06
4.2E-07
1.6E-07
2E-06
Bromodichloromethane
3.8E-06
6.3E-06
2.7E-07
1E-05
Dibromochloromethane
3.7E-06
3.3E-06
2.5E-07
7E-06
Tetrachloroethene
I.5E-05
5.2E-06
9.0E-06
3E-05
Trichloroethene
4.7E-05
1.1E-05
7.5E-06
7E-05
Arsenic
6.9E-05
NE
3.8E-07
7E-05
Off-Site Groundwater Risk Total =
2E-04
Notes:
NE = pathway not evaluated
Source: Human Health Risk Assessment (Black & Veatch, 2018)
Page 10 of 49
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Walker Machine Products
Record of Decision
Table 10. Risk Characterization Summary - Non-carcinogens in Groundwater (Future Resilient)
(2018 Human Health Risk Assessment)
Scenario Timeframe: Future
Receptor Population: Resident
Receptor Aee: Lifetime
Non-cancer Hazard Index
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Ingestion
Inhalation
Dermal
Exposure
Routes Total
cis-1,2-Dichloroethene
3
NC
0.3
3
Tetrachloroethene
13
5
8
26
trans-1,2-Dichloroethene
0.09
0.09
.008
0.2
Trichloroethene
10
7
2
19
Cobalt
1
NE
.003
1
On-site
Manganese -
1
NE
0.1
1
On-Site Groundwater Total HI =
51
Total CNS HI =
27
Total Developmental System HI =
19
Total Thyroid HI =
1
Total Kidney HI =
3
Total Immune System HI =
19
Tetrachloroethene
3
1
2
7
Groundwater
Groundwater
Trichloroethene
4
3
0.7
8
Aluminum
0.1
. NE
0.0006
0.1
Beryllium
0.2
NE
0.1
0.3
Cobalt
6
NE
0.01
6
Copper
0.7
NE
0.004
0.7
Iron
2
NE
0.009
2
Off-site
Manganese
0.6
NE
0.08
0.7
Nickel
5
NE
0.1
5
Off-Site Groundwater Total HI =
29
Total CNS HI =
7
Total Developmental System HI =
8
Total Thyroid HI =
6
Total GI Tract HI =
3
Total Immune System HI =
8
Total Body Weight HI =
5
Notes:
CNS = Central Nervous System
HI = Hazard Index
NC = Not calculated (toxicity criteria not available for exposure pathway)
NE = Pathway not evaluated Source: Human Health Risk Assessment (Black & Veatch, 2018).
Page 11 of 49
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Walker Machine Products
Record of Decision
Table 11. Risk Characterization Summary - Carcinogens in Groundwater (Future Industrial/Commercial Worker)
(2018 Human Health Risk Assessment)
Scenario Timeframe: Future
Receptor Population: Industrial/Commercial Worker
Receptor Age: Adult
Carcinogenic Risks
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Ingestion
Inhalation
Dermal
Exposure
Routes Total
On-site
None
Groundwater
Groundwater
On-Site Groundwater Risk Total —
Off-site
None I I I
OfT-Site Groundwater Risk Total =
Notes:
Source: Human Health Risk Assessment (Black & Veatch, 2018)
Page 12 of 49
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Walker Machine Products
Record of Decision
Table 12. Risk Characterization Summary - Non-carcinogens in Groundwater (Future Industrial/Commercial Worker)
(2018 Human Health Risk Assessment) --
Scenario Timeframe: Future
Receptor Population: Industrial/Commercial Worker
Receptor Aee: Adult
Non-cancer Hazard Index
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Ingestion
Inhalation
Dermal
Exposure
Routes Total
Tetrachloroethene
3
NE
NE
3
Trichloroethene
3
NE
NE
3
Manganese
0.2
NE
NE
0.2
On-site
On-Site Groundwater Total HI =
6
Groundwater
Groundwater
Total CNS HI =
3
Total Developmental System HI =
3
Total Immune System HI =
3
Cobalt
2
. NE
NE
2
Off-site
Off-Site Groundwater Total HI =
2
Total Thyroid HI =
2
Notes:
CNS = Central Nervous System
HI = Hazard Index
NE = Pathway not evaluated
Source: Human Health Risk Assessment (Black & Veatch, 2018).
Page 13 of 49
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Walker Machine Products
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Tabic 13. Risk Characterization Summary - Carcinogens in Groundwater Future (Construction Worker)
(2018 Human Health Risk Assessment)
Scenario Timeframe: Future
Receptor Population: Construction Worker
Receptor Age: Adult
Carcinogenic Risks
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Ingestion
Inhalation
Dermal
Exposure
Routes Total
On-site
None
Groundwater
Groundwater
On-Site Groundwater Risk Total =
None I I I
Off-site
Off-Site Groundwater Risk Total =
Notes:
Source: Human Health Risk Assessment (Black & Veatch, 2018)
Page 14 of 49
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Walker Machine Products
Record of Decision
Table 14. Risk Characterization Summary - Non-Carcinogens in Groundwater (Future Construction Worker)
(2018 Human Health Risk Assessment)
Scenario Timeframe: Future
Receptor Population: Construction Worker
Receptor Aee: Adult
Non-cancer Hazard Index
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Ingestion
Inhalation
Dermal
Exposure
Routes Total
Tetrachloroethene
2
NE
NE
2
Trichloroethene
3
NE
NE
3
Manganese
0.2
NE
NE
0.2
On-site
On-Site Groundwater Total HI =
5
Groundwater
Groundwater
Total CNS HI =
2
Total Developmental System HI =
3
Total Immune System HI =
3
Off-site
None I I I
Off-Site Groundwater Total HI =
Notes:
CNS .= Central Nervous System
HI = Hazard Index
NE = Pathway not evaluated
Source: Human Health Risk Assessment (Black & Veatch, 2018).
Page 15 of 49
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Walker Machine Products
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Table 15. Risk Characterization Summary - Carcinogens in Sediment (Future Resident)
(2018 Human Health Risk Assessment)
Scenario Timeframe: Future
Receptor Population: Resident
Receptor Age: Lifetime
Carcinogenic Risks
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Ingestion
Inhalation
Dermal
Exposure
Routes Total
BaP TEQ
2.0E-06
NE
7.1E-07
2.7E-06
Sediment
Sediment
On-site
Arsenic
9.2E-07
NE
1.4E-07
1.1E-06
Sediment Risk Total =
4E-06
Notes:
BaP TEQ = Benzo(a)pyrcne Toxicity Equivalent
NE = Pathway not evaluated
Source: Human Health Risk Assessment (Black & Veatch, 2018)
Page 16 of 49
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Walker Machine Products
Record of Decision
Table 16. Risk Characterization Summary - Non-carcinogens in Sediment (Future Resident)
(2018 Human Health Risk Assessment)
Scenario Timeframe: Future
Receptor Population: Resident
Receptor Age: Lifetime
Non-cancer Hazard Index
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Ingestion
Inhalation
Dermal
Exposure
Routes Total
Sediment
Sediment
On-site
None
Sediment HI Total =
Notes:
HI = Hazard Index
Source: Human Health Risk Assessment (Black & Veatch, 2018).
Page 17 of 49
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Walker Machine Products
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Table 17. Risk Characterization Summary - Carcinogens in Indoor Air (Future Resident)
(2018 Human Health Risk Assessment)
Scenario Timeframe: Future
Receptor Population: Resident
Receptor Age: Lifetime
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Carcinogenic Risks
Ingestion
Inhalation
Dermal
Exposure
Routes Total
Indoor Air
Indoor Air
On-site
1,2-Dichloroethane
NA
6.4E-06
NA
6E-06
Benzene
NA
9.8E-06
NA
1E-05
Carbon Tetrachloride
NA
1.2E-06
NA
1E-06
Ethvlbenzene
NA
6.0E-06
NA
6E-06
Naphthalene
NA
2.5E-05
NA
2E-05
Tetrachloroethene
NA
6.0E-06
NA
6E-06
Trichloroethene
NA
1.3E-04
NA
1E-04
On-Site Indoor Air Risk Total =
2E-04
Off-site
1,4-Dioxane
NA
4.2E-06
NA
4E-06
1,2-Dichloroethane
NA
1.4E-06
NA
1E-06
Off-Site Indoor Air Risk Total =
6E-06
Notes:
NA = Pathway not applicable
Source: Human Health Risk Assessment (Black & Vcatch, 2018)
Page 18 of 49
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Walker Machine Products
- Record of Decision
Table 18. Risk Characterization Summary - Non-carcinogens in Indoor Air (Future Resident)
(2018 Human Health Risk Assessment)
Scenario Timeframe: Future
Receptor Population: Resident
Receptor Aee: Lifetime
Non-cancer Hazard Index
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Ingestion
Inhalation
Dermal
Exposure
Routes Total
1,2.4-Trimethvlbenzene
NA
2
NA
2
Benzene
NA
0.1
. NA
0.1
Naphthalene
NA
0.7
NA
0.7
Tetrachloroethene
NA
2
NA
2
Trichloroethene
NA
34
NA
34
On-site
Total Xylenes
NA
0.3
NA
0.3
On-Site Indoor Air Total HI =
39
Indoor Air
Indoor Air
Total CNS HI =
2
Total Developmental System HI =
34
Total Blood HI =
2
Total Respiratory System HI =
0.7
Total Immune System HI =
34
Styrene
NA
0.2
NA
0.2
Off-site
Off-Site Indoor Air Total HI =
0.2
Total CNS HI =
0.2
Notes:
CNS = Central Nervous System
HI = Hazard Index
NA = Pathway not applicable
Source: Human Health Risk Assessment (Black & Veatch, 2018).
Page 19 of 49
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Walker Machine Products
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Tabic 19. Risk Characterization Summary - Carcinogens in Indoor Air (Current/Future Industrial/Commercial Worker)
(2018 Human Health Risk Assessment)
Scenario Timeframe: Current/Future
Receptor Population: Industrial/Commercial Worker
Receptor Age: Adult
Carcinogenic Risks
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Ingestion
Inhalation
Dermal
Exposure
Routes Total
On-site
None
Indoor Air
Indoor Air
On-Site Indoor Air Risk Total =
Off-site
None I I I
Off-Site Indoor Air Risk Total =
Notes:
Source: Human Health Risk Assessment (Black & Veatch. 2018)
Page 20 of 49
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Walker Machine Products
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Table 20. Risk Characterization Summary - Non-carcinogens in Indoor Air (Current/Future Industrial/Commercial Worker)
(2018 Human Health Risk Assessment) .
Scenario Timeframe: Future
Receptor Population: Resident
Receptor Age: Lifetime
Non-cancer Hazard Index
Medium
Exposure
Medium
Exposure
Point
Chemical of
Concern
Ingestion
Inhalation
Dermal
Exposure
Routes Total
Tetrachloroethene
NA
0.4
NA
0.4
Trichloroethene
NA
8
NA
8
On-site
On-Site Indoor Air Total HI =
9
Indoor Air
Indoor Air
Total CNS HI =
0.4
Total Developmental System HI =
8
Total Immune System HI =
8
Off-site
None 1 1 1
Off-Site Indoor Air Total HI =
Notes:
CNS = Central Nervous System
HI = Hazard Index
NA = Pathway not applicable
Source: Human Health Risk Assessment (Black & Veatch, 2018).
Page 21 of 49
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Walker Machine Products
Record of Decision
Table 21. Cleanup levels for Chemicals of Concern in Subsurface Soil
Chemical of Concern
Unit
RGO
Basis
1,1-Dichloroethene
ug/kg
120
Soil levels protective of groundwater (for teachability from
soil to GW).
cis-1,2-Dichloroethene
ug/kg
833
Tetrachloroethene
ug/kg
126
Trichloroethene
ug/kg
126
Notes:
ug/kg - microgram per kilogram
RGO - Remedial Goal Option
Page 22 of 49
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Walker Machine Products
Record of Decision
Table 22. Cleanup levels for Chemicals of Concern in Groundwater
Chemicals of Concern
Unit
RGO
Basis
1,4-Dioxane
2.0
Protective based on ingestion of groundwater1
1,1-Dichloroethane
Hg/1
7.4
Protective based on ingestion of groundwater2
1,1-Dichloroethene
Mg/1
7
Protective for groundwater quality'
Carbon Tetrachloride
Hg/1
5
Protective for groundwater quality3
cis-1,2-Dichloroethene
Hg/1
70
Protective for groundwater quality3
Methylene Chloride
Hg/l
5
Protective for groundwater quality3
Tetrachloroethene
Hg/I
5
Protective for groundwater quality3
Trichloroethene
Hg/1
5
Protective for groundwater quality3
Vinyl Chloride
l»g/l
2
Protective for groundwater quality3
Notes:
ug/1 - microgram per liter
RGO - Remedial Goal Option
1 - based on current EPA contract required detection (EPA CLP SOW for organics (S0M02.4) October 2016). Corresponds to a risk level of 2.9X10"6
2 - (lO^risk level)
3 - based on Safe Drinking Water Act National Primary DrinkinR Water Regulation Maximum Contaminant Levels (MCLs)
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Table 23. Cleanup levels for Chemicals of Concern in Indoor Air
Chemical of Concern
Unit
RGO
Basi9
Tetrachloroethene
Ug/m3
180
Protective for current/future commercial use1
Trichloroethene
Hg/m3
8.8
Notes:
1: based on hazard quotient=l
ug/m3 - microgram per cubic meter
RGO - Remedial Goal Option
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Table 24. Potential Chemical-specific ARARs
Action/Media
Requirements
Prerequisite
Citation(s)
Classification of ground
water
Except for ground water in areas that have been
designated as Special Source Water, Site Specific
Impaired Ground Water, or meet the definition of
Unusable Ground Water, all Tennessee ground water is
designated General Use (GU) Ground Water.
Ground water classification in the State
of Tennessee - applicable
TDEC 0400-40-03-
,07(4Xb)
Restoration of contaminated
ground water
Except for naturally occurring levels, General Use
(GU) Ground Water:
(a) shall not contain constituents that exceed those
levels specified in subparagraphs (1 Xj) and (k) of
TDEC 0400-40-03-.03, [for the site related
contaminants of concern]; and
(b) shall contain no other constituents at levels'and
conditions which pose an unreasonable risk to the
public health or the environment.
Class GU ground waters with
contaminants) exceeding standards
listed in TDEC 0400-40-03.03 - relevant
and appropriate
TDEC 0400-40-03-08(2)
The waters shall not contain toxic substances, whether
alone or in combination with other substances, which
will produce toxic conditions that materially affect the
health and safety of man or animals, or impair the
safety of conventionally treated water supplies.
Available references include, but are not limited to:
Quality Criteria for Water (Section 304(a) of Public
Law 92-500 as amended); Federal Regulations tinder
Section 307 of Public Law 92-500 as amended; and
Federal Regulations under Section 1412 of the Public
Health Service Act as amended by the Safe Drinking
Water Act. (Public Law 93-523).
TDEC 0400-40-03-
03(1 Xi)
The waters shall not contain other pollutants in
quantities that may be detrimental to public health or
impair the usefulness of the water as a source of
domestic water supplv.
TDEC 0400-40-03-
¦03(1 Xk)
Shall not exceed the Safe Drinking Water Act National
Primary Drinking Water Regulations maximum
contaminant levels (MCLs) for inorganic site related
contaminants of concern, specified in 40 CFR
141.62(b)
Class GU ground waters which are an
existing or potential drinking water
source - relevant and appropriate
TDEC 0400-45-01-
06(1 Xb)
40 CFR 141.62(b)
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Table 24. Potential Chemical-specific ARARs
Action/Media
Requirements
Prerequisite
Citation(s)
Shall not exceed the Safe Drinking Water Act National
Primary Drinking Water Regulations maximum
contaminant levels (MCLs) for organic and volatile
organic site related contaminants of concern, specified
in 40CFR 141.61
TDEC 0400-45-01-
¦06(2)(a)
TDEC 0400-45-01-.25(2)
40CFR 141.61
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Table 25: Potential Location-specific ARARs and TBC Guidance
Location
Requirement
Prerequisite
Citation
Floodplains
Presence of
Floodplains
designated as such
on a map1
Shall take action to reduce the risk of flood loss, to minimize
the impact of floods on human safety, health and welfare,
and to restore and preserve the natural and beneficial values
served by floodplains.
Federal actions that involve potential
impacts to, or take place within,
floodplains - TBC
Executive Order 11988
Section 1. Floodplain
Management -
Shall consider alternatives to avoid, to the extent possible,
adverse effects and incompatible development in the
floodplain. Design or modify its action in order to minimize
potential harm to or within the floodplain
Executive Order 11988
Section 2(aX2) Floodplain
Management
Where possible, an agency shall use natural systems,
ecosystem processes, and nature-based approaches when
developing alternatives for consideration.
Executive Order 13690
Section 2(c)
Presence of .
floodplain
designated as such
on a map
The Agency shall design or modify its actions so as to
minimize2 harm to or within the floodplain.
Federal actions affecting or affected by
Floodplain as defined in 44 C.F.R. § 9.4
- relevant and appropriate
44C.F.R. §9.1 l(bXl)
Mitigation
The Agency shall restore and preserve natural and beneficial
floodplain values.
44 C.F.R. §9.11(b)(3)
Mitigation
The Agency shall minimize:
Potential harm to lives and the investment at risk from base
flood, or in the case of critical actions3 ftom the 500-year
flood;
Potential adverse impacts that action may have on floodplain
values.
44C.F.R. §9.1 l(cXl)and(3)
Minimization provisions
1 Under 44 C.F.R. § 9.7 Determination of proposed action's location, Paragraph (c) Floodplain determination. One should consult the FEMA Flood Insurance Rate Map (FIRM),
the Flood Boundary Floodway Map (FBFM) and the Flood Insurance Study (FIS) to determine if the Agency proposed action is within the base floodplain.
2 Minimize means to reduce to smallest amount or degree possible. See 44 C.F.R § 9.4 Definitions.
3 See 44 C.F.R § 9.4 Definitions, Critical action. Critical actions include, but are not limited to, those which create or extend the useful life of structures or facilities such as those
that produce, use or store highly volatile, flammable, explosive, toxic or water-reactive materials.
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Table 25: Potential Location-specific ARARs and TBC Guidance
Surface Waterbodies
Location
encompassing
aquatic ecosystem as
defined in 40 CFR
230.3(c)
No discharge of dredged or fill material into an aquatic
ecosystem is permitted if there is a practicable alternative
that would have less adverse impact.
No discharge of dredged or fill material shall be permitted
unless appropriate and practicable steps in accordance with
40 CFR 230.70 et seq. have been taken that will minimize
potential adverse impacts of the discharge on the aquatic
ecosystem.
Action that involves the discharge of
dredged or fill material into waters of
the United States, including
jurisdictional wetlands - applicable
40 CFR 230.10(a)
40 CFR 230.10(d)
Notes:
ARAR = Applicable or relevant and appropriate requirement
C.F.R. = Code of Federal Regulations
E.O. = Executive Order.
NWP = Nationwide Permit
TBC = To Be Considered [guidance]
U.S.C. = United States Code
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Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
Prerequisite
Citation(s)
General Construction Standards - AU Land-disturblne Activities (i.e., excavation, erading, etc.)
Activities causing
fugitive dust
emissions
Shall take reasonable precautions to prevent particulate matter from
becoming airborne; reasonable precautions shall include, but are not limited
to, the following:
• use, where possible, of water or chemicals for control of dust, and
• application of asphalt, oil, water, or suitable chemicals on dirt roads,
materials stock piles, and other surfaces which can create airborne
dusts;
Fugitive emissions from
demolition, construction
operations, grading, or the
clearing of land —applicable
TDEC 1200-3-8-.01(lXa)-
(b)
Shall not cause or allow fugitive dust .to be emitted in such a manner as to
exceed S minutes per hour or 20 minutes per day beyond property boundary
lines on which emission originates.
TDEC 1200-3-8-01(2)
Activities causing
storm water runoff
(e.g.. clearing,
grading, excavation)
Implement good construction management techniques (including sediment
and erosion controls, vegetative controls, and structural controls) in
accordance with the substantive requirements of General Permit No.
TNRI00000 to ensure that storm water discharge:
Dewatering or storm water runoff
discharges from land disturbed by
construction activity—
disturbance of 21 acre of total
land —applicable
TCA 69-3-1080)
TDEC 0400-40-10-03(2)
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Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
~~ Prerequisite
Citation(s)
Design, install and maintain effective erosion prevention and sediment
controls to minimize the discharge of pollutants. At a minimum, such
controls must be designed, installed and maintained to:
(1) Control stormwater volume and velocity to minimize soil erosion in
order to minimize pollutant discharges;
(2) Control stormwater discharges, including both peak flowrates and total
stormwater volume, to minimize channel and stream bank erosion and
scour in the immediate vicinity of discharge points;
(3) Minimize the amount of soil exposed during construction activity;
(4) Minimize the disturbance of steep slopes;
(5) Minimize sediment discharges from the site. The design, installation
and maintenance of erosion and sediment controls must address factors
such as the amount, frequency, intensity and duration of precipitation,
the nature of resulting stormwater runoff, and soil characteristics,
including the range of soil particle sizes expected to be present on the -
site;
(6) Provide and maintain natural buffers as described in Section 4.1.2,
. direct stormwater to vegetated areas and maximize stormwater
infiltration to reduce pollutant discharges, unless infeasible;
(7) Minimize soil compaction. Minimizing soil compaction is not required
where the intended function of a specific area of the site dictates that it
be compacted; and
(8) Unless infeasible, preserve topsoil. Preserving topsoil is not required
where the intended function of a specific area of the site dictates that
the topsoil be disturbed or removed.
Storm water discharges from
construction activities -TBC
General Permit No.
TNR100000
Section 4.1.1(1H8)
Activities causing
storm water runoff
(e.g., clearing,
grading, excavation)
Discharge.quality:
(a) The construction activity shall be carried out in such a manner that
will prevent violations of water quality criteria as stated in the
Tennessee Rules, Chapter 0400-40-03-.03. This includes, but is not
limited to, the prevention of any discharge that causes a condition in
which visible solids, bottom deposits or turbidity impair the
usefulness of waters of the state for any of the uses designated for
Storm water discharges from
construction activities -TBC
General Permit No.
TNR100000
Section 5.3.2(a)-(d)
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Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
Prerequisite
Citation(s)
that water body by Tennessee Rules, Chapter 0400-40-04.
Construction activity carried out in the manner required by this
permit shall be considered in compliance with the Tennessee Rules,
Chapter 0400-40-03-03.
(b) There shall be no distinctly visible floating scum, oil or other matter
contained in the stormwater discharge.
(c) The stormwater discharge must not cause an objectionable color
contrast in the receiving stream.
(d) The stormwater discharge must result in no materials in
concentrations sufficient to be hazardous or otherwise detrimental to
humans, livestock, wildlife, plant life or fish and aquatic life in the
receiving stream. This provision includes species covered under
Subpart 1.3.
Underground Injection Wells, Infiltration Galleries, and Groundwater Monitoring Wells - Installation, Operation, and Abandonment
Construction of
groundwater
monitoring well
All monitoring wells must be cased in a manner that maintains the integrity
of the monitoring well bore hole; this casing must be screened or perforated
and packed with gravel or sand, where necessary, to enable collection of
groundwater samples; the annular space above the sampling depth must be
sealed to prevent contamination of samples and the groundwater. ¦
Construction of RCRA
groundwater monitoring well—
relevant and appropriate
40 CFR 264.97(c)
TDEC 0400-12-01-
,06(6Kh)3
Abandonment of
groundwater
monitoring well
Cased wells shall be plugged and sealed with cement grout or bentonite (as
defined in subparagraph (c) of this paragraph) in accordance with the
requirements in subparagraphs 2(b) and 2(c) of this paragraph.
Permanent plugging and
abandonment of a well—relevant
and appropriate
TDEC 0400-45-09-. 16(2)
Wells extending into more than one aquifer shall be filled and sealed in such
a way that exchange of water from one aquifer to another is prevented.
TDEC 0400-45-09-. 16(3)
Injection of nutrients
(or other treatments)
into groundwater
The use of any Class V injection well in such a manner as to cause any
underground source of drinking water (USDW) to contain any substances that
are toxic, carcinogenic, mutagenic, or teratogenic, other than those of natural
origin, at levels and conditions which violate primary drinking water
standards as given in Chapter 0400-45-01 or adversely affect the health of
persons is prohibited.
Per 0400-45-06-.02 (3): "Injection well" means structure or device which is
used for the emplacement of fluids into a subsurface stratum including, but
Class V "injection well"
associated with remedial activity
and/or innovative or experimental
technologies as defined in TDEC
0400-45-06-.06(5)—applicable
TDEC 0400-45-06-
¦ 14(1 Xb)
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Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
Prerequisite
Citation(s)
not limited to: (a) a well used for the emplacement of fluids; (b) a subsurface
fluid distribution system; (c) an improved sinkhole; or (d) infiltration cell and
any other structures or devices designed, constructed or used to emplace
fluids into the subsurface, except as provided in paragraph (3) of Rule 0400-
45-06-.03; or (e) modified recharge point.
No injection activity can allow the movement of fluid containing any
contaminant into USDWs, if the presence of that contaminant may cause a
violation of any primary drinking water standard, or other health based
standards, or may otherwise adversely affect the health of persons. This
prohibition applies to well construction, operation, maintenance, conversion,
plugging, closure or any other injection activity.
TDEC 0400-45-06-
14(12Xa)l
Construction
Standards for Class
V injection wells
The variety of Class V well and their uses dictate a variety of construction
designs consistent with those uses, and precludes specific construction
standards. However, a well must be designed and constructed for its intended
use, in accordance with good engineering practices, and the design and
construction must be approved by the Commissioner.
Class V wells shall be constructed so that their intended use does not violate
the water quality standards.
Construction of Class V injection
wells - applicable
TDEC 0400-45-06-
l4(7Xa) and (b)
Operating
Requirements . for
Class V injection
wells
All Class V injection wells shall be operated in such a manner that they do
not violate the provisions of TDEC 0400-45-06-. 14(1) [i.e., prohibition
against using UIC well in such a manner as to cause USDW to contain
substances that are toxic, carcinogenic, mutagenic, or teratogenic at levels
and conditions which violate primary drinking water standards].
Operation of Class V injection
wells - applicable
TDEC 0400-45-06-
14(8Xa)
Monitoring
Requirements for
Class V Injection
Systems
The Commissioner may require monitoring of Class V injection wells; the
nature of which will be determined by the type of well, nature of the injected
fluid, and water quality of the receiving aquifer. The Commissioner shall
determine the extent and frequency of monitoring based on the type of
injection well and the nature of the injected fluid.
Note: Monitoring of any injection wells will be conducted pursuant to a
CERCLA Remedial Design or Remedial Action Work Plan after review by
TDEC and approval by the EPA.
Monitoring of Class V injection
wells - applicable
TDEC 0400-45-06-
,l4(9Xa) and (b)
Plugging and
The owner/operator must close the well in a manner that complies with the
Closure of a Class V injection
TDEC 0400-45-06-
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Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
Prerequisite
Citation(s)
abandonment of
Class V injection
wells
prohibition of fluid movement in subparagraph (a) of this paragraph. Also,
the owner/operator must dispose or otherwise manage any soil, gravel,
sludge, liquids, or other materials removed from or adjacent to the well in
accordance with all applicable Federal, State and local regulations and
requirements.
well—applicable
14(12Xb)
A Class V injection well shall be plugged with cement in a manner which
will not allow movement of fluids between underground sources of drinking
water.
TDEC 0400-45-06-
• 14(11Kb)
Any well that is to be permanently plugged and abandoned shall be
completely filled and sealed in such a manner that vertical movement of fluid
either into or between formation(s) containing USDWs through the bore hole
is not allowed.
TDEC 0400-45-06- .
,09(6Kd)
As a minimum, permanent seals must be placed in the bore hole opposite (1).
the lowermost confining bed, and (2) each intermediate confining bed
between successive formation(s) containing USDWs.
TDEC 0400-45-06-
09(6Xe)
Seals intended to prevent vertical movement of water in a well bore hole shall
be composed of cement, sand-and-cement, or concrete or other sealing
materials demonstrated to the satisfaction of the Commissioner to be
effective.
TDEC 0400-45-06-
.09(6X0
The minimum length of a seal required in subparagraph (0, of this paragraph,
shall be 20 feet.
TDEC 0400-45-06-
•09(6Xg)
The bore hole above the uppermost formation(s) containing a USDW shall be
filled with materials less permeable than the surrounding undisturbed
formations, the uppermost five (S) feet of the bore hole (at land surface) shall
be filled with a material appropriate to the intended use of the land.
TDEC 0400-45-06-
09(6Xh)
The materials used to fill spaces between well seals shall be filled with
disinfected dimensionally stable materials, compacted mechanically if
necessary to avoid later settlement except that cement, cement and sand, and
concrete do not require disinfection: Disinfection of well filling materials
shall be accomplished by using chlorine compounds such as sodium
hypochlorite or calcium hypochlorite.
TDEC 0400-45-06-
09(6X0
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Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
Prerequisite
Citation(s)
Placement of sealing
materials
Approved sealing materials used in abandonment operations shall be
introduced at the bottom of the well or interval to be sealed and placed
progressively upward to the top of the well. All such sealing materials shall
be placed in such a way as to avoid segregation or dilution of the sealing
materials.
TDEC 0400-45-06-
09(7Xa)
Permanent seals shall be placed in wells or bore holes opposite confining
beds between aquifers which are identifiable as, or are suspected of being,
hydraulically separated under natural, undisturbed conditions. After the
required seal has been installed, the remainder of the confining zone between
formations containing USDWs may be filled with sand, sand and gravel, or
other rock material acceptable to the Commissioner.
TDEC 0400-45-06-
¦09(7Xb)
Waste Characterization - Primary Wastes (e.g., contaminated media and debris) and Secondary Wastes (e.g., wastewaters, spent treatment media, etc.)
Characterization of
solid waste
Must determine if solid waste is excluded from regulation under 40 CFR
261.4(b); and
Generation of solid waste as
defined in 40 CFR 261.2 and
which is not excluded under 40
CFR 261 4(a) —applicable
40 CFR 262.11(a)
TDEC 0400-12-01-
¦03( I XbX 1)
Must determine if waste is listed as hazardous waste under 40 CFR Part 261;
or
Generation of solid waste which
is not excluded under 40 CFR
261.4(a)—applicable
40 CFR 262.11(b)
TDEC 0400-12-01-
03(1 XbX2)
Must determine whether the waste is (characteristic waste) identified in
subpart C of 40 CFR part 261 by either:
(1) Testing the waste according to the methods set forth in subpart C of 40
CFR part 261, or according to an equivalent method approved by the
Administrator under 40 CFR 260.21; or
(2) Applying knowledge of the hazard characteristic of the waste in light of
the materials or the processes used.
40 CFR 262.11(c)
TDEC 0400-12-01-
.03(1 XbX3)
Must refer to Parts 261,262,264,265,266,268, and 273 of Chapter 40 for
possible exclusions or restrictions pertaining to management of the specific
waste
Generation of solid waste which
is determined to be hazardous -
applicable
40 CFR 262.11(d);
TDEC 0400-12-01-
.03(1 XbX4)
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Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
Prerequisite
Citation(s)
Characterization of
hazardous waste (all
primary and
secondary wastes)
Must obtain a detailed chemical and physical analysis on a representative
sample of the waste(s), which at a minimum contains all the information that
must be known to treat, store, or dispose of the waste in accordance with
pertinent sections of 40 CFR 264 and 268.
Generation of RCRA-hazardous
waste for storage, treatment or
disposal - applicable
40. CFR 264.13(aXl)
Determinations for
management of
hazardous waste
Must determine if the hazardous waste has to be treated before land disposed.
This is done by determining if the waste meets the treatment standards in 40
C.F.R.268.40, 268.45, or 268.49 by testing in accordance with prescribed
methods or use of generator knowledge of waste.
This determination can be made concurrently with the hazardous waste
determination required in 40 C.F.R.§ 262.11.
Generation of RCRA hazardous
waste -applicable
40 C.F.R.§ 268.7(a)
TDEC 0400-12-01-
• lOdXgXlXO
-
Must comply with the special requirements of 40 C.F.R§ 268.9 in addition to
any applicable requirements in 40 C.F.R.§ 268.7.
Generation of waste or soil that
displays a hazardous
characteristic of ignitability,
corrosivity, reactivity, or toxicity
for storage, treatment or disposal
- applicable
40C.F.R.§268.7(aXl)
TDEC 0400-12-01-
¦ 10(1X8X1X0
Must determine each EPA Hazardous Waste Number (waste code) applicable
to the waste in order to determine the applicable treatment standards under 40
CFR 268 et seq..
Note: This determination may be made concurrently with the hazardous
waste determination required in Sec. 262.11 of this chapter.
Generation of RCRA hazardous
waste - applicable
40 CFR 268.9(a)
TDEC 0400-12-01-
lO(lXiXl)
Must determine the underlying hazardous constituents [as defined in 40 CFR
268.2(i)] in the characteristic waste.
Generation of RCRA
characteristic hazardous waste
(and is not D001 non-wastewaters
treated by CMBST, RORGS, or
POLYM of Section 268.42 Table
1) for storage, treatment or
disposal - applicable
40 CFR 268.9(a)
TDEC 0400-12-01-
-10(1X0(1)
Waste Staging and Storage - Primary Wastes (contaminated media and debris) and Secondary Wastes (wastewaters, spent treatment media, etc.)
Temporary storage of
hazardous waste in
containers
A generator may accumulate hazardous waste at the facility provided that:
• waste is placed in containers that comply with 40 CFR 265.171-173; and
Accumulation of RCRA
hazardous waste on site as
defined in 40 CFR 260.10—
40 CFR 262.34(a);
TDEC 0400-12-01-
03(4Xe)
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Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
Prerequisite
Citation(s)
applicable
40 CFR 262.34(aX 1 )(i);
TDEC 0400-12-01-
,03(4XeX2XiXI)
• the date upon which accumulation begins is clearly marked and visible
for inspection on each container
40 CFR 262.34(aX2);
TDEC 0400-12-01-
03(4XeX2Xii)
• container is marked with the words "hazardous waste" or
40 CFR 264.34(aX3)
TDEC 0400-12-01-
,03(4XeX2Xiii)
• container may be marked with other words that identify the contents
Accumulation of SS gal. or less of
RCRA hazardous waste at or near
any point of generation—
applicable
40 CFR 262.34(cXl)
TDEC 0400-12-01-
03(4XeX5XiX")
Use and management
of hazardous waste
in containers
If container is not in good condition (e.g. severe rusting, structural defects) or
if it begins to leak, must transfer waste into container in good condition.
Storage of RCRA hazardous
waste in containers—applicable
40 CFR 265.171
TDEC 0400-12-01-
05(9Xb)
Use container made or lined with materials compatible with waste to be
stored so that the ability of the container is not impaired.
40 CFR 265.172
TDEC 0400-12-01-
•05(9Xc)
Keep containers closed during storage, except to add/remove waste.
40 CFR 265.173(a)
TDEC 0400-12-01-
•05(9XdXl)
Open, handle and store containers in a manner that will not cause containers
to rupture or leak.
40 CFR 265.173(b)
TDEC 0400-12-01-
•05(9XdX2)
Storage of hazardous
waste in container
area
Area must have a containment system designed and operated in accordance
with 40 CFR 264.175(b).
Storage of RCRA-hazardous
waste in containers with free
liquids—applicable
40 CFR 264.175(a)
TDEC 0400-12-01-
¦06(9XfXl)
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Table 26. Potential Action-specific ARARs and TBC Guidance
. Action
Requirements
Prerequisite
Citation(s)
Area must be sloped or otherwise designed and operated to drain liquid from
precipitation, or Containers must be elevated or otherwise protected from
contact with accumulated liquid.
Storage of RCRA-hazardous
waste in containers that do not
contain free liquids —applicable
40 CFR 264.175(c)
TDEC 0400-12-01-
¦06(9X0(3)
Closure of RCRA
container storage unit
At closure, all hazardous waste and hazardous waste residues must be
removed from the containment system. Remaining containers, liners, bases,
and soils containing or contaminated with hazardous waste and hazardous
waste residues must be decontaminated or removed.
[NOTE: At closure, as throughout the operating period, unless the owner or
operator can demonstrate in accordance with 40 CFR 261 3(d) of this chapter
that the solid waste removed from the containment system is not a hazardous
waste, the owner or operator becomes a generator of hazardous waste and
must manage it in accordance with all applicable requirements of parts 262
through 266 of this chapter].
Storage of RCRA hazardous
waste in containers in a unit with
a containment system -
applicable
40 CFR 264.178
Temporary on-site
storage of
remediation waste in
staging pile (e.g.,
excavated soils)
Must be located within the contiguous property under the control of the
owner/operator where the wastes are to be managed in the staging pile
originated.
For purposes of this section, storage includes mixing, sizing, blending or
other similar physical operations so long as intended to prepare the wastes for
subsequent management or treatment.
Accumulation of solid non-
flowing hazardous remediation
waste (or remediation waste
otherwise subject to land disposal
restrictions) as defined in 40
C.F.R. 260.10-applicable
40 C.F.R. 264.554(aXl)
TDEC 0400-12-01-
,06(22Xe)l
Staging piles may be used to store hazardous remediation waste (or
remediation waste otherwise subject to land disposal restrictions) based on
approved standards and design criteria designated for that staging pile.
NOTE\ Design and standards of the staging pile should be included in
CERCLA Remedial Design document approved or issued by EPA.
40 C.F.R.§ 264.554(b)
Performance criteria
for staging pile
Staging pile must be designed to:
• facilitate a reliable, effective and protective remedy;
• must be designed to prevent or minimize releases of hazardous wastes
and constituents into the environment, and minimize or adequately
control cross-media transfer as necessary to protect human health and
the environment (for example through use of liners, covers, run-off/run-
on controls, as appropriate).
Storage of remediation waste in a
staging pile - applicable
40 C.F.R. 264.554(dXI)(i)
and (ii)
TDEC 0400-12-01-.06
(22Xe)4(i)
Page 37 of 49
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Walker Machine Products
Record of Decision
Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
Prerequisite
Citation(s)
Design criteria for
staging pile
In setting standards and design criteria must consider the following factors:
• Length of time pile will be in operation;
• Volumes of waste you intend to store in the pile;
• Physical and chemical characteristics of the wastes to be stored in the
unit;
• Potential for releases from the unit;
• Hydrogeological and other relevant environmental conditions at the
facility that may influence the migration of any potential releases; and
• Potential for human and environmental exposure to potential releases
from the unit.
Storage of remediation waste in a
staging pile - applicable
40 C.F.R. 264.554(dX2X0
-(vi)
TDEC 0400-12-01-.06
(22Xe)4
-------
Walker Machine Products
Record of Decision
Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
Prerequisite
Citation(s)
the base to comply with 40 C.F.R. 264.17(b).
(22Xe)6(iii)
Operational limits of
a staging pile
Must not operate for more than 2 years, except when an operating term
extension under 40 C.F.R. 264.554(i) is granted.
Note: Must measure the 2-year limit (or other operating term specified) from
first time remediation waste placed in staging pile
Storage of remediation waste in a
staging pile - applicable
40 C.F.R.
264.554(dXlX»i)
TDEC 0400-12-01-.06
(22Xe)4(iXIII)
Must not use staging pile longer than the length of time designated by EPA in
appropriate decision document.
40 C.F.R. 264.554(h)
Closure of staging
pile of remediation
waste
Must be closed within 180 days after the operating term by removing or
decontaminating all remediation waste, contaminated containment system
components, and structures and equipment contaminated with waste and
leachate.
Must decontaminate contaminated sub -soils in a manner that EPA
determines will protect human and the environment.
Storage of remediation waste in
staging pile in previously
contaminated area - applicable
40 C.F.R. 264.5540X1)
and (2)
TDEC 0400-12-01-.06
(22Xe)10
Must be closed within 180 days after the operating term according to 40
C.F.R. 264.258(a) and 264.111 or 265.258(a) and 265. 111.
Storage of remediation waste in
staging pile in. uncontaminated
area - applicable
40 C.F.R. 264.554(k)
TDEC 0400-12-01-.06
(22Xe)ll(i)
Treatment/Disposal of Wastes - Primary (e.g., contaminated media and debris) and Secondary Wastes (e.g., wastewaters, spent treatment media, etc.)
Disposal of RCRA-
hazardous waste in a
land-based unit
May be land disposed if it meets the requirements in the table "Treatment
Standards for Hazardous Waste" at 40 CFR 268.40 before land disposal.
Land disposal, as defined in 40
CFR 268.2, of restricted RCRA
waste—applicable
40 CFR 268.40(a)
TDEC 0400-12-01-
IO(3Xa)
All underlying hazardous constituents [as defined in 40C.F.R.§ 268.2(i)]
must meet the Universal Treatment Standards, found in 40 C.F.R.§ 268.48
Table UTS prior to land disposal.
Land disposal of restricted RCRA
characteristic wastes (D001-
D043) that are not managed in a
wastewater treatment system that
is regulated under the CWA, that
is CWA equivalent, or that is
injected into a Class 1
nonhazardous injection well -
applicable
40 CFR. § 268.40(e)
TDEC 0400-12-01-
IO(3XaX5)
Page 39 of 49
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Walker Machine Products
Record of Decision
Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
Prerequisite
Citation(s)
Disposal of RCRA
hazardous waste soil
in a land-based unit
Alternative land disposal restrictions (LDR) treatment standards for
contaminated soils - Must be treated according to the alternative treatment
standards of 40 C.F.R.§ 268.49(c) or according to the UTSs specified in 40
C.F.R.§ 268.48 applicable to the listed and/or characteristic waste
contaminating the soil prior to land disposal.
Land disposal, as defined in 40
C.F.R.§ 268.2, of restricted
hazardous soils -applicable
40 CFR.§ 268.49(b)
TDEC 0400-12-01-
¦10(3)0X2)
Treatment of RCRA
hazardous waste soil
Prior to land disposal, all "constituents subject to treatment" as defined in 40
C.F.R.§ 268.49(d) must be treated as follows.
Treatment of restricted hazardous
waste soils - applicable
40 CFR.§268.49(cXl)
TDEC 0400-12-01-
10(3X1X3X0
For non-metals (except carbon disulfide, cyclohexanone, and methanol),
treatment must achieve a 90 percent reduction in total constituent
concentrations, except as provided in 40 C.F.R.§ 268.49(cXl XQ.
40CFR.§268.49(cXlXA)
TDEC 0400-12-01-
.10(3XiX3X>XI)
Treatment of RCRA
hazardous waste soil
(com'd)
For metals and carbon disulfide, cyclohexanone, and methanol), treatment
must achieve a 90 percent reduction in total constituent concentrations as
measured in leachate from the treated media (tested according to TCLP) or 90
percent reduction in total constituent concentrations (when a metal removal
technology is used), except as provided in 40 C.F.R.§ 26849(cX1XQ-
40CFR.§268.49(cX1XB)
TDEC 0400-12-01-
10(3XiX3X'XII)
When treatment of any constituent subject to treatment to a 90 percent
reduction standard would result in a concentration less than 10 times the
Universal Treatment Standard for that constituent, treatment to achieve
constituent concentrations less than 10 times the universal treatment standard
is not required. [Universal Treatment Standards (UTS) are identified in 40
C.F.R.§ 268.48 Table UTS],
40 CFR.§268.49(cXlXC)
TDEC 0400-12-01-
.IO(3XjX3X'X"I)
In addition to the treatment requirement required by paragraph (cX 1) of 40
C.F.R.§ 268.49, soils must be treated to eliminate these characteristics.
Treatment of soils that exhibit the
hazardous characteristic of
ignitability, corrosivity, or
reactivity - applicable
40CFR.§268.49(cX2)
TDEC 0400-12-01-
10(3XjX3XiO
Disposal of RCRA
hazardous debris in a
land-based unit
Must be treated prior to land disposal as provided in 40 C.F.R.§ 268.45(aXI)-
(S) unless EPA determines under 40 C.F.R.§ 26l.3(fX2) that the debris no
longer contaminated with hazardous waste or the debris is treated to the
waste-specific treatment standard provided in 40 C.F.R.§ 268.40 for the
waste contaminating the debris.
Land disposal, as defined in 40
C.F.R.§ 268.2, of RCRA-
hazardous debris -applicable
40 CFR.§ 268.45(a)
TDEC 0400-12-01-
¦10(3X0
Page 40 of 49
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Walker Machine Products
Record of Decision
Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
Prerequisite
Citation(s)
Debris treated by one of the specified extraction or destruction technologies
on Table 1 of 40 C.F.ft§ 268.45 and which no longer exhibits a characteristic
is not a hazardous waste and need not be managed in RCRA Subtitle C
facility.
Hazardous debris contaminated with listed waste that is treated by
immobilization technology must be managed in a RCRA Subtitle C facility.
Treated debris contaminated with
RCRA-listed or characteristic
waste - applicable
40 CFR. § 268.45(c)
TDEC 0400-12-01-
.10(3X0
Disposal of
hazardous debris
treatment residues
Except as provided in 268.45(dX2) and (dX4), must be separated from debris
by simple physical or mechanical means, and such residues are subject to the
waste-specific treatment standards for the waste contaminating the debris.
Residue from treatment of
hazardous debris - applicable
40 CFR.§ 268.45(d)(1)
TDEC 0400-12-01-
10(3X0(4)
Disposal of RCRA
hazardous
wastewaters into
CWA wastewater
treatment unit
Waste otherwise restricted under TDEC 0400-12-01-. 10 are not prohibited
from land disposal if the waste meet any of the following criteria, unless the
wastes are subject to a specified method of treatment other than DEACT in
40 CFR 268.40, or are D003 reactive cyanide:
(I) The wastes are managed in a treatment system which subsequently
discharges to waters of the U.S. pursuant to a permit issued under section 402
of the Clean Water Act; or
(II) The wastes are treated for purposes of the pretreatment requirements of
section 307 of the Clean Water Act; or
(III) The wastes are managed in a zero discharge system engaged in Clean
Water Act-equivalent treatment as defined in part (2Xh)l of this rule; or
(IV) The wastes no longer exhibit a prohibited characteristic at the point of
land disposal.
NOTE: For purposes of this exclusion, a CERCLA on-site wastewater
treatment unit that meets all of the identified CWA ARARs for point source
discharges from such a system, is considered a wastewater treatment system
that is NPDES permitted.
Restricted RCRA characteristic
hazardous wastewaters managed
in a wastewater treatment system
—applicable
40 CFR 268.1(cX4)
TDEC 0400-12-01-.10(1)
(aX3Xiv)
Ex Situ Air Phase Treatment Systems (e.g., SVE or Air Stripper Systems-Emissions and Process Vents)
Emissions from Ex
No discharge of visible emission from any air contaminant source with an
Visible emissions of air pollutants
TDEC 1200-03-05.01(1)
Page 41 of 49
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Walker Machine Products
Record of Decision
Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
Prerequisite
Citation(s)
Situ Air Phase
treatment systems
(e.g. SVE, air
strippers)
opacity in excess of 20% for an aggregate of more than 5 minutes in any one
hour or more than 20 minutes in any 24-hour period.
from any air contaminant source
as defined in TDEC 1200-3-
2.01(1 Kb) - applicable.
Construction of a new air contaminant source or the modification of an air
contaminant source which may result in the discharge of air. contaminants
must be in accordance with this Division 1200-03; Division 0400-30; any
applicable measures of the control strategy; and the Tennessee Air Quality
Act.
Emissions of air pollutants from
new air contaminant sources as
defined in TDEC 1200-3-
2.01 (1 Kb) - applicable.
TDEC 1200-03-09-
-01(1 Xd)
Air contaminant sources must take all reasonable measures to keep emissions
to minimum during startups, shutdowns, and malfunctions. Measures may
include installation and use of alternate controls systems, changes in
operating methods/procedures, cessation of operation during repairs,
maintaining sufficient spare parts, etc.
Emissions from air contaminant
source due to malfunction, or
during startup or shutdown -
applicable.
TDEC 1200-03-20.02(1)
TDEC Technical Secretary shall be notified within 24 hours of the
occurrence of a malfunction which causes emission of air contaminants in
excess of applicable emissions standards in TDEC 1200-3, or of sufficient
duration to cause damage to property or public health.
TDEC 1200-03-20.03(1)
Treatment of
hazardous waste in
miscellaneous
Treatment Unit with
air emissions (e.g.
SVE, air strippers)
Unit must be located, designed, constructed, operated and maintained, and
closed in a manner that will ensure protection of human health and the
environment.
Treatment of RCRA hazardous
waste in miscellaneous units,
except as provided in 40 CFR
264.1 - relevant and
appropriate
40 CFR 264.601
Protection of human health and the environment includes^ but is not limited
to: prevention of any release that may have adverse effects on human health
or the environment due to migration of waste constituents in the air,
considering the factors listed in 40 CFR 264.60l(cXl) thru (7).
40 CFR 264.601(c)
The requirements of RCRA Subpart AA-Air Emission Standards for Process
Vents do not apply to process vents that would otherwise be subject to this
subpart when equipped with emission controls and operated in accordance
Process vents associated with air
or steam stripping operations that
manage hazardous wastes with
40 CFR 264.1030(e) .
Page 42 of 49
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Walker Machine Products
Record of [Decision
Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
Prerequisite
Citation(s)
with an applicable Clean Air Act regulation codified under 40 CFR part 60,
part 61 or part 63.
organic concentrations of at least
10 ppmw - relevant and
appropriate
The requirements of RCRA Subpart CC - Air Emission Standards for Tanks,
Surface Impoundments, and Containers do not apply to a waste management
unit that is solely used for on-site treatment or storage of hazardous waste
that is placed in the unit as result of implementing remedial activities required
under RCRA 3004(u) and (v), or 3008(h), or CERCLA authorities.
Air pollutant .emissions with
volatile organics from a
hazardous waste tank, surface
impoundment, or container -
relevant and appropriate
40 CFR 264.1080(aX5)
General standards for
process vents used in
treatment of VOC
contaminated wastes
and groundwater
Select and meet the requirements under one of the options specified below:
• Control HAP emissions from the affected process vents according to the
applicable standards specified in §§ 63.7890 through 63.7893.
Process vents as defined in 40
CFR 63.7957 used in site
remediation of media (e.g.,
groundwater) that could emit
hazardous air pollutants (HAP)
listed in Table 1 of Subpart
GGGGG of Part 63 and vent
stream flow exceeds the rate in 40
CFR 63.7885(cXl) - relevant
and appropriate.
40 CFR 63.7885(b)
40 CFR 63.7885(bX 1)
• Determine for the remediation material treated or managed by the
process vented through the affected process vents that the average total
volatile organic hazardous air pollutant (VOHAP) concentration, as
defined in § 63.7957, of this material is less than 10 parts per million by
weight (ppmw). Determination of VOHAP concentration will be made
using procedures specified in § 63.7943.
40 CFR 63.7885(bX2)
• Control HAP emissions from affected process vents subject to another
subpart under 40 CFR part 61 or 40 CFR part 63 in compliance with the
standards specified in the applicable subpart.
40 CFR 63.7885(bX3)
Emission limitations
for process vents
used in treatment of
VOC contaminated
wastes and
Meet the requirements under one of the options specified below:
• Reduce from all affected process vents the total emissions of the HAP to
a level less than 1.4 kilograms per hour (kg/hr) and 2.8 Mg/yr (3.0
pounds per hour (Ib/hr) and 3.1 tpy); or
Process vents as defined in 40
CFR 63.7957 used in site
remediation of media (e.g., soil
and groundwater) that could emit
hazardous air pollutants (HAP)
40 CFR 63.7890(b)
TDEC 1200-1-11-
05(27XcXl)
Page 43 of 49
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Walker Machine Products
Record of Decision
Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
Prerequisite
Citation(s)
groundwater
listed in Table 1 of Subpart
GGGGG of Part 63 and vent
stream flow exceeds the rate in 40
CFR 63.7885(cXl)-relevant and
appropriate.
40 CFR 63.7890(bXl)
TDEC 0400-12-01-
,O5(27XcXlX0
• Reduce from all affected process vents the emissions of total organic
compounds (TOC) (minus methane and ethane) to a level below 1.4
kg/hr and 2.8 Mg/yr (3.0 Ib/hr and 3:1 tpy); or
40 CFR 63.7890(bX2)
• Reduce from all affected process vents the total emissions of the HAP by
95 percent by weight or more; or
40 CFR 63.7890(bX3)
TDEC 0400-12-01-
,05(27XcXlXii)
• Reduce from all affected process vents the emissions of TOC (minus
methane and ethane) by 95 percent by weight or more.
40 CFR 63.7890(bX4)
• For each closed vent system and control device you use to comply with
paragraph (b) of this section, you must meet the operating limit
requirements and work practice standards in §63.7925(c) through (j) that
apply to your closed vent system and control device.
40 CFR 63.7890(c)
Transportation of Wastes - Primary and Secondary Wastes
Transportation of
hazardous materials
Shall be subject to and must comply with all applicable provisions of the
HMTA and HMR at 49 CFR 171 -180.
Any person who, under contract
with a department or agency of
the federal government,
transports "in commerce," or
causes to be transported or
shipped, a hazardous material
—applicable
49 CFR 171.1(c)
Transportation of
hazardous waste off-
site
Must comply with the generator requirements of 40 CFR 262.20-23 for
manifesting, Sect. 262.30 for packaging, Sect. 262.31 for labeling,
Sect. 262.32 for marking, Sect. 262.33 for placarding and Sect. 262.40,
262.41(a) for record keeping requirements and Sect. 262.12 to obtain EPA ID
number.
Preparation and initiation of
shipment of RCRA hazardous
waste off-site—applicable
40 CFR 262.10(h)
TDEC 0400-12-01-
.03(1 Xa)8
Transportation of .
The generator manifesting requirements of 40 CFR 262.20-262.32(b) do not
Transportation of hazardous
40 CFR 262.20(f)
Page 44 of 49
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Walker Machine Products
Record of Decision
Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
Prerequisite
Citation(s)
hazardous waste on-
site
apply. Generator or transporter must comply with the requirements set forth
in 40 CFR 263.30 and 263.31 in the event of a discharge of hazardous waste
on a private or public right-of-way.
wastes on a public or private
right-of-way within or along the
border of contiguous property
under the control of the same
person, even if such contiguous
property is divided by a public or
private right-of-way - applicable
Management of
samples (e.g.,
contaminated soils
and wastewaters)
Are not subject to any requirements of 40 CFR Parts 261 through 268 or 270
when:
Generation of samples of
hazardous waste for purpose of
conducting testing to determine
its characteristics or composition-
-applicable
40 CFR 261.4(dXl)
• The sample is being transported to a laboratory for the purpose of
testing;
40 CFR 261.4(d)(lX(i)
• The sample is being transported back to the sample collector after
testing; and
40 CFR 261.4(dX IX")
• The sample collector ships samples to a laboratory in compliance with
U.S. Department of Transportation, U.S. Postal Service, or any other
applicable shipping requirements, including packing the sample so that it
does not leak, spill or vaporize from its packaging.
40 CFR 261.4(dX2)
Waste left in place
Institutional controls are required and shall include, at a minimum, deed
restrictions for sale and use of property, and securing the area to prevent
human contact with hazardous substances which pose or may pose a threat to
human health or safety.
Hazardous substances left in
place that may pose an
unreasonable threat to public
health, safety, or the
environment—TBC
TDEC 0400-15-01-.08(10)
Notes:
ARAR = Applicable or relevant and appropriate requirement UIC = Underground Injection Control
CFR = Code of Federal Regulations UTS = Universal Treatment Standard
CWA = Clean Water Act of 1972 USDW = Underground Source of Drinking Water
DOT = U.S. Department of Transportation
EPA = U.S. Environmental Protection Agency
RCRA = Resource Conservation and Recovery Act of 1976
HMR = Hazardous Materials Regulations
Page 45 of 49
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Walker Machine Products
Record of Decision
Table 26. Potential Action-specific ARARs and TBC Guidance
Action
Requirements
¦ Prerequisite
Citation(s)
HMTA = Hazardous Materials Transportation Act
TBC = To be considered
TCA - Tennessee Code Annotated
TDEC = Rules of the Tennessee Department of Environment and Conservation, Chapter noted
IDW = Investigation Derived Waste
Page 46 of 49
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Walker Machine Products
Record of Decision
Table 27. Cost Comparison of UZ Remedial Alternatives
UZ#1
UZ#2a
UZ #2b*
UZ #3
UZ#4
UZ Remedial Alternative
No Action
SVE with Limited Air
Sparge
TE-SVE with
Limited Air Sparse
Limited Soil Excavation
with SVE
ISCO and SVE
Unit Rate (cost/per cubic yard)
.
$28
$60
$66EX/$26SVE
$61ISCO/$66SVE
Capital Cost
$0
$2,001,999
$5,285,201
$2,722,209
$2,627,391
NPW O&M Cost
$39,987
$976,135
$976,135
$738,963
$738,963
O&M Period (years)
30
5
5
5
5
Net Present Work Cost (@5%
discount cost)
$40,000
$2,978,100
$6,261,300
$3,461,200
$3,366,400
Notes:
NPW - Net Present Worth
O&M - Operation & Maintenance
SVE - Soil Vapor Extraction
TE-SVE - Thermal Enhanced Soil Vapor Extraction
EX - Excavation
ISCO - In Situ Chemical Oxidation
*UZ #2B is the EPA's preferred alternative for the UZ.
Page 47 of 49
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Walker Machine Products
Record of Decision
Table 28. Cost Comparison of SSZ Remedial Alternatives
SSZ #1
SSZ #2
SSZ #3
SSZ #4
SSZ #5*
SSZ Remedial Alternative
No Action
• GR&T/Hydraulic
Containment
ISCO
EISB with ISCR
BiRD
Unit Rate (cost/per cubic yard)
-
-
$283
$164
#132
Capital Cost
$0
$479,959
$4,446,211
$2,396,036
$1,605,753
NPW O&M Cost
$39,987
$1,132,680
$82,934
$82,766
$391,246
O&M Period (years)
30
20
5
5
3
Net Present Work Cost (@5%
discount cost)
$40,000
$1,612,600
. $4,529,100
$2,478,800
$1,997,000
Notes:
NPW - Net Present Worth
O&M - Operation & Maintenance
GR&T - Groundwater Recovery and Treatment
ISCO - In Situ Chemical Oxidation
EISB - Enhanced In Situ Bioremediation
ISCR - In Situ Chemical Reduction
BiRD - Biogeochemical Reductive Dehalogenation
*SSZ #5 is the EPA's preferred alternative for the SSZ.
Page 48 of 49
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Walker Machine Products
Record of Decision
Table 29. Cost Comparison of DP Remedial Alternatives
DP #1
DP #2
DP #3*
DP #4
DP Remedial Alternative
No Action
GR&T/Hydraulic Containment
EISB Passive Barriers with
Horizontal Well
MNA
Unit Rate (cost/per cubic vard)
.
-
-
.
Capital Cost
$0
$659,583
$1,448,081
$0
NPW O&M Cost
$39,987
$1,159,299
$1,001,623
$187,078
O&M Period (years)
30
20
20
30
Net Present Work Cost (@5%
discount cost)
$40,000
$1,818,900
$2,449,700
$187,100
Notes:
NPW - Net Present Worth
O&M - Operation & Maintenance
GR&T - Groundwater Recovery and Treatment
EISB - Enhanced In Situ Bioremediation
MNA - Monitored Natural Attenuation
*DP #3 is the EPA's preferred alternative for the DP.
Page 49 of 49
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Walker Machine Products
Record of Decision
August 2018
FIGURES
-------
walker Machine Products
Record of Decision
August 2018
soyia!
Approximate Site Boundary
1—~-5fcr
MAO S3 ffclW Pl«n* T«
Site Location Map
Walker Machine Site
Collierville, Shelby County, Tennessee
JWWSOI,
Cfly tlUMMt
Ntihv IN
Cordova
HmnwhH
llHlm Roc*
I Cdliervitle TN
1 inch =150 miles
1 inch = 5 miles
IwtriHt Ftll
G-»rnjr»tewn
Montgomery
Ohn IrncA
[walker Machine Stle |
PtftUMo*
Jtckton
-------
Walker Machine Products
Record of Decision
August 2013
anufac'unr.g Build
Witt
International, Inc
location ot Former AS!
\ r_
Oil/Wate
Overflow Pond
Approximate Location
of Intermittent Stream
Approximate Location
of Ditch
Site Features
lAfci^SASj
Site Boundary
F«t
WOO aw Plan* To
Site Layout Map
Walker Machine Site
Collierville, Shelby County, Tennessee
rrromwTrrr
-------
Walker Machine products
Record of Decision
August 2018
iUi
Aw
L*
*Mr> •»«>.* m
tC
|Uit«V
n
WMMr Uj nitH
St*
«
Wellfield Location
r~
Site Boundary
N
A
250 500
Fe«l
NAOfiJ Stan KlHlmMM FM
Collierville Wellfield 1 Location
Walker Machine Site
Collierville, Shelby County, Tennessee
Figure
3
-------
Walker Machine Products
Record of Decision
August 2018
Figure 4
Idealized Conceptual Site Model
Walker Machine Site, Collierville, Tennessee
City of Collierville
Wellfield ffl
Unnamed
intermittent
Stream
Former A5T and
Intermittent
Overflow Pond
Street
No Apparent Contamination Deeper than 100 ft t»is I observed dur
-------
Walker Machine Products
Record of Decision
August 2018
Figure 5 Human Health Risk Assessment Conceptual Site Model
Walker Machine Products Site
Collierville, Tennessee
Primary
Source
Spills, leaks
and waste
from
process
operations,
sewer
drains, and
Oil/Water
Separator
"gestion
Potential Human Receptors
Exposure
Route
two
Dermal Contact
Surface ^ Ingestion
Oermal Contact
ngestion
Dermal Contact
* Inhalation
ater "8""°"
Inhalation
Dermal Contact
Ingestion
»Inhalation
Dermal Contact
Current
Receptor*
a
ii
i!
"!
future Receptors
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Walker Machine Products
Record of Decision
August 2018
Figure 6
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Walker Machine Produce
Record of Decision
August 2018
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Walker Machine Site
Collierville, Shelby County. Tennessee
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Walker Machine Products
Record of Decision
August 2018
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Walker Machine Products
Record of Decision
August 2018
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Walker Machine Products
Record of Decision
August 2018
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Walker Machine Products
Record of Decision
August 2018
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Walker Machine Products
Record of Decision
August 2018
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Walker Machine Products
Record of Decision
August 2018
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Walker Machine Products
Record of Decision
August 2018
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14
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Walker Machine Products
Record of Decision
August 2018
Soil Gas Indoor and AmBtentAif Exceeaances olEPA RSLs br Residential Air (HQ»0 1)
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walker Machine products
Record of Decision
August 2018
Manufactu'r,
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L-Mbkyai
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Walker Machine Products
Record of Decision
August 2018
APPENDIX A
TRANSCRIPT OF JUNE 14, 2018 PUBLIC MEETING
-------
WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
Public Meeting on 06/14/2018
1
2
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 4 - SUPERFUND DIVISION
WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE
PROPOSED PLAN. PUBLIC MEETING
DATE:
TIME:
LOCATION:
APPEARANCES
June 14, 2018 (Thursday)
6:01p.m.
Lucius E. And Elise C. BUrch, Jr.
Library
501 Poplar View Parkway Collierville,
Tennessee 38017
RANDY BRYANT
EPA Remedial Project Manager
Superfund Division
KERISA COLEMAN
EPA Community Involvement Coordinator
Enforcement & Community Engagement
Branch
Superfund Division
JAMIE A. WOODS, P.G.
Environmental Specialist
State of Tennessee Department of
Environmental and Conservation
Division of Remediation
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WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
Public Meeting on 06/14/2018 Page 2
1 PROCEEDINGS
2 **********
3 MR. BRYANT: All right. Well, it looks
4 like we're going to have a very intimate and
5 casual group tonight, so I will try to keep
6 things moving along pretty quickly.
7 My name is Randy Bryant. I'm with the
8 US EPA, Environmental Protection Agency. We
9 have a regional office in Atlanta.
10 This is Kerisa Coleman. She's a
11 community involvement coordinator, so she works
12 on various sites. I'm the protect manager for
13 this site and several others, so I manage, you
14 know, all the activities that go on. And Kerisa
15 manages a set of activities at a bunch of sites.
16 So she stays busy traveling to various sites,
17 and I focus on particular sites.
18 Tonight1s meeting is about the Walker
19 Machine Product site in Collierville. It's over
20 there on Washington Street. And the purpose of
21 the meeting is to discuss the studies that we've
22 done, and the cleanup plans that we have come up
23 with, and our preferred one.
24 And it's important for us to do the
25 meeting and have a comment period because that
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WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
Public Meeting on 06/14/2018 Page 3
1 helps us get to the stage where we can make a
2 final decision and proceed on with design and
3 cleanup.
4 So, naturally, I've got a PowerPoint
5 presentation. I'll try to make it as painless
6 as possible. Certainly, if you think of
7 questions, feel free -- I mean, one of the
8 purposes of having this meeting is to answer
9 some of your questions.
10 And then if you think of questions
11 after you leave, you'll have our contact
12 information, either phone numbers or e-mails, so
13 you'll be able to get ahold of us. We have a
14 comment period that will run through July 7th.
15 You can submit comments either by regular mail,
16 e-mail. I mean, you can call, but the preferred
17 way is, if you want to make a particular
18 comment, is to submit it in writing.
19 Very briefly, the law that deals with
20 - this site and similar sites is called the
21 Superfund law or CERCLA is the acronym. It
22 dates back to 1980. It's a law that deals with
23 releases of contaminants from industrial
24 properties.
25 It provides authority for doing
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WALKER MACHINE PRODUCTS, INC- SUPERFUND SITE PROPOSED PLAN
Public Meeting on 06/14/2018 Page 4
1 short-term cleanups or long-term cleanups, and
2 what I work on are long-term cleanups. It also
3 provides a way to -- for government funding if
4 you don't have responsible parties. Most of the
5 time, I'd say probably 70 to 75 percent of our
6 sites, they're responsible parties who are
7 required to pay for the studies and the cleanup.
8 Here at Walker Machine Products, there
9 is no responsible party, so the government has
10 paid for the studies so far, and we're expecting
11 to pay for the cleanup going forward.
12 This just gives you an outline and kind
13 of the steps that I need to go through, you
14 know, to work through investigating a site and
15 doing cleanup. And that's -- if you
16 particularly want this little diagram, it's
17 available on the back table as well.
18 The site is on the NPL, the National
19 Priorities List. That means that it is
20 considered a high priority for doing a study.
21 It doesn't also -- it doesn't always translate
22 that it needs to have a significant cleanup, but
23 you need to have some studies done. But it is
24 on the NPL, and we've done -- we've gone through
25 a few steps.
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WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
Public Meeting on 06/14/2018 Page 5
1 We've done the remedial investigation,
2 which is just the sampling studies. We've gone
3 through the feasibility study where you're
4 looking at the different cleanup alternatives
5 that are possible. And we're at the stage now
6 where we've issued the proposed plan, which if
7 you were on the mailing list you got one. If
8 not, there is the fact sheet on the back table.
9 And, you know, it's also available to you on the
10 website just listed on the handout in the back.
11 But we're at the proposed-plan stage.
12 And we have this meeting, we do the comment
13 period, and then depending on the feedback that
14 we get, we could proceed with our preferred
15 alternative or we could end up making some
16 changes.
17 After we have the comment period and do
18 the responsiveness summary and close that out,
19 then we can get to actually issuing the record
20 decision, which is just the final decision for
21 the cleanup.
22 These are, kind of, the four questions
23 that you should feel like get answered tonight.
24 And if they don't, then you can always ask me
25 for more information. But the whole purpose of
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WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
Public Meeting os 06/14/2018 Page 6
1 doing site studies is to figure out, you know,
2 what it is* where it is, you know, why -do we
3 think it's a problem, and how are you going to
4 fix it,
5 . "And just some background on the site:
6 It's a five-acre property over there on
7 Washington. Street. The operations that
8 contributed to the contamination that we're
9 looking at really date back as far back as the
10 mid-•60s. That's when Walker Machine Products
11 - first opened for business at that location.
12 And they just used lathes to make small
13 metal parts. And they used common industrial
14 solvents, PCE and TCE, to clean the parts. And
15 ' the solvent, in some cases, apparently, was just
16 drained through the ground. Sometimes it went
17 to the oil/water separator or it went to a tank.
18 This map gives you at least some idea.
19 And how well -- are you getting much glare? , Can
20 you see that fairly well?
21 I 'm good. Uh-huh.
22 MR. BRYANT: Okay.
23 - The yellow outline shows you the
24 property boundary. The long, narrow building
25 that's oriented north-south or up and down in
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WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
Public Meeting on 06/14/2018 Page 7
1 this picture is the main production building.
2 The little building to the right is just a --
3 it1s a storage building. They're using it for a
4 countertop shop now.
5 Back here, this little purple dot,
6 that's where the oil/water separator is. This
7 little yellow dot, we found a few drums, back
8 there in the woods. I mean they're empty at
9 this point, but there are drum carcasses back
10 there. This little blue dashed line is a little
11 stream that's back there on the south side of
12 the property.
13 You've got industrial commercial
14 properties around there, but you've also got a
15 lot of residential development that's come in
16 roughly within, like, a half mile or so of the
17 site. It's been built up over the last, what --
18 right at three to five years?
19 MS. COLEMAN: I want to say.. Yeah.
2 0 MR. BRYANT: And groundwater in this
21 - area is about 60 feet down before you hit the
22 groundwater. When you get down to the aquifer,
23 you know -- this is the Memphis Sands Aquifer.
24 It's an important aquifer in this area. Shelby
25 County depends on the Memphis Sands Aquifer for
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WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
Public Meeting on 06/14/2018 Page 8
1 it's drinking water, so that's why it's
2 important to us.
3 Collierville operates several water
4 plants. Water plant number one is the closest
5 one to the site. It's about half a mile west --
6 northwest of the site. There's been PCE that
7 showed up in one of their supply wells. And
8 they have three supply wells at water plant
9 number one.
10 But in terms of finished water, you
11 know, what's going into the drinking water
12 system, that is still meeting drinking water
13 standards. And the last time they tested it, it
14 was actually non-detect in the finished water
15 from the plant. And they sample quarterly.
16 And there's good coordination that goes
17 on in between the town, TDEC, and EPA. And the
18 main point I want to make about what we see at
19 water plant number one is that, one, even though
20 it's PCE, it's not positive that it comes from
21 the site; two, it is being monitored; and,
22 three, the agencies are coordinating together,
23 and the situation is in hand.
24 If something changes, you know, we have
25 a good relationship, and we'll just work
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WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
Public Meeting on 06/14/2018 Page 9
1 together and we'll deal with it. But for now,
2 Collierville can handle what they see at water
3 plant number one. And the thing for us to do is
4 to deal with the source of contamination that we
5 know of at Walker Machine just to make sure that
6 in the future, you know, groundwater
7 contamination doesn't spread further.
8 And y'all probably know this, but this
9 just gives you a better idea of the relationship
10 between the site and wellfield number one. The
11 site's over here with the blue sign on the far
12 right, and then the wellfield number one is on
13 the far left. That's where the green water
14 tower is.
15 And I think I mentioned, you know, the
16 government has paid for the sampling study so
17 far. We call it a fund lead project when the
18 government is paying for it. We sampled soil
19 and groundwater sediment and also indoor air at
2 0 the main plant building.
21 And there have been other studies done
22 in the past that have also collected samples on
23 a smaller scale. They've done some groundwater
24 sampling. They've done soil-gas sampling. And
25 we used some of that data to help us guide where
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WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
Public Meeting on 06/14/2018 Page 10
1 we did our sampling.
2 And just a little graphic to kind of
3 try to summarize, you know, the site and how you
4 have release mechanisms, the depths of the
5 water, the direction of groundwater flow, we
6 just call this our conceptional site model.
7 It's contained within, you know, the RFFS
8 documents, but it's just, again, summarized
9 here.
10 You have -- I think I mentioned you
11 have the water table. It's fairly deep. You
12 don't hit a water table until probably 50 or 60
13 feet below grade. And you have a few places
14 where you have some fingers or lenses of clay or
15 some tight silts. It's not continuous across
16 the entire property, but you do have it in
17 places. And it does seem to be helping contain
18 the contamination that we see. Because in
19 groundwater, you really don't see contamination
20 deeper than, say, roughly 80 or 90 feet.
21 Again, coming back to those basic
22 questions, 'you know, water contaminants that
23 we're most concerned with, and they're PCE and
24 TCE and some related compounds. And when I say
25 "related compounds," I mean stuff that is either
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WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
Public Meeting on 06/14/2018 Page 11
1 a breakdown product -- because PCE and TCE will
2 break down slowly on their own in the
3 environment. So we 1 re seeing some of the
4 breakdown products, but not as much as we'd like
5 to see.
6 And where are they? Well, they're in
7 soil, you know, in parts of the site at depths
8 ranging anywhere from 1 to possibly 50 feet
9 deep. They're in groundwater under parts of the
10 site and adjacent property at depths of roughly
11 60 to 90 feet. And they were detected in indoor
12 air in the main building at the site.
13 This is a good graphic and can give you
14 some idea of where the groundwater contamination
15 is. If you would notice here in the very center
16 of the picture, you see a very small red dot.
17 That's where the concentrations are highest in
18 the monitoring wells.
19 And as you step away in the varying
2 0 shades of purple, the concentrations decrease.
21 And once you're at the very extreme edge, you're
22 talking, you know, barely detectable levels, at
23 least in these monitoring wells. But that gives
24 you an idea of where the groundwater
25 contamination is.
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-------
WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
Public Meeting on 06/14/2018 Page 12
1 Oh, and just -- I don't know if I had
2 mentioned it or not, but groundwater flow
3 typically is going to be in a northwest
4 direction, so that would be from right to left
5 on the screen.
6 Why is it a problem? Well -- the PCE
7 and TCE in soil, why is that a problem? Because
8 it's leaching the groundwater and because it1s
9 caused vapors inside, you know, the main
10 building. It's not that, necessarily, those
11 contaminants in soil themselves, like just
12 touching the soil, is an issue. It's the fact
13 it's causing groundwater contamination and
14 they've contributed to the vapors in the
15 building.
16 And why are those contaminants an issue
17 in groundwater? Well, because groundwater is an
18 important source of drinking water. And the
19 concentrations at the site exceed our typical
20 cleanup levels for groundwater. And it's EPA's
21 policy to try to restore groundwater to its
22 beneficial use whenever possible. And the
23 beneficial use in this area is as a drinking
24 water source.
25 And why are these a problem in indoor
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1 air? Well, again, it's the concentrations that
2 we measure that exceeded our typical cleanup
3 goals. And one thing I really want to point out
4 though, is that, you know, we've taken a
5 short-term action to deal with the vapors in the
6 building. So for now, it's not an issue. It's
•7 just more about the long term, you know.
8 We installed a short-term solution back
9 in 2015, a fairly simple system. You just put
10 in a sub-slab ventilation system. But it does
11 the trick in terms of reducing the
12 concentrations in indoor air.
13 As part of the remedial investigation,
14 they do a human-health risk assessment and an
15 ecological risk assessment, and it just goes
16 through greater detail about how we calculate
17 potential risks for either carcinogenic or
18 non-carcinogenic health effects.
19 And you look at the lack of routes
20 exposure, you know, whether you're drinking the
21 water or breathing the vapors, digging in the
22 dirt -- and, usually, you're talking about
23 exposure over the long term, you know, number of
24 years.
25 As far as the ecological risk
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1 assessment, you know, this really isn't an
2 issue, you know, for wildlife. That's not a
3 driver here. It's really more about cleaning up
4 groundwater and reducing those vapor
5 concentrations.
6 We looked at different cleanup
7 alternatives. And what we did was we looked at
8 cleanup alternatives for, like, different depths
9 or zones. And the first zone we looked at was
10 the unsaturated soil zone. This is anywhere
11. from 0 to 50 feet below grade. And we look at
12 different alternatives. And we always consider
13 a no-action alternative, you know: If you did
14 nothing, you know, what would happen?
15 And then, you know, these are other
16 alternatives we looked at, you know. The
17 different types of treatment. Soil-vapor
18 extraction is like a tried-and-true method for
19 dealing with these kind of contaminants in soil.
2 0 You could do some soil excavation. It
21 wouldn't be very cost efficient to do that,
22 particularly the depths that we're talking
23 about. It's not very practical. And you could
24 also do in situ methods where you're injecting
25 chemicals that will break down the contaminants.
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1 In the saturated zone, or the shallow
2 groundwater, you know, we're talking roughly 50
3 to 80 feet below grade. You know, we looked at
4 a range of alternatives. Groundwater pump and
5 treat or groundwater recovery and treatment, you
6 know, that's a tried-and-true method. ISCO is
7 in situ chemical oxidation. That's actually
8 becoming more common.
9 In situ bioremediation. You know,
10 there are bacteria in the ground that can
11 dissolve some of these contaminants, and you
12 just do things to make the bacteria happier:
13 Give them more food, maybe more -- better
14 circulation of contaminants.
15 And then also the last one, it's a
16 version of an in situ remedy. This last one,
17 the acronym is BiRD. It's a little bit more
18 elaborate in the sense that you have pumping
19 wells and you're establishing like a
2 0 recirculating pattern in groundwater.. You're
21 encouraging, like, an indirect bacterial action.
22 You're setting up reducing conditions,
23 which forms some minerals that react with the
24 contaminants, to produce some inert compounds.
25 You'll also get some biotic degradation or
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1 bacterial degradation, but it's more about an
2 indirect approach.
3 And then the last segment that we
4 looked at was the dilute plume, which is the
5 groundwater that's a little bit deeper and it's
6 moved a little further off of the Walker Machine
7 property site itself.
8 And with that, you know, we looked at a
9 groundwater pump and treat. We looked at just
10 monitoring that until attenuation. We looked at
11 enhanced in situ bioremediation where you're
12 using barrier wells that you install along the
13 property line and then also a horizontal well,
14 which would be installed under the adjacent
15 property. And that is a delivery method.
16 Again, it's about making the bacteria
17 happy. So the injection is something innocuous.
18 It would be something -- think, like, vegetable
19 oil. I've seen a site where they have used
20 molasses as the food source for the bacteria.
21 Naturally, there are costs associated
22 with all of these remedies. We break them down
23 into cost for, you know, building it, cost for
24 running it, and then, trying to estimate how many
25 years it might run, and then come up with a
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1 present work cost so we can, compare them.
2 ' For the unsaturated zone, you know, the
3 0 to 50 feet of soil, the cost range the
4 active remedies range anywhere from 2.9 to 6.2
5 million, which assumes, like, an extensive area
6 under the building and then on the south side of
7 the building.
8 For the saturated zone, costs range
9 anywhere from 1,6 million to 4.5 million. The •
10 most expensive for the saturated zone was the in
11 situ chemical oxidation, you know. The cheapest
12 was the groundwater pump and treat.
13 ¦ For the dilute plume, the cheapest
14 thing is natural attenuation where, you know,
15 you're just establishing a monitoring program
16 for the long term and letting natural processes
17 take care of the contamination. The most
18 expensive was the enhanced in situ
19 , bioremediation !at about 2.5 million.
20 Hey, Randy.
21 MR. BRYANT: How are you doing?
22 Y'all can start now.
23 MR. BRYANT: Well, you are here at the
24 right time because we•re talking about preferred
25 alternative.
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1
Can you go back one?
2
Ml.' BRYANT: Sure.
3
Please.
4
MR. BRYANT: Yeah.
5
Now also, too, the fact sheet in the
6 back has a website for the Walker Machine
7 Product site, and it has, you know, the fact
8 sheet. And then it also has a little more
9 lengthy proposed plan, and it will have this
10 information in at as well.
11 • MS. COLEMAN: And also here at the
12 desk.
13 MR. BRYANT: That's right. You know,
14 another thing that we do is we compile a series
15 of documents for all these sites called the
16 administrative record, and it just encompasses
17 all the things we -- documents we relied on to
18 make our decision. So it includes the major
19 studies, like the remedial investigation, the
20 ' risk'assessment, the feasibility study.
21 And the administrative record is stored
22 here in the library, and it's on a CD. So you
23 need to go to the information desk and ask for
24 it. But there's always an administrative record
25 at a local, library for these sites.
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1 The purpose of coming out with proposed
2 plans is to tell you what we want to do, what we
3 think is the best approach, and we call it our
4 preferred alternative. And for the unsaturated
5 zone, we want -- we're proposing thermally
6 enhanced soil vapor extraction. There's a
7 little bit of air sparging,"which is actually a
8 groundwater piece, but that is extremely very
9 focused.
10 Basically, if -you think back to that
11 figure that had the red dot where you had the
12 highest concentrations and those couple of
13 monitoring wells that were on the south side of
14 the property, that's kind of the area where you
15 do a little bit of air sparging. But mainly,
16 this is about 0 to 50 feet soil contamination.
17 Soil vapor extraction will work, but it
18 may not get you all the way without doing
19 something to speed it up, and that's what the
20 thermal enhancement is about. There are
21 different ways to do it.
22 We're thinking thermal conductive
23 heating, which is basically putting in heater
24 wells. . They heat the soil up enough to where
25 the contaminants will volatilize a little bit
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1 more off soil. The soil vapor extraction system
2 can be more effective at sucking them out.
3 It is possible that we could go in and
4 do a little more sampling, be a little more
5 specific about design. And we may determine
6 that we don't have to do the thermal. But we
7 wanted to include the thermal now so we could
8 kind of present, you know, the most extensive
9 or -- like, the worst-case method that we would
10 have to take. And then we can always pull that
11 back if we don't actually need it.
12 But for now, we're planning on having a
13 thermal component to speed up or make the soil
14 vapor extraction more effective. There would be
15 a very limited amount of soil excavation
16 associated with this because there's like a --
17 there's a little spot just on, like, the south
18 side of the building where historically there
19 must have been a discharge because we see from
2 0 oils -- like you have cutting oils from the
21 operation.
22 And, historically, you had some higher
23 hits of TCE in the soil gas. So it's a limited
24 amount of excavation. It's a minimal component
25 to this. The big thing, though, is the soil
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1 vapor extraction. Because, again, you're going
2 to have to do it kind of like in the back woods,
3 and you'll have to try to get under the building
4 some.
5 And you can do that, you know, from --
6 you can work from the edge of the building and
7 go under, either directional drilling or an
8 angled boring. But we do need to try to go
9 under the building to get out some of the
10 contamination.
11 For the shallow groundwater, it's the
12 BiRD remedy. And that was the biogeochemical
13 reductive dehalogenation. And that's -- again,
14 that is where you have a recirculation system
15 going on. You're kind, of moving the groundwater
16 around. You're adding the carbon source to make
17 the bacteria a little bit happier to produce
18 reducing conditions to get the mineral formation
19 going to break down the contaminants.
2 0 And then for the dilute plume, we are
21 proposing the enhanced in situ bioremediation.
22 And that is straight up injection wells and just
23 adding the carbon source, like vegetable oil.
24 This slide gives you an idea of what
25 we're looking at for the unsaturated zone. If
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1 we had to do it everywhere, under the building
2 and then in the back woods on the site, all
3 those green circles that you see would be the
4 areas where you have a soil vapor extraction
5 well at the center of those points.
6 Now, it's much more realistic that
7 we'll just be able to focus back here and also
8 some maybe in the last third of the building. I
9 really don't think we'll need to go all the way
10 up to the front of the building. But this,
11 again, is kind of generally trying to present
12 the worst case, the most extensive scope of the
13 remedy.
14 This configuration shows you what we're
15 talking about with the BiRD method for the
16 shallow groundwater. It gives you an idea of
17 the injection points. The blue dots and then
18 the red and whit§ hatches, those are
19 recirculation wells.
20 Again, it's all about moving
21 groundwater, getting good contact with the
22 injective that you've added, which is vegetable
23 oil, and getting the proper conditions to get
24 the reaction that you want. And that just gives
25 you an idea of how we -- at least right now, of
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1 what we estimate we'd have to have in terms of a
2 network for the wells.
3 And the last piece is for the dilute
4 plume. Let's see. If I'm not in your way, this
5 would be our line of barrier wells where we're
6 doing injection. And then this would be, you
7 know, the estimated location for the horizontal
8 well under the adjacent building.
9 And, again, this is all about adding a
10 vegetable oil or similar material just to
11 encourage the bacteria to break down
12- contaminants. And that works a little bit
13 better when you're looking at -- or at least
14 it's a more effective way to deal with some of
15 these lower-level concentrations as opposed to
16 the higher stuff that we were seeing back here,
17 you know, directly south of the building back
18 here.
19 Okay. We've hit these points
20 (indicating). We've talked about that. This is
21 about (indicating), you know, the BiRD process
22 and the EISB approach for the dilute portion of
23 the plume.
24 One thing I want to emphasize is that
25 we can do this in pieces. It really lends
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1 itself to doing it in pieces. We can focus
2 first on the unsaturated zone, you know, the
3 shallow soil because that's, you know, that's
4 the source area that feeds the groundwater
5 contamination.
6 We can do that piece, see what kind of
7 impact that has on the groundwater quality. And
8 then we could do the shallow groundwater on-site
9 as necessary. And then if we had to do the last
10 piece, we can.
11 Again, this -- I've put it all out
12 there on the table for what all possibly could
13 be done. I want to do it in pieces, though, and
14 start with on-site with the highest
15 concentrations of contaminants in the source
16 area. And then we expect that that will start
17 improving groundwater quality.
18 So we may not have to do the last step,
19 very possibly the second step. But, again, it
20 will depend on timing and funding. And we'll
21 start on-site with the source contamination.
22 If we did all three pieces, you know,
23 we're looking at over $11 million as far as a
24 cost estimate. We won't get that kind of money
25 up front, and we don't need to spend that kind
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1 of money up front, you know. We'll focus again
2 on-site and do it in chunks.
3 We work with TDEC on the different
4 studies that have been done and discussions of
5 the different alternatives, and they're on
6 board. And it's important to have the state on
7 board because even though the federal government
8 is paying the vast majority of the cost, but as
9 a fund lead project, the state has to kick in 10
10 percent.
11 And just in terms of where we go from
12 here, the comment period will close, you know,
13 roughly in mid-July. We'll consider the
14 comments, see if we need to make any changes.
15 We prepare the responsiveness summary and then
16 go on. And then the final decision is contained
17 in what's called a record decision.
18 Like, a proposed plan is just a
19 condensed version of the record decision, and it
2 0 should -- unless we have significant comments
21 otherwise, it will be a preferred alternative
22 that we've talked about. Hopefully, we'll be
23 able to have a final decision made by August of
24 this year. And if that's the case, then we can
25 move into the design phase of the remedy. And
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1 we could start that as early as September of
2 this year and finish it roughly within a year.
3 So I'm estimating right now that the
4 earliest we'd actually start with the cleanup
5 work is probably going to be March of 2020. And
6 for that first phase, you know, the unsaturated
7 zone shallow soil, you're probably looking at
8 least three years of treatment.
9 Kind of a big kicker, though, is the
10 availability of funding. It will be relatively
11 easy to get funding for the design, you know.
12 This site will be a higher priority for cleanup
13 just given the fact that it's, you know --
14 proximity to the wellfield. But it does go
15 through our prioritization panel every year.
16 So you just it competes with other
17 sites across the country in terms of getting
18 funding. But we should be able to get at least
19 part of the funding and get part of the work
20 started. But, again, that's just -- that's a
21 little bit out of my hands.
22 And just a reminder, you know, this is
23 the comment period. There are different ways to
24 submit comments. They're printed on the fact
25 sheet and they're up here -- e-mail, regular
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'1 mall, phone calls. We have the transcript from
2 the meeting tonight. And then this is just our
3 contact information, which you should have in
4 various forms back there on the back either on
5 our business cards or on the fact sheet.
6 . And that's what I wanted to talk about.
7 That's kind of -- I hit all the high points. I
8 don't know if y'all have questions* particular
9 questions that we need to talk about now, or you
10 can call me later if you think of something
11 else.
12 But this is -- that's the crux of the
13 information that I have for you tonight. Again,
14 you can always look for the fact sheet if you
15 want to read a little bit more.about it
16 yourself. You could look at the documents in
17 the administrative -record if you really want to
18 get into, you know, all the details and see all
19 the work that went into getting to this point.
20 • But otherwise, like I say, I will take
21 questions now.
22 * Yes.
23 If I understood correctly
24 when you were doing the timeline
25 MR. BRYANT: Yeah.
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1 ~~ ^°U W0re talkin9 about
2 what I've noted as the fixst stage of three
3 stages. Is that correct or - -
4 MR. BRYANT; As far. as the remedy, yes,
5 Yeah.
6 MR. BRYANT; There are three pieces.
7 So when at the earliest,
8 let's say, that the saturated -- the second
9 phase, when would that be after the first phase?
10 MR. BRYANT; Well, let's say, just for
11 rough estimates right now
12 Yeah*
13 MR. BRYANT: -- if I started m '20 and
14 then finished in *22, it would probably be even
15 later in 22 or '23 before we got into the
16 shallow groundwater piece.
17 okay, And so where does
18 that leave step three?
19 MR. BRYANT: Then that would probably
2 0 be a similar time frame because I would think
21 that would probably be another several-year
22 iteration for doing the, you know, the BiRD
23 remedy for the shallow groundwater. So that
24 would probably be another three to five years.
25 So that puts us out -- what? --8 years before
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1 we decided that we had to do the dilute plume.
2 Now, what will happen, though, is, you
3 know, we'll be doing groundwater monitoring all
4 along once we get started. And we can see. how
5 things are improving or not improving and, you
6 know, that will affect our timeline. But that's
7 what I'm thinking in terms of those three steps
8 and that kind of rough schedule.
9 MR. WOODS: Hey, Randy, I just want to
10 interject. This is a remedy that we've used,
11 the Memphis Defense Depo, and it's a very
12 aggressive remedy. And we won the national
13 cleanup award there in 2010 using this remedy.
14 So if all goes according to plan, like
15 Randy insinuated, you know, the first phase may
16 be all that's required. We may not even have to
17 get to phase 2 and 3 if the aggressive remedy on
18 the front end handles the groundwater -- handles
19 the source and handles the groundwater as it
2 0 leaves the site, you know. Phase 2 may not even
21 be necessary, best case scenario.
22 But, again, this is a very aggressive
23 remedy. And, again, that's the reason the
24 thermal component was added, to speed it up.
25 Typical a thermal -- a typical SVE and the
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1 geologic setting here is a five-year operation.
2 A thermal component, you can get it down under a
3 year.
4 So, again, we'll have to evaluate it as
5 we go forward depending on how groundwater
6 responds. But this is a tried-and-true remedy
7 in this area. It's been very successful and
8 very aggressive.
9 Sorry.
10 MR. BRYANT: No, that's fine. I
11 appreciate it, Jamie.
12 MR. WOODS: Uh-huh.
13 MR. BRYANT: Yeah. So, yeah, when we
14 do that piece, that's probably the most
15 single -- single most expensive piece if we have
16 to do it as aggressively as we think that we
17 will. Because that was for the thermally
18 enhanced SVE, you know. That was a little over
19 6 million alone. And even that can be broken up
20 into pieces.
21 Because we can do certain parts in the
22 backyard. And just a little bit of that --
23 maybe that southern third of the building, that
24 may be enough. It's the kind of thing that
25 lends itself to scaling up. You get part in and
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1 you get it running. If you need to, you just
2 add more extraction wells. It kind of lends
3 itself to ramping up.
4 But it is still more expensive by far
5 than, the other remedies, but it's just one that
6 we think would be the most effective and one
7 ' that doesn't involve trying to dig it -all up.
8 Because if you have contamination soil that goes
9 as far as 40, 50 feet, it's just not really
10 practical to dig that far. I mean, a' practical
11 limit of excavation is probably 20, 25 feet
12 realistically.
13 And, again, this is not -- it's not
14 like you just have solid, uniform contamination
15 throughout like on the south side of the
16 building. You•11 have some --a little spot
17 over here and have a little spot over here. And
18 digging up a bunch to get out a little bit of
19 contamination just doesn't really make a -- it's
20 not the most cost-effective way to go about it.
21 . And it's not your imagination. It is
22 really warm in here. The library staff had told
23 me that their AC is not working very well today,
24 so --
25 ¦¦¦¦¦& well, we've got a tight
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1 budget in Collierville now.
2 I was going to ask if
3 they paid the utility bill.
4 MR. BRYANT; i There is a water fountain
5 out there. And if you need to get a drink, you
6 know, feel free.
7 He brought up the army depo.
8 That was very interesting.
9 MR. WOODS: Yes, sir. We've spent
10 about $75 million on that one to date, so it1s
11 been a long-term cleanup. But our last phase of
12 it, again, in 2010, it was done within a year.
13 And that was the main disposal area. We had
14 estimated it between 13 and 14,000 pounds, and
15 the source area, which is 0 to 30 feet, and it
16 was knocked out in six months. And the plume
17 dropped from about 15,000 part per billion.
18 Within a year, it was down to around 200 part
19 per billion.
2 0 Right.
21 MR. WOODS: So if you cut the head off
22 the dragon, essentially the tail dies pretty
; 23 quickly around here. We have a - - our geologic
24 setting here, we have 30 feet of silt. It's a
25 very tight, fine grain material that sits on top
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1 of everything and holds these sources of
2 contamination for long periods of time. So
3 that's why we're going to be aggressive in
4 attacking the source here.
5 Because if we 1 re aggressive on the
6 front end with the source, it definitely
7 shortens the groundwater cleanup portion of it.
8 And, you know, that's where all of the
9 uncertainty is, in the groundwater. I mean, the
10 source is one thing, you know, 0 to 30 feet, but
11 once you get beyond that, like Randy's saying,
12 there¦s a lot of uncertainty and it1s hard to
13 implement remedies at deeper zones. So a little
14 background there.
15 And I'm local, and I'm the Defense
16 Depot project manager. My card's back there if
17 you'd like to give me a call or reach out. I'm
18 here, too, so feel free.
19 MR. BRYANT: And then just one other
20 thing is, as Jamie had mentioned as a point of
21 reference, you know, I've been a very big
22 picture in terms of describing the issues at the
23 site, but if you're into numbers and want to
24 think about, you know, the level of contaminants
25 in groundwater -- like the PCE in groundwater,
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WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
Public Meeting on 06/14/2018 Page 34
—— 7" 1
1 the highest concentration that we see in
2 groundwater is from monitoring wells south of
3 the building on-site.
4 And those were like 2500 parts per
5" billion. And compare .that to a drinking water .
6 standard, and it's 5 parts per billion. So it's
7 quite a bit above what would be, you know, a '
8 drinking water standard and what we're using as
9 our cleanup goal for the groundwater.
10 As you go just onto -- just onto the
11 next property, we have more monitoring wells.
12 It drops down to about 800 or 900 parts per
13 billion. And as you continue going further
14 towards the intersection of, say, East Lee
15 Street and Washington, the monitoring wells
16 there were basically non-detect.
17 And that kind of goes back to that
18 figure that was up there earlier that showed
19 the, you know -- like the purple ring showing
20 the extent of groundwater contamination.
21 So where do the vapors go
22 if you start the extraction process in the soil?
23 Obviously, you're doing air quality testing
24 right now. You've got vapors in the building.
25 So you start extracting the site and you're
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WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
Public Meeting on 06/14/2018 Page 35
1 ' increasing the amount of, vapors.
'2 I'm just trying to -- I'm saying it out
3 loud so that I can. understand this myself, so --
4 MR. BRYANT: They --
5 Yeah. So the vapors are
6 now,, you know, coming out at an increased rate
7 under the ground to try and clean it up.
8 MR. BRYANT: Uh-huh.
9 So where do they go?
10 MR. BRYANT: They go -- typically, they
11 go into what's called granular activated carbon
12 or some other kind of filter
: Okay.
14 MR. BRYANT: you know, to capture
15 the vapors.
16 Okay. .
17 MR. WOODS: And as Randy alluded to, we
18 had hits inside, but after we installed the
19 sub-slab vapor depressurization, the hits
20 dropped off
21 - Okay.
22 MR. WOODS: And I think we had one that
23 was of concern after we saw the SV or the
24 sub-slab ventilation, so --
25 MR. BRYANT: Yeah, but that even
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WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
Public Meeting on 06/14/2018 Page 36
1 even that one dropped over repeated sampling and
2 got down to, you know, below our cleanup goals.
3 *
4 MR. BRYANT; Yeah, So it was
5 worthwhile to make sure you understand that at
6 the moment, you know, the site is under control,
7 - When we talk about these cleanup alternatives,
8 you know, we're talking about just making sure
9 that, you know, future problems don't get out of
10 hand. That's what that's about. But, you. know,
11 the situation is, like, under control now.
12 But let's just say, you know, the
13 current occupant of the building left and it sat
14 vacant -for a couple of years and the sub-slab
15 system wasn't running, then the vapors in the
16 building might increase again, And if you
17 didn't do anything with the stuff in the soil,
18 you know, the concent rat ions leaching into
19 groundwater may increase.
20 We don't know that they will. it could
21 be that we've seen the worst. Maybe we've seen
22 the worst and, you know, we'11 be happy about
23 that. But if we don't do anything, it¦s
24 possible that they could increase and
25 groundwater contamination could spread a little
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WALKER MACHINE PRODUCTS, 1.NC. SUPERFUND SITE PROPOSED PLAN
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1 bit further, and we don't want that to happen.
2 We want to go ahead and get a handle on it.
3 But, again, it's -- no one's drinking >
4 contaminated groundwater because there's nobody
-5 who has a private well on the property. This is
6' more about just preventing future issues,
7 we enc* UP moving on to
8 phase 2, what are the byproducts? I know we're
9 using bacteria, but everything produces waste.
10 MR. BRYANT: Well, the good thing --
11 depending on the particular species of bacteria,
12 I mean, there1s some bacteria that are really
13 good about converting it to relatively inert
14 compounds.
16 MR. BRYANT: A normal breakdown of PCE
17 and TCE to vinyl chloride is not the preferred . *
18 route. But there are bacteria species that can
19 break it down, making it avoid generating vinyl
20 chloride at all and that can produce ethene and
21 much more inert stuff. And it tends to be very
22 • localized where the bacteria are. •
23 Okay.
24 MR. WOODS: And, typically, once your
25 supplemental food source is used up, you'll see
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WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
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1 the rebound, you know, for your solvent in your
2 groundwater then. So that»s a signal we need to
3 . do more injection or whatnot.
4 MR*. BRYANT: Yeah, That's something
-5 you can revisit if you need to. You can always
6 add more injections later.
7 fljflBflf When-did it pop'up on
8 y*all's radar?
9 MR. BRYANT: Well, you go through
10 various steps. And I think you had some --
11 first investigations dating back probably to
12 2011. 'And what happens when we do these
13 various --we call it site assessment.
14 And it•s it will tend to be a few
15 samples trying to get an idea of if it's like a
16 really bad problem or something' that's not as
17 urgent. So you kind of go through different
18 steps, like a site assessment. But I think that
19 would go back as far back as 2011.
20 We -- it was like an initial site.
21 They call it, 1ike, a site investigation. And
22 then there's like an expanded site
23 investigation. And then you go on to proposing
24 it to the NPL. And this was actually finalized
25 on the NPL in 2014. And then later that year is
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1 when we started the remedial investigation,
2 which is a much more detailed sampling effort.
3 MR. WOODS: And 1*11 add to that. A
4 lot of these sites around in the Collierville
5 area, we don't have what we call the "confining
6 unit." Basically, once you get east of Byhalia
7 Road here, you're confining unit, your clay that
8 protects your aquifer like we have in Memphis,
9 is absent.
10 So, basically, if we even see
11 groundwater contamination shallow in the 50- to
12 60-feet range, we know there's no confining unit
13 there, so it's basically going into the Memphis
14 Sand recharge. So these out here score on
15 potential.
16 I mean, again, Randy insinuated we had
17 a hit at the water plant, but it's not
18 significant, and we're not even sure it's coming
19 from Walker to be honest. And once it's
20 aerated, it's non-detect.
21 So that's not the issue. We're not,
22 you know -- it's not a direct exposure where
23 people -- this is scoring on potential. And
24 that's why we're, you know -- why it was
25 evaluated. And more or less, why it goes to the
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WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
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1
NPL is all on potential. It's not on observed
2
or direct
releases
or impacts to, you know, the
3
public and their potable supply.
4
MR. BRYANT: Okay. Well, I mean, if
5
that's it
, I mean,
then we're done. I'm --
6
Could you start over?
7
MR. BRYANT: I'll send you some
8
CliffsNotes.
: Is your PowerPoint
9
10
available?
11
MR. BRYANT: It probably is. It's just
12
that there's like
a little bit of a process --
13
: Okay.
14
MR. BRYANT: -- that I need to do to,
15
like, release stuff.
16
: Got it.
17
MR. BRYANT: But, if you will, send me
18
an e-mail
•
: Okay.
19
20
MR. BRYANT: If you would do that, that
21
would help.
: All right.
22
23
MR. BRYANT: But, you know, thanks for
24
coming out. If you haven11 grabbed any stuff
25
off the back table
, feel free. And, again, you
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1
know, there's various contact information for
2
either -- for me or Kerisa if you have questions
3
after tonight.
4
And even though the comment period
5
ends, you can always call still with questions
6
and just check on status and see how things are
7
going. But thanks again for coming out.
8
MR. WOODS: Thank you, guys.
9
(Meeting concluded at 6:45 p.m.)
10
11
12
13
14
15
16 .
17
18
19
20
21
22
23
24
25
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WALKER MACHINE PRODUCTS, INC. SUPERFUND SITE PROPOSED PLAN
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1 STATE OF TENNESSEE )
) ss
2 COUNTY OF SHELBY )
3
4 I, Constance Simpson, Licensed Court
Reporter and Notary Public, Shelby County, Tennessee,
5 CERTIFY:
6 1. The foregoing was taken before me at the time
and place stated in the foregoing-styled cause with
7 the appearances as noted;
8 2. Being a Shorthand Reporter, I then reported the
trial in Stenotype to the best of my skill and
9 ability, and the foregoing pages contain a full, true
and correct transcript of my said Stenotype notes
10 then and there taken;
113. I further certify that I am not of counsel or
attorney for either or any of the parties to the case
12 named in the within caption, and that I am not
related to any party thereto.
13
IN WITNESS WHEREOF, I have hereunto affixed
14 my signature the 26th of June, 2018.
is IL (AurvjjsCu^
17 Constance Simpson, LCR
Licensed Court Reporter #642
18
19
20
21
22
23
24
25
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Walker Machine Products
Record of Decision
2018
APPENDIX B
STATE OF TENNESSEE CONCURRENCE
-------
STATE OF TENNESSEE
DEPARTMENT OF ENVIRONMENT AND CONSERVATION
Division of Remediation
William R. Snodgrass TN Tower
312 Rosa L. Parks Avenue, 14th Floor
Nashville, Tennessee 37243
September 13, 2018
Franklin E. Hill, Director
Superfund Division
US EPA - Region 4
Sam Nunn Atlanta Federal Center
61 Forsyth Street, SW
Atlanta, GA 30303
Subject: Record of Decision Concurrence Letter
Dear Mr. Hill,
The Tennessee Department of Environment and Conservation (TDEC) Division of Remediation has
reviewed the June 2018 Draft Record of Decision (ROD) submitted by the United States
Environmental Protection Agency (EPA) and concurs with the Selected Remedy, and with the phased
implementation of these components, as outlined in the ROD. It is our understanding that additional
site characterization will be conducted during the Remedial Design to verify the need for and to
optimize the design and extent of specific remedial actions.
This concurrence letter does not obligate the State to a State match or other obligations required
through a Superfund State contract (SSC). Those obligations can only be made through a SSC signed
by the State officials required to obligate the State of Tennessee.
If you have any questions, please feel free to contact me at (615) 532-8599 or
Chris.P.Thompson@tn.gov •
Walker Machine
EPA ID # TNN000410124,
TDEC/DOR ID #79-845
Sincerely,
Chris P. Thompson
Director
Division of Remediation
cc: DOR/NCO
DOR/MEFO
-------
Walker Machine Products
Record of Decision
2018
APPENDIX C
SELECTED REMEDY DETAILED COST ESTIMATE SHEETS
-------
Feasibility Study Cost Estimate
TEfldlGEGSSsa!
CtagaSB
Qggflliim
CteSaSGtasa
TfocftlinCTffifcrai
flffEma&SGt
Walker Machine
Collierville, TN
FS
CteggasKtonCajs
5333
UZWb UZ Alternative #2b
Thermally Enhanced SVE w/Umited Air Sparge
49072
1/15/2018
fta'fcffarv
2015
0
$6,261,300
Installation of "63 heater borings and 6 temperature monitoring points for thermally enhancing SVE. Installation
of "44 permanent air sparge wells on ~24-ft spacing* (~15-ft radius of Influence [ROI] assumed) to volatilize
organic contamination In the S5Z. Installation of "43 vertical and 10 angled permanent soil vapor extraction (SVE)
wells on **35-ft spacings (~20-ft ROI assumed) for direct extraction of CVOCi/VOCs/SVOCj. Recovered gases
treated with alr/fluid separation and vapor phase carbon.
fln-ftiitecft* Detailed estimate with subcontractor quotes (thermal vendor)
Volume of Impacted Media to be Treated w/SVE:| 104,815 |yd3 Unit Cost ($/yd3):^^
Materials/Equipment/ Subcontractors
36,257
4.0 Install Heater Borings and Temperature Monitoring Points
Drilling of (~63) heater borings to 55-ft bis. Drilling of (~6) temperature monitoring points to 55-ft bis. Well
development not required.
Drilling and Well Installation 1 Is S 543,663
$
5.0 Install SVE Wells-Vertical
Drilling of (43) 4-inch SVE wells to 50 bis with 45-feet screens. Assumes 2 wells drilled/day. Use 1 rig/day. 9 hr
day (22 days or ~4 weeks total). Well development not required.
6.0 Install SVE Wells - Angled and Laterals
Drilling of (10) 4-inch angled SVE wells (~45 degrees from vertical) to 50 bis. Total drilling 70-feet, with 45-feet
screens. Drilling of (2) 2" ~260-ft long horizontal utility bored vapor recovery wells 5-10 ft bis. Flush Mount.
Assumes 2 wells drilled/day. Use 1 rig/day. 9 hr day (5 days or ~1 week total). Well development not required.
60
1.0 Remedial Design/Bench Scale/Pilot Tests
Remedial Design Professional Labor
1
Is
$ 27,016
S
27,016
Remedial Design Travel
1
Is
$ 870
$
870
Materials/Equipment/Subcontractors
1
Is
$ 78,000
$
78,000
Bench Scale Testing
1
Is
$
$
-
Pilot Scale Testing
1
Is
$ 30,000
$
30,000
2.0 Mobilization/Demobilization of Equipment and Personnel
Mobilization/Demobilization of equipment and personnel (2/2 days)
Labor
Design/Bench/Pilot Testing Subtotal: $
1 Is S 21,788 $
135,886
21,788
Travel
1
Is
$ 6,053
$
6,053
Materials/Equipment/Subcontractors
1
Is
$ 139,380
?
139.380
Mobilization Subtotal:
$
167,221
3.0 Site Preparation '
Includes excavation of 1800 bey of DRO-impacted soil/TCE drum area/oil/water
separator areas; Utility
protection, grubbing, clearing, onslte meeting, materials (3 days);
Labor
1
Is
S
S
-
Travel
1
Is
$
S
-
36.257
Site Preparation Subtotal: $ 36,257
543,663
Thermal Well Subtotal: $ 543,663
Labor
1
Is
$
37,871
S
37,871
Travel
1
Is
$
9,158
$
9,158
Drilling Subcontractor Rate
2150
ft
$
60
$
129,000
Drilling Subcontractor - Other
1
Is
$
37,433
$
37,433
Well Materials
1
Is
s
94,275
S
94,275
Materials/Equipment/ Other Subs/Consumables
1
. Is
$
6,860
?
6,860
Vertical Extraction Well Subtotal: $ 314,597
Labor
1
Is
$ 6,949
$
6,949
Travel
1
Is
$ 2,163
$
2,163
Drilling Subcontractor Rate
700
ft
$ 60
$
42,000
Drilling Subcontractor - Other
1
Is
$ 7,775
$
7,775
Well Materials
1
Is
$ 28,250
$
28,250
Materials/Equipment/Subcontractors
1
Is
$ 24,200
$
24,200
Angled Extraction Well Subtotal: S
111.336
Page 8 of 39
-------
Qz&sa
Collierviife, TN
SBB1
UZ Hb
UZ Alternative t)2b
Thermally Enhanced 5VE w/Urnlted Air Spjqpt
7.0 install A!r Sparge Wells
Dniling of (44) 2-incti diameter air sparge wells. Drilling to 77-ft b'$ with 3-feet slotted screen. Flush Mount.
Assumes 2 wells drilled/day. Use 1 r>g/day. 9 hrday (22 days or~4 weeks total!.
8.0
Labor
1
Is
$
29,194
$
29,194
T'jvei
1
5
5,570
s
- 5,570
Drilling Subcontractor Rate
am
ft
$
56
s
177,408
Drilling Subcontractor - Other
i
Is
$
32,510
s
32,510
Well Materials
i
fe
$
36.386
$
36,385
Materials/Equipment/ Otner Suta/CoftfumsMei
i
li
$
14,251
$
14,251
Install Air Sparc Well Subtotal: $.
295,313
Install System PIp4nf/We)lheads
installation of 49 SVE weiltitwte, 44 (pu|i weflheaita, thermal weMeld plptag, heederi. lines,
abaveground piping
labor
i
k
$
235.246
$
235,246
Travel
i
k
$
42.883
' s
42,883
SVE Piping Installation Subcontractor
i
Is
$
90,700
s
90,700
Sparge Piping lista lation Subcontractor
i
Is
$
63,660
i
63,660
Install Piping/Wellheads Subtotal: $ 432,488
9.0 Construct/lrestai! SVE and Air Sparse Equipment Enclosure/System
Install SVE system (moisture separator, exhaust blower, vapor phase carbon, appurtenances), sir spargt
system [air compressor, appurtenances), and enclosure. Assume (2) trellered mobile
units in fenced
1
co-npound. Ten day installation assumed.
tabor
1 is
$ 88,270
$
&8.270
Travel
1 * Is
i 13,607
s
11.607
Site Preparation
1 Is
S 17,500
$
17,500
Extraction Wells and Sparge Wells Main Headers
1 *
$ 12,554
$
12,554
Equipment E-iclosure/SVE and Air Sparge Treatment System*
1 If
$ 146,400
$
146,400
SVE and Ai' Sparge Manifolds
1 U
S
s
SVE Wellhead Aisenbly
1 is
$
$
-
SVE/Sparge System Subtotal:
10.0 Con struct/Install Tlmnal Conduction Heating System
install thermal rend jrt on heating system (vapor cover, tSTD power equipment, treatment system, electrical,
Instruments and monitoring).
labor ' , 11$
Travel 1 h
Equipment and Ttierm®! Treatment System* 1 k
S 110,885
S 17.059
$ 298,535
TlWrmal System Stibtttttl:
278,331
$ 110,8&5
$ 17,059
$ 298,535
i «£d»
Pi«e 9 of 39
2/27/2018
-------
Feasibility Study Cost Estimate
Walker Machine
Collierville, TN
£ffians3fca<
UZMb
UZ Alternative «2b
Thermally Enhanced 5VE w/Umlted Air Spjige
__Cost ($).
11.0 Thermal System Startup and Operation
Pre-startup, shakedown, and operation of thermal treatment system for 200 days. Preparation of equipment,
materials, and labor for operation. Reporting.
Labor
1
Is
$
106,596 $
106,596
Travel
1
Is
$
19,404 $
19,404
Materials/Equipment/ Other Subs/Consumables
1
Is
$
916/450 $
916,450
Monitoring, Sampling, Analysis
1
Is
S
16,000 $
16,000
Thermal Operation Subtotal: $
1,058/450
Install Vapor Monitoring Points
Drilling of (6) 2-Inch diameter vadose zone PMWs for chemical and vacuum readings. Drilling to 50-ft bis with 45-
feet screen and 10-slot. Flush Mount. Assumes 2 wells drilled/day. Use 1 rig/day.
9 hr day (~3 days total).
Labor
1
Is
$
8,442 $
8,442
Travel
1
Is
$
1,983 $
1,983
Drilling Subcontractor Rate
300
If
$
56 $
16,800
Drilling Subcontractor - Other
1
Is
$
7,705 $
7,705
Well Materials
1
Is
$
10,217 $
10,217
Materials/Equipment/ Other Subs/Consumables
1
Is
$
5,540 $
5,540
Vapor Monitoring
Points Subtotal: $
50,687
Subtotal - Capital Costs: | $ 3,850,714
of Capital Cost
Capital Contingency
legal Fees, Licenses & Permits1
Engineering & Administrative1
Contractor Fee2
1 Applied to capital subtotal and contingency
2 Applied to capital subtotal, contingency, fees, and E&A
15%
0.5%
8%
10%
of Capital Cost
$ 577,607
$ 22,142
$ 354,266
$ 480,473
Total Capital Cost:
1$ 5.285,;
201
Page 10 of 39
2/27/2018
-------
Feasibility Study Cost Estimate
GteSass
Walker Machine
Collierville, TN
tffis
UZ»2b
UZ Alternative 02b
Thermally Enhanced SVE w/Umlted Air Sp<
M
| ©MKissas 1
Unit Cost • Note,, Cost {$f.
O&M Period
7.00*
0.00*
Discount Rate
Constant Escalation Factor
10.0 SVE and Air Sparge O&M Costs
Operation of SVE and air sparge systems for 5 years. Preparation of equipment, materials, and labor for
Annual Cost
operation. Assumes (1) staff full-time for first month then 6 hrs/week thereafter, plus (1) supplemental
staff as needed (~120 hr/year).
Labor 5
vr
1
total $ 41,931
$
41,931
Travel 5
V
1
total $ 11,250
$
11,250
Materials/Equipment/Subcontractors 5
Vr
1
total $ 45,380
$
45,380
Analytical - Soil S
Vr
1
total $
$
-
Analytical - Air Phase 5
Vr
1
$
S
-
$
98,561
11.0 Performance Sampling OftM Costs
Monitor system performance for VOCs and SVOCs (influent and effluent, each manifold [quarterly])
weekly first two months, bimonthly for 10 months, monthly thereafter (76 events); 9 hour day - 2 day
effort, 4 hr travel, 4 hr prep.
Labor 5
Vr
1
total $ 36,212
$
36,212
Travel 5
V
1
total $ 10,183
$
10,183
Materials/Equipment S
Vr
1
total S 3,983
$
3,983
Analytical 5
V
1
total $ 25,317
$
25,317
$
75,696
Net Present Worth (NPW) Subtotal: $
714,489
O&M Contingency
15%
of NPW Cost
$
107,173
Engineering & Administrative1
8%
s
65,733
Contractor Fee2
10*
s
88,740
'Applied to O&M subtotal and contingency
Subtotal - O&M Costs:
$
976,135
1 Applied to O&M subtotal, contingency, and E&A
Net Present Worth Formula
where:
P = Present Value ($)
Ao =' Annual Amount ($)
d = discount rate
e = escalation factor
n = time period (yrs)
Note: Net Present Worth derived from summation of Modified Uniform Present Value (UPV*).
= 1$ 6,261,:
Total NPW Cost Estimate:
300
Remedial Design/Bench Scale/Pilot Tests
Site Preparation
Install SVE Wells - Vertical
Install Air Sparge Wells
Construct/Install SVE and Air Sparge.
• Thermal System Startup and Operation
General Assumptions
1. Professional rates are averaged to reflect typical labor rates for personnel required for project.
2. Cost basis derived from professional judgment and experience unless specified directly.
3. Costs are derived to be (-30% to +50%)
Page 11 of 39
2/27/2018
-------
Feasibility Study Cost Estimate
ftfljflGKfflSsSS
Cteg&S
. nm^fflnTB
EteSssBCtea
¦vMiBsaftfflniB
ffrpnnfcgfoi
Walker Machine
Coiiierviile, TN
FS
fiteKSffiBa
TESsb
CtojJsSKliiiiQss
HEfia
SSZffS
SSZ Alternative #5
Blogeothemlcal Reductive Dehalogenatlon
49072
9/27/2016
[l&se'iteEra
QaiMkin
201S
1
$1,997,000
In situ treatment using naturally occurring divalent minerals along with supplemental Injectable carbon substrate,
sulfate, and soluble ferrous Iron in an Injection well array to facilitate direct chemical reduction of CVOCs in the
solvent source area using Iron sulfides.
Detailed estimate
- *• * 'QW*l w>.-U_nit W-^Uhit-Cost /-iNote ' Cost($) -
Volume of Impacted Media to be Treated with ISCR:| 15,111 ~|vd3 Unit Cost ($/yd>): 1$
1.0 Remedial Design/Bench Scale/Pilot Tests
3.0 Site Preparation
Utility protection, grubbing, clearing, pre excavation meeting, materials (3 days);
Labor 1 Is
Travel 1 Is
Materials/Equipment/ Subcontractors 1 Is
$ - S
S - $
$ 11,059 $
Site Preparation Subtotal: $
4.0 Install BIRD Injection Wells
Drilling of (27) 4-inch injection wells for BIRD. Drilling to 75-ft bis with 25-feet screens. Flush Mount. Assumes 2
wells drilled/day. Use 1 rig/day. 9 hr day (14 days total). Task includes well development.
5.0 Install EISB/ISCR Extraction/Reclrculatlon Wells
Drilling of (13) 4-inch Extraction Wells for BiRD. Drilling to 75 ft bis with 25-feet screens. Flush Mount. Assumes
2 wells drilled/day. Use 1 rig/day. 9 hr day (6.5 days total). Task includes well development.
Install Extraction Well Subtotal:
132
Remedial Design Professional Labor
1
Is
$
28,239 $
28,239
Remedial Design Travel
1
Is
$
870 $
870
Materials/Equipment/Subcontractors
1
Is
$
35,500 $
35,500
Bench Scale Testing
1
Is
$
18,000 $
18,000
Pilot Scale Testing
1
Is
$
35,000 S
35,000
Mobilization/Demobilization of Equipment and Personnel
Deslgn/Bench/Pilot
Scale Subtotal: $
117,609
Mobilization/Demobilization of equipment and personnel (2/2 days)
Labor
1
Is
$
44,975 $
44,975
Travel
1
Is
s
6,053 $
6,053
Materials/Equipment/ Subcontractors
1
Is
$
2,285 $
2,285
Mobilization Subtotal: $
53,313
11,059
11,059
Labor
1
Is
S
21,038
$
21,038
Travel
1
Is
S
4,811
$
4,811
Drilling Subcontractor Per/Foot Rate -
2025
Is
$
60
$
121,500
Drilling Subcontractor - Other
1
Is
$
23,430
$ •
23,430
Well Materials
1
Is
$
56,873
$
56,873
Materials/Equipment/ Other Subs/Consumables
1
Is
$
9,808
$
9,808
Install Injection Well Subtotal: $
237,459
Labor
1
Is
s
16,087
16,087
Travel
1
Is
s
3,117
3,117
Drilling Subcontractor Day Rate
975
Is
$
60
58,500
Drilling Subcontractor - Other
1
Is
$
14,085
14,085
Well Materials
1
Is
$
26,558
26,558
Materials/Equipment/ Other Subs/Consumables
1
Is
s
8,028
8.028
126,376
Page 30 of 39
-------
1,0
Walker Machine
Collterville, TN
SSZ «5 |
SSZ Attemativp «
ilBiogeochemlcal Reductive Pehalagenatlon
i.0 Install Extraction System Piping/Wellheads
installation of 13 «tr»etlon mH wwllheais;
Labor
Travel
Materials Equipment/Subcontractor
7.0 Construct/Install BIRD OctNcfy System
Install Hp&ig/WeBhtiitfe SidhtMsI* $
BIRD Delivery System Subtotal:
install Performance MonHorfrig Wei is
O-illing of (6) 2-inch diameter pe-fcrmanee monitoring wife (PMWs). OT#n»U> 75 ft Ms with 20-fwt scrten mi
lO-i tot. flush Mount. Assumes 3welbdrle#d»f,ystlfte/d«y. ® hr fey (1 days total), T«k Inclu'tles inell
9.0 Construct Infiltration Gallery
Install infiltration gallery; assume S dip; (aunt 40-ft by 75-ft by 3»fe«t deep
Infiltration Gallery Subtotal:
10.0 BIRD Injection and Initial Startup
Preparation of EtSB/ISCR solution, equipment, materials , and labor for injection services. Assumes (1 months)
of injection. Twoweelisoi manned operation followed iiv 2 additions' days/month (108 hrs), 9-hr days; All
chemical costs,
MS) Startup/Injection; $
1*
$
S05I7
$ .
30327
Is
$
6,275
S
6,215
Is
s
10,234
s
63,234
Instil BifiD system, light f8|
-------
m
Walker M»Chlre
CoUlerville, TO
smm
SSZ Alternative #5
Blogeothgrnlcal Reductive Dghatoggnaltwi
1»
2)
"""
3)
Siititcua)**Capita! costs*
i$
1,159,928
Capital Contingency
IS*
of Capital Cost
$
175,489
legal Fees, licenses ft Permits1
0.5*
$
6,727
Engineering & Administrative'
m.
$
107,633
Contractor Fee1
10*
of Capital tort
s
145,978
fetal capital Cost:
1$
"App ied to capita! subtotal and contingency
' Applied to capital subtotal, contingency, fees, and EM
PagtOof®
2/27/2011
-------
Feasibility Study Cost Estimate
(jteft&S
Walker Machine
Collierville,TN
SSZft5 |
SSZ Alternative #5
fittonSSsQCS
TTTTfeii Blogeochemlcal Reductive Dehalogenation
11.0 BIRD Year 1-3 Operation
O&M Period
7.00%
0.00%
Discount Rate
Constant Escalation Factor
Annual Cost
Recirculation/lnjection of amendments for BiRD; monitoring. Assumes (36 months) of injection,
operation of 4 days/month for 3 years ("432 hrs/yr); 9-hr days; assumes 25% more chemicals.
Manned
Labor
3 yr
1 total
. $
77,765
77,765
Travel
3 yr
1 total
S
24,971
24,971
Materials/Equipment/ Other Subs/Consumab
3 yr
1 total
S
6,388
6,388
DPT Injection Drilling Subcontractor
3 yr
1 total
S
-
-
DPT Vendor - Materials/Equipment/ Other
3 yr
1 total
S
-
-
Chemicals and Freight
3 yr
1 total
$
56,726
56,726
BiRD Startup/Injection:
12.0 Performance Sampling Costs
Gauge ~14 wells for field parameters and substrate/amendments weekly first month, quarterly for 4 years (20
events); 9 hour day - 2 day effort, 4 hr travel, 4 hr prep. Four days of DPT soil sampling.
Ao = Annual Amount ($)
d = discount rate
e = escalation factor
n = time period (yrs)
Note: Net Present Worth derived from summation of Modified Uniform Present Value (UPV*).
TI
165,850
Labor
4
yr
1
Is $ 36,237 $
36,237
Travel
4
yr
1
Is $ 5,100 $
5,100
Materials/Equipment/Subcontractors
4
yr
1
Is $ 12,910 S
12,910
Analytical
4
yr
1
Is $ 4,729 $
4,729
Sampling Subtotal: $
58,976
Net Present Worth (NPW) Subtotal: $
286,375
O&M Contingency
15%
of NPW Cost $
42,956
Engineering & Administrative1
8%
$
26,347
Contractor Fee2
10%
$
35,568
1 Applied to O&M subtotal and contingency
Subtotal - O&M Costs:| $
391,246
2 Applied to O&M subtotal, contingency, and E&A
Net Present Worth Formula
where:
P = Present Value ($)
Total NPW Cost Estimate:
Remedial Design/Bench Scale/Pilot Tests
Mobilization/Demobilization of Equipment
Site Preparation
Install BiRD Injection Wells
Install EISB/ISCR Extraction/Recirculation.
Construct/Install BiRD Delivery System
Install Extraction System Piping/Wellheads
BiRD Injection and Initial Startup
Construct Infiltration Gallery
Install Performance Monitoring Wells
D 0.9%
10.1%
4.6%
Capital Cost
Summary
3 10.8%
~ 17.4%
3 8.6%
] 3.4%
~ 3.9%
1,997,000
General Assumptions
1. Professional rates are averaged to reflect typical labor rates for personnel required for project.
2. Cost basis derived from professional judgment and experience unless specified directly.
3. Costs are derived to be (-30% to+50%)
Page 33 of 39
2/27/2018
-------
1.0 Remedial Deslgn/B«m:h Scale/Pilot Tests
Remedial Des'gn Professional Ukor 1
Is
$ 24,181
$
24,111
Remedial Des gn Travel I
Is
$ 870
$
870
Materlals/Equipment/Subcontractors 1
Is
• S 500
s
500
Bench Scale Testing 1
Is
. $
s
-
Pilot Scale Testing 1 *
Is
$ 25,000
?
25.000
Dsslgrt/Benth/P]lot Scale Subtotal:
$
50,551
2,o M^hflfT^frn/r^Tiobtifrrfflfm of Iq^fMncnt and Pfifsoitfiet
Moblllati0'i»/O«mobai»tion ofequipmant and panonnal (2/2 dayt)
labor , 1
Is
S 41,973
$
41,973
Travel I
Is
$ 6,053
$
6,053
M*terMi/EquIpment/ SubeantrMOfi 1
Is
$ 4.680
$
4,680
Mobilization Subtotal:
%
53,707
3.0 Site Preparation
Utility protection, grubbing, during, pee excavation meeting, materials (3 days);
labor 1
Is
s •
%
Trawl " 1
Is
$
s
Materials/Equipment/ Subcontractor! 1
Is
S 12,653
s
12,653
Situ Preparation Subtotal:
$
12,653
4.0 install EI5B Injection Weils
•
Drilling of (IS) 2-
-------
Feasibility Study Cost Estimate
IV.;^rtt;r.n
Walker Machine
Collierville, TN
fiftSCEEte©®
¦nfffla
DP #3 |
DP Alternative A3
EISB Passive Barriers w/Horlzontal Well
Unit Cost, Note,
6.0 Construct/Install EISB Delivery System
Install EISB/ISCR feed system. Eight (8) day installation assumed. Includes construction of aboveground or
permanent yard piping (4 days). Header by injection vendor.
Labor
1 Is
$
29,943
$
29,943
Travel
1 Is
$
7,171
$
7,171
Site Preparation
1 Is
$
18,904
$
18,904
Extraction Wells Main Header
1 Is
$
-
S
-
Water Treatment System
1 Is
$
14,000
$
14,000
Injection Manifold
1 Is
$
9,029
$
9,029
Injection Wellhead Assembly
1 Is
$
2,839
S
2,839
EISB Delivery System Subtotal:
$
81,887
7.0 Install Performance Monitoring Wells
Drilling of (4) 2-inch diameter performance monitoring wells (PMWs). Drilling to 75 ft bis with 25-feet screen and
10-slot. Flush Mount. Assumes 2 wells drilled/day. Use 1 rig/day. 9 hr day (2 days total). Task includes well
development.
Labor
1
Is
$
4,084
$
4,084
Travel
1
Is
$
1,340
$
1,340
Drilling Subcontractor Per/Foot Rate
300
days
$
56
$
.16,800
Drilling Subcontractor - Other
1
Is
$
4,680
$
4,680
Well Materials
1
Is
$
6,871
$
6,871
Materials/Equipment/ Other Subs/Consumables
1
Is
$
974
$
974
Install PMW Subtotal:
$
34,749
8.0 EISB Injection and Initial Startup
Preparation of EISB/ISCR solution, equipment, materials, and labor for injection services. Assumes (4) weeks of
injection. 2 days of setup/demobe.
Labor
1 ls
$
28,542
$
28,542
Travel
1 Is
$
10,992
$
10,992
Materials/Equipment/ Other Subs/Consumables
1 Is
$
88,719
$
88,719
DPT Injection Drilling Subcontractor
1 Is
S
-
$
-
DPT Vendor - Materials/Equipment/ Other Subs/Consumables
1 Is
$
-
$
-
Chemicals and Freight
1 Is
s
213,271
$
213,271
EISB Injection: $ 341,525
Notes:
Capital Contingency
Legal Fees, Licenses & Permits1
Engineering & Administrative1
Contractor Fee1
1 Applied to capital subtotal and contingency
2 Applied to capital subtotal, contingency, fees, and E8tA
15%
0.5%
8%
10%
Subtotal - Capital Costs: [ $ 1,055,049
of Capital Cost
of Capital Cost
Total Capital Cost:
$ 158,257
$ 6,067
$ 97,064
$ 131,644
1$ 1.448,1
.081
Page 38 of 39
2/27/2018
-------
O&M Period
7.00%
0.00%
Dfecount Rate
Constant Escalation Factor
9.0 ElSB Year 1-5 Operation
Reinject on of amendments for rebound, monitoring at S yr intervals for 20 years. Assumes (3096) of original
effon and time of operation.
JkEtttui! €®$t
Labor
15
V
i li
S
1,756
$
1,716
Travel
15
V
1 b.
S
706
s
706
Materia s/Fquipment/Other Subs/Consumab
15
V
1 Is
$
6,284
$
6,284
OPT Injection Drilling Subcontractor
15
w
1 IS'
5
.
$
.
OPT Vendor - Materials/Equipment/ Othe'Sd
15
V
x is
s
s
-
theftftak and Freight
IS
F
1 is
$
21,340
21,340
¥«
M 1 to 51KB Operation:
$
30,046
10.0 Performance Sampling Costs
Gauge ~8 wells for field parameters and subftratt/vrwrxbntnU quarterly each y**r (4 tvntt), f hour cy. and EfcA
a* * f |
TlwH" • WJ111|* 13
IS*
8*
10%
ofHfWCoct
$ 109,972
S 67,449
$ 91,05.7
SubMtal * MM Costs:| $ 1,001,623
f » Present Value ($)
Ao * Annual Amount ($)
d a discount rate
e = escalation latter
n = time period (yrs)
Note: Net Present Worth dertwj hm summation of Modifed Uniform ft*sent Value [UPV").
Total WW Cost Estimate: |$ ijmjW
Remedial Design/Bench Scale/Pilot Ton
JMBI 4J%
mmm s,ox
Capital Cost
Summary
Mobtliialiofl/OemeMliatai of Equipment
Site Preparat on
li ij*
Install ElSB Injection Wells
]¦¦¦¦¦¦¦¦¦ 12.9K
ton struct/Install I.SB Del.very System
¦MM 7JK
Instill Infraction System Plping/Wef (heads
1 0.0*
ElSB Year 1-5 Operat on
mm 2 jm
Instill Performance Monitoring Wells
Pwfofw«» Sampling Ce^s
pa ij*
jmm *.«
General Assumptions
1. Professional rates are averaged to reflect typical labor rates for personnel required for project.
2. Cost basis derived froni professional judgment jnd experience unless specified directly.
3. Costs are derived to be {-30% to ~50%)
Page 3$ of 39
2/27/2018
------- |