SDMS DOCID# 1153972
RECORD OF DECISION
for the
Boundary Operable Unit
OU-6
AEROJET SUPERFUND SITE,
RANCHO CORDOVA, CALIFORNIA
U.S. Environmental Protection Agency
Region IX
San Francisco, California
Final
EPA ID: CAD980358832
August 4, 2015
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FINAL
RECORD OF DECISION
for
Operable Unit 6
AEROJET SUPERFUND SITE,
RANCHO CORDOVA, CALIFORNIA
U.S. Environmental Protection Agency
Region IX
San Francisco, California
August 2015
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Table of Contents
Section Page
ACRONYMS AND ABBREVIATIONS v
PART 1: I I Ii: DECLARATION 1
1.1 Site Name and Location 1
1.2 Statement of Basis and Purpose 2
1.3 Assessment of Site 4
1.4 Description of Selected Remedies 4
1.5 Statutory Determinations 7
1.6 ROD Data Certification Checklist 7
1.7 Authorizing Signature 8
PART 2: I I Ii: DECISION SUMMARY 9
2.1 Site Name, Location, and Description 9
2.2 Site History and Enforcement Activities 35
2.3 Community Participation 39
2.4 Scope and Role of the Operable Unit or Response Action 40
2.5 Site Characteristics 41
2.6 Current and Potential Future Land Site and Resources Uses 60
2.7 Summary of Site Ri sks 71
2.8 Development and Selection of Remedial Action Areas 94
2.9 Remedial Action Objectives 119
2.10 Description of Alternatives 119
2.11 Summary of Comparative Analysis of Alternatives 127
2.12 Principal Threat Wastes 134
2.13 Selected Remedies 143
2.14 Statutory Determinations 145
2.15 Documentation of Significant Changes 147
PART 3: RESPONSIVENESS SUMMARY 149
3.1 Stakeholder Issues and EPA Responses 149
3.2 Technical and Legal Issues 149
Works Cited 151
Appendix A Groundwater Plume Maps from OU-5 ROD
Appendix B Summary of Remedial Action Areas
Appendix C Administrative Record Index
Appendix D Detailed Description and Cost Data
Appendix E Responsiveness Summary to OU-6 Proposed Plan Comments
Appendix F EPA Letter to Community Advisory Group (December 5, 2012)
ES042114142800SAC
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List of Tables
No. Title Page
2-1 Contaminants of Concern in Soil and Soil Vapor 42
2-2 Performance Standards for Soil 43
2-3 Performance Standards for Soil Vapor in Ambient Air 49
2-4 Noncancer Toxicity Criteria 75
2-5 Carcinogenic Toxicity Criteria 77
2-6 Summary of Risks from Exposure to Surface Water by Exposure Area 79
2-7 Summary of Risks from Exposure to Groundwater by Exposure Area 81
2-8 Summary of Risks from Exposure to Soil and Sediment by Exposure Area 83
2-9 Summary of Risks from Exposure to Soil Vapor by Exposure Area 85
2-10 SLERA Summary Table 91
2-11 Source Areas and Soil Remedial Action Areas 96
2-12 Comparative Analysis Summary for OU-6 128
2-13 Description of ARARs for Selected Remedies 135
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List of Figures
No. Title Page
2-1 Aerojet Superfund Site Map - Location 9
2-2 Location of Management and Open Space Areas, Boundary Operable Unit 13
2-3 Site Features Map, Administration Area East 15
2-4 Site Features Map, Administration Area West 17
2-5 Site Features Map, Line 2 Region 19
2-6 Site Features Map, Line 5 North 21
2-7 Site Features Map, West Lakes and Open Space Area 6 23
2-8 Site Features Map, Buffalo Creek 25
2-9 Site Features Map, Chemical Plant 2 27
2-10 Site Features Map, Magazine Area and Open Space 3 29
2-11 Site Features Map, Dredge Pit and Eastern Basin 31
2-12 Site Features Map, Open Space Areas 5, 6, and 7 33
2-13 Composite Plume Map, May 2014 37
2-14 Conceptual Site Model - Soil Exposure Pathways for Human Receptors 51
2-15 Conceptual Site Model - Groundwater and Surface Water Exposure Pathways for
Human Receptors 53
2-16 Conceptual Site Model - Soil Exposure Pathways for Ecological Receptors 55
2-17 Conceptual Site Model - Groundwater and Surface Water Exposure Pathways for
Ecological Receptors 57
2-18 Conceptual Model of Groundwater Structure 59
2-19 Ownership and Proposed Use at Aerojet 63
2-20 Current and Proposed Uses 65
2-21 Proposed Developments - Easton Place 67
2-22 Westborough Phase 2 69
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2-23 Remedial Action Areas for Administration Area East 101
2-24 Remedial Action Areas for Administration Area West 103
2-25 Remedial Action Areas for Line 2 Region 105
2-26 Remedial Action Areas for Line 5 North 107
2-27 Remedial Action Areas for Buffalo Creek and West Lakes Areas 109
2-28 Remedial Action Areas for Magazine Area/OS-3 and OS-4 Ill
2-29 Remedial Action Areas for Chemical Plant 2 and OS-1 113
2-30 Remedial Action Areas for Dredge Pit, Eastern Basin, and OS-2 115
2-31 Remedial Action Areas for Operable Unit 6 117
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Acronyms and Abbreviations
ฐF degree(s) Fahrenheit
|ig/dL microgram(s) per deciliter
|ig/L microgram(s) per liter
|ig/m3 microgram(s) per cubic meter
1.1-DCE 1,1-dichloroethene
1,1,1-TCA 1,1,1-trichloroethane
1,1,2,2-PC A 1,1,2,2-tetrachloroethane
1.2-DCA 1,2-dichloroethane
4,4'-DDD 4,4'-dichlorodiphenyldichloroethane
4,4'-DDE 4,4'-dichlorodiphenyldichloroethene
4,4'-DDT 4,4'-dichlorodiphenyltrichloroethane
Aerojet Aerojet Rocketdyne, Inc.
APN Assessor's Parcel Number
ARAR applicable or relevant and appropriate requirement
ARGET American River Groundwater Extraction and Treatment
AST aboveground storage tank
ATSDR Agency for Toxic Substances and Disease Registry
BEHP bis(2-ethyhexyl)phthalate
bgs below ground surface
BMP best management practice
BTEX benzene, toluene, ethylbenzene, and xylene
CAG Community Advisory Group
Cal-EPA California Environmental Protection Agency
CCR California Code of Regulations
CERCLA Comprehensive Environmental Response, Compensation, and Liability
Act
CERCLIS Comprehensive Environmental Response, Compensation, and Liability
Information System
CFR Code of Federal Regulations
ci s-1,2-DCE ci s-1,2-dichloroethene
CL cleanup level
COC contaminant of concern
COPC contaminant of potential concern
COPEC contaminant of potential ecological concern
Cr6 hexavalent chromium
CSM conceptual site model
d-BHC d-benzene hexachloride
DLM designated level methodology
DnBP di-n-butyl phthalate
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DSA
Drum Storage Area
DTSC
Department of Toxic Substances Control
EC
engineering control
EPA
U.S. Environmental Protection Agency
EPC
exposure point concentration
ERM
Environmental Resources Management
ESA
Endangered Species Act
ESL
ecological screening level
FS
feasibility study
FSP
field sampling plan
FSTP
former sewage treatment plant
FYR
Five-year review
GET
groundwater extraction and treatment
GIS
geographic information system
gpd
gallons per day
GW
groundwater
HEAST
Health Effects Assessment Summary Tables
HH
human health
HHERA
human health and ecological risk assessment
HHRA
human health risk assessment
HI
hazard index
HQ
hazard quotient
HVAC
heating, ventilation, and air conditioning
IC
institutional control
ILCR
incremental lifetime cancer risk
IRCTS
Inactive Rancho Cordova Test Site
IRIS
Integrated Risk Information System
LANL
Los Alamos National Laboratory
LUC
land use control
MA
management area
MCL
maximum contaminant level
mg/kg
milligram(s) per kilogram
MW
molecular weight
NC
no carcinogenic compounds of interest in a sample
NCEA
National Center for Environmental Assessment
NCP
National Oil and Hazardous Substances Pollution Contingency Plan
NDMA
n-nitrosodimethylamine
NO A A
National Oceanic and Atmospheric Administration
NPDES
National Pollutant Discharge Elimination System
NPL
National Priorities List
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O&M
operation and maintenance
OEHHA
Office of Environmental Health Hazard Assessment
ORNL
Oakridge National Laboratory
OS
open space
OU
operable unit
OU-3
Western Groundwater Operable Unit
OU-5
Perimeter Operable Unit
OU-6
Boundary Operable Unit
OU-7
Island Operable Unit
PAH
polycyclic aromatic hydrocarbon
PCB
polychlorinated biphenyl
PCD
Partial Consent Decree
PCE
tetrachl oroethene
PHG
Public Health Goal
ppm
parts per million
RAO
remedial action objective
RCRA
Resource Conservation and Recovery Act
RCRB
Redding-Corning-Red Bluff
RfD
reference dose
RI
remedial investigation
ROD
Record of Decision
RSL
Regional Screening Level
RWQCB
Regional Water Quality Control Board
SLERA
Screening-Level Ecological Risk Assessment
SMAQMD
Sacramento Metropolitan Air Quality Management District
SPCC
Spill Prevention, Control, and Countermeasures
SPZ
Special Planning Zone
SSD
subslab depressurization
ssv
subslab venting
SVE
soil vapor extraction
SVOC
semivolatile organic compound
SWRCB
State Water Resources Control Board
TBC
to be considered criteria
TCDD
2,3,7,8 -tetrachl orodib enzodi oxin
TCE
trichl oroethene
TDS
total dissolved solids
TPH
total petroleum hydrocarbons
TPH-D
total petroleum hydrocarbons as diesel
TPH-G
total petroleum hydrocarbons as gasoline
TPH-Mo
total petroleum hydrocarbons as motor oil
TSCA
Toxic Substances Control Act
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USC United States Code
USFWS U.S. Fish and Wildlife Service
UST underground storage tank
VOC volatile organic compound
Westborough Plan Westborough at Easton Specific Plan
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i -i i i i rrr ime i >i '! i ฆ
Aerojet Rocketdyne, Inc., (Aerojet)1 Superfund Site (Site), Sacramento County, California,
Comprehensive Environmental Response, Compensation, and Liability Information System
(CERCLIS) Identification Number CAD9803S8832.
The Site consists of approximately 5,900 acres, along with the footprint of the contaminated
groundwater that extends beyond the Aerojet Property, and is located about 15 miles east of
Sacramento, California. The Aerojet Superfund Site is divided into nine operable units (OUs)
because of the overall size of the remediation effort and to expedite the remediation. The scope
and definition of the current Aerojet OUs were pursuant to a 2002 modification of the 1989
Partial Consent Decree (PCD) for the Site. This Record of Decision (ROD) addresses OU-6
(Boundary OU).
The OU-6 ROD addresses 81 areas that have been identified as areas requiring an action
(referred to as remedial action areas). The 81 remedial action areas are shown on
Figures 2-23 to 2-31 and include:
AE-R-1
AE-SV-R-6
AW-R-12
L2-R-9
BC-R-1
CP2-R-10
AE-R-2
AE-SV-R-7
AW-R-13
L2-R-10
BC-R-2
CP2-R-11
AE-R-3
AE-SV-R-8
AW-R-14
L2-R-11
WL-R-1
CP2-R-12
AE-R-4
AW-R-1
AW-R-15
L2-SV-R-1
MA-R-1
CP2-SV-R-1
AE-R-5
AW-R-2
AW-R-16
L2-SV-R-2
MA-SV-R-1
CP2-SV-R-2
AE-R-6
AW-R-3
AW-SV-R-1
L2-SV-R-3
CP2-R-1
CP2-SV-R-3
AE-R-7
AW-R-4
L2-R-1
L5-R-1
CP2-R-2
CP2-SV-R-4
AE-R-8
AW-R-5
L2-R-2
L5-R-2
CP2-R-3
CP2-SV-R-5
AE-R-9
AW-R-6
L2-R-3
L5-R-3
CP2-R-4
CP2-SV-R-6
AE-SV-R-1
AW-R-7
L2-R-4
L5-R-4
CP2-R-5
DPEB-R-1
AE-SV-R-2
AW-R-8
L2-R-5
L5-R-5
CP2-R-6
DPEB-SV-R-1
AE-SV-R-3
AW-R-9
L2-R-6
L5-SV-R-1
CP2-R-7
AE-SV-R-4
AW-R-10
L2-R-7
L5-SV-R-2
CP2-R-8
AE-SV-R-5
AW-R-11
L2-R-8
L5-SV-R-3
CP2-R-9
1 - Aerojet General Corporation acquired Rocketdyne, Inc. in 2013, and is now operating as Aerojet Rocketdyne, Inc.
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The Remedial Investigation/Feasibility Study (RI/FS) for OU-6 evaluated all identified potential
source sites and many were deemed to not pose a risk or require a remedial action. Those were
designated as "not retained" areas. Further information for these not retained areas is provided in
Section 2.8 and Table 2-11 of this ROD and in the FS (Shaw, 2012).
1.2 Statement of Basis and Purpose
This decision document presents the U.S. Environmental Protection Agency's (EPA's) selected
soil and soil vapor cleanup remedies for OU-6 at the Aerojet Superfund Site, which were chosen
in accordance with the Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA), 42 United States Code (USC) งง 9601 etseq., as amended, and to the extent
practicable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP),
40 Code of Federal Regulations (CFR) Part 300. This decision is based on EPA's Administrative
Record file. The Proposed Plan (PP) (EPA, 2013) and ROD address the community involvement
requirements of CERCLA.
The State of California Environmental Protection Agency (Cal-EPA), represented by the
Department of Toxic Substances Control (DTSC) and the Central Valley Regional Water Quality
Control Board (RWQCB) (collectively, the "State"), has been the supporting agency during the
RI and FS process for the Aerojet Site. In accordance with 40 CFR 300.430, the State of
California has been involved in the review of this document, actively participated in the
decision-making process, and has provided EPA with invaluable input. The State of California
generally agrees with the cleanup approach for this ROD2 and concurred with the selected
remedies in a letter from DTSC to EPA, dated June 2, 2015.
This ROD addresses volatile organic compounds (VOCs) in soil vapor within OU-6 that may
present a threat to human or ecological health or groundwater quality, and non-VOCs in soil that
may present a threat to human or ecological health or that may present a threat to surface water
or groundwater quality. VOCs include many chlorinated solvents and petroleum-related
compounds, including trichloroethene (TCE), tetrachloroethene (PCE), and benzene among
others. Non-VOCs include semivolatile organic compounds (SVOCs), metals, perchlorate,
and petroleum hydrocarbons. SVOCs include polycyclic aromatic hydrocarbons (PAHs),
polychlorinated biphenyls (PCBs), dioxins/furans, and pesticides. Petroleum hydrocarbons
include three primary classes of compounds: total petroleum hydrocarbons (TPH) as diesel
(TPH-D), as gasoline (TPH-G), and as motor oil (TPH-Mo). Petroleum product contamination is
exempt from CERCLA; however, EPA guidance states that if petroleum product contamination
is commingled with CERCLA hazardous substances, the petroleum contamination is also
addressable under CERCLA. Because the TPH contamination in OU-6 soils is commingled with
other CERCLA hazardous substances, the TPH contamination is addressed in this ROD.
This ROD addresses soil and soil vapor contaminated areas. Although this ROD is not intended
to address groundwater contamination, groundwater contamination is present beneath the OU-6
area. Because there is currently no sitewide land use covenant for groundwater, this ROD will
implement the same institutional controls (ICs) as those adopted by OU-3 and OU-5 RODs, as
2 - See Section 2.11 State Acceptance and Table 2-13 for details concerning differences in approach to the remedy between EPA
and the State.
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well as ICs placed on the Carveout Lands to restrict access and use of groundwater. As stated in
the OU-5 Interim ROD for Groundwater, "These [institutional] controls will include Sacramento
County review of new well drilling permits and prohibitions on access to groundwater on the
land overlaying the contaminated groundwater to restrict use of untreated groundwater within the
contaminated portions of the aquifer until the final water quality objectives have been attained."
(see Appendix A for the Aerojet sitewide groundwater plume locations). In addition, the OU-3,
OU-5, and OU-6 RODs will require ICs enforceable through State land use controls (LUCs)
whenever Aerojet-owned property above a groundwater contaminant plume is transferred. These
restrictions will be implemented through a recorded covenant pursuant to California Civil Code
Section 1471 and other applicable California law, whereby Aerojet covenants to impose these
restrictions. These land use covenants will be binding to Aerojet's successors and assigns as
covenants running with the land. The State of California and EPA (as a third-party beneficiary)
will have the right to enforce these restrictions. Any lease or sale of Aerojet property overlying
the contaminated groundwater in OU-6 shall be subject to the following restrictions:
No recharge of groundwater unless and until expressly permitted in writing by EPA and
the RWQCB
No injection into the groundwater unless approved in writing by EPA and the RWQCB
No sustained extraction of groundwater encountered during excavation for construction
without written approval by EPA and the RWQCB
No drilling or use of wells for the purpose of extracting water for any use, including
domestic, municipal, potable, irrigation or industrial uses; this restriction does not apply
to wells used for site remediation, as approved by EPA and the RWQCB
Aerojet shall give written notice of the groundwater contamination to each buyer, lessee,
renter, and mortgagee of any of these lands; and every lease, deed, mortgage, or instrument
conveying any part of these lands shall expressly provide that it is subject to this Declaration of
Covenants and Environmental Restrictions.
The contaminated groundwater beneath the Aerojet Superfund Site (see Appendix A), including
groundwater beneath OU-6, is being addressed as part of the ongoing interim and final remedial
actions to provide hydraulic containment and remediation of the contamination associated with
releases from Aerojet. As described in the proposed plan, groundwater remediation is being
conducted on an Aerojet sitewide basis. These final and interim remedies for the groundwater
are managed under the OU-3 ROD (EPA, 2001) and OU-5 Interim ROD for Groundwater
(EPA, 2011). The Sitewide ROD (OU-1) will integrate the final remedies for all groundwater,
soil and source OUs, and it will document the aquifer restoration goals for the entire site. The
Remedial Action Objectives established in final and interim remedies will be reviewed for
protectiveness and compliance with applicable or relevant and appropriate requirements
(ARARs). A ROD amendment or explanation of significant differences (ESD) can be used
for necessary revisions. Five Year Reviews will evaluate the remedies to determine if they are
still protective and may recommend modification of the cleanup goals prior to the Sitewide ROD.
In addition to the groundwater ICs already in place, other restrictions already applied to the
OU-6 area include the Sacramento Consultation Zone policy, the environmental covenant for the
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Carve-Out lands, the PCD identifying areas subject to excavation restrictions, and Aerojet's Soil
Excavation or Grading, or Construction Debris Movement Notification Requirements.
1.3 Assessment of Site
As a result of past industrial activities within OU-6, releases of hazardous substances have
contaminated surface soils, the vadose zone, and groundwater. The response actions selected in
this ROD are necessary to protect the public health or the environment from actual or threatened
releases of hazardous substances into the environment.
Description of Selected Remedies
The selected remedies and their major components are summarized in this section. The selected
remedies provide the best approach for cost-effective risk reduction. They will provide
protection to human health and the environment by either removing contaminants from the site,
thereby reducing any residual risk, or by limiting exposure to human receptors and/or ecological
receptors by implementing the selected remedies discussed below. Aerojet retains responsibility
for the operation and maintenance (O&M) of all the selected remedies, including, but not limited
to, permanently covered areas (caps), wells, and ICs.
The selected remedies for OU-6 are as follows:
Alternative 2 - Institutional Controls (ICs)
Alternative 3 - Containment and Engineering Controls, incorporating Alternative 2 ICs
Alternative 4 - Source Removal/Reduction
The following sections describe how these selected remedies are applicable for the contaminated
soil, sediment, and soil vapor within OU-6.
1.4.1 Alternative 2 - Institutional Controls
EPA has selected Alternative 2 (ICs) for all soil areas where the risk to human health is the result
of vapor intrusion and to prevent unacceptable exposures to contamination remaining onsite. ICs
will be implemented to restrict unacceptable land uses, require environmental evaluations, and
establish protection of engineered controls. EPA considers ICs to include "non-engineered
instruments, such as administrative and legal controls, that help to minimize the potential for
human exposure to contamination and/or protect the integrity of a response action". ICs typically
are designed to work by limiting land or resource use, or by providing information that helps
modify or guide human behavior at a site. Some common examples of ICs include zoning
restrictions, building or excavation permits, well drilling prohibitions, easements, and covenants.
Alternative 2 (ICs) was selected for the following three areas. These areas are shown on
Figures 2-28 to 2-31, and are included in Appendix B.
MA-SV-R-1 CP2-SV-R-6 DPEB-SV-R-1
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1.4.2 Alternative 3 - Containment and Engineering Controls, incorporating
Alternative 2 ICs
EPA has selected Alternative 3 (Containment and Engineering Controls, incorporating
Alternative 2 ICs) to address the soil and sediment contamination requiring action in OU-6.
Alternative 3 (Containment and Engineering Controls, incorporating Alternative 2 ICs) consists
of the following:
Placement of capping materials (pavement, gravel layer, etc.) over areas with chemicals
posing potential risks above commercial/industrial use levels;
Monitoring the presence, thickness, and maintenance of new and existing capping
materials (e.g., buildings, foundations, roadways, and parking lots) that currently overlie
areas of contaminants of concern (COCs) within OU-6 to ensure the integrity of the
capping materials;
Modification and monitoring of the heating, ventilation, and air conditioning (HVAC)
systems of existing buildings to ensure that there are sufficient air exchange rates to limit
vapor intrusion and reduce indoor air concentrations to safe levels based on the Johnson
and Ettinger Model (1991) or an alternative industry-accepted standard calculation;
Construction and operation of foundation venting systems around and/or beneath existing
buildings, and adoption of engineering or management controls requiring vapor
mitigation to reduce or prevent VOC intrusion into buildings through vapor barriers
(synthetic membrane) and subslab venting (SSV) systems and/or subslab depressurization
(SSD) systems or alternative system designed to prevent intrusion of contaminants to
indoor air; and
Construction and operation of foundation venting systems around and/or beneath new
construction and adoption of engineering or management controls requiring vapor
mitigation to reduce or prevent VOC intrusion into buildings through the installation of
vapor barriers (synthetic membrane) such as SSD, SSV or alternative system designed to
prevent intrusion of contaminants to indoor air.
Alternative 2 ICs, as described in Section 2.10.2, are incorporated as part of Alternative 3 and
would be implemented as part of this alternative to protect the integrity of the cap and vapor
intrusion mitigation systems, to identify the presence of engineering controls in place, and for
long-term protection and maintenance requirements. These long-term requirements refer to the
activities necessary to ensure that engineering controls are maintained and that ICs continue to be
enforced. If additional characterization demonstrates that there is no remaining risk from soil
contaminants in the vadose zone to any receptors above acceptable levels, then ICs under
Section 2.10.3 would continue to apply only where groundwater contaminants continue to pose
a risk.
Alternative 3 (Containment and Engineering Controls, incorporating Alternative 2 ICs) was
selected for the following 11 areas. These areas are shown on Figures 2-23 through 2-31, and
included in Appendix B.
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AE-R-1
AE-R-2
AE-R-3
AE-R-4
AE-R-5
AE-R-6
AE-SV-R-3
AW-SV-R-1
L2-SV-R-1
L5-SV-R-3
DPEB-R-1
1.4.3 Alternative 4 - Source Removal/Redtictloit
EPA has selected Alternative 4 (Source Removal/Reduction) for most areas in OU-6.
Alternative 4 consists of two main components: (1) excavation and offsite disposal of soil
containing site-related chemicals at concentrations greater than acceptable levels for future use;
and (2) soil vapor exaction (SVE) to remove as much contaminated soil vapor associated with
the source area as possible. ICs may be implemented in areas where contamination remains in
place at concentrations greater than acceptable levels for unrestricted use, such as areas
inaccessible for excavation (i.e., beneath building foundations or around utilities). ICs will also
mitigate unacceptable exposures and protect the SVE system. The areas selected for
Alternative 4 are shown on Figures 2-23 to 2-31, and included in Appendix B.
Alternative 4 (Source Removal/Reduction) (Excavation or Excavation with Soil Flushing and
Air Stripping) was selected for the following 51 areas in OU-6:
AE-R-7
AE-R-8
AE-R-9
AW-R-1
AW-R-2
AW-R-3
AW-R-4
AW-R-5
AW-R-6
AW-R-7
AW-R-8
AW-R-9
AW-R-10
AW-R-11
AW-R-12
AW-R-13
AW-R-14
AW-R-15
AW-R-16
L2-R-1
L2-R-2
L2-R-3
L2-R-4
L2-R-5
L2-R-6
L2-R-7
L2-R-8
L2-R-9
L2-R-10
L2-R-11
L5-R-1
L5-R-2
L5-R-3
L5-R-4
L5-R-5
BC-R-1
BC-R-2
WL-R-1
MA-R-1
CP2-R-1
CP2-R-2
CP2-R-3
CP2-R-4
CP2-R-5
CP2-R-6
CP2-R-7
CP2-R-8
CP2-R-9
CP2-R-10
CP2-R-11
CP2-R-12
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Alternative 4 (Source Removal/Reduction) (SVE) was selected for the following 16 areas in
OU-6:
AE-SV-R-1
AE-SV-R-2
AE-SV-R-4
AE-SV-R-5
AE-SV-R-6
AE-SV-R-7
AE-SV-R-8
L2-SV-R-2
L2-SV-R-3
L5-SV-R-1
L5-SV-R-2
CP2-SV-R-1
CP2-SV-R-2
CP2-SV-R-3
CP2-SV-R-4
CP2-SV-R-5
1.5 Statutory Determinations
The selected remedies are protective of human health and the environment, comply with federal
and state requirements that are applicable or relevant and appropriate to the remedial action, are
cost-effective, and use permanent solutions to the maximum extent practicable. The selected
remedies comply with the offsite disposal requirements of CERCLA and the NCP.
These remedies also satisfy the statutory preference for treatment as a principal element of the
remedy (i.e., reduces the toxicity, mobility, or volume of hazardous substances, pollutants, or
contaminants as a principal element through treatment) for the contaminated soil and soil vapor.
The selected remedies will result in hazardous substances, pollutants, or contaminants remaining
onsite above levels that would allow for unlimited use and unrestricted exposure. Therefore, a
statutory review (i.e., a CERCLA 5-year review) will be conducted within 5 years after initiation
of remedial action, and every 5 years thereafter, to ensure that the remedy is, or will be,
protective of human health and the environment.
1.6 ion Checklist
The following information is included in Part 2: The Decision Summary of this ROD (additional
information can be found in the Administrative Record file and Administrative Record Index
[Appendix C] for OU-6):
COCs and their respective health-based concentrations - Table 2-1 and Appendix B;
Summary of Site Risks - Section 2.7 (page 71);
Performance Standards (cleanup or containment levels) established for the COCs and the
basis for these levels - Tables 2-2 and 2-3;
How source materials constituting principal threats are addressed - Section 2.12
(page 134);
Current and reasonable anticipated future land use assumptions - Section 2.6.1 (page 61),
and Figures 2-19 to 2-22;
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Estimated capital, O&M, and total present value costs, discount rate, and the number of
years over which the remedy cost estimates are projected - Section 2.11 (page 127),
Table 2-12, and Appendix D; and
Key factors that led to selecting the remedy - Section 2.13 (page 143).
This ROD was prepared consistent with guidance published by EPA for preparation of RODs
(EPA, 1999).
1.7 Authorizing Signature
7/ฃ^/5~~
y JAffLyonyy7^ Date
Acting Assis^mt Directof; Superfund Division
California Site Cleanup Branch
U.S. Environmental Protection Agency Region IX
8
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PART 2: THE DECISION SUMMARY
2.1 Site Name, Location, and Description
The Aerojet Superfund Site is located within Sacramento County, approximately 15 miles east
of Sacramento, California (see Figure 2-1). It is bounded on the west and north by the cities
of Rancho Cordova and Folsom along with the communities of Carmichael, Fair Oaks, and
Gold River - with a combined population of approximately 237,000 residents. Unincorporated
Sacramento County lies to the south and east of Aerojet.
OU-6 is generally located along the western and northern boundaries of the Aerojet Superfund
Site, and total acreage for OU-6 is 701 acres.
Because of the complex history of past operations and size of OU-6, it was sub-divided into
nine Management Areas (MAs) and seven Open Space (OS) areas to focus the remedial
investigations on sources with the potential for releases to the environment. A brief description
of each of the source areas within OU-6 are shown in Table 2-11. As discussed in greater detail
later in Section 2.8, contaminated areas within each of the MAs that require remediation
(Remedial Action areas) have been identified and a preferred remedy has been selected.
The nine M As and seven OS areas are described below and are also shown on Figure 2-2.
9
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Administration Area: The Administration Area is the historical liquid rocket manufacturing
area, and historical and current administration area at the Aerojet propulsion facility.
Potential source areas within the Administration Area are associated with liquid rocket
manufacturing and the drainage system extending from the manufacturing buildings within
the Administration Area to the West Lakes Area. Locations where piping discharged to
ditches were identified as potential source areas. The primary chemicals associated with
liquid rocket manufacturing were chlorinated solvents and metals. The following subareas
have been defined for the Administration Area:
- Administration Area East: Source Areas 3D, 4D, 1 ID, 50D, and 5 ID; Building 20034,
Resource Conservation and Recovery Act (RCRA) Units B (Bldg. 20037),
C (Bldg. 20029), and X (Bldg. 20873) (all closed under RCRA) (see Figure 2-3), and
associated septic tanks, PCB transformers, and underground storage tanks;
- Administration Area West: Source Areas 5D, 6D, 9D, 12D, 50D, 52D FWOT, 52TB,
D(b), and D(c); RCRA Units W and Y (closed under RCRA) (see Figure 2-4) and
associated septic tanks, PCB transformers; and
- Former Sewage Treatment Plant: Source Areas 8D and D(d) (see Figure 2-4).
Line 2 Region: The Line 2 Region (Source Areas 28E, 29E, 59E, E[d], E[e], E[m], E[n];
Drum Storage Area (DSA); associated septic systems; and RCRA Units T and Z) includes
various features such as collection systems, floor drains, sumps, storage areas, and a cleaning
slab associated with the drum-cleaning activities in the DSA; drainage ditches; tanks; and
septic tanks and leach fields (see Figure 2-5).
Line 5 North: The Line 5 North Area encompasses three source areas (Source Areas 5 IE,
52E, and E[l]) and various other features including sumps, a possible missile test stand,
test cells and associated blast areas, a material storage area, and drains associated with
former activities conducted at Building 05087 (see Figure 2-6). Building 05087 is identified
as a former engineering test laboratory where solid propellants, liner materials,
1,1,1-trichloroethane (1,1,1-TCA), and TCE were handled.
West Lakes Area/OS-6: The West Lakes Area receives stormwater runoff from various
areas of the Aerojet facility via the Main Administration Area Ditch and Buffalo Creek.
No source areas have been identified within the West Lakes Area. However, the OU-6 Field
Sampling Plan (FSP) identified the West Lakes Area as a feature to investigate because the
potential exists for chemicals from various parts of the Aerojet Superfund Site to have been
carried into and deposited within the West Lakes Area via surface water and sediment
transport through the Main Administration Area Ditch and Buffalo Creek (see Figure 2-7).
Because of this, the West Lakes Area was included in the OU-6 RI Report.
Buffalo Creek: Although Buffalo Creek was not identified as a source area, the OU-6 FSP
identified it as an investigation area because of the potential for stormwater from many
source areas in Area 00, Line 1, Line 2, Line 6, and Zone 3 to discharge into Buffalo Creek
(see Figure 2-8). Within OU-6, Buffalo Creek comprises three principal drainages referred to
in this report as "Upper," "Lower," and "Cutoff." Upper Buffalo Creek includes its current
10
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channel beginning just east of the OU-6 to the point of discharge into West Lakes Area.
Lower Buffalo Creek includes the current channel that receives surface water discharges
from the West Lakes Area and from the American River Groundwater Extraction and
Treatment (ARGET) facility. Buffalo Creek Cutoff refers to a section of drainage adjacent to
Line 2 that formerly connected Buffalo Creek and the Main Administration Area Ditch. This
section of the channel was abandoned following construction of the portion of Buffalo Creek
that runs adjacent to Line 2.
Chemical Plant 2 Area: Chemical Plant 2 was originally operated as a nitroplasticizer
manufacturing facility by Aerojet. The plant was shut down in 1968 and later reactivated in
1975 by Cordova Chemical Company for other chemical manufacturing activities. Chemical
Plant 2 encompasses Source Areas 59F, 60F, 6IF, 62F, CP2-07, CP2-08, and F(c); associated
septic systems; and RCRA Units E and I (see Figure 2-9). Additionally, two deep injection
wells associated with historical waste operations are present within the Chemical Plant 2
Area; however, these injection wells are under a post closure permit administered by the
DTSC under the corrective action program (RCRA) and, therefore, were not included in this
evaluation. Various features at Chemical Plant 2 include former offices, control rooms,
laboratories (Building 15001) associated with the chemical plant, chemical manufacturing
facilities, collection systems, waste lines, floor drains, sumps, former hazardous waste and
material storage areas, holding basins, aboveground storage tanks (ASTs), underground
storage tanks (USTs), septic tanks and leachfields, drainage ditches, and low-lying areas.
Chemicals used or manufactured at Chemical Plant 2 included chemicals used in the
nitroplasticizer process, solvents, diesel, pesticides, and oil containing PCBs.
Magazine Area (Area 48)/OS-3: The Magazine Area/OS-3 consists of storage bunkers,
shipping and transfer facilities, a low area, and safety shelters (see Figure 2-10). In the
Magazine Area/OS-3, two septic systems and a former RCRA Unit (RCRA-C) were
identified as features to investigate in the OU-6 FSP.
Dredge Pit and Eastern Basin: Two historical dredge pits are located approximately
2,400 feet (0.5 mile) northeast of Chemical Plant 2. The westernmost dredge pit
(Source Area 25F) is referred to as the Dredge Pit, and the easternmost pit is referred to as
the Eastern Basin (see Figure 2-11). Although the Eastern Basin was not identified as a
source area, the OU-6 FSP identified it as an investigation area.
OS Areas 1, 2, 4, 5, and 7 (OS-1, OS-2, OS-4, OS-5, and OS-7): Large areas of contiguous
land (buffer land between the MAs) within OU-6, not encompassed by Aerojet-defined MAs
or source areas, were identified as OS Areas to manage the CERCLA process for these lands.
During the development of the OU-6 FSP, Aerojet conducted site walks, reviewed current
and historical aerial photographs, interviewed employees, and researched documents in an
attempt to identify any features within these OS Areas that had a potential for chemicals to be
released to the environment (see Figures 2-2, 2-9, 2-10, and 2-12). In addition, these areas
were investigated to evaluate the risk from chemicals present in groundwater beneath the
OS Area land from upgradient sources.
- OS-1 consists of buffer lands between Chemical Plant 2 and areas west of the Aerojet
Superfund Site. No source areas have been identified within OS-1, but a railroad line
11
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transects the southern portion of OS-1 from east to west. Reconnaissance of this section
of rail line as part of the Carve-Out work performed in 1999 and 2000 identified no
potential areas of environmental concern (Environmental Resources Management [ERM],
2000 and 2001). However, during the development of the FSPs, a reported plasticizer spill
in the railroad ballast west of the Chemical Plant 2 fence line and a pond receiving
discharge from the Spill Prevention, Control, and Countermeasures (SPCC) sump and
Chemical Plant 2 Source Area 59F (Figure 2-9) were identified as features to investigate.
RI samples were collected to evaluate these features.
- OS-2 consists of buffer lands between Chemical Plant 2, the Magazine Area, and Line 3.
No source areas have been identified within OS-2, and no indications of historical
industrial activities were observed during site reconnaissance performed as part of the
OU-6 RI. However, during the development of the FSP, a debris pile, drums, and a pond
located east of the Chemical Plant 2 fence were identified as features to investigate.
RI samples were collected to investigate these features.
- OS-4 consists of buffer lands between the Magazine Area and Chemical Plant 1.
No source areas have been identified within OS-4, and no indications of historical
industrial activities were observed during site reconnaissance performed as part of the
OU-6 RI. No RI samples were collected at OS-4.
- OS-5 consists of buffer lands between Line 2 and Line 5 North. No source areas have
been identified within OS-5, but a storage yard and two former tanks are present in the
southeast corner of the site near the dirt road west of Buffalo Creek. RI samples were
collected to evaluate these features.
- OS-7 consists of buffer lands west of Line 5 North. No source areas have been identified
within OS-7, and no indications of historical industrial activities were observed during
site reconnaissance performed as part of the OU-6 RI. No RI samples were collected at
OS-7.
Area 39: Aerojet Area 39 encompasses approximately 90 acres within the 835-acre
Prairie City State Vehicular Recreation Area (located approximately 1 mile southeast of
Aerojet) that is owned and operated by the State of California. Rocket test facilities were
constructed within Area 39 by Aerojet in the 1960s, but the programs were halted and the
facilities were never used. Area 39 was used between 1970 and 1972 for burning chemical
wastes generated by Aerojet. Area 39 was not evaluated for remedial action because the
Screening-Level Ecological Risk Assessment (SLERA) recommended a Baseline Ecological
Risk Assessment for the area. Based on this recommendation, the Agencies agreed that the
Area 39 Baseline Ecological Risk Assessment and resulting FS would be deferred to the
Island Operable Unit (OU-7) and is not discussed further in this ROD.
12
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USBZJ
U.S. EPA REGION IX
** pi'^'
AEROJET GENERAL CORP.
SUPERFUND SITE
FIGURE 2-2
Location of Management and Open Space Areas,
Boundary Operable Unit
Operable Unit 6 Record of Decision
ES042114142800SAC
-------
itengls ani
iquipment
Former Vehicle
Maintenance
Shop
RCRAX
:id Holding
Former Septii
\ Tank
Former Fuel
Oil UST v
Former
Company
Store
Approximate,
Formel: Lopatlon
Wastet)il TapJซ
f^^Fbrmer TCE
Degreaser
Former
Radiographic
Facility
Compressor 7y
Blowdown llll
wea llll
Chemical Lab
\ Sump^^
Freon
Sump,
3D HydroV
l0oฐA Sumto"^
Former KerosBn
Former Oil/
Water Sump
Former Etching & Plating Area
i Former Electron Beam
- welding Sump
Former Autoclave
Vapor Separation
Waste Sump
Former Tanl
Former Blow
Former
Solvent
,Storage
Area
20006
A20-ST0\02
lachine Shop Waste Sump
Floor Drain
20008
Former Paint
Booth DraicK
Lindberg
Sump
orrpeTPCB
fansformer
20015
former Solvent
Storage Area
Storm Drain
(aste Storage Tanks
\ & Degreasers
\ Formervfllm^
Former Chemical
Storage Area
EXPLANATION
50D Potential Source Area
Boundary Operable Unit (BOU)
Consent Decree Boundary
Drainage Culvert
Fence
Underground Culvert
Road
-|||||- Railroad
Building
Former Structure
Above Ground Storage Tank
Surface Drainage
A20-ST14 Septic Tank and Leach Line
II
Surface Water Flow Direction.
1^
N
I
Scale: 1" =
i i "
$ A \
pro-!^
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
FIGURE 2-3
Site Features Map, Administration Area East
Operable Unit 6 Record of Decision
ES042114142800SAC
-------
20006
Septic Leach
Pits
20008
Administration
Area West
52DFWOT
\ r Inactive
/ Plating
\ Area
w\ \
Hazardous \
Materials Storage \Wv-
Paint
Spray
Booth
20091
20015
20009
Former Waste
Oil Tank
Waste Treatment
Clean
Room
SMUD
Electrical
Substation
Bermed V
Pond N
Hazardous
Materials
Storage
Concrete
Pad
Aerator
Digester
20018
RCRAW
Treatment
Works
Treatment
Works
20012
Digester-/
RCRAY
EXPLANATION
52D Potential Source Area
Boundary Operable Unit (BOU)
Consent Decree Boundary
Drainage Culvert
Fence
Underground Culvert
Road
Railroad
Building
Former Structure
I I
Above Ground Storage Tank
Surface Drainage
\\ //
ST26 ^ Septic Tank and Leach Line
II
Surface Water Flow Direction.
N
N
I
Scale: 1" = 200'
i i i
0 100 200
s Ol \
iw/
St Poltc
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
FIGURE 2-4
Site Features Map, Administration Area West
Operable Unit 6 Record of Decision
ES042114142800SAC
-------
ES042114142800SAC
-------
Buffalo Creek
Tower Pad
Drainage Ditch
05087
Concrete Wash Sump
05097
Material
Storage Area
EXPLANATION
51 E Potential Source Area
Boundary Operable Unit (BOU)
Management Area Boundary
Road
Pavement
20009
ST26
Building
Former Structure
Above Ground Storage Tank
Surface Drainage
Septic Tank and Leach Line
N
I
Scale: 1"= 100'
\Mu
phoi4
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
FIGURE 2-6
Site Features Map, Line 5 North
Operable Unit 6 Record of Decision
ES042114142800SAC
-------
Main Administration Ditch
AR GET
Discharge Point
(Pump Station
Buffalo Creek-
Outlet Gate
Eastern Pond
. Diversion
Gate
Outlet Gate
Western Pond
Outlet Gate
Bypass Gate
Diversion Gate
Buffalo Creek
Buffalo Creek
Diversion Gate
ARGET Facility
GET E/F
Discharge Point
EXPLANATION
Potential Source Area
Boundary Operable Unit (BOU)
Consent Decree Boundary
Drainage Culvert
Road
20009
Building
Above Ground
Storage Tank
Surface Drainage
Septic Tank and Leach Line
AR American River
GET Groundwater Extraction and Treatment
N
I
Scale: 1"= 500'
i i i
0 250 500
^t0SX
$ o \
ysuj
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
FIGURE 2-7
Site Features Map, Westlakes and Open Space Area 6
Operable Unit 6 Record of Decision
ES042114142800SAC
-------
Buffalo Creek
Cutoff
Former Sewage
Treatment Plant
'' ARGET
/ Discharge Point
lx\ Westlakes ^
OS-6
North
ARGET Facility^
I GET E/F
Discharge Point
EXPLANATION
Buffalo n , lc
Creek Pฐtentla' Source Area
Boundary Operable Unit (BOU)
Consent Decree Boundary
Drainage Culvert
Underground Culvert
Fence
Road
H||||- Railroad
L2-ST24 [
AR American River
GET Groundwater Extraction and Treatment
Building
Former Structure
Above Ground Storage Tank
Surface Drainage
Septic Tank and Leach Line
r*
N
Scale: 1" = 1000'
i i i
0 500 1000
^t0SX
i \
WJ
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
FIGURE 2-8
Site Features Map, Buffalo Creek
Operable Unit 6 Record of Decision
ES042114142800SAC
-------
Material
Storage Area
Holding Basin
Trench
RCRA-I
Former Aboveground
Storage & Process
Tanks
:ormer Tanks
Aboveground
Tanks
owers
/, Concrete Sumps
litrogen
Tank
at on of
* I
imical Plant
Former
Hazardous
Storage Map
Former Loc
Stoufer Ch
Injection Well #2
Aboveground Tank \ Js
(no. 2 diesel) I. ^
15010
Former Nitroethane AST
Former Tank
Locations
Former Test Incinerator
15004
Paraldehyde
\ Tank\
.Former
Tanks
\ \
RCRA-E \NV\ CP2ST01-3
\V 4,1
15017
15001
EXPLANATION
62F Potential Source Area
Boundary Operable Unit (BOU)
Consent Decree Boundary
Drainage Culvert
Underground Culvert
Road
Management Area Boundary
HIHh Railroad
Building
L2-ST24
Former Structure
Above Ground Storage Tank
Surface Drainage
Septic Tank and Leach Line
Injection Well Location
Surface Water Flow Direction.
A x
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
FIGURE 2-9
Site Features Map, Chemical Plant 2
Operable Unit 6 Record of Decision
Scale: 1" = 160'
ES042114142800SAC
-------
ES042114142800SAC
-------
ES042114142800SAC
-------
Buffalo Creek
Cutoff
AR GET
Discharge Point
OPEN SPACE AREA 6
OPEN
SPACE
AREAS
OPEN SPACE
AREA 7
ARGET Facility^
GET E/F
Discharge Point
EXPLANATION
Boundary Operable Unit (BOU)
Consent Decree Boundary
Drainage Culvert
Road
Management Area Boundary
Building
Former Structure
Above Ground Storage Tank
Surface Drainage
American River
Groundwater Extraction and Treatment
U.S. EPA REGION IX
M-. ....
SUPERFUND SITE
I ^^7 I AEROJET GENERAL CORP.
FIGURE 2-12
Site Features Map, Open Space Areas 5, 6, and 7
Operable Unit 6 Record of Decision
Scale: 1" =
ES042114142800SAC
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2,2 Site History and Enforcement Activities
Aerojet Rocketdyne, Inc. (formerly known as Aerojet General Corporation), a subsidiary of
Aeroject Rocketdyne Holdings, Inc. (formerly known as GenCorp, Inc.) (referred to as Aerojet in
this document) began operations in Rancho Cordova, near Sacramento, California after acquiring
approximately 8,500 acres in December 1950. Operations included manufacturing and testing
liquid and solid rocket engines and motors for military and commercial applications, and
formulating and producing a number of chemicals, including rocket propellant agents, agricultural
pesticides, pharmaceuticals, and other industrial chemicals. The State of California issued waste
discharge requirements to Aerojet in May 1952. The Cordova Chemical Company operated
chemical manufacturing facilities on the Aerojet complex from 1974 to 1979. It was announced
on June 14, 2013, that Aerojet completed the acquisition of the Pratt & Whitney Rocketdyne
business (Rocketdyne). Aerojet combined Rocketdyne with Aerojet General Corporation and
currently operates as Aerojet Rocketdyne, Inc. However, for EPA tracking and recording
purposes, this ROD will to refer to Aerojet Rocketdyne, Inc., as Aerojet.
Throughout Aerojet's operational history, some wastes were disposed of on the property in
surface impoundments, landfills, deep injection wells, septic tanks and associated leach fields,
and open burn areas. Although numerous chemicals were used on the Aerojet Superfund Site,
TCE, PCE, perchlorate, and n-nitrosodimethylamine (NDMA) are the most prevalent chemicals
encountered. Historical operations at the Aerojet Superfund Site have resulted in the discharge of
some of these chemicals to the vadose zone and percolation into the underlying groundwater.
Since 1979, Aerojet has investigated the site to determine the nature and extent of the chemicals
present, and to identify and implement mitigation measures to protect public health and the
environment.
The Aerojet Superfund Site was placed on the National Priorities List (NPL) on August 8, 1983.
Portions of the state-led Inactive Rancho Cordova Test Site (IRCTS) are considered part of the
Aerojet NPL site where hazardous substances originally on the Aerojet facility migrated to or
otherwise came to be located on the IRCTS. On June 23, 1989, a PCD was entered by the
U.S. District Court for the Eastern District of California. The PCD obligates Aerojet to complete
an RI/FS for the 8,500-acre main facility, portions of the 3,820-acre IRCTS area, and three other
smaller parcels (Areas 39, 40, and 41) near the main Aerojet facility, where open burning was
conducted. The parties to the PCD are Aerojet General Corporation, DTSC, RWQCB, and EPA.
Aerojet constructed five groundwater extraction and treatment (GET) systems prior to the PCD.
Requirements for the operation, maintenance, and effectiveness evaluation of the GET systems
were incorporated in the PCD.
The PCD established specified procedures and obligations toward achieving the goals delineated
in the CERCLA of 1980 (referred to as Superfund) and the NCP. Exhibit II of the PCD outlines
the OU RI/FS Program Plan. This exhibit contained a plan for completing a facility-wide RI/FS
in three phases: Scoping Phase, Phase I RI/FS, and Phase II RI/FS. Prior to 2002, Aerojet had
completed the Scoping Phase and a majority of the Phase I RI/FS.
35
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Exhibit II of the PCD was modified in 2002 by Stipulation and Order Modifying Partial Consent
Decree3 (EPA, 2002) to allow the completion of the RI/FS through an OU approach and the
exclusion of 2,600 acres from the boundaries of the Aerojet Superfund Site. The 2,600 acres
were removed (carved out) from the Superfund Site following the completion of a thorough
review that indicated that the lands were not used for industrial purposes, and were deemed
appropriate for carve out (hereinafter, "Carve-Out Lands").
Exhibit III of the PCD identified five initial OUs and 317 potential source areas that are described
as "location[s] above the water table where soils or other materials potentially contain hazardous
substances of such character and quantity as to warrant evaluation in a Remedial Investigation
[RI]." Initial investigations identified 14 additional potential source areas for a total of
331 potential source area sites. Thirty-eight of the potential source areas are addressed under the
five initial OUs identified in Exhibit III.
In 2002, EPA issued to Aerojet a Unilateral Administrative Order (UAO) for Remedial Design and
Remedial Action for the Western Groundwater Operable Unit (OU-3). Under the Order, Aerojet
was directed to contain and remediate contaminated groundwater on the western side of the Site.
In 2004, Aerojet prepared a Program Plan Modification Report (Aerojet, 2004) in accordance with
the PCD, which grouped the remaining 293 potential source areas into the following four OUs:
OU-6 (Boundary OU)
OU-7 (Island OU)
OU-8 (Eastern OU)
OU-9 (Central OU)
Figure 2-13 shows the locations of each OU and the groundwater plume extent.
In 2011, EPA issued to Aerojet, a UAO for the Performance of Remedial Design and Final
Remedial Action for Soil within the Perimeter Operable Unit (OU-5) and a UAO for the
Performance of Remedial Design and Interim Remedial Action for Groundwater at OU-5. The
OU-6 Remedial Design and Remedial Action will also be performed by Aerojet.
Aerojet maintains a RCRA post closure permit for the underground deep injection wells in OU-6
and a RCRA permit for two units outside of OU-6. With the exception of injection wells, all
RCRA units in OU-6 have been closed by DTSC. The post closure monitoring of the RCRA
units themselves is conducted by DTSC. Any residual contamination in the environment as a
result of releases from the units is addressed under this ROD. Additionally, septic tanks and
underground storage tanks identified during the Scoping Evaluation are included in the
investigation of the source area in which they are located.
The CERCLIS Identification Number is CAD980358832. The Lead Agency is EPA, supported
by the California RWQCB, Central Valley Region and by DTSC.
3 - Pursuant to the Paragraph 18 of the Stipulation and Order, this document is referred to as the "2001 Stipulation and Order
Modifying Partial Consent Decree" even though the executed Order was not filed with the Court until 2002.
36
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Composite plume
Aerojet Property Line 2008
OU3 Western Groundwater
OU3 partition
OU7
OU4
OU5
OU6
OU8
OU9
carveout
OU5 Zone Areas
Notes:
1 .The chemical data used to prepare the
contours were collected from 2008 to 2011.
2. The contours represent the maximum
extent of the contaminants across the six
aquifer layers based on available data.
^t0SX
Kmj
PfiO^
U.S. EPA REGION IX
AEROJET GENERAL. CORP.
SUPERFUND SITE
FIGURE 2-13
Composite Plume Map, May 2014
Operable Unit 6 Record of Decision
ES042114142800SAC
-------
2.3 Commur n
Community concern about the site began in 1979, when contamination was discovered in
groundwater. Community members reached out to the RWQCB out of concern over VOC
contaminants in the river, and a dialogue over contamination from the site began. Community
interest surrounding the Aerojet Superfund Site grew through the 1980s and again in the
mid-1990s as knowledge of perchlorate contamination became more widespread. Through a
collaborative effort among regulators. Aerojet, local water agencies, and concerned community
members, the EPA Aerojet Community Advisory Group (CAG) was formed in 2001. Since its
formation, the CAG has met regularly with EPA, Aerojet, DTSC, RWQCB and others to discuss
issues related to the site and comment on cleanup plans. Site information and assistance has been
provided to the CAG primarily by the EPA site team, Aerojet, DTSC, and RWQCB since 2001.
In 2013 and leading up to the release of the OU-6 Proposed Plan, the CAG began to focus on
development plans for the Aerojet lands and concern over the potential effects of contamination
on future residents. Furthermore, the CAG expressed specific interest in the following
overarching topics:
Understanding the cleanup process and long-term strategies to maintain site remedies
Understanding contamination as it relates to land development
Enhancing community outreach and education
The RI/FS Report and Proposed Plan for OU-6 were made available to the public in September
2012 and May 8, 2013, respectively. These documents can be found in the Administrative
Record file of the information repositories maintained at EPA Region IX Superfund Records
Center at 95 Hawthorne Street in San Francisco and at the California State University
Sacramento Library Reference Desk, 2000 State University Drive East, Sacramento, California.
The notice of availability of the RI/FS Report and Proposed Plan, and date and location for the
public meeting and public comment period (May 8 through June 7, 2013) was published the
week prior to the start of the public comment period in the Sacramento Bee newspaper and sent
to the Aerojet mailing list. The public meeting was held May 15, 2013. Transcripts of the public
meeting are part of the Administrative Record file at the repositories, and EPA's response to
comments received at the public meeting and written comments are part of this ROD (see
Appendix E).
An overview of the Proposed Plan was presented by EPA at the public meeting, and questions
were taken prior to acceptance of formal public comments. The Aerojet CAG has been active in
discussions with EPA throughout the development of the OU-6 RI/FS Report and Proposed Plan.
The CAG also requested additional time to submit comments on the Proposed Plan due to the
complexity of the document. The public comment period was extended out an additional 120 days,
making the entire public review period May 8 through September 20, 2013.
EPA spent considerable effort interviewing and meeting with land use planning officials from
Sacramento County, Rancho Cordova, and Folsom. A great deal of planning has already been
approved by local jurisdictions for the development of the Aerojet property near and including
parts of OU-6. EPA prepared a report on the land use plans based on the March 2010
39
-------
information. The draft report was presented to the local officials and to the community for
review. This information was also presented during the CAG meeting in December 2012.
The information, still current, is summarized in Section 2.6.
2,4 Scope and Role of the Operable Unit or Response Action
The Aerojet Superfund Site is a large facility with groundwater contamination that has migrated
off Aerojet property. EPA and the State of California have negotiated with Aerojet to organize
the site into OUs through a modification to the PCD, as follows:
OU-1: OU-1 is reserved for the sitewide final ROD integrating remedial actions for all of
the OUs.
OU-2: OU-2 has been merged into OU-5. OU-2 was initiated in 1995 pursuant to a
Unilateral Administrative Order for control of off-property VOC-contaminated groundwater
on the north side of the Aerojet Superfund Site. OU-2 is also referred to as the American
River OU. The UAO was withdrawn, and work for this part of the site was accomplished
under RWQCB Order 96-230 and Order 500-718 (for perchlorate treatment in Zone 1).
In July 1998, the ARGET became operational as an interim groundwater action to contain
VOCs not captured on the north side of the Aerojet Superfund Site by the formerly active
GET D.
OU-3: Western Groundwater OU (OU-3) contains and remediates groundwater contamination
on the western side of the Aerojet Superfund Site, including groundwater beneath OU-6.
A number of water supply wells have been lost to groundwater contamination, and it had been
projected that approximately 20 public water supply wells could be lost over the next 25 years
without a successful OU-3 remedial action. Although all adversely impacted public water
supplies around the Aerojet Superfund Site have been replaced with uncontaminated water,
ingestion of untreated groundwater extracted from the aquifer would pose a current and
potential risk to human health that exceeds EPA's acceptable risk range. The Western
Groundwater OU (OU-3) has a groundwater ROD that was finalized in 2001. The remedy
includes ICs prohibiting use of contaminated groundwater on Aerojet property overlying the
plume within OU3. Construction of remedial actions selected in the 2001 ROD for OU-3 is
nearly complete.
OU-4: OU-4 will address remediation of soil and groundwater in Area 41 caused by
Aerojet's burning of industrial wastes on 500 acres of property leased from others. Area 41
has VOC and perchlorate contamination in groundwater; as well as metals, and perchlorate
contamination in soil.
OU-5: Perimeter Groundwater OU (OU-5) will contain and remediate groundwater around
the remaining three sides of Aerojet (north, east, and south) not addressed by OU-3. OU-5
includes Aerojet's GETs A, B, D; the ARGET; and groundwater for Area 39. EPA and the
State of California have a long history of collaboration in addressing the Aerojet Superfund
Site, and this cooperation is particularly evident in groundwater contamination portions of
OU-5. The work performed under interim RWQCB Orders 96-230, 96-259, and 500-718 will
be incorporated in OU-5 actions. Order 96-259 was rescinded on January 25, 2008, with the
40
-------
issuance of Order No. R5-2008-0025. Aerojet demonstrated to the RWQCB that they had
complied with the order. Certain contaminated soil areas were also included in OU-5 as a
result of terms included in the 2002 modification of the PCD. The Perimeter Groundwater OU
(OU-5) final ROD for soil and interim ROD for groundwater was finalized on February 11,
2011. The remedy includes ICs prohibiting use of contaminated groundwater and ICs for soil
and soil vapor issues, where appropriate
OU-6 through OU-9: OU-6 through OU-9 will address remediation of soil and portions
of groundwater contamination related to source control located on the Aerojet property.
In addition, this OU-6 ROD addresses soil and soil vapor and restricts access to
contaminated groundwater underneath OU-6. Groundwater and soil studies are currently
underway at OU-7 through OU-9.
2,5 Site Characteristics
The land to the north of Aerojet's property has multiple uses including residential, recreational,
office, commercial, and industrial. The land to the south of Aerojet's property is used for
recreation, ranching, agriculture, and mining, and is also undergoing planning for a mixed use
development. Section 2.6 discusses plans for future land use of the Aerojet property.
2,5,1 Conceptual Site Model
The conceptual site model (CSM) for OU-6 consists of spills and releases to the surface and
subsurface soil from drums, USTs, ASTs, sumps, and ponds. Subsurface contamination,
including contamination in groundwater, is the result of infiltration and percolation of
contamination from releases from ponds, septic tanks, and waste disposal facilities. Surface
soil/sediment, subsurface soil, soil vapor, and groundwater contamination have been identified
within OU-6. The COCs for soil and soil vapor are listed in Table 2-1, the cleanup levels for each
COC in soil are listed in Table 2-2, and COCs in soil vapor are listed in Table 2-3. The CSM for
the human health risk assessment (HHRA) was based on contact and inhalation - including
potential vapor intrusion into structures - and various potential ingestion pathways in residential
scenarios including uptake into garden vegetables. The potential exists for development of these
contaminated areas for various residential, commercial, or industrial uses in the future.
Therefore, the CSM considered current and potential future land use scenarios, which include
resident, commercial worker, construction worker, and future recreation receptors. Because it is
not feasible to individually evaluate every ecological species that may occur on the Aerojet
Superfund Site, ecological receptors were grouped into taxonomic and trophic guilds in the
ecological receptor CSM. Human and ecological receptor CSMs are provided on Figures 2-14
through 2-17, and the conceptual regional geologic model is shown on Figure 2-18.
41
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Table 2-1: Contaminants of Concern in Soil and Soil Vapor
Soil
1,1,2,2-PCA
Benzo(b)fluoranthene
Endrin
Perchlorate
4,4'-DDD
Benzo(k)fluoranthene
Endrin aldehyde
Phenantlirene
4,4'-DDE
Boron
Hexavalent cliromium
Phenol
4,4'-DDT
Cadmium
Ideno(l,2,3-c,d)pyrene
Prowl
Aluminum
Chromium
Iron
Selenium
Antimony
Chrysene
Lead
Silver
Aroclor-1248
Copper
Manganese
TCE
Aroclor-1254
d-BHC
Mercury
Thallium
Aroclor-1260
Dibenz(a,h)anthracene
Molybdenum
Toluene
Barium
Dieldrin
Naphthalene
TPH-D
BEHP
Dimethyl phthalate
NDMA
TPH-Mo
Benzo(a)anthracene
Di-n-octyl phthalate
Nickel
Zinc
Benzo(a)pyrene
DnBP
PCE
Soil Vapor
1,1-DCE
Chloroform
PCE
Toluene
1,2-DCA
cis-l,2-DCE
TCE
Vinyl chloride
Benzene
Notes:
1,1,2,2-PC A = 1,1,2,2-tetrachlorethane
1.1-DCE =l,l-dichloroethene
1.2-DCA =l,2-dichloroethane
4,4'-DDD = 4,4'-dichlorodiphenyldichloroethane
4,4'-DDE = 4,4'-dichlorodiphenyldichloroethene
4,4'-DDT = 4,4'-dichlorodiphenyltrichloroethane
BEHP = bis(2-ethyhexyl)phthalate
cis-l,2-DCE = cis-l,2-dichloroethene
d-BHC = d-benzene hexachloride
DnBP = di-n-butyl phthalate
1,1-DCE, cis-l,2-DCE, and toluene are not shown in Appendix B, as TCE is the main driver for risk, but they are still COCs.
42
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Table 2-2: Performance Standards for Soil3
coc
Residential
Soil CL for
the Protection
of HH
(mg/kg)
Industrial
Soil CL for
the Protection
of HH
(mg/kg)
Source
Soil CL for
the Protection
of GW
(mg/kg)
Source
Soil CL for
the Protection
of Ecological
Receptors
(mg/kg)
Primary Source
1,1,2,2-PCA
0.60
2.7
RSL
--
--
--
--
4,4'-DDD
2.2
9.6
RSL
1.5
DLM
0.021
EcoSSL
4,4'-DDE
1.6
6.8
RSL
1.0
DLM
0.021
EcoSSL
4,4'-DDT
1.9
8.6
RSL
1.0
DLM
0.021
EcoSSL
Aluminum
77,000
1,000,000
RSL
40,976
Background threshold
value (UTL95)
(RCRB soils)
pH<5.5
EcoSSL
54,000
Background threshold
value (UTL95 and Max)
(Xerorthents soils)
Antimony
31
470
RSL
60
DLM
0.42
Background threshold
value (UTL95)
(RCRB soils)
~
~
0.46
Background threshold
value (UTL95)
(Xerorthents soils)
Aroclor-1248
0.24
1.0
RSL
0.034
DLM
0.0072
LANL
Aroclor-1254
0.24
1.0
RSL
0.034
DLM
0.041
LANL
Aroclor-1260
0.24
1.0
RSL
0.034
DLM
0.88
LANL
Barium
15,000
220,000
RSL
10,000
DLM
274
Background threshold
value (UTL95)
(RCRB soils)
~
~
320
Background threshold
value (Max)
(Xerorthents soils)
Benzo(a)antliracene
0.15
2.9
RSL
0.03
DLM
1.1
EcoSSL/high MW
Benzo(a)pyrene
0.015
0.29
RSL
0.029
DLM
1.1
EcoSSL/high MW
43
-------
Table 2-2: Performance Standards for Soil3
coc
Residential
Soil CL for
the Protection
of HH
(mg/kg)
Industrial
Soil CL for
the Protection
of HH
(mg/kg)
Source
Soil CL for
the Protection
of GW
(mg/kg)
Source
Soil CL for
the Protection
of Ecological
Receptors
(mg/kg)
Primary Source
Benzo(b)iluoranthene
0.15
2.9
RSL
0.029
DLM
1.1
EcoSSL/high MW
Benzo(k)iluoranthene
1.5
29
RSL
0.29
DLM
1.1
EcoSSL/high MW
Bis(2-ethylhexyl)phthalate
38
160
RSL
4
DLM
0.02
LANL
Boron
16,000
230,000
RSL
140
DLM
19
Mean CA background
(Kearney Foundation
1996)
Cadmium
4.6
6.4
DTSC Note 3
70
RSL
0.72
Background threshold
value (UTL95)
(RCRB soils)
~
~
~
1.2
Background threshold
value (Max)
(Xerorthents soils)
Chromium
110
110
Background
threshold value
(Max)
(RCRB soils)
500
DLM
110
Background threshold
value (Max)
(RCRB soils)
118
118
Background
threshold value
(UTL95)
(Xerorthents
soils)
500
DLM
118
Background threshold
value (UTL95)
(Xerorthents soils)
Chrysene
15
290
RSL
2.9
DLM
1.1
EcoSSL/high MW
Copper
3,100
47,000
RSL
3,000
DLM
63
Background threshold
value (UTL95 and Max)
(RCRB soils)
~
~
~
76
Background threshold
value (Max)
(Xerorthents soils)
44
-------
Table 2-2: Performance Standards for Soil3
coc
Residential
Soil CL for
the Protection
of HH
(mg/kg)
Industrial
Soil CL for
the Protection
of HH
(mg/kg)
Source
Soil CL for
the Protection
of GW
(mg/kg)
Source
Soil CL for
the Protection
of Ecological
Receptors
(mg/kg)
Primary Source
d-BHC
0.2
DLM
6.4
EPA Region 3
Freshwater Sediment
Screening benchmark,
2014
Dibenz( a,h)anthracene
0.015
0.29
RSL
0.009
DLM
1.1
EcoSSL/high MW
Dieldrin
0.033
0.14
RSL
0.002
DLM
0.0049
EcoSSL
Dimethyl phthalate
--
--
--
313,000
DLM
10
LANL
Di-n-butyl phthalate
6,200
82,000
RSL
700
DLM
0.011
LANL
Di-n-octyl phthalate
620
8,200
RSL
--
--
0.91
LANL
Endrin
18
250
RSL
1.8
DLM
0.0014
LANL
Endrin aldehydeb
18
250
RSL
1.8
DLM
0.0014
LANL
Hexavalent chromium
0.30
6.3
RSL
0.2
Background threshold
value
0.34
LANL
Indeno( 1,2,3-c,d)pyrene
0.15
2.9
RSL
0.029
DLM
1.1
EcoSSL/high MW
Iron
55,000
820,000
RSL
42,000
Background threshold
value (RCRB and
Xerorthents soils)
pH<5.0
EcoSSL
Lead
80
320
DTSCHHRA
Note 3
42
Background threshold
value (UTL95 and Max)
(RCRB soils)
42
Background threshold
value (UTL95 and Max)
(RCRB soils)
80
320
DTSCHHRA
Note 3
23
Background threshold
value (UTL95)
(Xerorthents soils)
23
Background threshold
value (UTL95)
(Xerorthents soils)
45
-------
Table 2-2: Performance Standards for Soil3
coc
Residential
Soil CL for
the Protection
of HH
(mg/kg)
Industrial
Soil CL for
the Protection
of HH
(mg/kg)
Source
Soil CL for
the Protection
of GW
(mg/kg)
Source
Soil CL for
the Protection
of Ecological
Receptors
(mg/kg)
Primary Source
Manganese
1,800
26,000
RSL
1,100
Background threshold
value (Max)
(RCRB soils)
1,100
Background threshold
value (Max)
(RCRB soils)
~
1,500
Background threshold
value (UTL95 and Max)
(Xerorthents soils)
1,500
Background threshold
value (UTL95 and Max)
(Xerorthents soils)
Mercury
9.4
40
RSL
1.2
DLM
0.87
Background threshold
value (UTL95)
(RCRB soils)
9.4
40
RSL
1.2
DLM
0. 13
Background threshold
value (UTL95)
(Xerorthents soils)
Molybdenum
390
5,800
RSL
350
DLM
0.52
Background threshold
value (UTL95)
(RCRB soils)
0.63
Background threshold
value (UTL95)
(Xerorthents soils)
Naphthalene
3.8
17
RSL
0.140
DLM
29
EcoSSL/low MW
NDMA
0.0023
0.045
RSL
0.00003
DLM
--
--
Nickel
1,500
26,000
RSL
120
DLM
75
Background threshold
value (Max)
(RCRB soils)
140
Background threshold
value (UTL95 and
Max) (Xerorthents
soils)
140
Background threshold
value (UTL95 and Max)
(Xerorthents soils)
46
-------
Table 2-2: Performance Standards for Soil3
coc
Residential
Soil CL for
the Protection
of HH
(mg/kg)
Industrial
Soil CL for
the Protection
of HH
(mg/kg)
Source
Soil CL for
the Protection
of GW
(mg/kg)
Source
Soil CL for
the Protection
of Ecological
Receptors
(mg/kg)
Primary Source
PCE
0.55
2.6
Cal-mod RSL
--
--
0.18
LANL
Perchlorate
0.060
820
EPAC
0.06
DLM
0.61 (surface soil)
20.3 (subsurface
soil)
Back-calculated
Phenanthrene
--
--
--
--
--
29
EcoSSL/low MW
Phenol
18,000
250,000
RSL
1
DLM
30
ORNL
Prowl (Pendimethylin)
2,500
33,000
RSL
280
DLM
0.624
EcoSSL
Selenium
6.57
6.57
Background
threshold value
(both RCRB and
Xerorthents
soils)
300
DLM
6.57
Background threshold
value (both RCRB and
Xerorthents soils)
Silver
390
5,800
RSL
1,000
DLM
4.2
EcoSSL
TCE
0.94
6
RSL
--
--
42
LANL
Thallium
0.78
12
RSL
2,000
DLM
1
EcoSSL
~
~
~
3.3
Background threshold
value
(Xerorthents soils)
Toluene
4,900
47,000
RSL
150
DLM
23
LANL
TPH-D
--
--
--
100
DLM
--
--
TPH-Mo
--
--
--
500
DLM
--
--
47
-------
Table 2-2: Performance Standards for Soil3
COC
Residential
Soil CL for
the Protection
of HH
(mg/kg)
Industrial
Soil CL for
the Protection
of HH
(mg/kg)
Source
Soil CL for
the Protection
of GW
(mg/kg)
Source
Soil CL for
the Protection
of Ecological
Receptors
(mg/kg)
Primary Source
Zinc
23,000
350,000
RSL
50,000
DLM
100
Background threshold
value (Max)
(RCRB soils)
89
Background threshold
value (UTL95 and Max)
(Xerorthents soils)
Background soil notes:
Xerorthents soils = These soil types are found in areas of dredge tailings near the American River. Hie soils formed in material that has a high content of gravels and cobbles
derived from mixed rock sources. The material was deposited as tailings during mining activities with slopes ranging from 0 to 50 percent.
RCRB soils = Redding-Coming-Red Bluff soils. Moderately well drained soils that are moderately deep over a cemented hard pan. This unit is found on intermediate and
high terraces, terrace remnants, and the side slopes of terraces in the eastern part of Sacramento Comity. The soils form in alluvium that is derived from mixed rock sources.
For more details on Xerortlient or RCRB soil types, see the OU-6 RI/FS Report (Shaw, 2012).
Notes:
a The soil cleanup levels for protection of human health and ecological receptors also apply to sediments in those areas where a remedial action is being taken.
b Endrin used as a surrogate for endrin aldehyde.
c Perchlorate exposure through the home-gardening pathway (EPA, 2012) (See Appendix F)
d Additional analysis conducted for selenium by Aerojet in 2014.
= No COCs were identified that posed a risk for this pathway.
CL = cleanup level
COC = contaminant of concern
DLM = designated level methodology (Designated Level Methodology' for Waste Classification and Cleanup Level Determination [RWQCB, 1989]J
DTSC HHRA Note 3= California Department of Toxic Substances Control, Human Health Risk Assessment Note 3, July 14, 2014
EcoSSL = ecological soil screening levels (White Paper - Ecological Risk Assessment [Aerojet, 2015])
GW = groundwater
E1H = human health
LANL = Los Alamos National Laboratory
Max = Maximum detected value from Appendix C - Concentrations in Background Soils, BOU Final RI (ERM-West, 2010)
mg/kg = milligrams per kilogram
MW = molecular weight
ORNL = Oak Ridge National Laboratory
RCRB = Redding-Coniing-Red Bluff
RSL = Regional Screening Level (EPA, January 2015) UTL95 = Upper threshold limit (95th percentile) value from Appendix C - Concentrations in Background Soils, BOURI
(ERM-West, 2010)
48
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Table 2-3: Performance Standards for Soil Vapor in Ambient Air
coc
Residential
Use CL
(jig/m3)
Risk Basis
Industrial
Use CL
(jig/m3)
Risk Basis
Benzene
0.084
DTSC HHRA Note 3
July 2014
0.42
DTSC HHRA Note 3
July 2014
Chloroform
0.12
Cancer 10~6 risk level
0.53
Cancer 10~6 risk level
1,1 -Dichloroethene
73
DTSC HHRA Note 3
July 2014
310
DTSC HHRA Note 3
July 2014
cis-1,2-Dichloroethene
7.3
DTSC HHRA Note 3
July 2014
31
DTSC HHRA Note 3
July 2014
1,2-Dichloroethane
0.11
Cancer 10~6 risk level
0.47
Cancer 10~6 risk level
Toluene
310
DTSC HHRA Note 3
July 2014
1,300
DTSC HHRA Note 3
July 2014
Trichloroethene
0.48
Cancer 10~6 risk level
3
Cancer 10~6 risk level
Tetrachloroethene
0.41
DTSC HHRA Note 3
July 2014
2.08
DTSC HHRA Note 3
July 2014
Vinyl chloride
0.031
DTSC HHRA note 3
July 2014
0.16
DTSC HHRA Note 3
July 2014
Notes:
Protective soil vapor levels in subsurface soil are decreased by location- and depth-specific attenuation factors.
DTSC Note 3 regarding modified Air RSLs, July 14, 2014
(ig/m3 = microgram(s) per cubic meter
CL = cleanup level
49
-------
Human Receptors
Current/
Current/
Current/
Future
Future
Current
Future
Secondary
Future
Future
Onsite
Onsite
Onsite
Onsite
Source
Release
Secondary
Release
Exposure
Exposure
Onsite
OfFsite
Comm/ind
Visitor/'
Construction
C onstruction
Medium
Mechanism
Source
Mechanism
Medium
Route
Resident
Resident
Worker
Recreatorb
Worker
Worker
Sumps
Drums
and
ASTs
Ponds
Spills or
Releases
Septic
Tanks
and USTs
Infiltration/
Percolation
Sediment
Soil
Dust
Infiltration/
Percolation
Runoff
Infiltration/
Percolation
Volatile
Emissions
(soil vapor)
Plant
Uptake
Air
11nhalation
Perched''
Regional
Groundwater
" See Figure 3.3-lb for Human Health Exposure Routes related to Treated and Untreated Groundwater
Surface Water
and Sediment
Fish/Shellfish
Ingestion
Perched/
Regional
Groundwater
" See Figure 3.3-lb for Human Health Exposure Routes related to Treated and Untreated Groundwater
Fish/Shellfish
"j Ingestion"
Soil Vapor
Garden
Produce"
~| Ingestion
Ingestion
I
I
I
1
I
I
Dermal Contact
I
1
I
I
I
I
Ingestion
I
1
1
1
I
I
Inhalation
I
I
1
I
I
I
Dermal Contact
1
1
I
I
1
I
Ingestion
C
I
c
Q
c
c
Dermal Contact
C
1
c
0
c
c-
Dust I I Air |
Inhalation
c
0
c
9
c
C
Runoff
Surface Water
and Sediment
Ingestion
1
I
1
1
I
I
Inhalation
I
1
I
1
I
I
Dermal Contact
I
I
I
I
I
I
Inhalation (Indoor)
C
I
c
I
i
I
Inhalation (Outdoor)
C
Q
c
Q
c
c
Notes and Key:
a Projected residential redevelopment at Aerojet is not likely to include land-intensive pathways, such as in-situ gardening. The naturally occurring soil at Aerojet is not suited for this type of activity. Significant land
preparation activities (i.e., addition of topsoil and nutrients) would be required prior to growing fruits or vegetables,
b Since a residential and/or commercial/industrial soil exposure will be evaluated for all the source sites, there is no need to quantify a separate visitor/recreational exposure for all areas. However, a recreational exposure
scenario will be evaluated for Area 39 and Buffalo Creek. Exposures to fish on the Aerojet property are highly unlikely, and are dependent upon the presence of edible species that are of large enough size to be filleted.
ASTs
C
Comm/ind
Source: ERM. 2011
Above-ground Storage Tank
Complete exposure pathway evaluated quantitatively
C ommercial/Industrial
1 Incomplete exposure pathway
USTs Underground Storage Tank
Q Qualitative (not quantitative) evaluation conducted for this potentially complete exposure pathway
^tDSH
2 A \
'*1 PKOf^
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
FIGURE 2-14
Conceptual Site Model
Soil Exposure Pathways for Human Receptors
Operable Unit 6 Record of Decision
ES042114142800SAC
-------
Source
Medium
Ponds
Deluge
Water
Waste
Disposal
Facilities
Human Receptor
Current/
Current/
Current/
Future
Future
Current
Future
Secondary
Future
Future
Onsite
Onsite
Onsite
Onsite
Release
Secondary
Release
Exposure
Exposure
Onsite
Offsite
Comm/Ind
Visitor/
Construction
Construction
Mechanism
Source
Mechanism
Medium
Route
Resident
Resident
Worker
Recreatorc
Worker
Worker
Spills/Leaks
Infiltration/
Percolation
Treated
Groundwater
Untreated
Groundwaterc
Potable and
Non-potable
Use
Volatile
Emissions
Plant
Uptake
Soil Vapor
Garden
Produce3
Fish / Shellfish
Ingestion
Ingestion
H
H
I
I
I
I
Inhalation
H
H
I
I
I
I
Dermal Contact
H
H
I
I
I
I
Ingestion
I
I
I
I
Q
Q
Inhalation
I
I
I
I
0
Q
Dermal Contact
I
I
I
I
Q
Q
Inhalation (Indoor)
C
c
c
I
I
I
Inhalation (Outdoor)
Q
Q
Q
Q
Q
Q
Ingestion
Q
0
I
I
I
l
Discharge to
Surface
Water
Surface Water
and Sediment
Ingestion
Q
I
Q
Q
Q
Q
Inhalation
1
I
I
I
I
I
Dermal Contact
Q
I
Q
c
Q
0
Notes and Key:
a Projected residential redevelopment at Aerojet is not likely to include land-intensive pathways, such as in-situ gardening. The naturally occurring soil at Aerojet is not suited for this type of activity. Significant land
preparation activities (i.e., addition of topsoil and nutrients) would be required prior to growing fruits or vegetables,
b Although construction workers may briefly encounter the shallow water table in some OUs, construction activities in saturated trench conditions are generally avoided and dewatering is performed to avoid work in a wet
and slippery trench. Dermal exposures to contaminants in trench water would be incomplete as steady state absorption and penetration of the skin is unlikely, given short exposure times,
c Recreational exposure will be evaluated on a site-specific basis; if a residential and/or commercial/industrial soil exposure has already been evaluated, there is no need to quantify a separate recreational exposure to soil unless
the property may be transferred solely for recreational use. Exposures to fish on the Aerojet property are highly unlikely, and are dependent upon the presence of edible species that are of large enough size to be filleted,
d No discharge of untreated groundwater to surface water bodies identified in BOU.
C
Comm/Ind
H
I
0
Complete exposure pathway evaluated quantitatively
Commercial/Industrial
Hypothetically complete in absence of institutional controls
Incomplete exposure pathway
Qualitative (not quantitative) evaluation conducted for this potentially complete exposure pathway
Source: ERM. 2011
s A \
sMlj
^ PRO"*4-
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
FIGURE 2-15
Conceptual Site Model
Groundwater and Surface Water Exposure Pathways for Human Receptors
Operable Unit 6 Record of Decision
ES042114142800SAC
-------
Trophic Level -
Functional Group/Feeding Guild -
Secondary
Ecological Receptors
Producers
Primary Consumers
Secondary Consumer
Tertiary Consumers
Aquatic
Vegetation
Trees/
Shrubs
Forbs/
Grasses
Soil
Invertebrates/
Herbaceous
Insects
Benthic and
Aquatic
Invertebrates
Herbivorous
Mammals
Herbivorous/
Granivorous
Birds
Snakes &
Lizards
Turtles
Amphibians
Fish
Omnivorous/'
Insectivorous
Mammals
Omnivorous/
Insectivorous
Birds
Water
Fowl
Raptors
Piscivorous
Mammals
Carnivorous
Mammals
Piscivorous
Birds
Source Release Secondary Release
Medium Mechanism Source Mechanism
Exposure
Medium
Exposure
Route
Surface Water
and Sediment3
Ingestion
I
I
I
I
I
I
I
1
I
1
I
1
I
I
I
I
I
1
Sumps
Dermal Contact
I
I
I
1
I
1
I
I
I
I
I
I
I
I
I
I
I
I
Uptake*
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Infiltration/
Percolation
Perched/'
Regional
Groundwater
Spills or
Releases
Surface
Water
See Figure 3.3-Id for Ecological Exposure Routes related to Treated and Untreated Groundwater
Surface
transport
Surface Water
and Sediment
Ingestion
I
I
I
I
I
I
I
I
I
I
1
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Dermal Contact
Uptake8
I
I
I
I
I
1
I
I
I
I
I
I
1
I
1
I
I
I
Drums &
ASTs
1
Aquatic Food
Chain
Ingestion | NE | - | - | - [ NE | - | - | I | I | I | NE | 1 | I | I | I | I | - | I
Ingestion
I
NE
NE
NE
I
C
C
Q
Q
Q
I
C
C
1
C
I
C
1
Dermal Contact
I
NE
NE
NE
I
C
C
N
N
N
I
C
C
I
C
I
c
I
Uptake8
I
C
C
C
I
-
-
-
-
-
-
-
-
-
-
-
-
-
Dust
Air
Inhalation'' I - | NE | NE | NE | I [ N | N | N | N | N | I | N | N |n|n| n|n'|n
Ponds
Infiltration'
Percolation
Perched'
Regional
Groundwater
See Figure 3.3-Id for Ecological Exposure Routes related to Treated and Untreated Groundwater
Infiltration/
Percolation
Soil
Runoff
Ingestion
NE
I
I
I
NE
c
c
Q
Q
Q
NE
c
c
c
c
c
I
C
and Sediment
Dermal Contact
NE
I
I
I
NE
N
N
N
N
N
NE
N
N
C
N
C
N
c
Uptake3
C
I
I
I
C
-
-
-
-
C
-
-
-
-
-
Septic
Tanks and
USTs
1
Aquatic Food
Chain
Ingestion | NE | - j - | - | NE j - | - | I | I | I | NE | I | 1 |l|l|lj-|l
Volatile
Emissions
Soil Vapor
lnhalationb (Indoor)
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Inhalation (Outdoor)
-
N
N
N
I
Q
I
Q
I
0
I
Q
I
I
Q
1
0
I
Plant and Soil
Invertebrate
Uptake
Terrestrial
Food Chain
| Ingestion | - NE NE NE | - | C | C | Q | I | Q | - | C | C | I | C | 1 | C | I
Notes:
a Uptake applies only to plants, invertebrates, and fish and includes respiration, dermal uptake, and ingestion by these receptors,
b Inhalation includes vapor uptake by plants and respiration by invertebrates
ASTs Above- ground Stora ge Tank
USTs Underground Storage Tank
Designations:
C Complete exposure pathway evaluated quantitatively
I Incomplete exposure pathway
N Negligible or insignificant (though hypothetically potentially complete) pathway that will not be evaluated
NE Exposure route is evaluated as part of the uptake pathway
Q Qualitative (not quantitative) evaluation planned for this potentially complete exposure pathway
Not applicable
Source: ERM, 2011
^0SX
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
PRO^*"
FIGURE 2-16
Conceptual Site Model
Soil Exposure Pathways for Ecological Receptors
Operable Unit 6 Record of Decision
ES04211414 2800SAC
-------
Source
Medium
Deluge
Water
Release
Mechanism
Secondary
Source
Infiltration/
Percolation
Treated
Groundwaterc
Untreated
Groundwater1
Ecological Receptors
Trophic Level -
Producers
Primary Consumers
Secondary Consumer
Tertiary Consumer
Functional Group/Feeding Guild -
Aquatic
Trees/
Forbs/
Soil
Invertebrates/
Herbivorous
Benthic
and Aquatic
Herbivorous
Herbivorous/
Granivorous
Snakes &
Omnivorous/
Insectivorous
Omnivorous/
Insectivorous
Water
Piscivorous
Carnivorous
Piscivorous
Secondary
Vegetation
Shrubs
Grasses
Insects
Invertebrates
Mammals
Birds
Lizards
Turtles
Amphibians
Fish
Mammals
Birds
Fowl
Raptors
Mammals
Mammals
Birds
Release
Mechanism
Potable and
Non-potable
Use
Discharge to
Soil
Volatile
Emissions
Piant
Uptake
Discharge to
Surface
Water
Exposure
Medium
Soil Vapor
Terrestrial
Food Chain
Surface Water
and Sediment
Aquatic
Food-Chain
Exposure
Route
Ingestion
Dermal Contact
Uptake3
Ingestion
Dermal Contact
Uptake3
Ingestion
Dermal Contact
Uptake3
Inhalationb (Indoor)
-
-
_
-
-
-
-
-
-
-
-
-
-
-
-
-
!
Inhalationb (Outdoor)
-
1
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
i !
~j Ingestion"
Ingestion
NE
I
I
I
NE
N
N
N
N
N
NE
N
N
N
N
N
N
N
Dermal Contact
NE
I
I
I
NE
N
N
N
N
N
NE
N
N
N
N
N
N
N
Uptake3
C
I
1
I
C
-
-
-
-
-
C
-
-
-
-
-
-
-
Ingestion
NE | - | - |
NE
-
-
0
Q
NE
N
N
N
N
N
-
N
a Uptake applies only to plants, invertebrates, and fish and includes respiration, dermal uptake, and ingestion by these receptors,
b Inhalation includes vapor uptake by plants and respiration by invertebrates,
c Untreated groundwater does not discharge to surface water within the Boundary Operable Unit.
d Treated groundwater is from the groundwater treatment facilities.
Designations:
C Complete exposure pathway evaluated quantitatively
I Incomplete exposure pathway
N Negligible or insignificant (though hypothetical^ potentially complete) pathway that will not be evaluated
NE Exposure route is evaluated as part of the uptake pathway
Q Qualitative (not quantitative) evaluation planned for this potentially complete exposure pathway
Not applicable
Source: ERM, 2011
i \
| | AEROJET GENERAL CORP.
U.S. EPA REGION IX
SUPERFUND SITE
FIGURE 2-17
Conceptual Site Model
Groundwater and Surface Water Exposure Pathways
for Ecological Receptors
Operable Unit 6 Record of Decision
ES042114142800SAC
-------
Sierra Nevada
Aerojet
Site
Great Valley
Sediments
Ancestral American River Deposits and Dredge Tailings
Hydrostratigraphic Layers A and
Hydrostratigraphic Layers C, D, E and F
Not to Scale - Vertical Component Exaggerated
A
West
> x Coast Ranges \
/"A* s /A s /A N
N/- <
> S \/ > N N \'
V / A ฃ A , ฆ
/A s /A N /A N
v/ ^ ^ ^
Conceptual Regional Geologic Model
Basement Rocks
Not to Scale - Vertical Component Exaggerated
B
West
Conceptual Regional Geologic Model Detail B-B'
Aerojet Site
Brackish to
Saline Aquifer
Sierra Nevada Metamorphic Basement Rocks
A'
East
Figure 2-18: Conceptual Model of Groundwater Structure
59
-------
2,5,2 Overview of OU-6
Since the 1950s, the Aerojet facility has primarily been used for the design, development, and
testing of solid- and liquid-fuel rocket propulsion systems. Industrial activities conducted in
support of this work included solid rocket motor manufacturing, testing, and rehabilitation;
liquid rocket engine manufacturing and testing; and chemical development and manufacturing.
Chemicals used at the site included solvents, propellants, fuels, lubricants, oxidizers, and metals.
The Aerojet Superfund Site is characterized by a relatively flat topographic surface gently
sloping to the west. Most of the onsite topography is dominated by rows of dredge tailings left
from gold mining operations that began in the early 1900s. The dredge tailings consist of
alternating rows of cobble piles separated by low areas filled with silt and clay (slickens).
The depth of dredging ranged from approximately 10 to 90 feet below ground surface (bgs).
The Sacramento area has a mild, subtropical climate with abundant sunshine most of the year.
Climatic information for the area was originally obtained from Monthly Normals of Temperature,
Precipitation, and Heating and Cooling Degree Days 1951-1980, California (National Oceanic
and Atmospheric Administration [NOAA], 1982), and Local Climatological Data 1992,
Annual/Monthly Summary (NOAA, 1993), but has been updated based on data obtained from
the Western Regional Climate Center (www.wrcc.dri.edu). The mean annual temperature in
Sacramento is a relatively mild 62.2 degrees Fahrenheit (ฐF). Maximum average temperatures
during the summer range from 87.1 to 93.1ฐF. Temperatures may occasionally exceed 100ฐF
during hot spells. Winter temperature maximums vary from 54.5 to 60.6ฐF. Average lows in the
winter are 40.2 to 43.7ฐF. Temperatures in the winter rarely drop below freezing. Average annual
precipitation is 18.33 inches, with about 80 percent of the total rainfall occurring from November
through March. The highest rainfall generally occurs in January, which averages 3.80 inches of
precipitation. The driest month is August, averaging only 0.03 inch of rain.
The Aerojet-owned property within the Superfund boundary is presently zoned for industrial use.
The facilities that support industrial operations are grouped into manufacturing areas comprising
multiple buildings. Large areas of undeveloped land are located within and between the
manufacturing areas, and between the property boundaries. The majority of land between active
manufacturing areas and the property boundary served as "buffer space" between operations and
neighboring properties. Approximately 2,600 acres of buffer lands located along the northern and
northwestern property boundaries were removed from the Aerojet Superfund Site in 2002, and
may be developed with a wide variety of land uses, including residential, commercial/industrial,
and recreational.
2,6 Current and Potential Future Land Site and Resources Uses
The Aerojet Superfund Site is designated as a Special Planning Zone (SPZ) with multiple uses
from propulsion systems testing to office use. The SPZ has a provision for future development
under the Sacramento County Land Use Master Plan that would allow for residential use.
The contaminated soil areas of OU-6 and open spaces free of soil contamination, but underlain by
contaminated groundwater, are proposed for development as mixed residential and commercial.
The land immediately adjacent to Aerojet is entirely zoned as heavy and light industrial. The area
farther to the west and south of the El Dorado Freeway (Highway 50) is designated as an
industrial-office park zone. The area north of Highway 50, south of the American River and west
60
-------
of Sunrise Boulevard is zoned approximately 90 percent residential and 10 percent commercial.
The area to the east of Sunrise Boulevard, south of the American River and north of Highway 50,
is approximately 40 percent industrial and 60 percent residential. The American River floodplain
and the edges of the adjacent bluffs are designated as recreational zones. The cities of Rancho
Cordova and Folsom, along with the communities of Carmichael, Fair Oaks and Gold River are
generally fully developed with residential, commercial, and industrial properties. The Assessor's
Parcel Numbers (APNs) for the OU-6 area are all or portions of 072-0231-116, 072-0231-119,
072-0231-120, 072-0231-128, 072-0231-129, and 072-0231-134.
2.6.1 Current Land Uses
Currently, Aerojet uses some portions of the facility for ongoing industrial operations. In
addition, some portions of the facility are leased for use as rangeland where sheep and other
livestock may graze. However, much of the facility is currently vacant and provides habitat for a
wide variety of plant and wildlife species. Properties surrounding Aerojet have been developed
for mixed purposes, and include residential, commercial/industrial, and recreational land uses.
2.6.2 Future Land Uses
Development of the Aerojet facility is planned to include residential, commercial/industrial, and
recreational properties in some areas of OU-6. A large portion of OU-6 will remain undeveloped,
and a portion of the facility will continue to be used by Aerojet for commercial operations.
Figures 2-19 through 2-22 present the current land ownership and current land use plans for
OU-6. Based on a review and analysis of Aerojet's proposed land use plans and municipal
development approvals, planned future land uses have been identified within OU-6. The
proposed Easton project include five boroughs; Easton Place, Hillsborough, Glenborough,
Westborough, and Rio del Oro. Easton Place development and portions of the Westborough
Phase 2 development are located in Sacramento County, and fall within the Aerojet Special
Planning District. Portions of Westborough Phase 2 are located in the City of Rancho Cordova.
Both proposed developments overlap with OU-6 source areas. The future uses anticipated for
Easton Place and Westborough Phase 2 and associated OU-6 remedial considerations are
outlined as follows:
Easton Place (Figure 2-21):
- In January 2009, the Sacramento County Board of Supervisors approved General Plan
and Zoning Amendments, and Tentative Large and Small Lot Subdivision Maps for
Easton Place.
- County approvals for Easton Place allow for the development of a 183-acre transit-oriented
community featuring high-density residential, retail, and commercial office uses.
High-density residential uses are approved for a portion of the Aerojet Superfund Site
affected by OU-6 source areas, including the Administration Area West and former
sewage treatment plant (FSTP) areas.
- Remedial alternatives to address soil and soil vapor impacts at source areas were
evaluated in the OU-6 FS. Potential remedial alternatives include a combination of ICs,
containment (e.g., capping), soil vapor intrusion controls, and excavation to address
61
-------
potential human and ecological health risks in Administration Area West and FSTP areas
where county approvals would allow for high-density residential, mixed-use commercial,
office, and public uses.
- ICs are proposed for Administration Area West and FSTP areas where county approvals
would allow for commercial mixed use, high-density residential, public, and park uses.
ICs would include restricted residential and commercial/industrial land use where
residual COCs would remain in place at concentrations above levels that would allow for
unrestricted use or commercial/industrial use; required soil vapor mitigation measures
until concentrations meet allowable limits for soil vapor; and required health and safety
and materials management procedures for any excavations in areas with residual COCs.
Westborough Phase 2 (Figure 2-22):
- General Corporation has submitted an application to the City of Rancho Cordova for the
development of the Westborough at Easton Specific Plan (Westborough Plan). The
proposed Westborough Phase 2 development is on hold pending the evaluation of source
areas and potential remedial alternatives for OU-6.
- The proposed Westborough Plan envisions the phased development of a 1,695-acre
mixed-use community with low- and medium-density residential uses, retail and
commercial office uses, and natural preserve areas. The Westborough Plan area is
primarily located within the City of Rancho Cordova's Aerojet Special Planning District;
a small portion of the Westborough Plan is located in an area of Sacramento County
proposed for annexation by the City of Rancho Cordova.
- Aerojet proposes residential, commercial mixed-use, and OS uses for OU-6 source areas,
including West Lakes; Line 2; Line 5; Buffalo Creek; and OS Areas 5, 6, and 7. These
areas are currently approved for industrial use only.
- Remedial actions evaluated in the OU-6 FS for the West Lakes; Line 2; Line 5; Buffalo
Creek; and OS Areas 5, 6 and 7 areas include ICs, capping, and excavation to address soil
and soil vapor risks to human health and groundwater, and to address ecological risks.
SVE may also be used to address soil vapor risks.
- Institutional and engineering controls are anticipated for portions of the Line 2 and Line 5
areas proposed for commercial mixed use, OS, and low-density residential uses. ICs
include restricted residential and commercial/industrial use where residual contamination
remains in place, required soil vapor mitigation measures until concentrations meet
allowable limits for soil vapor, and required health and safety and materials management.
62
-------
borough
Easton
Westborough
Phase 2
Westborough
Phase I
Rio delOro
Property owned by
Elliott Homes
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SIJPERFUND SITE
FIGURE 2-19
Ownership and Proposed Use at Aerojet
Operable Unit 6 Record of Decision
Key
Proposed Gen com Developments
Additional Features
I Aerojet Property
Easton Place
Glenborough
Hillsborough
Rio del Oro
Westborough, Phase I
Westborough, Phase II
Prairie City State
Vehicular Recreation Area
Roads
Light Rail
American River
Glenborough
Hillsborough
Property owned by
State of California
Prairie City
I State Vehicular
I Recreation
ES042114142800SAC
-------
borough
Landfill
Gleriborough
Westboroug,
Phase 2
Hillsborough
American River
Groundwater Extraction
Treatment Facility
Prairie City
State Vehicular Recreation Area
(CA Parks Off-Highway Vehicle Division)
Westborough
Phase I
W///////.
Y/////////A
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SIJPERFUND SITE
FIGURE 2-20
Current and Proposed Uses
Operable Unit 6 Record of Decision
Key
General Features
I I Proposed Developments
Roads
PC5VRA (in continued Use)
Light Rail
American River
Soil Medium Operable Units
OU6 Boundary
Area 39 (evaluated in OU6 Remedial Investigation; now part of OU7)
ES042114142800SAC
-------
| MilPft
N
\
1
A
0
0.1
0.2
A
Key
General Features
I I Aerojet Boundary
i_jght Rail
Operable Units
| OU5 Perimeter Groundwater
(Soil Medium)
OU6 Boundary
Proposed Land Uses
Commercial Mixed Use
ฆ commercial
Community Resource
High Density Residential
Low Density Residential
Medium Density Residential
Major Road
Office
Open Space
Open Space/Alder Creek
Public/Quasi -Public
Park
Paikway
School
U.S. EPA REGION IX
AEROJET GENERAL CORP.
\j SIJPERFUND SITE
FIGURE 2-21
Proposed Developments - Easton Place
Operable Unit 6 Record of Decision
Former
Sewage
Treatment
Plant
ES042114142800SAC
-------
Key
General Features
I I Aerojet Boundary
. Light Rail
Operable Units
I' ::l OU5 Perimeter Groundwater
(Soil Medium)
~ OU6 Boundary
~ OU7 Island
I OU9 Central
i \
Proposed Land Uses
Commercial Mixed Use
i Commercial
Community Resource
High Density Residential
Low Density Residential
Medium Density Residential
Major Road
Open Space
Open Space/Alder Creek
Public/Quasi-Public
^Park
Parkway
School
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SIJPERFUND SITE
FIGURE 2-22
Westborough Phase 2
Operable Unit 6 Record of Decision
ES042114142800SAC
-------
Summary of Site Risks
Human health and ecological risk assessments were performed to identify and estimate potential
risks to people and the environment from contamination of soil, soil vapor, sediment, and surface
water at the eight MAs and OS areas encompassed by OU-6. The HHRA evaluated the use of
untreated groundwater for residential supply and the potential for migration of VOCs from soil,
soil vapor, and groundwater into indoor and ambient air, under both current and future land use
scenarios. The SLERA evaluated the potential ecological risks due to exposure to constituents in
soil, soil vapor, sediment, and surface water by aquatic and terrestrial habitat and receptors
(biota) of concern. The results of the SLERA are presented in Section 2.7.5. The conclusions
from the two risk assessments provide the basis for taking action, and identify the contaminants
and exposure pathways that need to be addressed by the remedial action. This information is
presented and summarized in Appendix B.
The response action selected in this ROD is necessary to protect public health, welfare, or the
environment from actual or threatened releases of hazardous substances, pollutants, or
contaminants into the environment.
This section of the ROD summarizes the results of the HHRA and SLERA for OU-6.
2.7.1 Identification of Contaminants of Concern
COCs are chemicals that are present at concentrations high enough to present a risk to human
health or ecological receptors. Based on the data collected during the RI, COCs were identified that
drive the need for remedial action. Chemical data from each media were compared with human
health and ecological screening levels and screening levels for the protection of groundwater, and
considered potential COCs if they exceeded these levels. Results of the background screening
demonstrated that five of the metals (aluminum, arsenic, manganese, thallium, and vanadium) are
statistically comparable to background and were not considered potential COCs.
The data for the OU-6 risk assessments were obtained from two Aerojet databases, the OU-6
database and the historical database. The OU-6 database contains analytical data for soil,
sediment, soil vapor, surface water, and groundwater samples collected from areas within OU-6
between July 2005 and April 2007. The historical database contains analytical data for soil, soil
vapor, and groundwater samples collected during site investigations between January 1990 and
June 2006. Due to age of the historical soil vapor data and because the analyses included only a
selected number of VOCs with detection limits much higher than present, the OU-6 RI included
re-sampling of soil vapor for VOCs between 2005 and 2007. The VOC soil vapor data collected
during the OU-6 RI are more representative and accurate than the historical soil vapor data;
and, therefore, only soil vapor data collected during the OU-6 RI were evaluated in the risk
assessments. However, as noted later in Section 2.8, further delineation will be conducted during
the remedial design phase.
2.7.2 Exposure Assessment
Exposure refers to the potential contact of an individual with a contaminant. The exposure
assessment evaluates the magnitude, frequency, duration, and route of potential exposure.
71
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This section describes which populations may be exposed, the exposure pathways, and how
much exposure to the contaminants is present. A complete discussion of all the scenarios and
exposure pathways is presented in the final human health and ecological risk assessment
(HHERA) for OU-6 (ERM, 2011).
Exposure pathways for the human health risk evaluation for soil (0 to 12 feet bgs) include the
following:
Direct contact (incidental ingestion and dermal contact)
Inhalation of fugitive dust
Volatilization of VOCs from soil and soil vapor into ambient (outdoor and indoor) air
Exposure pathways for the human health risk evaluation for sediment (generally 0 to 1 feet bgs)
include the following:
Dermal contact with sediment during recreational (wading) activity
Incidental ingestion of sediment during recreational (wading) activity
Exposure pathways for the human health risk evaluation for surface water include the following:
Dermal contact with surface water during recreational activity
Incidental ingestion of surface water during recreational activity
Exposure pathways for the human health risk evaluation for groundwater include the following:
Use of groundwater for future hypothetical residential water supply
Migration of VOCs from groundwater through the unsaturated zone into ambient
(outdoor and indoor) air
Contact with groundwater during excavation or other intrusive activities
For each selected contaminant of potential concern (COPC) for each media, the detected
concentration at each location and depth was used in the calculation of estimated hazards and
incremental cancer risks, resulting in a sample-by-sample risk estimate. For soil, analytical
results from samples collected from 0 to 12 feet bgs were used as potential exposure point
concentrations. Soil vapor analytical results from samples collected from 10 to 40 feet bgs were
used as potential fate and transport model inputs for deriving ambient (indoor and outdoor) air
exposure point concentrations. For indoor and outdoor air, concentrations were based on
modeling of individual location-depth concentrations from bulk soil (outdoor air), soil vapor
measurements (both indoor and outdoor air), and groundwater measurements (indoor air).
To understand the areal extent of potential risk and to create maps of these potential risks, part of
the HHRA methodology was to calculate risk estimates based on the chemical results at each
sampling location. This "point-by-point" approach was followed because at the time the HHRA
was being prepared, a development plan was not formally established for the entire OU-6, and
there was potential variability in the exposure units by which future receptors could be exposed.
This approach is representative in that receptors are not exposed to concentrations from a
single location for the entire duration of their exposure period, especially in the case of outdoor
air exposures. Receptor behavior is more likely to result in composite exposures to multiple
locations and chemical concentrations.
72
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2.7.3 Toxicity Assessment
Several EPA and Cal-EPA sources were used to obtain toxicity criteria (i.e., cancer slope factors
and noncarcinogenic reference doses) in this risk assessment. The following sources for selecting
toxicity criteria were used, and EPA (2003a) hierarchy was generally followed:
Cal-EPA Office of Environmental Health Hazard Assessment (OEHHA), Toxicity
Criteria Database
Integrated Risk Information System (IRIS)
EPA's Provisional Peer-Reviewed Toxicity Values
National Center for Environmental Assessment (NCEA, or other current EPA sources)
Health Effects Assessment Summary Tables (HEAST)
EPA criteria documents (e.g., drinking water criteria documents, drinking water Health
Advisory summaries, ambient water quality criteria documents, and air quality criteria
documents)
Agency for Toxic Substances and Disease Registry (ATSDR) toxicological profiles
EPA's Environmental Criteria and Assessment Office
The exception to the hierarchy is if both Cal-EPA and EPA toxicity criteria exist for a given
COPC, the most conservative value was used.
The most recent RSLs (January 2015) and DTSC's HHRANote 3 (July 2014) are included in
this ROD. DTSC's HHRA Note 3 adopts EPA RSLs.
Table 2-4 provides the noncancer toxicity criteria, and Table 2-5 provides the carcinogenic
toxicity criteria used in the HHRA.
This Risk Assessment evaluated petroleum hydrocarbon mixtures through quantitative
evaluation of the risks associated with exposure to petroleum constituents such as benzene,
toluene, ethylbenzene, and xylenes (BTEX) and PAHs.
Quantifying lead exposure is accomplished using different procedures than for other COPCs.
Unlike for other chemicals, substantial evidence has been compiled allowing correlation of
cause-and-effect relationships in humans with blood concentrations of lead. DTSC's Lead Risk
Assessment Spreadsheet model (Version 7) (DTSC, 2011) was incorporated into the assessment.
In July 2014, DTSC released HHRA Note 3 that establishes a revised toxicity assessment
approach, using an incremental increase of 1 micrograms per deciliter (|ig/dL) in blood lead as a
benchmark. This benchmark is a more conservative approach to the assessment of lead
exposures, resulting in a change for residential and commercial receptors from 150 and
3,500 mg/kg to 80 and 320 mg/kg, respectively.
2.7.4 Risk Characterization
For carcinogens, risks are generally expressed as the probability of an individual developing
cancer over a lifetime as a result of exposure to site-related contaminants. This is described as
"excess lifetime cancer risk" because it is in addition to the risk of cancer from other causes.
Risk is expressed in scientific notation, that is, 1E-06 or 1 x 10 6. A risk result of 1E-06 means an
73
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individual has a 1 in 1,000,000 chance of developing cancer from site-related exposure. The
chance of an individual developing cancer from all other causes has been estimated to be as high
as one in three. The EPA's generally acceptable risk range for site-related exposures is between
1E-06 and 1E-04 (in effect, 1 in 1,000,000 to 1 in 10,000). An excess lifetime cancer risk greater
than 1 in 10,000 (1E-04) is the point at which action is generally required at a site. The lxlO"6
risk level is used as the point of departure for determining remediation action goals; it expresses EPA's
preference for remedial actions that reduce risks to the most protective end of the risk range.
The potential for noncarcinogenic effects is evaluated by comparing an exposure level, over a
specified time period (e.g., a lifetime), with a reference dose (RfD), a safe dose including safety
factors where no adverse effects would be expected. The exposure level is also expressed as an
average daily exposure dose. This comparison represents a ratio of the exposure dose to the RfD,
and is called the hazard quotient (HQ). A HQ of less than 1 means the receptor (individual) is
exposed to a dose less than the RfD and is not expected to experience any harmful effects. The
hazard index (HI) is the sum of all the HQs that affect the same target organ (i.e., liver) or organ
system. HQs are combined for pollutants that cause adverse effects by the same toxic mechanism.
An HI less than 1 means that, based on the sum of HQs from different contaminants and exposure
routes, toxic effects are unlikely.
Tables 2-6 through 2-9 provide risk, HI, and lead results by exposure area for exposure to surface
water, groundwater, soil and sediment, and soil vapor, respectively. Lead concentrations in soil
and sediment are also provided in Table 2-8. The following subsections summarize the risk,
hazard, and blood lead results by media.
2,7,4,1 Surface Water
The exposure pathways evaluated for surface water include ingestion of surface water during
recreational use and dermal contact with surface water during recreational use. Three exposure
areas were evaluated for exposure to surface water. These include the following:
Administration Area (East and West) (the east and west Administration Area were
evaluated separately for soil and soil vapor exposure but grouped into one exposure area
for surface water and groundwater exposure)
West Lakes, Line 2, Line 5 North Area
Chemical Plant 2
Residential exposure to surface water in the exposure areas indicated His are less than the target
HI of 1. The concentration of lead in surface water exceed the California regulatory action level
for lead of 15 micrograms per liter (|ig/L) at two of the three exposure areas. The incremental
lifetime cancer risk (ILCR) is below the cumulative risk level of 1E-06 at two of the three
exposure areas. At West Lakes, Line 2, and Line 5 North Area, the ILCR of 2E-06 slightly
exceeds the lower end of the risk management range of 1E-06. The primary contributor to the
risk is BEHP (Table 2-6).
74
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Inhalation - Chronic Inhalation
- Subchronic
Oral'1' - Chronic
Oral11'
Subchronic
Dermal
Inhalation - Chronic
Inhalation
- Subchronic
Oral'1' - Chronic
Oral11'
Subchronic
Dermal
CAS
Oral
Dermal
% GI Chronic
CAS
Oral
Derma
% GI Chronic
Chemical
Number
Value5
Reference
Value5
Reference
Value5
Reference
BIO
ABS(2)
ABS Value
Chemical
Number
Value5
Reference
Value5
Reference
Value5
Reference
BIO
ABS(2)
ABS Value
Aluminum
7429-90-5
1.4 E-3
PPRTV
44 E-3
Chronic (4)
1.0 E+0
PPRTV
1.0 E+0
Chronic
1.0
NA
cis-l,2-Dichloroethene
156-59-2
1.0 E-2
route-to-route
1.0 E-2
Chronic
1.0 E-2
PPRTV
1.0 E-2
Chronic
1.0
NA
Antimony
7440-36-0
40E-4
route-to-route
40 E-4
Chronic
40 E-4
USEPA, 2008
40 E-4
Chronic
1.0
NA
15% 6.0 E-5
Cumene
98-82-8
1.1 E-l
USEPA 2008
1.1 E-l
Chronic
1.0 E-l
USEPA 2008
1.0 E-l
Chronic
1.0
NA
Arsenic
7440-38-2
8.6 E-6
OEHHA, 2008
8.6 E-6
Chronic
3.0 E-4
USEPA, 2008
3.0 E-4
Chronic
0.6
0.03
Cyclohexane
110-82-7
1.7 E+0
USEPA, 2008
1.7 E+0
Chronic
1.7 E+0
route-to-route
1.7 E+0
Chronic
1.0
NA
Barium
7440-39-3
1.4 E-4
USEPA, 1997
1.4 E-4
Chronic
2.0 E-l
USEPA, 2008
2.0 E-l
Chronic
1.0
NA
7% 1.4 E-2
delta-BHC
319-86-8
3.0 E-4
route-to-route
3.0 E-4
Chronic
3.0 E-4
]PA, 2008 Lindane surrog,
3.0 E-4
Chronic
1.0
0.04
Beryllium
7440-41-7
5.7 E-6
USEPA, 2008
5.7 E-6
Chronic
2.0 E-3
USEPA, 2008
2.0 E-3
Chronic
1.0
NA
0.7% 1.4 E-5
Dibenz (a,h) anthracene
53-70-3
NA
NA
NA
NA
Chronic
1.0
0.13
Boron
5.7 E-3
USEPA, 1997
5.7 E-3
Chronic
2.0 E-l
USEPA, 2008
2.0 E-l
Chronic
1.0
NA
Dibromochloromethane
2.0 E-2
route-to-route
2.0 E-2
Chronic
2.0 E-2
USEPA, 2008
2.0 E-2
Chronic
1.0
NA
Cadmium
7440-43-9
1.0 E-3
route-to-route
1.0 E-3
Chronic
1.0 E-3
USEPA, 2008
1.0 E-3
Chronic
1.0
0.001
2.5% 2.5 E-5
Dichlorodifluoromethane
5.7 E-2
USEPA, 1997
5.7 E-2
Chronic
2.0 E-l
USEPA, 2008
2.0 E-l
Chronic
1.0
NA
Cadmium - W ater
7440-43-9
5.0% 5.0 E-5
Dieldrin
60-57-1
5.0 E-5
route-to-route
5.0 E-5
Chronic
5.0 E-5
USEPA, 2008
5.0 E-5
Chronic
1.0
0.04
Chromium
16065-83-1
1.5 E+0
route-to-route
1.5 E+0
Chronic
1.5 E+0
USEPA, 2008P)
1.5 E+0
Chronic
1.0
NA
1.3% 2.0 E-2
Di-n-butyl phthalate
84-74r2
1.0 E-l
route-to-route
1.0 E-l
Chronic
1.0 E-l
USEPA 2008
1.0 E-l
Chronic
1.0
0.1
Chromium VI
18540-29-9
2.2 E-6
USEPA, 2008
2.2 E-6
3.0 E-3
USEPA, 2008
3.0 E-3
Chronic
1.0
NA
2.5% 7.5 E-5
Endosulfan I
115-29-7
6.0 E-3
route-to-route
6.0 E-3
Chronic
6.0 E-3
USEPA, 2008
6.0 E-3
Chronic
1.0
0.10
Cobalt
7440-48-4
5.7 E-6
PPRTV
5.7 E-6
Chronic
2.0 E-2
PPRTV
2.0 E-2
Chronic
1.0
NA
Endosulfan II
115-29-7
6.0 E-3
route-to-route
6.0 E-3
Chronic
6.0 E-3
USEPA, 2008
6.0 E-3
Chronic
1.0
0.10
Copper
7440-50-8
3.7 E-2
route-to-route
3.7 E-2
Chronic
3.7 E-2
USEPA 1997b
3.7 E-2
Chronic
1.0
NA
Endrin
72-20-8
3.0 E-4
route-to-route
3.0 E-4
Chronic
3.0 E-4
USEPA, 2008
3.0 E-4
Chronic
1.0
0.04
Iron
7439-89-6
NA
NA
7.0 E-l
PPRTV
7.0 E-l
1.0
NA
Ethanol
64-17-5
5.0 E-l
route-to-route
5.0 E-l
Chronic
5.0 E-l
USEPA 2008
5.0 E-l
Chronic
1.0
NA
Lead
7439-92-1
NA
NA
NA
NA
Chronic
0.44
NA
Ethylbenzene
100-41-4
2.9 E-l
USEPA 2008
2.9 E-l
Chronic
1.0 E-l
USEPA 2008
1.0 E-l
Chronic
1.0
NA
Lithium
7439-93-2
NA
NA
2.0 E-2
R9PRG
2.0 E-2
Chronic
1.0
NA
Fluoranthene
206-44-0
40 E-2
route-to-route
40 E-2
Chronic
40 E-2
USEPA 2008
4.0 E-2
Chronic
1.0
0.13
Manganese
7439-96-5
1.4 E-5
USEPA, 2008
1.4 E-5
Chronic
2.4 E-2
USEPA, 2008
2.4 E-2
Chronic
1.0
NA
40% 9.6 E-4
Fluorene
40 E-2
route-to-route
40 E-2
Chronic
40 E-2
USEPA, 2008
4.0 E-2
Chronic
1.0
0.13
Mercury
7439-97-6
8.6 E-5
USEPA, 2008
8.6 E-5
Chronic
3.0 E-4
USEPA, 2008
3.0 E-4
Chronic
1.0
NA
7.0% 2.1 E-5
Freonll
75-69-4
5.7 E-2
USEPA, 1997
5.7 E-2
Chronic
2.0 E-l
USEPA, 2008
2.0 E-l
Chronic
1.0
NA
Molybdenum
7439-98-7
5.0 E-3
route-to-route
5.0 E-3
Chronic
5.0 E-3
USEPA, 2008
5.0 E-3
Chronic
1.0
NA
Freonll3
76-13-1
8.6 E+0
USEPA, 1997
8.6 E+0
Chronic
3.0 E+l
USEPA, 2008
3.0 E+l
Chronic
1.0
NA
Nickel
7440-02-0
1.4 E-5
OEHHA, 2008
1.4 E-5
Chronic
2.0 E-2
USEPA, 2008
2.0 E-2
Chronic
1.0
NA
4% 8.0 E-4
Freonl2
75-71-8
5.7 E-2
USEPA 1997b
5.7 E-2
Chronic
2.0 E-l
USEPA 2008
2.0 E-l
Chronic
1.0
NA
Nitrate as N03
NA
NA
1.6 E+0
USEPA, 2008
1.6 E+0
Chronic
1.0
NA
gamma-BHC (Lindane)
58-89-9
3.0 E-4
route-to-route
3.0 E-4
Chronic
3.0 E-4
USEPA, 2008
3.0 E-4
Chronic
1.0
0.04
Nitrate plus Nitrite (as N)
NA
NA
1.6 E-l
19PRG nitrite as surrogate
1.6 E-l
Chronic
1.0
NA
gamma-chlordane
57-74-9
2.0 E-4
USEPA, 2008
2.0 E-4
Chronic
5.0 E-4
USEPA, 2008
5.0 E-4
Chronic
1.0
0.04
Nitrite as N02
NA
NA
1.6 E-l
R9PRG
1.6 E-l
Chronic
1.0
NA
Heptachlor
76-44-8
5.0 E-4
route-to-route
5.0 E-4
Chronic
5.0 E-4
USEPA, 2008
5.0 E-4
Chronic
1.0
0.04
Perchlorate
14797-73-0
7.0 E-4
route-to-route
7.0 E-4
Chronic
7.0 E-4
USEPA 2008
7.0 E-4
Chronic
1.0
NA
Heptachlor epoxide
1024-57-3
1.3 E-5
route-to-route
1.3 E-5
Chronic
1.3 E-5
USEPA, 2008
1.3 E-5
Chronic
1.0
0.04
Selenium
7782-49-2
5.0 E-3
route-to-route
5.0 E-3
Chronic
5.0 E-3
USEPA, 2008
5.0 E-3
Chronic
1.0
NA
Heptane
142-82-5
2.0 E-l
Hexane as surrogate
2.0 E-l
Chronic
1.1 E+l
Hexane as surrogate
1.1 E+l
Chronic
1.0
0.1
Silver
7440-22-4
5.0 E-3
route-to-route
5.0 E-3
Chronic
5.0 E-3
USEPA, 2008
5.0 E-3
Chronic
1.0
NA
4% 2.0 E-4
Hexachlorobut adiene
1.0 E-3
route-to-route
1.0 E-3
Chronic
1.0 E-3
PPRTV
1.0 E-3
Chronic
1.0
NA
Strontium
6.0 E-l
route-to-route
6.0 E-l
Chronic
6.0 E-l
USEPA, 2008
6.0 E-l
Chronic
1.0
NA
Hexane
110-54-3
2.0 E-l
USEPA 1997b
2.0 E-l
Chronic
1.1 E+l
R9PRG
1.1 E+l
Chronic
1.0
0.1
Thallium
7446-18-6
6.6 E-5
route-to-route
6.6 E-5
Chronic
6.6 E-5
USEPA, 2008
6.6 E-5
Chronic
1.0
NA
Hexanedioic Acid, dioctyles
103-23-1
6.0 E-l
route-to-route
6.0 E-l
Chronic
6.0 E-l
USEPA 2008
6.0 E-l
Chronic
1.0
0.1
Titanium
7440-32-6
8.6 E-3
NCEA
8.6 E-3
Chronic
40 E+0
NCEA
4.0 E+0
Chronic
1.0
NA
I ndeno(l ,2,3- cd) pyrene
193-39-5
NA
NA
NA
NA
Chronic
1.0
0.13
Vanadium
7440-62-2
5.0 E-3
route-to-route
5.0 E-3
Chronic
5.0 E-3
NCEA
5.0 E-3
Chronic
1.0
NA
2.6% 1.3 E-4
m,p-Xylene
1330-20-7
2.9 E-2
USEPA, 2008
2.9 E-2
Chronic
2.0 E-l
USEPA, 2008
2.0 E-l
Chronic
1.0
NA
Zinc
7440-66-6
3.0 E-l
route-to-route
3.0 E-l
Chronic
3.0 E-l
USEPA, 2008
3.0 E-l
Chronic
1.0
NA
Methyl tert-butyl ether
1634-04-4
8.6 E-l
USEPA 2008
8.6 E-l
Chronic
8.6 E-l
route-to- route
8.6 E-l
Chronic
1.0
NA
1,1,1-T richloroethane
71-55-6
1.4 E+0
USEPA 2008
1.4 E+0
Chronic
2.0 E+0
USEPA, 2008
2.0 E+0
Chronic
1.0
NA
Methylene chloride
75-09-2
8.6 E-l
USEPA 1997b
8.6 E-l
Chronic
6.0 E-2
USEPA, 2008
6.0 E-2
Chronic
1.0
NA
1,1,2,2-T etrachloroethane
79-34-5
6.0 E-2
route-to-route
6.0 E-2
Chronic
6.0 E-2
USEPA, 2008
6.0 E-2
Chronic
1.0
NA
m-Xylene
2.9 E-2
USEPA, 2008
2.9 E-2
Chronic
2.0 E-l
USEPA, 2008
2.0 E-l
Chronic
1.0
NA
1,1,2-T richloroethane
79-00-5
4.0 E-3
route-to-route
4.0 E-3
Chronic
4.0 E-3
USEPA, 2008
40 E-3
Chronic
1.0
NA
Naphthalene
91-20-3
8.6 E-4
USEPA, 2008
8.6 E-4
Chronic
2.0 E-2
USEPA, 2008
2.0 E-2
Chronic
1.0
0.13
1,1-Dichloroethane
75-34-3
2.0 E-l
route-to-route
2.0 E-l
Chronic
2.0 E-l
PPRTV
2.0 E-l
Chronic
1.0
NA
n-Butylbenzene
1.0 E-2
route-to-route
1.0 E-2
Chronic
1.0 E-2
PPRTV
1.0 E-2
Chronic
1.0
NA
1,1 -Dichloroethene
75-35-4
2.0 E-2
OEHHA 2008
2.0 E-2
Chronic
5.0 E-2
USEPA 2008
5.0 E-2
Chronic
1.0
NA
N-Nitrosodimethylamine
62-75-9
8.0 E-6
route-to-route
8.0 E-6
Chronic
8.0 E-6
PPRTV
8.0 E-6
Chronic
1.0
0.10
1,2,4-T rimethylbenzene
95-63-6
2.0 E-3
PPRTV
2.0 E-3
Chronic
2.0 E-3
PPRTV
2.0 E-3
Chronic
1.0
NA
o-Xylene
95-47-6
2.9 E-2
USEPA 2008
2.9 E-2
Chronic
2.0 E-l
USEPA 2008
2.0 E-l
Chronic
1.0
NA
1,2-Dichlorobenzene
6.9 E-3
NCEA
6.9 E-3
Chronic
9.0 E-2
USEPA, 2008
9.0 E-2
Chronic
1.0
NA
PCB-1248
12672-29-6
2.0 E-5
route-to-route
2.0 E-5
Chronic
2.0 E-5
USEPA 2008
2.0 E-5
Chronic
1.0
0.14
1,2-Dichloroethane
107-06-2
1.4 E-3
NCEA
1.4 E-3
Chronic
2.0 E-2
NCEA
2.0 E-2
Chronic
1.0
NA
PCB-1254
11097-69-1
2.0 E-5
route-to-route
2.0 E-5
Chronic
2.0 E-5
USEPA, 2008
2.0 E-5
Chronic
1.0
0.14
1,2-Dichloroethene (cis/trans)
1.0 E-2
route-to-route
1.0 E-2
Chronic
1.0 E-2
PPRTV
1.0 E-2
Chronic
1.0
NA
PCB-1260
11096-82-5
2.0 E-5
route-to-route
2.0 E-5
Chronic
2.0 E-5
USEPA, 2008
2.0 E-5
Chronic
1.0
0.14
1,3,5-T rimethylbenzene
108-67-8
1.7 E-3
PPRTV
1.7 E-3
Chronic
5.0 E-2
PPRTV
5.0 E-2
Chronic
1.0
NA
Pendimethalin (Prowl)
40487-42-1
40 E-2
route-to-route
40 E-2
Chronic
40 E-2
USEPA 2008
4.0 E-2
Chronic
1.0
0.10
1,3-Butadiene
106-99-0
5.7 E-4
USEPA 2008
5.7 E-4
Chronic
5.7 E-4
Route to route
5.7 E-4
Chronic
1.0
NA
Pentachlorophenol
87-86-5
3.0 E-2
route-to-route
3.0 E-2
Chronic
3.0 E-2
USEPA 2008
3.0 E-2
Chronic
1.0
0.10
1,4-Dichlorobenzene
2.3 E-l
USEPA, 2008
2.3 E-l
Chronic
3.0 E-2
NCEA
3.0 E-2
Chronic
1.0
NA
Phenanthrene
85-01-8
3.0 E-2
pyrene as surrogate
3.0 E-2
Chronic
3.0 E-2
pyrene as surrogate
3.0 E-2
Chronic
1.0
0.13
1/tDioxane
123-91-1
8.6 E-l
OEHHA, 2008
8.6 E-l
Chronic
NA
NA
1.0
NA
Phenol
108-95-2
5.7 E-2
OEHHA, 2008
5.7 E-2
Chronic
3.0 E-l
USEPA, 2008
3.0 E-l
Chronic
1.0
0.10
2,2,4-T rimethylpent ane
540-84-1
2.9 E-2
surrogate: xylene
2.9 E-2
Chronic
2.0 E-l
surrogate: xylene
2.0 E-l
Chronic
1.0
NA
p-I sopropy ltoluene
NA
NA
NA
NA
1.0
NA
2,3,7,8-TCDD TEQ
1746-01-6
NA
NA
NA
NA
1.0
0.03
Propylbenzene
103-65-1
1.0 E-2
route-to-route
1.0 E-2
Chronic
1.0 E-2
NCEA
1.0 E-2
Chronic
1.0
NA
2-Butanone (Methyl ethyl k<
78-93-3
1.4 E+0
USEPA, 2008
1.4 E+0
Chronic
6.0 E-l
USEPA, 2008
6.0 E-l
Chronic
1.0
NA
p-Xylene
2.9 E-2
USEPA, 2008
2.9 E-2
Chronic
2.0 E-l
USEPA, 2008
2.0 E-l
Chronic
1.0
NA
2-Hexanone
591-78-6
8.6 E-l
IPA 2008; MIBK Surrog
9.0 E-l
Chronic
8.0 E-2
PA, 1997; MIBK as surrog
8.0 E-2
Chronic
1.0
NA
Pyrene
3.0 E-2
USEPA, 2008
3.0 E-2
Chronic
3.0 E-2
USEPA, 2008
3.0 E-2
Chronic
1.0
0.13
2-Methylnaphthalene
NA
NA
4.0 E-3
USEPA, 2008
40 E-3
Chronic
1.0
0.13
sec-Buty lbenzene
1.0 E-2
route-to-route
1.0 E-2
Chronic
1.0 E-2
PPRTV
1.0 E-2
Chronic
1.0
NA
2-Propanol
67-63-0
2.6 E-3
R9PRG
2.6 E-3
Chronic
1.0 E-l
A 2007c, butanol as surro
1.0 E-l
Chronic
1.0
NA
Styrene
100-42-5
2.6 E-l
OEHHA, 2008
2.6 E-l
Chronic
2.0 E-l
USEPA, 2008
2.0 E-l
Chronic
1.0
NA
4,4'-DDD
72-54-8
NA
NA
NA
NA
1.0
0.03
T etrachloroethene
127-18-4
1.0 E-2
route-to-route
1.0 E-2
Chronic
1.0 E-2
USEPA, 2008
1.0 E-2
Chronic
1.0
NA
4,4'-DDE
72-55-9
NA
NA
NA
NA
1.0
0.03
T etrahy drofuran
109-99-9
8.6 E-2
NCEA
8.6 E-2
Chronic
2.0 E-l
NCEA
2.0 E-l
Chronic
1.0
NA
4,4'-DDT
50-29-3
5.0 E-4
route-to-route
5.0 E-4
Chronic
5.0 E-4
USEPA, 2008
5.0 E-4
Chronic
1.0
0.03
Toluene
108-88-3
8.6 E-2
OEHHA 2008
8.6 E-2
Chronic
8.0 E-2
USEPA 2008
8.0 E-2
Chronic
1.0
NA
4-Ethyltoluene
622-96-8
2.9 E-2
xylene surrogate
2.9 E-2
Chronic
2.0 E-l
xylene surrogate
2.0 E-l
Chronic
1.0
NA
trans-1,2-Dichloroethene
1.7 E-2
PPRTV
1.7 E-2
Chronic
2.0 E-2
USEPA, 2008
2.0 E-2
Chronic
1.0
NA
4-Methy 1-2-pent anone
8.6 E-l
USEPA, 2008
8.6 E-l
Chronic
8.0 E-2
USEPA, 2008
8.0 E-2
Chronic
1.0
NA
T richloroethene
79-01-6
1.7 E-l
OEHHA, 2008
1.7 E-l
Chronic
3.0 E-4
NCEA
3.0 E-4
Chronic
1.0
NA
4-Methylphenol
106-44-5
5.0 E-3
route-to-route
5.0 E-3
Chronic
5.0 E-3
USEPA, 1997b
5.0 E-3
Chronic
1.0
0.10
T richlorofluoromethane
5.7 E-2
USEPA, 1997
5.7 E-2
Chronic
2.0 E-l
USEPA, 2008
2.0 E-l
Chronic
1.0
NA
Acetone
67-64-1
9.0 E-l
route-to-route
9.0 E-l
Chronic
9.0 E-l
USEPA, 2008
9.0 E-l
Chronic
1.0
NA
Vinyl Chloride
75-01-4
2.9 E-2
USEPA 2008
2.9 E-2
Chronic
3.0 E-3
USEPA 2008
3.0 E-3
Chronic
1.0
NA
Acrolein
107-02-8
5.7 E-6
USEPA, 2008
5.7 E-6
Chronic
5.0 E-4
USEPA, 2008
5.0 E-4
Chronic
1.0
NA
Xylenes (total)
1330-20-7
2.9 E-2
USEPA, 2008
2.9 E-2
Chronic
2.0 E-l
USEPA, 2008
2.0 E-l
Chronic
1.0
NA
Aldrin
309-00-2
3.0 E-5
route-to-route
3.0 E-5
Chronic
3.0 E-5
USEPA, 2008
3.0 E-5
Chronic
1.0
0.04
alpha-BHC
319-84-6
NA
NA
NA
NA
1.0
0.04
Alpha-chlord ane
57-74-9
2.0 E-4
USEPA, 2008
2.0 E-4
Chronic
5.0 E-4
USEPA, 2008
5.0 E-4
Chronic
1.0
0.04
Anthracene
3.0 E-l
route-to-route
3.0 E-l
Chronic
3.0 E-l
USEPA, 2008
3.0 E-l
Chronic
1.0
0.13
Benzene
71-43-2
8.6 E-3
USEPA, 2008
8.6 E-3
Chronic
40 E-3
USEPA, 2008
40 E-3
Chronic
1.0
NA
Benzo (a) anthracene
Benzo (a) pyrene
56-55-3
50-32-8
NA
NA
NA
NA
NA
NA
NA
NA
1.0
1.0
0.13
0.13
Benzo (b & k) fluoranthene 1
205-99-2
NA
NA
NA
NA
1.0
0.13
Benzo (ghi) perylene
191-24^2
3.0 E-2
pyrene as surrogate
3.0 E-2
Chronic
3.0 E-2
pyrene as surrogate
3.0 E-2
Chronic
1.0
0.13
Benzo( a) anthracene
56-55-3
NA
NA
NA
NA
1.0
0.13
/ A V,
U.S. EPA REG ON X
Benzo(b)fluoranthene
205-99-2
NA
NA
NA
NA
Chronic
1.0
0.13
All toxicity values in units of mg/Kg-day
* - - - - - ^
1 s
AFRO.JFT GFNFRAI CORP
Benzo( k)fluoranthene
207-08-9
NA
NA
NA
NA
Chronic
1.0
0.13
Notes and Key:
bis(2-Ethylhexy l)phthal ate
117-81-7
2.0 E-2
route-to-route
2.0 E-2
Chronic
2.0 E-2
USEPA, 2008
2.0 E-2
Chronic
1.0
0.10
ABS = Dermal absorption efficiency
PRO^
SUPERFUND SITE
Bromodichloromethane
75-27-4
2.0 E-2
route-to-route
2.0 E-2
Chronic
2.0 E-2
USEPA, 2008
2.0 E-2
Chronic
1.0
NA
BIO = Bioavailability
Bromoform
2.0 E-2
route-to-route
2.0 E-2
Chronic
2.0 E-2
USEPA, 2008
2.0 E-2
Chronic
1.0
NA
mg/kg = Milligrams per kilogram
Carbon disulfide
75-15-0
2.0 E-l
USEPA, 2008
OEHHA, 2008
2.0 E-l
Chronic
1.0 E-l
USEPA, 2008
1.0 E-l
Chronic
1.0
NA
NA = Not applicable. Data is either not applicable for this chemical (e.g., not carcinogenic) or not available.
NCEA = National Center for Environmental Assessment (USEPA), as referenced in Multi-Region PRG Table (USE
Carbon tetrachloride
56-23-5
1.1 E-2
1.1 E-2
Chronic
7.0 E-4
USEPA, 2008
7.0 E-4
Chronic
1.0
NA
PA 2008b).
Chloroethane
75-00-3
2.9 E+0
USEPA 2008
2.9 E+0
Chronic
4.0 E-l
NCEA
40 E-l
Chronic
1.0
NA
PPRTV = Provisional Peer Reviewed Toxicity Values, National Center for Environmental Assessment (USEPA), as referenced in USEPA 2008b
Chloroform
67-66-3
1.3 E-2
PPRTV
1.3 E-2
Chronic
1.0 E-2
USEPA, 2008
1.0 E-2
Chronic
1.0
NA
(1) Only cadmium required the adjustment of the oral toxicity criteria for the dermal soil exposure pathway (USEPA 2004e).
Chrysene
218-01-9
NA
NA
NA
NA
Chronic
1.0
0.13
(2) Dermal absorption factors obtained from USEPA 2004e.
TABLE 2-4
(3) Total chromium is assessed using Cr(III) toxicity criteria.
(4) The provisional RfD is based upon TWA correction of occupational data for
application to non-occupational exposures.
Noncancer Toxicity Criteria
For the construction worker, the occupational data (with the TWA correction
removed) are utilized with the
Operable Unit 6 Record of Decision
application of the same uncertainty factors utilized to derive the provisional RfD.
Source: ERM, 2011
(5) All toxicity values in units of mg/Kg-day
ES042114142800SAC
-------
Inhalation
Oral(1)
Cancer
CAS
Weight of
Oral
Dermal
Chemical
Number
Value4
Reference
Value4
Reference
Evidence
BIO
ABS(2)
Aluminum
7429-90-5
NA
NA
D
1.0
NA
Antimony
7440-36-0
NA
NA
D
1.0
NA
Arsenic
7440-38-2
1.5 E+l
USEPA, 2008
9.45 E+0
OEHHA, 2008
A
0.6
0.03
Barium
7440-39-3
NA
NA
D
1.0
NA
Beryllium
7440-41-7
8.4 E+0
OEHHA, 2008
NA
B1
1.0
NA
Boron
NA
NA
1.0
NA
Cadmium
7440-43-9
1.5 E+l
OEHHA 2008
NA
B1
1.0
0.001
Chromium
16065-83-1
NA
NA
D
1.0
NA
Chromium VI
18540-29-9
5.1 E+2
OEHHA 2008
NA
A
1.0
NA
Cobalt
7440-48-4
9.8 E+0
PPRTV
NA
D
1.0
NA
Copper
7440-50-8
NA
NA
D
1.0
NA
Iron
7439-89-6
NA
NA
D
1.0
NA
Lead
7439-92-1
NA
NA
B2
0.44
NA
Lithium
7439-93-2
NA
NA
D
1.0
NA
Manganese
7439-96-5
NA
NA
D
1.0
NA
Mercury
7439-97-6
NA
NA
D
1.0
NA
Molybdenum
7439-98-7
NA
NA
D
1.0
NA
Nickel
7440-02-0
NA
NA
D
1.0
NA
Nitrate as N03
NA
NA
D
1.0
NA
Nitrate plus Nitrite (as N)
NA
NA
D
1.0
NA
Nitrite as N02
NA
NA
D
1.0
NA
Per chlorate
14797-73-0
NA
NA
D
1.0
NA
Selenium
7782-49-2
NA
NA
D
1.0
NA
Silver
7440-22-4
NA
NA
D
1.0
NA
Strontium
NA
NA
D
1.0
NA
Thallium
7446-18-6
NA
NA
D
1.0
NA
Titanium
7440-32-6
NA
NA
D
1.0
NA
Vanadium
7440-62-2
NA
NA
D
1.0
NA
Zinc
7440-66-6
NA
NA
D
1.0
NA
1,1,1-Trichloroethane
71-55-6
NA
NA
D
1.0
NA
1,1,2,2-Te tr ac hlo ro ethane
79-34-5
2.0 E-l
OEHHA 2008
2.7 E-l
OEHHA 2008
C
1.0
NA
1,1,2-Trichloroethane
79-00-5
5.7 E-2
OEHHA 2008
7.2 E-2
OEHHA 2008
C
1.0
NA
1,1-Dic hlor o ethane
75-34-3
5.7 E-3
OEHHA 2008
5.7 E-3
OEHHA 2008
C
1.0
NA
1,1-Dic hlor o ethe ne
75-35-4
NA
NA
D
1.0
NA
1,2,4-T rime thy lbe nze ne
95-63-6
NA
NA
D
1.0
NA
1,2-Dic hlorobenzene
NA
NA
D
1.0
NA
1,2-Dic hlor o ethane
107-06-2
9.1 E-2
USEPA 2008
9.1 E-2
USEPA 2008
B2
1.0
NA
1,2-Dic hloro ethe ne (c is/trans)
NA
NA
D
1.0
NA
1,3/5-T rim ethy lb enz ene
108-67-8
NA
NA
D
1.0
NA
1,3-Butadiene
106-99-0
6.0 E-l
OEHHA 2008
3.4 E+0
OEHHA 2008
B2
1.0
NA
1,4-Dichlor ob enze ne
2.2 E-2
NCEA
2.4 E-2
USEPA, 1997
1.0
NA
1,4-Dioxane
123-91-1
2.7 E-2
OEHHA 2008
2.7 E-2
OEHHA 2008
B2
1.0
0.1
2,2,4-T rim ethy lpentane
540-84-1
NA
NA
D
1.0
NA
2,3,7,8-TCDD TEQ
1746-01-6
1.5 E+5
USEPA, 1997
1.5 E+5
USEPA, 1997
1.0
0.03
2-Butanone (Methyl Ethyl Ketone)
78-93-3
NA
NA
D
1.0
NA
2-Hexanone
591-78-6
NA
NA
D
1.0
NA
2-Methylnaphthalene
NA
NA
NA
1.0
0.13
2-Propanol
67-63-0
NA
NA
D
1.0
NA
4,4-DDD
72-54-8
3.4 E-l
OEHHA, 2008
3.4 E-l
OEHHA, 2008
B2
1.0
0.03
4,4-DDE
72-55-9
3.4 E-l
OEHHA, 2008
3.4 E-l
OEHHA, 2008
B2
1.0
0.03
4,4-DDT
50-29-3
3.4 E-l
OEHHA, 2008
3.4 E-l
OEHHA, 2008
B2
1.0
0.03
4-Ethy lto lue ne
622-96-8
NA
NA
D
1.0
NA
4-Me thy 1- 2-pe ntano ne
108-10-1
NA
NA
D
1.0
NA
Acetone
67-64-1
NA
NA
D
1.0
NA
Acrolein
107-02-8
NA
NA
D
1.0
NA
Aldrin
309-00-2
1.7 E+l
OEHHA, 2008
1.7 E+l
OEHHA, 2008
B2
1.0
0.04
alpha-BHC
319-84-6
6.3 E+0
USEPA, 2008
6.3 E+0
USEPA, 2008
B2
1.0
0.04
Alpha-c hlo r da ne
57-74-9
1.2 E+0
OEHHA, 2008
1.3 E+0
OEHHA, 2008
B2
1.0
0.04
Anthracene
NA
NA
D
1.0
0.13
Benzene
71-43-2
1.0 E-l
OEHHA 2008
1.0 E-l
OEHHA 2008
A
1.0
NA
Benzo (a) anthracene
56-55-3
7.3 E-l
route-to-route
7.3 E-l
NCEA
B2
1.0
0.13
Benzo (a) pyrene
50-32-8
3.9 E+0
OEHHA, 2008
1.2 E+l
OEHHA, 2008
B2
1.0
0.13
Benzo (b & k) fluoranthene (total)
205-99-2
3.9 E-l
OEHHA, 2008
1.2 E+0
OEHHA, 2008
B2
1.0
0.13
Benzo (b) fluoranthene
205-99-2
3.9 E-l
OEHHA, 2008
1.2 E+0
OEHHA, 2008
B2
1.0
0.13
Benzo(a)pyrene
50-32-8
3.9 E+0
OEHHA 2008
1.2 E+l
OEHHA 2008
B2
1.0
0.13
Benzo(b&k)fluoranthene (total)
3.9 E-l
OEHHA 2008
1.2 E+0
OEHHA 2008
B2
1.0
0.13
Benzo(b)fluoranthene
205-99-2
3.9 E-l
OEHHA 2008
1.2 E+0
OEHHA 2008
B2
1.0
0.13
B enzo( ghi) per ylene
191-24-2
NA
NA
D
1.0
0.13
B enzo( k)fluor anthe ne
207-08-9
3.9 E-l
OEHHA 2008
1.2 E+0
OEHHA 2008
B2
1.0
0.13
bis(2-Ethylhexyl)phthalate
117-81-7
1.4 E-2
route-to-route
1.4 E-2
USEPA, 2008
B2
1.0
0.1
Bromodichlorome thane
75-27-4
1.3 E-l
OEHHA 2008
1.3 E-l
OEHHA 2008
B2
1.0
NA
Bromoform
3.9 E-3
USEPA, 2008
7.9 E-3
USEPA, 2008
B2
1.0
NA
Carbon Disulfide
75-15-0
NA
NA
D
1.0
NA
Carbon Tetrachloride
56-23-5
1.5 E-l
OEHHA 2008
1.5 E-l
OEHHA 2008
B2
1.0
NA
Chloro ethane
75-00-3
NA
NA
D
1.0
NA
Chloroform
67-66-3
8.1 E-2
USEPA 2008
3.1 E-2
OEHHA 2008
B2
1.0
NA
Inhalation
Oral*1'
Cancer
CAS
Weight of
Oral
Dermal
Chemical
Number
Value4
Reference
Value4
Reference
Evidence
BIO
ABS(2)
Chrysene
218-01-9
3.9 E-2
OEHHA 2008
1.2 E-l
OEHHA 2008
B2
1.0
0.13
c is-1,2-Dichlor oe the ne
60-57-1
NA
NA
D
1.0
NA
Cumene
98-82-8
NA
NA
D
1.0
NA
Cyclohexane
110-82-7
NA
NA
D
1.0
NA
delta-BHC
319-86-8
1.3 E+0
route-to-route
1.3 E+0
2008 Lindane as surrogate
1.0
0.04
Dibenz(a,h) anthracene
53-70-3
4.1 E+0
OEHHA 2008
7.3 E+0
OEHHA 2008
B2
1.0
0.13
Dibromoc hloro methane
124-48-1
9.4 E-2
OEHHA 2008
9.4 E-2
OEHHA 2008
C
1.0
NA
Die hloro difluorome thane
NA
NA
D
1.0
NA
Dieldrin
60-57-1
1.6 E+l
OEHHA, 2008
1.6 E+l
OEHHA, 2008
B2
1.0
0.04
Di-n-butyl phthalate
84-74-2
NA
NA
D
1.0
0.1
Endosulfan I
115-29-7
NA
NA
D
1.0
NA
Endosulfan II
115-29-7
NA
NA
D
1.0
0.1
Endrin
72-20-8
NA
NA
D
1.0
0.04
Ethanol
64-17-5
NA
NA
D
1.0
NA
EthylBenzene
8.7 E-3
OEHHA, 2008
1.1 E-2
OEHHA, 2008
D/B2
1.0
NA
Fluoranthene
206-44-0
NA
NA
D
1.0
0.13
Fluorene
NA
NA
D
1.0
0.13
Freon 11
75-69-4
NA
NA
D
1.0
NA
Freon 113
76-13-1
NA
NA
D
1.0
NA
Freon 12
75-71-8
NA
NA
D
1.0
NA
gamma-BHC (Lindane)
58-89-9
1.3 E+0
route-to-route
1.3 E+0
USEPA 1997b
B2
1.0
0.04
gamma-chlordane
57-74-9
1.2 E+0
OEHHA, 2008
1.3 E+0
OEHHA, 2008
B2
1.0
0.04
Heptachlor
76-44-8
4.6 E+0
USEPA, 2008
4.5 E+0
USEPA, 2008
B2
1.0
0.04
Heptachlor epoxide
1024-57-3
9.1 E+0
USEPA, 2008
9.1 E+0
USEPA, 2008
B2
1.0
0.04
Heptane
142-82-5
NA
NA
D
1.0
NA
Hex ac hlo r obutadie ne
7.8 E-2
USEPA, 2008
7.8 E-2
USEPA, 2008
C
1.0
NA
Hexane
110-54-3
NA
NA
D
1.0
NA
Hexanedioic Acid, dioctylester
103-23-1
1.2 E-3
route-to-route
1.2 E-3
C
1.0
0.1
Ind eno( 1,2,3- cd )py r e ne
193-39-5
3.9 E-l
OEHHA 2008
1.2 E+0
OEHHA 2008
B2
1.0
0.13
m,p-Xylene
1330-20-7
NA
NA
D
1.0
NA
Methyl tert-butyl ether
1634-04-4
9.1 E-4
OEHHA 2008
1.8 E-3
OEHHA 2008
1.0
NA
Methylene chloride
75-09-2
3.5 E-3
OEHHA 2008
1.4 E-2
OEHHA 2008
B2
1.0
NA
4-Methylphenol
106-44-5
NA
NA
C
1.0
0.1
m-Xylene
NA
NA
D
1.0
NA
Naphthalene
91-20-3
1.2 E-l
OEHHA 2008
NA
D
1.0
0.13
n-Butylbenzene
NA
NA
D
1.0
NA
N-Nitrosodimethylamine
62-75-9
4.9 E+l
USEPA, 2008
5.1 E+l
USEPA, 2008
B2
1.0
0.1
o-Xylene
95-47-6
NA
NA
D
1.0
NA
PCB-1248
12672-29-6
2.0 E+0
OEHHA 2008
5.0 E+0
OEHHA 2008
B2
1.0
0.14
PCB-1254
11097-69-1
2.0 E+0
OEHHA 2008
5.0 E+0
OEHHA 2008
B2
1.0
0.14
PCB-1260
11096-82-5
2.0 E+0
OEHHA, 2008
5.0 E+0
OEHHA, 2008
B2
1.0
0.14
Pendimethalin (Prowl)
40487-42-1
NA
NA
D
1.0
0.1
Pentachlorophenol
87-86-5
1.8 E-2
OEHHA 2008
1.2 E-l
USEPA, 2008
B2
1.0
0.1
Phenanthrene
85-01-8
NA
NA
D
1.0
0.13
Phenol
108-95-2
NA
NA
D
1.0
0.1
p-Iso propyl toluene
NA
NA
NA
1.0
NA
Propylbenzene
103-65-1
NA
NA
D
1.0
NA
p-Xylene
NA
NA
D
1.0
NA
Pyrene
129-00-0
NA
NA
D
1.0
0.13
se c-Butylbe nz ene
NA
NA
D
1.0
NA
Styrene
100-42-5
NA
NA
D
1.0
NA
Tetrachloroethene
127-18-4
2.1 E-2
OEHHA, 2008
5.4 E-l
OEHHA, 2008
B2
1.0
NA
Tetrahydrofuran
109-99-9
6.8 E-3
NCEA
7.6 E-3
NCEA
B2
1.0
NA
Toluene
108-88-3
NA
NA
D
1.0
NA
trans-1,2-Dic hlo r oe thene
156-60-5
NA
NA
D
1.0
NA
Trie hloro ethe ne
79-01-6
7.0 E-3
OEHHA, 2008
1.3 E-2
OEHHA, 2008
B2
1.0
NA
Trie hloro fluo ro methane
NA
NA
D
1.0
NA
Vinyl chloride
2.7 E-l
OEHHA, 2008
1.5 E+0
USEPA, 2008
A
1.0
NA
Xylenes (total)
1330-20-7
NA
NA
D
1.0
NA
Notes and Key:
NA = Not applicable. Data is either not applicable for this chemical (i.e., not carcinogenic) or not available.
Cancer weight of evidence classification:
A - human carcinogen
B1/B2 - probable human carcinogen
ABS = dermal absorption efficiency
BIO = bioavailability
mg/kg = Milligrams per kilogram
NCEA = National Center for Environmental Assessment (USEPA), as referenced in Multi-Region PRG Table (USEPA 2008b).
(1) No COPCs required oral toxicity criteria adjustment for the dermal soil exposure pathway (USEPA 2004e).
(2) Dermal absorption factors obtained from USEPA 2004e.
(3) Carcinogenic via inhalation only.
C - possible human carcinogen
D - not classifiable as to human carcinogenicity
Source: ERM, 2011
/W5\
* o \
V PBO"*1
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
TABLE 2-5
Carcinogenic Toxicity Criteria
Operable Unit 6 Record of Decision
ES042114142800SAC
-------
Table 2-6: Summary of Risks from Exposure to Surface Water by Exposure Area
Residential
Hazard Index
Lead Concentrations in
Surface Water (|a.g/L)
ILCR
Contaminant
of Concern
Exposure Area
Min
Max
Min
Max
Min
Max
Administration Area (East and West)
0.0000097
0.015
0.2
14
4E-08
3E-07
None
West Lakes, Line 2, Line 5 North Area
0.0006
0.015
0.49
140
8E-09
2E-06
BEHP
Chemical Plant 2
0.003
0.08
0.18
28
4E-07
2E-06
None
79
-------
Table 2-7: Summary of Risks from Exposure to Groundwater by Exposure Area
Vapor Intrusion
Domestic Use
Residential
Commercial
Hazard Index
ILCR
Hazard Index
Number of
ILCR
Number of
Hazard Index
Number of
ILCR
Number of
Exposure Area
Mill
Max
Primary Contributors
Mill
Max
Primary Contributors
Mill
Max
Locations
that Exceed 1
Mill
Max
Locations that
Exceed 1E-06
Mill
Max
Locations
that Exceed 1
Mill
Max
Locations that
Exceed 1E-06
Administration Area (East and West)
Perched (Layer Y)
1.5
4.700
VOCs. metals, perchlorate
6E-05
1E-01
VOCs. PAHs. PCBs. BEHP. NDMA
0.015
30
1 out of 8 locations
8E-06
1E-03
8 out of 9 locations
0.005
5
1 out of 8 locations
4E-07
3E-04
7 out of 9 locations
First Water Bearing Zone (Layer S)
0.45
770
VOCs. metals, perchlorate
1E-06
7E-02
VOCs. PAHs. BEHP. arsenic. NDMA
0.004
46
7 out of 18 locations
1E-07
3E-03
17 out of 20 locations
0.002
7
3 out of 18 locations
3E-08
8E-04
15 out of 20 locations
Layer C
0.2
2.100
VOCs. metals, perchlorate
5E-07
4E-03
VOCs. PCBs. BEHP. NDMA
Layer D
0.002
930
VOCs. metals, perchlorate
6E-07
2E-03
VOCs. BEHP. arsenic
Layer E
0.005
6
VOCs. metals
2E-05
2E-05
TCE
Layer F
0.002
0.004
None
NA
NA
NA
West Lakes, Line 2, Line 5 North Area
First Water Bearing Zone (Layer S)
1
740
PCE. TCE. perchlorate
9E-06
2E-03
VOCs. NDMA
0.0008
0.7
None
5E-07
1E-04
3 out of 4 samples
0.0003
0.1
None
1E-07
2E-05
2 out of 4 samples
Layer C
50
120
VOCs. perchlorate
2E-05
2E-05
Arsenic. VOCs
Layer D
0.4
16
Perchlorate. TCE
1E-06
4E-05
TCE. NDMA
Layer E
0.2
2
TCE
1E-06
7E-06
TCE
Layer F
0.3
0.6
None
5E-06
5E-06
TCE. NDMA
Chemical Plant 2
Perched (Layer Y)
0.015
100
VOCs. metals, perchlorate
1E-06
3E-04
VOCs
0.003
0.085
None
1E-07
2E-05
5 out of 8 samples
0.000009
0.01
None
3E-08
4E-06
1 out of 8 samples
First Water Bearing Zone (Layer S)
0.04
1.000
VOCs. metals, perchlorate
3E-05
2E-02
VOCs. BEHP. NDMA
0.005
4
1 out of 18 samples
9E-07
1E-04
14 out of 18 samples
0.0007
0.6
None
2E-07
3E-05
6 out of 18 samples
Layer A
3
120
VOCs. metals, perchlorate
8E-05
2E-03
VOCs. NDMA
Layer B
0.3
25
VOCs. metals, perchlorate
1E-06
1E-04
VOCs. arsenic, pesticides
Layer C
0.005
5.100
VOCs. metals, perchlorate
2E-07
2E-02
VOCs. BEHP. NDMA
Layer D
0.4
3.700
VOCs. metals, perchlorate
1E-06
1E-02
VOCs. NDMA
Layer E
2
2.200
VOCs. metals, perchlorate. acrolein
1E-05
3E-04
VOCs. BEHP
Note:
NC = no carcinogenic compounds of interest in a sample
81
-------
Table 2-8: Summary of Risks from Exposure to Soil and Sediment by Exposure Area
Residential
Construction Worker
Commercial/Industrial Worker
Recreational
Hazard Index
Primary
Contributors
Lead
Concentrations
in Soil
(ing/kg)
ILCR
Primary
Contributors
Hazard Index
Primary
Contributors
ILCR
Primary
Contributors
Hazard Index
Primary
Contributors
Lead
Concentrations
in Soil (mg/kg)
ILCR
Primary
Contributors
Hazard Index
Primary
Contributors
ILCR
Primary
Contributors
Exposure Area
Mill
Max
Mill
Max
Mill
Max
Mill
Max
Mill
Max
Mill
Max
Mill
Max
Mill
Max
Mill
Max
Mill
Max
Soil
Administration Area (East)
0.00005
42
PCBs and
iron
1.9
379
3E-10
2E-03
PCBs. PAHs.
VOCs
0.000013
11
PCBs and
iron
7E-11
7E-05
PCBs. PAHs
0.000004
4.4
PCBs
1.9
379
1E-10
7E-04
PCBs. PAHs.
VOCs
NA
NA
NA
NA
NA
NA
Administration Area
(West)
2E-07
4.3
Metals. PCBs
2
640
2E-10
4E-05
PCBs. PAHs.
VOCs. Cr6
4E-07
33
Metals. PCBs
3E-11
5E-04
Cadmium.
Cr6
0.0000002
0.3
None
2
640
8E-11
2E-05
PCBs. PAHs.
Cr6
NA
NA
NA
NA
NA
NA
Line 2
1E-07
1
Aluminum,
iron
NA
NA
1E-09
1E-05
PAHs
3E-07
3
Aluminum,
nickel
4E-11
4E-07
None
0.0000001
0.1
None
NA
NA
4E-10
4E-06
Benzo(b&k)-
fluoranthene
NA
NA
NA
NA
NA
NA
Line 5 North
0.00003
0.07
None
NA
NA
2E-10
5E-06
Benzo(a)pyrene
0.00007
0.02
None
2E-09
2E-07
None
0.00002
0.006
None
NA
NA
8E-11
1E-06
None
NA
NA
NA
NA
NA
NA
West Lakes
1E-07
0.03
None
NA
NA
1E-09
5E-07
None
2E-07
0.009
None
4E-11
1E-08
None
0.000001
0.004
None
NA
NA
3E-10
1E-07
None
NA
NA
NA
NA
NA
NA
Chemical Plant 2
1E-07
110
Metals.
PCBs.
pendimethalin
0.5
295
3E-10
1E-03
PAHs.
pesticides.
PCBs
2E-07
28
Metals.
PCBs.
pendimethalin
2E-11
4E-05
PCBs
0.00000009
11
PCBs.
pendimethalin
0.5
295
2E-10
4E-04
Benzo(a)pyrene.
PCBs
NA
NA
NA
NA
NA
NA
Magazine Area
3E-07
0.0000
7
None
NA
NA
2E-09
9E-09
None
7E-07
0.00002
None
7E-11
3E-10
None
0.000003
0.000007
None
NA
NA
7E-10
3E-09
None
NA
NA
NA
NA
NA
NA
Open Space Areas 1.2.3.
and 4
0.00002
0.0002
None
NA
NA
NC
NC
None
0.000045
0.000045
None
NC
NC
None
0.000015
0.000015
None
NA
NA
NC
NC
None
NA
NA
NA
NA
NA
NA
Open Space Areas 5 and 7
0.00001
0.0001
None
NA
NA
NC
NC
None
0.00003
0.00003
None
NC
NC
None
0.00001
0.00001
None
NA
NA
NC
NC
None
NA
NA
NA
NA
NA
NA
Sediment
Buffalo Creek
0.00004
1
None
5.6
72
3E-10
1E-05
PCB
0.00009
11
Manganese
8E-
12
4E-07
None
0.00003
0.11
None
5.6
72
6E-11
4E-06
PCBs
0.00000003
0.1
None
6E-06
2E-05
Arsenic. PCBs
Notes:
Shaded values exceed target levels. Refer to Tables 2-2, 2-3, and Appendix B for target levels.
Cr6 = hexavalent chromium
NA = not applicable
NC = no carcinogenic compounds of interest in a sample
83
-------
Table 2-9: Summary of Risks from Exposure to Soil Vapor by Exposure Area
Residential
Construction Worker
Commercial/Industrial Worker
Hazard Index
Number of
ILCR
Number of
Hazard Index
Number of
ILCR
Number of
Hazard Index
Number of
ILCR
Number of
Exposure Area
Mill
Max
Locations
that Exceed 1
Mill
Max
Locations that
Exceed 1E-06
Mill
Max
Locations
that Exceed 1
Mill
Max
Locations that
Exceed 1E-06
Mill
Max
Locations that
Exceed 1
Mill
Max
Locations that
Exceed 1E-06
Administration Area (East)
0.00011
860
25 out of 197 samples
NC
4E-02
84 out of 197 samples
0.0000005
3.4
1 out of 197 samples
NC
1E-05
1 out of 197 samples
0.000045
130
12 out of 197 samples
NC
1E-02
56 out of 197 samples
Administration Area (West)
0.000007
0.03
None
3E-09
5E-06
4 out of 81 samples
0.00000006
0.0001
None
2E-11
3E-08
None
0.000002
0.005
None
7E-10
1E-06
None
Line 2
0.000005
43
2 out of 126 samples
NC
6E-03
33 out of 126 samples
0.00000004
0.17
None
1E-10
2E-06
1 out of 126 samples
0.000002
6.7
2 out of 126 samples
NC
1E-03
15 out of 126 samples
Line 5 North
0.00003
0.06
None
6E-09
9E-06
2 out of 29 samples
0.0000003
0.0002
None
1E-12
2E-09
None
0.00001
0.01
None
1E-09
2E-06
1 out of 29 samples
Chemical Plant 2
0.000007
1.300
13 out of 104 samples
NC
4E-02
27 out of 104 samples
0.00000008
5
1 out of 104 samples
NC
9E-06
1 out of 104 samples
0.000003
200
9 out of 104 samples
NC
1E-02
18 out of 104 samples
Magazine Area
0.000005
0.05
None
NC
3E-06
1 out of 27 samples
0.00000006
0.0002
None
NC
7E-10
None
0.000002
0.008
None
NC
7E-07
None
Open Space Areas 1.2.3. and 4
0.006
0.01
None
7E-07
7E-07
None
0.00005
0.00005
None
2E-10
2E-10
None
0.002
0.002
None
2E-07
2E-07
None
Open Space Areas 5 and 7
0.007
0.02
None
6E-07
6E-07
None
0.00007
0.00007
None
2E-10
2E-10
None
0.002
0.002
None
1E-07
1E-07
None
Notes:
Shaded values exceed target levels.
NC = no carcinogenic compounds of interest in a sample
85
-------
2,7,4,2 Groundwater
There is no known current use of groundwater for residential water supply from unmonitored or
untreated wells either at or beyond the property boundary. However, recognizing the State's
designation of the aquifer as a potential drinking water source, the analysis included the
hypothetical use of untreated groundwater for residential water supply. This analysis considered
hypothetical exposure to groundwater constituents via the following routes: ingestion, dermal
contact, and inhalation of VOCs released during household non-ingestion use (i.e., showering,
cooking, laundering, and dishwashing). Although this ROD is not intended to address
groundwater contamination, groundwater contamination is present beneath the OU-6 area.
Because there is currently no sitewide land use covenant for groundwater, this ROD will
implement ICs similar to those adopted by OU-3 and OU-5 RODs, as well as ICs placed on the
Carveout Lands to restrict access and use of groundwater.
2, 7.4.3 Soil and Sediment
Potential soil exposure pathways may include the following:
Direct contact with soil (incidental ingestion and dermal contact)
Inhalation of fugitive dust
Volatilization of COPCs from soil and soil vapor into ambient (outdoor and indoor) air
Potential sediment exposure pathways may include the following:
Dermal contact with sediment during recreational (wading) activity
Incidental ingestion of sediment during recreational (wading) activity
Nine soil exposure areas were evaluated and one sediment exposure area (Buffalo Creek) was
evaluated. The 10 soil exposure areas include the following:
Administration Area East
Administration Area West
Line 2
Line 5 North
West Lakes
Chemical Plant 2
Magazine Area
OS Areas 1, 2, 3, and 4
OS Areas 5 and 7
The following subsections summarize the risk, hazard, and blood lead results for each of these
exposure areas by receptor.
Residential
Exposure to soil by future hypothetical residents at Administration Area East, Administration
Area West, and Chemical Plant 2 indicates His that are greater than the target level of 1 at
3 of the 10 soil exposure areas. Lead concentrations exceed the target level of 80 mg/kg at
87
-------
Administration Area East, Administration Area West, Line 2, Line 5 North, and Chemical
Plant 2. PCBs, metals, and pendimethalin are the primary contributors to HI where there are
exceedances. ILCRs are greater than the cumulative risk level of 1E-06 at six of the soil and
sediment exposure areas. These include Administration Area East, Administration Area West,
Line 2, Line 5 North, Chemical Plant 2, and Buffalo Creek. The primary contributors to the
ILCR at these sites include PCBs, PAHs, VOCs, hexavalent chromium, pesticides, and
2,3,7,8 -tetrachl orodib enzodi oxin (TCDD).
Construction Worker
Exposure to soil by construction workers at Administration Area East, Administration Area
West, Line 2, and Chemical Plant 2 indicates His that are greater than the target level of 1 at
six of the soil and sediment exposure areas. PCBs, metals, and pendimethalin are the primary
contributors to HI at the exposure areas where there are exceedances. ILCRs are greater than the
cumulative risk level of 1E-06 at three of the soil and sediment exposure areas. These include
Administration Area East, Administration Area West, and Chemical Plant 2. The primary
contributors to the ILCR at these sites include PCBs, PAHs, VOCs, cadmium, hexavalent
chromium, and TCDD.
Commercial/Industrial
Exposure to soil by commercial/industrial workers at Administration Area East and Chemical
Plant 2 indicates His that are greater than the target level of 1 at two of the soil and sediment
exposure areas. PCBs and pendimethalin are the primary contributors to HI at the exposure areas
where there are exceedances. Lead concentrations exceed the target level of 320 mg/kg at the
Administration Area East and Administration Area West. ILCRs are greater than the cumulative
risk level of 1E-06 at six of the soil and sediment exposure areas. These include: Administration
Area East, Administration Area West, Line 2, Chemical Plant 2, and Buffalo Creek. The primary
contributors to the ILCR at these sites include PCBs, PAHs, hexavalent chromium, and TCDD.
Soil vapor results were used to evaluate the vapor intrusion into indoor air pathway.
The following soil vapor exposure areas were evaluated:
Administration Area East
Administration Area West
Line 2
Line 5 North
Chemical Plant 2
Magazine Area
OS Areas 1, 2, 3, and 4
OS Areas 5 and 7
88
-------
The following subsections summarize the risk and hazard for each of these exposure areas by
receptor.
Residential
His are greater than the target level of 1 under a residential scenario at Administration Area East
(25 of 197 locations), Line 2 (2 of 126 locations), and Chemical Plant 2 (13 of 104 locations).
ILCRs are greater than the cumulative risk level of 1E-06 at seven of nine soil vapor exposure
areas. These include Administration Area East (84 of 197 locations), Administration Area West
(4 of 81 locations), Line 2 (33 of 126 locations), Line 5 North (2 of 29 locations), Chemical Plant
2 (27 of 104 locations), and Magazine Area (1 of 27 locations).
Construction Worker
His are greater than the target level of 1 under a construction worker scenario at Administration
Area East (1 of 197 locations) and Chemical Plant 2 (1 of 104 locations). ILCRs are greater than
the cumulative risk level of 1E-06 at three of the nine soil vapor exposure areas. These include
Administration Area East (1 of 197 locations), Line 2 (1 of 126 locations), and Chemical Plant 2
(1 of 104 locations).
Commercial Industrial/Worker
His are greater than the target level of 1 under a construction worker scenario at Administration
Area East (12 of 197 locations), Line 2 (2 of 126 locations) and Chemical Plant 2 (9 of
104 locations). ILCRs are greater than the cumulative risk level of 1E-06 at four of nine soil
vapor exposure areas. These include Administration Area East (56 of 197 locations), Line 2
(15 of 126 locations), Line 5 North (1 of 29 locations), and Chemical Plant 2 (18 of
104 locations).
2,7,5 Summary of Ecological Risk Assessment
The SLERA considered potentially exposed ecological receptors in each MA, including the
following terrestrial habitats: terrestrial plant and soil invertebrate communities; and bird
(including burrowing species), mammal (including burrowing mammals), and reptile and
amphibian populations and the following aquatic habitats: aquatic plant, invertebrate, and
sediment-dwelling invertebrate communities, and fish, amphibian, bird, and mammal
populations. Soil (collected between 0 and 6 feet bgs), soil vapor, sediment (generally collected
between 0 and 1.5 feet bgs), and surface water chemical data from the OU-6 RI were compared
to ecological screening levels (ESLs) developed for the SLERA and considered potential
ecological COCs if they exceeded these levels. Agency-recognized screening levels were used to
conservatively represent exposure concentrations that are protective of all receptors potentially
exposed to a given medium.
89
-------
The results of the SLERA for each of these MAs are summarized on Table 2-10. No/negligible
ecological risks were identified at five of the MAs, for the following reasons:
No contaminants of potential ecological concern (COPECs) exceeding ESLs were
identified in OS Areas 5 and 7; and
The COPECs and their exceedances of ESLs identified in habitat areas were considered
to be limited in magnitude, number, and areal extent at Magazine Area and OS Areas 1,
2, and 4.
For the remaining MAs, the following conclusions were reached:
For the Admin Area (Admin East and Admin West), no significant ecological risk within
the MA was identified under current or future land use due to the presence of poor-
quality habitat. However, COPECs were identified in drainage ditches leading from these
MAs with the potential for migration to downgradient habitats.
For the West Lakes MA, potential ecological risks under current conditions were
identified based on multiple COPECs occurring within habitat areas. However, these
areas may undergo residential development in the future, which is expected to mitigate or
eliminate ecological risk as a result of removing existing habitat.
For the remaining MAs (Buffalo Creek, Chemical Plant 2, and Dredge Pit and Eastern
Basin), potential ecological risks under current conditions were identified based on
multiple COPECs occurring within habitat areas; and future development is unplanned or
unknown.
2.7.6 C on c 1 ti s i o n s
Human health and ecological risk estimates are based on reasonable maximum exposure
scenarios and considered various conservative assumptions about frequency and duration of
exposure as well as the toxicity of the COPCs.
Areas potentially requiring cleanup were identified by calculating the human health and
ecological risks under the current and planned future land use, and by estimating the potential
risks from exposure to surface water, soil and sediment, and soil vapor contamination. Other
potential areas requiring a cleanup action were identified based on potential groundwater impacts
from contaminated soil. A detailed description of the modeling and procedures used to estimate
the risks can be found in the HHERA, which is in Volume 2 of the OU-6 RI/FS (ERM, 2011).
90
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Management
Area
Media
Evaluated
Habitat
COPECs
Habitat Quality Future Land Use Exposure Potential
Recommendation
Admin Area East
Soil
Surface Water
Soil Vapor
Phthalates
PCBs
Inorganics
Inorganics
Toluene
Poor
Poor
Poor
Commercial
Commercial
Commercial
Current - Moderate
Future - Moderate
Current - Low
Future - Low
Current - Low
Future - Low
SMDP: potential downgradient
migration (drainage ditch)
SMDP: potential downgradient
migration (drainage ditch)
No further action
Admin Area West
Soil
Surface Water
Soil Vapor
Phthalates
PCBs
Inorganics
Inorganics
None
Moderate
Poor
Poor
Commercial
Commercial
Commercial
Current - Moderate
Future - Moderate
Current - Low
Future - Low
Current - Low
Future - Low
SMDP: potential downgradient
migration (drainage ditch)
SMDP: potential downgradient
migration (drainage ditch)
No further action
Line 02
Soil
Soil Vapor
Phthalates
Inorganics
VOCs
Good Mixed Commercial/
Residential
Good Mixed Commercial/
Residential
Current - High
Future - Low
Current - High
Future - Low
No further action
No further action
Line 05 North
Soil
Soil Vapor
Cadmium
Di-n-octyl phthalate
None
Fair
(tailings)
Fair
(tailings)
Residential
Residential
Current - Medium
Future - Low
Current - Medium
Future - Low
SMDP to determine if further
action necessary
No further action
Westlakes
Soil
Surface Water
Sediment
PCBs
Inorganics
Phthalates
Inorganics
Inorganics
Fair
Fair
(intermittent)
Fair
(intermittent)
Residential,
Open/ Preserves,
Parks
Residential,
Open/ Preserves,
Parks
Residential,
Open/ Preserves,
Parks
Current - High
Future - Low
Current - High
Future - Low
Current - High
Future - Low
SMDP to determine if further
action necessary
SMDP to determine if further
action necessary
SMDP to determine if further
action necessary
Buffalo Creek
Soil
Surface Water
Sediment
PCBs
Inorganics
Pesticides
Inorganics
Pesticides
PCBs
Inorganics
Fair
Fair
(intermittent)
Fair
(intermittent)
Unknown
Unknown
Unknown
Current - High
Future - Medium
Current - High
Future - Medium
Current - High
Future - Medium
SMDP to determine if further
action necessary
SMDP to determine if further
action necessary
SMDP to determine if further
action necessary
Open Space Areas 5 and 7
Soil
Soil Vapor
None
None
Good
Good
Residential
Residential
Current - Medium
Future - Low
Current - Medium
Future - Low
No further action
No further action
Notes:
ESL
PCB
SMDP
VOC
= Ecological screening level
= Poly chlorinated biphenyl
= Scientific/Management Decision Point
= Volatile Organic Compound
Habitat COPECs = Chemicals above guild-specific ESLs and, for inorganics, above both ESLs and background concentrations in habitat areas;
does not include those constituents lacking screening levels
Management
Area
Media
Evaluated
Habitat
COPECs
Habitat Quality Future Land Use Exposure Potential
Recommendation
Chemical Plant2
Soil
Surface Water
Sediment
Soil Vapor
Phthalates
Pesticides
PCBs
Inorganics
Pesticides
Inorganics
Misc. Organics
PAHs
Pesticides
PCBs
Inorganics
None
Good
Fair
(intermittent)
Fair
(intermittent)
Good
Not currently
planned
Not currently
planned
Not currently
planned
Not currently
planned
Current - High
Future - High
Current - High
Future - High
Current - High
Future - High
Current - Low
Future - Low
SMDP to determine if further
action necessary
SMDP to determine if further
action necessary
SMDP to determine if further
action necessary
No further action
Dredge Pit andEastern Basin
Soil
Surface Water
Sediment
Phthalates
Pesticides
Inorganics
Pesticides
Inorganics
Misc. Organics
Pesticides
Inorganics
Good
Fair
(intermittent)
Fair
(intermittent)
Not currently
planned
Not currently
planned
Not currently
planned
Current - High
Future - High
Current - High
Future - High
Current - High
Future - High
SMDP to determine if further
action necessary
SMDP to determine if further
action necessary
SMDP to determine if further
action necessary
Magazine Area
Soil
Soil Vapor
Inorganics
None
Fair
Fair
Not currently
planned
Not currently
planned
Current - Low
Future - Low
Current - Low
Future - Low
No further action
No further action
Open Space Areas 1,2, and 4
Soil
Soil Vapor
Inorganics
Toluene
Fair
Fair
Not currently
planned
Not currently
planned
Current - Medium
Future - Medium
Current - Medium
Future - Medium
No further action
No further action
Area 39
Soil
Surface Water
Sediment
Soil Vapor
Phthalates
Fair
Dioxins (high human activity)
Furans
Inorganics
Inorganics
Inorganics
Good
Good
Not currently
planned
Not currently
planned
Not currently
planned
VOCs Fair Not currently
(high human activity) planned
Current - Medium
Future - Medium
Current - High
Future - High
Current - High
Future - High
Current - Medium
Future - Medium
SMDP to determine if further
action necessary
SMDP to determine if further
action necessary
SMDP to determine if further
action necessary
SMDP to determine if further
action necessary
* o \
uazy
PR 0"^
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
TABLE 2-10
SLERA Summary Table
Operable Unit 6 Record of Decision
ES042114142800SAC
-------
Risk management decisions may consider no further action, further investigation, and/or
implementing risk management action(s). These areas were then evaluated to determine if
cleanup was required. The following criteria, along with professional judgment, were used to
determine if a contaminated area (identified by the estimated risks) required cleanup:
If the potential human health risk was just above 1E-06, the HI was greater than 1.0, or
modeled blood lead concentration is greater than 1 |ig/dL from soil or sediment lead
concentration, then the area was recommended for cleanup evaluation.
If ecological risk exceeded screening levels, and the SLERA recommended further
evaluation for an action, then the area was recommended for cleanup.
If the risk of contaminating the groundwater was considered moderate (as defined in the
OU-6 FS), then the area may have been recommended for cleanup, depending on the
compound mobility and solubility, and depth and extent of contamination.
If the risk to groundwater was considered high (as defined in the OU-6 FS), the area was
recommended for cleanup.
If the risk to groundwater was based on the concentrations of TPH-D or TPH-Mo, then
the area was only recommended for retention if the concentrations were increasing, or if
TPH was encountered at depth and had already affected the groundwater.
2,7,7 Uncertainties
Some uncertainty is inherent in risk assessments. Uncertainty exists in the exposure assessment,
toxicity values, and the risk characterization. In the HHRA, exposure and the toxicity
assessments are the most significant sources of uncertainty and variability. The following
uncertainties could lead to overestimation of the risk of (1) modeling of contaminant uptake -
chemical concentrations were assumed to remain constant over the exposure period; (2) use of
the detected concentration of COPCs at each location as exposure point concentrations (EPC) -
EPCs assume that receptors are exposed to a single location through duration of their tenure at
the property as opposed to the more likely scenario of being exposed to an area averaged
concentration; (3) the use of upperbound values for ingestion, inhalation, and dermal contact rates;
and (4) the use of default values for exposure duration that are likely to overestimate exposures.
The following uncertainties could lead to over- or underestimation of the risk from the site:
1. The concentrations of the chemicals in the sample results may have been over- or
underestimated. The sampling locations were selected to identify the areas with the
greatest likelihood of containing chemicals of interest; therefore, the sampling and
analysis data are sufficient to characterize chemical concentrations and distributions and,
subsequently, the associated potential risks.
2. Toxicity information was not available for some of the elements or compounds detected,
so the toxicity data from elements or compounds with similar chemical structures were
used. Because the surrogates chosen are generally considered more toxic, the risk
estimates for these constituents are likely health protective.
93
-------
3. Dose-response information from animal studies was used to predict effects in humans.
Uncertainties related to differences in uptake, metabolism, and distribution of chemicals
in the body of test species and target species are addressed through use of conservative
assumptions (such as uncertainty factors) in establishing reference toxicity values, which
results in the likelihood that the risk is overstated.
2.8 Development and Selection of Remedial Action Areas
Several investigations within OU-6 have been conducted, and the findings were documented in
the OU-6 RI Report (ERM-West, 2010). The purpose of RI was to determine if activities within
OU-6, such as the development of propulsion systems and chemical manufacturing, resulted in
the discharge of chemicals into the environment at concentrations that pose, or could pose, an
unacceptable risk to human and ecological receptors or could impact beneficial use of
groundwater.
Because of the complex history of past operations and size of OU-6, source areas were identified
to focus the investigations on those areas with the potential for releases to the environment.
Source areas were identified as those areas where past industrial operations took place, and OUs
were assigned as part of the 2001 Stipulation and Order Modifying Partial Consent Decree
(EPA, 2002) and the Program Plan Modification Report (Aerojet, 2004). The source areas in
OU-6 are listed in Section 2.1, and a brief description of the source areas are in Table 2-11.
More details regarding the source areas are in the OU-6 RI Report (ERM-West, 2010). In
addition, significant portions of the facility were used as buffer zones between operating areas
and have no history of chemical use or disposal.
Soil and soil vapor samples were collected from the source areas in accordance with the
Field Sampling and Analysis Plan (Tetra Tech, 2006), and the analytical data were compared
to applicable screening levels based on risk to human health, ecological receptors, and for the
protection of groundwater. The results were subsequently documented in the RI Report,
Sections 4 through 6, for each of the seven MAs. Those areas - including individual sample
locations - with concentrations of contaminants greater than screening levels were then
further evaluated for potential risks to human and ecological health, and potential impacts to
groundwater. Generally, areas were evaluated in the FS for a remedial action that had an ILCR of
greater than lxlO"4, an HI greater than 1, posed a risk to groundwater quality, and/or posed a risk
to ecological receptors. In several areas where the ILCR was within EPA's risk management
range (an ILCR between lxlO"4 and lxlO"6), these areas were evaluated for alternatives because
there was some uncertainty in the characterization of the area, such as the lateral or vertical extent
were not defined or there was evidence to suggest the maximum concentrations of COCs had not
been identified. In these cases, a conservative approach was taken so that these areas were
evaluated and remedies were selected in order to address the uncertainties and mitigate the risks.
Based on the results of the risk evaluation, the areas with contamination that pose a potential risk
were assigned a remedial action area number, such as AE-R-1 and AE-SV-R-1, to track further
evaluation. Generally, the areas labeled with a MA identifier followed by "R-[number]" [e.g.,
AE-R-1] are areas with soil contamination; and areas labeled "SV-R-[number]" are areas with
soil vapor contamination. In addition to the areas identified using the methods described above,
seven soil vapor areas were identified based on the potential risk to ambient air from VOCs in
94
-------
groundwater. Groundwater contamination is present beneath a large portion of OU-6 and VOCs
migrating through the vadose zone into ambient air could pose a potential risk to human health.
To determine if the groundwater contamination could result in indoor air concentrations above
acceptable levels for unrestricted use, the DTSC version of the J&E model was used to determine
a vapor intrusion screening level for TCE. TCE was used in the model because it has the largest
lateral extent and is most frequently detected contaminant in groundwater. For an unrestricted use
scenario and target ILCR of lxlO"6, the J&E model predicts an exposure concentration of 11 |ig/L
for TCE in groundwater. Groundwater contamination is generally mapped or contoured using the
groundwater maximum contaminant level (MCL) concentration. The MCL for TCE in
groundwater is 5 (J,g/L, which results in an approximate ILCR of 5x 10"7 with an HQ of 0.15.
Using a conservative approach to account for variations in groundwater movement, different
groundwater contouring techniques, and variations in well spacing, any location where TCE was
present in groundwater at a concentration > 5 [j,g/L with an additional 100-foot buffer mapped
around that area was further evaluated in the FS for remedial alternatives. Seven areas were
identified and include AE-SV-R-3, AW-SV-R-1, L2-SV-R-1, L5-SV-R-3, MA-SV-R-1,
CP2-SV-R-6, and DPEB-SV-R-1. For more details on how these remedial action areas were
identified, please see Section 1.5.4 of the OU-6 FS.
These remedial action areas were then evaluated in the OU-6 FS (Shaw, 2012) for applicable
remedial alternatives that would best mitigate the risks associated with the remedial action area.
Tables 1-3 through 1-20 of the FS summarize the nature and extent of contamination and the risk
evaluation for each remedial action area.
The preferred remedy for each remedial action area was selected and presented in the Proposed
Plan. The source areas with corresponding soil remedial action areas are presented in Table 2-11.
The remedial action areas for soil vapor are not included in the table because the soil vapor areas
encompass several source areas. In many cases, these soil vapor remedial action areas are likely
the result of releases from multiple source areas, and/or the lateral extent of the contamination
encompasses multiple source areas. Soil and soil vapor remedial action areas are best represented
on Figures 2-23 through 2-31, and descriptions appearing in Appendix B. Because some of the
areas do not tie to known sources areas, they have been described in general/geographic terms
instead. It should be noted that the areas for each remedial action area shown on the figures have
been approximated, based on information gathered during the RI and the scale of figures. In most
areas, the lateral extent of contamination is sufficiently known such that remedial alternatives
can be evaluated and selected. However, further delineation of the extent of many of these areas
will be required to efficiently design and implement the remedy. Further delineation, will be
conducted during the remedial design phase.
95
-------
Table 2-11: Source Areas and Soil Remedial Action Areas
Management Area
Original Source Area
Designation
Description
Remedial Action
Area Designation3
Administration
Area
Administration
Area East
3D
Liquid rocket engine manufacturing - sumps in Building 20002 and 20004, former
5,000-gallon fuel oil tank southwest of Building 20002.
AE-R-1 to AE-R-9
4D
Area 20 surface water drainage system - ditch system south of Building 20004 and east of
Building 20024.
Source Area 4D also include septic tanks A20-ST05-1 and A20-ST05-2.
llDb
Area 20 surface water drainage system -
Former 5,000-gallon acid holding tank associated with Building 20022.
Septic tank A20-ST22.
50D
Boiler fuel oil storage - former 4,000-gallon underground fuel oil tank west of Building 20001.
Source Area 50D also includes septic tanks A20-ST01-1; A20-ST01-2; A20-ST01-3;
A20-ST01-4; and A20ST01-5.
51D
Former 3,000-gallon waste tank north of Building 20002.
-
Building 20034
X-ray facility.
-
RCRA Unit B
(20037 Container Storage)
RCRA Unit C
(20029 Treatment Unit)
The closure and monitoring of the RCRA units themselves (i.e., storage containers, storage
tanks, etc.) is conducted by DTSC. These RCRA units have been closed per DTSC
documentation.
RCRA Unit X
(20073 Storage Tanks)
Administration
Area West
5D
Area 20 surface water drainage system - ditch system and waste treatment ponds near
Building 20009.
AW-R-1 to AW-R-3,
AW-R-10 to AW-R-13
6D
Building 20009 drainage - abandoned pond.
AW-R-8, AW-R-9
8D
Sewage treatment - sewage treatment ponds.
-
9D
Area 20 surface water drainage system - ditch system south of Building 20009.
AW-R-10
12D
Area 20 surface water drainage system - ditch system west of Sites 8D and D(c).
AW-R-10
52D
Waste oil storage - former underground waste oil tank west of Building 20009.
AW-R-6
96
-------
Table 2-11: Source Areas and Soil Remedial Action Areas
Management Area
Original Source Area
Designation
Description
Remedial Action
Area Designation3
52D FWOT
Waste oil storage - former waste oil tank near Building 20009.
AW-R-7
52DTB
Waste oil storage - former waste oil tank near Building 20009.
AW-R-14
D(b)
Building 20009 surface water drainage system - ditch system west of Building 20009.
AW-R-4, AW-R-5,
AW-R-15
D(c)
Sewage treatment plant - treatment plant sludge drying area.
--
D(d)
Storm drain sump - sump west of Building 20025.
--
RCRA Unit W
(20018 Storage and
Treatment Tank)
RCRA Unit Y
(20025 Storage)
The closure and monitoring of the RCRA units themselves (i.e., storage containers, storage
tanks, etc.) is conducted by DTSC. These RCRA units have been closed per DTSC
documentation Any contamination in the environment as a result of releases from the units is
addressed under this ROD.
AW-R-16
Line 2 Region / Open Space 5
28E
Drum cleaning facility - wash slab and 2 gimite lined ponds 600 feet northwest of
Building 02028.
L2-R-4, L2-R-5,
L2-R-9
29E
Crawford Bomb Station - pond north of Building 02024.
Source Area 29E also includes septic tank L2-ST24.
L2-R-11
59E
Drum cleaning facility - low area approximately 500 feet west of Building 02028.
--
E(d)
Grind station - drainage area north of Building 02020.
Source Area E(d) also includes septic tank L2-ST20.
L2-R-2, L2-R-3,
L2-R-7, L2-R-8
E(e)
Grind station - dry well at Building 02020.
--
E(m)
Unknown operation - pond north of Buildings 02027, 02026, and 02025.
Source Area E(m) also includes septic tank L2-ST26 (and associated leachfield).
L2-R-10
E(n)
Office building - waste line east of Building 02025.
Source Area E(n) also include septic tank L2-ST25.
--
DSA
Drum storage area.
The DSA also includes septic tanks L2-ST28 and L2-ST90.
L2-R-6
97
-------
Table 2-11: Source Areas and Soil Remedial Action Areas
Management Area
Original Source Area
Designation
Description
Remedial Action
Area Designation3
RCRA Unit T
(02030 Tank Storage)
RCRA Unit Z
(20045 Storage Treatment
Tanks and Crystalizer)
The closure and monitoring of the RCRA units themselves (i.e., storage containers, storage
tanks, etc.) is conducted by DTSC. These RCRA units have closed per DTSC documentation.
NA
Line 2 drainage from Building 02023.
L2-R-1
Line 5 North / Open Space 7
5 IE, 52E, and E(l)
Laboratory - concrete wash sump, low areas, septic tank (Building 05087).
L5-R-3, L5-R-4,
L5-R-5
NA
Line 5 solid rocket test stand associated with Building 05112.
L5-R-2
NA
Line 5 drainage from Buildings 05089 and 05099 to Buffalo Creek.
L5-R-1
Buffalo Creek
NA
Buffalo Creek transects the Aerojet Superfimd Site and receives stormwater from many
source areas in Area 00, Line 1, Line 2, Line 6, and Zone 3.
BC-R-1, BC-R-2
West Lakes / Open Space 6
NA
The West Lakes receives stormwater runoff from various areas of the Aerojet facility via the
Main Administration Area ditch and Buffalo Creek.
WL-R-1
Magazine Area / Open Space 3
NA
The Magazine Area consists of storage bunkers, shipping and transfer facilities, and safety
shelters.
MA-R-1
RCRA Unit C
(Building 48008
Container Storage)
The closure and monitoring of the RCRA units themselves (i.e., storage containers, storage
tanks, etc.) is conducted by DTSC. These RCRA units have closed per DTSC documentation.
~
Chemical Plant 2 /
Open Spaces 1,2, and 4
59F
Chemical manufacturing - lined holding basin, sumps, steel tank, low area (unlined pond) and
septic tank.
CP2-R-1 to CP2-R-6
CP2-R-10, CP2-R-11,
CP2-R-12
60F
Wastewater from Buildings 15001 and 15003 - Septic tank CP2-ST01/03.
--
61F
Drum storage area - concrete sump associated with Building 15001N.
--
62F
Chemical storage - Stainless steel paraldehyde tank.
--
CP2-07
Suspect area near Building 15007 - area of soil discoloration discovered during Stage 1 RI.
--
CP2-08
Chemical storage - drum storage (potentially pump oil containing PCBs).
CP2-R-9
98
-------
Table 2-11: Source Areas and Soil Remedial Action Areas
Management Area
Original Source Area
Designation
Description
Remedial Action
Area Designation3
F(c)
Sump - boiler blowdown sump.
CP2-R-8
RCRA Unit E
(1500 IN, 15005 Container
Storage)
The closure and monitoring of the RCRA units themselves (i.e., storage containers, storage
tanks, etc.) is conducted by DTSC. These RCRA units have been closed per DTSC
documentation.
RCRA Unit I
(700 Area Storage and
Treatment Tanks)
25F
Dredge pit and eastern basin - chemical waste disposal pit - unlined dredge pit and eastern
drainage basin.
Source Area 25F also include septic tanks A48-ST13 and A48-ST19.
DPEB-R-1
NA
Low area - drainage for northern portion of Chemical Plant 2.
CP2-R-7
Notes:
a This table presents only the remedial action areas for soil. The remedial action areas for soil vapor are not included in the table because the soil vapor areas are likely the result
of releases from multiple source areas, In addition, the lateral extent of the soil vapor remedial action areas overlap and encompass multiple source areas.
b The cleanup of 1 ID drainage ditch (Area 20) was previously completed under OU-5.
= no remedial action areas for soil were identified in these source areas. These sources were evaluated but determined to be of no concern.
NA = not applicable; remedial action area is not associated with a specific source area
99
-------
Soil Sample Locations
Soil Vapor Sample Locations
Legend
Selected Alternative for Retained
Remedial Areas:
Alternative 3 (Engineering Controls)
Alternative 3 (Capping)
Alternative 4 (Excavation)
Alternative 4 (SVE)
Road
Structure
Management Area/Open Space Boundary
Soil Boring Location
A Soil Vapor Location
Note:
Additional details regarding the soil or soil vapor
sample locations are in the Boundary OU Rl
(ERM, 2010).
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
Figure 2-23
Remedial Action Areas for
Administration Area East
Operable Unit 6
Record of Decision
US Hwv
Administration
Area East
Remedial Action Areas
for Soil
Remedial Action Areas
for Soil Vapor
\\YOSEMITE\Proj\USEPA\385248Aerojet\GIS\Maps\Fig2_23.mxd
ES042114142800SAC
-------
Administration
Area West
Remedial Action Areas
for Soil^
Soil Sample Locations
Soil Vapor Sample Locations
: l_
Legend
Selected Alternative for Retained
Remedial Areas:
Alternative 3 (Engineering Controls)
Alternative 3 (Capping)
Alternative 4 (Excavation)
Alternative 4 (SVE)
Road
Structure
Management Area/Open Space Boundary
Soil Boring Location
A Soil Vapor Location
Note:
Additional details regarding the soil or soil vapor
sample locations are in the Boundary OU Rl
(ERM, 2010).
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
Figure 2-24
Remedial Action Areas for
Administration Area West
Operable Unit 6
Record of Decision \t PR01t/
0 180 360
Remedial Action Areas
for Soil Vapor
\\YOSEMITE\Proj\USEPA\385248Aerojet\GIS\Maps\Fig2_24.mxd
ES042114142800SAC
-------
Aerojet
Legend
Selected Alternative for Retained
Remedial Areas:
Alternative 3 (Engineering Controls)
Alternative 3 (Capping)
Alternative 4 (Excavation)
Remedial Action Areas
for Soil-...
Alternative 4 (SVE)
Alternative 4 (Excavation with Soil
Flushing and Air Stripping)
Soil Sample Locations
Structure
Management Area/Open Space Boundary
Soil Boring Location
A Soil Vapor Location
Buffalo Creek
Note: Additional details regarding the soil or soil vapor
sample locations are in the Boundary OU Rl (ERM, 2010)
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
Figure 2-25
Remedial Action Areas for
Line 2 Region
Operable Unit 6
Record of Decision
Remedial Action Areas
for Soil Vapor
<,
-------
US Hw
Line 5 North
os-r Aerojet
Line 5 North
Legend
Selected Alternative for Retained
Remedial Areas:
Alternative 3 (Capping)
Alternative 4 (Excavation)
Remedial Action Areas
for Soil
Soil Sample Locations
Alternative 4 (SVE)
Structure
Soil Boring Location
A Soil Vapor Location
Note:
Additional details regarding the soil or soil vapor
sample locations are in the Boundary OU Rl
(ERM, 2010).
L5-SV-R-1
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
L5-SV-R-3
L5-SV-R-2
Figure 2-26
Remedial Action Areas for
Line 5 North
Operable Unit 6
Record of Decision
Remedial Action Areas
for Soil Vapor s/'Y*.
Soil Vapor Sample Locations
'==* i ^
PRO"*1
\\YOSEMITE\Proj\USEPA\385248Aerojet\GIS\Maps\Fig2_26.mxd
ES042114142800SAC
-------
US Hw
-Westlakes OS-6
Aerojet
WL-R-1
Legend
Selected Alternative for Retained
Remedial Areas:
Alternative 3 (Capping)
Alternative 4 (Excavation)
Remedial Action Areas
! for Soil
Alternative 4 (SVE)
Soil Sample Locations
Structure
Soil Boring Location
A Soil Vapor Location
Note:
Additional details regarding the soil or soil vapor
sample locations are in the Boundary OU Rl
(ERM, 2010).
* No soil vapor samples were collected from the
Westlakes area or Buffalo Creek.
r- 1 c-==ฐ
,i Remedial Action Areas
for Soil Vapor*
Soil Vapor Sample Locations
K ฆฆhdx.P-.^ ^
'"J PKOl6-
\\YOSEMITE\Proj\USEPA\385248Aerojet\GIS\Maps\Fig2_27.mxd
ES042114142800SAC
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Management Area/Open Space Boundary
Soil Boring Location
Soil Vapor Location
Additional details regarding the soil or soil vapor
sample locations are in the Boundary OU Rl
(ERM, 2010).
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
Figure 2-29
Remedial Action Areas for
Chemical Plant 2 and OS-1.^%
Operable Unit 6 J f
Record of Decision \ PK01t/
\\YOSEMITE\Proj\USEPA\385248Aerojet\GIS\Maps\Fig2_28.mxd
ES042114142800SAC
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(Dredge Pits
Aerojet
DPEB-R-1
Legend
Selected Alternative for Retained
Remedial Areas:
Alternative 2 (Institutional Controls)
Alternative 3 (Capping)
Alternative 4 (Excavation)
Remedial Action Areas
for Soil
Soil Sample Locations
Alternative 4 (SVE)
Structure
Management Area/Open Space Boundary
DPEB-SV-R-1
Soil Boring Location
A Soil Vapor Location
Note:
Additional details regarding the soil or soil vapor
sample locations are in the Boundary OU Rl
(ERM, 2010).
U.S. EPA REGION IX
AEROJET GENERAL CORP.
SUPERFUND SITE
Figure 2-30
Remedial Action Areas for
Dredge Pit, Eastern Basin
and OS-2 yjj
Operable Unit 6 ง
Record of Decision
x x x i
l|
Soil Vapor Sample Locations
Remedial Action Areas
for Soil Vapor
\\YOSEMITE\Proj\USEPA\385248Aerojet\GIS\Maps\Fig2_30.mxd
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2.9 Remedial Action Objectives
The remedial action objectives (RAOs) describe what the selected remediation effort is expected
to accomplish. The following RAOs have been identified for OU-6:
Prevent present and future worker and resident exposure to COCs in soils within the
upper 12 feet and ecological receptors within the upper 6 feet that pose an unacceptable
risk for areas identified in Table 2-11.
Prevent migration of COCs in soil and soil vapor to groundwater for areas identified in
Table 2-11 that could impair beneficial uses and to be consistent with current and future
sitewide groundwater remedies.
Prevent exposure to VOCs in ambient air at levels exceeding the health-based ambient air
screening levels for the current and planned future land use.
For contaminated soil and soil vapor, the RAOs are based on site-specific potential
exposure information as used in the HHRA and ERA and on current values for the
hazards posed by the COCs. The soil and soil vapor cleanup levels (Tables 2-2 and 2-3)
are calculated to reduce human health and ecological risks to protective levels for
unrestricted future land use.
There may still be some uncertainty in the characterization of the contamination within OU-6
in some areas, such as the lateral or vertical extent not being fully defined or the maximum
concentrations of COCs not having been identified. To ensure that all contamination is addressed
at each remedial action area, during remedial design additional data will be collected and all
COCs identified for each area will be screened against all three cleanup levels (protection of
human health, ecological receptors, and groundwater), where applicable, regardless of the
pathway that is triggering the action. For example, if TCE was identified as COC for the
protection of groundwater, during the remedial design, TCE concentrations would be compared
to cleanup levels for human health and ecological receptors, in addition to the cleanup levels for
the protection of groundwater. This will help eliminate any unexpected exposures and ensure that
the remedy for the remedial action area meets all cleanups levels prior to completing the
remedial action and closing the site.
Furthermore, if additional characterization demonstrates that there is no remaining risk to any
receptor above acceptable levels, and the RAOs have been met, the remedial action areas can be
evaluated for closure.
2.10 Description atives
The RI, along with the human and ecological risk evaluations, identified areas that required action
to prevent exposure. The FS assessed a range of possible actions needed to prevent unacceptable
human and ecological exposure. Representative process options were screened and assembled
into the following four remedial alternatives that address a broad range of site conditions and
contaminant types:
Alternative 1 - No Action
Alternative 2 - ICs
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Alternative 3 - Containment and Engineering Controls, incorporating Alternative 2 ICs
Alternative 4 - Source Removal/Reduction
EPA is required by law to consider a No Action Alternative and to evaluate viable cleanup or
containment alternatives against nine criteria. The OU-6 remedial alternatives were compared
against all of the nine regulatory evaluation criteria found in the National Contingency Plan,
40 CFR ง 300.430(e)(9), including community acceptance, which was solicited during the public
comment period. For an alternative to be considered as a possible final remedy, it must meet
EPA's two threshold criteria, which are (1) to protect human health and the environment and
(2) to comply with specific State and federal regulations known as applicable or relevant and
appropriate requirements (ARARs). Appendix B presents a summary of the remedial actions
along with the selected remedies and rationale for the actions.
2.10.1 Alternative I No Action
No engineered measures, ICs, or monitoring would be implemented in OU-6 to reduce source
area concentrations, prevent chemical migration, restrict or eliminate potential exposures to site
chemicals, or reduce exposure of chemical concentrations to potential human or ecological
receptors. The No Action Alternative is required by the NCP to provide a baseline for evaluation/
comparison of the costs and benefits of other alternatives. The No Action Alternative for OU-6 is
not a viable remedy alternative because it does not meet either of EPA's threshold criteria.
2.10.2 Alternative 2 Institutional Controls
Alternative 2 consists of ICs for all areas where the risk to human health is the result of vapor
intrusion and to prevent unacceptable exposures to contamination remaining onsite. EPA
considers ICs to include "non-engineered instruments, such as administrative and legal controls,
that help to minimize the potential for human exposure to contamination and/or protect the
integrity of the response action". ICs typically are designed to work by limiting land or resource
use or by providing information that helps modify or guide human behavior at a site. Some
common examples of ICs include zoning restrictions, building or excavation permits, well
drilling prohibitions, easements, and covenants. At sites where contamination is left in place such
that unrestricted land use and unlimited exposure would not be warranted, ICs should be
considered to ensure that unacceptable exposure from residual soil, or soil vapor containing
COCs does not occur.
This ROD addresses soil and soil vapor contaminated areas. Although this ROD is not intended
to address groundwater contamination, groundwater contamination is present beneath the OU-6
area. Because there is currently no sitewide land use covenant for groundwater, this ROD will
implement ICs similar to those adopted by OU-3 and OU-5 RODs, as well as ICs placed on the
Carveout Lands to restrict access and use of groundwater.
The objectives of ICs that may be applied to OU-6 include the following:
Notice and, as appropriate, restrictions on residential land use (through management
controls or use restrictions) where residual COCs would remain in place at concentrations
that are above the levels that would allow for unrestricted use;
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Notice, and as appropriate, restrictions on commercial/industrial land use (through
management controls or use restrictions) in areas where existing chemical concentrations
exceed risk-based levels for commercial/industrial uses;
Notice and, as appropriate, requirements for appropriate health and safety and materials
management procedures for excavations in areas of residual COCs.
The mechanisms that may be used for implementation of ICs for OU-6 may include
governmental controls, proprietary controls, and information devices.
Governmental controls involve obligations under which a government has direct enforcement
rights. Governmental controls that could be applied to OU-6 include the following:
Land use restrictions imposed by the local agencies (e.g., zoning restrictions) that specify
and control allowable land uses and restrict residential uses to areas meeting standards for
unrestricted use;
Building permit notifications and restrictions; and
Restrictions on development as contained in environmental deed restrictions or covenants
running with the land that are enforceable by one or more state agencies.
Proprietary controls include environmental covenants or environmental easements that are
recorded against a particular piece of property and run with the land. For OU-6, an
environmental covenant will need to be developed to meet each of the IC objectives. The
covenants and environmental restrictions would restrict future use of contaminated soil and
groundwater areas that have not attained residential cleanup objectives, whereby Aerojet would
covenant to impose these restrictions. These covenants and environmental restrictions will be
binding to Aerojet's successors and assigns as covenants running with the land. EPA and
Cal-EPA will have the right to enforce these restrictions. Aerojet would be required to give
written notice of the soil, soil vapor, or groundwater contamination to each buyer, lessee, renter
and mortgagee of any of these lands and every lease, deed, mortgage or instrument conveying
any part of these lands shall expressly provide that it is subject to this declaration of covenants
and environmental restrictions.
Both Sacramento County and City of Rancho Cordova have restrictions that require permits and
evaluations for any wells that are within 2,000 feet of any known groundwater contaminant
plume. This special "consultation zone policy" review by appropriate regulatory agencies
(including, but not limited to, Sacramento County Environmental Management Department and
RWQCB) are detailed in Sacramento County Code Number 1455, Section 6.28.000 and Rancho
Cordova Municipal Code 6.28.000 - Wells and Pumps.
In addition to environmental covenants, environmental easements could be recorded over areas
subject to restricted uses. The environmental easements could be developed and granted to the
state or local agencies to ensure adherence to environmental covenants and governmental
controls, and to provide the agencies with a mechanism for legal enforcement of the covenants
and controls against future property owners. In this respect, the easement/covenant has a
"governmental" control aspect that would not be present if the easement were entirely between
landowners.
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Information devices may also be part of the ICs to be used for OU-6 and the site as a whole.
These could include deed notices identifying presence of COCs, land use restrictions, and
requirements for land use (which were included in the deed restrictions for the Carve-Out
Lands). Information devices also consist of inclusion of the site on the state registries of
hazardous waste/contaminated sites. In this regard, the site is currently listed in the Geo-Tracker
database and geographic information system (GIS) of environmental data. Geo-Tracker was
developed by the State Water Resources Control Board pursuant to a mandate by the California
State Legislature. Geo-Tracker tracks various sites, including Spills-Leaks-Investigations-Cleanups
sites such as the Aerojet Superfund Site. Currently, the site is also listed in the DTSC EnviroStor
Data Management System (database) and GIS registry of hazardous waste sites and sites that
have known COCs. In addition, DTSC is required to maintain on the internet a list of all land use
restrictions recorded under its statutes. DTSC maintains a contract with Terradex which notifies
DTSC when risky activities occur above contaminated sites which contain these recorded
restrictions.
At the local level, the presence of COCs and restrictions on land uses and groundwater use at the
Aerojet Superfund Site are identified in various planning documents prepared by Sacramento
County and municipalities in the area of the site.
2J ft 2! Soil ICs
With respect to future use of contaminated soil areas that have not attained residential cleanup
objectives, EPA, DTSC and the RWQCB would seek LUCs, such as a declaration of covenants
and environmental restrictions to be recorded by Aerojet that would be binding on Aerojet's
successors and any new buyer, lessee, renter, mortgagee of any of these soil areas. A declaration
of covenants and environmental restrictions would restrict use in such areas. In addition, if there
is a constructed cap or SVE system, protections of these systems may be included in the LUCs.
Also, in some of the OU-6 MAs, residual COCs are present beneath existing buildings, utility
corridors, landscaped areas, and other infrastructure features at levels that could potentially pose
a health risk under residential or, in some cases, to commercial/industrial uses. Soils remaining
in place at levels greater than the planned use, including soils at depth, will be managed under ICs
and/or engineering controls until such time as the overlying feature is removed and the
contaminated material can be remediated.
The presence of these buildings and infrastructure features present physical limitations to the
implementation and/or potential effectiveness of various engineered controls that might
otherwise be applicable for removing or reducing the COCs. For example, the presence of a large
office or warehouse building overlying residual non-VOC COCs in shallow, unsaturated soil
would prevent, or at a minimum greatly restrict, the applicability of active engineered measures
such as soil excavation and disposal or soil treatment. Consequently, the available remedial
technologies are unlikely to remove or reduce COCs beneath these buildings to levels that would
allow for unrestricted use. Therefore, ICs would be appropriate to prevent exposure and ensure
remedial action is taken when the building is removed. In addition, ICs will be implemented to
assure protectiveness throughout OU-6.
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2 ! ft 2.2 Soil Vapor ICs
Large portions of OU-6 have underlying groundwater containing COCs. VOCs in groundwater
can be a source of VOCs in the vadose zone with a potential to migrate into overlying buildings
(vapor intrusion). In addition, releases of VOC contaminants from source areas in OU-6 may also
result in VOC migration from the subsurface into overlying buildings. The HHERA evaluated
risks posed by the VOC migration. In areas that the HHERA indicated a potential significant risk
from vapor intrusion from COCs, and the COCs are unlikely to be remedied in the near future to
levels below that risk level, ICs would be warranted to restrict property use or would be used in
conjunction with containment or engineering controls (e.g., vapor barriers) that would allow for
restricted use.
ICs for soil vapor intrusion could include:
Notice of the existing conditions known to the environmental agency that may cause
potential unacceptable risks from vapor intrusion or underlying groundwater;
Prohibition against specific uses of the property without authorization;
Prohibition against activities that may interfere with the integrity or performance of vapor
intrusion mitigation or groundwater remediation systems;
Right of access to the property for agencies to inspect, monitor, and perform other
activities relative to such systems;
Right of access to the property for the person responsible for implementing the O&M
activities relative to such systems; and
Inspection and reporting requirements for the owner of the property.
Appropriate monitoring and land use covenants are required for either residential or commercial
use of OU-6 locations until the potential threat of vapor intrusion is removed.
2.10.2.3 Groundwater ICs
As stated before, although this ROD is not intended to address groundwater contamination,
groundwater contamination is present beneath the OU-6 area. Because there is currently no
sitewide land use covenant for groundwater, this ROD will implement ICs similar to those
adopted by OU-3 and OU-5 RODs, as well as ICs placed on the Carveout Lands to restrict access
to groundwater. As stated in the OU-5 Interim ROD for Groundwater, "These [institutional]
controls will include Sacramento County review of new well drilling permits and prohibitions on
access to groundwater on the land overlaying the contaminated groundwater to restrict use of
untreated groundwater within the contaminated portions of the aquifer until the final water
quality objectives have been attained." (See Appendix A for the groundwater plume locations.)
In addition, the OU-6 ROD will require ICs enforceable through State land use controls
whenever any portion of Aerojet-owned property above a groundwater contaminant plume is
transferred. These restrictions will be implemented through a recorded covenant pursuant to
22 California Code of Regulations (CCR) Section 67391.1(a), (d) and other applicable California
law, whereby Aerojet covenants to impose these restrictions. These land use covenants will be
binding on Aerojet's successors and assigns as covenants running with the land. The State of
California and EPA (as a third-party beneficiary) will have the right to enforce these restrictions.
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Any lease or sale of Aerojet property overlying the contaminated groundwater in OU-6 shall be
subject to the following restrictions:
No recharge of groundwater unless and until expressly permitted in writing by EPA and
the RWQCB;
No injection into the groundwater unless approved in writing by EPA and the RWQCB;
No sustained extraction of groundwater encountered during construction without written
approval by EPA and the RWQCB.
Aerojet shall give written notice of the groundwater contamination to each buyer, lessee,
renter, and mortgagee of any of these lands; and every lease, deed, mortgage, or instrument
conveying any part of these lands shall expressly provide that it is subject to this Declaration of
Covenants and Environmental Restrictions.
In addition to the groundwater ICs already in place, other restrictions already applied to the
OU-6 area include the Sacramento Consultation Zone policy, the PCD identifying areas subject
to excavation restrictions, and Aerojet's Soil Excavation or Grading, or Construction Debris
Movement Notification Requirements for Soil Excavation and Grading Requirements.
2.10.3 Alternative 3 Containment and Engineering Controls, incorporating
Alternative 2 ICs
The third alternative consists of construction of new containment systems, maintenance of
existing barriers to COC exposure, and development and implementation of engineering controls
to reduce or prevent exposure to existing and future building occupants that may be subject to
vapor intrusion or exposed to contaminants in soils. Engineering controls encompass a variety of
engineered and constructed physical barriers (e.g. soil capping, sub-surface venting systems,
mitigation barriers, fences) to contain and/or prevent exposure to contamination on a property.
Examples of containment and engineering control technologies that may be implemented for
OU-6 include the following:
Placement of capping materials (pavement, gravel layer, etc.) over areas with chemicals
posing potential risks above commercial/industrial levels;
Placement of backfill materials (clean soil, etc.) over areas with chemicals posing
potential risks above human and ecological levels;
Monitoring the presence and thickness and maintenance of new and existing capping
materials (e.g., buildings, foundations, roadways, and parking lots) that currently overlie
areas of COCs within OU-6 to ensure the integrity of the capping materials;
Modification and monitoring of the HVAC systems of existing buildings to ensure
sufficient air exchange rates to limit vapor intrusion and reduce indoor air concentrations
to safe levels based on the Johnson and Ettinger Model (1991) or an alternative industry-
accepted standard calculations;
Construction and operation of foundation venting systems around and/or beneath existing
buildings, and adoption of engineering or management controls requiring vapor mitigation
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to reduce or prevent VOC intrusion into buildings through the installation of SSV and/or
SSD systems or alternative system designed to prevent intrusion of contaminants to indoor
air;
Construction and operation of foundation venting systems around and/or beneath new
construction and adoption of engineering or management controls requiring vapor
mitigation to reduce or prevent VOC intrusion into buildings through the installation of
vapor barriers (synthetic membrane) SSDs, SSVs, or alternative systems designed to
prevent intrusion of contaminants to indoor air.
Alternative 2 ICs, as described in Section 2.10.2, are incorporated as part of Alternative 3 and
would also be implemented as part of this alternative to protect the integrity of the cap and vapor
intrusion mitigation systems, to identify the presence of engineering controls in place, and for
long-term protection and maintenance requirements. These long-term requirements refer to the
activities necessary to ensure that engineering controls are maintained and that ICs continue to be
enforced. If additional characterization demonstrates that there is no remaining risk from soil
contaminants in the vadose zone to any receptors above acceptable levels, then ICs under
Section 2.10.3 would continue to apply only where groundwater contaminants continue to pose
a risk.
2.10.4 Alternative 4 Source Removal/Redtictlon
This alternative would include actions taken to remove either source materials or environmental
COCs so as to reduce COC concentrations to allow for unrestricted use or to levels that would
allow for restricted uses. Examples of source removal/reduction actions that would be taken as
part of this alternative include the following:
Excavation and offsite disposal of soil containing site-related chemicals at concentrations
above levels for unrestricted use;
Excavation of soil containing VOCs at concentrations that present an unacceptable risk
from soil vapor migration into indoor air under an unrestricted use scenario or present a
threat to groundwater quality; and
SVE for VOCs in soil vapor at concentrations that present an unacceptable risk from soil
vapor migration into indoor air under an unrestricted use scenario or present a threat to
groundwater quality;
Soil Flushing (with air stripping to remove VOCs also present in soils) may be employed
as a treatment technology to remove perchlorate from soils in areas where the risks to
groundwater are high, but excavation is infeasible due to depth;
Monitor groundwater at existing and new monitoring wells, drinking water wells,
irrigation wells and up-gradient sentinel wells, to evaluate the effectiveness of the
remedy. Additional monitoring wells may be required as necessary to evaluate the
effectiveness of this remedy; and
Manage groundwater within OU6 in coordination with the OU-3 and OU-5 groundwater
management plan to maintain water levels and to prevent adverse impacts on the remedy.
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Excavated or removed materials would be disposed of in an offsite, permitted and regulated
disposal facility, in compliance with waste characterization and appropriate State and Federal
disposal regulations.
Under this alternative, SVE will be performed to the extent possible to remove VOCs above
cleanup levels that present an unacceptable risk from soil vapor migration into indoor air under
an unrestricted or commercial/industrial use scenario. If the remedy performance evaluation
demonstrates that the SVE system will not reach RAOs, engineering controls from Alternative 3
would be implemented to prevent and mitigate unacceptable exposure.
ICs and engineering controls will also be established to protect the SVE system.
Under this alternative, where source removal/reduction is selected, remedial action will be
accomplished to the extent possible to remove all impacted soils above cleanup levels. As COCs
would remain beneath some of the buildings within OU-6 and it may take some time to implement
and complete the source removal/reduction activities included in this alternative, this Source
Removal/Reduction Alternative would also include the ICs, containment and engineering controls
described under the previous two alternatives. Examples would include actions taken with respect
to existing occupied buildings such as HVAC operational modifications and/or foundation venting
around/beneath existing occupied buildings located over areas that pose a potential risk for
commercial use.
ICs as described above in Section 2.10.2 (Alternative 2) would also be implemented as part of this
Alternative to restrict unacceptable land uses, require environmental evaluations, and establish
protection of engineered controls. This alternative will require source removal/ reduction in the
future in conjunction with building demolition or redevelopment if the environmental evaluation
demonstrates the COCs still exist above cleanup levels.
Figures 2-23 through 2-31 show the retained areas where Alternative 4 was the selected remedy.
2,10,5 Common Elements and Distinguishing Features of Each Alternative
These alternatives include common elements, as well as distinguishing features unique to each
option. The following discussion summarizes the common elements and distinguishing features
of Alternatives 1, 2, 3, and 4. As previously noted, not all of the alternatives were evaluated for
every site.
2.10.5.1 Common Elements
Common elements for the alternatives are as follows:
All of the alternatives, except for Alternative 1, include ICs and monitoring
All of the alternatives, except for Alternative 1, are compatible with intended site use and
reuse
Alternatives 2, 3, and 4 may result in restricted (i.e., industrial) land use
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2,10,5,2 Distinguishing Features
The distinguishing features of Alternative 1 (No Action) are that no remedial action would take
place under this alternative and there is no cost associated with this alternative.
The distinguishing feature of Alternative 2 (ICs) is that several sitewide ICs (including
groundwater ICs, areas subject to excavation restrictions, and Aerojet's Soil Excavation or
Grading, or Construction Debris Movement Notification Requirements for Soil Excavation and
Grading Requirements) are already in place throughout Aerojet and within OU-6; and adding
additional ICs to further protect human health and the environment is considered easily
implementable, with no risks to the community or site workers.
For Alternative 3 (Containment and Engineering Controls, incorporating Alternative 2 ICs),
implementation of the remedy would result in restricted land use (industrial) and long-term
O&M. Under this alternative, surface cover (e.g., asphalt, concrete, or building foundations)
would provide a physical barrier to prevent direct contact with contaminated soil and prevent
erosion and associated impacts to surface water. Subslab venting systems and/or subslab
depressurization systems foundation venting systems around and/or beneath existing buildings,
would reduce or prevent VOC intrusion into buildings. Sediment collection systems would also
prevent direct contact and surface water impacts because contaminated sediment would be
collected and removed. These will support the overall protectiveness of the remedy.
Under Alternative 4 (Source Removal/Reduction), unrestricted land use (residential) could be
obtained. The distinguishing feature of Alternative 4 (Source Removal/Reduction) is the
contamination is removed from the subsurface and in many cases, disposed offsite. Excavation
would remove impacted soil, SVE would be applied to areas containing elevated VOCs, soil
flushing and air sparging/SVE would be used in combination to also remove impacted soil where
excavation may not be feasible because of depth. The long-term reliability of this alternative and
treatment technologies is high because the waste is treated ex-situ or is removed from the site
and shipped offsite for disposal at an appropriate facility.
2.! I Summary of Comparative Analysis of Alternatives
In accordance with the NCP, the alternatives were evaluated by EPA using the nine criteria
(40 CFR, Section 300.430(e)(9)). For an alternative to be an acceptable remedy it must pass
EPA's two threshold criteria: (1) overall protection of human health and the environment, and
(2) compliance with ARARs. The No Action Alternative does not comply with the threshold
criteria and is not discussed beyond the threshold criteria. The comparative analysis of
alternatives based on the CERCLA criteria is included below and summarized in Table 2-12.
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Table 2-12: Comparative Analysis Summary for OU-6
Criteria
Alternative 1 -
No Action
Alternative 2 -
Institutional Controls
Alternative 3 -
Containment and Engineering Controls,
incorporating Alternative 2 ICs
Alternative 4 -
Source Removal/Reduction
Protection of
Human Health and
Environment
Would not reduce risk to
human health or the
environment.
Would reduce the potential for direct
exposure to contamination, but
contamination is left in place, so
some potential for direct contact and
impacts to groundwater remain.
With the exception of the protection
of groundwater, ICs would be
sufficiently protective of human
health.
Would reduce the potential risks to human
health and the environment and is
considered sufficiently protective.
However, potential risks from COCs
would not be eliminated because
contamination would remain in place.
Migration of VOCs to groundwater will
still occur.
Provides a higher level of protection
than Alternatives 2 and 3 because
contamination is removed or treated.
Alternative 4 is considered the most
protective.
Compliance with ARARs
Does not comply with
ARARs.
Partially meets criterion.
Partially meets criterion.
Meets criterion.
Long-Term Effectiveness
and Permanence
Does not provide long-term
effectiveness or permanence.
Alternative 2 relies on the restriction
or control of the land use by the
implementation, monitoring and
enforcement of ICs. The risk would
be reduced; however, concentrations
of COCs in soil and groundwater
would not be reduced.
Alternative 3 relies on both engineered
barriers and ICs to ensure that
unacceptable risks do not occur and is
therefore considered to be more effective
and permanent than Alternative 2.
Would provide greater long-term
effectiveness and permanence than
Alternatives 2 and 3 because
contamination would be removed.
Reduction in Toxicity,
Mobility, and Volume
Would not actively reduce
toxicity, mobility, or volume.
Reduction by natural
degradation processes only.
Would not actively reduce toxicity,
mobility, or volume. Reduction by
natural degradation processes only.
No reduction in toxicity or volume
through treatment. However, the presence
of engineered caps, vapor barriers, and
foundation venting and SVE systems
would reduce the mobility of COCs.
Would permanently remove the
majority of COCs, thereby reducing
toxicity, mobility, and volume.
Short-Term
Effectiveness
Not applicable for No Action.
No short-term risks to the
community or site workers would
occur due to the implementation of
this alternative.
Construction and operation of the passive
or active remediation measures included in
Alternatives 3 and 4 would pose minimal
short-term risks to workers and/or the
community.
Construction and operation of the
passive or active remediation measures
included in Alternatives 3 and 4 would
pose minimal short-term risks to
workers and/or the community.
Alternatives could be designed to
minimize short-term risk to workers
through health and safety measures.
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Table 2-12: Comparative Analysis Summary for OU-6
Criteria
Alternative 1 -
No Action
Alternative 2 -
Institutional Controls
Alternative 3 -
Containment and Engineering Controls,
incorporating Alternative 2 ICs
Alternative 4 -
Source Removal/Reduction
Implementability
Not applicable for No Action.
Readily implementable. There are no
technical difficulties associated with
implementing ICs. Least difficult
alternative to implement.
Readily implementable. Hie presence of
buildings over contaminated areas would
prevent the implementation of containment
technologies (Alternative 3) for several
years. All of the containment/operational
controls technologies are commercially
available and use standard construction
equipment and labor.
Readily implementable. The presence of
buildings over contaminated areas would
prevent the implementation of some
source reduction/removal technologies
(Alternative 4) for several years.
Excavation and SVE are commercially
available demonstrated technologies that
involve the use of standard construction
equipment and labor. Compared to
Alternatives 2 and 3, Alternative 4 is the
most difficult alternative to implement.
Cost3
$0
$107,000
$8,160,000
$20,727,000
State Acceptance
Not acceptable.
Acceptable
Acceptable
Acceptable
Community Acceptance
See Responsiveness Summary
(Appendix E)
This option is not generally
acceptable to the Community
See Responsiveness Summary
(Appendix E)
See Responsiveness Summary
(Appendix E)
See Responsiveness Summary
(Appendix E)
Note:
a Not all retained areas were evaluated for every alternative. For example, in the areas with risks to due vapor intrusion from contaminated groundwater, excavation (Alternative 4)
was not evaluated because excavation would not be applicable and implementable for this type of contamination.
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Overall Protection of Human Health and the Environment: Because ICs are a component
of Alternatives 2, 3, and 4, risks to human health and the environment (with the exception
of risks to groundwater) would be reduced and controlled through the implementation,
monitoring, and enforcement of ICs. With the exception of protection of groundwater, the
ICs component of Alternatives 2, 3, and 4 would be sufficiently protective of human health
with respect to this threshold criterion. Although COCs would remain in place and potential
risks to human health and the environment (including risks to groundwater) from soil and
groundwater COCs would not be eliminated under Alternative 3, the risk of exposure or
release would be significantly reduced or eliminated through engineered barriers and/or
operational controls. Alternative 4 would include actions to remove source materials or
reduce COCs to levels that would allow for restricted or unrestricted use and protection of
groundwater. Therefore, Alternative 4 would be the most protective of human health and the
environment (including groundwater).
Alternative 2 relies solely on ICs to achieve the additional protectiveness; therefore, it is not
considered to meet the NCP expectation of relying on engineered measures to reduce or
eliminate potential risks. Both Alternative 3 (Containment and Engineering Controls,
incorporating Alternative 2 ICs) and Alternative 4 (Source Removal/Reduction) include
remedial actions and would, therefore, meet the NCP expectation.
Compliance with ARARs: Cleanup actions for the all contaminated soil areas can be
designed and constructed to comply with ARARs. Where applicable, ICs will be effective in
limiting future land use.
Long-Term Effectiveness and Permanence: Although the concentrations of COCs in soil
and soil vapor would not be reduced under Alternative 2 (ICs), human health risk would
be reduced by restricting or controlling the land use. As Alternative 2 relies solely on
implementation, monitoring, and enforcement of ICs to ensure that unacceptable human
health risks do not occur, EPA has not generally considered ICs to be as effective or
permanent as alternatives that use engineered measures to ensure protectiveness. Under
Alternative 3 (Containment and Engineering Controls, incorporating Alternative 2 ICs), soil
containing PCBs, metals, and VOCs (soil vapor) would remain; and, therefore, residual risk
would remain. However, engineered barriers combined with implementation, monitoring,
and enforcement of additional ICs to control land uses would prevent exposure to
concentrations exceeding acceptable human exposure criteria and reduce risk. Under
Alternative 4 (Source Removal/ Reduction), the soil containing COCs exceeding acceptable
human and ecological criteria would be excavated and disposed of offsite, VOCs exceeding
acceptable criteria in soil sites would be addressed with SVE systems, and areas where other
COCs may be acting as a source to groundwater would be remediated using similar source
removal/reduction technologies, thereby permanently eliminating or reducing the potential
risks to acceptable levels. However, due to the presence of existing buildings and
infrastructure, some source materials and soil containing COCs cannot be removed or
remedial actions cannot be immediately implemented; and, therefore, residual risk would
remain until such time as the buildings/ infrastructure are removed prior to redevelopment.
ICs would be used to control land uses until such time as redevelopment allows for removal
of the remaining source materials and media containing concentrations of chemicals above
risk-based levels.
-------
Alternatives 2, 3, and 4 all include ICs. Several ICs have already been established,
implemented, and effective in restricting exposure for a number of years. These include the
Sacramento Consultation Zone Policy, the environmental covenant for the Carve-Out lands,
the PCD identifying areas subject to excavation restrictions, Aerojet's Soil Excavation or
Grading, or Construction Debris Movement Notification Requirements for Soil Excavation
and Grading Requirements, and the sitewide groundwater restriction ICs. Combining
engineered barriers with ICs that control land uses under Alternative 3 would provide
overlapping and redundant methods of protection. Long-term protection would be further
ensured through ongoing monitoring and maintenance of the presence and performance of
the engineered barriers and the effectiveness of the ICs. Excavation and offsite disposal
under Alternative 4 provides a permanent means of eliminating risks from source materials
and media containing concentrations of chemicals above risk-based levels. Assuming
implementation, monitoring, and enforcement of additional ICs, Alternative 2 would meet
process effectiveness and permanence. Alternative 3 relies on both engineered barriers and
ICs to ensure that unacceptable risks do not occur and is, therefore, considered to be more
effective and permanent than Alternative 2. Because Alternative 4 includes a mass
reduction/removal component, it would provide greater long-term effectiveness and
permanence than Alternatives 2 and 3.
Reduction of Toxicity, Mobility, or Volume through Treatment: Because Alternative 2
would not involve any new remediation systems, it would not provide any reduction in
toxicity beyond the natural attenuation of COCs that may occur in the unsaturated soil and
groundwater environments.
There would also be no reduction in toxicity or volume through treatment under Alternative 3.
However, the presence of engineered caps, vapor barriers, and foundation venting systems
would reduce the mobility of COCs. In addition, operation of foundation venting systems
would result in a minor reduction in the volume of VOCs. As there would be no reduction in
the toxicity, mobility, or volume through treatment under Alternative 2 and no reduction of
toxicity or volume under Alternative 3, no treatment residuals would be generated. Vapor
withdrawn by foundation venting systems is expected to contain only very low to minimal
concentrations of VOCs.
With respect to Alternative 4, excavation and disposal is the EPA's Presumptive Remedy for
soils containing non-volatile COCs and SVE is the Presumptive Remedy for soils containing
VOCs. As evaluated in the FS, these treatment technologies met the technical implementability
screening evaluation in the FS and would permanently remove the majority of COCs, thereby
reducing toxicity, mobility, and volume. As the excavated materials would be disposed of in an
offsite, permitted disposal facility, excavation would not result in treatment residuals. If SVE is
attempted for source removal/reduction, discharge from SVE systems may require treatment
to remove or reduce levels of VOCs that would otherwise be discharged to the atmosphere.
If vapor phase granular activated carbon is used, it would be shipped to an offsite facility for
regeneration or destruction.
Short-Term Effectiveness: Because no remedial action other than implementation of
additional ICs would be taken under Alternative 2, no additional short-term risks to the
community or to workers from implementation of this action would occur. Similarly, no
environmental impact from construction activities would occur. Construction and operation
131
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of the passive or active remediation measures that might be included in Alternatives 3 and 4
would pose minimal short-term risks to workers and/or the community. Standard Occupational
Safety and Health Administration precautions necessary to protect worker safety during
construction would be employed. Short-term environmental impact from construction activities
is expected to occur.
Implementation, monitoring, and enforcement of ICs limiting properties to land uses that
would not result in exposure greater than risk-based levels (Alternatives 3 and 4) would
ensure that the RAOs 1 and 2 are met.
With respect to the time until RAOs would be achieved, it is estimated that it would take
approximately 6 months to 1 year to implement additional ICs (Alternatives 2, 3, and 4) and
approximately 2 to 3 years to conduct the necessary evaluations, prepare remedial designs,
and construct the engineered barriers (Alternative 3) or implement source reduction/ removal
measures (Alternative 4). Operation of source reduction measures such as SVE might require
additional time to implement if treatability studies or pilot testing are needed.
Implementability: Technically, ICs (Alternative 2) would be easily implemented, as would
the ICs component of Alternatives 3 and 4. There are no technical difficulties associated with
implementing additional ICs as no physical facilities would be constructed, and Aerojet and
the regulatory agencies have already negotiated ICs for the Carve-Out lands. For those
portions of OU-6 under Aerojet's ownership, there would appear to be no institutional
impediments to reaching agreement on acceptable language. From an administrative
implementability perspective, there are several areas within OU-6 where existing buildings
or structures would remain in service or would not be demolished until future development
plans are implemented. Their presence would prevent the implementation of containment
technologies (Alternative 3) and some source reduction/removal technologies (Alternative 4)
for several years, though the building itself will help prevent unacceptable exposure and
provide some containment.
For Alternative 3 (Containment and Engineering Controls, incorporating Alternative 2 ICs),
construction and maintenance of engineered barriers is technically feasible. Construction of
asphalt or concrete caps and maintenance of existing asphalt and concrete over areas having
COCs in the vadose zone can easily be performed. Construction of subslab depressurization,
subslab venting, or alternative system designed to prevent intrusion to indoor air as part of
new construction is a standard technology that does not pose any technical issues relative to
implementability. Installation of foundation venting systems around or beneath existing
buildings may be constrained by the presence of extensive underground utilities and
landscaping, but these conditions are not expected to prevent or otherwise limit the
implementability or effectiveness of these technologies. All of the containment and
engineering controls technologies are commercially available and use standard construction
equipment and labor. The necessary materials and specialist personnel are easily attainable.
Excavation and offsite disposal of soil containing COCs and/or implementation of SVE
systems under Alternative 4 (Source Reduction/Removal) are technically feasible. SVE for
mass removal would be more complicated to implement under and around existing buildings
because of extensive foundation systems and numerous underground existing utilities. To
evaluate soil conditions and vapor permeability, pilot testing of SVE systems may be needed
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to assess design parameters of SVE for mass reduction/removal. Alternative 4 would present
few administrative difficulties and would require minor coordination with other agencies.
Excavation, offsite disposal in a permitted and regulated disposal facility and SVE are all
commercially available, demonstrated technologies that involve the use of standard
construction equipment and labor.
In summary, from both the administrative and technical perspectives, Alternative 2 (ICs)
would be the easiest to implement, followed by Alternative 3 (Containment and Engineering
Controls, incorporating Alternative 2 ICs). Alternative 4 (Source Reduction/Removal) would
be the most difficult to implement.
Cost: A summary of the estimated costs associated with each alternative is presented in
Table 2-12. The basis for the costs, and the methodology and information used to develop the
costs are provided in Appendix D.
The cost estimates for each alternative were prepared in accordance with current EPA guidance
with respect to level of accuracy and discount rate (i.e., 1.9 percent). For comparison purposes,
the estimated total capital cost, estimated annual monitoring costs, estimated annual O&M
costs, and estimated 30-year present worth cost estimates are presented in Table 2-12 and in
the tables in Appendix D for each of the alternatives. The 30-year present worth costs for
Alternative 2 (ICs) are less than the other two alternatives. In general, for most of the MAs
within OU-6, 30-year present worth costs for Alternative 3 (Containment and Engineering
Controls, incorporating Alternative 2 ICs) are less than those for Alternative 4 (Source
Reduction/Removal).
State Acceptance: The DTSC and Central Valley RWQCB support the selection of the
remedial alternatives for the 81 areas addressed by this ROD. DTSC and the RWQCB
provided invaluable input to EPA throughout the RI, FS, and this ROD review. EPA
addressed certain State comments by DTSC and RWQCB regarding final human health and
ecological cleanup standards. For example, EPA adopted DTSC HHRANote 3, portions of
CCR Title 27 and Title 23, State Water Resources Control Board Resolution No. 92-49, the
Porter-Cologne Water Quality Control Act, and the Central Valley RWQCB DLM for
Waste Classification and Cleanup Level Determination. EPA has adopted only portions of
the ARARs identified by DTSC and the Central Valley RWQCB, and it is the position of
DTSC and the Central Valley RWQCB that there are a number of additional ARARs that are
applicable requirements. State ARARs based on CCR Titles 23 and 27 that have been
accepted by EPA in this ROD have been included as ARARs based on limited application to
certain site-specific portions of the OU-6 selected remedy. Table 2-13 outlines the site-
specific ARARs adopted by EPA, and DTSC or RWQCB's position concerning why certain
ARARs are considered applicable for this particular ROD. DTSC and RWQCB claim that
these applicable requirements include, but are not limited to, certain provisions of Titles 23
and 27 as outlined in Table 2-13, and as referenced in the Administrative Record. For
example, the Central Valley RWQCB maintains that a waste left in place following
remediation within OU-6 may constitute a "waste management unit" for the purposes of
CCR Title 23 concerning the discharge of hazardous waste to land for treatment, storage, or
disposal; and CCR Title 27 as applicable to discharges of designated waste, which includes
nonhazardous solid waste that could be released in concentrations exceeding applicable water
quality objectives or that could reasonably be expected to affect beneficial uses of the waters
133
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of the State. DTSC and the Central Valley RWQCB reserve any and all rights to assert any
state law provisions referenced in this ROD without any waiver and no prejudice to DTSC or
the Central Valley RWQCB.
The EPA disagrees with DTSC and the Central Valley RWQCB about the applicability of
certain state law provisions as noted above and as referenced in Table 2-13 for the remedial
actions being selected in this ROD. However, DTSC and the Central Valley RWQCB agree
that there is no substantive technical dispute as to the selected remedies and cleanup levels for
this ROD. Accordingly, DTSC and the Central Valley RWQCB agree to concur with this ROD.
Community Acceptance: The CAG has regularly met with EPA, Aerojet, DTSC, RWQCB
and others to discuss issues related to the site and comment on cleanup plans. The CAG has
actively participated in discussions with EPA throughout the development of the BOU OU6
RI/FS Report and Proposed Plan and is in general agreement with the selected remedies.
The CAG requested additional time to submit comments on the Proposed Plan due to the
complexity of the document. The public comment period was extended out an additional
120 days, making the entire public review period May 8 through September 20, 2013.
Comments received by EPA reflect general concerns with the use of conservative cleanup
goals, especially for perchlorate; conservative measures to ensure that future residents are not
exposed to site contaminants; and appropriate groundwater monitoring and ICs.
The NCP establishes an expectation that EPA will use treatment to address the principal threats
posed by a site wherever practicable. The principal threat concept applies to source materials that
are highly mobile or highly toxic and cannot be reliably controlled in place or that would present
a significant risk to human health or the environment should exposure occur. A source material
includes or contains hazardous substances, pollutants, or contaminants that act as a reservoir for
migration of contamination to groundwater, surface water, or air or that act as a source for direct
exposure.
None of the OU-6 remedial action areas have liquid or highly mobile wastes; however, several
areas have high concentrations of toxic compounds that may be considered principal threat
wastes. Examples of areas with high concentrations of toxic compounds include (but are not
limited to): AE-R-2 (Aroclor-1254 concentrations resulting in a residential child HI of 42),
AE-R-3 and AE-R-6 (PAH concentrations resulting in a residential ILCR greater than 10"3),
AE-SV-R-2 and AW-SV-R-1 (VOC concentrations resulting in an ILCR greater than 10"3 and an
HI of 46), CP2-R-7 (various COC concentrations resulting in an HI of 14), and CP2-SV-R-2
(1,2-DCA concentrations resulting in a residential ILCR of greater than 10"2 and an HI of 1,300).
The Alternative 4 will reduce the volume, toxicity, and/or mobility of contaminants, meeting the
statutory preference for treatment as a principal element. Actions, such as ICs and engineering
controls, to prevent exposure will be required until the contamination remaining on site is
remediated.
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Table 2-13: Description of ARARs for Selected Remedies
Clu'iniiiil-Spi'iilli' ARARs
Federal
Soil
EPA Regional Screening
Levels (RSLs)(2015)
TBC
EPA has developed RSLs, which are risk-
based levels that are used to screen sites that
may require additional investigation or
possible remediation. RSLs also may be
considered in setting soil cleanup levels or
groundwater cleanup levels in the absence of
promulgated values for contaminants.
RSLs are considered in setting soil cleanup levels,
including soil vapor levels, to be protective for
residential, commercial, or industrial land use
scenarios, as set forth in Table 2-2. Groundwater
cleanup values are based on MCLs, California
PHGs or California Drinking Water Notification
Levels.
Federal
Soil
Toxic Substances Control
Act (TSCA), 15 USC
Section2605(e)( 1 )(A);
40 CFR 761.61
Applicable
Sets cleanup and disposal requirements for
PCB spills.
TSCA establishes federal minimum requirements
for PCB soil cleanup for protection of human
health. Site-specific cleanup levels were derived
through a risk assessment approach, based on
RSLs, which are lower than the TSCA minimum
cleanup requirement of 1 ppm for unrestricted use
in high-occupancy areas.
State
Groundwater/
Surface Water
Water Quality Control
Plan (Basin Plan) for the
Sacramento River and
San Joaquin River Basins
(2009 revisions), adopted
in accordance with
California Water Code,
Division 7, Sections 13240
and 13050 (Porter-Cologne
Act); Chaps. II and III
Relevant and
Appropriate
Those portions of the Basin Plan that set out
the designated uses (i.e., beneficial uses) and
the water quality objectives for surface
waters.
The designated use for the aquifer at the Aerojet
Site is municipal and aquatic water supply.
The cleanup levels for the contaminated surface
water comply with the Basin Plan's water quality
objectives based upon such use. The aquifer
designation is used to determine applicable
soil cleanup levels that will allow for the
groundwater to eventually attain the water quality
objectives in the Basin Plan in the final
groundwater remedy.
State
Groundwater and
Soil
SWRCB Resolution No.
88-63 (Sources of
Drinking Water Policy)
Applicable
Designates all ground and surface waters of
the State as drinking water except where TDS
is greater than 3,000 ppm, the well yield is
less than 200 gpd from a single well, the
water is a geothermal resource or in a water
conveyance facility, or the water cannot
reasonably be treated for domestic use using
either best management practices or best
economically achievable treatment practices.
The aquifers under the Aerojet Site have been
identified as sources of drinking water by this
resolution. Federal and State MCLs are being used
to derive the site-specific soil cleanup levels for
protection of groundwater.
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Table 2-13: Description of ARARs for Selected Remedies
Action to be Taken to
Authority Medium Requirements Status Synopsis of Requirements Attain Requirements
State
Soil for Protection
of Groundwater
Staff Report of the
RWQCB, Central Valley
Region DLM for Waste
Classification and Cleanup
Level Determination
TBC
Provides guidance on how to classify wastes
according to Title 27, CCR, Division 2,
Subdiv.l/ Title 23, CCR, Division 3,
Chapter 15, Article 10.
Performance standard to be considered in
determining the classification of wastes and
contaminated soils, as set forth in Table 2-2.
State
Soil for Protection
of Groundwater
SWRCB Resolution
No. 92-49 IIIG (As
amended April 21, 1994)
Porter-Cologne Water
Quality Control Act
(California Water Code
Sections 13000, 13140,
13240, 13260, 13263,
13267, 13300, 13304,
13307)
Relevant and
Appropriate
Promotes attainment of either background
water quality, or the best water quality that is
reasonable if background levels of water
quality cannot be restored.
Relevant and appropriate to cleanup of discharges
to soil that may affect water quality.
Comment: EPA recognizes 92-49 III.G only as
relevant and appropriate. The RWOCB maintains
that all of92-49 is applicable or relevant and
appropriate.
State
Soil and Soil
Vapor in Ambient
Air
Minimum Standards for
Health and Ecological
Risk Assessments;
California Health & Safety
Code ง25356.1.5(b)
DTSC HHRA Note 3
Relevant and
Appropriate
Risk assessments for remedy selection must
not only meet NCP requirements, but also
must include most current sound scientific
methods, knowledge, and practices of public
health and environmental professionals.
Use when determining the soil and soil vapor
in ambient air cleanup levels, as set forth in
Table 2-3.
State
Vapor Intrusion
DTSC Vapor Intrusion
Mitigation Advisory,
California Health and
Safety Code ง25356.
1.5(b)
October 1, 2011
TBC
The Advisory provides guidance concerning
engineering controls and response actions
designed to interrupt or monitor the vapor
intrusion pathway and to ensure public safety
until the source of volatile chemical
concentrations causing the vapor intrusion
risk has been restored to concentrations at or
below levels considered safe for human
exposure. The Advisory provides a
framework that guides the process for
selecting a site-specific mitigation
technology such as SSD or SSV systems or
an alternate mitigation system that may prove
to have results equal to or better than those of
SSD or SSV systems.
Consider in the selection, design, and long-term
monitoring of vapor intrusion technologies to
reach vapor intrusion mitigation objectives.
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Table 2-13: Description of ARARs for Selected Remedies
Action to be Taken to
Authority Medium Requirements Status Synopsis of Requirements Attain Requirements
State
Soil and
Groundwater
Title 27, CCR, ง 20430
Title 23, CCR, ง2550.10
Porter-Cologne Water
Quality Control Act
(California Water Code
Sections 13140-13147,
13172, 13260, 13263,
13267, 13269)
Relevant and
Appropriate
Requires implementation of corrective action
measures that ensure cleanup levels (i.e.,
water quality protection standard established
under Section 2550.2) are achieved
throughout the zone affected by the release
by removing the waste constituents or
treating them in place. Source control may
be required. Also requires monitoring to
determine the effectiveness of the corrective
actions.
If water quality is threatened, this section applies
to all soil cleanup activities.
Comment: Although EPA has identified certain
selected sections of Titles 23 and 27 as relevant
and appropriate to this remedy, the RWOCB
maintains that Titles 23 and 27 apply broadly to
this cleanup. Specifically, the RWOCB cites the
following as either applicable or relevant and
appropriate to this remedy: 23 CCR งง 2510,
2511, 2520, 2521, 2550.0-2550.8, & 2580;
27 CCR งง20080, 20090, 20200, 20210, 20220,
20230, 20385-20435, 20950 & 22207. EPA does
not agree that all of these provisions are ^4R4Rs
for this remedy.
State
Soil
Title 27, CCR, ง 20430
Title 23, CCR, ง2550.10
Porter-Cologne Water
Quality Control Act
(California Water Code
Sections 13140-13147,
13172, 13260, 13263,
13267, 13269)
Relevant and
Appropriate
Requires an assessment of the nature and
extent of the release, including a
determination of the spatial distribution and
concentration of each constituent.
Applies to sites at which monitoring results show
statistically significant evidence of a release.
Location-Specific ARARs
Federal
Floodplain and
wetland protection
Executive Order
Nos. 11990 and 11988
TBC
Require avoidance of adverse effects,
minimization of potential harm, and
restoration and preservation of natural and
beneficial values of floodplains.
Constructing groundwater treatment facilities in a
100-year flood plain will be avoided. If it cannot
be avoided, the potential harm to the flood plain
shall be minimized.
Federal
Within 100-year
flood plain
40 CFR Section 264.18(b)
(2010) and 22 CCR
Section 66264.18(b)
Applicable
A RCRA facility located in a 100-year flood
plain must be designated, constructed,
operated, and maintained to prevent washout
of any hazardous waste by a 100-year flood.
Because any new treatment facilities in OU-6 may
generate hazardous waste, any such facility
constructed within a 100-year flood plain must
comply with this requirement.
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Table 2-13: Description of ARARs for Selected Remedies
Action to be Taken to
Authority Medium Requirements Status Synopsis of Requirements Attain Requirements
Federal
Sites in or Eligible
for Inclusion in
the National
Register of
Historic Places
Substantive portions of the
National Elistoric
Preservation Act, 16 USC
Sections 470, et seq.;
36 CFR Part 800 (2010)
Applicable
Provides for protection of sites with historic
places and structures. Federal agencies are
required to take into account their
undertakings on historic properties and afford
the State Elistoric Preservation Office a
reasonable time to comment.
Applicable if a federal undertaking (cleanup)
could adversely affect historic properties that are
included in or eligible for inclusion in the National
Register of Historic Places. The proposed remedial
alternatives are not expected to alter or destroy
any known prehistoric or historic archeological
features in OU-6 of the Aerojet Site. However,
because there is always a possibility that buried
historic or prehistoric remains could be discovered
during such actions, this requirement would
include action to address such areas.
Federal
Endangered
Species or
Threatened
Species
Substantive portions of the
Endangered Species Act
of 1973, 16 USC 1531 et
seq.; 50 CFR Parts 200 and
402 (2010)
Applicable
Federal agencies are required under Section 7
of the ESA to ensure that their actions do not
jeopardize the continued existence of a listed
species or result in destruction or adverse
modification of its critical habitat (16 USC
1536). If the proposed action may affect the
listed species or its critical habitat,
consultation with the USFWS mav be
required (50 CFR 402.14). Additionally,
Section 9 of the ESA prohibits the illegal
taking of a listed species
(16 USC 1538(a)(1).
Any action that may impact or threaten to impact
Federal threatened or endangered species shall
comply with this requirement.
State
California Endangered
Species Act, Cal. Fish and
Game Code Section 2080
Applicable
Prohibits the illegal taking of plant and
animal species designated as either
threatened or endangered in the state of
California.
Any action that may impact or threaten to impact
State threatened or endangered species shall
comply with this requirement. For EPA's risk
assessment purposes, all State-designated
special-status species are treated as if listed as
threatened or endangered. Applicable to
state-listed species that are not protected under the
Federal ESA.
Federal
Listed Migratory
Birds
Migratory Bird Treaty Act;
16 USC Sections 703,
et seq.
Applicable
Prohibits the illegal taking of migratory birds.
The Aerojet Site may be a habitat for the
Burrowing Owl, a species of concern in California.
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Table 2-13: Description of ARARs for Selected Remedies
Authority
Medium
Requirements
Status
Synopsis of Requirements
Action to be Taken to
Attain Requirements
Federal
Areas Affecting
Streams or Rivers
Fish and Wildlife
Coordination Act, 16 USC
661 et seq.
Applicable
Requires Federal agencies that construct,
license, or permit water resource
development projects that modify any
streams or water bodies to first consult with
the USFWS (and the National Marine
Fisheries Service in some instances) and
State fish and wildlife agency regarding the
impacts on fish and wildlife resources and
measures to mitigate these impacts.
Applicable if a water body will be controlled or
modified as a result of a federal agency action,
license, or permit.
State
Streambed or
Riverbed
Alterations
Substantive Requirements
of Cal. Fish and Game
Code Section 1602
Applicable
Prohibits substantial diversion or obstruction
of the natural flow of, or a substantial change
of the bed or channel of, a river, stream or
lake. Prohibits the deposit or disposal of
debris or waste where it may pass into any
river, stream, or lake.
Applies to grading and filling activity.
State
Restrictions
Relating to Land
and Groundwater
California Civil Code
Section 1471; 22 CCR
Section 67391.1(a), (d)
(2010)
Relevant and
Appropriate
Substantive requirements for placing an
environmental restrictive covenant on
contaminated land in the state of California.
Requires Aerojet to record environmental
restrictive covenants on contaminated land and to
name EPA as a third-party beneficiary in the
covenants.
Comment: EPA specifically identifies subsections
(a) and (d) of 22 CCR 67391.1 as relevant and
appropriate for this ROD. DTSC's position is that
the provisions of the entire 22 CCR 67391.1 are
applicable requirements at this Site.
Action-Specific ARARs
Federal
Dredge and Fill
33 USC Sections 1251, et
seq. and 40 CFR Parts 230
and 231 (2010)
Relevant and
Appropriate
Regulates discharge of dredged or fill
material into waters of the U.S., including
wetlands.
Substantive portions applicable. Permit is not
required for onsite activities.
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Table 2-13: Description of ARARs for Selected Remedies
Authority
Medium
Requirements
Status
Synopsis of Requirements
Action to be Taken to
Attain Requirements
Federal
Generation of
Waste from
Construction and
Operation due to
Remedial Action
Selected
40 CFR Part 261 Subparts
A, B, C, and D (2014) and
22 CCR Section 66261.3
(2010)
Applicable
Establishes procedures and numeric limits for
identification and management of
characteristic hazardous wastes, listed
hazardous wastes, and State-only
(non-RCRA) hazardous wastes.
These requirements are applicable to management
of waste materials generated as a result of
construction of the selected remedial action or
operation of a groundwater treatment plant.
Consistent with prior RODs at this Site, the
hazardous wastes at this Site are RCRA
characteristic hazardous wastes. Based on the
information available to EPA, no RCRA-listed
hazardous wastes have been generated at this Site.
Federal
Generation of
Waste from
Construction and
Operation due to
Remedial Action
Selected
40 CFR Section 262.11
(2010) and 22 CCR
Section 66262.11 (2010)
Applicable
Requires waste generators to determine if
wastes are hazardous wastes, and establishes
procedures for such determinations.
These requirements are applicable to management
of waste materials generated as a result of
construction of the selected remedial action or
operation of a groundwater treatment plant.
Federal
Storage of
Hazardous Wastes
for Treatment or
Disposal Offsite
40 CFR Section 262.34
and 22 CCR Section
66262.34 (2010)
Applicable
Specifies maximum amounts and maximum
periods for accumulation of hazardous waste
onsite under generator status.
These requirements are potentially applicable to
management of waste materials generated as a
result of construction of the remedial action and
operation of any groundwater treatment plant.
To the extent that the wastes are located in an
existing area of contamination, these provisions
may not be triggered, as provided by EPA
guidance.
Federal
Discharge to
Inland Surface
Water
National Toxics Rule,
40 CFR Sections 131.6
and 131.38(2010)
(California Toxics Rule)
Applicable
Establishes the appropriate aquatic and
human health criteria for priority toxic
pollutants in inland surface waters and
enclosed bays and estuaries. Included in the
National Rule are EPA-promulgated specific
criteria for certain water bodies in California,
the presence or discharge of which could
reasonably be expected to interfere with
maintaining designated uses.
Applicable for offsite discharge subject to NPDES
permits and for onsite discharge subject to
substantive requirements of a NPDES permit.
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Table 2-13: Description of ARARs for Selected Remedies
Action to be Taken to
Authority Medium Requirements Status Synopsis of Requirements Attain Requirements
State
Discharge to
Surface Water
Section IV-16 (Policy for
Application of Water
Quality Objectives) of the
Basin Plan for Sacramento
River and San Joaquin
River Basins (2009 rev.)
TBC
Allows for the use of mixing zones as part of
a determination of whether water quality is
being maintained in the receiving water.
By considering mixing zones, the point of
compliance for evaluating the achievement of
RAOs may be modified as part of the remedy.
Federal
Discharge to
Surface Water
NPDES Permit, 40 CFR
Parts 122 and 125 and 23
CCR Sections 2235 et seq.
Applicable
Establishes treatment and monitoring
requirements for discharges to surface water.
Discharge to surface water onsite will comply with
the substantive requirements of a NPDES Permit.
Discharge to surface water offsite will require a
NPDES Permit.
Federal
Stormwater
Management
40 CFR Part 122.26 (2010)
and 23 CCR Section 2235
et seq. (2010)
Applicable
Establishes, monitoring, and pollutant control
requirements for stormwater from industrial
activities.
The substantive requirements would be applicable
if construction activities associated with the
remedial action disturb an area of 1 acre or more.
Federal
Air
Air Emission Standards for
Process Vents; 40 CFR
Sections 265.1030-1035
(2010); 22 CCR Sections
66265.1030-66265.1035
Relevant and
Appropriate
Applies to treatment, storage, and disposal
facilities with process vents associated with
solvent extraction or air or steam stripping
operations managing RCRA hazardous
wastes with organic concentrations of at least
10 ppm. These operations must reduce total
organic emissions below specified device to
reduce total organic emissions by 95 percent
by weight.
The requirements are relevant and appropriate for
groundwater extraction and air-stripping
operations for the remedy where organic
concentrations are at least 10 ppm.
State
Air
Sacramento Metropolitan
Air Quality Management
District Rules
Cal. Health and Safety
Code, 39602, 39606,'
40001
Rule 402 Nuisance
Rule 403 Fugitive Dust
Rule 404 Particulate
Matter
Rule 441 Organic Solvents
Applicable
Limits emissions of dust, particulates, and
organic solvents to the air.
Substantive aspects of SMAQMD Rules 402, 403,
404, or 441 may apply to remedial actions
involving ground-disturbing activities, and to
emissions from treatment facilities.
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Table 2-13: Description of ARARs for Selected Remedies
Authority
Medium
Requirements
Status
Synopsis of Requirements
Action to be Taken to
Attain Requirements
State
Surface Water
SWRCB Resolution No.
68-16 ("Antidegradation
Policy")
Applicable
Requires that high-quality surface and ground
waters be maintained to the maximum extent
possible.
May apply to discharges of waste to surface waters
of the State that may be impacted by the cleanup
where substantive NPDES requirements have not
been met.
State
Surface Water
Title 27, CCR, Section
21400
Porter-Cologne Water
Quality Control Act
(California Water Code
Sections 13140-13147,
13172, 13260, 1323,
13269).
Relevant and
Appropriate
Requires surface impoundments to be closed
by removing and treating all free liquid and
either removing all remaining contamination
or closing the surface impoundment as a
landfill.
If water quality is threatened, this section is
relevant and appropriate for excavations and diked
areas where wastes containing free liquids were
discharged.
ESA = Endangered Species Act
gpd = gallons per day
MCL = maximum contaminant level
NPDES = National Pollutant Discharge Elimination System
PHG = Public Health Goal
ppm = parts per million
SMAQMD = Sacramento Metropolitan Air Quality Management District
TDS = total dissolved solids
TSCA = Toxic Substances Control Act
USFWS = U.S. Fish and Wildlife Service
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2.13 Selected Remedies
Based on current information, EPA is selecting ICs (Alternative 2), Containment and
Engineering Controls, incorporating Alternative 2 ICs (Alternative 3), and Source Removal/
Reduction (Alternative 4) as the remedies for the contamination in OU-6. EPA believes these
alternatives meet the threshold criteria and provide the best balance of tradeoffs among the
alternatives. EPA expects the preferred alternatives to satisfy the following statutory
requirements of CERCLA Section 121 (b): (1) to be protective of human health and the
environment; (2) to comply with ARARs; (3) to be cost-effective; (4) to use permanent solutions
and alternative treatment technologies or resource recovery technologies to the maximum extent
practicable; and (5) to satisfy the preference for treatment as a principal element.
2.13.1 Alternative 2 - Institutional Controls
The principal factors considered in selecting Alternative 2 for three remedial action areas in
OU-6 (Appendix B) were that by limiting exposure to contaminants through the implementation
of ICs, the overall protection of human health at the sites would be increased. This alternative
will comply with state and federal human health requirements, provide both long- and short-term
effectiveness, and is considered implementable for the nine remedial action areas proposed.
2.13.2 A1 I - Containment unci Engineering Controls, incorporating
Al : ICs
The principal factors considered in selecting Alternative 3 for 11 remedial action areas in OU-6
(Appendix B) were that with containment and the application of engineering controls,
contaminant exposure would be limited. This would greatly reduce the risk and increase the
overall protection of human health and the environment at the sites through containment and
engineered controls, along with ICs. This alternative complies with state and federal
environmental requirements; it provides both long- and short-term effectiveness; and it is
considered implementable for those seven remedial areas.
2.13.3 Alternative 4 - Source Removal/Reductions
The principal factors considered in selecting Alternative 4 for 67 of the 81 remedial action areas
in OU-6 (Appendix B) were the removal or reduction of source material, which would greatly
improve the overall protection of human health and the environment at the sites. Excavating
contaminated soils and offsite disposal, as well as SVE and along with ICs, reduces exposure to
contaminants by limiting toxicity, mobility, and/or volume. This alternative complies with state
and federal environmental requirements, provide both long- and short-term effectiveness, and are
considered implementable.
2.13.4 Summary of Additional Rationale for the Selected Remedies
In addition to the rationale presented in Section 2.13, Appendix B presents other principal factors
considered for the rationale at each of the remedial action areas in OU-6. EPA believes that once
the selected remedies are implemented, property(ies) will be suitable for reuse. Although the
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selected remedies are not always the least expensive, the selected remedies are cost-effective, and
the additional cost is generally supported by a greater degree of protectiveness at each site.
2.13.5 Expected Outcomes of the Selected Remedies
The expected outcomes of the selected remedies are the removal or containment of soil and soil
vapor contamination to protect human and ecological receptors from unacceptable exposure,
mitigation of further impacts to groundwater, and the restoration of the contaminated areas to
levels protective of expected future land uses. Additionally, the remedy will monitor and control
remaining contamination.
2.13.6 Greener Cleanups Considerations
Consistent with EPA Region IX's Greener Cleanups Policy (EPA, 2009b), Aerojet should
evaluate a range of practices, strategies, and technologies to support the implementation of
Greener Cleanups. The Greener Cleanups approach should reflect the following core elements:
Reduce total energy use and apply renewable energy sources
Reduce air pollutants and greenhouse gas emissions
Reduce water use and impacts to water resources
Reduce, reuse, and recycle materials and waste
Protect and restore land and ecosystems
As part of the Greener Cleanups approach, the PRP will prepare a Greener Cleanups Assessment
for submittal and approval, as part of the Remedial Design Plan. This assessment will evaluate
opportunities to apply Greener Cleanup best management practices (BMPs) and reduce the
environmental footprint throughout all remedial actions.
The Greener Cleanups Assessment shall consider and outline, at a minimum, the following
touchstone practices:
Renewable energy to power the cleanup remedy
Clean diesel fuels and technologies for onsite equipment and transport
Reuse or recycling of demolition debris
Water from recycled sources and recycling of treated water
The assessment should make use of resources such as EPA's Greener Cleanup Principles
(EPA, 2009a), EPA's Green Remediation Strategy (EPA, 2010), the ASTM Greener Cleanups
Standard Guide (ASTM, 2013), the Region IX Greener Cleanups Policy (EPA, 2009b), and
resources on cluin.org (EPA, 2015), in considering these touchstone practices and in identifying
any additional Greener Cleanups best management practices at the site.
The implementation of the touchstone practices, or any additional Greener Cleanups BMPs,
does not change cleanup goals, or how and why cleanup decisions are made, but calls for more
environmentally friendly methods of implementing the cleanup. The cleanup at the Aerojet
Superfund Site must meet all statutory and regulatory requirements of our cleanup programs,
144
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such as satisfying threshold requirements for protectiveness and meeting other site-specific
cleanup objectives.
2.14 Statutory Determinations
Under CERCLA Section 121 and the NCP, the lead agency must select remedies that are
protective of human health and the environment, comply with ARARs (unless a statutory waiver
is justified), are cost-effective, and use permanent solutions and treatment or resource recovery
technologies to the maximum extent practicable. In addition, CERCLA includes a preference for
remedies that employ treatment that permanently and significantly reduces the volume, toxicity,
or mobility of hazardous wastes as a principal element and a bias against offsite disposal of
untreated wastes. The following sections discuss how the selected remedies meet these statutory
requirements and explain the 5-year review requirements for the selected remedies.
2.14.1 Protection of Human Health and the Environment
Under its legal authorities, EPA's primary responsibility at Superfund sites is to undertake
remedial actions that achieve adequate protection of human health and the environment.
The selected remedies of ICs, containment and engineering operation controls, and source
removal/reduction reduce or eliminate unacceptable human and ecological exposure to
contamination remaining onsite.
If no action is taken on contaminated soil and soil vapor areas, potential exposure for either
residents or workers would exceed acceptable risk levels, and impacts to groundwater may
continue to occur, increasing the eventual cost, difficulty, and time required to restore the aquifer.
2.14.2 Compliance with Applicable or Relevant unci Appropriate Requirements
Remedial actions selected under CERCLA must comply with all ARARs under federal
environmental laws or, where more stringent than the federal requirements, state environmental
or facility siting laws. Where a state has delegated authority to enforce a federal statute, such as
RCRA, the delegated portions of the statute are considered to be a federal ARAR unless the state
law is broader in scope than the federal law. ARARs are identified on a site-specific basis from
information about site-specific chemicals, specific actions that are being considered, and specific
features of the site location. There are three categories of ARARs: (1) chemical-specific
requirements; (2) location-specific requirements and (3) action-specific requirements.
Chemical-specific ARARs are health- or risk-based numerical cleanup or containment values or
methodologies which, when applied to site-specific conditions, result in the establishment of
numerical values for COCs at the site. These values establish the acceptable amount or
concentration of a COC that may be found in or discharged to the ambient environment.
Location-specific ARARs are restrictions placed on concentrations of hazardous substances or
the conduct of activities because of the special locations, which have important geographical,
biological or cultural features. Examples of special locations include wetlands, flood plains,
sensitive ecosystems and seismic areas.
145
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Action-specific ARARs are technology-based or activity-based requirements or limitations on
actions to be taken to handle hazardous wastes. They are triggered by the particular remedial
activities selected to accomplish a remedy.
Where no ARARs exist for a given chemical, action or location, EPA may consider non-
promulgated federal or State advisories and guidance as To Be Considered criteria (TBC).
Although consideration of a TBC is not required, if standards are selected based on TBC,
those standards are legally enforceable as performance standards. TBCs selected in Tables 2-2
and 2-3 are performance standards.
Table 2-13 provides a complete list of ARARs for OU-6. Performance standards in the
contaminated soil areas for soil contaminants and soil vapor are the risk-based soil concentrations
for unrestricted use listed in Tables 2-2 and 2-3. Restrictions on the future use of contaminated
soil areas that have not attained residential cleanup objectives will be implemented through a
recorded declaration of Covenants and Environmental restrictions pursuant to 22 California Code
of regulations, section 67391.1 (a) & (d), whereby Aerojet covenants to impose these restrictions.
2.14.3 Cost Effectiveness
EPA must consider the cost-effectiveness of the proposed remedy. The NCP defines a
cost-effective remedy as one whose "costs are proportional to its overall effectiveness." More
than one remedial alternative can be cost-effective, and EPA is not required to select the most
cost-effective alternative. Overall effectiveness is determined by evaluating three of the
balancing criteria: long-term effectiveness; reduction in toxicity, mobility, and volume through
treatment; and short-term effectiveness.
The costs associated with each of the selected alternatives for each of the retained areas are
presented on Tables D-l through D-3 in Appendix D. The total present worth cost for the
selected remedies is $25,318,000 (see Table D-4 in Appendix D).
EPA judges the No Action Alternatives as neither protective of human health nor cost-effective.
2.14.4 Utilization of Permanent Solutions unci Alterni logics to the
Maximum Extent Practicable
EPA has determined that the selected remedies represent the maximum extent to which
permanent solutions and treatment technologies can be used in a practicable manner. Of those
alternatives that are protective of human health and the environment and comply with ARARs,
EPA has determined that the selected alternatives provide the best balance of trade-offs in terms
of the five balancing criteria, while also considering the statutory preference for treatment as a
principal element in addition to state and community acceptance. SVE operations in areas with
VOCs will reduce concentrations of contamination in the vadose zone and will effectively reduce
the mobility and volume of VOCs remaining onsite.
2.14.5 Preference for Treatment intent
The SVE and excavation components of Alternative 4 will reduce the volume, toxicity, and/or
mobility of contaminants, meeting the statutory preference for treatment as a principal element.
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The soil and vadose zone contaminated with VOCs will be treated to remove the contamination
where possible. Actions to prevent exposure will be required until the sources of VOCs in shallow
groundwater originating in upgradient OUs can be remediated. Relatively immobile contaminants in
surface soils will be removed (e.g., metals and PCBs) to meet future land use designation.
Though, not considered a Principal Threat Waste, elevated VOC levels in soil gas, in portions of
Chemical Plant 2, will be treated, thus satisfying the statutory preference for treatment as a
principal element.
2.14.6 Five-Year Review Requirements
Because remedies (Alternatives 2, 3, and 4) may result in hazardous substance, pollutants, or
contaminants remaining onsite above levels that allow for unrestricted use and unrestricted
exposure, a statutory Five-year review (FYR) will be required. A FYR will be conducted within
five years after initiation of the remedial action, and every five years thereafter, to ensure that the
remedy is, or will be, protective of human health and the environment.
2,15 Documentation of Significant Changes
Following many comments during the public meeting regarding the public review period of the
Proposed Plan, EPA extended the deadline for the public comment period from June 7 to
September 20, 2013.
The Proposed Plan fact sheet incorrectly listed the State of California values for several
compounds for the protection of human health and groundwater from contamination in soils in
the preliminary cleanup level table included in the Proposed Plan. A revised cleanup level table
was included in an updated fact sheet submitted in June 2013.
In July 2014, DTSC issued HHRA Note 3 which includes specific contaminants including lead
in soil. It establishes risk-based soil concentration for a residential use (i.e., unrestricted use)
scenario exposure point concentration, calculated as the 95 percent upper confidence limit on the
arithmetic mean of 80 mg/kg or less, soil lead and an industrial/commercial use 95 percent upper
confidence limit of 320 mg/kg or less soil lead. The lead detections identified during the RI were
re-screened using the updated Note 3 value for lead. Based on this evaluation, two areas were
identified as having lead concentrations greater than 80 mg/kg that were not already included in
a remedial action area. These two areas were numbered L2-R-10 and L2-R-11 and are included
in the summary table in Appendix B and associated figures. The selected remedy for these two
areas is Alternative 4 (Source Removal/Reduction) (Excavation).
Four additional remedial action areas were added to the ROD to address concerns regarding
concentrations of perchlorate in soil that could potentially impact groundwater. These areas were
added with concurrence from DTSC and RWQCB. These areas and their selected remedy are
AW-R-16 (Alternative 3), L5-R-5 (Alternative 4), MA-R-1 (Alternative 4), and CP2-R-12
(Alternative 4). These areas are included in Appendix B and associated figures.
The remedies for two remedial action areas were changed. For AW-R-14, the proposed remedy
was Alternative 3; however, upon further evaluation, it was decided that Alternative 4 would be
more appropriate and more protective.
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I <11 RESPONSIVENESS SUM mi ปh
3,! Stakeholder Issues and EPA Responses
There was significant community response received at the public meeting and provided in
writing during the comment period. Many concerns from the CAG were raised regarding the
limited amount of information provided in the Proposed Plan when compared to the size of
OU-6, the complexity of the area, and the number of remedial action areas to be addressed.
Several concerns regarding the groundwater were included in the CAG's comments, such as how
the groundwater beneath OU-6 is being addressed, how upgradient sources that continue to
contribute to the groundwater contamination beneath OU-6 are being addressed, and how the
groundwater remedies are monitored and enforced. Sitewide and OU-6 groundwater was also
brought up by local water purveyors. The extent of contamination, cleanup levels, and land reuse
concerns were other primary topics brought up during the public comment. The comments and
EPA responses are included in the Responsiveness Summary as Appendix E of this document.
3,2 Technical and Legal Issues
3.2.1 Technical Issues
RSLs were last updated in January 2015. Site cleanup goals selected for this ROD are based on
these new RSLs. The updated RSLs do not adversely affect the selected remedies in this ROD.
However, if new RSLs are issued, the Five-year review will reevaluate cleanup goals to ensure
that the selected remedies are protective of human health and the environment.
3.2.2 Legal Issues
Sacramento County and Aerojet have not completely resolved issues over water replacement.
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Works Cited
Aerojet-General Corporation (Aerojet). 2004. Program Plan Modification Report (Final),
Aerojet Superfund Site, Sacramento County, California. December 25.
Aerojet-General Corporation (Aerojet). 2012. White Paper: Ecological Risk Assessment, Aerojet
Superfund Site, Sacramento County, California. September
American Society for Testing and Materials (ASTM) 2013. Standard Guide for Greener
Cleanups, E2893-13, November
Department of Toxic Substances Control (DTSC). 2011. DTSC Lead Risk Assessment
Spreadsheet: LeadSpread 8 (bloodpb7.xls).
http://www.dtsc.ca.eov/AssessineRisk/leadspread8.cfm
Department of Toxic Substances Control (DTSC). 2014. HERO HHRA Note Number: 3.
DTSC recommended methodology for use of U.S. EPA Regional Screening Levels (RSLs) in the
Human Health Risk Assessment process at hazardous waste sites and permittedfacilities.
DTSC Office of Human and Ecological Risk (HERO). July 14.
Environmental Resources Management (ERM). 2000. Final Site Assessment Report for the
Candidate Carve-Out Lands. Internal Reference Number SRI 0108877. July.
Environmental Resources Management (ERM). 2001. Revision to the Final Site Assessment
Report for the Candidate Carve-Out Lands. May.
Environmental Resources Management (ERM). 2011. Volume II: Final Human Health and
Ecological Risk Assessment for Boundary Operable Unit (OU-6). Aerojet Superfund Site.
Sacramento County, California. September.
ERM-West. 2010. Final Boundary Operable Unit (OU-6) Remedial Investigation and Risk
Assessment, Aerojet Superfund Site. Sacramento County, California. October.
Johnson, P.C., and R.A. Ettinger. 1991. "Heuristic model for predicting the intrusion rate of
contaminant vapors in buildings." Environmental Science & Technology. 25. 1445-1452.
National Oceanic and Atmospheric Administration (NOAA). 1982. Monthly Normals of
Temperature, Precipitation, and Heating and Cooling Degree Days 1951-1980, California.
National Oceanic and Atmospheric Administration (NOAA). 1993. Local Climatological Data
1992, Annual/Monthly Summary.
Regional Water Quality Control Board (RWQCB). 1989. Designated Level Methodology for
Waste Classification and Cleanup Level Determination.
Shaw. 2012. Revised Final Feasibility Study for Boundary Operable Unit (OU6). Aerojet
Superfund Site. Sacramento County, California. September.
Tetra Tech. 2006. Final Site Assessment Report for the Candidate Carve-Out Lands. 2006.
U.S. Environmental Protection Agency (EPA). 1999. A Guide to Preparing Proposed Plans,
Records of Decisions, and Other Remedy Selection Decision Documents.
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U.S. Environmental Protection Agency (EPA). 2000. A Site Manager's Guide to Identifying,
Evaluating and Selecting Institutional Controls at Superfund and RCRA Corrective Action
Cleanups. September.
U.S. Environmental Protection Agency (EPA). 2001. Record of Decision for the Western
Groundwater Operable Unit (OU-3) Aerojet Sacramento Site, Rancho Cordova, California. July
U.S. Environmental Protection Agency (EPA). 2002. Partial Consent Decree, 2002 Stipulation
and Order Modifying PCD.
U.S. Environmental Protection Agency (EPA). 2003. Human Health Toxicity Values in
Superfund Risk Assessments. U.S. Environmental Protection Agency, Office of Solid Waste and
Emergency Response, Washington, DC. OSWER Directive 9285.7-53. December 5, 2003.
Available online at: http://www.epa.eov/oswer/riskassessment/pdf/hhmemo.pdf.
U.S. Environmental Protection Agency (EPA). 2009a. Greener Cleanup Principles.
http://www.epa.eov/oswer/ereenercleanups/principles.html.
U.S. Environmental Protection Agency (EPA). 2009b. Region IX Greener Cleanup Policies.
http://www.epa.eov/reeion09/climatechanee/pdfs/ereener-cleaniips-policy.pdf
U.S. Environmental Protection Agency (EPA). 2010. Superfund Green Remediation Strategy.
September, http://www.epa.eov/siiperfund/ereenremediation/sf-er-strateey.pdf
U. S. Environmental Protection Agency (EPA). 2011. 011-5 Interim ROD for Groundwater and
Final ROD for Soil for the Perimeter Groundwater Operable Unit. February.
U.S. Environmental Protection Agency (EPA). 2012. Perchlorate Exposure Through The Home
Gardening Pathway. Letter to Community Advisory Group. 5 December 2012.
U.S. Environmental Protection Agency (EPA). 2013. Proposed Plan for Boundary Operable
Unit Cleanup. May
U.S. Environmental Protection Agency (EPA). 2015. Region 9 Regional Screening Levels.
January. Available online at: www.epa.eov/reeion9/siiperfund/pre/index.htmh
U.S. Environmental Protection Agency (EPA). 2015. Methodology for Understanding and
Reducing a Project's Environmental Footprint
http://www.cliiin.ore/ereenremediation/methodoloey/index.cfm
Western Regional Climate Center. 2014. Available online at: http://www.wrcc.dri.edu/. Web site
accessed May 15, 2014.
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dix A
ฆ- i -iiinclwater Plume Maps from ฆ ปi Mi ฆ'
-------
10-0022
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1,
I -
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'
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EXPLANATION
4 Perchlorate Isoconcentration Contour in ppb
Aerojet Property Boundary
Perimeter Groundwater Operable Unit Boundary-OU5
Western Groundwater Operable Unit Boundary-OU3
Aerojet Property Boundary
Operable Unit Boundary-OU4
Operable Unit Boundary-OU5
Operable Unit Boundary-OU6
Operable Unit Boundary-OU7
Operable Unit Boundary-OU8
Operable Unit Boundary-OU9
/ <
Zone 3
OU5
\ t
3 US EPA REGION IX
AEROJET OU5
FIGURE 2
Layer A
Perchlorate Iso-Concentration Contour Map
2007-2010
APPENDIX A - OVERLAY
10-0022
-------
-------
0U3
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^ v ~ ป
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EXPLANATION
5 TCE Iso-Concentration Contour in ppb
Aerojet Property Boundary
Perimeter Groundwater Operable Unit Boundary-OU5
Western Groundwater Operable Unit Boundary-OU3
i Aerojet Property Boundary
Operable Unit Boundary-OU4
Operable Unit Boundary-OU5
Operable Unit Boundary-OU6
Operable Unit Boundary-OU7
Operable Unit Boundary-OU8
Operable Unit Boundary-OU9
ib />'
-X x X-
V
J
1
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OU5
\ i
i
US EPA REGION IX
AEROJET OU5
Scale: 1"= 4,000'
i i i
0 2,000 4,000
FIGURE 4
Layer C
TCE Iso-Concentration Contour Map
2007-2010
APPENDIX A - OVERLAY
10-0022
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10-0022
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10-0022
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Appendix II
Sum mi medial Action Areas
-------
Appendix B: Summary of Remedial Action Areas
Contaminants of Concemb
(Maximum Concentrations)
Human Health Risk Summary
Unrestricted Use
Industrial Use
Retained
Area3
Description of
Remedial Action Area
Status of
Contamination
Planned Use
HH COCs
Ecological
COPECs
Protection of
Groundwater COCs
Soil V apor
Soil Vapor
Selected Rationale for
Alternative Action and Selected Remedy
Administration Area East
AE-R-1
This area is located on the west
side of Building 20002, which is a
rocket engine manufacturing
facility.
Soil contamination may
extend beneath Building
20002. Contamination
status is based on samples
from one boring. The
extent of contamination
has not been fully defined.
Commercial
Benzo(a)anthracene
(0.045 mg/kg)
TPH-D (970 mg/kg)
TPH-Mo (2.100 mg/kg)
NA
NA
NA
NA
Alternative 3 -
Containment and
Engineering Controls,
incorporating
Alternative 2 ICs
(Capping)
Action is warranted due to the risks to
groundwater. Because of the
complexity of the area (multiple
underground utility lines and
buildings), capping is the selected
remedy, which will protect human
health and the environment by
providing a protective barrier that,
along with ICs, will mitigate
unacceptable exposures and protect
the cap system.
AE-R-2
This retained area is located
between Buildings 20002 and
20004, and is collocated with
AE-R-4. Both buildings are rocket
engine manufacturing facilities.
Soil contamination may
extend beneath both
buildings. Volume of
contamination is not well
defined. This area
overlaps with AE-R-4.
Commercial
1,1,2,2-PCA (2.0 mg/kg)
Aroclor-1254
(47 mg/kg)
Iron (206,000 mg/kg)
Aroclor-1254
(47 mg/kg)
Iron (206,000 mg/kg)
NA
ILCR = 5E-04
HI = 42
NA
ILCR = 2E-04
HI = 4
Alternative 3 -
Containment and
Engineering Controls,
incorporating
Alternative 2 ICs
(Capping)
Action is warranted due to the risks to
human health (HI >1) and protection
of groundwater. Due to the
complexity of the area (multiple
underground utility lines and
buildings), capping is the selected
remedy, which will protect human
health and the environment by
providing a protective barrier that,
along with ICs, will mitigate
unacceptable exposures and protect
the cap system. The 1,1,2,2-PCA
contamination will be addressed by
the SVE system at AE-SV-R-7.
AE-R-3
The contaminated area is located
along the southwest side of
Building 20004, which is a rocket
engine manufacturing facility.
Soil contamination may
extend beneath building
20004. The lateral extent
of contamination has not
been fully defined.
Commercial
Benzo(a)anthracene
(88.4 mg/kg)
Benzo(a)pyrene
(61.7 mg/kg)
Benzo(b)fluoranthene
(47.5 mg/kg)
Benzo(k)fluoranthene
(55.5 mg/kg
Chrysene (92.8 mg/kg)
Dibenz(a,h)anthracene
(6.44 mg/kg)
Indeno( l,2,3-c,d)pyrene
(20.8 mg/kg)
Benzo(a)anthracene
(88.4 mg/kg)
Benzo(a)pyrene
(61.7 mg/kg)
Benzo(b )fluoranthene
(47.5 mg/kg)
Benzo(k)fluoranthene
(55.5 mg/kg
Chrysene (92.8 mg/kg)
Dibenz(a,h)anthracene
(6.44 mg/kg)
Indeno( 1,2,3-c,d)pyrene
(20.8 mg/kg)
NA
ILCR = 2E-03
HI = 0.5
NA
ILCR = 7E-04
HI = 0.07 (CW)
Alternative 3 -
Containment and
Engineering Controls,
incorporating
Alternative 2 ICs
(Capping)
While the human health risks are
within the risk management range, the
actual source of the contamination is
unknown but is likely related to
activities in the southwest portions of
Building 20004. Because of the
uncertainties associated with the
lateral and vertical extent, this area is
retained for action. The maximum
concentrations may not have been
identified; higher concentrations may
be located beneath the building
foundation. Action is also warranted
because of the risk to groundwater
quality. Due to the complexity of the
area (multiple underground utility
lines and buildings), capping is the
selected remedy, which will protect
human health and the environment by
providing a protective barrier that,
along with ICs, will mitigate
unacceptable exposures and protect
the cap system.
1 OF 16
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Appendix B: Summary of Remedial Action Areas
Retained
Area3
Description of
Remedial Action Area
Status of
Contamination
Planned Use
Contaminants of Concemb
(Maximum Concentrations)
Ecological Protection of
HH COCs COPECs Groundwater COCs
Human Health Risk Summary
Unrestricted Use Industrial Use
Soil Vapor Soil Soil Vapor Soil
Selected
Alternative
Rationale for
Action and Selected Remedy
AE-R-4
The contaminated area is located
outside the western comer of
Building 20004 and the southern
comer of Building 20002.
The lateral and vertical
extents of the PCB
contamination has not
been defined. This area
overlaps with AE-R-2.
Commercial
Aroclor-1254
(47 mg/kg)
Aroclor-1254
(47 mg/kg)
NA
ILCR = 5E-04
HI = 42
NA
ILCR = 2E-04
HI = 4
Alternative 3 -
Containment and
Engineering Controls,
incorporating
Alternative 2 ICs
(Capping)
Action is warranted because of the
risks to human health (HI> 1) and
protection of groundwater. Due to the
complexity of the area (multiple
underground utility lines and
buildings), capping is the selected
remedy, which will protect human
health and the environment by
providing a protective barrier that,
along with ICs, will mitigate
unacceptable exposures and protect
the cap system.
AE-R-5 and
AE-R-6
The area is located between the
northern comer of Building 20019
(former engineering building) and
the western edge of
Building 20004.
The lateral and vertical
extent of contamination
has not been defined, but
likely extends beneath the
buildings. This remedial
area overlaps with
AE-R-7.
Commercial
Aroclor-1254
(11 mg/kg)
Benzo(a)anthracene
(109 mg/kg)
Benzo(a)pyrene
(67 mg/kg)
Benzo(b)fluoranthene
(59.5 mg/kg)
Benzo(k)fluoranthene
(62.6 mg/kg)
Chrysene (110 mg/kg)
Indeno( l,2,3-c,d)pyrene
(21.9 mg/kg)
Aroclor-1254
(11 mg/kg)
Benzo(a)anthracene
(109 mg/kg)
Benzo(a)pyrene
(67 mg/kg)
Benzo(b )fluoranthene
(59.5 mg/kg)
Benzo(k)fluoranthene
(62.6 mg/kg)
Chrysene (110 mg/kg)
Indeno( 1,2,3-c,d)pyrene
(21.9 mg/kg)
NA
ILCR = 2E-03
HI= 10
NA
ILCR = 7E-04
HI = 1
Alternative 3 -
Containment and
Engineering Controls,
incorporating
Alternative 2 ICs
(Capping)
Action is warranted because of the
protection of groundwater. Due to the
complexity of the area (multiple
underground utility lines and
buildings), capping is the selected
remedy, which will protect human
health and the environment by
providing a protective barrier that,
along with ICs, will mitigate
unacceptable exposures and protect
the cap system.
AE-R-7
The area is located between the
northern comer of Building 20019
and the western edge of
Building 20004.
The lateral and vertical
extent of contamination
has not been defined. This
remedial area is collocated
with AE-R-5 and AE-R-6.
Commercial
Naphthalene (1.9 mg/kg)
Aroclor-1254
(11 mg/kg)
TPH-D (9.100 mg/kg)
TPH-Mo
(12.000 mg/kg)
NA
NA
NA
NA
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted because of the
risk to groundwater quality. This area
is relatively accessible for excavation.
If contamination remains in place after
excavation, ICs will be required to
prevent unacceptable exposures.
AE-R-8
This remedial area is located
northeast of the northern comer of
Building 20004.
The lateral and vertical
extent of contamination
has not been defined.
This area overlaps with
AE-SV-R-4.
Commercial
Aroclor-1254
(3.1 mg/kg)
Lead (210 mg/kg)
Aroclor-1254
(3.1 mg/kg)
Lead (210 mg/kg)
NA
ILCR = 4E-05
HI = 3
NA
ILCR = 7E-06
HI = 0.5 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted because of the
protection of groundwater. This area is
relatively accessible for excavation. If
contamination remains in place after
excavation, ICs will be required to
prevent unacceptable exposures.
AE-R-9
This area is located at the
southeast comer of Building 2004
within a drainage inlet.
The extent of
contamination is limited to
the drainage inlet where
the sample was collected.
Commercial
Aroclor-1254
(0.42 mg/kg)
Aroclor-1260
(1.5 mg/kg)
Hexavalent chromium
(4 mg/kg)
Lead (110 mg/kg)
Zinc (1,200 mg/kg)
Dimethyl phthalate
(2.6 mg/kg)
Aroclor-1254
(0.42 mg/kg)
Aroclor-1260
(1.5 mg/kg)
Aroclor-1254
(0.42 mg/kg)
Aroclor-1260
(1.5 mg/kg)
Hexavalent chromium
(4 mg/kg)
Lead (110 mg/kg)
NA
ILCR = 2E-05
HI = 2
NA
ILCR = 7E-06
HI = 0.7 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted due to the
ecological receptors and protection of
groundwater. The sediment in this
area is easily accessible for removal.
The sediment in the drainage inlet will
be removed. If contamination remains
in place after excavation, ICs will be
required to prevent unacceptable
exposures.
2 OF 16
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Appendix B: Summary of Remedial Action Areas
Human Health Risk Summary
Contaminants of Concemb
(Maximum Concentrations) Unrestricted Use Industrial Use
Retained Description of Status of Ecological Protection of Selected Rationale for
Area3 Remedial Action Area Contamination Planned Use HH COCs COPECs Groundwater COCs Soil Vapor Soil Soil Vapor Soil Alternative Action and Selected Remedy
AE-SV-R-l and
AE-SV-R-2
This remedial area is located at the
northwest comer of Building
20002 and extends north along a
drainage channel.
The lateral and vertical
extent of the soil vapor
contamination has not
been defined. This soil
vapor contamination
likely extends beneath
Building 20002.
Commercial
PCE (70.000 (.ig/m3)
Vinyl chloride
(170.000 |ig/m3)
TCE (10.000 (.ig/m3)
Benzene (2.600 (.ig/m3)
ILCR = 2E-03
HI = 3
NA
ILCR = 5E-04
HI = 0.5
NA
Alternative 4 -
Source Removal/
Reduction (SVE)
SVE is the selected remedy for VOCs
in soil vapor that are present at
concentrations that pose an
unacceptable risk from soil vapor
migration into indoor air and/or
present a threat to groundwater
quality. ICs will mitigate unacceptable
exposures and protect the SVE
system.
AE-SV-R-3C
AE-SV-R-3 consists of the area
where a potential residential
human health risk is identified in
ambient air from the VOCs in the
contaminated groundwater.
The extent of
contamination is defined
by the extent of TCE
contaminated groundwater
beneath the site, with an
additional 100-foot buffer
around the area.
Commercial
TCE (12.000 jLig/L)
GW to IA:
ILCR = 3E-03
HI =46
NA
GW to IA:
ILCR = 8E-04
HI =7
NA
Alternative 3 -
Engineering Controls,
incorporating
Alternative 2 ICs
Because the remediation of the
groundwater is ongoing and not yet
complete, the risk of vapor intrusion
from the groundwater is still present.
The selection of ICs and ECs will
mitigate any unacceptable exposure
by restricting property use or to
establish management controls
(e.g.. subslab depressurization. subslab
venting, or an alternate mitigation
system that may prove to have results
equal to or better than those of SSD or
SSV systems to prevent intrusion to
indoor air) that would allow
unrestricted use.
AE-SV-R-4 and
AE-SV-R-5
This remedial area is located at
the northwest comer of
Building 20037, a chemical and
hazardous waste storage building,
and extends along the surface
drainage system associated with
Building 20022.
The lateral and vertical
extent of the soil vapor
contamination has not
been defined. This area
may overlap with AE-R-8.
Commercial
PCE (73.000 (.ig/nr3)
PCE (73.000 (.ig/nr3)
ILCR = 8E-06
HI = 2
NA
ILCR = 2E-05
HI = 0.2
NA
Alternative 4 -
Source Removal/
Reduction (SVE)
Action is warranted in this area due to
the risk to groundwater quality. SVE
is the selected remedy for VOCs in
soil vapor that are present at
concentrations that pose an
unacceptable risk from soil vapor
migration into indoor air or present a
threat to groundwater quality. If
contamination remains in place after
the SVE that does not allow for
unrestricted use. ICs will be required
to prevent unacceptable exposure and
to protect the SVE system.
AE-SV-R-6
This area is located in the southern
portion of Administration Area
West, which includes the rocket
engine manufacturing facilities
associated with Buildings 20002
and 20004.
The lateral and vertical
extent of contamination
has not been defined.
Groundwater has likely
been impacted.
Commercial
TCE (700.000 (.ig/nr3)
NA
NA
NA
NA
Alternative 4 -
Source Removal/
Reduction (SVE)
Action is warranted because of the
risk to groundwater quality. SVE is
the selected remedy for VOCs in soil
vapor that are present at
concentrations that pose an
unacceptable risk from soil vapor
migration into indoor air or present a
threat to groundwater quality. If
contamination remains in place after
the SVE that does not allow for
unrestricted use. ICs will be required
to prevent unacceptable exposure and
to protect the SVE system.
3 OF 16
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Appendix B: Summary of Remedial Action Areas
Human Health Risk Summary
Ui 111.
(Maximum Concentrations)
Unrestricted Use
Industrial Use
Retained
Area3
Description of
Remedial Action Area
Status of
Contamination
Planned Use
HH COCs
Ecological
COPECs
Protection of
Groundwater COCs
Soil V apor
Soil
Soil Vapor
Soil
Selected
Alternative
Rationale for
Action and Selected Remedy
AE-SV-R-7 and
AE-SV-R-8
This area is located along the
southern edge of Building 20002
and south of the southwest comer
of Building 20002.
The lateral and vertical
extent of contamination
has not been defined.
Groundwater has likely
been impacted.
Commercial
1.1.2.2-PCA (2 mg/kg)
TCE (14.000 ng/m3)
PCE (30.000.000 (.ig/m3)
TCE (260.000 ng/m3)
GW to IA:
ILCR = 4E-02
HI =360
NA
GW to IA:
ILCR = 1E-02
HI =130
NA
Alternative 4 -
Source Removal/
Reduction (SVE)
Action is warranted because of the
risk to groundwater quality. SVE is
the selected remedy for VOCs in soil
vapor that are present at
concentrations that pose an
unacceptable risk from soil vapor
migration into indoor air or present a
threat to groundwater quality. The
1.1.2.2-PCA contamination in soil is
associated with AE-R-2 and will be
addressed by the SVE system at AE-
SV-R-7. If contamination remains in
place after the SVE that does not
allow for unrestricted use. ICs will be
required to prevent unacceptable
exposure and to protect the SVE
system.
Administration Area West
AW-R-l.AW-
R-2, and AW-
R-ll
This area is located west of
Building 20009, in area that likely
received surface water runoff from
the Administration Area West.
The lateral and vertical
extent of contamination
has not been defined.
Mixed use
Aroclor-1260
(2.5 mg/kg)
Cadmium
(9.6 mg/kg)
Chromium
(670 mg/kg)
Mercury
(0.24 mg/kg)
Aroclor-1254
(2.5 mg/kg)
Aroclor-1260
(2.5 mg/kg)
Cadmium (9.6 mg/kg)
Chromium (670 mg/kg)
NA
ILCR = 3E-05
HI = 2.5
NA
ILCR = 8E-06
HI = 1 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted in this area due to
the risk to human health (HI>1).
protection of groundwater, the
uncertainties in the lateral and vertical
extent of contamination, and the risks
to ecological receptors. This area is
relatively accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
AW-R-3
The area is located within the
Administration Area West Open
Ditch System.
The lateral extent of
contamination within the
Open Ditch System in this
area has not been defined.
Mixed use
Aroclor-1260
(0.1 mg/kg)
Mercury
(0.23 mg/kg)
Aroclor-1260
(0.1 mg/kg)
Benzo(a)pyrene
(0.014 mg/kg)
Benzo(b&k)fluoranthene
(0.038 mg/kg)
Cadmium (1.7 mg/kg)
Lead (62 mg/kg)
NA
ILCR = 2E-06
HI = 0.2
NA
ILCR = 5E-07
HI = 0.4 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted because of the
risks to human health (lead
concentrations exceed the PTGW
value of 23 mg/kg [most conservative
value for Xerorthents soils]), the risk
to groundwater quality, and the risk to
ecological receptors. This area is
relatively accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
AW-R-4 and
AW-R-5
This area is located near the
southwest comer of
Building 20009. AW-R-4 is
located within a lined culvert
along the southern edge of
Building 20009.
The lateral and vertical
extent of contamination
has not been defined.
Mixed use
Aroclor-1260
(0.17 mg/kg)
Cadmium
(1.1 mg/kg)
Zinc (75 mg/kg)
Aroclor-1260
(0.17 mg/kg)
Aroclor-1260
(0.17 mg/kg
TPH-D (240 mg/kg)
TPH-Mo (730 mg/kg)
NA
ILCR = 3E-06
HI = 0.5
NA
ILCR = 8E-07
HI = 0.3 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted in this area
because of the risk to groundwater
quality, ecological risks, and the
uncertainties in the lateral and vertical
extent of contamination. This area is
relatively accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
Excavation within the culvert will be
limited to the soil and sediment within
the culvert (the liner will not be
removed).
4 OF 16
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Appendix B: Summary of Remedial Action Areas
Human Health Risk Summary
Contaminants of Concemb
(Maximum Concentrations) Unrestricted Use Industrial Use
Retained Description of Status of Ecological Protection of Selected Rationale for
Area3 Remedial Action Area Contamination Planned Use HH COCs COPECs Groundwater COCs Soil Vapor Soil Soil Vapor Soil Alternative Action and Selected Remedy
AW-R-6
This area is located just outside
the northwest comer of
Building 20009. Building 20009
was previously owned by the
U.S. Air Force (USAF) and has
been identified as a manufacturing
building that generated waste
material
The lateral and vertical
extent of contamination
has not been defined. The
contamination may extend
beneath Building 20009.
Mixed use
Nickel (2,090 mg/kg)
Benzo(a)pyrene
(0.089 mg/kg)
Nickel (2.090 mg/kg)
Benzo(a)pyrene
(0.089 mg/kg)
NA
ILCR = 3E-07
HI = 3
NA
ILCR = 3E-07 (CW)
HI = 2 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted in the area
because of the risk to human health
(HI> 1) and protection of groundwater.
This area is relatively accessible for
excavation. If contamination remains
in place after excavation. ICs will be
required to prevent unacceptable
exposures.
AW-R-7 and
AW-R-14
This remedial area is located
within the western side of
Building 20009.
The lateral and vertical
extent of contamination
has not been defined.
Mixed use
Benzo(a)pyrene
(0.52 mg/kg)
Benzo(b&k)fluoranthene
(0.5 mg/kg)
Flexavalent chromium
(720 mg/kg)
Lead (640 mg/kg)
Nickel (1,600 mg/kg)
Benzo(a)pyrene
(0.52 mg/kg)
Benzo(b&k)fluoranthene
(0.5 mg/kg)
Flexavalent chromium
(720 mg/kg)
Lead (640 mg/kg)
Nickel (1.600 mg/kg)
NA
ILCR = 4E-05
HI = 3.3
NA
ILCR = 5E-04 (CW)
HI = 33 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted in this area due to
the risks to human health (HI> 1) and
protection of groundwater. In addition,
lead concentrations exceed the
unrestricted use cleanup level of 80
mg/kg. This area is relatively
accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
AW-R-8. AW-
R-9, AW-R-10,
AW-R-12, and
AW-R-13
This remedial area consists of the
bermed pond area west of
Building 20009 and the area along
the Administration Area West
Open Ditch System.
The lateral and vertical
extent of contamination
has not been defined.
Mixed use
Antimony (49 mg/kg)
Flexavalent chromium
(720 mg/kg)
Lead (640 mg/kg)
Nickel (1,600 mg/kg)
Perchlorate (1.9 mg/kg)
Benzo(a)pyrene
(0.089 mg/kg)
Mercury
(31.1 mg/kg)
Cadmium
(190 mg/kg)
Antimony
(49 mg/kg)
Boron (164 mg/kg)
Chromium
(43.000 mg/kg)
Copper (960 mg/kg)
Manganese
(10.100 mg/kg)
Nickel
(1.600 mg/kg)
Zinc (6.410 mg/kg)
Lead (285 mg/kg)
Molybdenum
(15 mg/kg))
Silver (160 mg/kg)
TPH-D (230 mg/kg)
TPH-Mo (640 mg/kg)
Benzo(a)pyrene
(0.041 mg/kg)
Benzo(b&k)fluoranthene
(0.16 mg/kg)
Perchlorate (1.9 mg/kg)
Cadmium (190 mg/kg)
Chromium
(43.000 mg/kg)
Flexavalent chromium
(720 mg/kg)
Lead (640 mg/kg)
Manganese
(10.100 mg/kg)
Nickel (1.600 mg/kg)
Mercury (31.1 mg/kg)
NA
ILCR = 4E-04
HI = 4
NA
ILCR = 4E-04 (CW)
HI = 29 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted in the area
because of the risk to human health
(HI> 1). the risk to ecological
receptors, and the risks to groundwater
quality. In addition, lead
concentrations exceed the unrestricted
use cleanup level of 80 mg/kg. This
area is relatively accessible for
excavation. If contamination remains
in place after excavation. ICs will be
required to prevent unacceptable
exposures.
AW-R-15
This area is designated as Air
Force Plant 70 and is located
along the west side of Building
20009. PCB soil contamination in
this area was partially excavated
by the Air Force in 2005 to meet
the previous cleanup level of 25
mg/kg.
The extent of the PCB soil
contamination has not
been defined to the current
unrestricted use cleanup
level of 0.089 mg/kg.
Mixed use
Arochlor-1260
(1,060 mg/kg)
Arochlor-1260
(1.060 mg/kg)
NA
ILCR = 2E-05
HI = 2
NA
ILCR = 7E-06
HI = 0.5 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted in this area
because of the risks to human health
(HI> 1) and to groundwater quality.
This area is relatively accessible for
excavation. If contamination remains
in place after excavation. ICs will be
required to prevent unacceptable
exposures.
AW-R-16
This area is located in southern
portion of Administration Area
West, near the former sewage
treatment plant.
The lateral extent of the
contamination has not
been defined. The
contamination in this area
is shallow; perchlorate
concentrations were found
above the cleanup levels
in the upper 5 feet bgs.
Mixed Use
Perchlorate
(0.099 mg/kg)
Perchlorate
(0.099 mg/kg)
NA
HI = 1.7
NA
HI = 1.1
Alternative 4 - Source
Removal/
Reduction (Excavation)
Action is warranted in this area
because of the risks to human health
(HI> 1) and to groundwater quality.
This area is relatively accessible for
excavation. If contamination remains
in place after excavation. ICs will be
required to prevent unacceptable
exposures.
5 OF 16
-------
Appendix B: Summary of Remedial Action Areas
Human Health Risk Summary
Ui 111.
(Maximum Concentrations)
Unrestricted Use
Industrial Use
Retained
Area3
Description of
Remedial Action Area
Status of
Contamination
Planned Use
HH COCs
Ecological
COPECs
Protection of
Groundwater COCs
Soil V apor
Soil
Soil Vapor
Soil
Selected
Alternative
Rationale for
Action and Selected Remedy
AW-SV-R-1C
AW-SV-R-1 consists of the area
where a potential residential
human health risk is identified in
ambient air from the VOCs in the
contaminated groundwater.
The extent of
contamination is defined
by the extent of VOC
contaminated groundwater
beneath the site, with an
additional 100-foot buffer
around the area.
Mixed use
TCE (230 jLig/L)
GW to IA:
ILCR = 2E-05
HI = 0.2
NA
GW to IA:
ILCR = 5E-06
HI = 0.03
NA
Alternative 3 -
Engineering Controls,
incorporating
Alternative 2 ICs
Because the remediation of the
groundwater is ongoing and not yet
complete, the risk of vapor intrusion
from the groundwater is still present.
The selection of ICs and ECs will
mitigate any unacceptable exposure
by restricting property use or to
establish management controls (e.g.,
subslab depressurization, subslab
venting, or an alternate mitigation
system that may prove to have results
equal to or better than those of SSD or
SSV systems to prevent intrusion to
indoor air) that would allow
unrestricted use.
Line 2 Region / Open Space 5
L2-R-1
This remedial area is located just
north of Building 02023 (a
process laboratory).
The lateral and vertical
extent of contamination
has not been defined.
Commercial
mixed use
Perchlorate (0.55 mg/kg)
Perchlorate (0.55 mg/kg)
NA
HI = 9
NA
HI = 6
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted due to the risk to
groundwater quality and to address the
uncertainties in the extent (the
perchlorate is from one soil boring).
This area is relatively accessible for
excavation. If contamination remains
in place after excavation, ICs will be
required to prevent unacceptable
exposures.
L2-R-2 and
L2-R-3
This area is on the southeast side
of Building 02024 (Crawford
Bomb Station), which handled
propellants and discharged
wastewater potential containing
solvents, perchlorate, and
beryllium to the pond through a
concrete lined trough.
The lateral and vertical
extent of contamination
has not been defined.
Contamination may
extend beneath the
building.
Commercial
mixed use
Benzo(a)pyrene
(0.32 mg/kg)
Benzo(b&k)fluoranthene
(0.74 mg/kg)
Perchlorate (0.14 mg/kg)
Benzo(a)pyrene
(0.32 mg/kg)
Benzo(b&k)fluoranthene
(0.74 mg/kg
Perchlorate (0.14 mg/kg)
TPH-D (110 mg/kg)
NA
ILCR= 1E-05
HI = 0.3
NA
ILCR = 4E-06
HI = 0.8 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted because of the
risk to groundwater quality and to
address uncertainties associated with
the lateral and vertical extent of
contamination. The maximum
concentrations may not have been
identified; higher concentrations may
be located beneath the building
foundation. This area is relatively
accessible for excavation. If
contamination remains in place after
excavation, ICs will be required to
prevent unacceptable exposures.
6 OF 16
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Appendix B: Summary of Remedial Action Areas
Human Health Risk Summary
Contaminants of Concemb
(Maximum Concentrations) Unrestricted Use Industrial Use
Retained Description of Status of Ecological Protection of Selected Rationale for
Area3 Remedial Action Area Contamination Planned Use HH COCs COPECs Groundwater COCs Soil Vapor Soil Soil Vapor Soil Alternative Action and Selected Remedy
L2-R-4, L2-R-5,
and L2-R-9
This remedial area is located
around a concrete lined pond and
an unlined pond, which are part of
the former drum and equipment
cleaning area
The lateral and vertical
extent of contamination
has not been defined.
Perchlorate has been
detected in groundwater in
this area.
Commercial
mixed use
Perchlorate (5.1 mg/kg)
Perchlorate (10 mg/kg)
Manganese
(2.200 mg/kg)
Nickel (130 mg/kg)
Thallium (5.61 mg/kg)
Aluminum
(53.000 mg/kg)
NDMA (0.0013 mg/kg)
NA
HI = 85
NA
HI = 57
Alternative 4 -
Source Removal/
Reduction (Excavation
with Soil Flushing and
Air Stripping)
Action is warranted due to the risks to
human health and groundwater quality.
Due to the complexity of these
overlapping sites (L2-R-4. L2-R-5.
L2-R-9. L2-SV-R-2) and the variety
of COCs present, a combination of
excavation with soil flushing and air
stripping is the selected remedy.
The details and order of
implementation of these cleanup
methods will be described during the
RD/RA phase. If contamination
remains in place after source
removal/reduction. The selection of ICs
and ECs will be required to mitigate
any unacceptable exposure by
restricting property use or to establish
management controls (e.g.. subslab
depressurization. subslab venting, or
an alternate mitigation system that may
prove to have results equal to or better
than those of SSD or SSV systems to
prevent intrusion to indoor air) that
would allow unrestricted use.
L2-R-6
This area is located between
Buildings 02090 and 02028 and
likely associated with the septic
tank in this area.
The lateral and vertical
extent of contamination
has not been defined and
may extend beneath the
buildings.
Commercial
mixed use
Perchlorate (0.14 mg/kg)
Perchlorate (0.14 mg/kg)
NA
HI = 2.3
NA
HI = 1.6
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted due to the risk to
human health and groundwater
quality. This area is relatively
accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
L2-R-7 and L2-
R-8
This contaminated area is located
around (and likely beneath)
Building 02020, which has been
identified as an oxidizer grind
station.
The lateral and vertical
extent of contamination
has not been defined and
the contamination may
extend beneath Building
02020.
Commercial
mixed use
Perchlorate (0.29 mg/kg)
Perchlorate (1.7 mg/kg)
NA
HI = 28
NA
HI= 19
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted due to the risk to
groundwater quality. This area is
relatively accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
L2-R-10
This remedial area is located north
of Buildings 02027, 02026, and
02025, along the west side of
Source Area E(m).
The lateral and vertical
extent of the soil
contamination has not
been defined.
Commercial
mixed use
Lead (120 mg/kg)
Lead (120 mg/kg)
NA
ILCR=NA
HI=0.42
NA
ILCR=NA
HI=0.9 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted in this area
because lead concentrations exceeded
the unrestricted use cleanup level of
80 mg/kg. This area is relatively
accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
L2-R-11
This remedial area is located west
of Building 02024.
The lateral and vertical
extent of the soil
contamination has not
been defined.
Commercial
mixed use
Lead (240 mg/kg)
Lead (240 mg/kg)
NA
ILCR=2E-07
HI=0.63
NA
ILCR=5E-08
HI=1.2
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted in this area
because lead concentrations exceeded
the unrestricted use cleanup level of
80 mg/kg. This area is relatively
accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
7 OF 16
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Appendix B: Summary of Remedial Action Areas
Contaminants of Concemb
(Maximum Concentrations)
Human Health Risk Summary
Unrestricted Use
Industrial Use
Retained
Area3
Description of
Remedial Action Area
Status of
Contamination
Planned Use
HH COCs
Ecological
COPECs
Protection of
Groundwater COCs
Soil V apor
Soil Vapor
Selected Rationale for
Alternative Action and Selected Remedy
L2-SV-R-1C
L2-SV-R-1 consists of the area
where a potential residential
human health risk is identified in
ambient air from the VOCs in the
contaminated groundwater.
The extent of
contamination is defined
by the extent of VOC
contaminated groundwater
beneath the site, with an
additional 100-foot buffer
around the area.
Commercial
mixed use
TCE (1.100 jLig/L)
GW to IA:
ILCR=lE-04
HI=0.3
NA
GW to IA:
ILCR=2E-05
HI=0.1
NA
Alternative 3 -
Engineering Controls,
incorporating
Alternative 2 ICs
Action is warranted because this area
covers the area where a residential
human health risk is identified due to
modeled VOC migration from
groundwater to indoor air based on
VOC concentrations detected in
groundwater. Because the remediation
of the groundwater is ongoing and not
yet complete, the risk of vapor
intrusion from the groundwater is still
present. The selection of ICs and ECs
will mitigate any unacceptable
exposure by restricting property use or
to establish management controls
(e.g.. subslab depressurization. subslab
venting, or an alternate mitigation
system that may prove to have results
equal to or better than those of SSD or
SSV systems to prevent intrusion to
indoor air) that would allow
unrestricted use. If additional
characterization demonstrates that
there is no remaining risk to any
receptors above acceptable levels,
then Alternative 2 would apply.
L2-SV-R-2
This remedial area is located in
the western portion of Line 2,
immediately adjacent to the
former location of the
concrete-lined and unlined
sump and ponds comprising
Source Area 28E (a former drum
and equipment cleaning area).
The lateral and vertical
extent of contamination
has not been defined. This
area overlaps with L2-R-
4. L2-R-5, and L2-R-9.
Commercial
mixed use
TCE (10.000.000 ng/m3)
TCE
(10.000.000 (.ig/m3)
PCE
(800.000 ng/m3)
Toluene
(5.900 (.ig/m3)
TCE (10.000.000 ng/m3)
ILCR = 5E-3
HI= 18
NA
ILCR = 1E-3
HI = 2.9
NA
Alternative 4 -
Source Removal/
Reduction (SVE)
Action is warranted due to the risks to
groundwater quality. SVE is the
selected remedy for VOCs in soil
vapor that are present at
concentrations that pose an
unacceptable risk from soil vapor
migration into indoor air under an
unrestricted use scenario or present a
threat to groundwater quality. The
implementation and design of the
remedy would be coordinated with the
design of the remedies for L2-R-4.
L2-R-5. and L2-R-9. If contamination
remains in place after SVE that does
not allow for unrestricted use. ICs will
be required to prevent unacceptable
exposures and to protect the SVE
system.
8 OF 16
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Appendix B: Summary of Remedial Action Areas
Human Health Risk Summary
Ui 111.
(Maximum Concentrations)
Unrestricted Use
Industrial Use
Retained
Area3
Description of
Remedial Action Area
Status of
Contamination
Planned Use
HH COCs
Ecological
COPECs
Protection of
Groundwater COCs
Soil V apor
Soil
Soil Vapor
Soil
Selected
Alternative
Rationale for
Action and Selected Remedy
L2-SV-R-3
This remedial area is located in
the southern portion of the Former
Drum Storage Area.
The lateral and vertical
extent of contamination
has not been defined.
Commercial
mixed use
TCE (160.000 (.ig/m3)
NA
NA
NA
NA
Alternative 4 -
Source Removal/
Reduction (SVE)
Action is warranted due to the risks to
groundwater quality. SVE is the
selected remedy for VOCs in soil
vapor that are present at
concentrations that pose an
unacceptable risk from soil vapor
migration into indoor air under an
unrestricted use scenario or present a
threat to groundwater quality. If
contamination remains in place after
SVE that does not allow for
unrestricted use. ICs will be required
to prevent unacceptable exposures and
to protect the SVE system.
Line 5 North / Open Space 7
L5-R-1
This remedial area is within a
drainage swale in the northeast
comer of the Line 5 North Area
that potentially received surface
water runoff from the area
surrounding Building 05087.
Chemicals that may have been
used or handled at Building 05087
include solid propellant. liner
materials, and solvents.
The lateral extent of
contamination has not
been defined.
Residential use
Benzo(a)pyrene
(0.13 mg/kg)
Cadmium
(4.8 mg/kg)
Di-n-octyl phthalate
(1.2 mg/kg)
Benzo(a)pyrene
(0.13 mg/kg)
Cadmium (4.8 mg/kg)
NA
ILCR = 5E-06
HI = 0.7
NA
ILCR = 1E-06
HI = 0.02 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted due to the risks to
ecological receptors, the uncertainties
in the lateral extent of contamination,
and protection of groundwater.
Further assessment would remove the
uncertainties in the extent of the
contamination and excavation would
eliminate risks to ecological and
human receptors, allowing for the
planned residential use. This area is
relatively accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
L5-R-2
This area is located on the western
comer of Building 05112, which
consists of a test cell and blast
area.
The lateral and vertical
extent of contamination
has not been defined. This
area overlaps with L5-SV-
R-l.
Residential use
Perchlorate (0.52 mg/kg)
Perchlorate (0.52 mg/kg)
NA
HI = 9
NA
HI = 6
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted due to the risks to
groundwater quality. This area is
relatively accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
L5-R-3
This remedial area is located on
the west side of Building 05087
where solid propellant, liner
materials, and solvents may have
been used or handled.
The lateral and vertical
extent of contamination
has not been defined. This
area overlaps with area
L2-SV-R-2.
Residential use
Perchlorate (0.26 mg/kg)
Perchlorate (0.26 mg/kg)
Benzo(b&k)fluoranthene
(0.18 mg/kg)
TPH-D (2.200 mg/kg)
TPH-Mo (5.700 mg/kg)
Perchlorate (0.26 mg/kg)
Cadmium (1.8 mg/kg)
Lead (52 mg/kg)
NA
HI = 4
NA
HI = 3
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted due to the risks to
groundwater quality. This area is
relatively accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
L5-R-4
This remedial area is located on
the east side of Building 05087.
The lateral and vertical
extent of contamination
has not been defined.
Residential use
Perchlorate
(0.077 mg/kg)
Perchlorate
(0.077 mg/kg)
Lead (43 mg/kg)
Cadmium (0.63 mg/kg)
NA
HI = 1.3
NA
HI = 0.9
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted due to the risks to
groundwater quality. This area is
relatively accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
9 OF 16
-------
Appendix B: Summary of Remedial Action Areas
Contaminants of Concemb
(Maximum Concentrations)
Human Health Risk Summary
Unrestricted Use
Industrial Use
Retained
Area3
Description of
Remedial Action Area
Status of
Contamination
Planned Use
HH COCs
Ecological
COPECs
Protection of
Groundwater COCs
Soil V apor
Soil Vapor
Selected Rationale for
Alternative Action and Selected Remedy
L5-R-5
This area is located in the western
portion of the Line 05 area.
The lateral extent of
contamination has not
been defined.
Residential use
Perchlorate
(0.086 mg/kg)
Perchlorate
(0.086 mg/kg)
NA
HI = 1.4
NA
HI = 0.96
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted in this area due to
the protection of groundwater, risk to
human health, and the uncertainly in
lateral extent of the contamination.
Further assessment would remove the
uncertainties in the extent of
contamination and excavation would
eliminate risks to human receptors,
allowing for the planned residential
use. If contamination remains in place
after excavation. ICs will be required
to prevent unacceptable exposures.
L5-SV-R-1
This remedial area is located at
Building 05112, which consists of
a test cell and blast area.
The lateral extent of
contamination has not
been defined.
Residential use
TCE (27.000 ng/m3)
PCE (2.300 ng/m3)
NA
NA
NA
NA
Alternative 4 -
Source Removal/
Reduction (SVE)
Action is warranted due to the risks to
groundwater quality. SVE is the
selected remedy for VOCs in soil
vapor that are present at
concentrations that pose an
unacceptable risk from soil vapor
migration into indoor air under an
unrestricted use scenario or present a
threat to groundwater quality. If
contamination remains in place after
SVE that does not allow for
unrestricted use. ICs will be required
to prevent unacceptable exposures and
protect the SVE system.
L5-SV-R-2
This remedial area is located at a
concrete wash area.
The lateral extent of
contamination has not
been defined.
Residential use
TCE (7.800 ng/m3)
NA
NA
NA
NA
Alternative 4 -
Source Removal/
Reduction (SVE)
Action is warranted due to the risks to
groundwater quality. SVE is the
selected remedy for VOCs in soil
vapor that are present at
concentrations that pose an
unacceptable risk from soil vapor
migration into indoor air under an
unrestricted use scenario or present a
threat to groundwater quality. If
contamination remains in place after
SVE that does not allow for
unrestricted use. ICs will be required
to prevent unacceptable exposures and
protect the SVE system.
10 OF 16
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Appendix B: Summary of Remedial Action Areas
Contaminants of Concemb
(Maximum Concentrations)
Human Health Risk Summary
Unrestricted Use
Industrial Use
Retained
Area3
Description of
Remedial Action Area
Status of
Contamination
Planned Use
HH COCs
Ecological
COPECs
Protection of
Groundwater COCs
Soil V apor
Soil Vapor
Selected Rationale for
Alternative Action and Selected Remedy
L5-SV-R-3C
This remedial area covers the area
where a residential human health
risk is identified due to modeled
VOC migration from groundwater
to indoor air based on VOC
concentrations detected in
groundwater.
The extent of
contamination is defined
by the extent of VOC
contaminated groundwater
beneath the site, with an
additional 100-foot buffer
around the area.
Residential use
TCE (42 jLig/L)
GW to IA:
(TCE)
ILCR=4E-05
HI=0.2
NA
GW to IA:
(TCE)
ILCR=2E-06
HI=0.004
NA
Alternative 3 -
Engineering Controls,
incorporating
Alternative 2 ICs
Action is warranted because this area
covers the area where a residential
human health risk is identified due to
modeled VOC migration from
groundwater to indoor air based on
VOC concentrations detected in
groundwater. Because the remediation
of the groundwater is ongoing and not
yet complete, the risk of vapor
intrusion from the groundwater is still
present. The selection of ICs and ECs
will mitigate any unacceptable
exposure by restricting property use or
to establish management controls
(e.g., subslab depressurization, subslab
venting, or an alternate mitigation
system that may prove to have results
equal to or better than those of SSD or
SSV systems to prevent intrusion to
indoor air) that would allow
unrestricted use. If additional
characterization demonstrates that
there is no remaining risk to any
receptors above acceptable levels,
then Alternative 2 would apply.
Buffalo Creek
BC-R-1
This area consists of Upper
Buffalo Creek, north of Line 5
North and was identified as a
remedial area to address
ecological risks.
The lateral and vertical
extent of contamination
has not been defined.
Contamination likely
extends upstream of the
OU-6 boundary.
Open space
drainage
Aroclor-1254
(1.1 mg/kg)
Aroclor-1254
(1.1 mg/kg)
Lead (721 mg/kg)
Mercury (0.31
mg/kg)
Silver (77.2 mg/kg)
Zinc (174 mg/kg)
Aroclor-1254
(1.1 mg/kg)
Lead (721 mg/kg)
NA
ILCR= 1E-06
HI = 0.5
NA
ILCR = 4E-06
HI = 4 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted due to the risks
associated with ecological receptors,
the uncertainties in the extent of
contamination of Aroclor-1260, and
protection of groundwater. The extent
of Aroclor-1260 has not been defined
and higher concentrations of Aroclor-
1260 may be present and would
therefore require remediation. This
area is relatively accessible for
excavation. If contamination remains
in place after excavation, ICs will be
required to prevent unacceptable
exposures.
11 OF 16
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Appendix B: Summary of Remedial Action Areas
Human Health Risk Summary
Ui 111.
(Maximum Concentrations)
Unrestricted Use
Industrial Use
Retained
Area3
Description of
Remedial Action Area
Status of
Contamination
Planned Use
HH COCs
Ecological
COPECs
Protection of
Groundwater COCs
Soil V apor
Soil
Soil Vapor
Soil
Selected
Alternative
Rationale for
Action and Selected Remedy
BC-R-2
This area consists of the Buffalo
Creek cutoff and was identified as
a remedial area to address
ecological risks.
The lateral and vertical
extent of contamination
has not been defined.
Open space
drainage
Aroclor-1254
(0.360 mg/kg)
Aroclor-1254
(0.36 mg/kg)
Chromium
(905 mg/kg)
Lead (455 mg/kg)
Mercury
(0.28 mg/kg)
Nickel (511 mg/kg)
Silver (35 mg/kg)
Zinc (196 mg/kg)
Aroclor-1254
(0.36 mg/kg)
Chromium (905 mg/kg)
Lead (455 mg/kg)
Nickel (511 mg/kg)
NA
ILCR = 2E-06
HI = 0.2
NA
ILCR = 7E-07
HI = 2 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted due to the risks
associated with ecological receptors,
the uncertainties in the extent of
contamination of Aroclor-1260, and
protection of groundwater. The extent
of Aroclor-1260 has not been defined
and higher concentrations of Aroclor-
1260 may be present and would
therefore require remediation. This
area is relatively accessible for
excavation. If contamination remains
in place after excavation, ICs will be
required to prevent unacceptable
exposures.
West Lakes / Open Space 6
WL-R-1
This area is located in Open Space
6, in the eastern portion of Cell 1
near the outlet gate.
The lateral and vertical
extent of contamination
has not been defined.
Open space
Perchlorate (9 mg/kg)
Perchlorate (9 mg/kg)
NA
HI = 150
NA
HI = 100
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted due to the risks to
groundwater quality. This area is
relatively accessible for excavation. If
contamination remains in place after
excavation, ICs will be required to
prevent unacceptable exposures.
Magazine Area / Open Space 3
MA-R-1
This area is located in the
northwestern portion of the
Magazine Area (soil boring A48-
ST13-SB01).
The lateral and vertical
extent of contamination
has not been defined.
Not currently
planned
Perchlorate (0.33 mg/kg)
Perchlorate (0.33 mg/kg)
NA
HI = 5.5
NA
HI = 3.6
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted due to the risks to
human health and groundwater
quality. This area is relatively
accessible for excavation. If
contamination remains in place after
excavation, ICs will be required to
prevent unacceptable exposures.
MA-SV-R-1C
This remedial area covers the area
where a residential human health
risk is identified due to modeled
VOC migration from groundwater
to indoor air based on VOC
concentrations detected in
groundwater.
The extent of
contamination is defined
by the extent of VOC
contaminated groundwater
beneath the site, with an
additional 100-foot buffer
around the area.
Not currently
planned
TCE (410 jLig/L)
GW to IA:
ILCR=6E-05
HI=0.2
NA
GW to IA:
ILCR=lE-05
HI=0.04
NA
Alternative 2 -
Institutional Controls
Because the remediation of the
groundwater is ongoing and not yet
complete, the risk of vapor intrusion
from the groundwater is still present.
The selection of ICs will mitigate any
unacceptable exposure by restricting
property use. If the land use plan
changes, the selected alternative may
need to be revisited.
12 OF 16
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Appendix B: Summary of Remedial Action Areas
Contaminants of Concemb
(Maximum Concentrations)
Human Health Risk Summary
Unrestricted Use
Industrial Use
Retained
Area3
Description of
Remedial Action Area
Status of
Contamination
Planned Use
HH COCs
Ecological
COPECs
Protection of
Groundwater COCs
Soil V apor
Soil Vapor
Selected Rationale for
Alternative Action and Selected Remedy
Chemical Plant 2 / Open Spaces 1, 2, and 4
CP2-R-1. CP2-
R-8, CP2-R-9,
CP2-R-10, and
CP2-R-11
This area consists of a drainage
ditch located in the western
portion of the Chemical Plant 2
area, areas around Buildings
15004. 15011. 15008. 15010. and
encompasses various facilities in
proximity to Building 15008.
The lateral and vertical
extent of contamination
has not been defined.
Not currently
planned
Aroclor-1248
(120 mg/kg)
Aroclor-1254
(1.9 mg/kg)
Lead (295 mg/kg)
Antimony
(1.1 mg/kg)
Nickel (77 mg/kg)
Selenium
(1.2 mg/kg)
4.4'-DDD
(2.3 mg/kg)
4.4'-DDE
(0.042 mg/kg)
4.4'-DDT
(1.2 mg/kg)
Aroclor-1248
(120 mg/kg)
Aroclor-1254
(0.48 mg/kg)
d-BHC (0.51 mg/kg)
Endrin (0.22 mg/kg)
Prowl (49 mg/kg)
Phenol (14 mg/kg)
Barium
(4.620 mg/kg)
Boron (225 mg/kg)
Cadmium (1 mg/kg)
Lead (295 mg/kg)
Zinc (540 mg/kg)
Aroclor-1248
(120 mg/kg)
Aroclor-1254
(1.9 mg/kg)
Barium (4.620 mg/kg)
Boron (225 mg/kg)
Cadmium (1 mg/kg)
4.4'-DDD (2.3 mg/kg)
4.4'-DDT (1.2 mg/kg)
d-BHC (0.51 mg/kg)
Lead (295 mg/kg)
Nickel (77 mg/kg)
Phenol (14 mg/kg)
NA
ILCR=lE-03
HI=110
NA
ILCR=4E-04
HI=28 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted due to the risk to
human health (HI> 1 and lead
concentrations greater than the
cleanup level of 80 mg/kg). the risks
to ecological receptors, and protection
of groundwater. This area is relatively
accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
CP2-R-2, CP2-
R-3, CP2-R-4,
CP2-R-5. and
CP2-R-6
This area is located in the northern
portion of Chemical Plant 2 in a
low-lying area that likely received
runoff from the Chemical Plant 2
area.
The lateral and vertical
extent of contamination
has not been defined.
Not currently
planned
Aroclor-1254
(2.8 mg/kg)
Aroclor-1248
(0.54 mg/kg)
4.4'-DDE
(0.0069 mg/kg)
4.4'-DDT
(0.013 mg/kg)
Endrin
(0.063 mg/kg)
Phenanthrene
(0.43 mg/kg)
BEHP( 1.3 mg/kg)
Dieldrin
(0.0054 mg/kg)
Endrin aldehyde
(0.014 mg/kg)
Aroclor-1254
(2.8 mg/kg)
Chromium
(114 mg/kg)
Copper (71 mg/kg)
Nickel (94 mg/kg)
Aroclor-1254
(2.8 mg/kg)
Aroclor-1248
(0.54 mg/kg)
Dieldrin (0.0054 mg/kg)
Nickel (94 mg/kg)
NA
ILCR = 3E-05
HI = 2.5
NA
ILCR = 9E-06
HI = 0.7 (CW)
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted due to the
uncertainties in the extent of
contamination of Aroclor. risk to
ecological receptors, and protection of
groundwater. This area is relatively
accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
13 OF 16
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Appendix B: Summary of Remedial Action Areas
Human Health Risk Summary
Contaminants of Concemb
(Maximum Concentrations) Unrestricted Use Industrial Use
Retained Description of Status of Ecological Protection of Selected Rationale for
Area3 Remedial Action Area Contamination Planned Use HH COCs COPECs Groundwater COCs Soil Vapor Soil Soil Vapor Soil Alternative Action and Selected Remedy
CP2-R-7
This remedial area is located in
the northern most section of
Chemical Plant 2.
The lateral and vertical
extent of contamination
has not been defined.
Not currently
planned
Prowl (0.034 mg/kg)
Aroclor-1254
(0.16 mg/kg)
Aroclor-1254
(0.16 mg/kg)
NA
ILCR = 3E-05
HI = 0.2
NA
ILCR = 3E-05
HI = 0.04
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted due to the risk to
ecological receptors, the uncertainties
in the lateral and vertical extent of
contamination, and protection of
groundwater. The data for this
retained action area is from one
boring. This area is relatively
accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
CP2-R-12
This area is located within Source
Area 59F. in the holding basin
area.
The extent of
contamination has not
been defined.
Not currently
planned
Perchlorate
(0.095 mg/kg)
Perchlorate
(0.095 mg/kg)
NA
HI = 1.6
NA
HI = 1
Alternative 4 -
Source Removal/
Reduction (Excavation)
Action is warranted in this area due to
the risk to groundwater. This area is
relatively accessible for excavation. If
contamination remains in place after
excavation. ICs will be required to
prevent unacceptable exposures.
CP2-SV-R-1
and CP2-SV-R-
2
This remedial area is located
around the holding basins in
Source Area 59F. the Chemical
Plant 2 deep well injection
headworks. and associated area.
The lateral and vertical
extent of contamination
has not been defined.
Not currently
planned
1,2-Dichloroethane
(310.000 (.ig/m3)
Vinyl chloride
(830 (.ig/m3)
Chloroform
(120.000 ng/m3)
ILCR = 4E-02
HI =1300
NA
ILCR = 1E-04
HI = 200
NA
Alternative 4 -
Source Removal/
Reduction (SVE)
Action is warranted in this area due to
the risk to human health (HI> 1). SVE
is the selected remedy for VOCs in
soil vapor that are present at
concentrations that pose an
unacceptable risk from soil vapor
migration into indoor air under an
unrestricted use scenario or present a
threat to groundwater quality. If
contamination remains in place after
SVE that does not allow for
unrestricted use. ICs will be required
to prevent unacceptable exposures and
to protect the SVE system.
CP2-SV-R-3
This area is located southeast of
the rail road tracks, along a
potential discharge line that was
connected to the Former Stouffer
Chemical Plant.
The lateral and vertical
extent of contamination
has not been defined.
Contamination is present
beneath the building
foundation. This
contamination likely
overlaps with the soil
vapor contamination at
CP2-SV-R-4.
Not currently
planned
1.2-Dichloroethane
(300.000 ng/m3)
ILCR = 2E-03
HI = 82
NA
ILCR = 6E-04
HI = 13
NA
Alternative 4 -
Source Removal/
Reduction (SVE)
Action is warranted in this area due to
the risk to human health (HI>1). SVE
is the selected remedy for VOCs in
soil vapor that are present at
concentrations that pose an
unacceptable risk from soil vapor
migration into indoor air under an
unrestricted use scenario or present a
threat to groundwater quality. If
contamination remains in place after
SVE that does not allow for
unrestricted use. ICs will be required
to prevent unacceptable exposures and
to protect the SVE system.
14 OF 16
-------
Appendix B: Summary of Remedial Action Areas
Human Health Risk Summary
Contaminants of Concemb
(Maximum Concentrations) Unrestricted Use Industrial Use
Retained Description of Status of Ecological Protection of Selected Rationale for
Area3 Remedial Action Area Contamination Planned Use HH COCs COPECs Groundwater COCs Soil Vapor Soil Soil Vapor Soil Alternative Action and Selected Remedy
CP2-SV-R-4
This area is located south of
CP2-SV-R-3, at the southeastern
comer of the Former Stouffer
Chemical Plant.
The lateral and vertical
extent of contamination
has not been defined.
Contamination is present
beneath the building.
This contamination likely
overlaps with the soil
vapor contamination at
CP2-SV-R-3.
Not currently
planned
1,2-Dichloroethane
(300.000 ng/m3)
ILCR = 3E-04
HI= 10
NA
ILCR = 7E-05
HI = 2
NA
Alternative 4 -
Source Removal/
Reduction (SVE)
Action is warranted in this area due to
the risk to human health (HI>1). SVE
is the selected remedy for VOCs in
soil vapor that are present at
concentrations that pose an
unacceptable risk from soil vapor
migration into indoor air under an
unrestricted use scenario or present a
threat to groundwater quality. If
contamination remains in place after
SVE that does not allow for
unrestricted use. ICs will be required
to prevent unacceptable exposures and
to protect the SVE system.
CP2-SV-R-5
This remedial area is located
along the eastern portion of the
Chemical Plant 2 area.
The lateral and vertical
extent of contamination
has not been defined.
Not currently
planned
1,2-Dichloroethane
(12.000 (.ig/m3)
ILCR= 1E-04
HI =3
NA
ILCR = 3E-08
HI = 0.5
NA
Alternative 4 -
Source Removal/
Reduction (SVE)
Action is warranted in this area due to
the risk to human health (HI>1) and
the uncertainties in the extent of
contamination. SVE is the selected
remedy for VOCs in soil vapor that
are present at concentrations that pose
an unacceptable risk from soil vapor
migration into indoor air under an
unrestricted use scenario. If
contamination remains in place after
SVE that does not allow for
unrestricted use. ICs will be required
to prevent unacceptable exposures
and/or to protect the SVE system.
CP2-SV-R-6C
This remedial area covers the area
where a residential human health
risk is identified due to modeled
VOC migration from groundwater
to indoor air based on VOC
concentrations detected in
groundwater.
The extent of
contamination is defined
by the extent of VOC
contaminated groundwater
beneath the site, with an
additional 100-foot buffer
around the area.
Not currently
planned
TCE (1.800 jLig/L)
GW to IA:
ILCR=lE-04
HI=2
NA
GW to IA:
ILCR=3E-05
HI=0.6
NA
Alternative 2 -
Institutional Controls
Because the remediation of the
groundwater is ongoing and not yet
complete, the risk of vapor intrusion
from the groundwater is still present.
The selection of ICs will mitigate any
unacceptable exposure by restricting
property use. If the land use plan
changes, the selected alternative may
need to be revisited.
Dredge Pit and Eastern Basin
DPEB-R-1
This remedial area is located in
the Dredge Pit, south of Burma
Road and west of the Eastern
Basin. The Dredge pit is roughly 1
acre in size, approximately 40 feet
bgs at its deepest point, and has an
estimated capacity of roughly
6,000,000 gallons.
The contaminated soil is
in an excavated
depression.
Not currently
planned
Mercury (42 mg/kg)
Prowl (17.000 mg/kg)
Boron (656 mg/kg)
Cadmium
(0.91 mg/kg)
Mercury (42 mg/kg)
Molybdenum
(0.95 mg/kg)
Nickel (856 mg/kg)
Thallium
(6.7 mg/kg)
Zinc (116 mg/kg)
DnBP (7.52 mg/kg)
Prowl
(17.000 mg/kg)
Boron (656 mg/kg)
Cadmium (0.91 mg/kg)
Mercury (42 mg/kg)
Nickel (856 mg/kg)
Prowl (17.000 mg/kg)
Thallium (6.7 mg/kg)
NA
ILCR = 7E-07
HI = 1.5
NA
ILCR = 2E-07
HI = 0.08 (CW)
Alternative 3 -
Containment and
Engineering (Backfilling)
Action is warranted in this area due to
the risk to ecological receptors and
protection of groundwater. Backfilling
this area is the selected remedy.
The area will be backfilled with a
minimum of 10 feet of clean soil. This
will eliminate the exposure pathway
for human and ecological receptors.
The IC component will protect the
backfill remedy and address future
land uses.
15 OF 16
-------
Appendix B: Summary of Remedial Action Areas
i i kii t.j |yi i ii >i ii ft- jtf f nn
Human Health Risk Summary
(Maximum Concentrations)
Unrestricted Use
Industrial Use
Retained
Area3
Description of
Remedial Action Area
Status of
Contamination
Planned Use
HH COCs
Ecological
COPECs
Protection of
Groundwater COCs
Soil V apor
Soil
Soil Vapor
Soil
Selected
Alternative
Rationale for
Action and Selected Remedy
DPEB-SV-R-1C
This remedial area covers the area
where a residential human health
risk is identified due to modeled
VOC migration from groundwater
to indoor air based on VOC
concentrations detected in
groundwater.
The extent of
contamination is defined
by the extent of VOC
contaminated groundwater
beneath the site, with an
additional 100-foot buffer
around the area.
Not currently
planned
TCE (1.800 jLig/L)
Boron (656 mg/kg)
Cadmium (0.91 mg/kg)
Mercury (42 mg/kg)
Nickel (856 mg/kg)
Prowl (17,000 mg/kg)
Thallium (6.7 mg/kg)
GW to IA:
ILCR=3E-06
HI=0.02
NA
GW to IA:
ILCR=7E-07
HI=0.007
NA
Alternative 2 -
Institutional Controls
Because the remediation of the
groundwater is ongoing and not yet
complete, the risk of vapor intrusion
from the groundwater is still present.
The selection of ICs will mitigate any
unacceptable exposure by restricting
property use. If the land use plan
changes, the selected alternative may
need to be revisited.
Notes:
a Some remedial action areas were combined because the areas are located adjacent to each other, they overlap each other, and/or they have the same remedial action planned. Combining areas allows for all COCs in the areas to be addressed and helps to facilitate the remedial design.
b For each contaminant identified as a COC for an exposure pathway (risk to human health, ecological receptors, or groundwater), each COC will be evaluated against cleanup levels for all three pathways, where applicable, during the design and implementation of remedial action and to determine if the action is complete.
See Section 2.8 for more details.
c These remedial action areas for soil vapor were identified as an area to be addressed because they overlie a groundwater plume. See Section 2.8 for more details on how these areas were identified.
= No COCs were identified that posed a risk for this pathway.
Hg/L = micrograms per liter
Hg/nr1 = micrograms per meter cubed
AE = Administration East
AW = Administration West
BC = Buffalo Creek
COC = contaminant of concern
COPEC = contaminant of potential ecological concern
CP2 = Chemical Plant 2
CW = construction worker
DPEB = Dredge Pit/Eastern Basin
EC = engineering control
GW to IA = soil vapor from groundwater contamination to indoor air
HH = human health
HI = hazard index
IC = institutional control
ILCR = incremental lifetime cancer risk
L2 = Line 2
L5 = Line 5
mg/kg = milligram per kilogram
NA = not applicable
RD = remedial design
SVE = soil vapor extraction
VOC = volatile organic compound
WL = West Lakes
16 OF 16
-------
|'pencil , 1
Administrati I u hi-! Index
-------
Appendix C: Administration Record Index
Doc ID
Doc Date
Title
Author
Addressee
OU
Pgs
95601
7/20/2001
Record of decision (ROD), western gw OU
(OU-3), w/app A (response summary)
Keith Takata / EPA, Region IX
231
1137732
6/20/2003
Article: Uptake of perchlorate in terrestrial plants
(Ecotoxicology and Environmental Safety, v58
(2004) pp. 44-49)
Lu Yu / Institute of Environmental and
Human Health
6
6
2069877
4/11/2005
Ltr: Status and path forward for removal of PCB
impacted soil at former Air Force Plant 70 -
plans for continued remedial construction and
site closure, w/attchs
Randal Rose / CH2M HILL, Inc.
Charles Berrey / EPA, Region IX
6
7
2069873
4/14/2005
Email: Provisional approval of amended work
plan for closure of AFP 70 (former Air Force
Plant 70), w/history
Charles Berrey / EPA, Region IX
Randal Rose / CH2M HILL, Inc.
6
1
2069861
5/10/2005
Ltr: Response to agency comments on 3/5/05
memo, Background metals response and
recommendations
Cindy Caulk / Aerojet General Corp
Charles Berrey / EPA, Region IX
Ed Cargile / Cal-EPA, DTSC
Alexander MacDonald / CA RWQCB,
Central Valley Region
05
06
07
08
09
3
2085609
6/1/2005
Field sampling plan for validation of Johnson
and Ettinger model, w/TL to C. Berrey, et al. fr
C. Caulk 6/27/05
Aerojet General Corp
04
05
06
07
08
09
27
2069878
6/13/2005
Email: Chemical plant 2 proposed sampling
locations and rationale, w/attchs (Chem Plant 2
proposed Figs and Chem Plant 2 Sample Design
Tables)
Chris Fennessy / Aerojet General Corp
Charles Berrey / EPA, Region IX
Ed Cargile / Cal-EPA, DTSC
Alexander MacDonald / CA RWQCB,
Central Valley Region
6
27
2239152
6/17/2005
Final RI/FS workplan - source area OUs,
updated through 11/4/05 (oversize map only)
Aerojet General Corp
Geosyntec Consultants, Inc.
Tetra Tech E M, Inc.
CA RWQCB, Central Valley Region
EPA, Region IX
Cal-EPA, DTSC
04
06
07
08
09
2
1 OF 7
-------
Appendix C: Administration Record Index
Doc ID
Doc Date
Title
Author
Addressee
OU
Pgs
2244751
6/17/2005
Final RI/FS workplan - source area OUs,
updated through 11/4/05, w/Apps A-D and TL to
C Berrey, et al. fr C Caulk, w/o oversize map
Tetra Tech E M, Inc.
Geosyntec Consultants, Inc.
Aerojet General Corp
Cal-EPA, DTSC
EPA, Region IX
CA RWQCB, Central Valley Region
04
06
07
08
09
295
2085604
7/1/2005
Workplan to determine background metals in
surface soils at site main plant, w/TL to
C Berrey, et al. fr C Caulk 7/22/05
Robert Borch / Geosyntec Consultants, Inc.
Scott Neville / Aerojet General Corp,
Environmental Operations
05
06
07
08
09
11
2085601
7/21/2005
Ltr: Comments on and provisional approval of
final RI/FS work plan for source area OUs
Charles Berrey / EPA, Region IX
Cindy Caulk / Aerojet General Corp
04
06
07
08
09
4
2244752
7/21/2005
Ltr: Comments on Final RI/FS workplan -
source area OUs
Charles Berrey / EPA, Region IX
Cindy Caulk / Aerojet General Corp
04
06
07
08
09
4
2119562
8/1/2005
Removal action rpt for former Air Force Plant 70
at Bldg 20-009, revision 0, w/Apps A-I, Apps
J2 O, TL to C Berrey fr D Weir 8/9/05 and sticky
note
CH2M HILL, Inc.
U.S. Air Force, Center for
Environmental Excellence
6
485
2119563
8/1/2005
Appendix J-l, analytical results - raw data
(Removal action rpt for former Air Force Plant
70 at Bldg 20-009)
CH2M HILL, Inc.
U.S. Air Force, Center for
Environmental Excellence
6
828
2119566
8/23/2005
Ltr: Response to Removal action rpt for former
Air Force Plant 70 at Bldg 20-009 - discusses
remaining requirements
Charles Berrey / EPA, Region IX
Cindy Caulk / Aerojet General Corp
Corey Lam / US Air Force,
Aeronautical Systems Center
6
2
2119564
9/20/2005
Memo: Building 20-009 remediation area survey
results, w/attchs
Corey Lam / US Air Force, Aeronautical
Systems Center
Cindy Caulk / Aerojet General Corp
6
10
2 OF 7
-------
Appendix C: Administration Record Index
Doc ID
Doc Date
Title
Author
Addressee
OU
Pgs
2096937
7/1/2006
Background metals in xerorthents and
Redding-Coming-Red Bluff surface soils at site
main plant, w/TL to P McDaniel, et al. fr C
Caulk 7/26/06 (compact disc only - appendices)
Ray Bienert / Tetra Tech E M, Inc.
Robert Borch / Geosyntec Consultants, Inc.
Scott Neville / Aerojet General Corp,
Environmental Operations
Aerojet General Corp
05
06
07
08
09
1
2107833
7/1/2006
Background metals in xerorthents and
Redding-Coming-Red Bluff surface soils at site
main plant, w/TL to P McDaniel, et al. fr C
Caulk 7/26/06, w/o compact disc
(Appendices A-C)
Ray Bienert / Tetra Tech E M, Inc.
Robert Borch / Geosyntec Consultants, Inc.
Scott Neville / Aerojet General Corp,
Environmental Operations
Aerojet General Corp
05
06
07
08
09
83
2140614
7/1/2006
Compact Disc: Background metals in xerorthents
and Redding-Coming-Red Bluff surface soils at
site main plant (Adobe pdf format)
Aerojet General Corp, Environmental
Remediation Department
01
05
06
08
09
1
2140617
7/31/2006
Compact Disc: Final RI/FS field sampling plan
for boundary OU (complete except Appendix G)
(Adobe pdf format)
Aerojet General Corp
Geosyntec Consultants, Inc.
Tetra Tech E M, Inc.
6
1
2140618
7/31/2006
Compact Disc: Final RI/FS field sampling plan
for boundary OU, figures only (Adobe pdf
format)
Tetra Tech E M, Inc.
Aerojet General Corp
Geosyntec Consultants, Inc.
6
1
2200448
7/31/2006
Final RI/FS field sampling plan for boundary
OU, vl of 2, w/TL to P McDaniel, et al. fr
C Caulk 8/8/06 and sticky note
Tetra Tech E M, Inc.
Geosyntec Consultants, Inc.
Aerojet General Corp
6
754
2200449
7/31/2006
Final RI/FS field sampling plan for boundary
OU, v2 of 2 (Appendices A-G)
Geosyntec Consultants, Inc.
Tetra Tech E M, Inc.
Aerojet General Corp
6
1,006
3 OF 7
-------
Appendix C: Administration Record Index
Doc ID Doc Date Title Author Addressee OU Pgs
1129056
8/11/2006
Final RI/FS QAPP addendum for source area
OUs
Tetra Tech E M, Inc.
Geosyntec Consultants, Inc.
Aerojet General Corp
Cal-EPA, DTSC
EPA, Region IX
CA RWQCB, Central Valley Region
04
06
07
08
09
93
2140585
8/11/2006
Compact Disc: Final RI/FS QAPP addendum for
source area OUs (Adobe pdf format)
Geosyntec Consultants, Inc.
Tetra Tech E M, Inc.
Aerojet General Corp
01
04
06
07
08
09
1
2141577
9/25/2006
Final white paper - ecological risk assessment,
w/appendices and TL to N Black and
J M Eichelberger fr C Caulk
Aerojet General Corp
04
06
07
08
09
47
2244750
7/20/2007
Final RI/FS QAPP addendum for source area
OUs - replacement pages
Tetra Tech E M, Inc.
Aerojet General Corp
Geosyntec Consultants, Inc.
EPA, Region IX
Cal-EPA, DTSC
CA RWQCB, Central Valley Region
04
06
07
08
09
19
2185589
7/22/2008
Ltr: Request for extension on submittal date for
draft RI/FS for Boundary OU, w/attch
Cindy Caulk / Aerojet General Corp
Gary Riley / CA RWQCB, San
Francisco Bay Region
Ed Cargile / Cal-EPA, DTSC
Alexander MacDonald / CA RWQCB,
Central Valley Region
6
3
2246152
9/29/2010
Ltr: Approval of removal action proposal -
Buffalo Creek vegetation and sediment near
ARGET discharge
Gary Riley / EPA, Region IX
Cindy Caulk / Aerojet General Corp
6
2
1133067
10/28/2010
Boundary OU RI/FS rpt, v 2 - final human health
and ecological risk assessment for Boundary OU
(OU-6), w/o Apps A-L
E R M-West, Inc.
Aerojet General Corp
6
2,200
4 OF 7
-------
Appendix C: Administration Record Index
Doc ID
Doc Date
Title
Author
Addressee
OU
Pgs
1133068
10/28/2010
Boundary OU RI/FS rpt, v 1 - final RI rpt for
Boundary area OU (OU-6), w/o Apps A-N
E R M-West, Inc.
Central Valley Environmental, Inc.
Aerojet General Corp
6
1,117
1137728
1/5/2011
Ltr: Comments on final boundary OU-6 RI and
risk assessment, w/attch
Allen Tsao / NONE
Gary Riley / EPA, Region IX
Alexander MacDonald / CA RWQCB,
Central Valley Region
Ed Cargile / Cal-EPA, DTSC
6
6
2246168
2/3/2011
Ltr: Buffalo Creek soil and vegetation removal
rpt, w/o compact disc (Attchs A-C)
Chris Fennessy / Aerojet General Corp
Alexander MacDonald / CA RWQCB,
Central Valley Region
Gary Riley / CA RWQCB, San
Francisco Bay Region
Ed Cargile / Cal-EPA, DTSC
6
6
2259423
2/3/2011
Ltr: Buffalo Creek soil and vegetation removal
rpt (compact disc only)
Chris Fennessy / Aerojet General Corp
Alexander MacDonald / CA RWQCB,
Central Valley Region
Ed Cargile / Cal-EPA, DTSC
Gary Riley / CA RWQCB, San
Francisco Bay Region
6
1
1125069
2/15/2011
Interim record of decision (ROD) for
groundwater and final record of decision (ROD)
for soil for perimeter groundwater operable unit,
OU 5, w/Apps A-D
EPA, Region IX
199
1133069
9/1/2011
Boundary OU RI/FS rpt, v 3 - FS rpt for
Boundary area OU (OU-6), w/Apps A-D
Shaw Environmental, Inc.
Aerojet General Corp
6
369
1137720
9/21/2011
EPA informational response to 1/5/11 comments
submitted by A Tsao on 10/2010 final boundary
OU RI and risk assessment
EPA, Region IX
Allen Tsao / NONE
6
8
1137716
12/6/2011
Overheads (24): Aerojet Boundary OU feasibility
study (FS) update, community advisory group
mtg
EPA, Region IX
Aerojet Community Advisory Group
6
24
5 OF 7
-------
Appendix C: Administration Record Index
Doc ID
Doc Date
Title
Author
Addressee
OU
Pgs
1137731
3/22/2012
Ltr: Comments on necessity of quantitatively
evaluating home produce pathway for boundary
OU human health risk assessment (HHRA),
presented at Aerojet Community Advisory Group
(CAG)mtg 3/21/12
Allen Tsao / Aerojet Community Advisory
Group
Janis Heple / Aerojet Community Advisory
Group
Jimmy Spearow / Aerojet Community
Advisory Group
Gary Riley / EPA, Region IX
Alexander MacDonald / CA RWQCB,
Central Valley Region
Ed Cargile / Cal-EPA, DTSC
6
3
1137735
3/22/2012
Email: Figs to assist with lead interpretation,
location and concentration, w/attchs
Chris Fennessy / Aerojet General Corp
Alexander MacDonald / CA RWQCB,
Central Valley Region
Ed Cargile / Cal-EPA, DTSC
Gary Riley / EPA, Region IX
6
5
1137725
4/30/2012
Email: Discusses and transmits 2 maps of site
showing soil vapor risk areas, w/attchs
Chris Fennessy / Aerojet General Corp
Gary Riley / EPA, Region IX
6
4
1137734
6/15/2012
Email: Discusses and transmits figs to respond to
Community Advisory Group comments on
perchlorate uptake in home grown produce,
w/attchs
Chris Fennessy / Aerojet General Corp
Gary Riley / EPA, Region IX
6
3
1137729
7/5/2012
Ltr: Comments on final boundary OU-6 RI and
risk assessment, w/attch
Aerojet Community Advisory Group
Gary Riley / EPA, Region IX
6
9
1137722
7/24/2012
Ltr: Agrees with 7/5/12 email fr chair of
Community Advisory Group re perchlorate in
home-grown produce and concern with slow
pace of cleanup
Stephen Green / Save the American River
Assn, Inc.
Gary Riley / EPA, Region IX
6
3
1136593
9/1/2012
Rev final feasibility study (FS) for boundary area
operable unit (OU6), v3
Shaw Environmental, Inc.
Aerojet General Corp
6
414
1137723
11/21/2012
Email: Calculates concentration of TCE in soil
vapor and transmits figs 1-29 through 1-36 to
determine risk at site
Chris Fennessy / Aerojet General Corp
Gary Riley / EPA, Region IX
6
10
1137719
12/4/2012
Responses to Community Advisory Group
comments on final boundary OU6 RI and
human health and ecological risk assessment,
w/LL to J Heple fr P Kvam
Aerojet General Corp
Aerojet Community Advisory Group
6
15
6 OF 7
-------
Appendix C: Administration Record Index
Doc ID
Doc Date
Title
Author
Addressee
OU
Pgs
1136590
12/10/2012
Perchlorate uptake in home garden produce
Intertox, Inc.
Intertox, Inc.
6
21
2275811
12/31/2012
Ltr: Review of final FS for boundary area OU-6,
v 3, w/attchs
Alexander MacDonald / CA RWQCB,
Central Valley Region
Chris Fennessy / Aerojet General Corp
6
11
2276027
4/30/2013
List of US EPA guidance documents consulted
during development and selection of response
action for site
EPA, Region IX
6
7
1137869
5/1/2013
Fact Sheet: Proposed plan for Boundary OU
cleanup - EPA requests public comment on
proposed plan for Boundary OU of site
(06 CF 005)
EPA, Region IX
6
20
1138429
5/15/2013
Overheads (24): PowerPoint presentation on
Boundary Operable Unit (OU-6) proposed plan
Gary Riley / EPA, Region IX
6
24
1137733
01/01/1111
PowerPoint presentation - Exposure pathways of
perchlorate in vegetables, and complexity of
measurement
EPA, Region IX
6
13
7 OF 7
-------
ilix I)
Detailed Description and Cost Data
-------
TABLE D-1
Summary of Estimated Costs for Alternative 2 - Institutional Controls
Boundary OU Record of Decision
Estimated
Present
Description
Quantity
Unit
Unit Cost
Cost
Worth Cost3 Assumptions
Capital Costs
Institutional Controls
1
LS
$14,000
$14,000
$14,000 From Final Boundary OU FS (Shaw, 2012). Total capital cost of $83,000
divided equally among 6 OUs. Includes 20% contingency.
Subtotal - Capital Costs
$14,000
$14,000
Annual Costs
Institutional Controls
29
LS
$3,000
$87,000
$66,000 From Final Boundary OU FS (Shaw, 2012). Total annual cost of $20,000
divided equally among 6 OUs. Includes 20% contingency.
Subtotal - Annual Costs
$87,000
$66,000
Periodic Costs
Institutional Controls
6
LS
$6,000
$36,000
$27,000 From Final Boundary OU FS (Shaw, 2012). Periodic costs are incurred
every 5 years. Total periodic cost of $36,000 divided equally among 6 OUs.
Includes 20% contingency.
Subtotal - Periodic Costs
$36,000
$27,000
Total
S137.000
S107.000
a The discount rate used for the calculations was 1.9 percent and was taken from Appendix C of the Office of Management and Budget Circular A-94 (December 2013) for real discount rates over a 30-year
period.
Page 1 of 1
-------
TABLE D-2
Summary of Estimated Costs for Alternative 3 - Containment and Engineering Controls
Boundary OU Record of Decision
Estimated
Present
Description
Quantity
Unit
Unit Cost
Cost
Worth Cost3
Assumptions
Capital Costs
Institutional Controls
1
LS
$14,000
$14,000
$14,000
From Final Boundary OU FS (Shaw, 2012). Total capital cost of $83,000
divided equally among 6 OUs. Includes 20% contingency.
Vapor Barriersb
2,404,000
ft2
$0.50
$1,202,000
$924,000
From Final Boundary OU FS (Shaw, 2012). Assumes development occurs
in 15 years.
Ventilation
1
LS
$1,053,000
$1,053,000
$1,053,000
From Final Boundary OU FS (Shaw, 2012). Includes 33% indirect capital
costs (project management, engineering design, and construction
management) and 25% contingency.
Capping
13.033
acre
$124,000
$1,616,000
$1,616,000
Based on average unit cost from Final Boundary OU FS (Shaw, 2012).
Includes 33% indirect capital costs (project management, engineering
design, and construction management) and 25% contingency.
Backfilling at DPEB-R-1
1
LS
$213,000
$213,000
$213,000
Based on unit cost from Final Boundary OU FS (Shaw, 2012). Assumes
area will be backfilled so that the contaminated soil is approximately 10 feet
bgs. Includes 45% indirect capital costs (project management, engineering
design, and construction management) and 25% contingency.
Soil Sampling at AW-R-14
1
LS
$15,000
$15,000
$15,000
From Final Boundary OU FS (Shaw, 2012). Assumes 6 borings. Includes
25% contingency.
Subtotal - Capital Costs
$4,113,000
$3,835,000
Annual Costs
Institutional Controls
29
LS
$3,000
$87,000
$66,000 From Final Boundary OU FS (Shaw, 2012). Total annual cost of $20,000
divided equally among 6 OUs. Includes 20% contingency.
Ventilation OM&M
29
LS
$148,000
$4,292,000
$3,277,000 From Final Boundary OU FS (Shaw, 2012). Includes 25% contingency.
Subtotal - Annual Costs
$4,379,000
$3,343,000
Periodic Costs
Institutional Controls
6
LS
$6,000
$36,000
$27,000
From Final Boundary OU FS (Shaw, 2012). Periodic costs are incurred
every 5 years. Total periodic cost of $36,000 divided equally among 6 OUs.
Includes 20% contingency.
Capping O&M
6
LS
$216,000
$1,296,000
$955,000
Based on average unit cost of $16,600 per acre per year from Final
Boundary OU FS (Shaw, 2012). Includes 33% indirect capital costs (project
management, engineering design, and construction management) and
25% contingency. Incurred every 5 years.
Subtotal - Periodic Costs
$1,332,000
$982,000
Total
$9,824,000
$8,160,000
a The discount rate used for the calculations was 1.9 percent and was taken from Appendix C of the Office of Management and Budget Circular A-94 (December 2013) for real discount rates over a 30-year
period.
b As presented in the Final Boundary OU FS (Shaw, 2012), it is assumed that for any future residential development that would require vapor intrusion controls, the developer would install a moisture barrier
with taped seams as part of any new construction and the costs of the materials and installation for the moisture barrier would be borne by the developer. It is further assumed that the only difference
between a moisture barrier and a vapor barrier is that seals/taping be provided around any utility penetrations (e.g., plumbing piping) of the moisture barrier. Based on a verbal quotation from Regenesis, the
estimated cost to install a moisture barrier under a future residential scenario is $3.00 per square foot. For purposes of estimating costs for the FS, it was assumed that the incremental material and labor
cost for sealing/taping utility penetrations is $0.50 per square foot.
Page 1 of 1
-------
TABLE D-3
Summary of Estimated Costs for Alternative 4 - Source Removal/Reduction
Boundary OU Record of Decision
Description
Quantity Unit
Unit Cost
Estimated
Cost
Present
Worth Cost3
Assumptions
Capital Costs
Institutional Controls
Excavation
SVE for Admin Area (AE-SV-R-4/AE-SV-
R-5, AE-SV-R-6, and AE-SV-R-7/ AE-SV-
R-8)
SVE for Admin Area (AE-SV-R-1/AE-SV-
R-2)
SVE for WLLO Area, Line 2 (L2-SV-R-1 1
and L2-SV-R-2)
SVE for WLLO Area, Line 5 (L5-SV-R-1
and L5-SV-R-2)
SVE for Chemical Plant 2 (CP2-SV-R-
1/CP2-SV-R-2)
SVE for Chemical Plant 2 (CP2-SV-R- 1
3/CP2-SV-R-4/CP2-SV-R-5)
Soil Flushing at WLLO Area, Line 2 (L2- 1
R-4, L2-R-5, and L2-R-9)
Water Jetting Culvert at AE-R-9 1
LS
ft3
LS
LS
LS
LS
LS
LS
LS
LS
$14,000 $14,000 $14,000 From Final Boundary OU FS (Shaw, 2012). Total capital cost of $83,000
divided equally among 6 OUs. Includes 20% contingency.
$4.08 $13,839,000 $13,839,000 Based on average unit cost from Final Boundary OU FS (Shaw, 2012).
Includes 33% indirect capital costs (project management, engineering
design, and construction management) and 25% contingency.
Based on unit costs from Final Boundary OU FS (Shaw, 2012). Assumes
12 shallow (10 ft) and 18 deeper (20 ft) wells at 30 cfm per well. Includes
33% indirect capital costs (project management, engineering design, and
construction management) and 25% contingency.
Based on unit costs from Final Boundary OU FS (Shaw, 2012). Assumes 4
shallow (10 ft) and 8 deeper (20 ft) wells at 30 cfm per well. Includes 33%
indirect capital costs (project management, engineering design, and
construction management) and 25% contingency.
From Final Boundary OU FS (Shaw, 2012). Assumes 1 shallow (10 ft) and
8 deeper (20 ft) wells at 30 cfm per well. Includes 33% indirect capital costs
(project management, engineering design, and construction management)
and 25% contingency.
From Final Boundary OU FS (Shaw, 2012). Assumes 1 shallow (10 ft) and
1 deeper (20 ft) well at 30 cfm per well. Includes 33% indirect capital costs
(project management, engineering design, and construction management)
and 25% contingency.
Based on unit costs from Final Boundary OU FS (Shaw, 2012). Assumes 2
shallow (10 ft) and 12 deeper (20 ft) wells at 30 cfm per well. Includes 33%
indirect capital costs (project management, engineering design, and
construction management) and 25% contingency.
$410,000 Based on unit costs from Final Boundary OU FS (Shaw, 2012). Assumes 3
shallow (10 ft) and 6 deeper (20 ft) wells at 30 cfm per well. Includes 33%
indirect capital costs (project management, engineering design, and
construction management) and 25% contingency.
$170,000 $170,000 $170,000 From Final Boundary OU FS (Shaw, 2012). Assumes 4 extraction wells.
Includes 33% indirect capital costs (project management, engineering
design, and construction management) and 25% contingency.
$8,000 $8,000 $8,000 From Final Boundary OU FS (Shaw, 2012). Assumes 200 ft of culvert.
Includes 25% contingency.
$1,620,000 $1,620,000 $1,620,000
$460,000 $460,000 $460,000
$390,000 $390,000 $390,000
$110,000 $110,000 $110,000
$490,000 $490,000 $490,000
$410,000 $410,000
Subtotal - Capital Costs
$17,511,000 $17,511,000
Page 1 of 2
-------
TABLE D-3
Summary of Estimated Costs for Alternative 4 - Source Removal/Reduction
Boundary OU Record of Decision
Estimated
Present
Description
Quantity
Unit
Unit Cost
Cost
Worth Cost3
Assumptions
Annual Costs
Institutional Controls
29
LS
$3,000
$87,000
$66,000
From Final Boundary OU FS (Shaw, 2012). Total annual cost of $20,000
divided equally among 6 OUs. Includes 20% contingency.
SVE OM&M for Admin Area (AE-SV-R-
7
LS
$77,000
$539,000
$500,000
Based on unit costs from Final Boundary OU FS (Shaw, 2012). Includes
4/AE-SV-R-5, AE-SV-R-6, and AE-SV-R-
25% contingency. Cost incurred years 1 through 7.
7/ AE-SV-R-8)
SVE OM&M for Admin Area (AE-SV-R-
7
LS
$77,000
$539,000
$500,000
Based on unit costs from Final Boundary OU FS (Shaw, 2012). Includes
1/AE-SV-R-2)
25% contingency. Cost incurred years 1 through 7.
SVE OM&M for WLLO Area, Line 2 (L2-
7
LS
$77,000
$539,000
$500,000
From Final Boundary OU FS (Shaw, 2012). Includes 25% contingency.
SV-R-1 and L2-SV-R-2)
Cost incurred years 1 through 7.
SVE OM&M for WLLO Area, Line 5 (L5-
7
LS
$53,000
$371,000
$344,000
From Final Boundary OU FS (Shaw, 2012). Includes 25% contingency.
SV-R-1 and L5-SV-R-2)
Cost incurred years 1 through 7.
SVE OM&M for Chemical Plant 2 (CP2-
7
LS
$77,000
$539,000
$500,000
From Final Boundary OU FS (Shaw, 2012). Includes 25% contingency.
SV-R-1/CP2-SV-R-2)
Cost incurred years 1 through 7.
SVE OM&M for Chemical Plant 2 CP2-
7
LS
$77,000
$539,000
$500,000
From Final Boundary OU FS (Shaw, 2012). Includes 25% contingency.
SV-R-3/CP2-SV-R-4/CP2-SV-R-5)
Cost incurred years 1 through 7.
Soil Flushing OM&M
9
LS
$34,000
$306,000
$279,000
From Final Boundary OU FS (Shaw, 2012). Includes 25% contingency.
Cost incurred years 1 through 9.
Subtotal - Annual Costs
$3,459,000
$3,189,000
Periodic Costs
Institutional Controls
6
LS
$6,000
$36,000
$27,000 From Final Boundary OU FS (Shaw, 2012). Periodic costs are incurred
every 5 years. Total periodic cost of $36,000 divided equally among 6 OUs.
Includes 20% contingency.
Subtotal - Periodic Costs
$36,000
$27,000
Total
$21,006,000
$20,727,000
a The discount rate used for the calculations was 1.9 percent and was taken from Appendix C of the Office of Management and Budget Circular A-94 (December 2013) for real discount rates over a 30-year
period.
b As presented in the Final Boundary OU FS (Shaw, 2012), it is assumed that for any future residential development that would require vapor intrusion controls, the developer would install a moisture barrier with
taped seams as part of any new construction and the costs of the materials and installation for the moisture barrier would be borne by the developer. It is further assumed that the only difference between a
moisture barrier and a vapor barrier is that seals/taping be provided around any utility penetrations (e.g., plumbing piping) of the moisture barrier. Based on a verbal quotation from Regenesis, the estimated cost
to install a moisture barrier under a future residential scenario is $3.00 per square foot. For purposes of estimating costs for the FS, it was assumed that the incremental material and labor cost for sealing/taping
utility penetrations is $0.50 per square foot.
Page 2 of 2
-------
TABLE D-4
Summary of Estimated Costs for Selected Remedy
Boundary OU Record of Decision
Description
Quantity Unit
Unit Cost
Estimated
Cost
Present
Worth Cost3
Assumptions
Capital Costs
Institutional Controls
Vapor Barriersb
Ventilation
Excavation
Capping
Backfilling at DPEB-R-1
Soil Sampling at AW-R-14 1
SVE for Admin Area (AE-SV-R-4/AE-SV- 1
R-5, AE-SV-R-6, and AE-SV-R-7/ AE-SV-
R-8)
SVE for Admin Area (AE-SV-R-1/AE-SV- 1
R-2)
SVE for WLLO Area, Line 2 (L2-SV-R-1 1
and L2-SV-R-2)
SVE for WLLO Area, Line 5 (L5-SV-R-1
and L5-SV-R-2)
SVE for Chemical Plant 2 (CP2-SV-R-
1/CP2-SV-R-2)
LS
LS
3,134,400 ft3
1.295 acre
LS
LS
LS
LS
LS
LS
LS
$14,000 $14,000 $14,000 From Final Boundary OU FS (Shaw, 2012). Total capital cost of $83,000
divided equally among 6 OUs. Includes 20% contingency.
$0.50 $1,202,000 $924,000 From Final Boundary OU FS (Shaw, 2012). Assumes development occurs
in 15 years.
$1,053,000 $1,053,000 $1,053,000 From Final Boundary OU FS (Shaw, 2012). Includes 33% indirect capital
costs (project management, engineering design, and construction
management) and 25% contingency.
Based on average unit cost from Final Boundary OU FS (Shaw, 2012).
Includes 33% indirect capital costs (project management, engineering
design, and construction management) and 25% contingency.
$161,000 $161,000 Based on average unit cost from Final Boundary OU FS (Shaw, 2012).
Includes 33% indirect capital costs (project management, engineering
design, and construction management) and 25% contingency.
Based on unit cost from Final Boundary OU FS (Shaw, 2012). Assumes
area will be backfilled so that the contaminated soil is approximately 10 feet
bgs. Includes 45% indirect capital costs (project management, engineering
design, and construction management) and 25% contingency.
$15,000 $15,000 From Final Boundary OU FS (Shaw, 2012). Assumes 6 borings. Includes
25% contingency.
$1,620,000 $1,620,000 Based on unit costs from Final Boundary OU FS (Shaw, 2012). Assumes
12 shallow (10 ft) and 18 deeper (20 ft) wells at 30 cfm per well. Includes
33% indirect capital costs (project management, engineering design, and
construction management) and 25% contingency.
Based on unit costs from Final Boundary OU FS (Shaw, 2012). Assumes 4
shallow (10 ft) and 8 deeper (20 ft) wells at 30 cfm per well. Includes 33%
indirect capital costs (project management, engineering design, and
construction management) and 25% contingency.
$390,000 From Final Boundary OU FS (Shaw, 2012). Assumes 1 shallow (10 ft) and
8 deeper (20 ft) wells at 30 cfm per well. Includes 33% indirect capital costs
(project management, engineering design, and construction management)
and 25% contingency.
$110,000 $110,000 $110,000 From Final Boundary OU FS (Shaw, 2012). Assumes 1 shallow (10 ft) and
1 deeper (20 ft) well at 30 cfm per well. Includes 33% indirect capital costs
(project management, engineering design, and construction management)
and 25% contingency.
$490,000 $490,000 $490,000 Based on unit costs from Final Boundary OU FS (Shaw, 2012). Assumes 2
shallow (10 ft) and 12 deeper (20 ft) wells at 30 cfm per well. Includes 33%
indirect capital costs (project management, engineering design, and
construction management) and 25% contingency.
$4.08 $12,788,000 $12,788,000
$124,000
$213,000 $213,000 $213,000
$15,000
$1,620,000
$460,000 $460,000 $460,000
$390,000 $390,000
Page 1 of 3
-------
TABLE D-4
Summary of Estimated Costs for Selected Remedy
Boundary OU Record of Decision
Estimated
Present
Description
Quantity
Unit
Unit Cost
Cost
Worth Cost3
Assumptions
SVE for Chemical Plant 2 (CP2-SV-R-
1
LS
$410,000
$410,000
$410,000
Based on unit costs from Final Boundary OU FS (Shaw, 2012). Assumes 3
3/CP2-SV-R-4/CP2-SV-R-5)
shallow (10 ft) and 6 deeper (20 ft) wells at 30 cfm per well. Includes 33%
indirect capital costs (project management, engineering design, and
construction management) and 25% contingency.
Soil Flushing at WLLO Area, Line 2 (L2-
1
LS
$170,000
$170,000
$170,000
From Final Boundary OU FS (Shaw, 2012). Assumes 4 extraction wells.
R-4, L2-R-5, and L2-R-9)
Includes 33% indirect capital costs (project management, engineering
design, and construction management) and 25% contingency.
Water Jetting Culvert at AE-R-9
1
LS
$8,000
$8,000
$8,000
From Final Boundary OU FS (Shaw, 2012). Assumes 200 ft of culvert.
Includes 25% contingency.
Subtotal - Capital Costs
$19,104,000
$18,826,000
Annual Costs
Institutional Controls
29
LS
$3,000
$87,000
$66,000
From Final Boundary OU FS (Shaw, 2012). Total annual cost of $20,000
divided equally among 6 OUs. Includes 20% contingency.
Ventilation OM&M
29
LS
$148,000
$4,292,000
$3,277,000
From Final Boundary OU FS (Shaw, 2012). Includes 25% contingency.
SVE OM&M for Admin Area (AE-SV-R-
7
LS
$77,000
$539,000
$500,000
From Final Boundary OU FS (Shaw, 2012). Includes 25% contingency.
4/AE-SV-R-5, AE-SV-R-6, and AE-SV-R-
Cost incurred years 1 through 7.
7/ AE-SV-R-8)
SVE OM&M for Admin Area (AE-SV-R-
7
LS
$77,000
$539,000
$500,000
Based on unit costs from Final Boundary OU FS (Shaw, 2012). Includes
1/AE-SV-R-2)
25% contingency. Cost incurred years 1 through 7.
SVE OM&M for WLLO Area, Line 2 (L2-
7
LS
$77,000
$539,000
$500,000
From Final Boundary OU FS (Shaw, 2012). Includes 25% contingency.
SV-R-1 and L2-SV-R-2)
Cost incurred years 1 through 7.
SVE OM&M for WLLO Area, Line 5 (L5-
7
LS
$53,000
$371,000
$344,000
From Final Boundary OU FS (Shaw, 2012). Includes 25% contingency.
SV-R-1 and L5-SV-R-2)
Cost incurred years 1 through 7.
SVE OM&M for Chemical Plant 2 (CP2-
7
LS
$77,000
$539,000
$500,000
From Final Boundary OU FS (Shaw, 2012). Includes 25% contingency.
SV-R-1/CP2-SV-R-2)
Cost incurred years 1 through 7.
SVE OM&M for Chemical Plant 2 CP2-
7
LS
$77,000
$539,000
$500,000
From Final Boundary OU FS (Shaw, 2012). Includes 25% contingency.
SV-R-3/CP2-SV-R-4/CP2-SV-R-5)
Cost incurred years 1 through 7.
Soil Flushing OM&M
9
LS
$34,000
$306,000
$279,000
From Final Boundary OU FS (Shaw, 2012). Includes 25% contingency.
Cost incurred years 1 through 9.
Subtotal - Annual Costs $7,751,000 $6,466,000
Page 2 of 3
-------
TABLE D-4
Summary of Estimated Costs for Selected Remedy
Boundary OU Record of Decision
Estimated
Present
Description
Quantity
Unit
Unit Cost
Cost
Worth Cost3 Assumptions
Periodic Costs
Institutional Controls
6
LS
$6,000
$36,000
$27,000 From Final Boundary OU FS (Shaw, 2012). Periodic costs are incurred
every 5 years. Total periodic cost of $36,000 divided equally among 6 OUs.
Includes 20% contingency.
Capping O&M
6
LS
$21,000
$126,000
$93,000 Based on average unit cost of $16,600 per acre per year from Final
Boundary OU FS (Shaw, 2012). Includes 33% indirect capital costs (project
management, engineering design, and construction management) and
25% contingency. Incurred every 5 years.
Subtotal - Periodic Costs
$36,000
$27,000
Total
$26,891,000
$25,319,000
a The discount rate used for the calculations was 1.9 percent and was taken from Appendix C of the Office of Management and Budget Circular A-94 (December 2013) for real discount rates over a 30-year
period.
b As presented in the Final Boundary OU FS (Shaw, 2012), it is assumed that for any future residential development that would require vapor intrusion controls, the developer would install a moisture barrier with
taped seams as part of any new construction and the costs of the materials and installation for the moisture barrier would be borne by the developer. It is further assumed that the only difference between a
moisture barrier and a vapor barrier is that seals/taping be provided around any utility penetrations (e.g., plumbing piping) of the moisture barrier. Based on a verbal quotation from Regenesis, the estimated cost
to install a moisture barrier under a future residential scenario is $3.00 per square foot. For purposes of estimating costs for the FS, it was assumed that the incremental material and labor cost for sealing/taping
utility penetrations is $0.50 per square foot.
Page 3 of 3
-------
TABLE D-5
Summary of Remedial Action Areas
Boundary OU Record of Decision
Remedv Evaluation
Selected Remedv
Capping
Excavation
Capping
Excavation
Remedial Action
Area
Depth
Area
Volume
Area
Volume
Area
Selected Alternative
Alternatives Evaluated in ROD
Area (acres)
(ft2)
(ft bgs)
(acres)
(ft3)
(acres)
(ft3)
Administration Area
East
AE-R-1
Alternative 3 - Containment and Engineering
(Capping)
Alternative 2 - Institutional Controls
Alternative 3 - Containment and Engineering Controls (Capping)
0.051
2,223
0.051
0
0.051
0
AE-R-2
Alternative 3 - Containment and Engineering
(Capping)
Alternative 2 - Institutional Controls
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
0.418
18,210
6
0.418
109,300
0.418
0
AE-R-3
Alternative 3 - Containment and Engineering
(Capping)
Alternative 2 - Institutional Controls
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
0.119
5,199
4
0.119
20,800
0.119
0
AE-R-4
Alternative 3 - Containment and Engineering
(Capping)
Alternative 2 - Institutional Controls
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
0.050
2,160
6
0.05
13,000
0.05
0
AE-R-5/AE-R-6
Alternative 3 - Containment and Engineering
(Capping)
Alternative 2 - Institutional Controls
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
0.657
28,628
4
0.657
114,500
0.657
0
AE-R-7
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.046
2,004
12
0.046
24,000
0
24,000
(Excavation)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
AE-R-8
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.213
9,278
2
0
18,600
0
18,600
(Excavation)
Alternative 4 - Source Removal/Reduction (Excavation)
AE-R-9
Alternative 4 - Source Removal/Reduction
(Excavation)
Alternative 2 - Institutional Controls
Alternative 4 - Source Removal/Reduction (Excavation)
0
0
0
0
AE-SV-R-1 /AE-SV-R-2
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
1.913
83,312
0
0
0
0
(SVE)
Alternative 4 - Source Removal/Reduction (SVE)
AE-SV-R-3
Alternative 3 - Containment and Engineering
Controls (Vapor Mitigation)
Alternative 2 - Institutional Controls
Alternative 3 - Containment and Engineering Controls (Vapor Mitigation)
0
0
0
0
AE-SV-R-4/AE-SV-R-5
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.926
40,335
0.926
0
0
0
(SVE)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (SVE)
AE-SV-R-6
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.810
35,280
0.81
0
0
0
(SVE)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (SVE)
AE-SV-R-7/AE-SV-R-8
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
4.605
200,584
4.605
0
0
0
(SVE)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (SVE)
Page 1 of 4
-------
TABLE D-5
Summary of Remedial Action Areas
Boundary OU Record of Decision
Remedv Evaluation
Selected Remedv
Capping
Excavation
Capping
Excavation
Remedial Action
Area
Depth
Area
Volume
Area
Volume
Area
Selected Alternative
Alternatives Evaluated in ROD
Area (acres)
(ft2)
(ft bgs)
(acres)
(ft3)
(acres)
(ft3)
Administration Area
West
AW- R-1 / A W- R- 2/
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.258
80,802
2
0.258
161,600
0
161,600
AW-R-11
(Excavation)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
AW-R-3
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.025
8,390
1.5
0.025
12,600
0
12,600
(Excavation)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
AW-R-4/AW-R-5
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.042
1,830
2
0.042
3,700
0
3,700
(Excavation)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
AW-R-6
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.289
12,589
2
0.289
25,200
0
25,200
(Excavation)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
AW-R-7/AW-R-14
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.459
30,480
6
0.459
182,900
0
182,900
(Excavation)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
AW-R-8/AW-R-9/
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.410
95,863
12
0.41
1,150,400
0
1,150,400
AW-R-10/
(Excavation)
Alternative 3 - Containment and Engineering Controls (Capping)
AW-R-12/AW-R-13
Alternative 4 - Source Removal/Reduction (Excavation)
AW-R-15
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.048
2,082
15
0
31,200
0
31,200
(Excavation)
Alternative 4 - Source Removal/Reduction (Excavation)
AW-R-16
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.355
15,472
2
0
30,900
0
30,900
(Excavation)
Alternative 4 - Source Removal/Reduction (Excavation)
AW-SV-R-1
Alternative 3 - Containment and Engineering
Alternative 2 - Institutional Controls
0
0
0
0
Controls (Vapor Mitigation)
Alternative 3 - Containment and Engineering Controls (Vapor Mitigation)
Line 2 Region / Open Space 5
L2-R-1
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.040
1,742
3.5
0.04
6,100
0
6,100
(Excavation)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
L2-R-2/L2-R-3
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.226
15,294
4
0.226
61,200
0
61,200
(Excavation)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
L2-R-4/L2-R-5/
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.082
15,830
12
0.082
190,000
0
190,000
L2-R-9
(Excavation with Soil Flushing and Air
Alternative 3 - Containment and Engineering Controls (Capping)
Stripping)
Alternative 4 - Source Removal/Reduction (Excavation with Soil Flushing and
Air Stripping)
L2-R-6
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.042
7,539
5.5
0.042
41,500
0
41,500
(Excavation)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
L2-R-7/L2-R-8
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.030
14,028
12
0.03
168,300
0
168,300
(Excavation)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
L2-R-10
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.021
900
5
0
4,500
0
4,500
(Excavation)
Alternative 4 - Source Removal/Reduction (Excavation)
L2-R-11
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.064
2,800
5
0
14,000
0
14,000
(Excavation)
Alternative 4 - Source Removal/Reduction (Excavation)
L2-SV-R-1
Alternative 3 - Containment and Engineering
Alternative 2 - Institutional Controls
0
0
0
0
Controls (Vapor Mitigation)
Alternative 3 - Containment and Engineering Controls (Vapor Mitigation)
L2-SV-R-2
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.065
2,831
0.065
0
0
0
(SVE)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (SVE)
L2-SV-R-3
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.029
1,263
0.029
0
0
0
(SVE)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (SVE)
Page 2 of 4
-------
TABLE D-5
Summary of Remedial Action Areas
Boundary OU Record of Decision
Remedv Evaluation
Selected Remedv
Capping
Excavation
Capping
Excavation
Remedial Action
Area
Depth
Area
Volume
Area
Volume
Area
Selected Alternative
Alternatives Evaluated in ROD
Area (acres)
(ft2)
(ft bgs)
(acres)
(ft3)
(acres)
(ft3)
Line 5 North / Open Space 7
0.000
L5-R-1
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.129
5,619
1.5
0.129
8,400
0
8,400
(Excavation)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
L5-R-2
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.011
479
12
0.011
5,700
0
5,700
(Excavation)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
L5-R-3
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.015
663
3
0
2,000
0
2,000
(Excavation)
Alternative 4 - Source Removal/Reduction (Excavation)
L5-R-4
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.015
663
3
0
2,000
0
2,000
(Excavation)
Alternative 4 - Source Removal/Reduction (Excavation)
L5-R-5
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.032
1,385
2
0
2,800
0
2,800
(Excavation)
Alternative 4 - Source Removal/Reduction (Excavation)
L5-SV-R-1
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.057
2,483
0.057
0
0
0
(SVE)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (SVE)
L5-SV-R-2
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.057
2,483
0.057
0
0
0
(SVE)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (SVE)
L5-SV-R-3
Alternative 3 - Containment and Engineering
Controls (Vapor Mitigation)
Alternative 2 - Institutional Controls
Alternative 3 - Containment and Engineering Controls (Vapor Mitigation)
0
0
0
0
Buffalo Creek
BC-R-1
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
2.647
115,303
2.5
0
288,300
0
288,300
(Excavation)
Alternative 4 - Source Removal/Reduction (Excavation)
BC-R-2
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
1.209
52,664
2
0
105,300
0
105,300
(Excavation)
Alternative 4 - Source Removal/Reduction (Excavation)
West Lakes / Open Space 6
WL-R-1
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.026
1,133
6
0.026
6,800
0
6,800
(Excavation)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (Excavation)
Magazine Area / Open Space 3
MA-R-1
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.052
2,270
12
0
27,200
0
27,200
(Excavation)
Alternative 4 - Source Removal/Reduction (Excavation)
MA-SV-R1
Alternative 2 - Institutional Controls
Alternative 2 - Institutional Controls
0
0
0
0
Chemical Plant 2 / Open Spaces 1, 2, and 4
CP2-R-1 /CP2-R-8/
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
1.056
46,021
2
0
92,000
0
92,000
CP2-R-9/CP2-R-10/
(Excavation)
Alternative 4 - Source Removal/Reduction (Excavation)
CP2-R-11
CP2-R-2/CP2-R-3/
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.184
73,871
6
0.184
443,200
0
443,200
CP2-R-4/CP2-R-5/
(Excavation)
Alternative 3 - Containment and Engineering Controls (Capping)
CP2-R-6
Alternative 4 - Source Removal/Reduction (Excavation)
CP2-R-7
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.069
3,006
0
3,000
0
3,000
(Excavation)
Alternative 4 - Source Removal/Reduction (Excavation)
CP2-R-12
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
0.069
3,006
7
0
21,000
0
21,000
(Excavation)
Alternative 4 - Source Removal/Reduction (Excavation)
CP2-SV-R-1/CP2-SV-R-2
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
1.847
80,460
1.847
0
0
0
(SVE)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (SVE)
CP2-SV-R-3/CP2-SV-R-
Alternative 4 - Source Removal/Reduction
Alternative 2 - Institutional Controls
1.043
45,451
1.043
0
0
0
4/CP2-SV-R-5
(SVE)
Alternative 3 - Containment and Engineering Controls (Capping)
Alternative 4 - Source Removal/Reduction (SVE)
CP2-SV-R-6
Alternative 2 - Institutional Controls
Alternative 2 - Institutional Controls
0
0
0
0
Page 3 of 4
-------
TABLE D-5
Summary of Remedial Action Areas
Boundary OU Record of Decision
Remedv Evaluation
Selected Remedv
Capping
Excavation
Capping
Excavation
Remedial Action
Area
Depth
Area
Volume
Area
Volume
Area
Selected Alternative
Alternatives Evaluated in ROD
Area (acres)
(ft2)
(ft bgs)
(acres)
(ft3)
(acres)
(ft3)
Dredge Pit and Eastern Basin
DPEB-R-1
Alternative 3 - Containment and Engineering
Alternative 2 - Institutional Controls
0.549
23,928
10
0
0
0
0
(Backfilling)
Alternative 3 - Containment and Engineering Controls (Backfilling)
DPEB-SV-R-1
Alternative 2 - Institutional Controls
Alternative 2 - Institutional Controls
0
0
0
0
TOTAL
13.033
3,392,000
1.295
3,134,400
Notes:
ft bgs = feet below ground surface
ft2 - square feet
ft3 - cubic feet
SVE = soil vapor extraction
Page 4 of 4
-------
endix E
Responsiveness i ฆ 111 ฆฆ I i.t|i.tj. .1 li'II1 mments
-------
Appendix E-l. Public Meeting Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from the Community Advisory Group
Comment #
Comment
Response
Public Comments Made Verbally During the Public Meeting for the Proposed Plan for OU-6 Cleanup on May 15, 2013
These comments were consolidated from the transcript of the meeting. Hie transcript of the meeting are in the Administrative Record.
1.
Commenter: Mr. Rick Bettis
This is part of the Central Groundwater Basin and there's, you know, significant
changes in land use land and there's changes in water supply unless they implement
the, you know, the (inaudible) project and all. Are those sorts of tilings being
monitored? Because when you start changing the groundwater levels outside of the
project area that could impact movements within the area.
The contaminated groundwater beneath the Aerojet Superfund Site, including
groundwater beneath OU-6, is being addressed as part of the ongoing interim
and final remedial actions to provide hydraulic containment and remediation of
the contamination associated with releases from Aerojet. As described in the
proposed plan, groundwater remediation is being conducted on an Aerojet
sitewide basis. These final and interim remedies for the groundwater
are managed under the OU-3 ROD (EPA, 2001) and OU-5 Interim ROD for
Groundwater (EPA, 2011). The filial groundwater remedy with aquifer
restoration goals, will be documented in the sitewide ROD (OU-1 ROD). The
OU-3 and OU-5 RODs include more details on the ongoing remedial actions
for groundwater. Evaluations will consider the actual performance of the remedy
and incorporate water level monitoring that considers other uses of groundwater
in the area. EPA will continue these evaluations as required. It is not expected
that remediation of groundwater sources within OU-6 will impact groundwater
levels outside of OU-6.
2.
Commenter: Mr. Jimmy Spearow
Just a quick comment. That it's not clear at all in terms of what cleanup levels are in
various portions of the proposed plan, it's just not enough detail to see the different
sections there. Which sections would be cleaned up to unrestricted residential, for
example, versus there needs to be a lot more detail.
Cleanup levels for industrial/commercial land use and unrestricted use were
presented in Table 2 of the Proposed Plan for over 50 COCs. Current and future
land uses for OU-6 were evaluated in accordance with EPA's Reuse Directive,
and an assessment of these uses was presented in the Reuse Assessment for OU-5
and OU-6, dated July 24,2012. This document was presented at a CAG meeting,
and is located in the Administrative record for OU-6. The cleanup levels adopted
in the Selected Remedy are consistent with the target risk levels specified in the
Proposed Plan for the reasonably anticipated future land use for each Remedial
Action Area. See Tables 2-2 and 2-3 of this ROD.
3.
Commenter: Mr. Dan Waligora
I'm confused on that because typically if contamination is removed from the site then
land use controls, restrictions, and it could be the site is then can be considered
clean. So I'm the way you're describing that, it confuses me a lot more because if
it's removed, the site then can be opened for unrestricted use, therefore, it would
meet the criteria. So can you explain the confusion?
The commenter is correct that, for any areas where contamination is not present
above, or is remediated to risk levels that are suitable for unrestricted use, no land
use controls or restrictions would be required. However, OU-6 overlies impacted
groundwater that is being investigated and remediated under other OUs of the
Aerojet site. Therefore, institutional controls are being selected as a remedy
throughout the Boundary OU for groundwater. These restrictions include a
prohibition on well installation or use of groundwater from the OU-6 area
without regulatory Agency approval. In those areas where VOCs in groundwater
present a potential unacceptable risk from the vapor intrusion pathway, land use
controls will include requirements for engineering controls (e.g., vapor mitigation
systems).
1 OF 26
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Appendix E-l. Public Meeting Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from the Community Advisory Group
Comment # Comment Response
4.
Commenter: Mr. Jimmy Spearow
I think one of the real deficiencies of this is that it only addresses and talks quite
specifically here, for example on page 17:
"The preferred alternatives will remove or control sources of contamination
from Boundary OU source areas to protect current and future human and
ecological receptors, as well as prevent migration from these sources to
groundwater at concentrations that may impair beneficial use."
It only addresses contaminants that are, are in are from Boundary OU source areas
and the real problem is the contamination from other source areas. And if you look at
your own data set of the size of the source areas, of the contamination plumes, that
over the last 50 years or so they've migrated both TCE, NDMA and perchlorate have
migrated large distances, okay, very long distances.
And so even if you were to address these contaminants in Boundary OU, if there was
regulatory failure and that for some reason the contaminants in Island were not
addressed, then they are going to continue to migrate. They are going to come right
back in these areas and they are going to go further. So I think that there really needs
to be a coupling of the cleanup at Boundary with Island and other source units that
have multiple contaminants. That's one major point that's a flaw of this because it's
not going to address if there's regulatory failure. For some reason it's not carried
through, the cleanups in the other areas.
OU-6 ROD is intended to address soil contamination and potential sources of
contaminant migration to groundwater within the OU-6 land areas. Consistent
with EPA's policy for administratively managing complex sites, the Aerojet Site
was divided into a total of 9 OUs in a 2001 Partial Consent Decree to manage the
cleanup at the site. This approach allowed for a prioritized response to
groundwater containment and restoration under the Western Groundwater OU-3
and the Perimeter Groundwater OU-5 under RODs issued in 2001 and 2010,
respectively. Hie groundwater remedy associated with these operable units has
been constructed and is currently operating. The final groundwater remedy
with aquifer restoration goals, will be documented in the sitewide ROD
(OU-1 ROD). An extensive monitoring well network is used to monitor the
effectiveness of containment, restoration, and capture of this system. Annual
Effectiveness Evaluations consider the performance of this system and evaluate
any migration of plumes.
The more than 30-year record of groundwater monitoring data for the Aerojet
Site provides the Agencies with extensive information on the location of
groundwater plumes. The groundwater extraction and treatment systems installed
as part of OU-3 and OU-5 are required to be operated in an effective manner by
enforcement orders or consent decrees issued by EPA to Aerojet. In addition, the
Site is subject to Five Year Reviews that will evaluate the short- and long-term
protectiveness of the remedial actions in place at the Site.
EPA, the RWQCB, and DTSC provide oversight to this site through a Partial
Consent Decree and Orders that require Aerojet to comply with Agency
requirements. All remedies selected for the site will be evaluated for performance
and a lack of protectiveness will be corrected.
5.
Commenter: Mr. Jimmy Spearow
The second area I want to talk about is the cleanups, the cleanup levels. Now, the
CAG was not happy with the screening levels for contaminants in the RI in terms of
our comments not being addressed there. And that both oral and written, but
particularly the oral comments, not being addressed.
Mary Jo told us that they would take and - rather than go back and even put an
addendum on the RI or the RIFS, that they would present the cleanup levels in the
proposed plan. And yet when I look at - that they would use current toxicity criteria
for that. But when I look at this and look at your Table 2a I see all kinds of examples
where the toxicity criteria are incorrect, they are not the current toxicity criteria. I'll
just give a few examples where that there's plenty more but I'll just give a few
examples of where the toxicities here are really off, okay.
Cleanup levels presented in the Proposed Plan Table 2 presented risk levels
appropriate for future industrial/commercial or unrestricted use. EPA identified
errors in several of the values that were presented in the May 2013 Proposed Plan
that was the version available to commenters at the Public Meeting. The revised
PP, issued in June 2013, corrected these values.
The cleanup levels have been updated further since the Proposed Plan and are
shown in Table 2-2 and 2-3 of the ROD.
Naphthalene in OU-6 did not exceed screening levels for contact with soil for
industrial or unrestricted use. This COC does pose a potential risk to
groundwater, so the cleanup level presented in the updated Proposed Plan and in
the ROD is for that pathway.
2 OF 26
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Appendix E-l. Public Meeting Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from the Community Advisory Group
Comment # Comment Response
Hie commenter cites the current DTSC guidance for lead in soil (80 ppm for
unrestricted use and 320 ppm for industrial/commercial use).
For example, under hexavalent chromium. The soil cleanup level for the protection
of groundwater, this is on page 11. That you have it as the cleanup level as being
1,090 mg/kg. Well, the RSL for the protection of groundwater, the risk level is
5.9 x 10-4. So you're only off by seven orders of magnitude, okay. That's really
unacceptable, okay. It's much, much too high levels.
When we come to lead, there's statements in here that they will clean up lead to
10 micrograms per levels that would increase blood levels by no more than
10 micrograms per deciliter. No, it should be to increase by no more than one
microgram per deciliter, which is going to be 80 milligrams of lead in the soil.
And when it comes to naphthalene. There you list the screen level, the ERA ESL
cleanup at being 29 mg/kg. But under the soil cleanup level for the protection of
groundwater you list it as being 1.4 mg/kg, while the RSL is 4.7 x 10-4, so it's off by
four orders of magnitude. Your cleanup levels are four orders of magnitude too high.
Also there was no cleanup level for naphthalene in soil.
Two more examples are for TPH-diesel you've got it down as a soil cleanup level of
1,000 mg. Well, the soil cleanup level for the protection of groundwater for the
Regional Water Quality Control Board is 100 mg/kg. There's also issues it should
be 83 mg there for the protection of human health and soil. That's not listed.
Also for TCE. There was nothing listed there for soil protection, for protection of
groundwater, whereas the RSL is 1.6 x 10-4. Instead all you have listed is the 42.
The same tiling for the protection of residential use should be .91 mg/kg of TCE.
So what I'm getting at is that this document goes into too little detail, it has a number
of inaccuracies in it, particularly in regard to cleanup levels. And this really needs to
be resolved and we need to have these addressed properly so that human health is
protected. As it is it's just not acceptable.
Under perchlorate, there you have it as being .6 milligrams as being the soil cleanup
level for the protection of groundwater and the cleanup level that was actually in the
RI for the protection of groundwater is .06 or 60 micrograms or .06 mg/kg. Now, on
the basis of that .06 the CAG had calculated a hazard index of 55 for perchlorate to
home gardening, in terms of the consumption of vegetables, okay. That would be
assuming that you would have about 50 percent other soil amendments brought in,
okay. And yet, you know, it talks in here about cleaning up to a hazard of not greater
than one. Well that's much, much higher. That's assuming at .06. At .6 it would be a
hazard of 550, okay, which is really not acceptable.
The proposed cleanup level for the protection of groundwater was incorrectly
listed in the proposed plan, and a corrected version of Table 2 was issued to
provide the corrected levels. Please see the response to CAG written comment 10
regarding perchlorate in home-grown produce.
EPA notes the referenced DTSC import fill guidance specifies best practices for
soils imported to school sites. EPA does not consider this to be an ARAR for the
OU-6 cleanup and will not require special procedures for soils removed from
areas of OU-6 that are suitable for unrestricted reuse.
The PP is a summary of EPA's evaluation of OU-6 and the presentation of the
Preferred Alternative. As a summary document, some information is
incorporated into the plan as part of the Administrative Record that forms the
basis for EPA's decision at this site.
The TPH screening level was corrected to 100 in the revised proposed plan
Table 2a.
EC is the selected remedy for areas containing COCs in soil at levels that present
an unacceptable risk for unrestricted reuse will be set forth in detail as part of the
RD. Restrictions will include provisions for managing excavation and movement
of these soils to ensure they are handled appropriately. These restrictions would
include sampling and notification requirements if soils are moved.
The cleanup levels have been updated further since the Proposed Plan and are
shown in Table 2-2 and 2-3 of the ROD.
3 OF 26
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Appendix E-l. Public Meeting Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from the Community Advisory Group
Comment # Comment Response
And furthermore, this is going to affect not only areas that might be used for
residential use on the Aerojet site but any soils that might be exported, let's say once
an area is approved for use, they might be exported elsewhere. So I think we really
have a problem and I'm really against having soils being exported elsewhere. If you
look at the DTSC 2001 clean import fill guidance, it says very specifically that
import fill should not be coming from cleanup sites, from contaminated sites.
6.
Commenter: Mr. Allen Tsao
I have a lot of comments but I just want to preface it that these comments are geared
toward the general readability of the document, the proposed plan.
[a] The proposed plan covers over 50 sites, 78 to be exact by my count of Table 1,
the number of remedial action areas. There's separate and individual EPA-preferred
alternatives for each of these remedial action areas but Table 3 doesn't specifically tie
it to any single remedial action areas. In other words, you need to run the nine NCP
criteria against each of these remedial action areas for the general public to
understand and make some sense and provide some meaningful recommendation or
concurrence inaton [inaudible] the EPA's recommended plan.
Let me put it in a more concrete way. When you have a proposed plan for a remedial
action area and the proposed plan is to do Alternative X, we cannot tell what the
other potential, viable alternatives are. It is really difficult in this proposed plan
because I can't tell, there is no table for it. I can't tell what the cost of the remedy will
be had there been an IC or what the cost would be had there been soil vapor
extraction plus soil excavation versus capping. There is no way for me to be able to
tell. Hie only table that provides the cost is on one table that lumps everything
together into three or four different groups. So for me and I believe other members of
the public to make a meaningful comparison, there is no way for us to tell whether,
you know, for example, $2 million for excavation is worth it, versus $2.5 million for
capping. I can't make a I can't make a meaningful recommendation without that
information.
I strongly recommend EPA to provide each table, a table of alternatives for each
remedial action area based on the reason I just stated. And also break this proposed
plan into smaller proposed plans because there are over 78 remedial action areas. It's
just I think it's you're asking the public too much. By putting this proposed plan
in front of them and asking them to make some sensible and meaningful comments
is just I don't think it's doable and I think you're asking them too much for it. So I
would strongly recommend that we break this proposed plan up to smaller pieces and
that way we can look at each of the remedial action areas or each four or live
management areas. It just makes it easier that way.
[a] The Proposed Plan is a summary of the Preferred Alternatives for OU-6.
Because this OU is a complex component of a large NPL site, it is impractical to
include a specific evaluation of every remedial action area in the PP while
retaining the summary nature of the proposed plan. Detailed information on the
development and screening of Alternatives was presented in the FS, part of the
Administrative Record supporting EPA's decision for this site.
In particular, Table 6-3 in the FS report provides detailed cost estimates for each
Alternative as it would be applied to each Remedial Action Area. The entire
Aerojet Superfund site has been divided into nine Operable Units (OUs) to
manage the investigation and remediation of the site in accordance with the
Partial Consent Decree, and EPA is managing the selection of remedies on an
OU-by-OU basis. As with the prior OU-3 and OU-5 Proposed Plans, it is
necessary to group the remedial areas throughout OU-6 into a single Proposed
Plan.
[b] EPA provided information on the definitions of technical terms within the
Proposed Plan but understands that additional definitions would be helpful.
While these technologies were defined in the FS report included in the
Administrative Records, EPA will consider defining additional technical terms in
future Proposed Plans.
[c] The table of Proposed Actions [Table 1] in the Proposed Plan includes the
planned use for a given remedial action area. The Preferred Alternative in the
proposed plan includes a cleanup level consistent with the future land use
presented. The "SLERA ESL" column presented proposed cleanup levels
protective of ecological receptors. The cleanup levels adopted in the ROD for
those areas requiring cleanup to protect ecological receptors are detailed in the
ROD Tables 2-2 and 2-3.
[d] The Human Health Risk Assessment used sampling results on the nature and
extent of potential contaminants of concern to conduct a conservative, point-by-
point risk assessment at each sampling location. This information was presented
in graphical and tabular form in the HHRA, showing those areas that presented a
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Comment # Comment Response
potential risk to human health under residential/unrestricted or
commercial/industrial exposure scenarios.
[b] Other readability issues. I would strongly recommend that EPA add additional
technical terms in the glossary. For example, soil flushing, mixed use. Define soil
flushing, define mixed use, define institutional control, define operational controls.
Those are a few examples. These came up when I was talking with Janis Heple, our
Chairwoman, who had different ideas on what institutional control is. And we are
both college graduates. If we had this misunderstanding on what those are I believe
other people would too. And bold those terms that are in the glossary, it just makes it
for easier reading of this complex proposed plan.
[c] Another readability issue. It is not clear in Tables 2a and 2b, which cleanup level
were referred will be used. And I think Jimmy Spearow touched on that. Because
for any given chemical there could be like three or four cleanup levels. It's really
difficult to be able to tell which cleanup level is being used for the specific remedial
action area.
And by the way, the ecological number, it is not clear to me that those numbers
under SLERA, S-L-E-R-A, ESL column, are those cleanup numbers for eco-
receptors? It doesn't say "cleanup level" as opposed to other columns where it says
specifically "soil cleanup levels." So it's not clear whether those would be cleanup
levels.
[d] Okay. And so and also page 13 on the proposed plan. The second bullet item it
states:
"If eco risk exceeded screening levels and the Screening Level Eco Risk
Assessment recommended further evaluation for an action, then the area was
recommended for cleanup."
Okay, that's an accent, I understand accents. The bullet right above that states:
"If the potential human health risk was just above 1 x 10-6, the HI was greater
than 1.0, or an estimated blood lead level was great than 10 micrograms per
deciliter, then the area may have been recommended for cleanup evaluation."
So does this mean that the area may not have been recommended for evaluation as
well? It's not clear. And the same thing for the third bullet on page 13.
[e] This is a general comment. There is no lat/long on the maps. George Waetell,
that's spelled G-E-O-R-G-E, W-A-E-T-E-L-L and I, and especially George,
requested the lat/long information be posted on all maps. The EPA promised to have
this information on the maps but to this day there is no lat/long on any of the figures.
Please put the lat/long information on the figures.
[e] EPA recognizes the need for detailed coordinates and attempted to balance
readability of the figures and clarity given the size limitations of the Proposed
Plan. A key figure in the ROD, Figure 2-2, has latitude and longitude information
to assist the reader.
[f] EPA appreciates the comment and notes that soil and sediment were evaluated
in the OU-6 RI and risk assessment. Therefore, the ROD does note that the soil
cleanup levels for protection of human health and ecological receptors also apply
to sediments in those areas where a remedial action is being taken (see Footnote a
on Table 2-2).
[g] Institutional Controls do not reduce toxicity, mobility or volume through
treatment. This component of the OU-6 preferred alternatives was presented in
the Proposed Plan for those areas where ICs are required as a portion of the
remedy for prevention of exposure to contamination that remains in place. While
the preference for treatment was considered in the Selected Remedy, ICs were
selected for contamination where ICs best met the NCP criteria. These include
areas of groundwater contamination through OU-6 which are being addressed
under other OUs at the Aerojet Site. These ICs will be emplaced using Land Use
Covenants administered by the DTSC.
[h] the HHRA evaluated risks to potential future residential or unrestricted use
for all management areas in the BOU. Hie PP Table was intended to identify a
summary of planned future uses for individual remedial areas to aid the reader.
There was not a separate exposure pathway or scenarios identified for mixed use
areas.
[i] EPA expects the completion of SVE remedies before making property
available for unrestricted reuse. All remedial system components (such as SVE
well, piping, and treatment systems) will be expected to operate effectively and
without interference from development or unacceptable exposures to site
occupants. This approach will be clarified in the Remedial Design that follows
the ROD and lays out the specific approach and sequencing for remediation.
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[f] On page 14, Remedial Action Objectives. First bullet:
"Prevent exposure to COCs in soils that pose an unacceptable risk for present
and future workers and residents on the property and ecological receptors on
the property."
Please add "sediment" in addition to soils. Because clearly for the Buffalo Creek area
the sediment in the creek are being cleaned up.
Also please extend your wording not just on the property but off-property as well
because contaminants may very well have migrated off-property.
A related comment to that is that this proposed plan doesn't address potential
contaminants that may migrate off-property and contaminants that may migrate on to
OU-6 from Island OU or other areas.
[g] Page 16, Table 1. I'm sorry, that's page 16, Table 3. Under Alternative 2,
Institutional Controls. It indicates in this table that this particular alternative does not
reduce toxicity, mobility or volume through treatment. So therefore I don't see why
this alternative is being proposed for some of the remedial action areas. I do not
support this alternative for any of the remedial action areas.
[h] Going back to Table 1. Please explain the difference between commercial versus
industrial versus mixed use and residential in terms of exposure scenario for human
receptors.
[i] And a final comment is that it does not appear that the proposed some of the
proposed actions by EPA are protective, especially those that are proposed for
Alternative 2 as well as Alternative 4. Specifically, those are proposed for doing soil
vapor extraction under a mixed use or residential use. If I were to buy homes I would
be concerned about having pipes underneath my property and having it run. And if
that is not the case please, please do indicate so. Because it sounded like from earlier
discussion that the cleanup will be done using SVE. Until then, residents won't be
able to build houses. But as it stands right now the proposed plan does not
accommodate that since appropriate it tells me that when I buy property in the
areas that that's designated as mixed use or residential, there will be, depending on
where we are, the remedial action area that will be source vapor extraction
equipment. Thank you.
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7.
Commenter: Ms. Alta Tura
Habitat 2020 and ECOS have taken a look at the proposed plan and feel that the
summary is not adequate, more information is needed. We are particularly interested
in knowing how the proposed cleanup relates to the planned land uses. We want to
see information on the levels of concentration of the chemicals of concern and more
time is needed to review the plan. Thank you.
EPA extended the Public Comment period on this proposed plan to September
20,2013 in order to afford the public additional time for review. The complete
RI, Human Health Risk Assessment, and Ecological Risk Assessment were made
available as part of the Administrative Record for the OU-6 proposed plan for
review by interested members of the public. In addition, EPA provided technical
support through the Technical Assistance for Superfund Communities (TASC)
program from .Time through September 2013 to provide additional information
and clarity regarding information in the PP and Administrative Record. The
Selected Remedy for OU-6, and detailed in the ROD, includes cleanup that
supports the future land use in each areas. Future land uses were determined in
accordance with EPA's land use directive, and assessed in a Reuse Assessment
performed in 2010.
8.
Commenter: Ms. Janis Heple
I just I wanted to come up and be able to see everybody when I spoke because in
reviewing this plan I really concur with the comments that have been made by the
other speakers that there just isn't enough information for us here to really be able to
speak out on this plan, except perhaps not in support of it.
Allen mentioned 78 areas, remedial action areas. I for some reason had counted 75.
But then it's further kind of grouped into 16 management areas and then one of those
management areas is pulled out into three parts, the Admin area. They all need a
much more complete presentation in order for the community to be able to weigh in
on their cleanup.
And also more time. I mean, we just have until June 7tli right now and we really
don't have the information that we would need at this point in time. Even I know
that we have the information from the remedial investigation feasibility study and I
know that we've had six or so meetings that involved discussions of the Operational
Unit 6. However, those meetings never really got to what we're now seeing glimpses
of in this proposed plan information.
I went back and kind of purposefully looked at some of your presentations, Gary.
It's like, was I, you know, was I missing tilings? But actually we just didn't really
have the information that was going to tell us what would actually be happening if
this proposed plan was to move forward.
And I'm glad that we were able to make some of the comments that we did make last
year, the letter that we wrote in July from the CAG. But, you know, now there's a
real sense of criticalness about this issue. The objective for the OU-6 remedy is to do
no harm to future owners of the land to be developed, based on what I believe is a
one in a million risk for residential or unrestricted use. And given the multiple
EPA considered public input regarding the complexity of OU-6 and extended the
end of the public comment period on the PP from .Time 7,2013 until September
20,2013. While EPA presented on the OU-6 FS and Proposed Plan at the
December 2012, January 2013, and April 2013 CAG meetings, EPA agreed with
the commenter that additional time and resources were needed for the public to
interpret the information in the Proposed Plan and make meaningful comments.
EPA provided technical assistance to the CAG using EPA's Technical Assistance
to Superfund Communities (TASC) program. The assistance included
discussions with CAG members through the summer, and presentations of
specific information requested at the July and September CAG meetings.
Recognizing that the full Administrative Record for the site incorporated into the
OU-6 Proposed Plan by reference is very large, the technical assistance expanded
on the explanation of remedial technologies included in the proposed plan, such
as soil vapor extraction, soil flushing, and air stripping. The TASC contractor
also provided extensive support regarding the institutional and engineering
controls used to mitigate potential risk from vapor intrusion.
EPA notes the commenter's support for source removal as a component of the
Selected Remedy for OU-6. The Selected Remedy for OU-6 is required to be
protective into the future as long as waste remains at the site at levels not suitable
for unrestricted use. The protectiveness of this remedy will be evaluated every
Five Years as required by statute, and this evaluation will include an analysis of
changes hi regulatory standards for the COCs at the site. If a Five Year Review
identifies problems with the protectiveness of the remedy for OU-6,
recommendations will be made, tracked, and implemented to ensure
protectiveness.
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tity Advisory (
it
contaminations and continuing technical and scientific improvements that will
change the risk assessment over the 100-plus years length of the remedy, the CAG
feels strongly that it is critical that the remedy is reasonably conservative. Because if
it can go wrong, it will go wrong.
We discussed at one of the meetings on the IRCTS, the other hazardous waste site
nearby, we discussed something came up about, oh, well we're only planning for
the next 30 years. And as you might remember if you were there, and most of you
were, I was somewhat incensed because I have been involved working on this site
for 34 years at this point. And 30 years is nothing when it comes to these sites. And
what I think those of us on the CAG are concerned about is the degree to which these
remedies will be put in place and will be carefully followed. And if there's people in
homes who have vapor extraction systems underneath their residences and they're
not I mean, I'm very, very concerned. It's like it's raised the bar. We're not just
dealing with cleanup, we're dealing with this potential movement of citizens onto this
property and I feel a real heavy responsibility over that issue.
The CAG supports source reduction removal to the maximum extent possible in
OU-6. This will reduce OU-3 and OU-5 operation time and be protective of human
health.
Alternative 4, you know, talked about on page 16, only partially meets this criteria.
Now we have had some discussions on that tonight and I may have been
misinterpreting. Again there is a need for more in-depth information. I may have
been misinterpreting some of the way that that was intended when it talked about a
partial remedy. But it's mentioned that the soil vapor extraction is listed to partially
meet the need for reduction of toxicity mobility or volume through treatment. And I
guess this was asked earlier tonight, what remedy would fully meet the need for
treatment of contamination.
And then I believe Allen mentioned that the proposed plan does not define the
remedy terms for air stripping and the flushing that are mentioned in the selected
remedy sites. So we do want to have an explanation of these, the terms. And also the
combination of using the soil vapor extraction, the air stripping and the flushing
together to meet the remedy objectives.
I am not positive, again, because the information is slim here. And of course you
guys all know how big the RIFS is. We really needed a bigger volume. Seventeen
pages just really isn't enough for the magnitude, the 75, 78, whatever it is, the entire
number of sites that we're dealing with here.
The Five Year Review is in addition to the requirement for effective operation
and maintenance of any systems installed as part of the OU-6 remedy. An
operation and maintenance plan will be required as part of the Remedial Design
that will follow this ROD. The plan will include requirements to inspect,
maintain, and operate remedial systems including those for vapor mitigation.
The controls selected in the OU-6 ROD to prevent exposure to contaminated
groundwater and unacceptable risk from vapor intrusion from groundwater
beneath OU-6 will be effective. This remedy will manage potential risk posed by
sources in other operable units (such as OU-7) to protect site occupants in OU-6.
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Comment #
Comment
Response
But in terms of the institutional controls, how are they fully protective of human
health for the six areas listed in the proposed plan? Hie six areas include two
commercial areas, two of mixed use, one of residential and one industrial site. And
it's a little confusing in reading the document because in the Summary of Remedial
Alternatives listing it mentions Alternative 2 as not acceptable for family homes, day
care centers, health care centers or schools. But in the selected remedy table, Table 1,
Alternative 2 is listed as the remedy for mixed designated sites AW-SV-R-1, L2-SV-
1 and residential designation L5-SV-R-3. We need a much better explanation of how
the criteria becomes acceptable as a stand-alone remedy.
Earlier Jimmy talked about the source areas, predominantly, I believe, in OU-7. If
development of the Easton and Westborough areas was to move forward as soon as
this cleanup remedy, if you guys were to move forward against the way the
community is feeling right now and start getting cleanup going and then it you
know, development would follow on the heels of that, it would be placing residents
over the groundwater contamination that has still not been addressed that is moving
out of OU-7, out of the major source area. Thank you.
9.
Commenter: Mr. Burt Hodges
At the end with respect to the deadline for comments being June the 7th. My concern
is with respect to the CAG membership. The next meeting of CAG isn't until July.
And I guess echoing Janis' comments about time to consider tilings and have some
additional information as others members of the CAG have talked about here, to
consider. I would my comment is that June 7th is too early. It seems to me as a
member of the CAG I wouldn't be prepared to feel I could add anything significant
as a comment now until I learned more from the CAG members, such as after the
next at least after the next CAG meeting. So I would propose that your deadline
really ought to be, say, August instead of June. So that's my comment, I think it's too
early.
EPA considered public response to the PP and extended the public comment
period to September 20,2013. The extended deadline allowed two CAG
meetings for additional discussion of the PP prior to the extended comment
deadline. EPA also provided resources through the Technical Assistance for
Superfund Communities (TASC) program for direct support to the CAG in
interpreting the PP and developing comments.
10.
Commenter: Mr. Allen Tsao
I just wanted to add that I had commented earlier to break the proposed plan into
smaller pieces and add more information to it. Now if that proposal is not acceptable
by EPA please let me know right away because I know that our oral comments and
written comments won't be responded to until the ROD is signed. So if that is not a
viable option I would like to know as soon as EPA can tell that. Thank you.
EPA considered public response to the PP and extended the public comment
period to September 20,2013. The extended deadline allowed two CAG
meetings for additional discussion of the PP prior to the extended comment
deadline. EPA also provided resources through the Technical Assistance for
Superfund Communities (TASC) program for direct support to the CAG in
interpreting the PP and developing comments.
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Comment #
Comment
Response
11.
Commenter: Mr. Burt Hodges
Just to add a little bit to my previous comment about thinking that there really ought
to be a delay until for your deadline on comments to tilings. Part of my request
would be with respect to Save the American River Association, which we have
commented previously with respect to the residential development and tilings. And
part of my comments related to giving the rest of our Save the American River
Association Board time to consider whether they wanted to make additional
comments to something like this. June the 7th would be too early for that to be
accomplished.
EPA considered public response to the PP and extended the public comment
period to September 20,2013. Hie extended deadline allowed two CAG
meetings for additional discussion of the PP prior to the extended comment
deadline. EPA also provided resources through the Technical Assistance for
Superfimd Communities (TASC) program for direct support to the CAG in
interpreting the PP and developing comments.
12.
Commenter: Mr. Jimmy Spearow
Just to follow up on my comment. On Table 2a there really needs to be the
concentration of contaminants presented there, both the exposure point of
concentrations that have been presented. And it needs to be for each of the different
exposure units, okay. For example, if you've got a region that's going to be
residential where you are going to have, say, a lot size of an eighth of an acre or so,
it's the exposure point concentration of percent UCL that would be within that
exposure unit that would be present there. And there just really isn't space for that
here, okay. And there really needs to be for you to understand the contaminants that
different receptors could be exposed to, whether it be residential receptors or
industrial or aquatic receptors that are present there. That's, I think, an important
tiling that we need a lot more information and needs to be expanded because you
have so many different exposure units and so many different areas that are being
addressed in the site.
Table 2a presented the proposed cleanup levels for non-VOCs in soils in OU-6,
and the ROD Tables 2-2 and 2-3 specifies the selected cleanup levels. The
remedial design will specify how the cleanup goals, selected in this ROD, will be
achieved. The remedial actions will then be evaluated to ensure they achieve the
cleanup levels selected in the ROD.
13.
Commenter: Mr. Allen Tsao
I wanted to just add on to Jimmy's comment that I agree with Jimmy's comments.
It is not unusual to have a concentration, maximum concentration, a 95 UCL
concentration in the proposed plan. I'm pulling a proposed plan from Moffett
Airfield, Site 26 from the Navy, and it's a joint I believe it's a joint proposed plan
from the Navy and EPA and they have a table of their concentrations in the proposed
plan.
Individual remedial action area risks are summarized in the Proposed Plan Table
1 for brevity, presenting the COCs and pathways driving risk. The OU-6 Human
Health Risk Assessment, incorporated into the Proposed Plan by reference,
presents the numeric risk characterization for each individual area in detail.
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Comment #
Comment
Response
14.
Commenter: Mr. Jimmy Spearow
Previously the CAG has asked for the contaminants concentration in the Islands so
this is the region that the contaminants would be migrating from. And without that
information it's hard to evaluate what the real risk would be over time to the
Boundary operational unit and the receptors in that. And not just the contaminants
but also the migration of groundwater and also the contaminant failure.
Until those are provided it's really hard to evaluate the, I'm going to say, future risk
to the Boundary operational unit in terms of the receptors that would be there. So I
think that really needs to be included in order to look at this. Here again we need to
think about or the proposed plan needs to think about coupling the cleanup to other
upstream source areas that are still releasing contaminants. Thank you.
While the RI for the Island OU is currently in preparation, soil and groundwater
data have been collected from these areas to characterize the nature and extent of
contamination. These data are incorporated into annual plume maps provided by
Aerojet to the Agencies, and EPA has combined these individual plumes into a
composite plume map that is provided at EPA's Aerojet Site Page and routinely
to the CAG. Detailed plume maps are also included in Appendix A of this ROD.
The contamination present in the Islands OU that could potentially migrate to
OU-6 through the groundwater pathway is subject to regular groundwater
monitoring and an annual effectiveness evaluation of current OU-3 and OU-5
remedial systems. The institutional controls that are a part of the OU-5 ROD will
protect receptors from contamination migrating from the Island OU.
Aerojet is currently preparing the final Island OU-7 RI report and EPA
anticipates the CAG's review of this document in the near future.
Written Comments submitted by the CAG on the Proposed Plan for the OU-6 Cleanup (Comments dated September 20, 2013)
1.
The CAG recommends that development on land in OU-6 (also known as the
Boundary OU) continue to be restricted until the public processes for
Operational Units with plumes extending under OU-6 have been completed and
any related institutional controls addressing ground water vapor are in place.
A. Given that the Remedial Investigation/Feasibility Study (RI/FS), Risk
Assessment and Proposed Plans for other OUs have not yet been through a
public vetting process, selecting a remedial alternative for OU6 appears to be
premature. The OU6 Proposed Plan does not adequately disclose that EPA
proposes to permit residential use in OU6 in areas subject to the migration of
contaminated groundwater from other OUs.
Aerojet entered into a Partial Consent Decree with EPA, the RWQCB, and the
Department of Health Services in 1989 to meet Superfund cleanup obligations.
The Proposed Plan notes "The cleanup will also prevent COCs in Boundary OU
soil sources from migrating to groundwater, and provide controls to prevent
exposure to VOCs volatilizing from groundwater that is being cleaned up as a
part of other OUs." The preferred alternative to address potential exposure above
groundwater plumes migrating from other OUs is through the use of Institutional
Controls that will require engineering control measures to prevent exposure.
These areas are shown on Figures 3 through 5 as part of the preferred alternative.
The preferred alternative accords with the reasonably anticipated future land use
for OU-6. The Reuse Assessment, included in the proposed plan as part of the
administrative record, provides further details regarding the land planning
process undertaken by the property owner and local reuse authorities.
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Comment #
Comment
Response
B. It is also unclear in reading the Proposed Plan, whether EPA would allow
engineering controls, such as vapor mitigation/barriers (Alternative 3), as either a
stand-alone or part of another alternative in residential areas. If EPA were to
allow residential homes to be built with engineering controls (Alternative 3), we
do not believe this is disclosed in the Proposed Plan. Because such engineering
control is not disclosed in the Proposed Plan, the CAG believes that the EPA
should seriously consider vetting this proposal formally with the public, per
CERCLA requirements.
EPA discussed the proposed plan at the two CAG meetings preceding the public
meeting for the PP. The meetings included attendance by Dr. Dan Stralka,
regional toxicologist of EPA. At these meetings, discussion included the use of
engineering controls in residential areas where there is a potential risk from
vapor intrusion from groundwater into structures.
C. Hie OU6 Proposed Plan does not adequately disclose the extent of the
institutional controls intended to address groundwater vapor (due to an omission
connecting Remedial Action Areas in Table 1 to Figures 3 and 4).
The proposed plan describes the preferred alternative to include ICs and
engineering controls to prevent migration of VOCs into indoor air above those
areas of impacted groundwater with potential vapor intrusion concern. The extent
of these controls will be defined in the remedial design, and are shown in ROD
Figures 2-23 to 2-31.
D. The Proposed Plan does not provide the clean-up levels for soil vapor. It appears
that if EPA selects the engineering control to reduce or prevent human exposure
to contaminated vapors that may be present in existing or future commercial-use
buildings, cleanup levels for soil vapor has to be presented in the Proposed Plan
and the ROD.
Table 2 of the proposed plan presented target ambient air risk levels; the
performance of SVE for remediation will be assessed using soil gas samples
collected at a range of depths. The results of these samples will be adjusted using
site specific-depth and attenuation factors to ensure the ambient air VOC cleanup
levels will be met. This is the approach being used in the OU-5 cleanup at the
site, currently in progress.
E. The proposed plan has also not considered the potential for groundwater with
elevated levels of TCE migrating from OU9 (and other OUs) into OU6, or from
its current location in OU6 further down gradient in OU6. For example,
Boundary OUFeasibility Study figure 6-1 (September, 2012) shows TCE
isoconcentrations exceeding 500 jug/L in groundwater in OU6 - Line 2, as well
as further to the south in OU9. The proposed plan has considered institutional
controls, including restricting residential use or requiring vapor barrier/subslab
vapor mitigation system for regions currently exceeding 11 jug/L TCE in
groundwater, and the CAG strongly supports these institutional controls.
However, Skeo-Solutions Figure "Recommended Remedial Alternative and
Proposed Residential Land Use Alternatives - Buffalo Creek, Line 2, Line 5 and
West Lakes Open Space Areas" and Proposed Plan Figure 4, show several
regions proposed for Low, Medium or High Density Residential use in Line 5,
OS-7, OS-6 and OS-5 where institutional controls would not be required. Many
of these regions seem to be downgradient of TCE plumes.
The Proposed Plan included a preferred alternative of institutional and
engineering controls to prevent migration of VOCs into indoor air until
groundwater is remediated under other operable units. The Selected Remedy
defines the areas subject to these controls, based on groundwater monitoring data
that extend back to the early 1980s. Regular groundwater monitoring has defined
the location of plumes in groundwater, and this information was used in the
proposed plan to show the areas where vapor intrusion potential risk exists. The
ROD selects these controls, and the extent of these controls is shown on Figures
2-23 to 2-31. Groundwater will continue to be monitored, and the performance of
these controls will be evaluated to ensure they are protective. The plumes are not
currently shown to be expanding, but sitewide monitoring will continue to ensure
the remedy remains protective. The performance of the entire OU-6 remedy will
be reviewed every five years to ensure it remains protective, and legal
enforcement instruments will be created to ensure this remains the case.
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Responses to Comments from the Community Advisory Group
Comment # Comment Response
These groundwater TCE plumes are migrating and will need to be addressed for
approximately 200 years. Although Aerojet and EPA are currently working to
address TCE and other groundwater contaminant plumes, the CAG is concerned
that the commitment for funding and effort may not continue for the lengthy
time needed to remediate these plumes. Since the eventual extent of the TCE
plume cannot be entirely predicted, the CAG is concerned that institutional
controls are not being required for all of the residential use regions that are down
gradient of TCE plumes with substantially greater than 11 jug/L TCE.
Since the eventual extent of the TCE groundwater plumes cannot be fully
predicted, the CAG recommends greatly expanding the regions where residential
use structures in OU6 would be required to have engineering controls or systems
to prevent vapor intrusion, e.g. at least a vapor membrane and a passive subslab
depressurization/venting system (that could be converted to an active system if
needed at a later date).
Since the eventual extent of the TCE groundwater plumes cannot be fully
predicted, the CAG recommends greatly expanding the regions where residential
use structures in OU6 would be required to have engineering controls or systems
to prevent vapor intrusion, e.g. at least a vapor membrane and a passive subslab
depressurization/venting system (that could be converted to an active system if
needed at a later date).
2.
The CAG recommends prohibiting residential developments on areas where
SVE remedies will be operational until SVE is complete.
The remedy selected, particularly the SVE remedy, for Mixed Use and Residential
Area needs to have more explanation. Would the EPA allow buildings such as
housing to be built on top of SVE systems or would there be land use restrictions
where no buildings can be built until the SVE remedy is considered complete and
meets the Remedial Action Objectives (RAOs) for VOCs for the specified land use?
Either way, this has to be explained because many community members interpret
this SVE system to be built in a way that would allow buildings constructed on top
of the SVE system and this would include housing units. The CAG does not support
SVE systems in operation or retained as a backup with housing units. Hie self-
monitoring program seems extremely complex and invites strong conflicts of interest
for the housing association or the home-owners or its contractors. The CAG urges
the US EPA and DTSC to not allow residences to be built in the proximity of SVE
remedy systems due to potential contaminants in SVE effluents.
EPA expects the active portion of an SVE remedy will be completed in areas
planned for residential use prior to development. Appropriate monitoring and
land use covenants are required for either residential or commercial use of BOU
locations until the potential threat of vapor intrusion is removed.
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Responses to Comments from the Community Advisory Group
Comment # Comment Response
3.
Lands redeveloped in OU6 should have deed restrictions to prevent human
exposure to groundwater. These restrictions would specifically prevent wells for
drinking water or be used in a way that would be a potentially complete
exposure pathway for human or wildlife.
There should be a deed restriction in all areas of OU6 to prevent people from digging
a well for drinking and irrigation purposes. The contamination in OU6 is well
documented and there should be a deed restriction for the use of groundwater for the
purpose of health protectiveness. There may be a restriction to prevent groundwater
for drinking and irrigation due to other reasons; however, the deed restriction should
be specifically to prevent humans and/or wildlife from exposed to groundwater.
Hie OU-6 ROD describes the groundwater ICs that are applicable to OU-6,
which include restrictions on well installation to prevent exposure to
contaminated drinking water and/or interference with the groundwater remedy.
4.
The following sites that are designated as "Areas Not Retained" must be
evaluated fully for remedial action. The CAG's understanding in allowing these
sites as "Areas Not Retained" means that no further action and, therefore, no
ICs or other remedial action will be taken. This designation is unacceptable
unless the risk is at the low end of the 10-6 to 10-4 cancer risk management
range and that the lateral and vertical extent of contaminants are well
characterized.
The following six Remedial Area Number that Aerojet has categorized for no further
action (No Action Sites) are as follows:
AE-N-10 Ok, with no remedy. PCBs in shallow soil only, not at 11 feet bgs.
AW-N-11 captured under AW-R-3
AW-N17 overlaps with AW-R-3 with same COCs so it will be addressed.
AW-N-18 added to AW-R-6 and AW-R-10 so it will be addressed
DPEB-N-2 captured under DPEB-R-1
DPEB-N-3 same as above.
The reasons for no further action for these sites is because Aerojet believes the
likelihood for residential re-use is low and therefore, Aerojet believes that no further
action is necessary.
Some of the areas identified as 'Not Retained" received this designation because
these smaller areas of contamination overlap or were within other areas retained
for evaluation and remediation. In these cases, the COCs presenting possible
risks from these areas were captured using the identifier of the retained area(s).
Details of this evaluation are documented in a series of tables in Section 1 of the
FS.
All areas of OU-6 overlying groundwater contamination, including the non-
retained areas, will be, at a minimum, included within the groundwater ICs that
prohibit use of groundwater (see Section 1.2 of this ROD for more details).
AE-N-10: This location will be encompassed by ICs limited future use to
industrial or commercial
AW-N-11: This location is included within Remedial Area AW-R-7/R-14
AW-N-17: This location was not retained for further action due to low
concentration, small volume, and low risk. However, the adjacent AW-R-
4/R-5 area may include this general area, once the design and remedial area
has been established.
AW-N-18: This location is included within AW-R-6 and AW-R-8/R-9/R-
10/R-12/R-13, and contamination will be addressed in the selected remedy.
DPEB-N-2 and DPEB-N-3: These locations are captured within Remedial
Area DPEB-R-1.
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Responses to Comments from the Community Advisory Group
Comment #
Comment
Response
A. We echo's US EPA's comments made in the FS (see p. 314 of 414, Final OU6
FS, US EPA's Specific Comment 21) that the anticipated or likely future use of
an area should not be used to support a "not retained" designation (as for not
retained for feasibility of cleanup analysis) because future use can change;
furthermore, contamination appears to exceed unrestricted use (as an example,
see Figure 1-31 of the FS for the Dredge Pit and Eastern Basin-also designated
as DPEB-N-2 and DPEB-N-3).
The referenced EPA comment on the OU-6 FS reflects EPA's position that
anticipated future use alone should not be used as the sole determinant of
remedial evaluation and action. For those areas where COCs will remain at levels
that present an unacceptable risk for unrestricted use, the selected remedy
requires ICs that prohibit sensitive uses.
B. In response to US EPA's comment, Aerojet replied that "As Aerojet plans to
continue doing business at this location into the future, we believe that these
statements are appropriate and should remain. Institutional Controls will be in
place to prevent inappropriate use in the future including deed restrictions."
Aerojet continues, "Aerojet will prepare figures identifying areas with deed
restrictions or other institutional controls. Aerojet's Site Remediation Group
reviews and approves all authorization requests for soil excavation or building
demolitions. Hie review of these figures will be included in existing and future
authorizations requests." Although US EPA appears to be satisfied with this
response, the CAG finds the response from Aerojet unacceptable for the
following reasons:
i. It seems the "future authorizations requests" would be seeking authorization
from tlie Aerojet Remediation Group and not subject to review by state or
federal agencies.
ii. The Institutional Controls and deed restrictions mentioned in the quoted text
above does not appear in the proposed plan for those 6 sites.
iii. No regulatory oversight is provided on the Aerojet's Remediation Group,
and as such those decisions made by Aerojet regarding those 6 sites
circumvents the CERCLA process. CERCLA requires that the 9 NCP criteria
must be considered. Such consideration includes formally solicit public
comments and evaluation of remedial alternatives. Without proper regulatory
oversight, CAG finds it difficult to accept those 6 sites as protective.
ICs required as part of the OU-6 selected remedy will include provisions that
future use be restricted in accordance with a Land Use Covenant developed with
DTSC. EPA concurs that review by the PRPs site remediation group does not
constitute an enforceable IC. The six sites identified earlier in this comment are
being addressed through remedial actions described earlier in the response to this
comment.
C. Aerojet states that leaving those 6 sites outside the Feasibility consideration is
because the re-use of the sites is very low. And claims that".. .If reused, the area
of this sample location will be backfilled, which will remove the exposure
pathway." Aerojet does not specify the amount or extent of backfill and how the
integrity of the backfill material will remain in place. Simply put, there is no
regulatory oversight in areas that receive "not retained" designation since the
area exits the CERCLA process; in fact, it receives an "unrestricted use"
designation. This type of "remedy" in not protective of the human health,
The six sites identified earlier in this comment are being addressed through
remedial actions described earlier in the response to this comment.
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Responses to Comments from the Community Advisory Group
Comment # Comment Response
commercial or residential or suitable for building schools. Under the current
proposal, the soil there can be moved without any restriction and re-used for
other proposes.
D. Are there any other sites like those mentioned above that receive a "not retained"
designation because future residential use is highly unlikely? Please provide a
list of additional sites that falls under this category. Hie CAG strongly
recommends that the EPA and State regulators provide additional information to
support these locations as areas "not retained" for feasibility study.
No sites were designated "not retained" because future use was unlikely. EPA
considered reasonably anticipated future land use for the entire OU-6. Areas
where COCs remain at levels that present unacceptable risks for future
unrestricted use are identified as remedial action areas where a remedy was
selected to prevent or eliminate such exposures.
5.
The CAG recommends the US EPA and state regulatory agencies conduct a
post-removal ERA to adequately capture the extent of contamination, including
areas offsite, and determine whether additional action is needed.
The following two sites are the subject of the comments that follows:
AE-C-1
Buffalo Creek
Aerojet states that a removal action completion was conducted in 2010 to achieve its
Time-Critical Removal Action (TCRA). Please note that a TCRA does not
necessarily need to achieve preliminary remedial cleanup goals (PRGs). It is unclear
to the CAG what was the removal action goal in 2010, and whether the PRGs would
be the same as the removal action goals (side note: removal action goals are often
much higher than the remedial cleanup goal). While it is possible that the TCRA
confirmation sampling result meet the preliminary remedial action goal, the FS lacks
detail on whether areas outside the excavation have been sufficiently delineated and
meet the PRGs. It appears that a post-removal action ecological risk assessment
(ERA) would be needed in order to make this determination. Without a post-removal
action ERA, we think it's premature to draw a no further action conclusion.
The August 2009 Proposed Plan for the Perimeter Groundwater OU of the site
included a proposed remedy of soil excavation to remediate PCBs and metals in
the 10(D) and 11(D) source areas.
Review of the comments received during the public comment period did not
identify any comments that would change the proposed action to remove soil
containing metals and PCBs from source area 10(D) and portions of 11(D), the
subsequent offsite disposal of these soils, and the backfill of the source areas
with clean material. A time critical removal action was implemented to remove
these materials from drainage areas ahead of the upcoming rainy season. The
removal action included source removal from upstream drainage areas that were
a part of OU-6 in order to prevent contamination of downstream background
material. The designation AE-C-1 in the OU-6 FS reflects the outcome that the
removal action achieved cleanup goals and post-excavation assessment indicates
no further action is required.
The Buffalo Creek vegetation and sediment removal maintenance actions were
conducted to maintain the discharge from the ARGET groundwater treatment
facility as required under permit from the RWQCB. This action is described in
the Administrative Record for OU-6, including a May 3,2011 completion report.
A sitewide Ecological Risk Assessment is planned as part of the sitewide ROD
(OU 1) following completion of all other RODs for Aerojet. Remedial actions
conducted under the OU-6 ROD (and other RODs) will be assessed from
protectiveness of human health and the environment in the Five Year Review
process.
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Responses to Comments from the Community Advisory Group
Comment #
Comment
Response
6.
Should the benchmark used for lead exposure concentrations be 1 ng/dL,
instead of 10 jig/dL?
OU6 Feasibility Study. Table 1-2. Descriptions of Graphical Risk Summary Figures.
The blood lead level for protection of school children and fetuses (OEUHA, 2007)
for source-specific incremental change should be 1 |ig/dL, not 10 |ig/dL, as the table
and other parts of the report and figures have incorrectly shown. Using 10 jug/dL
would underestimate the benchmark for lead blood concentration, and would not be
protective for school children and fetuses under California regulatory standard.
Therefore, the change in blood lead that is health protective must be re-evaluated and
therefore, additional areas of remediation are likely.
The CAG recommends correcting this source-specific incremental change to 1
(ig/dL, lead on Proposed Plan Page 13 (See Comment 1 Id).
The corrected Table 2a from the Proposed Plan issued in June, 2013 (subsequent
to the public meeting) includes lead cleanup levels based on the DTSC model of
80 mg/kg for unrestricted reuse and 320 mg/kg for industrial or commercial use.
7.
For regions proposed for no action, the CAG recommends the Proposed Plan
address the potential risk of exposure to contaminants in soil, including deeper
soils, if such soils were excavated and reused.
A. Hie CAG raised concerns at a previous CAG meeting over discussions of the
potential unrestricted reuse of soil from no action areas. The CAG is concerned
that soils, including deep soils in regions proposed for no action that are
impacted with contaminants at the present time (or by future migration of
contaminants) could be excavated and used as "clean fill" in an unrestricted
manner both on and off the Aerojet site. See Comment 8 below.
The Selected Remedy includes ICs to prevent unrestricted reuse of soils
containing COCs that could present risk under future exposure scenarios. These
ICs include the requirement to follow Aerojet's Soil Excavation or Grading, or
Construction Debris Movement Notification Requirements which are already in
place sitewide.
In areas where an action is taken to meet remedial action objectives via
excavation, soils with contamination at depths greater than the maximum
excavation depth that could present a risk to unrestricted reuse will be managed
through Aerojet's Soil Excavation or Grading, or Construction Debris Movement
Notification Requirements and ICs.
In all areas of OU-6 where COCs remain at levels that present an unacceptable
risk to potential unrestricted use for soils deeper than 10 feet, the Selected
Remedy will include ICs. Aerojet's Soil Excavation or Grading, or Construction
Debris Movement Notification Requirements will be followed to ensure these
soils are tracked as part of the ICs.
Soils in areas not identified for Remedial Action in the OU-6 ROD were
determined to not present an unacceptable risk to future users of the property.
Protectiveness of the OU-6 remedy will be assessed in Five Year Reviews.
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Responses to Comments from the Community Advisory Group
Comment #
Comment
Response
B. Hie CAG is also concerned that deeper soils may contain elevated levels of
contaminants including TCE, perchlorate, NDMA and 1,4-dioxane. The CAG
recommends that Comment 8 be followed. If Comment 8 is not followed, the
CAG recommends that most contaminants in soil be evaluated according to
residential soil RSLs, including 0.91 mg/kg TCE, 0.0023 mg/kg NDMA, and
4.9 mg/kg 1,4-dioxane. However, the CAG recommends a soil screening level
of 50 mg/kg perchlorate for the protection of the consumption of home grown
produce.
As described in the response to the prior comment, those remaining soils with
COCs exceeding levels appropriate for unrestricted reuse, the selected remedy
will include ICs.
Aerojet's Soil Excavation or Grading, or Construction Debris Movement
Notification Requirements will incorporate the cleanup levels identified in the
ROD on Table 2-2 for soils.
Note the response to the perchlorate level in comment 10 below.
8.
The CAG recommends AJ follow the recommendation of the DTSC import fill
guidance, which states: "Selecting fill Material: In general, the fill source area
should be located in nonindustrial areas, and not from sites undergoing an
environmental cleanup.... Undesirable sources of fill material include industrial
and/or commercial sites where hazardous materials were used, handled or stored as
part of the business operations, or unpaved parking areas where petroleum
hydrocarbons could have leaked into the soil.... Undesirable industrial facilities
including metal processing shops, manufacturing facilities, aerospace facilities, oil
refineries, waste treatment plants, etc." (DTSC, 2001; Information Advisory Clean
Imported Fill Material. (Available at
http://www.dtsc.ca.gov/Schools/upload/SMP_FS_Cleanfill-Schools.pdf). The Clean
Imported Fill Advisory also contains sampling recommendations. The CAG
recommends the recommendations of the DTSC Clean Imported fill Advisory
be considered to ensure that materials used as fill do not pose a risk to human
health both on AJ properties and if considered for reuse off the AJ site.
EPA notes the CAG's recommendation; however, EPA does not impose controls
on those soils that do not pose an unacceptable risk for unrestricted use. As such,
the DTSC advisory is not included as an ARAR in the OU-6 ROD. It is assumed
that any imported fill material brought to the site has previously been determined
to be from a documented clean source (virgin material) that is free from
contamination.
9.
More information should be provided in the Proposed Plan on ICs and
Capping, including vapor barrier depressurizations systems. The EPA has
previously described plans to use a vapor barrier membrane to mitigate vapor
intrusion (VI) to indoor air. The CAG pointed out at a CAG meeting that DTSC does
not agree that a vapor barrier is sufficient, and recommends that a subslab vapor
depressurization system be installed to ensure that VI in to indoor air can be
addressed. Yet these are not even mentioned in the Proposed Plan as part of a
remedy. The Proposed Plan needs to discuss Institutional Controls and Capping and
if and how the vapor barrier and subslab vapor depressurization systems will serve in
these designs.
The ROD documents EPA's selected remedy, which includes the use of
engineering controls to mitigate potential vapor intrusion. Consistent with EPA's
practice, specific details of these systems will be set forth in the remedial design.
Additional details regarding the vapor control systems required as part of the
selected remedy are found in the ROD Sections 2.10.2 and 2.10.3.
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Comment #
Comment
Response
10.
The CAG requests that the US EPA consider using the corrected value of 50
Hg/kg rather than 60 ng/kg as a perchlorate cleanup value in areas that are
planned for residential or mixed use.
Table 2a. Exposure of Perchlorate via home-grown produce. Perchlorate is known to
have high propensity to bioaccumulate in vegetation. In response to CAG's concern
regarding perchlorate exposure via home-grown produce, US EPA responded to
CAG's in its December 2012 letter (US EPA, 2012). In the letter, the US EPA
quantitatively modeled residential exposure of perchlorate and the soil-concentration
above which would be a concern. In that letter, the US EPA determined that a soil-
screening level of 60 jug/kg (ppb) perchlorate in soil would be protective of a child,
assuming 40% of his total vegetation consumption would come from a home-garden.
Thank you for the reevaluation, however, the previous EPA response is correct
and no mathematical error was made. In EPA's calculation, we cited the 2011
Exposure Factors Handbook, http://www.epa.gov/ncea/efli/report.html, for the
consumption of lettuce and leafy vegetables. The values used are derived from
Table 9-6, Consumer-Only Intake of Individual Fruits and Vegetables Based on
the 2003-2006 NHANES (g/kg-day, edible portion, uncooked weight). The
combined body weighted average consumption for both lettuce and leafy
vegetables are 1.5 grams/ kg-day for children 3-5 years and 1.1 grams/kg-day for
females 13-49 years. The comment refers to Table 9-16 which is similar in
methodology but is calculated to present produce as an "agricultural commodity"
which is defined as the produce as it leaves the farm including stems and parts
that may not be consumed. The values are similar but in order to combine the
different female age groups spanning different year brackets, as is the case in
Table 9-17, a time weighting needs to be employed, not a simple addition. Using
this calculation to derive the average per kg-day consumption also yields
1.1 gram/kg-day for the combined age brackets of females 13-19 and 20-49.
Therefore, the previously calculated soil screening levels will be applied.
SSLcliild = 0.060 mg/kg or 60 jug/kg perchlorate SSL woman = 0.090 mg/kg or
90 jug/kg perchlorate. See the Administrative Record for further information.
A. We appreciate the work that US EPA and other regulatory agencies have put in
to respond to CAG's concern. As part of CAG's Technical Assistance Grant, the
human health risk assessor from Skeo's Solution identified a calculation error; if
the error were corrected, the soil-screening level would be lowered from 60
jug/kg to 50 jug/kg for the protection of 13-49 year old women. The CAG agrees
with the Skeo solutions calculations. Hie CAG feels that a 20% difference in
value [(50-60)/50=0.20] is significant. The CAG requests that the US EPA
consider using the corrected value of 50 jug/kg rather than 60 jug/kg as a
perchlorate cleanup value in areas that are planned for residential or mixed use.
Please see the response to Comment 10 above.
B. The CAG also notes that if a greater proportion of vegetables were home
produced, the screening level for protection of 13-49 year old women for
perchlorate would be even lower, with soil screening levels of 40 jug/kg
perchlorate if 50% of the vegetables consumed were home grown, and with soil
screening levels of 25 jug/kg perchlorate if 80% of the vegetables consumed
were home grown. For these reasons, the CAG considers that that a screening
level of no greater than 50 jug/kg perchlorate should be used for the protection of
women and children in the home gardening pathway.
Please see the response to Comment 10 above.
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Comment #
Comment
Response
C. Hie CAG recommends that 50 jug/kg for perchlorate should be added under
"Residential Cleanup Level for the Protection of Human Health" column. The
cleanup value of 60 jug/kg should be continued to be used in areas that are not
designated as residential for the protection of groundwater. However, in areas
that are designated as residential, the CAG strongly recommends the US EPA
use 50 jug/kg as the soil cleanup level (for the protection of women and children
eating home-grown vegetables not exceeding 40% of its diet).
Please see the response to Comment 10 above.
11.
The CAG recommends that EPA follow the correct Regional Screening Levels
(RSLs) or California Modified PRGs for these Chemicals of Concern (COCs)
and modify remedial alternatives accordingly as needed:
A. TPH-diesel and TPH-motor oil: Cleanup levels for TPH-diesel and TPH-motor
oil in the Proposed Plan were above the California RWQCB screening levels for
protection of ground water. The CAG agrees with using California RWQCB
screening levels of 100 mg/kg TPH-diesel and 500 mg/kg TPH-motor oil.
However, if these levels are exceeded, the CAG also recommends also screening
for components including naphthalene, BTEX, and PAHs using residential RSLs.
The revised version of Table 2a issued in June uses the noted California
RWQCB screening levels as proposed cleanup values. The RI and Human
Health Risk Assessment for OU-6 considered the petroleum constituents stated
in this comment, and identified them as COCs if required.
B. Trichloroethylene (TCE): The CAG recommends that Proposed Plan provide
the Residential Soil Regional Screening Level (RSL) of 0.91 mg/kg TCE and the
risk based soil cleanup level of 1.6E-04 mg/kg TCE for the protection of
groundwater as cleanup levels in Table 2a. Since A.T did provide a SERA ESL of
42 mg/kg TCE, it also needs to provide the much lower current soil screening
levels for the protection of direct exposure to soil and for the protection of
groundwater.
Cleanup levels for volatile organic compounds (VOCs) were presented in the
proposed plan and are adopted as performance standards in the ROD based on
target ambient air levels. This is consistent with the approach used for the prior
operable unit at the Aerojet Site (OU-5, the Perimeter Groundwater OU).
C. Cadmium: The CAG recommends Table 5a report the California Modified non-
cancer screening level of 4.0 mg/kg cadmium for residential use and 5.1 mg/kg
for commercial/industrial use (See Human Health Risk Note 3, DTSC ,2013) and
the RSL for the protection of groundwater of 0.52 mg/kg cadmium rather than
the 7 mg/kg listed in the table.
No risk to human health or environmental receptors was identified for cadmium
in OU-6. The protection of groundwater screening level was corrected in the
revised PP issued in June, 2014.
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Comment #
Comment
Response
D. Lead: The CAG recommends the cleanup be protective of a 1 (ig/dL increase in
blood lead in children and in fetuses of pregnant women (See Human Health
Risk Note 3, DTSC, 2013). The CAG does not agree with the lead exposures
that result in 10 jug/dL as stated on Proposed Plan page 13 since it is not health
protective. The CAG does support the cleanup level of 42mg/kg lead for the
protection of groundwater (which is more stringent than residential, and some
cases 23 mg/kg depending on the soil type) for the entire area of OU6 where lead
exceeds this value (see Table 2a, published in June 2013 as an addendum to the
May 2013 Boundary OU Proposed Plan).
The selected remedy in the OU-6 ROD includes soil lead cleanup levels of
80 mg/kg and 320 mg/kg for unrestricted and industrial/commercial use,
respectively. These levels are protective of a l-(ig/dL increase in blood lead
level.
E. Naphthalene, nitrosodimethylamine (NDMA), perchlorate, hexavalent
chromium and polycyclic aromatic hydrocarbons: The CAG recommends
that current RSLs for residential use be listed, and used as Cleanup screening
levels for soil in Table 2a as an additional measure in preventing OU6 soil being
moved onsite or offsite. Using NDMA as an example, the CAG recognizes that
the screening levels protective of groundwater for this compound is very low
(1x10-7 mg/kg); and thus, it is likely not detectable with standard analytical
instrumentation. We do support the EPA's proposed use of 3x10-5 mg/kg for
protection of groundwater instead. The CAG would like to see some mechanism
to prevent movement of soil onsite or offsite, which may ultimately be sold for
residential or gardening purposes. Thus, the CAG would greatly appreciate more
levels of safeguard by adding in soil residential RSLs for NDMA and other
chemicals as an additional measure to prevent inappropriate use or allow
unrestricted use of soil.
Naphthalene, NDMA, and perchlorate were only identified as risks to
groundwater in OU-6; therefore, only cleanup levels for the protection of
groundwater were provided.
Hexavalent chromium and various PAHs pose risks to human health and
groundwater and therefore, unrestricted use, industrial use, and protection of
groundwater cleanup levels for soil were provided.
See response to Comment 8 regarding movement of soils within or off the Site.
12.
The CAG recommends that dredge mine tailings be evaluated for human health
and ecological risks. The Proposed Plan and the RI for the Boundary OU suggested
that dredge tailings from past mining operations occurred. It is unclear if the
Superfimd site includes protection to ecological and human health from past mining
operations. However, Aerojet, by acquiring the property, has inherited the liability of
any potential contaminant hazard from past mining operations. The CAG strongly
recommends that the US EPA, DTSC, and the Water Board evaluate contaminants
from past mining operations and whether the proposed remedy are protective of
future and current land use and wildlife in the open space areas of the Boundary OU.
The entirety of OU-6 - including areas mined in the past - has been assessed for
human health and ecological risk through the risk assessment process described
in the Human Health and Ecological Risk Assessments for OU-6. Under
oversight from EPA, DTSC, and RWQCB, the risk assessments were conducted
in accordance with agency guidance and policy. Identified risks were evaluated
in the FS and remedial actions are selected in this ROD. The selected actions are
protective of human health and the environment. Protectiveness will be
periodically reviewed as part of the Five Year Review process.
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Appendix E-l. Public Meeting Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from the Community Advisory Group
Comment #
Comment
The CAG recommends that EPA improve the Proposed Plan document for
future OUs by addressing the process comments outlined in the attached table.
The CAG does not believe that the OU6 Proposed Plan provides a sufficient level of
explanation for the public to provide informed comments, without a tremendous
amount of investment in understanding the RI/FS. For future Proposed Plans, the
CAG recommends providing the level of detail recommended in the US EPA Guide
to Preparing Superfund Proposed Plans, Records of Decision (RODs), and Other
Remedy Selection Decision Documents (the Guidance), dated July 1999. Because
the Proposed Plan is an invitation for community involvement, we urge the US EPA
to provide enough understandable information to allow for meaningful public
comment as a stand-alone document. Please refer to the attached table for more
detailed recommendations.
Response
EPA is committed to continually improving the RI, FS, and PP process and
community engagement throughout the process. EPA incorporated feedback
from the community on the OU-3 and OU-5 Proposed Plans in preparation of the
OU-6 Proposed Plan. We appreciate the feedback on this proposed plan and will
work with the CAG to incorporate this feedback into future proposed plans for
other OUs at the Aerojet Site.
Hie Proposed Plan for OU-6 is a summary of EPA's preferred alternative for the
entire operable unit, and struck a balance between including as much information
as possible while maintaining a useful and readable "summary" format for the
public. Information from the entirety of the Administrative Record for OU-6
was incorporated by reference, but EPA understands the community requests
additional information in future proposed plans. EPA will continue working with
the CAG to ensure meaningful community input that leads to unproved proposed
plans hi the future.
Appendix E: Public Participation and Issues Related to the Presentation of the Proposed Plan
Recommendation
Supporting Comment
Response
A. The CAG recommends using the NCP
criteria for future Proposed Plans.
NCP Section 300.430(e)(9)(iii) requires that "The criteria noted hi
paragraph (e)(9)(iii) of this section are used to select a remedy."
The Feasibility Study and the Proposed Plan do not compare the site
against the NCP criteria but use the Management Area; The CAG
feels that this is the incorrect use of comparison because the decision
for selecting one alternative over the other is based on Remedial
Action Area.
EPA appreciates the CAG's input to make future proposed
plans clearer and more useful to the public and will consider
this input for future proposed plans. The proposed plan
summarizes the analysis of the remedial alternatives against
NCP criteria that was conducted hi the administrative record
(including the Feasibility Study).
B. The CAG recommends using the
regulatory guidance for writing of future
Proposed Plans.
While the Guidance is not legally binding, certain elements are
required by law to be hi the Proposed Plan (such as a list of preferred
alternatives and reasons for them).
EPA appreciates the CAG's input to make future proposed
plans clearer and more useful to the public and will consider
this input for future proposed plans.
C. The CAG recommends EPA scale down
their scope of remedial action into
smaller Proposed Plans.
EPA appreciates this comment and understands the site is
complex. The division of the Aerojet site into 9 OUs was
directed hi the Partial Consent Decree and EPA will propose
remedies on this basis.
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Appendix E-l. Public Meeting Comments
Appendix E: Public Participation and Issues Related to the Presentation of the Proposed Plan
Recommendation
Supporting Comment
Response
D. The CAG recommends EPA include the
cost for each remedial action area in
future Proposed Plans.
The Guidance states "a total present worth cost for each alternative
allows the public to compare different alternatives that have varying
amount of O&M costs." Hie grouping of costs by Management Area
is also not helpful in making such comparison.
EPA will work with the CAG to present information more
clearly in the future.
E. The CAG recommends EPA follow its
own guidance for newspaper
notifications, found in Section 2.6.1 of the
Guidance [US EPA 1999],
Comment noted.
F. The CAG recommends that future
Proposed Plans describe the nature and
extent of contamination in greater depth.
More information on the levels of each contaminant of concern and
its extent would be helpful for public understanding and comment.
EPA will work with the CAG to discuss the nature and extent
of contaminants of concern through the RI/FS process.
G. The CAG recommends that EPA update
the risk assessment in the RI/FS with up
to date human health toxicity criteria.
The CAG understood that EPA, if not planning to update this
information in the RI/FS, would include up to date human health
toxicity criteria in the OU6 Proposed Plan. The CAG would also like
to see more information on the following in future Aerojet OU
Proposed Plans:
Maximum level of contaminants or the 95%UCL exposure point
concentration of contaminants on the site or in each exposure
unit.
Clean up levels for all contaminants in soil.
Correct contaminant screening levels (more health protective of
RSLs and OEHHA/Cahfornia-modiiied screening levels) for all
contaminants of potential concern.
Detailed human health risk calculations.
EPA's intent was to provide proposed cleanup levels in the
Proposed Plan that were consistent with current regulatory
guidance and human health toxicity criteria. These cleanup
levels were reviewed following the proposed plan, and the
cleanup levels provided in the ROD are selected based on
current human health and ecological toxicity information
EPA will work with the CAG to include useful information in
future proposed plans that is responsive to this request. We note
that the OU-6 PP included cleanup levels for all COCs, as
requested by the CAG in discussions prior to issuance of
tlie PP.
The cleanup goals and performance standards selected in the
OU-6 ROD reflect current risk screening levels appropriate for
tlie site.
It will likely be infeasible to present all risk assessment
calculations in future PPs for tlie site given tlie complexity and
scope of tlie OUs. Tlie human health risk assessment is
available as part of tlie Administrative Record for OU-6 and
will be made available as part of tlie Administrative Records
for future OUs.
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Appendix E-l. Public Meeting Comments
Appendix E: Public Participation and Issues Related to the Presentation of the Proposed Plan
Recommendation
Supporting Comment
Response
H. The CAG recommends future Proposed
Plans go into greater detail in the
Summary of Site Risks.
The CAG recommends the following details be included in future
Proposed Plans:
Hie estimated carcinogenic and non-carcinogenic risks associated
with exposure pathways for chemicals of concern (COC).
Summary of risk assessment for each remedial action area.
Human health risks that explain if human health risks levels
exceed a cancer risk of 1 x 10-6 or Hazard Index of 1 for an
industrial scenario or residential scenario or both.
EPA will work with the CAG to include as much of the
requested information as possible into future proposed plans,
while maintaining brevity that allows for the PP to be widely
distributed and used by the public. All information will be
included in the Administrative Record for this and future OUs.
I The Proposed Plan should include a
summary of site risks, other than a
description of how risks were determined.
There is no summary of site risks (human health or ecological health)
other than a description of how risks are determined. The Proposed
Plan discusses, to a very limited extent, US EPA's preferred
alternatives. However, without a description of site risk (exceeding
industrial, exceeding residential, and/or exceeding ecological health),
the reader is left to speculate on the magnitude and level of risk for
each Remedial Action Area. As noted above, the US EPA neglected
to discuss Remedial Action Areas for which No Action is selected.
In other words, US EPA does not provide a link on the level of
risk/hazard (not significant - cancer risk 1 x 10-6 and Hazard Index
of 1.0 or significant - cancer risk 1 x 10-6 to 1 x 10-4 or Hazard
Index >1.0) and type of use (industrial, commercial, residential,
or ecological) from contaminants for each Remedial Action Area.
The CAG emphasizes Remedial Action Areas because the
Preferred Alternatives are made by Remedial Action Areas, not
Management Areas.
Table 1 in the proposed plan was intended to summarize the
types of COCs that present risks under planned future use
scenarios for each of the Remedial Action Areas. Detailed risk
summary information was derived in the human health risk
assessment and summarized in the FS, which are incorporated
by reference into the PP as part of the Administrative Record.
EPA recognizes that the CAG requests more detailed
information to be include as part of future PPs.
J. Previous cleanup action conducted at
Buffalo Creek should have been disclosed
as a part of the Proposed Plan.
Previous cleanup action conducted at Buffalo Creek is not disclosed.
As described by the Regional Water Quality Control Board project
manager via telephone on May 17,2013, there was a previous
cleanup action immediate downstream from the Proposed remedial
action for Buffalo Creek. The subject document does not describe
this nor does it propose ways to evaluate likely re-contamination
from upstream Buffalo Creek, where contamination levels are so
high that US EPA proposes a remedial action.
The cleanup alternative selected for Buffalo Creek will meet
the required cleanup goals and is expected to remove COCs
that could migrate downstream in Buffalo Creek.
The effectiveness of the cleanup will be documented in a
post-construction report, and any future monitoring of Buffalo
Creek will be described in the RD. A prior maintenance action
conducted by Aerojet under its NPDES permit for treated
groundwater is in the May 3,2011 completion report included
in the Administrative Record for OU-6.
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Appendix E-l. Public Meeting Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from the Community Advisory Group
Comment #
Comment
Response
Written Comments submitted by Mr. Allen Tsao, a member of the CAG, on the Proposed Plan for the OU-6 Cleanup
(Comments dated September 20,2013)
General Comments
1.
Please specify the total acreage of OU6 property. I was not able to find this
information in the RI/FS or the Proposed Plan.
The total acreage for OU-6 is 701 acres and is included in the ROD.
2.
Institutional Controls as a stand-alone remedy
A. According to an US EPA's policy (http://www.epa.gov/superfimd/policy/ic/), it
indicates that the National Contingency Plan (NCP) emphasizes that ICs are meant to
supplement engineering controls (Alternative 3 for OU6 Proposed Plan) and that ICs
will rarely be the sole remedy at a site. However, US EPA indicated for a number of
sites under OU6, the preferred remedy is IC alone as the sole remedy. It is my
understanding that once an IC is selected, the enforcement goes to the state (and
perhaps local municipalities). Is there a reimbursement mechanism for passing the
burden to the State to enforce and monitor IC compliance?
ECs are the preferred remedy for the areas of OU-6 for risk due to vapor
intrusion and the groundwater ICs are applicable to all Aerojet properties that
overlie groundwater contamination (as described in the OU-5 ROD). Restrictions
on the installation of wells and use of groundwater are the only feasible methods
to prevent exposure to contaminated groundwater or interference with the
groundwater remedies from other OUs at the site. ICs will be enforced by the
land owner and PRP entering into an enforceable Land Use Covenant with
DTSC. As a third-party beneficiary, EPA will also have the ability to enforce this
agreement. The California Code of Regulations (CCR) provides a mechanism for
cost recovery by the State for ICs.
B. How does US EPA ensure that ICs do not fail, especially when property are sold
for private housing development.
EPA will continue to review the remedy for all areas of the Aerojet site at a
minimum of once every five years as part of the five year review process. In
addition, the LUC between the PRP and DTSC will require annual reporting to
ensure appropriate ICs and engineering controls are in place.
C. As Table 3 in the Proposed Plan indicates, ICs may not be compliance with
ARARs and not protective of the overall protection of human health and the
environment for areas identified with risk to groundwater (or with PCB
contamination).
The selected ICs for OU-6 comply with ARARs for the selected remedy. The
referenced Table in the Proposed Plan was intended as a summary of the relative
ability of each potential remedial alternative to meet NCP criteria. In the analysis
of the lead and support agencies, the selected alternative will meet threshold NCP
criteria.
D. It also states that ICs alone would only partially achieve long-term effectiveness
and permanence. Therefore, I am not convinced that ICs is a compelling choice for
residential, mixed used, or commercial land-use.
The referenced Table in the Proposed Plan was intended as a summary of the
relative ability of each potential remedial alternative to meet NCP criteria. Where
selected in the OU-6 ROD, ICs (and, where necessary, in conjunction with
engineering controls such as vapor barriers and other mitigation measures), will
be effective over the long term. The protectiveness of these measures will be
periodically reviewed by EPA to ensure they remain protective.
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Appendix E-l. Public Meeting Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from the Community Advisory Group
Comment #
Comment
Response
Specific Comments
1.
AW-SV-R-1 and L2-SV-R-1: These two sites are designated as mixed use. Please
explain why the US EPA preferred alternative, Alternative 2 - ICs - would alone be
protective or consider to revise this to another active remedy that has long term
permanence. Risks at AW-SV-R-1 and L2-SV-R-1 are from VOC migration from
groundwater to indoor air. As Table 3 in the PP indicates, ICs alone is not protective
of the overall protection of human health and the environment for areas identified
with risk to groundwater.
EPA appreciates the opportunity to clarify the selected remedy for these areas.
Hie selected remedy for AW-SV-R-1 and L2-SV-R-1 has been changed to
Alternative 3 (ECs). ECs have been selected for these remedial areas to prevent
potential migration of VOCs from contaminated groundwater to indoor air.
2.
L5-SV-R-3: This site is designated as residential. Please explain why Alternative 2 -
ICs - would alone be protective or consider to revise this to another active remedy
that has long term permanence. Risks at this residential area, L5-SV-R3, is from
VOC migration from groundwater to indoor air. As Table 3 in the PP indicates, ICs
alone is not protective of the overall protection of human health and the environment
for areas identified with risk to groundwater.
The EPA appreciates the opportunity to clarify the selected remedy for this area.
The selected remedy for L5-SV-R-3 has been changed to Alternative 3 - ECs.
ECs have been selected for these remedial areas to prevent potential migration of
VOCs from contaminated groundwater to indoor air.
26 OF 26
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Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWQCB, Engineering & Water Resources, and Aerojet Rocketdyne
ฆฆฆฆฆJ
( iimnu-nkT: Mr. SU-m- Khss, D I SC. I'miiim-iils d;ik-d .Iiiik- 10, 2013
1.
Thank you for providing an opportunity to provide input to a draft version of the
Plan. The Department of Toxic Substances Control (DTSC) concurs with the Unites
States Environmental Protection Agency (EPA's) effort to proceed towards a remedy
decision for the Boundary Operable Unit (BOU). The comments provided here are
aimed towards those elements of the Plan that were revised and not made available
for DTSC review and to provide information regarding State Applicable Relevant
and/or Appropriate Standards (ARARs) under DTSC purview which were missing in
BOU feasibility study, Appendix A. Also, elements of DTSC guidance documents
may serve as To Be Considered (TBC) standards that prove useful as performance
standards for EPA's development of the Record of Decision (ROD).
Comment noted.
2.
State ARAR: Institutional Controls (ICs) include the use of land use covenants
(LUCs) as described in 22 CCR 67391.1(a)(b)(d)(g)(i) CA Civil Code Section
1471 (a). CCR Title 22, section 67391.1 is an environmental covenant type
regulation. The ROD needs to contain sufficient detail regarding the use of ICs.
DTSC is unable to concur in a response action decision document (e.g. ROD) which
includes limitations on land use or other ICs unless the limitations or controls are
clearly set forth and defined in the decision document. The ROD should specify the
limitations or controls that are to be incorporated into an appropriate LUC for the
protection human health and the environment. LUCs are recorded in the county
recorder's office and run with the land. This will allow the Agencies to ensure the
long-term protectiveness of the land and help to establish a) the prohibited sensitive
uses and b) the prohibited activities on the property subject to restrictions.
ARARs for OU-6 are included in the OU-6 ROD (Table 2-13).
3.
The Assessor Parcel Numbers (APNs) in the BOU are undefined in the feasibility
study. If the information is provided in the ROD, it will assist the Agencies in
defining which written legal descriptions may be useful and which will require
surveys to define Remedial Action Area (RAA) boundaries subject to land use
restrictions. From review of Sacramento County Assessor parcel viewer,
APNs 072-0231-129-0000, 072-0231-128-0000, 072-0231-079-0000, 072-0231-125-
0000, 072-0231-102-0000, 072-0231-081-0000, 072-0231-126-0000, 072-0231-116-
0000, and 072-0231-134-0000 appear to overlay in whole or in part the RAAs in the
BOU.
The APNs, as provided in the comment, are included in the OU-6 ROD,
Section 2.6.
Aerojet provided the following APNs for OU-6 as follows:
072-0231-116
072-0231-119
072-0231-120
072-0231-128
072-0231-129
072-0231-134
The total acreage of OU-6 is 701 acres.
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment #
Comment
Response
4.
Hie lateral extent of the properties subject to land-use restrictions would be
confirmed by a survey with written legal description. For vapor intrusion (VI)
mitigation requirements, LUCs may include ICs with prescribed notifications,
prohibitions, restrictions and requirements that must be utilized to ensure O&M and
disclosure of the risks, restrictions, and requirements to future buyers and occupants.
Provisions in the LUC may include 1) notice of the existing conditions known to
the environmental agency that may cause potential unacceptable risk from VI;
2) prohibition against specific uses of the property; 3) prohibition against interference
with the VI mitigation system; 4) prohibition against activities that will disturb
impacted soil without DTSC approval; 5) right of access to the property for Agencies
to inspect, monitor, and perform other activities relative to the VI mitigation system;
6) right of access to the property for the person responsible for implementing the
O&M activities relative to the VI mitigation system; and 7) inspection and reporting
requirements for the owner of the property.
Comment noted. Details regarding the LUCs, ICs, and ECs are included in the
OU-6 ROD in Sections 2.10.2 and 2.10.3. Additional details will be set forth in
the Remedial Design.
5.
TBC: Any contaminated soils brought to the surface by grading, excavation,
trenching or backfilling from property subject to a County recorded LUC restriction
shall not be conducted without a plan approved by the appropriate lead agency. EPA
should consider outlining the performance standards of this plan and activities which
trigger its development. Possible elements to consider are 1) introduction, site
background, purpose of plan, notification requirements, etc.; 2) identification of
activities subject to this plan (e.g. soil excavation, soil removal, etc.); 3) description
of soil excavation and management procedures; 4) procedures of sampling and
analysis where excavated soil is to be relocated onsite or shipped offsite; and 5)
preparation of a report and submittal within x days of the completion of the work to
include description of excavation activities, deviations from plans, sample results,
disposition of soil, photos, figures, field notes, copies signed manifests, copies of
chain of custody forms, and copies of weight tickets, if applicable.
ARARs for OU-6 are included in the OU-6 ROD, Table 2-13.
6.
TBC: DTSC has issued the Vapor Intrusion Mitigation Advisory (VIMA or
Advisory) for use on sites that may be impacted by soil vapor intrusion into indoor
air. The mitigation alternative described in the Advisory are response actions
designed to interrupt or monitor the vapor intrusion pathway and to ensure public
safety until the source of volatile chemical concentrations causing the vapor intrusion
risk has been restored to concentrations at or below levels considered safe for human
exposure. The Advisory describes mitigation technologies such as subslab
depressurization (SSD) or subslab venting (SSV) systems. EPA may want to
consider elements from this Advisory as performance standards in the ROD.
ARARs for OU-6 are included in the OU-6 ROD, Table 2-13.
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment #
Comment
Response
7.
TBC: Hie Advisory identifies VI mitigation as a preemptive solution for a perceived
rather than actual threat for a site where no building yet exists and fate and transport
modeling indicates an acceptable risk (determined to be at or less than a 1 x 10-6 risk
level or a hazard index (HI) of 1) to future building occupants. In such instances and
as a prudent measure, a developer may choose to install VI mitigation measures
despite the apparent low risk. However, for such preemptive applications, DTSC will
neither approve nor enforce the preemptive mitigation application and will not be
involved in the O&M for the VI mitigation system.
ARARs for OU-6 are included hi the OU-6 ROD, Table 2-13.
8.
The proposal for RAA AE-R-1 through AE-R-6 is Containment/Operational
Controls through Capping (Alternative 3) with planned commercial use. For
Alternative 3 (Capping), engineering controls (ECs) and ICs will be necessary to
prohibit unauthorized activities that would disturb the integrity of the cap remedial
system and prohibit unauthorized activities that would bring contaminants to the
surface.
Engineering controls and institutional controls are included as a component of
the selected remedy [Alternative 3, incorporating Alternative 2 ICs (Capping)]. The
ECs and ICs will prohibit unauthorized activities that would disturb the integrity
of the cap remedial system and prohibit unauthorized activities that would bring
contaminants to the surface.
9.
The proposal for RAA AW-R-14 is Containment/Operational Controls through
Capping (Alternative 3) with a planned mixed use setting. As mixed use may include
sensitive uses (e.g. residents), the ECs and ICs must be protective of the remedial
system and sensitive groups.
The selected remedy for AW-R-14 has been changed from Alternative 3,
Capping (as described hi the OU-6 PP) to Alternative 4 (Source
Removal/Reduction - Excavation) and is documented hi Appendix B of the
OU-6 ROD.
10.
Dredge Pit and Eastern Basin is planned for industrial use. For RAA DPEB-R-1,
Containment/Operational Controls through Backfilling is proposed (Alternative 3).
ICs on future land uses would be necessary for cleanup completed to these levels.
The institutional control component of the selected remedy [Alternative 3,
incorporating Alternative 2 ICs (Backfilling)] will address future land uses for this
site.
11.
The proposal for RAA AE-R-7 through AE-R-9 is Source Removal/Reduction
through Excavation (Alternative 4) in a planned commercial use setting. The
proposal for RAA CP2-R-1 through CP2-R-11 is Source Removal/Reduction
through Excavation (Alternative 4) in a planned industrial use setting. For
Alternative 4 where residual contamination is left in place that does not allow for
unrestricted use, ICs would become necessary on future land uses for cleanup to
these levels.
Institutional controls that restrict land uses hi areas where contamination remains
hi place are a component of the selected remedy.
12.
The proposal for RAA AW-R-1 through AW-R-13, AW-R-15, and L2-R-1 through
L2-R-8 is Source Removal/Reduction through Excavation (Alternative 4) hi a
planned mixed use setting. As mixed use may include sensitive uses (e.g. residents),
the ICs must be protective of these sensitive groups.
Institutional controls that restrict land uses hi areas where contamination remains
hi place are a component of the selected remedy (Alternative 4).
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ippendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWQCB, Engineering & Water Resources, and Aerojet Rocketdyne
13.
The proposal for RAA L2-SV-R-2 and L2-SV-R-3 is Source Removal/Reduction
through S VE (Alternative 4) in a planned mixed use setting. For Alternative 4 (SVE)
where residual contamination is left in place that does not allow for unrestricted use,
ECs and ICs will be necessary 1) to prohibit unauthorized development and 2)
prohibit unauthorized activities that would disturb the integrity of the SVE
remediation and monitoring system and 3) prohibit unauthorized activities that would
bring contaminated soil the surface. As mixed use may include sensitive uses
(e.g. residents), the ECs and ICs must be protective of these sensitive groups.
The ECs and ICs component of the Alternative 4 remedy will prohibit
unauthorized development, unauthorized activities that would disturb the
integrity of the SVE remediation and monitoring system, and unauthorized
activities that would bring contaminated soil the surface. In addition, the ECs and
ICs will protective of sensitive groups (e.g., residents).
14.
Line 5 North is planned for residential use. The proposed excavations for L5-R-1
through L5-R-4 would need to meet standards for residential use.
Agreed.
15.
The proposal for RAA AE-SV-R-2, AE-S V-R-4 through AE-S V-R-8, is Source
Removal/Reduction through SVE (Alternative 4) in a planned commercial use
setting. The proposal for RAA CP2-SV-R-1 through CP2-SV-R-5 is Source
Removal/Reduction through SVE (Alternative 4) in a planned industrial use setting.
For Alternative 4 (SVE) where residual contamination is left in place that does not
allow for unrestricted use, ECs and ICs will be necessary.
Agreed. The selected remedy (Alternative 4) includes an EC and IC component.
16.
The proposal for RAA L5-SV-R-1 and L5-SV-R-2 is Source Removal/Reduction
through SVE (Alternative 4) in a planned residential use setting. Where residual
contamination is left in place that does not allow for unrestricted use, ECs and ICs
will be necessary 1) to prohibit unauthorized development and 2) prohibit
unauthorized activities that would disturb the integrity of the SVE remediation and
monitoring system and 3) prohibit unauthorized activities that would bring
contaminated soil to the surface.
The EC and IC component of the Selected Remedy (Alternative 4) will address
the issue of contamination remaining in place.
17.
RAA AE-SV-R-1 is relatively close to AE-SV-R-2 and may be indistinguishable
given the similar VOCs in this area (e.g. vinyl chloride). Source Removal/Reduction
(SVE) similar to AE-SV-R-2 appears warranted for this area.
Agreed. These two areas are now combined and the contamination will be
addressed under AE-SV-R-l/R-2.
18.
The proposal for RAA AE-S V-R-3, AW-SV-R-1, L2-SV-R-1, MA-SV-R-1,
DPEB SV-R-1, and CP2-SV-R-6 is ICs due to modeled VOC migration from
groundwater attributing to possible risk to human health in indoor air in a residential
setting. To ensure the long-term protectiveness, specific limitations or controls would
need to be in place before allowing sensitive uses.
Agreed.
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment #
Comment
Response
19.
RAA L5-SV-R-3 is planned for residential use. ICs are proposed due to modeled
VOC migration from groundwater attributing to possible risk to human health in
indoor air in a residential setting. To ensure the long-term protectiveness, specific
limitations or controls would need to be in place before allowing sensitive uses.
Agreed.
20.
RAA L5-R-2, L5-R-3, L5-R-4, L5-SV-R-1, and L5-SV-R-2 are identified as threats
to groundwater. ICs for residual contaminants which pose a continuing threat to
groundwater would become necessary.
Agreed. After the remedial action, if contamination remains in place that
continues to pose a threat to groundwater, ICs will be required.
21.
Buffalo Creek and West Lakes are planned for open space or drainage. For
excavation where residual contamination is left in place that does not allow
unrestricted use, ICs would become necessary.
Agreed. After tire remedial action, if contamination remains in place that does not
allow for unrestricted use, ICs will be required.
22.
There are no vapor cleanup levels in Table 2b as the clean-up is designed to meet
ambient air levels. There is a footnote about protective soil vapor levels in subsurface
being decreased by location and depth specific attenuation factors. If the purpose is to
reduce the level of contamination in subsurface that is acting as a source of potential
indoor air vapors, response action based goals should be considered or a mechanism
defined to reach these values. It is unclear how the ROD will establish specific soil
vapor values as performance stands in this media for deciding when to rim a soil
vapor extraction system off or to gauge success.
Tire cleanup levels selected in tire ROD are to attain these specified protective
levels in indoor air. Cleanup levels for SVE in soil will be depth- and
site-specific, and tire method for calculating these levels will follow DTSC
guidance in tire remedial design and remedial work plans. This approach is
consistent with tire method currently being implemented in OU-5 at tire Site.
23.
For the RAAs that propose ICs (Alternative 2) only, limitations or controls as
performance standards are not clear. For the ROD, consider performance standards
that 1) describe the mitigation technology most likely to be chosen (subslab
depressurization (SSD) or subslab venting (SSV) systems); 2) provide general
guidance and design detail for installation of SSD and SSV systems and other
mitigation technologies; 3) provide guidance for establishing operation and
maintenance (O&M) requirements for VI mitigation technologies; and 4) provide
guidance for implementation measures.
Tire ROD clarifies that ICs must prevent exposure and/or maintain tire integrity
of remedial systems. Specific technologies will be set forth in tire Remedial
Design for OU-6.
24.
Hie Aerojet RCRA units in the BOU are unclear in the Plan. Consider consolidating
the RCRA units that are closed and those that are operating and those that have been
deferred to CERCLA for the BOU. For instance, the deep underground injection
wells are subject to post closure permit requirements.
There are ten RCRA units located within OU-6. All ten units have been closed
under tire RCRA program, and none of them have been deferred to CERCLA.
25.
For lead, OEHHA has replaced the 10 (rg/dL "level of concern" with a
source-specific "benchmark change" of 1 ng/dL.
Tire OU-6 ROD presents tire updated level of concern for lead of 80 nrg/kg for
unrestricted and 320 nrg/kg for industrial/commercial use.
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment #
Comment
Response
26.
Hie mercury industrial soil RSL is 43 mg/kg instead of 180 mg/kg value provided in
Table 2a of the PP.
The cleanup levels have been updated and corrected and were re-issued as part of
the OU-6 PP Extension notice (dated June 2013). The mercury cleanup level was
further corrected to 40 mg/kg (2015 RSL value).
27.
The trichloroethylene residential soil RSL is 0.91 mg/kg.
TCE in soil within OU-6 does not pose a risk to human health, only ecological
receptors. Therefore, a cleanup level for the protection of human health is not
required.
28.
The trichloroethylene industrial soil RSL is 6.4 mg/kg.
TCE in soil within OU-6 does not pose a risk to human health, only ecological
receptors. Therefore, a cleanup level for the protection of human health is not
required.
29.
Pentachlorophenol human health soil values for residential and industrial are not
included in Table 2a. This COC is present at Chemical Plant 2.
While pentachlorophenol may be present in soils at Chemical Plant 2, the
concentrations identified do not pose a risk to human health, ecological receptors,
or groundwater. Therefore, it was not identified as a COC and does not require a
cleanup level.
30.
1,1,1 -Trichloroethene should be 1,1,1 -Trichloroethane.
The correction was made in the OU-6 ROD.
31.
Naphthalene soil cleanup level for protection of human health is not included in
Table 2a.
The soil cleanup level for naphthalene for the protection of groundwater will be
added to the cleanup level table to be included in the OU-6 ROD (naphthalene in
soil does not pose a risk to human health, only to groundwater). See Table 2-2 hi
the OU-6 ROD.
32.
Freon 113 ambient level is not included in Table 2b.
Cleanup levels for VOCs hi ambient ah were only provided for VOCs that posed
a risk. These VOCs include:
1,1-DCE
1,2-DC A
Benzene
Chloroform
cis-l,2-DCE
PCE
TCE
Toluene
Vhiyl chloride
The cleanup levels for these VOCs are presented on Table 2-3 hi the OU-6 ROD.
33.
1,1-Dichloroethene ambient level in included in Table 2b.
See the response to comment #32.
34.
Trans- 1,2-dichloroethene ambient level is not included in Table 2b.
See the response to comment #32.
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment #
Comment
Response
35.
Hexaiie ambient level is not included in Table 2b.
See the response to comment #32
36.
Carbon tetrachloride is ambient level is not included in Table 2b.
See the response to comment #32
37.
1,3-Butadiene ambient level is not included in Table 2b.
See the response to comment #32
38.
1,2,4-Trimethylbenzene ambient level is not included in Table 2b.
See the response to comment #32
39.
Tetrahydrofuran ambient level is not included in Table 2b.
See the response to comment #32
40.
State ARAR: California Health & Safety Code, Div. 20, Chapter 6.5, Sec 25100
et seq.; Statutes governing hazardous waste control, management and control of
hazardous waste facilities, transportation, laboratories, classification of extremely
hazardous, hazardous and non-hazardous waste; applicable hazardous waste
standards.
ARARs for OU-6 are included in the OU-6 ROD.
41.
State ARAR: California Health & Safety Code, Div. 20, Chapter 6.8, Sec 25300
et seq.; California "Superfimd" Law, Hazardous Substance Account Act/Hazardous
Substances Cleanup Bond Act. Certain portions may be relevant or appropriate or
TBC standards for assessing the completeness of response actions where hazardous
substances remain which does not allow for unrestricted use.
ARARs for OU-6 are included in the OU-6 ROD.
42.
State ARAR: California Code of Regulations (CCR), Title 22, Division 4.5, Chapter
33; Sections 67384.1-67384.11; Perchlorate Best Management Practices; establishes
the best management practices for perchlorate materials as described in section
67384.2.
(see original comments for link to document)
ARARs for OU-6 are included in the OU-6 ROD.
43.
State ARAR: The California legislature passed Assembly Bill 422 (AB 422) in
October 2007, amending Section 25356.1.5 of the California Health and Safety
Code, and adding Section 13304.2 to the Water Code. AB 422 requires that the
exposure assessment of any health or ecological risk assessment prepared in
conjunction with a response action taken or approved pursuant to eh California
Superfimd Act include the development of reasonable maximum estimates of
exposure to volatile chemicals that may enter structures that are on the site, or that
are proposed to be constructed on the site, and may cause exposure due to the
accumulation of volatile chemical in the indoor air of these structures.
ARARs for OU-6 are included in the OU-6 ROD.
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment #
Comment
Response
Commenter: Mr. Steve Nugent, Carmichael Water District, comments dated June 5, 2013
1.
Hie Proposed Plan does not address groundwater cleanup goals for existing
contaminated groundwater in OU6. Table 2 provides cleanup levels for soil and
ambient air, but not for groundwater. Although groundwater cleanup is identified as
part of the larger Aerojet sitewide cleanup; groundwater cleanup and treatment goals
should be restated here, and the goals need to consider the regulatory authority of the
California Department of Public Health with regard to beneficial use and permitting
as a drinking water supply. This includes the consideration of clean up levels to
below the Maximum Contaminant Levels.
The contaminated groundwater beneath the Aerojet Superfund Site, including
groundwater beneath OU-6, is being addressed as part of the ongoing interim
and final remedial actions to provide hydraulic containment and remediation of
the contamination associated with releases from Aerojet. As described in the
proposed plan, groundwater remediation is being conducted on an Aerojet
sitewide basis. These final and interim remedies for the groundwater
are managed under the OU-3 ROD (EPA, 2001) and OU-5 Interim ROD for
Groundwater (EPA, 2011). The final groundwater remedy with aquifer
restoration goals, will be documented in the sitewide ROD (OU-1 ROD). The
OU-3 and OU-5 RODs include more details on the ongoing remedial actions
for groundwater. Evaluations that consider the actual performance of the remedy
and incorporate water level monitoring that considers other uses of groundwater
in the area. EPA will continue these evaluations as required. It is not expected
that remediation of groundwater sources within OU-6 will impact groundwater
levels outside of OU-6.
2.
The Proposed Plan needs to state that groundwater contamination exists at levels
exceeding the regulated Maximum Contaminant Levels for several contaminants of
concern for groundwater below the OU6 areas and there is no foreseeable beneficial
use scenarios for groundwater present within OU6 that involve direct domestic use as
defined in Policy Memo 9-005 Policy Guidance for Direct Domestic Use of
Extremely Impaired Sources.
The Proposed Plan and ROD are intended to show those areas requiring remedial
action within OU-6. However, there are plumes exceeding drinking water
standards that extend beyond OU-6. These are shown on a composite plume map
Figure 2-13 with detailed maps in Appendix A in the ROD.
3.
The Human Health and Ecological Risk Assessment, Volume 2, Boundary QU RI/FS
(Aerojet 2012) considered that if the "...risk of contaminating groundwater was
considered moderate, than the area may have been recommended for cleanup
depending on the compound mobility and solubility, and depth and extent of
contamination." Priority of reduction of groundwater contaminant source areas such
as Chemical Plant 2 Area and the Dredge Pit and Eastern Basin areas needs to be
given a high priority to protect from increasing contaminant levels in the
groundwater moving offsite. The District therefore supports Alternative 4 Source
Removal/Reduction as the preferred alternative.
Comment noted. The Selected Remedy does include Source Reduction/Removal
in the Chemical Plant 2 area. Capping was selected as the remedy for the Dredge
Ponds/Eastern Basin, because the identified risk was to direct contact and not to
groundwater.
Commenter: Mr. Alex MacDonald, CVRWQCB (comments dated May 3, 2013)
1.
Page 2, Column 2, Site Background, first paragraph. Aerojet acquired the Rancho
Cordova site in December 1950. Aerojet received waste discharge requirements in
May 1952.
This correction was made in Section 2.3 of the ROD.
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment #
Comment
Response
2.
Page 3, Table 1, Source Area AE-R-2. The soil vapor contamination beneath this
source area should be removed with SVE. The area requiring remediation extends
along nearly the entire corridor between Buildings 20002 and 20004 and can include
areas beneath those two buildings. This would extend from AE-SV-R-8 to near
AE-SV-R-5 and encompass AE-SV-R-7. One of the problems was that the figures
used to delineate the source areas do a very poor job of showing the extent of
contamination that is being addressed. See comment below on the Figures XXX.
The soil vapor contamination at AE-R-2 will be captured by the SVE remedy
associated with AE-SV-R-7/R-8. The excavation remedy is still needed at AE-R-
2 to address the soil contamination (iron and Aroclor-1254 are the soil COCs
associated with AE-R-2). The extent of the soil vapor contamination will be
defined during the remedial design, and will include the soil vapor contamination
identified at AE-R-2. The 1,1,2,2,-PCA contamination identified as a COC for
AE-R-2 has been added as a COC for AE-SV-R-7 to ensure that this
contamination is also addressed in this area.
3.
Pages 7, 8 and 9. Hie reader should be informed that the delineation of the source
areas likely does not represent the extent of contamination at each location that is part
of the remedy due to the extent needs further delineation in many cases. In addition,
the interpolation program that was used does not do a very good job of interpolation
of the contaminant concentrations.
The ROD text has been clarified to explain that the RAAs presented on the
figures do not represent the actual extents of contamination and that further
delineation in most areas is needed as part of the Remedial Design and the
Remedial Action for OU-6.
4.
Page 10, second column, second sentence. The proposed remedy will not prevent
COCs from migrating to groundwater. What is being done is removing COCs from
the vadose zone to allow return of the groundwater to meet beneficial uses. COCs
will migrate to groundwater but at concentrations that would cause impairment of
beneficial uses.
Comment noted. The selected remedy is to prevent COCs from continuing to
groundwater at concentrations that would impair beneficial uses.
5.
Page 10, second column, third paragraph. Sediments were also evaluated for
potential adverse impacts on human health.
The text in the ROD has been clarified, in Section 2.7, that sediments were also
evaluated for potential adverse impacts on human health.
6.
Page 11, Table 2a. The protection of groundwater value for hexavalent chromium
should be 0.2 mg/L using the DLM and the PHG of 0.02 jug/L, while allowing for a
1000 fold attenuation factor. I do not know how the value presented in the table was
obtained.
The cleanup levels have been updated and corrected and were re-issued as part of
the OU 6 PP Extension notice (dated June 2013). The cleanup level for
hexavalent chromium for the protection of groundwater has been corrected to
0.2 mg/kg. See Table 2-2 in the ROD.
7.
Page 12, Table 2a. The value for perchlorate for protection of groundwater should be
0.06 mg/kg.
The cleanup levels have been updated and corrected and were re-issued as part of
the OU 6 PP Extension notice (dated June 2013). The cleanup level for
perchlorate for the protection of groundwater is 0.06 mg/kg. See Table 2-2 in the
ROD.
8.
Pages 11-12, Table 2a. It is not clear how many of the values in the fourth column for
metals were derived for protection of groundwater. The fifth column provides the
source and there are instances where the reference is "background threshold value."
If one looks at the background values for those metals as established in 2006 by
Aerojet, the values are significantly different. Many are off by a factor of ten. In
addition, the maximum concentration of cadmium in background soils is 0.2 mg/kg,
so it is difficult to find where the 7 (of 0.7) mg/kg value was from.
The cleanup levels have been updated and corrected and were re-issued as part of
the OU 6 PP Extension notice (dated June 2013). See Table 2-2 in the ROD.
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment #
Comment
Response
9.
Page 13, Table 2-b. Sufficient information has not been provided to reader on how
these values will be used. Hie values are for the protection of human health from the
listed VOCs in ambient air. Location specific values will be used to determine site
specific values that will not cause ambient air (indoors and outdoors) to contain
concentrations of the listed VOCs to exceed the values listed in the table.
In addition, is it correct to state that protective soil vapor levels in the subsurface soil
are decreased by location and depth specific attenuation factors? From what
concentration will they be decreased from? Are trying to say that in applying the
values in the table site-specific attenuation factors will be used to establish cleanup
values in the subsurface and in doing so the subsurface cleanup values will be greater
than those shown in the table?
The commenter is correct that the proposed cleanup levels represent target indoor
air concentrations. The cleanup levels selected in the ROD (Table 2-3) are to
attain these specified protective levels in indoor air. Cleanup levels for SVE in
soil will be depth- and site-specific, and the method for calculating these levels
will follow DTSC guidance in the remedial design and remedial work plans. This
approach is consistent with the method currently being implemented in OU-5 at
the Site.
10.
Page 13, second column, first bullet. The text in this bullet causes us to ask the
question Under what circumstances would a site meeting the criteria not be
recommended for cleanup evaluation?
The non-retained areas that presented an unacceptable risk to HH, ecological
receptors, or groundwater are captured under the remedy for the overlapping
retained area. For example, the COCs for AW-N-11 posed a risk to groundwater
but this area overlaps with AW-R-7/R-14. Therefore, the COCs that pose a risk to
groundwater at AW-N-11 were included in the COC list for the protection of
groundwater at AW-R-7/R-14. Only the non-retained identification number of
AW-N-11 was not carried through to the PP and ROD, but the contamination and
risks associated with that non-retained area will be addressed.
In non-retained areas where it was agreed that the area did not pose a risk to HH,
ecological receptors, or groundwater, these areas and any areas within Aerojet
that overly groundwater contamination are required to have groundwater ICs.
These groundwater ICs are described in Section 2.10 of this ROD and are
expected to be included as part of the sitewide OU-1 ROD.
There are no areas within OU-6 that are considered "No Action" areas. Either
Alternatives 2, 3, or 4 were selected for an area, or the area will be covered by the
sitewide ICs.
11.
Page 14, first column, second bullet. What is meant by increasing concentrations?
Increasing with time, with depth, with distance ?
The text should have stated, "increasing with depth."
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment #
Comment
Response
12.
Page 14, Remedial Action Objectives. How will achievement of these Remedial
Action Objectives be determined? The objectives should be improved by applying
SMART criteria (ITRC, Integrated DNAPL Site Strategy, November 2011) to them.
The goal of applying the SMART criteria is to make the Remedial Action Objectives
specific, measureable, attainable, relevant and time-bound. In so doing, it is clear
if/when the objective has been complied with.
Taking the first Remedial Action Objective as an example, it was initially written in
the Proposed Plan as "Prevent exposure to COCs in soils that pose an unacceptable
risk for present and future workers and residents on the property and ecological
receptors on the property. This Remedial Action Objective lacks several of the
SMART criteria. Rewording the objective to: Prevent the exposure of present and
future workers and residents of the property to concentrations of contaminants in the
upper ten feet of soil exceeding those values found in Table 2a at the Source Areas
listed in Table 1. This will be done by excavating the soils or capping and land use
controls to prevent exposure. This meets all of the SMART criteria except
time-bound. As there is no timeframe established at this time, that criteria can be
added later. A similar objective would be established for ecological receptors and
contaminants in soil.
Remedial action objectives are specified in the ROD in Section 2.9. These
performance standards are also included in the ROD, and will be evaluated
during the completion report for the individual remedial action areas.
Commenter: Mr. Bill Busath, Engineering & Water Resources Manager, City of Sacramento (comments dated September 17, 2013)
1.
American River Cumulative Risk: EPA has previously indicated that there will be a
sitewide assessment completed once each Operable Unit has been individually
assessed, which will include an analysis of impacts to the America River. This will
evaluate the impacts of the various groundwater treatment discharges, in addition to
stormwater, seep flows, and perched groundwater from the Aerojet site. Cumulative
impacts on the American River are already occurring from both the Western
Groundwater and Perimeter Groundwater remedies. If any remedy implementation
from the BOU results in additional impacts to the American River then it needs to be
included in the cumulative analysis.
EPA will conduct a sitewide evaluation of the Aerojet site as part of the final,
sitewide Operable Unit 1. This evaluation will include human health and
ecological risk. The OU-6 ROD addresses risk to human and ecological receptors
from contaminated soils within the boundaries of OU-6. The OU-6 ROD also
evaluates soil sources for their potential to impact groundwater and, where
necessary, selects remedial actions to reduce migration of contaminants to
groundwater.
2.
American River Cumulative Risk: The City recommends incorporating minimum
river flows when determining suitability of increased discharges. We also
recommend that EPA evaluate surface water discharges and suitable river conditions
using quantifiable conditions such as river flow, precipitation, reservoir releases, and
other operational and hydrologic information rather than a general approach
assuming flows are higher during winter months, which is not always the case on the
American River.
No new discharges to the American River are proposed as part of the Selected
Alternative for OU-6. Treated groundwater is discharged as part of the remedial
action for the Western Groundwater (OU-3) and Perimeter Groundwater (OU-5)
OUs under permits issued by the Regional Water Quality Control Board.
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ippendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWQCB, Engineering & Water Resources, and Aerojet Rocketdyne
3.
American River Cumulative Risk: There continue to be areas of groundwater
contamination or surface runoff that are not well characterized for water quality.
Well development water and surface runoff from the Aerojet site should be
monitored appropriately to characterize its risk and not automatically classified as a
"low-threat" discharge under the Aerojet National Pollutant Discharge Elimination
System (NPDES) permit for the Groundwater Extraction and Treatment facilities
(GETs) and low threat discharges. Based on pages 6-7 of the Proposed Plan, it
appears that there is significant potential exposure of constituents of concern to
runoff. The City recommends that these flows be managed so as to not result in
contamination of storm water and non-storm water discharges.
GET effluent and industrial storm water from the Aerojet facilities are subject to
NPDES permit requirements under RWQCB Order No. R5-2013-0156. The
requirements are ARARs for the Selected Remedy.
4.
Exposure Pathways: The Plan and its supporting documents (Remedial Investigation,
Human Health Risk Assessment, and Feasibility Study) have identified recreational
use as the only exposure pathway from the surface water on the Aerojet site, and all
assessments were conducted based on that pathway. Many of the surface waters on
the Aerojet site are tributary to the American River which has a significantly broader
list of beneficial uses, including municipal and domestic use. The risk assessment did
not evaluate potential downstream, offsite impacts to municipal and other uses of the
American River. We are concerned that our offsite municipal use has not been
considered as part of the BOU risk assessment and identification of remedy options.
Discharges of treated groundwater effluent from the Aerojet site are regulated
under Waste Discharge Requirements and an NPDES permit issued by the
RWQCB Order No. R5-2013-0156. Table 4 of this permit identifies Basin Plan
Beneficial Uses applicable to Buffalo Creek and Alder Creek, and the permit
requirements are protective of these beneficial uses.
5.
Exposure Pathways: In addition, the recreational exposure pathway was not
quantitatively addressed since the projected activity was seasonal wading. This
minimized the potential impacts identified to risks for surface water exposure in
the BOU, including the final list of constituents of concern (COCs), and may
underestimate the impacts of surface water and proposed remedy options.
Surface water screening levels were developed in the OU-6 RI Section 3.1.4.
The selected SWSL for each compound was the lowest of the following:
The tapwater PRG (EPA, 2004);
The federal maximum contaminant level (MCL);
The California MCL; or
Dissolved concentration limits cited in the Revised Waste Discharge
Requirements for Aerojet General Corporation and Aerojet Fine
Chemicals (NPDES Permit No. CA0004111) (RWQCB Order No.
R5-1999-0016- R01, revised 2002).
These SWSLs included exposure pathways beyond seasonal wading.
6.
Exposure Pathways: Finally, the assessments for the Buffalo Creek and West
Lakes action areas only addressed soil and sediment media impacts, not the
potential surface water impacts. This seems to be a significant exclusion since the
surface water has great potential to be impacted by contact with the soils in the
waterbodies as well as the runoff flows from the site. Since these waterbodies are
tributaries to the American River, we are concerned about their lack of inclusion
for exposure pathways.
RWQCB Order No. R5-2013-0156 includes provisions for monitoring water
quality in Buffalo Creek and the West Lakes area to ensure protection of
beneficial uses of the receiving water.
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment #
Comment
Response
7.
Selected Remedies: The Plan includes various remedies, one being soil flushing.
This remedy was selected for three areas in the Line 2 Region. The Feasibility
Study indicates that the soil flushing remedy would target deeper contamination
areas that have the potential to impact groundwater and cannot be easily
remediated from the surface. The Feasibility Study indicates that this process
involves flushing water to extract constituents which is then recover from the
aquifer and treated at a GET facility.
Based on the Proposed Plan and the supporting documents the treated water is
expected to be recharged to groundwater locally. However, if this treated water is
discharged to surface water we request that a monitoring program be implemented
to identify the constituents of potential concern (COPCs) and ensure that adequate
treatment is in place to remove any compounds potentially impacting the American
River municipal and domestic beneficial use. The COPCs could include
constituents included in the supporting documents for the Proposed Plan, as well
as newly identified constituents of interest for drinking water.
In the event that extracted or treated groundwater is discharged to surface
water, a monitoring program that complies with the substantive requirements
of NPDES will be implemented.
8.
Constituents of Concern: The EPA's stated primary objective for this Proposed
Plan is "to protect public health and the environment from contaminants found in
soils and soil gas from sources within the BOU". We agree that this is the intent of
the remedy, but if drinking water Maximum Contaminant Levels (MCLs) are the
basis for cleanup levels, then the remedy is actually only meeting acceptable levels
of risk in drinking water as defined by EPA. Whenever feasible it is preferred to
further reduce the risk to public health, so we support the use of California Public
Health Goals (PHGs) and EPA Maximum Contaminant Level Goals (MCLGs)
where appropriate for the Superfund cleanup.
Comment noted.
9.
Exposure Pathways: The Remedial Investigation identified COPCs for human
health. Seventy-five constituents were excluded from the investigation because
they were non-detectable, but they had reporting limits higher than the human
health screening levels. We are concerned that these constituents may be present in
the waters at levels of concern, and we recommend that they should be monitored
in the future as part of the remedy implementation. Moreover, due to the long
length of time for the cleanup it is important that requirements are kept up-to-date
with the latest drinking water standards, analytical detection limits, and new
information on contaminants.
The Selected Remedy will be subject to a review process every five years in
accordance with CERCLA that includes a review of site monitoring data and
evaluates whether the Selected Remedy remains protective.
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment #
Comment
Response
10.
Monitoring and Reporting: The City acknowledges the helpfulness and
information provided by Aerojet staff over the past years in providing notification
of NPDES permit exceedances for the GETs. The Proposed Plan should require
continued notification procedures to contact downstream water purveyors of
permit exceedances, monitoring results that exceed MCLs, detects found in the
American River, or any significant problems or failures with the discharge or
remediation activities. The notification needs to occur in a timely manner to allow
water utilities the ability to respond to changes in source water quality to protect
public health. The discharge also should be suspended immediately if potential
significant issues arise, until the risk is removed. This is essential to ensure
protection of public health.
The NPDES discharge requirements applicable to the GETs are not affected by
the ROD and are not changed by the OU-6 selected remedy.
11.
Monitoring and Reporting: Detection limits, methods, constituents or other factors
should be reviewed to ensure that collected data provides appropriate information
to assess impacts to human health. These parameters should be adjusted to keep
current with future water quality standards and guidelines and available laboratory
technology. The monitoring program should include an expanded list of all
COPCs, including those removed for nondetectability if analytical methods can
provide data at lower levels, on a reasonable frequency to ensure that if present at
levels of concern additional chemicals of concern are identified and addressed as
part of the current remedy.
OU-6 (and the entire Aerojet Site) will be subject to a Five Year Review that
will periodically evaluate the protectiveness of the selected remedy. This
evaluation will include an assessment of changes in standards that could affect
short- or long-term protectiveness and recommend necessary actions.
12.
Monitoring and Reporting: The implementation of the remedy should include
ongoing monitoring, inspections, evaluation of site conditions, including the
physical equipment utilized for the cleanup to ensure that it is functioning
correctly, and safety assurances such as alarms and backup power.
Ongoing monitoring and inspection of physical components of the remedy is
required as part of the Selected Remedy.
Commenter: Mr. Peter Kvam, Project Coordinator, Aerojet Rocketdyne (comments dated September 20, 2013)
General
Comment
It is unclear why the Line 2 and Line 5 actions were proposed for excavation rather
than no action or capping to the extent of protection of groundwater. We note that
it is possible that the agency may have considered the potential that the areas might
be subject to development in the future which might make capping a less feasible
alternative. Hie description of the "planned use" in the proposed plan was based
upon preliminary land use planning that has not undergone local agency review or
final land use planning. Accordingly, future land use may not involve "mixed use"
or "residential" use in the locations but may involve roadways or open space which
can more easily accommodate capping or require no action. Accordingly, the
remedy selected for these areas should not assume a particular use, but provide for
institutional controls that establish the action (e.g., excavation or capping, or no
further action) when the property is being developed.
EPA is required by policy to consider the Reasonably Anticipated Future
Land Use in remedy selection. This assessment was conducted in part using
information from the OU-5 and OU-6 Reuse Assessment (2010) that indicates
the Line 2 and Line 5 North areas are located in areas proposed for future
residential and mixed-use development as part of the Westborough Phase 2
development. Given the uncertainties associated with the location of specific
features of future development such as roadways and other infrastructure,
EPA is selecting the excavation alternative to remove the contamination and
eliminate the need for long-term tracking and management of these areas used
engineering and/or institutional controls.
14 OF 20
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment # Comment Response
1.
Administration Area East - AE-SV-R-4 and AE-SV-R-5: Table 1 identifies the
selected remedy for AE-SV-R-4 and AE-SV-R-5 as Alternative 4 - Source
Removal/Reduction (SVE).
AE-SV-R-4 - PCE was detected in soil vapor at location A20-RC29-SP01 at
concentrations that indicate a potential high risk to groundwater; however, PCE is
not present in groundwater beneath this area at concentrations that exceed
beneficial uses. This area is currently capped with an asphalt parking lot (except
for the north-south trending drainage ditch). Any release in this area is estimated to
have occurred over 30 years ago. Therefore, although PCE is present in soil vapor,
PCE is not migrating to groundwater under current conditions (capped).
Alternative 3, (institutional controls and capping) is appropriate for this area and
should be proposed to protect groundwater from becoming impacted by PCE in
soil vapor.
AE-SV-R-5 - The remedial action proposed appears to be based upon the
detection of two chemicals [tetrachloroethene (PCE) and trichloroethene (TCE)]
in soil vapor. However, soil vapor samples were collected from three depths at
this location. Concentrations of both compounds decreased with depth. The
concentrations of both compounds detected in the deepest soil vapor samples
(30 feet bgs) did not pose a risk to groundwater. In addition, neither TCE nor PCE
were detected in groundwater at concentrations indicating an impact to
groundwater from the release of TCE or PCE from this location. This data suggests
that as long as the areas remains capped, the chemicals in soil vapor are not likely
to migrate vertically and impact groundwater. While the incremental lifetime
cancer risk to commercial/industrial workers was calculated, it was less than 1 x
10-4 (maximum 2x10-5) and the building is only used for storage of supplies and
is not occupied continuously. Accordingly, this is a location where the evaluation
of risk clearly supports Alternative 3 (capping and institutional controls).
The preferred alternative is mass removal using SVE. This method is preferred
for VOCs because it eliminates the source to groundwater.
FS Table 1-14 summarizes results of the risk assessment for these locations.
Both indicate a potential risk to groundwater based on soil vapor sampling
results and groundwater contours. The table in Appendix B of the ROD
summarizes the risk and rationale for remedial action in these areas. The
distance between the R-4 and R-5 sampling locations does not allow
discernment of whether these sources are contiguous. Pre-design sampling as
part of the remedial design will be used to determine the specific extent of SVE
in this area.
Additionally, the 2 x 10"5 risk to HH for commercial/industrial warranted an
evaluation of remedial alternatives at this location, and the selected remedy
would use SVE to permanently remove VOCs to reduce risk to future site
occupants. In addition, the extent of contamination is not fully defined at this
time. The current use of a storage/supply building cannot be guaranteed as part
of a capping remedy.
2.
Line 2: L2-R-4, L2-R-5, and L2-R-9
Table 1 identifies the selected remedy for L2-R-4, L2-R-5, and L2-R-9 as
Alternative 4 - Source Removal/Reduction (Excavation with Flushing and
Air Stripping). It is not clear what EPA is proposing in the PP. Soil flushing for
perchlorate, with down-gradient groundwater extraction with treatment for
perchlorate and VOCs is an appropriate remedy. It appears, however, that the
remedy being proposed may require excavation (not clear whether excavation
occurs before or after flushing of the soil column) in the same locations as the soil
flushing. There is no basis for requiring excavation down to 12 feet bgs before the
soil flushing. Soil flushing, if a viable remedy for soils deeper than 12 feet, should
also be a viable remedy for soils from the surface to 12 feet bgs. Perhaps, EPA
The extent of contamination for soil and soil vapor has not been defined in
these areas and the soil retained areas (R-4, R-5, and R-9) are all in close
proximity to one another - less than 100 feet apart. L2-SV-R-2 completely
overlies all three soil areas. The commenter is correct that EPA intends to use a
combination of methods to meet remedial goals in these areas. The specific
approach and sequencing will be set forth in the remedial design, but it is
anticipated excavation would be used to the extent necessary to allow for
effective implementation of the soil flushing method. Remediation of VOCs
from soil gas would be accomplished using SVE until remedial goals are met.
15 OF 20
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment # Comment Response
anticipated that there would be some excavation (e.g., first 2 feet bgs) to create a
berm so as to allow ponding of water for soil flushing. The extent of such
excavation for flushing would be based upon site specifics and would be
specifically described in the remedial design. However, there would be no basis for
excavation to 12 feet below ground surface for the protection of groundwater,
when the intent is to flush the chemical to groundwater.
Requiring excavation, when unnecessary, does not simply add a monetary cost.
For example, using EPA's carbon footprint calculator, excavation to 12 feet bgs
over a 0.25 acre area (roughly the size of L2-R-4, L2-R-5, and L2-R-9) results in
over 180 tons of C02 into the environment (the equivalent of the average annual
C02 emissions from over 15 homes) (http://www.epa.gov/cpd/pdf/brochure.pdf).
The proposed passive remedy with minimum excavation would result in less than
10% of the tons of C02 into the environment.
AR recommends allowing the flexibility to evaluate flushing for perchlorate, with
downgradient groundwater extraction with treatment for perchlorate and VOCs
prior to making a decision whether to excavate or cap thereafter. The decision to
excavate or cap would be based upon the success of soil flushing in reducing the
perchlorate concentration to a concentration that poses an acceptable risk to human
health and the environment.
3.
Line 5N - L5-R-3 and L5-R-4
Table 1 identifies the selected remedy for L5-R-3 and L5-R-4 as Alternative 4 -
Source Removal/Reduction (Excavation). It further identifies the risk driver as
threat to groundwater. The remedy is not appropriate for the following reasons.
L5-R-3 is represented by one sample location (52E-SB05). Soil samples were
collected from depths of 1.0 foot, 5.5 feet, and 11 feet bgs from this location.
The 1.0 foot bgs samples contained 260 |ig/Kg perchlorate, which is above the
protection of groundwater screening level of 60 |ig/Kg; however, concentrations
decrease with depth. The 5.5 foot bgs soil sample contained 56 |ig/Kg, which is
below the protection of groundwater screening level and the 11 foot bgs samples
did not contain perchlorate above the detection limit (5.3 (ig/Kg). Therefore,
perchlorate is not migrating vertically toward groundwater and is not posing a risk
to groundwater.
Please also see our introductory note on land use and remedy selection. Because
the area is within an area that is ultimately planned for development that could
include new uses and activities, the remedy here should be institutional controls to
establish evaluations/actions to be taken should such development occur.
The planned future use for this area includes mixed use and residential use.
The community has expressed a great deal of concern during the public
comment period on the PP regarding removal of perchlorate in shallow soils in
areas that may be used for residential reuse. In light of this concern, and the
presence of COCs above cleanup goals, this area is selected for excavation to
permanently remove these COCs. Institutional controls are not appropriate for
this area given the accessibility of the contaminated soils and redevelopment
plans.
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment # Comment Response
4.
Line 5N - L5-SV-R-1 and L5-SV-R-2
Table 1 identified the selected remedy forL5-SV-R-l andL5-SV-R-2 as
Alternative 4 - Source Removal/Reduction (SVE). It further identifies that risk
driver as threat to groundwater. Each of these locations is represented by a single
sample location 52E-SP07 and 51E-SP11, respectively. Each of these locations
exceeds the protection of groundwater screening level by a factor between lOx
and lOOx. However, the concentration of VOCs in groundwater is low (maximum
concentration is 13 jug/L) and there are 10 locations surrounding these two
samples. None of the samples (total of 15 samples) collected from these 12
locations contained VOCs above the groundwater screening level. Additionally,
the release in this area occurred over 30 years ago. Since this area is not capped, it
is not likely that current VOC concentrations would result in higher groundwater
concentrations in the future. Therefore, since the extent of soil vapor impact is
small, the VOCs have been in soil for over 30 years, the concentrations of VOCs
in groundwater are low, and the groundwater is captured downgradient by PGOU
extraction systems, SVE is not warranted in this area.
It is possible that the Agencies took future development plans into their evaluation
when determining the need for remedial action in these areas. Both of these
remedial areas are encompassed by L5-SV-R-3, which requires institutional
controls if land use changes to residential in the future; therefore, these
institutional controls are appropriate and SVE is not appropriate.
Because this area has been identified as planned for residential development,
EPA believes SVE is warranted based on the currently available data even
though GW has not been impacted. As stated, the release is many decades old,
it may be prudent to collect additional characterization data to further delineate
the lateral extent and confirm the presence of contamination. If, after additional
data are collected, the VOCs are shown to not pose an unacceptable risk to
human health and the environment, then the selected remedy may be
reassessed.
5.
Chemical Plant 2 - CP2-SV-R-1 through CP2-SV-R-5
Table 1 identities the selected remedy forCP2-SV-R-l through CP2-SV-R-5 as
Alternative 4 - Source Removal/Reduction (SVE). It further identifies the risk
driver as human health. Chemical Plant 2 is not within any current proposed
development planning area. There is no evidence of any near term construction of
new facilities on this site. AR currently anticipates that the former Chem Plant 2
area will be used as buffer/open space between AR and future development areas.
Accordingly, institutional controls are appropriate and SVE not appropriate.
COCs in this area present high levels of risk to industrial/commercial and
residential use. SVE (Alternative 4) was selected to meet EPA's preference for
treatment.
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment #
Comment
Response
6.
Administration Area East - AE-R-8
Table 1 identifies the selected remedy for AE-R-8 as Alternative 4 - Source
Removal/Reduction (Excavation). It further identifies the risk driver as human
health. Excavation under the building would disrupt ongoing operations.
Additionally, the area around the building is currently capped. Since excavation of
soils outside the building would still require a deed restriction to maintain the
building as a cap and excavate the soils at the time the building is destroyed, AR
recommends an institutional control that requires capping and requires excavation
only should the building is demolished. The existing cap should be enhanced and
maintained to reduce infiltration of surface water.
In the ROD, EPA finds that removing the contamination in this area to
remedial goals protective of industrial/commercial use is preferable to capping.
It is understood the removal of contamination that is under or near the existing
structure will not be accomplished until the building is removed.
Specific Comments on the PP from Mr. Peter Kvam, Project Coordinator, Aerojet Rocketdyne (an attachment to the comments dated September 20, 2013)
1.
Page 6, second paragraph - It is inaccurate to state that 5900 acres of the 8500 acre
property are potentially contaminated. Most of the land is open space between
operating areas and is not impacted by chemicals released during Aerojet
operations. Aerojet suggests that should EPA require a description in the ROD, it
would be more accurate to state:
As part of the 2001 Stipulation and Order Modifying Partial Consent Decree, the
site M'as divided into OUs to expedite remedy implementation and through
operable unit Remedial Investigations/Feasibility Studies and remedy selection as
to potentially contaminated areas of surface and surface soil within the remaining
5,900 acre NPL site.
The text in Section 2.3 of the ROD includes revised text as suggested.
2.
Page 6, Site Characteristics, 4th paragraph, last sentence. Population is
underestimated. According to 2010 census data, the population of Rancho Cordova
(64,776) and Folsom (72,203) totals approximately 137,000.
The surrounding cities and communities population data have been updated in
the ROD in Section 2.1.
3.
Page 6, Site Characteristics, 5th paragraph, first sentence. The Boundary Operable
Unit is located along the northern and western boundaries of the Aerojet Superfund
Site, not the Aerojet property.
The text in Section 2.1 of the ROD includes this corrected description.
4.
Page 10, Site Characteristics, Chemical Plant 2 Area, 3rd sentence. Should state
that pesticides were manufactured at this chemical plant. This will help support the
statement that episodic wastewater disposal from the Chemical Plant 2 area
resulted in the presence of pesticides in the Dredge Pit and Eastern Basin.
The text in Section 2.1 of the ROD includes this information, as suggested.
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment #
Comment
Response
5.
Page 10, Site Characteristics, 2nd paragraph, last sentence. Hie sentence does not
make sense. It should be removed. "High concentrations of VOCs in soil gas in
portions of the Chemical Plant 2 area are the only principal threat wastes identified
in the Boundary Operable Unit".
The ROD text will not repeat this sentence.
6.
Page 10, 5tli paragraph. Open Space Areas within the BOU were evaluated to
determine the potential that there might be a source through the use of aerial
photograph reviews. If aerial photography showed the potential for activities
within open space areas, soil and soil vapor samples were collected.
Text has been added to Section 1.1 that states all potential sources of
contamination were investigated during the RI.
7.
Page 10, 6th paragraph, "Chemical Plant 2 Are" should be "Chemical Plant 2
Area".
The typographical error will not be repeated in the ROD.
8.
Page 10, Summary of Site Risk, first paragraph, 5tli sentence. To bound the risk to
human health, the text could be more accurate by stating ".. .from direct contact
with contaminated soils from 0-12 feet below around surface..."
This information is included in the ROD in section 2.7.2.
9.
Page 10, Summary of Site Risk, first paragraph, 5th sentence. To bound the risk to
ecological receptors, the text could be more accurate by stating ".. .evaluated risks
to ecoloaical receptors from exposure to constituents in soil from 0-6 feet below
around surface..."
This information is included in the ROD in section 2.7.5.
10.
For areas where soil vapor extraction is the preferred alternative, the PP needs to
state that due to the presence of VOCs in groundwater up-gradient of the BOU
source, cleanup to the cleanup levels for ambient air (Table 2) may not be
achievable until after the remedy of up-gradient sources.
Text in Section 2.10.4 of the ROD clarifies that ECs will be required if RAOs
are not met by SVE.
11.
AE-SV-R-3 is not shown on Figure 3
This area is now shown on figures in the ROD.
12.
AW-SV-R-1 is not shown on the Figure 3.
This area is now shown on figures in the ROD.
13.
L2-SV-R-1 is not shown on the Figure 4.
This area is now shown on figures in the ROD.
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Appendix E-2. Written Comments
Appendix E: Responsiveness Summary to OU-6 Proposed Plan Comments
Responses to Comments from DTSC, Carmichael Water District, CVRWOCB, Engineering & Water Resources, and Aerojet Rocketdyne
Comment #
Comment
Response
Comment from Mr. Ronald Keil, Ph.D. in a letter dated May 12, 2013.
1.
I am writing in reference to the Aerojet General cleanup site in Rancho Cordova,
CA. I have information on just one significant spill of TCE at the site and am
writing on the chance that the information will have some bearing on the Aerojet
Boundary Operable Unit 6 Proposed Plan. I just happened to have thought of the
Aerojet site today and while searching the Web came upon the ongoing cleanup.
I started work at the Sacramento plant in July of 1963, a Mechanical Engineer
fresh out of San Jose State and after a brief introductory rotation was assigned to
the Solid Rocket Plant.
In 1964 or 1965 there was a strike by the Machinists' Union and many of us
engineers were reassigned temporarily to production duties. I worked for these
several weeks at a motor insulating facility in Building 10, at the far northwest
comer of the Aerojet property. In this facility the motor casings received both
molded insulation caps and poured rubber insulation. In the process the casings
were cleaned in a TCE vapor-degreasing vat located below ground level. This
operation left the TCE contaminated with pigment from the primer coating and
needed periodically to be sent to a facility to be re-refmed.
When the used chemical was to be sent out it was supposed to be pumped into a
holding tank and later transferred to drums on the loading dock. That is what the
process documentation stated, but apparently the regular workers had changed the
plumbing to direct the flow directly to the loading dock. Unfortunately they had
not changed the documentation. As our crew pumped the TCE supposedly into the
holding tank there came a hue and cry from outside; the chemical was being
pumped into a drum, which overflowed for several minutes before being
discovered. We shut down the pump and checked outside to see the entire parking
lot covered by a layer of red primer-laden TCE. I estimate that several hundred
gallons of the chemical were thus spilled.
That was the only chemical spill to which I was a witness, and of course at the
time nobody appreciated the toxic effects of the material. It was just left to soak
"harmlessly" into the tailings. I've thought about it a number of times through the
years and now am glad to report the spill to an agency that cares.
I took a leave of absence from Aerojet in 1966 to return to school at UCD, then the
next year left permanently. I have had no tiling to do with Aerojet since then,
though some of my fellow students worked summer internships there.
Based on the information in this comment, EPA believes the referenced
process occurred at Line 03, Building 03010 (Final Assembly and Palletizing
Building). This area is located in the Island OU, Source Area 1 IF, and will be
investigated in the RI/FS for the Island OU.
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enclii I
I I ' I etter to Community tui'M cciiibi i '"ill 'i
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION IX
73 Hawthorne Street
San Francisco, CA 941 OS
December 5, 2012
Ms. Jams Hepel, Chair
Community Advisory Group
Aerojet General Corp. Super fund Site
4507 Marion Court
Sacramento, CA 95822
SUBJECT; Community Advisory Group Comments, Final Boundary OU RI Report
Dear Ms. Hepel:
We thank you and members of the Community Advisory Group (CAG) for reviewing and
providing comments to the Final Remedial Investigation report for the Boundary Operable Unit at
the Aerojet Superfund Site, The remedial response for this site is being conducted by the
potentially responsible party under a Consent Decree with EPA and the State of California, As
such, EPA directed Aerojet to provide the CAG with a response to your comments. This response
is transmitted under separate cover by Aerojet.
Two specific issues have been raised in discussions at prior CAG meetings, and members of the
community requested that the Agencies (EPA, California Department of Toxic Substances
Control, and the Regional Water Quality Control Board) provide clarification and a response to
these specific comments. These areas concern:
Comment 2 and Comment 3 regarding the vapor intrusion pathway and trichloroethyl ene,
and
Comment 11 regarding calculating the potential (or "estimated") perchlorate exposure
through the home gardening pathway.
The Agencies' project managers and toxicologists have reviewed the comments, conducted
additional discussions with the CAG, and provide the attached responses.
We appreciate CAG members' interest and expertise as it informs the Superfund remedial process
at this site, and value such input as the process moves forward. As you are aware, there will also
be a formal public comment period on EPA's forthcoming Proposed Plan for the Boundary
Operable Unit.
Page 1 of2
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Should you have any questions on this correspondence, please contact me at (415) 972-3003,
Alex Macdonald at (916) 464-4625, or Steve Ross at (918) 255-3694.
Sincerely,
>7V -
Gary J.^Riley, P.E.
Remedial Project Manager
cc: Sieve Ross, DTSC
Alex Macdonald, RWQCB
Chris Fenncssy, Aerojet
Page 2 of 2
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Comment 11. Perchlorate Exposure through the Home-Gardening Pathway: The CAG has concerns
with the US EPA response regarding the quantitative evaluation of exposure to perchlorate via the
home gardening pathway.
EPA/ Regulatory Response: Since the March 2012 AJ CAG meeting, EPA/regulatory agencies have been
researching this Issue further, and have identified a field study that could be used to estimate a
bioaccumulation factor (BAF) for leafy vegetables. When we met in March, the biggest concern with the
studies that were discussed were that the artificial conditions in a laboratory setting made it difficult to
extrapolate these results to the field. In these lab studies, plants were not exposed to a continuous
perchlorate concentration (a single spiking was used) and were grown in artificial media containing
hydrosol, a colloidal suspension that is different than soil.
More recently, a literature search identified a study (Ellington et al., 2001) that was conducted in the
field, included a continuous source of perchlorate in soils (loamy sand), and exposed plants throughout
the growing season. This study noted that leafy plants provided the greatest estimate of a BAF (282 or
300 rounded), consistent with the lab studies (Yu et al., 2004).
To estimate a consumption rate (CR) for lettuce and other leafy vegetables, the agencies referred to the
most recent version of EPA's Exposure Factors Handbook (2011)
http://cfpub,epa.gov/neea/risk/recordisolav.cfm?de1d=236252 . The CR for lettuce and leafy
vegetables was summed for "consumers" of lettuce and leafy vegetables. For a 70 kilogram adult, the
CR is estimated to be S40 grams (70kg x 1.1 g/kg-day x 7 days) or 1.2 pounds per week. Similarly, for a
15 kilogram child, the CR is estimated to be 160grams (15kg x 1.5 g/kg-day x 7 days) or approximately
1/3 pounds per week. This is a total consumption rate. For home gardeners, a high-end dietary fraction
of 0.40 is recommended in EPA Exposure Factors Handbook and EPA Soil Screening Guidance
http://www.epa.gov/superfund/health/conmedia/soll/index.htm.
Although the agencies recognize that there are still significant uncertainties with respect to an Aerojet-
specific plant BAF for perchlorate, we have calculated a soil-screening level that we believe will be
protective of the home-gardening pathway. Please find the calculations in the attachment. Using
available guidance, EPA/regulatory agencies derived a residential soil screening level for the soil-
plant-human exposure pathway of SO ppb perchlorate for children and 90 ppb perchlorate for women
of child-bearing years.
Literature Cited
Ellington, JJ, NL Wolfe, AW Garrison, JJ Evans, JK Avants, and QTeng, 2001. Determination of
Perchlorate in Tobacco Plants and Tobacco Products. Environmental Science and Technology, Vol. 35,
3213-3218.
Yu, L, JE Canas, GP Cobb, WA Jackson, and TA Anderson, 2004. Uptake of Perchlorate in Terrestrial
Plants. Ecotoxicology and Environmental Safety, Vol 58, Issue 1 pp. 44-49.
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Calculation of a Perchlorati Screening Level for Soil-Plant-Human Exposure Pathway
Acceptable dally Intake (I)
I (mg/kg-day) = HQ x RfD x AT x 365 davs/vr
EDxEF
Parameter (unit) Value (reference)
HQ/target hazard quotient (unitless) 1 (USEPA RAGS)
AT/averaging time (years) 2 (3 -5 year old child)
36 (13 - 49 year old female)
ED/exposure duration (years) 2 (3 - 5 year old child)
36 (13 - 49 year old female)
EF/exposure frequency (days/yr) 350 (USEPA RAGS)
RfD/oral reference dose 7 x 104 mg/kg-day (USEPA IRIS)
I = 1 x 7 x 10"4 mg/kg-day x 2 (or 36Wr x 365 dav/vr = 7,3 x 10"4 mg/kg-day
2 (or 36) yr x 350 day/yr
Soil Screening Level (SSL)
SSL (mg/kg) = I x 1000 g/kg
FxCRxDWx BAF
Parameter (unit)
l/acceptable daily intake (mg/kg-day)
F/fraction of vegetables assumed to be
contaminated (unitless)
CR/vegetable consumption rate (g/kg-day)
DW/wet to dry weight conversion factor
BAF/soil-to-pIant bloaccumulation factor
Value (reference)
7.3 x 10"4
0.4 ("high end", EPA SSL Guidance 1996)
1,5 (3 -5 year child "consumer" of lettuce + leafy
vegetables in EPA Exposure Factors Handbook 2011)
1.1 (13 - 49 year female "consumer" of lettuce +
leafy vegetables in EPA Exposure Factors 2011)
0.063 (average of lettuce + spinach in EPA SSL
Guidance 1996)
300 (Ellington et al. 2001)
SSLcwu = 0.060 mg/kg or 60 ug/kg perchlorate SSUwun = 0.090 mg/kg or 90 ug/kg perchlorate
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Comment 2. The GAG is concerned that the proposed soil gas to indoor air attenuation
factor of 0.001 (RI Section 3.1.1.1 and RI Table 3.1-1) is not sufficiently
conservative to represent residential, buildings. EPA's Vapor Intrusion
Database: Evaluation and Characterization of Attenuation Factors for
Chlorinated Volatile Organic Compounds and Residential Buildings,
shows that an attenuation factor of 0.001 is sufficient to cover only about
20 to 40% of existing residential structures, depending on the database
screen used (EPA, 2012; Available at http://www.epa.gov/oswer/
vaporintrusion/documents/OSWER 2010 Database Report 03-16-
2012 Final.pdf, See Table 8 and Figures 17 to 20). A soil gas to indoor air
attenuation factor of about 0.3 {range of 0.097 to 0.6) would be required to
include 95% of existing residential structures (see Table 8). The relatively
coarse soils on much of the Boundary OU site would also tend to decrease
the attenuation of vapors from soil gas to indoor air. Attenuation of
vapors from soil gas to indoor air would likely be greater where ground
water is deep but less where ground water is shallow. While these
estimates are for existing residential structures, as new construction ages
it will also develop foundation cracks and other points of entry for vapors
from the soil below.
These empirical studies by EPA show less attenuation of vapors from soil
gas into indoor air than the default DTSC soil gas to indoor air
attenuation factor of 0.001, e.g. 1E-03, used in the RI. The CAG
recommends using multiple lines of evidence to establish soil gas to indoor
air attenuation factors that are protective of at least 90% of the residential
structure population to calculate Soil Vapor RI Screening Levels (RISL).
The CAG has raised this issue at previous CAG meetings.
Also note that the U.S. EPA's Vapor Intrusion Database shows that a
groundwater to indoor air attenuation factor of 1E-04 is protective of only
about 50% of the population (Figure 5, Data Set 2). A soil gas to indoor
air attenuation factor of about 1E-03 would be required to be protective of
about 90% of the population (EPA, 2012, Figu re 9, Data Set 2).
Comment 3. Since AJ used a soil gas to indoor air attenuation factor (of 0.001) that
studies by US EPA show to be overly optimistic to calculate Soil Vapor
RISL, the CAG has concerns with the Soil Vapor RISLs shown in Table
3.1-1. The CAG recommends that these be recalculated with attenuation
factors that are protective of at least 90% of the population as shown in
the EPA's 2008 study or use multiple lines of evidence to establish soil gas
to indoor air attenuation factors for the site.
a) Trichloroethylene (TCE): The CAG does not agree with the RI Soil gas
Screening level of 961 ug/m3 TCE. The CAG is concerned that the
protective Soil vapor screening level is far lower than the soil vapor SL
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used in the Rl. EPA published new toxicity criteria for TCE
September 28, 2ฎ 11 (See http://www.epa.gov/IRlS/subst/
G199.htm#refiiihal), and lias also published updated RSl.s for TCE
(See hr
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Further, it Is noted that there are regional differences in vapor intrusion which are not accounted for in
EPA's national database. According to California DTSC guidance (2011, Appendix B) DT5C averaged the
OEHHA attenuation factors for 16 volatile organic compounds, including ethyl benzene (Cal/EPA, 2010)
but excluding mercury and tetraethyl lead. The average attenuation factors for existing and future
residential buildings are 0.002 and 0.001, respectively.
As Aerojet has indicated, the residential risk of VI is primarily due to contaminated shallow groundwater.
In general, soil gas screening values are used at locations where VOCs were observed at "source areas"
where VOCs were spilled on the ground. To prevent vapor intrusion in existing and future residential
structures, the feasibility study will evaluate controls for vapor intrusion that will be required In areas
where the TCE concentration in shallow groundwater exceeds 5 ppb plus a 100-foot buffer.
EPA's recent health risk assessment of TCE concluded that TCE fs more toxic than previously believed. It
is understandable that given this new information, that the CAG would question whether the 5 ppb level
for TCE in groundwater plus a 100-foot buffer is still protective for indoor air exposures. Taking into
account the new toxicity/mutagenicity Information for TCE, both DTSC HERO and EPA Region 9 used the
default Johnson and Ettinger (J&E) model with residential parameters to estimate potential indoor risks
and concluded that a groundwater concentration of 5 ppb TCE at 30-foot depth (the shallowest depth
observed at Aerojet site) would be unlikely to pose a lifetime risk greater than one in a million.
Recently, Aerojet has updated some of its risk estimates for the Boundary OU, taking into account EPA's
new health risk assessment of TCE toxicity. The agencies are currently reviewing this information. It is
further noted that Aerojet has updated the White Paper on how to perform Human Health Risk
Assessments. Within that document it is stated that future risk assessments will utilize the most current
toxicity criteria, including the recent update to TCE.
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