PALOS VERDES SHELF
OPERABLE UNIT 5 of the
MONTROSE CHEMICAL CORP.
SUPERFUND SITE
FEASIBILITY STUDY
MAY 2009
REGION IX
U.S. ENVIRONMENTAL PROTECTION AGENCY
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Palos Verdes Shelf Superfund Site
Operable Units of the Montrose Chemical Corp. Superfund Site
Final Feasibility Study
May 2009
Prepared by
U.S. Environmental Protection Agency
Region IX
75 Hawthorne Street
San Francisco, CA 94105
CH2M Hill, Southern California Regional Office
Innovative Technical Solutions, Inc.
Walnut Creek, CA
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TABLE OF CONTENTS FEASIBILITY STUDY MAY09
Table of Contents
Section Page
Acronyms and Abbreviations V
Executive Summary ES-1
1.0 Introduction 1-1
1.1 Purpose and Organization of the Report 1-1
1.2 Background Information 1-2
1.2.1 Site Description 1-2
1.2.2 Site History 1-7
1.2.3 Summary of Remedial Investigation Report 1-8
1.2.4 Present Distribution of Mass of DDTs & PCBs 1-19
1.2.5 Sediment Transport and Fate 1-20
2.0 Risk Assessments & Predictive Modeling of Future Conditions 2-1
2.1 Summary of Risk Assessments 2-1
2.1.11999 Human Health Risk Evaluation 2-5
2.1.2 2006 Supplemental HHRE 2-4
2.2 2002/2004 Coastal Marine Fish Contaminants Survey 2-9
2.2.1 Survey Design 2-10
2.2.2 Summary of Data 2-13
2.2.3 LACSD vs. Fish Survey Comparison 2-15
2.3 Ecological Risk Assessment 2-21
2.3.1 Purpose and Scope of Ecological Risk Assessment 2-21
2.3.2 Bioaccumulation Modeling 2-22
2.4 Predictive Model of Natural Recovery 2-24
2.4.1 Summary of 1994 Predicitve Modeling of Natural Recovery 2-24
2.4.2 1996 Supplement to the Expert Report 2-33
2.4.3 Ongoing Refinements of the Predictive Model 2-35
2.4.4 Ambient Water Quality Forecasting 2-36
3.0 Remedial Action Objectives & Development of Remediation Goals 3-1
3.1 Development of Remedial Action Objectives 3-1
3.1.1 Media and Chemicals of Concern 3-1
3.1.2 Risk Assessments 3-2
3.2 Applicable or Relevant and Appropriate Requirements 3-4
3.2.1 ARARs Overview 3-4
3.2.2 Chemical-Specific ARARs 3-5
3.2.3 Location-Specific ARARs 3-7
3.2.4 Action-Specific ARARs 3-8
3.3 To-Be-Considered (TBC) Criteria and Other Potential Requirements 3-9
3.3.1 To-Be-Considered Criteria 3-9
3.3.2 Other Potential Requirements 3-11
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TABLE OF CONTENTS FEASIBILITY STUDY MAY09
Section Page
3.0
3.3.3 Summary of Potential Remediation Goals 3-12
3.4 Remedial Actions Objectives 3-12
3.4.1 Human Health Risks 3-12
3.4.2 Ecological Risks 3-13
3.4.3 WaterQuality 3-13
4.0 Identification of General Response Actions & Screening of Remedial
Technologies 4-1
4.1 Description of General Response Actions (GRAs) 4-1
4.2 Summary of Technology Screening Process 4-2
4.2.1 Screening Criteria 4-3
4.3 Evaluation and Screening of Remedial Technologies 4-5
4.3.1 No Action 4-5
4.3.2 Institutional Controls 4-5
4.3.3 Monitored Natural Recovery 4-8
4.3.4 Enhanced Monitored Natural Recovery 4-12
4.3.5 Containment 4-13
4.3.6 Removal 4-19
4.3.7 Ex Situ Treatment 4-24
4.3.8 In Situ Treatment 4-24
4.4 Summary of Retained Technologies 4-26
5.0 Development and Screening of Alternatives 5-1
5.1 Introduction 5-1
5.2 Alternative Development 5-1
5.2.1 No Action 5-2
5.2.2 Institutional Controls & Monitored Natural Recovery 5-2
5.2.3 Small Cap with Monitored Natural Recovery & Institutional Controls .. 5-9
5.2.4 Containment with Institutional Controls & Monitored Natural
Recovery 5-15
5.2.5 Removal with Institutional Controls & Monitored Natural Recovery ... 5-28
5.3 Screening of Alternatives 5-31
5.3.1 Alternative 1—No Action 5-31
5.3.2 Alternative 2 —Institutional Controls & Monitored Natural Recovery 5-32
5.3.3 Alternative 3 —Small Cap with Monitored Natural Recovery &
Institutional Controls 5-32
5.3.4 Alternative 4 —Containment with Monitored Natural Recovery
and Institutional Controls 5-33
5.3.5 Alternative 5 — Removal with Monitored Natural Recovery &
Institutional Controls 5-34
5.4 Summary of Retained Alternatives 5-35
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TABLE OF CONTENTS FEASIBILITY STUDY MAY09
Section Page
6.0 Detailed Analysis of Remedial Alternatives 6-1
6.1 Introduction 6-1
6.2 Threshold Criteria 6-2
6.2.1 Overall Protection of Human Health and the Environment 6-2
6.2.2 Compliance with Applicable or Relevant and Appropriate
Requirements 6-3
6.3 Balancing Criteria 6-3
6.3.1 Long-Term Effectiveness and Permanence 6-3
6.3.2 Reduction of Toxicity, Mobility, or Volume through Treatment 6-4
6.3.3 Short-Term Effectiveness 6-5
6.3.4 Implementability 6-6
6.3.5 Cost 6-7
6.4 Detailed Analysis of Alternatives 6-7
6.4.1 Alternative 1 - No Action 6-8
6.4.2 Alternative 2 - Institutional Controls with Monitored Natural Recovery...6-9
6.4.3 Alternative 3 - Small Cap with Monitored Natural Recovery and
Institutional Controls 6-15
6.4.4 Alternative 4 - Containment with Monitored Natural Recovery
and Institutional Controls 6-18
6.5 Comparative Analysis of Alternatives 6-23
6.5.1 Overall Protection of Human Health and the Environment 6-24
6.5.2 Compliance with Applicable or Relevant and Appropriate
Requirements 6-24
6.5.3 Long-Term Effectiveness and Permanence 6-25
6.5.4 Reduction of Toxicity, Mobility, or Volume through Treatment 6-25
6.5.5 Short-Term Effectiveness 6-26
6.5.6 Implementability 6-26
6.5.7 Cost 6-27
Attachment 1: Remedial Alternatives Cost Estimates Table
7.0 References 7-1
in
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TABLE OF CONTENTS FEASIBILITY STUDY MAY09
Section Page
Tables
1-1 Surface Contamination Area of DDTs and PCBs 1-20
1-2 Sediment Physical Characteristics 1-35
2-1 Trend in White Croaker Contaminant Concentrations 2-21
2-2 Comparison of Total DDTs and PCBs in Pelagic Forage Fish 2-23
2-3 Summary of Box Model Parameters and Results 2-36
3-1 Recommended Screening Values for Recreational Fishers 3-2
3-2 Protectiveness Levels based on local fish consumption rates 3-3
3-3 EPA Ambient Water Quality Criteria 3-6
3-4 Relationship of COCs in White Croaker to Sediment 3-11
3-5 Summary of Potential Remediation Goals 3-12
5-1 Fill Volumes for Sediment Caps 5-18
5-2 Chemical and Physical Data for Potential Caps 5-19
5-3 Potential Cap Source Material 5-24
6-1 Overall Protection of Human Health and the Environment 6-2
6-2 Compliance with Applicable or Relevant and Appropriate Requirements 6-3
6-3 Long-Term Effectiveness and Permanence 6-4
6-4 Reduction of Toxicity, Mobility, or Volume through Treatment 6-4
6-5 Short-Term Effectiveness 6-5
6-6 Implementability 6-6
6-7 Comparison of Remedial Alternative Costs 6-28
6-8 Evaluation of Alternatives against CERCLA criteria 6-29
Figures
1-1 Site Location 1-3
1-2 Net Water Movement in the Southern California Bight 1-5
1-3 LACSD Outfalls Schematic 1-9
1-4 LACSD Sediment Sampling Locations 1-13
1-5 Surface Sediment Contours of DDTs -1992 1-15
1-6 Surface Sediment Contours of PCBs -1992 1-17
1-7 Concentrations of DDTs - USGS1992 Sediment Cores 1-19
1-8 Surface Sediment Contours of DDTs - 2002/2004 Average 1-23
1-9 Surface Sediment Contours of PCBs - 2002/2004 Average 1-25
1-10 DDE Concentrations - LACSD 2001 Sediment Cores 1-27
1-11 Concentrations of PCBs - USGS 1992 Sediment Cores 1-29
1-12 Ocean Monitoring Sites 1-33
IV
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TABLE OF CONTENTS FEASIBILITY STUDY MAY09
Section Page
Figures
2-1 Fish Sampling Locations 2-7
2-2 Ocean Fish Survey Sampling Locations 2-11
2-3 Comparison of PCBs/DDTs results in white croaker 2-17
2-4 White Croaker Sampling Locations for 2005 2-19
2-5 LACSD Stations along 60 m isobath 2-27
2-6 Examples of PV Shelf diversity 2-29
2-7 Biological organisms on Palos Verdes Shelf 2-31
2-8 DDE Trend at Station 3C 2-37
2-9 DDE Trend at Station 6C 2-39
2-10 Peak DDE in Cores along 60 m isobath 2-41
5-1 White Croaker Catch Ban Area 5-5
5-2 Grid CeU 8C 5-11
5-4 Sediment Cores Trend at Station 8C 5-13
5-5 Alternative 4 Capping Locations 5-21
Appendices
A Response to Palos Verdes Shelf Technical Information Exchange Group Comments
on the December 2008 Draft Feasibility Study
B Predictive Modeling of Natural Recovery
NRDA Expert Report: Predictive Modeling of the Natural Recovery of the
Contaminated Effluent-Affected Sediment, Palos Verdes Margin, Southern
California 1994
1996 Supplement to the NRDA Expert Report
Forecasting Water Quality on the Palos Verdes Shelf (Draft), Nov. 2008
C Food Web Models
Technical Memorandum: Development of a Relationship Between Fish Tissue
and Sediment Contaminant Concentrations, 2009
Technical Memorandum for Palos Verdes Shelf Superfund Site: Human Health
Risk Evaluation, 2006
D Institutional Controls Program Implementation Plan (Draft), January 2009
E Options for In Situ Capping of Palos Verdes Shelf Contaminated Sediments, 1999
F Development and Analysis of Removal Alternative, Palos Verdes Shelf, 2008
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Acronyms and Abbreviations
°c
Hg/cm2/yr
ARAR
ASTM
AWQC
Bight '94
BMP
CAD
CCR
CDF
CDFG
CERCLA
CFR
CGS
cm
cm/ sec
cm/ year
cm2
CO2
CSMW
CST
CTE
CZMA
DBW
Celsius
micrograms per square centimeter per year
micrograms per kilogram
micrograms per liter
micrometer(s)
applicable or relevant and appropriate requirement
American Society for Testing and Materials
ambient water quality criteria
1994 Southern California Bight Pilot Project
best management practice
contained aquatic disposal
California Code of Regulations
confined disposal facility
California Department of Fish and Game
Comprehensive Environmental Response, Compensation, and
Liability Act of 1980
Code of Federal Regulations
California Geological Survey
centimeter(s)
centimeters per second
centimeters per year
square centimeter(s)
carbon dioxide
California Coastal Sediment Management Workgroup
Los Angeles Contaminated Sediment Long-Term Management
Strategy
central tendency exposure
Coastal Zone Management Act
California Department of Boating and Waterways
ES042007001SCO/DRD2260.DOC/071310003
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ACRONYMS AND ABBREVIATIONS
DDD
DDE
DDMU
DDNU
DDT
DDTs
DNAPL
EE/CA
Eh
EPA
ERA
ERDC
FCEC
FDA
Fe
FR
FS
g
g/day
g/L
gpm
GPS
GRA
HARS
H202
HHRE
HI
HQ
IRIS
JWPCP
kg
dichlorodiphenyldichloroethane
dichlorodiphenyldichloroethene
l-chloro-2/2-bis (p-chlorophenyl) ethylene
unsym-bis (p-chlorophenyl) ethylene
dichlorodiphenyltrichloroethane
dichlorodiphenyltrichloroethane and its metabolites
dense nonaqueous phase liquid
Engineering Evaluation/Cost Analysis
redox potential
United States Environmental Protection Agency
ecological risk assessment
Engineering Research and Development Center
Fish Contamination Education Collaborative
Food and Drug Administration
iron
Federal Register
Feasibility Study
gram(s)
grams per day
grams per liter
gallons per minute
global positioning system
general response action
Historical Area Remediation Site
hydrogen sulfide
human health risk evaluation
hazard index
hazard quotient
Integrated Risk Information System
Joint Water Pollution Control Plant
kilogram(s)
ES042007001SCO/DRD2260.DOC/071310003
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ACRONYMS AND ABBREVIATIONS
km
km2
L
LACDHS
LACSD
Ibs
LC
LD
LOEC
LU
m
MDS
mg
mg/kg
mg/L
mgd
mi2
ml
mm
MMS
MNR
Montrose
MPRSA
MSRP
NAS
NCP
NEL
ng/L
NOAA
kilometer (s)
square kilometer(s)
liter(s)
Los Angeles County Department of Health Services
Los Angeles County Sanitation Districts
pound(s)
Landward Center
Landward Downstream
lowest observed effects concentration
Landward Upstream
meter(s)
square meter (s)
cubic meter(s)
Mud Dump Site
milligram(s)
milligrams per kilogram
milligrams per liter
million gallons per day
square mile(s)
milliliter(s)
millimeter(s)
United States Minerals Management Service
monitored natural recovery
Montrose Chemical Corporation of California
Marine Protection, Research, and Sanctuaries Act of 1972
Montrose Settlements Restoration Program
National Academy of Sciences
National Contingency Plan
Naval Electronic Laboratory
nanograms per liter
National Oceanic and Atmospheric Administration
ES042007001SCO/DRD2260.DOC/071310003
VII
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ACRONYMS AND ABBREVIATIONS
NOEC
NPDES
NPL
NPV
NRDA
OCHCA-EHD
O&M
OEHHA
OSWER
Pa
PCBs
ppm
ppt
PRA
PV Shelf
RAO
RCRA
redox
RI
RME
ROD
SAB
SAIC
SCB
SD
SEC
SMP
SPI
SPMD
SU
SWRCB
no observed effects concentration
National Pollutant Discharge Elimination System
National Priorities List
net present value
Natural Resource Damage Assessment
Orange County Health Care Agency - Environmental Health Division
operations and maintenance
Office of Environmental Health Hazard Assessment
Office of Solid Waste and Emergency Response
pascal(s)
polychlorinated biphenyls
parts per million
parts per trillion
Priority Remediation Area
Palos Verdes Shelf
remedial action objective
Resource Conservation and Recovery Act of 1976
reduction-oxidation
Remedial Investigation
reasonable maximum exposure
Record of Decision
species diversity, abundance, biomass
Science Applications International Corporation
Southern California Bight
Seaward Downstream
sediment effect concentration
Sediment Master Plan
sediment-profile image/imagery
semipermeable membrane device
Seaward Upstream
State Water Resources Control Board
ES042007001SCO/DRD2260.DOC/071310003
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ACRONYMS AND ABBREVIATIONS
TABS
TBC
TCLP
TOC
TSS
TTLC
U.S.
U.S.C.
UCL
USAGE
USGS
WES
tetrapropylene-based alkylbenzene isomer
to be considered
toxicity characteristic leaching procedure
total organic carbon
total suspended solids
total threshold limit concentration
United States
United States Code
upper confidence level
United States Army Corps of Engineers
United States Geological Survey
Waterways Experiment Station
cubic yard(s)
ES042007001SCO/DRD2260.DOC/071310003
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Executive Summary
The Palos Verdes Shelf Superfund site (PV Shelf) is a large area of contaminated sediment
on the continental shelf and slope off the coast of Los Angeles, California. PV Shelf is
Operable Unit 5 of the Montrose Chemical Superfund site. At one time, the Montrose
Chemical Corporation of California, Inc. (Montrose) operated the nation's largest
manufacturing plant of the pesticide, dichlorodiphenyltrichloroethane (DDT). Montrose
dismantled its Los Angeles County plant in 1983. However, waste-related contamination at
the former plant site led to its placement on the National Priorities List of hazardous sites
(i.e., Superfund) in 1989. The former plant property is now the core of the Montrose
Chemical Superfund site in Torrance, California. Wastes from the manufacturing plant
contaminated soil and groundwater in the vicinity of the former plant property as well as
the waters and sediment within the Port of Los Angeles and in the ocean, on the PV Shelf.
The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)
response activities on the PV Shelf are part of the response activities being conducted by
EPA in connection with the Montrose Chemical Superfund Site.
Waste from Montrose reached PV Shelf via the Los Angeles County sanitation system.
Since 1937, the main wastewater treatment plant of the Sanitation Districts of Los Angeles
County (LACSD) has sent treated industrial and municipal wastewater (effluent) to ocean
outfalls at White Point on the Palos Verdes Peninsula. From the 1950s to 1971, Montrose
released tons of DDT and associated waste into the sewer system to be discharged
ultimately from the outfalls at White Point. Other industries, notably Westinghouse,
Simpson Paper Company, and Potlatch Corporation, discharged chemical compounds used
as coolants and lubricants, called polychlorinated biphenyls (PCBs), into the Los Angeles
sewer system as well. Peak mass emissions of effluent solids from the outfalls occurred in
1971. Since 1971, the heavily contaminated sediment has been gradually buried by less
contaminated effluent and natural sediment. This has created a layer of cleaner sediment on
top of the DDT- and PCB-contaminated sediment.
Purpose and Scope
This Feasibility Study (FS) describes the development, evaluation, and comparison of
remedial action alternatives to manage the contaminated sediment at the PV Shelf site.
Remedial action alternatives that ensure the protection of human health and the
environment may involve reductions in concentrations of contaminants to health-based
levels, prevention of exposure to contamination through engineering or institutional
controls, or some combination of these activities depending on the site-specific conditions
(EPA, 1988a). The purpose of the FS is to develop and evaluate a range of remedial
alternatives that are appropriate to site-specific conditions, protective of human health and
the environment, and comply with CERCLA. This FS has been prepared in accordance with
the EPA documents Interim Final Guidance for Conducting Remedial Investigations and
Feasibility Studies under CERCLA (EPA, 1988a) and Contaminated Sediment Remediation
Guidance for Hazardous Waste Sites (EPA, 2005).
PVSHELF_FS ES2/ MAY09 ES-1
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EXECUTIVE SUMMARY
In keeping with the recommendations of the Contaminated Sediment Remediation Guidance,
EPA has decided to recommend an interim remedial action. While carrying out the interim
action, EPA will conduct additional investigations and pilot studies that will contribute to
the design of a Superfund remedy for PV Shelf that reduces risk and provides a permanent
solution to the maximum extent possible.
Site Description
The California coast from Pt. Conception to the Mexican border curves inward, forming a
large bay called the "Southern California Bight." The Palos Verdes Peninsula is a small but
prominent land mass extending into the Southern California Bight. It is bordered by Santa
Monica Bay to the north and the San Pedro Shelf to the south. The Channel Islands lie to the
west and northwest. The narrow underwater shelf off the Palos Verdes Peninsula is called
the Palos Verdes Shelf. The shelf is about 1.5 to 4 kilometers (km) wide, up to 25 km long,
and has a slope of 1 to 3 degrees. Kelp beds and rocky patches are found in shallower
waters near shore; however, most of the shelf is covered by thick sediment. A shelf break
(i.e., a zone of transition from the relatively flat shelf to the steeper continental slope) occurs
at water depths of 70 to 100 meters (m). The continental slope drops seaward from the shelf,
with a width of approximately 3 km and an average slope of 13 degrees, to a depth of
approximately 800 m (Lee, 1994).
The FS defines the PV Shelf Study Area as the area of the shelf and slope off the Palos Verdes
Peninsula between Point Fermin and Redondo Canyon, from the shore to the 200-m isobath
(depth contour). This is the study area used in the ecological risk assessment and represents
a recognizable geographic area. It includes the deposit of highly contaminated sediment and
the area around it. An estimated 5.7 million tons of sediment have been affected by the
effluent discharged from the White Point outfalls. Mixed within this effluent-affected
sediment are an estimated 110 tons of DDT and 10 tons of PCBs.
The effluent-affected sediment forms an identifiable deposit over a mile offshore at a depth
of 50 m to the shelf break. The deposit ranges in thickness from 5 centimeters (cm) to over 60
cm. A moderately contaminated surface layer of sediment covers a buried layer of highly
contaminated material deposited before 1980. DDT concentrations in the buried deposit
exceed 200 mg/kg, while PCBs in the buried deposit reach 20 mg/kg. For most of the
deposit, these maximum concentrations are found under about 30 cm of cleaner sediment.
The exception is the area near the outfalls, where surface concentrations of DDT can be as
high as 200 mg/kg. The deposit is thickest and has the highest concentrations of DDTs and
PCBs along the 60-m isobath. The slope has the second highest contaminant concentrations
in surface sediment; however, the deposit is thin.
The area of PV Shelf with surface concentrations exceeding 1 mg/kg DDT is approximately
15 square miles. The area with surface concentrations exceeding 1 mg/kg PCBs is about 2.4
square miles. Although contaminant concentrations have dropped from historical highs,
concentrations of DDT and PCBs in fish continue to pose a threat to human health and the
natural environment.
ES-2
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EXECUTIVE SUMMARY
Risk Summary
The PV Shelf sediment is too deep for direct human contact; however, fish residing on PV
Shelf accumulate concentrations of DDTs and PCBs that are potentially harmful to humans
and wildlife. EPA's updated human health risk evaluation, contained in Appendix C,
assessed two seafood consumptions scenarios: a reasonable maximum exposure (RME) for
people who consume fish several times a week, and a central tendency exposure (CTE) that
represents a meal a week. Under the RME scenario, all six species of fish analyzed contained
levels of DDTs and PCBs that posed a potential health risk. The health also extends to
wildlife. Concentrations of DDTs and PCBs in fish are above protectiveness levels
recommended for piscivorous wildlife.
DDTs and PCBs are the contaminants of concern (COCs) at the site. COCs in sediment are
the source of contamination to surface water and biota. Once remedial actions to remove,
treat, or contain the COCs in the sediment deposit are taken, reduction of in surface water
and fish will occur naturally.
Applicable or Relevant and Appropriate Requirements
As discussed above, EPA will recommend an interim remedy to begin remediation of the
PV Shelf site. Any action taken by EPA must comply with existing laws and regulations.
During the development of remedial alternatives, applicable or relevant and appropriate
requirements (ARARs) are identified. ARARs generally are classified into the following
three categories: chemical-specific, location-specific, and action-specific requirements.
Remedial Action Objectives
Many fishes found on PV Shelf are unsuitable for human consumption because of their
levels of DDTs and PCBs. Wildlife that consume fish or fish-eating animals are potentially
at risk as well. The Food and Drug Administration (FDA) has set action limits or tolerance
levels for contaminants in fish fillets: 5 mg/kg DDT and 2 mg/kg PCBs. However, these
are not risk-based levels. The PV Shelf Remedial Investigation Report included risk
assessments that used PV Shelf-specific data to calculate exposures that would fall within
EPA's acceptable risk range.
Based on CERCLA and the National Contingency Plan (NCP), the remedial action objectives
(RAOs) established for the PV Shelf Study Area and their associated quantifiable
remediation goals are as follows:
• Reduce to acceptable levels the risks to human health from ingestion of fish exposed to
DDTs and PCBs.
• Achieve interim goals of 400 Mg/kg DDT and 70 Mg/kg PCBs in white croaker. These
concentrations provide levels of protection of 1 x 10'4 excess lifetime cancer risk for
anglers under the reasonable maximum exposure scenario (i.e., 116 g/day) and of 1 x
10'5 excess lifetime cancer risk for the central tendency exposure (21.4 g/day),
representative of recreational anglers.
/PVSHELF_FS ES2/ MAY09 ES-3
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EXECUTIVE SUMMARY
• Achieve median sediment concentration of 230 (j,g/kg DDTs at 1 percent Total
Organic Carbon (TOC) and 70 (ag/kg PCBs at 1 percent TOC.
• Maintain institutional controls program that aims to prevent contaminated fish from
reaching markets and educates anglers on safe fishing practices.
• Reduce concentrations of DDTs and PCBs in the surface waters over the PV Shelf to
meet ambient water quality criteria (AWQC) for protection of human health and
ecological receptors.
• Achieve AWQC for protection of human health (i.e., 0.22 ng/L DDT and 0.064 ng/L
PCBs). These criteria are more stringent than those for ecological receptors;
therefore, achieving these goals will protect wildlife as well.
• Minimize potential adverse impacts to sensitive habitats and biological communities on
the PV Shelf during remedial implementation.
• Before implementation of any remedy, prepare a monitoring program to assure the
kelp beds on PV Shelf are protected.
• Use low-impact techniques and best management practices, e.g., plan field work for
season when tides and currents are less energetic, set not-to-exceed surge speeds for
dredging or capping, monitor sediment resuspension, contaminants in water
column, and stop action if monitoring plan standards are exceeded.
The goal of the FS is to develop and evaluate remedial alternatives that achieve these RAOs.
Remedial Action Alternatives
Section 4.0 of the Feasibility Study identifies general response actions (GRAs) used to
develop remedial action alternatives. Response actions typically applied to sediment sites
are containment, removal, or monitored natural recovery. These three response actions
along with their applicable technology types and process options were assessed in detail.
Technical assessments of natural recovery, containment (capping) and removal (dredging)
are contained in Appendices B, E and F. The remedial technologies are used to construct
alternatives, and these alternatives are then screened for effectiveness, implementability,
and relative cost. During analysis of response actions, it became clear that additional studies
would be necessary to design the most effective remedy and that an iterative or phased
approach to remediating PV Shelf was appropriate.
EPA will issue an interim ROD. The interim ROD will call for studies that will help
formulate the final ROD. The FS developed five alternatives; however, the removal
alternative was screened out as technically impracticable. The following four remedial
action alternatives are selected for detailed analysis.
Alternative 1 — No Action. The no action alternative serves as a baseline against which
other options are compared. The National Contingency Plan (NCP) requires consideration
of the no action alternative in order to determine the risks to public health and the
environment if no actions were taken.
ES-4
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EXECUTIVE SUMMARY
Alternative 2—Institutional Controls and Monitored Natural Recovery. This alternative
monitors reductions in contaminants in the PV Shelf Study Area while reducing risks to
human health associated with the consumption of fish that contain DDTs and PCBs through
nonengineered controls. Alternative 2 is designed to limit consumption of contaminated
fish through an extensive institutional controls (ICs) program while monitoring the
naturally occurring reductions of COCs in sediment, water and fish.
Data collected from the PV Shelf Study Area indicate natural processes such as chemical
transformation of DDE, contaminant loss through transport, and sediment burial are
reducing contaminant levels in sediment, water, and fish. This alternative would monitor
the migration and degradation of contaminants and the impact of contaminants on
ecological receptors at the PV Shelf. Until contaminant concentrations drop to RAO levels,
this alternative would keep in place the institutional controls (ICs) program. The ICs
program limits human consumption of potentially contaminated fish by educating the
public on safe fishing practices, supporting state commercial fishing ban and fish advisories,
and monitoring fish contamination levels from ocean to market.
The cost of Alternative 2 is estimated to be $15.5 million dollars over 10 years. Table ES-1
details the elements of this alternative.
Alternative 3—Institutional Controls, Monitored Natural Recovery and Small Cap. This
alternative includes the ICs and MNR program elements of Alternative 2; however, it would
enhance natural recovery by placing clean silty sand over an area of PV Shelf that appears to
be eroding and where the highest surficial contaminant concentrations are found. The small
cap would accelerate natural recovery through:
• Physical armoring of the bottom boundary layer (mudline) from erosion caused by
waves and currents
• Chemical isolation of contaminants from the water column to reduce molecular
diffusion of dissolved contaminants into the water column
• Reduction of exposure and uptake of contaminants by benthic organisms by replacing
effluent-affected sediment with a clean layer for recolonization by sediment-dwelling
invertebrates.
Enhanced monitored natural recovery would use low-impact techniques to place a 45-cm
layer over approximately 1.3 km2 (320 acres). Treatability studies to verify effectiveness of
low-impact engineering techniques, and to characterize thoroughly the target area would
precede construction. The ICs program would continue until contaminant concentrations in
fish reach remediation goals.
The cost of Alternative 3 is estimated to be $49 million dollars over 10 years. Table ES-1
details the elements of this alternative.
Alternative 4 — Containment with Monitored Natural Recovery and Institutional Controls.
This alternative consists of placing a sand cap over contaminated effluent-affected sediment
at the PV Shelf Study Area, implementing institutional controls, and monitoring natural
recovery processes. This alternative is designed to limit the uptake of contaminants of
concern by marine organisms and ultimately reduce the contaminant concentration in fish
/PVSHELF_FS ES2/ MAY09 ES-5
-------
EXECUTIVE SUMMARY
within the PV Shelf Study Area. The objectives of placing a cap at the PV Shelf Study Area
are:
• Physical isolation of the effluent-affected sediment from the benthic environment to
reduce exposure and uptake of contaminants by organisms
• Physical armoring of the bottom boundary layer (mudline) from erosion caused by
waves and currents
• Chemical isolation of contaminants from the water column to reduce molecular
diffusion of dissolved contaminants into the water column.
Alternative 4 would place a 45-cm cap over 2.74 k m2 (approximately 680 acres) where the
effluent-affected deposit is thickest and has the highest contaminant concentrations at
depth.
The cost of Alternative 4 is estimated to be $76.7 million dollars over 10 years. Table ES-1
details the elements of this alternative.
Remedial Alternative Evaluation
The alternatives are evaluated in detail on the basis of the two threshold and five primary
balancing criteria specified in the Interim Final Guidance for Conducting Remedial Investigations
and Feasibility Studies Under CERCLA (EPA, 1988a); these criteria are:
• Overall protectiveness of human health and the environment
• Compliance with ARARs
• Long-term effectiveness
• Reduction of toxicity, mobility, or volume through treatment
• Short-term effectiveness
• Implementability
• Cost
In Section 6.0, alternatives are evaluated individually and comparatively against each
criterion. Table 6-8 shows how each alternative fares against the selection criteria. A
Proposed Plan describing EPA's preferred alternative will be developed and distributed for
public comment. The final two criteria — state acceptance and community acceptance—will
be evaluated following analysis of public comment on the proposed plan. After assessing
public comment, EPA will prepare an interim Record of Decision (ROD) detailing the
selected remedy.
ES-6
-------
Table ES-1: Description of Alternatives, Estimated Cost by Element
(Totals do not equal sums because of rounding, contingencies, project management costs)
Alternative 1: No Action Alternative
Program
NA
Cost
NA
Element
NA
No cost associated with this alternative
Details
NA
Timeframe
NA
Alternative 2: Institutional Controls and Monitored Natural Recovery Summary
Program
Cost
Element
Details
Timeframe
Institutional Controls Program
Community
Outreach and
Education
Angler outreach
Enforcement
and Monitoring
$880,000
$120,000
$58,000
$180,000
General
population
High-risk
population
Fish markets
fishing piers and
bait shops
pier-caught
white croaker
Commercial fish
markets; white
croaker analysis
Work with CBOs, media, and community relations specialists
to inform people about behaviors that reduce risk of eating
contaminated fish. Partner with health fairs, community fairs
and local health depts. to provide educational materials and
training; includes feedback to gauge behavior change; materials
in multiple languages
Specific outreach materials and messages focused on fish
preparation to reduce COCs, for ethnic groups who include fish,
particularly white croaker, as important part of their diet, and
women of child-bearing age
Outreach to commercial fish market owners to inform them
about dangers of buying fish from unlicensed dealers;
coordinated with market enforcement element.
Visit 8 fishing locations, 4-hr sessions at 4 times a week.
Educate anglers about fish contamination, fish advisories, ID of
contaminated fish species, and safer fish consumption
practices. Keep bait shops supplied with educational materials.
Every year collect 10 white croaker from four fishing locations
to analyze for DDTs and PCBs
Long Beach, LA and Orange counties Env. Health Dept.
market inspections. Estimate 250 market visits per year to 55
different markets; Check documentation of white croaker found
in markets, purchase fish and analyze for DDTs and PCBs
Ongoing
Ongoing
Ongoing
Ongoing
Annual
250 market visits
per year to approx.
55 markets
PVSHELF_FS ES2/ MAY09
ES-7
-------
EXECUTIVE SUMMARY
Alternative 2: Institutional Controls and Monitored Natural Recovery Summary
Program
Cost
$128,000
$33,000
Element
Wholesalers/
distributors
Collect fish from
catch ban area
Commercial
catch ban, sport
bag limit
Details
Local Env. Health Depts. — check wholesaler/ distributor
documentation; Work with CDFG/local depts. to develop
inspection plan for random sampling of white croaker for
analysis
Catch ban area monitoring: 5 areas, 10 white croaker and 10
kelp bass
CDFG patrols and enforcement; patrol catch ban area
Timeframe
Ongoing, look for
opportunities to
expand program
Every 5 years
Monthly patrols
Monitored Natural Recovery Program
Natural
Recovery
Monitoring
$100,600
+ 30,000 for
recovery
plan
$1,100,000
$274,000
Fish in ocean
monitoring
Sediment
sampling
Pore water and
water column
sampling
Sample fish from southeast and northwest of White Pt. outfalls
Collect 30 fish each of two species: 1 benthic feeding & 1
pelagic, for example:
• white croaker, barred sand bass or CA scorpionfish; and
• Pacific sardine or California chub mackerel
Analyze fish for DDTs & PCBs; analyze fillet and whole body
Use LACSD sampling grid stations 1 through 10, B thru D.
take duplicates at C & B stations for total of 50 cores; analyze
4-cm intervals for grain size, TOG, DDT (6 isomers, DDMU,
DDNU or DBF) and PCB congeners
Use passive samplers at same 30 stations at 3 m above seabed,
mid-column and 5 m below water surface. Deploy 3 samplers at
each location. Analyze for DDT (6 isomers) and PCBs
(congeners)
Year 1 and at Year 5
and 10 for the Five-
Year Review
Year 1 baseline,
fewer stations for
Year 5 and 10 Five-
Year Reviews
Year 1 baseline,
fewer stations for
Year 5 and 10 Five-
Year Reviews
Total ICs
Total MNR
Alternative 2
Capital cost
$ 1,900,000
$ 1,750,000
$ 3,650,000
Net Present value (7% discount rate, 10 year horizon)
$10,600,000
$ 1,250,000
Total
$12,500,000
$ 3,000,000
$11,850,000
Grand Total
$15,500,000
ES-8
PVSHELF_FS ES2/MAY09
-------
EXECUTIVE SUMMARY
Alternative 3: Institutional Controls and Enhanced Monitored Natural Recovery Summary
Program
Cost
Element
Details
Timeframe
Institutional Controls Program
Community
Outreach and
Education
Angler outreach
Enforcement
and Monitoring
$880,000
$120,000
$58,000
$180,000
$128,000
$33,000
General
population
High-risk
population
Fish markets
fishing piers and
bait shops
pier-caught
white croaker
Commercial fish
markets; white
croaker analysis
Wholesalers/
distributors
Collect fish from
catch ban area
Commercial
catch ban, sport
bag limit
Work with CBOs, media, and community relations specialists
to inform people about behaviors that reduce risk of eating
contaminated fish. Partner with health fairs, community fairs
and local health depts. to provide educational materials and
training; includes feedback to gauge behavior change; materials
in multiple languages
Specific outreach materials and messages focused on fish
preparation to reduce COCs, for ethnic groups who include fish,
particularly white croaker, as important part of their diet, and
women of child-bearing age
Outreach to commercial fish market owners to inform them
about dangers of buying fish from unlicensed dealers;
coordinated with market enforcement element.
Visit 8 fishing locations, 4-hr sessions at 4 times a week.
Educate anglers about fish contamination, fish advisories, ID of
contaminated fish species, and safer fish consumption
practices. Keep bait shops supplied with educational materials.
Every year collect 10 white croaker from four fishing location to
analyze for DDTs and PCBs
Long Beach, LA and Orange counties Env. Health Dept.
market inspections. Estimate 250 market visits per year to 55
different markets; Check documentation of white croaker found
in markets, purchase fish and analyze for DDTs and PCBs
Local Env. Health Depts. — check wholesaler/ distributor
documentation; Work with CDFG/local depts. to develop
inspection plan for random sampling of white croaker for
analysis
Catch ban area monitoring: 5 areas, 10 white croaker and 10
kelp bass
CDFG patrols and enforcement; patrol catch ban area
Ongoing
Ongoing
Ongoing
Ongoing
Annual
250 market visits
per year to approx.
55 markets
Ongoing, look for
opportunities to
expand program
Every 5 years
Monthly patrols
/PVSHELF_FS ES2/ MAY09
ES-9
-------
EXECUTIVE SUMMARY
Alternative 3: Institutional Controls and Enhanced Monitored Natural Recovery Summary
Program
Cost
Element
Details
Timeframe
Natural Recovery Monitoring Program
Natural
Recovery
Monitoring
$100,600
+ 30,000 for
recovery
plan
$1,100,000
$274,000
Fish in ocean
monitoring
Sediment
sampling
Pore water and
water column
sampling
Sample fish from southeast and northwest of White Pt. outfalls
Collect 30 fish each of two species: 1 benthic feeding & 1
pelagic, for example:
• white croaker, barred sand bass or CA scorpionfish; and
• Pacific sardine or California chub mackerel
Analyze fish for DDTs & PCBs analyze fillet and whole body
Use LACSD sampling grid stations 1 through 10, B thru D.
take duplicates at C & B stations; analyze 4 cm intervals
analyze for grain size, TOG, DDT (6 isomers, DDMU, DDNU or
DBF) and PCB congeners
Use passive samplers at same 30 stations at 3 m above seabed,
mid-column and 5 m below water surface. Deploy 3 samplers at
each location. Analyze for DDT (6 isomers) and PCBs
(congeners)
Year 1 & Year 5 and
10 for Five-Year
Review
Year 1 baseline,
fewer stations for
Year 5 and 10 Five-
Year Reviews
Year 1 baseline,
fewer stations for
Five-Year Review
Enhancement (sand/silt cover) Program
Sand/silt
Amendment
Total ICs
Total MNR
Total cover
Alternative 3
$6,000,000
$25,050,000
$1,900,000
$1,800,000
Capital cost
$ 1,900,000
$ 1,750,000
$32,950,000
$36,600,000
Treatability
Studies
Construction
Construction
Monitoring
O&M
Monitoring
define area to cover; characterize sediment, pilot low-impact
techniques
placement of 45-cm cover over approx. 320 acres; requires
864,000 CY of coarse silt /fine to medium sand material
monitoring arrays to track resuspension plume and turbidity,
sediment and water column sampling
sediment and water column sampling to assess cover thickness
and movement and contaminant flux
Net Present value (7% discount rate, 10 year horizon)
$10,600,000
$ 1,250,000
$ 555,000 (Cap 5-Yr Review)
$12,405,000
Total
$12,500,000
$ 3,000,000
$33,500,000
Year 1 & 2
Year 4
At 1st Five-Year
Review
Grand Total
$49,000,000
ES-10
PVSHELF_FS ES2/MAY09
-------
EXECUTIVE SUMMARY
Alternative 4: Containment, Institutional Controls and Monitored Natural Recovery Summary
Program
Cost
Element
Details
Timeframe
Institutional Controls Program
Community
Outreach and
Education
Angler outreach
Enforcement
and Monitoring
$880,000
$120,000
$58,000
$180,000
$128,000
$33,000
General
population
High-risk
population
Fish markets
fishing piers and
bait shops
pier-caught
white croaker
Commercial fish
markets; white
croaker analysis
Wholesalers/
distributors
Collect fish from
catch ban area
Commercial
catch ban, sport
Work with CBOs, media, and community relations specialists
to inform people about behaviors that reduce risk of eating
contaminated fish. Partner with health fairs, community fairs
and local health depts. to provide educational materials and
training; includes feedback to gauge behavior change; materials
in multiple languages
Specific outreach materials and messages focused on fish
preparation to reduce COCs, for ethnic groups who include fish,
particularly white croaker, as important part of their diet, and
women of child-bearing age
Outreach to commercial fish market owners to inform them
about dangers of buying fish from unlicensed dealers;
coordinated with market enforcement element.
Visit 8 fishing locations, 4-hr sessions at 4 times a week.
Educate anglers about fish contamination, fish advisories, ID of
contaminated fish species, and safer fish consumption
practices. Keep bait shops supplied with educational materials.
Every year collect 10 white croaker from four fishing location to
analyze for DDTs and PCBs
Long Beach, LA and Orange counties Env. Health Dept.
market inspections. Estimate 250 market visits per year to 55
different markets; Check documentation of white croaker found
in markets, purchase fish and analyze for DDTs and PCBs
Local Env. Health Depts. — check wholesaler/ distributor
documentation; Work with CDFG/local depts. to develop
inspection plan for random sampling of white croaker for
analysis
Catch ban area monitoring: 5 areas, 10 white croaker and 10
kelp bass
CDFG patrols and enforcement; patrol catch ban area
Ongoing
Ongoing
Ongoing
Ongoing
Annual
250 market visits
per year to approx.
55 markets
Ongoing, look for
opportunities to
expand program
Every 5 years
Monthly patrols
/PVSHELF_FS ES2/ MAY09
ES-11
-------
EXECUTIVE SUMMARY
Alternative 4: Containment, Institutional Controls and Monitored Natural Recovery Summary
Program
Cost
Element
bag limit
Details
Timeframe
Monitored Natural Recovery Program
Natural
Recovery
Monitoring
$100,600
+ 30,000 for
recovery
plan
$1,100,000
$274,000
Fish in ocean
monitoring
Sediment
sampling
Pore water and
water column
sampling
Sample fish from southeast and northwest of White Pt. outfalls
Collect 30 fish each of two species: 1 benthic feeding & 1
pelagic, for example:
• white croaker, barred sand bass or CA scorpionfish; and
• Pacific sardine or California chub mackerel
Analyze fish for DDTs & PCBs; analyze fillet and whole body
Use LACSD sampling grid stations 1 through 10, B thru D.
take duplicates at C & B stations; analyze 4 cm intervals
analyze for grain size, TOG, DDT (6 isomers, DDMU, DDNU or
DBF) and PCB congeners
Use passive samplers at same 30 stations at 3 m above seabed,
mid-column and 5 m below water surface. Deploy 3 samplers at
each location. Analyze for DDT (6 isomers) and PCBs
(congeners)
Year 1 & Year 5 and
10 for Five-Year
Review
Year 1 baseline,
fewer stations for
Year 5 and 10 Five-
Year Reviews
Year 1 baseline,
fewer stations for
Year 5 and 10 Five-
Year Reviews
Capping Program
Sand/Sediment
capping
$6,000,000
$51,100,000
$3,300,000
$2,500,000
Treatability
Studies
Construction
Construction
Monitoring
O&M
Monitoring
define area to cover; characterize sediment, pilot low-impact
techniques
placement of 45-cm cover over approx. 680 acres; requires
1,776,000 CY of sand/sediment material; assume 1/3 of
placement using low-impact technique, 2/3 use spreading
technique
monitoring arrays to track resuspension plume and turbidity,
sediment and water column sampling
sediment and water column sampling to assess cover thickness,
movement and contaminant flux
Year 1 & 2
Year 4 - 5
during construction
At 1st Five-Year
Review
Total ICs
Total MNR
Total capping
Alternative 4
Capital cost
$ 1,900,000
$ 1,750,000
$60,450,000
$64,100,000
Net Present value (7% discount rate, 10 year horizon)
$10,600,000
$ 1,250,000
$ 750,000 (Cap 5-Yr Review)
Total
$12,500,000
$ 3,000,000
$61,200,000
$12,600,000
Grand Total
$76,700,000
ES-12
PVSHELF_FS ES2/MAY09
-------
1.0 Introduction
The first draft of the Palos Verdes Shelf (PV Shelf) Feasibility Study (FS) was prepared by
CH2M HILL for the United States Environmental Protection Agency (EPA) under
Work Assignment No. 282-RICO-09CA (EPA Contract No. 68-W-98-225). Subsequent drafts
were prepared by EPA.
The PV Shelf is located off the coast of the Palos Verdes Peninsula near Los Angeles, California.
Marine sediment on the PV Shelf have been contaminated with the pesticide
dichlorodiphenyltrichloroethane (DDT) and its metabolites (hereafter referred to collectively as
DDTs), lubricants, called polychlorinated biphenyls (PCBs), metals, and other contaminants.
These contaminants entered the Los Angeles County sewer system as industrial waste and, after
treatment at Los Angeles County Sanitation Districts (LACSD) Joint Water Pollution Control
Plant (JWPCP), were discharged in the effluent onto PV Shelf through submarine outfalls at
White Point (see Figure 1-1).
1.1 Purpose and Organization of the Report
This FS describes the development, evaluation, and comparison of remedial action alternatives
to manage the contaminated sediments at the PV Shelf. It has been prepared in accordance with
the EPA documents Interim Final Guidance for Conducting Remedial Investigations and Feasibility
Studies under CERCLA (USEPA, 1988a) and Contaminated Sediment Remediation Guidance for
Hazardous Waste Sites (USEPA, 2005). The appendices include the detailed analyses of the
technologies considered in development of the alternatives (i.e., dredging, capping, and natural
recovery), as well as the institutional controls program currently in place to control risk and the
food web models used in assessing risk.
This FS is organized as follows:
• Section 1.0 - Introduction: Describes the purpose and report organization and summarizes
the remedial investigation report.
• Section 2.0 - Risk Assessments and Predictive Modeling of Future Conditions:
Summarizes human health and ecological risk assessments prepared for the site and
predictive models of future condition of the site, and their use in quantifying future risk.
• Section 3.0 - Remedial Action Objectives and Development of Remediation Goals:
Presents the development of remedial action objectives (RAOs), and lists the applicable or
relevant and appropriate requirements (ARARs) and remediation goals (RGs) for the
alternatives under consideration in the FS.
• Section 4.0 - Identification of General Response Actions and Screening of Remedial
Technologies: Identifies general response actions and remedial technologies and screens
them as they pertain to site conditions and contaminated media.
• Section 5.0 - Development and Screening of Alternatives: Develops and describes the
remedial action alternatives and conducts preliminary screening.
MAY09PVS CHART 1.DOC/
-------
1.0 INTRODUCTION DRAFT DEC08
• Section 6.0 - Detailed Analysis of Remedial Alternatives: Provides a detailed analysis of
the remedial alternatives using EPA criteria.
• Section 7.0 - References: Lists the references used in preparing the FS.
1.2 Background Information
This section summarizes the site description, site history, nature and extent of contamination,
fate and transport, and baseline risk assessments associated with the PV Shelf.
1.2.1 Site Description
The PV Shelf is a narrow part of the continental shelf off the Palos Verdes Peninsula along the
coast of Southern California. North of PV Shelf is Santa Monica Bay and south, San Pedro Basin.
About 42 kilometers from PV Shelf is Catalina Island, the Channel Island nearest to PV Shelf.
The PV Shelf is about 1.5 to 4 kilometers (km) wide, up to 25 km long, and has a slope of 1 to
4 degrees. A shelf break (i.e., a zone of transition from the relatively flat shelf to the steeper
continental slope) occurs at water depths of 70 to 100 meters (m). The continental slope extends
seaward from the shelf, with a width of approximately 3 km and an average slope of 13 degrees,
to a depth of approximately 800 m (Lee, 1994). For the purposes of the remedial investigation
(RI) and FS, the PV Shelf Study Area is defined as the area of the shelf and slope between Point
Fermin and Redondo Canyon from the shore to the 200-m isobath, as shown in Figure 1-1. The
net ocean patterns surrounding PV Shelf are shown in Figure 1-2.
In general, the PV Shelf region is characterized by (1) hard-bottom (rocky) habitat, including
some kelp bed areas and associated invertebrate, fish, and algae communities, from shore to at
least 20 m of water depth; (2) soft-bottom habitat, including invertebrate and fish communities,
over most of the rest of the shelf and slope to a water depth of at least 600 m; and (3) pelagic or
water column zones, representing important habitat for fish, invertebrates, birds, and mammals
from near the sea floor to the water surface. The exception to this pattern is the hard-substrate,
artificial reef habitat represented by the White Point outfall pipes that extend primarily over
soft-bottom areas to a water depth of approximately 63 m, some hard-bottom areas scattered
along the shelf, and more extensive hard-bottom areas paralleling the shelf break.
The thickness of naturally occurring shelf sediment varies, ranging from 32 m on the
southeastern part of the shelf to less than 10 m near Point Vicente. A patchy, thin sediment
layer with areas of bare rock occurs at the shelf break. Similar bedrock outcrops also occur over
the seafloor to the east of the outfall and over the Redondo Shelf to the west (Lee, 1994). Less
than one meter of sediment covers the Redondo Shelf (Drake et al., 1994).
The Palos Verdes Peninsula lies within the Palos Verdes Fault Zone. This fault zone is one of
many fault zones in the Los Angeles Basin and adjoining offshore areas in the California
continental boundary. The Palos Verdes Fault is a major fault that crosses the peninsula,
approximately parallel to the coastline. U.S. Geological Survey research estimates total fault-
slip rate near the Palos Verdes Peninsula to be around 3 mm/year (USGS, 2004). No large
earthquakes have occurred in the recent past along the Palos Verdes Fault Zone, which strikes
generally southeast across the San Pedro Shelf and nearshore areas. However, it is estimated
that this fault could produce an earthquake as large as M 7 (USGS, 2004).
1-2 /MAY09PVS CHAPT1.DOC
-------
Santa Monica
Bay
LOS ANGELES
COUNTY
Palos Verdes Peninsula
Los Angeles
Harbor
Palos Verdes
Shelf Site
Southern
California Bight
Southern California
ES102006019SC0335398.RR.01 PVS_009.ai 12/06
FIGURE 1-1
Site Location
Palos Verdes Shelf
Remedial Investigation Report
CH2MHILL
-------
1.0 INTRODUCTION DRAFT DEC08
This page intentionally blank
1-4 /MAY09PVS CHAPT1.DOC
-------
Point
Conception
Santa Barbara
Point
Dume
Los Angeles
Pa/os Verdes
Peninsula
Palos Verdes
Shelf Study Area
Santa Barbara
Island
Santa Calalina
Island
San Clemente
Island
San
Diego
Scale in kilometers
Source: After Mickey, B.M., 1992, Progress in Oceanography, V30: 37-115.
ES042007001SC0335398.RR.01 PVS_0012a FS.ai 5/07
FIGURE 1-2
Net Water Movement
in the Southern California Bight
Palos Verdes Shelf Study Area
Feasibility Study
CH2IVIHILL
-------
1.0 INTRODUCTION DRAFT DEC08
This page intentionally blank
1-6 /MAY09PVS CHAPT1.DOC
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1.0 INTRODUCTION
1.2.2 Site History
1.2.2.1 Montrose Chemical Superfund Site
From 1947 until 1982, Montrose Chemical Corp. (Montrose) operated a DDT-manufacturing
plant on 13 acres at 20201 Normandie Avenue in Los Angeles County, California. Stauffer
Chemical Company was the landowner. The Montrose plant operated 24 hours a day, 7 days a
week, 365 days a year, except for occasional plant shutdowns. During its 35 years of operation,
Montrose produced approximately 800,000 tons of DDT.
When the plant first opened, it discharged DDT-contaminated wastewater from its production
operations to a city sewer line via a private pressure sewer line owned by Stauffer Chemical.
This connecting line periodically clogged, resulting in the discharge of Montrose DDT-
contaminated wastewater to the natural stormwater drainage. When EPA investigated the
natural stormwater drain in the 1990s, residual levels of DDT in the drainage immediately
downstream of the Montrose plant property were in excess of 8,000 parts per million (ppm).
The Normandie Avenue plant property itself was contaminated by Montrose operations.
Investigations directed by EPA beginning in 1985 found significant contamination (primarily
DDT and chlorobenzene) in the shallow and deep soil at the Montrose plant property,
groundwater beneath and downgradient from the Montrose plant property, soil adjacent to and
in the vicinity of the property, the sewer line adjacent to and downstream of the Montrose plant
property, and, as mentioned above, portions of the stormwater pathway leading from the
Montrose plant to the Consolidated Slip in Los Angeles Harbor. Groundwater at the Montrose
site is contaminated with monochlorobenzene and other contaminants across six
hydrostratigraphic units and to distances up to 1.3 miles from the former Montrose plant site.
Dense nonaqueous phase liquid (DNAPL) is present under the former plant property to great
depth and is serving as a continuous source of groundwater contamination.
The Montrose Chemical Superfund Site was included on the National Priorities List (NPL) of
federal sites (i.e., Superfund) on October 4,1989. There are six operable units at the Montrose
Chemical Superfund Site: operable unit (OU) 1 soils, OU-2 stormwater pathway, OU-3 ground
water, OU-4 residential area, OU-5 Palos Verdes Shelf, and OU-6, historical stormwater
pathway. These OUs cover contamination found in soil, groundwater, the residential area near
the former Montrose plant, marine sediment, and stormwater pathways.
1.2.2.2 Sewer Lines to Palos Verdes Shelf
The Joint Water Pollution Control Plant (JWPCP) operated by the Sanitation Districts of Los
Angeles County (LACSD) has discharged treated waste onto PV Shelf since 1937. The first
submarine outfall discharged offshore of White Point at a depth of 34 m. As Los Angeles grew,
so did demand on the JWPCP. New outfalls were added every ten years. Treated effluent was
discharged at White Point:
• From 1937 to 1958 - through a 60-inch-diameter, three-outlet diffuser at a depth of 34 m
• From 1947 to 1966 - through a 72-inch-diameter diffuser at a depth of 49 m
• Since 1957 - through a 90-inch-diameter, Y-shaped diffuser at a depth of 64 m
• Since 1967 - through a 120-inch-diameter, L-shaped diffuser at a depth of 58 m
Currently, the 120-inch- and 90-inch-diameter outfalls are the primary outfalls, discharging
treated effluent through diffusers approximately 1.5 miles offshore. The older, 60-inch-diameter
and 72-inch-diameter outfalls are not in use, but could be used for backup or emergency
operations. The four outfalls are shown in Figure 1-3.
/MAY09PVS CHART 1.DOC/
-------
1.0 INTRODUCTION DRAFT DEC08
From 1953 until 1971, Montrose discharged DDT-contaminated wastewater from its operations
at the Montrose plant to two sewers operated by LACSD. These sewers conveyed the
wastewater to the JWPCP, where it received primary treatment and was discharged through the
White Point outfalls located on the PV Shelf.
In the early 1970s, LACSD initiated an investigation to identify and eliminate discharge of DDTs
and PCBs into their sewer system. LACSD identified the Montrose plant as the only significant
source of DDT in sewer flows to the JWPCP. PCBs entered the LACSD sewer system from
several industrial sources in the Los Angeles area, most notably from the Westinghouse Electric
Corporation, which manufactured and repaired electrical equipment at its Los Angles County
plant; from a paper-manufacturing plant in Pomona owned by Potlatch Corporation; and from
Simpson Paper Company. Like DDT from the Montrose plant, PCBs from these plants were
sent to the JWPCP and, after treatment, were discharged from the White Point outfalls onto the
PV Shelf.
LACSD estimated that the discharge from the Montrose plant was contributing 654 pounds (Ibs)
of DDT per day to the LACSD system. In 1971, Montrose ceased discharging waste into the
county sewer system. LACSD conducted cleaning operations in the two sewer lines adjacent to
and downstream of the Montrose property. Sediments in the two sewer lines contained in
excess of 7,700 Ibs of DDT, according to LACSD estimates.
Despite these efforts by LACSD, significant quantities of DDT-contaminated sediment remained
in the sewer line. After the plant closure in 1983, under EPA order, Montrose removed
approximately 162,000 Ibs of sediment from the sewer line downstream from the plant. Sewer
sediment samples from this removal operation showed levels of DDT in the sediment at 490,000
milligram per kilogram (mg/kg) and chlorobenzene at 2,200 mg/kg.
1.2.3 Summary of Remedial Investigation Report
1.2.3.1 Discharges of DDTs and PCBs
The primary historical source of chemical contaminants on the PV Shelf is effluent discharged
through the White Point outfalls. Contaminants in the effluent included chlorinated
hydrocarbons (e.g., DDTs and PCBs) as well as trace metals (e.g., cadmium, copper, lead, zinc,
and other metals), and organic matter. The primary source of DDTs was wastewater from
Montrose, which was the nation's largest DDT manufacturer. Sources of PCBs included various
industries in the greater Los Angeles area. The peak annual mass emissions of effluent solids
(167,000 metric tons), DDT (21.1 metric tons), and PCBs (5.2 metric tons) occurred in 1971
(USEPA, 2000a). The total discharge of suspended solids from 1937 to 1995 has been estimated
at about 4.1 million metric tons (Lee et al, 2002). An estimated 800 to 1,200 metric tons of DDT
were discharged from the outfalls from the 1950s through 1971 (USDOJ, 2000).
Contaminant emissions decreased after 1971 due to the disconnection of Montrose from the
sewer system and improved treatment of the effluent prior to discharge. Since then, continuous
improvements in treatment have reduced the load of suspended solids and contaminants,
culminating in November 2002, when all of the wastewater discharged from the JWPCP started
receiving full secondary treatment. Discharge of suspended solids is now less than 8,000 metric
tons a year (mt/yr). The effluent concentrations of DDT have been near or below the detection
limit since 1989 and have not been detected since 2002. PCBs have not been detected above the
/MAY09PVS CHAPT1.DOC
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southern \ Area o
California Bight \hltereSt \San D/eio
Southern California
Note: The 120-inch- and 90-inch-diameter outfall are the primary outfalls.
Please refer to Section 1.2.3.1 for more information on the outfalls.
Source: Annual Report 2004 - Palos Verdes Ocean Monitoring, LACSD, 2005.
ES042007001SC0335398.RR.01 PVS_0011a FS.ai 5/07
FIGURE 1-3
LACSD Outfalls Schematic
Palos Verdes Shelf Study Area
Feasibility Study
CHZIVIHiLL
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1.0 INTRODUCTION DRAFT DEC08
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/MAY09PVS CHAPT1.DOC
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1.0 INTRODUCTION
detection limit since 1985 (LACSD, 2006). The reporting limits are currently 0.01 microgram per
liter (|ig/L) for the various isomers of DDT, and between 0.05 (J,g/L and 0.5 (J,g/L for the PCB
Arochlors (LACSD, 2007).
1.2.3.2 Nature and Extent of Contamination
Sediment from the outfalls combined with material from other sources (most notably, erosion
from the Portuguese Bend Landslide) formed an effluent-affected (EA) deposit on the PV Shelf
and slope. Studies in 1992 for the Natural Resource Damage Assessment (NRDA)(Lee et al.,
1994) indicated that a 5-centimeter (cm) to 60-cm-thick elliptical-shaped, EA deposit extended
over most of the shelf and slope from Point Fermin to Point Vicente. The EA deposit had an
estimated total volume of over 9 million cubic meters (m3) and covered more than 40 square
kilometers (km2). Of that total, 70 percent occurred on the shelf and 30 percent on the slope (Lee,
1994). The 1992 studies and biennial sediment monitoring conducted by LACSD showed that
almost the entire deposit was contaminated with DDTs and PCBs. The accumulated mass of
DDTs and PCBs remaining in sediment at the PV Shelf have been estimated at 100 metric tons
and 10 metric tons, respectively (EPA, 2001).
The shore side of the EA deposit ends relatively sharply at the 30-m depth contour, while the
ocean side extends over the PV Shelf break to the Mid- to Lower Slope (LACSD, 2005). Cross-
shore, the thickest part of the EA deposit extends along the 60-m isobath. Along-shore, the
deposit is thickest (60+ cm) near the 90-inch outfall. It thins rapidly toward the southeast, just
exceeding 15 cm a kilometer (km) from the outfall. It tapers much more gradually toward the
northwest. About 12 km northwest from the outfalls, the EAdeposit is still 25 cm thick. This
elliptical shape of the deposit is consistent with bi-directional dispersion from the outfall that has
been skewed upcoast in the direction of the long-term average current. On the northwest end,
the increased thickness of the EA deposit and lower contaminant concentrations also suggest
admixture of Portuguese Bend Landslide sediment.
Contaminant concentrations are lowest in the surface sediment (top 5-20 cm of the deposit) and
much higher in the older and more deeply buried layers of the deposit. Despite reductions in the
discharge of suspended solids, a large mass of effluent-affected sediment remains on the PV
Shelf and slope (LACSD, 2005). The sediments can be categorized into three layers:
• Native Sediments -Native sediment pre-dates the outfall construction. The native sediment
is coarser, has less organic material, and is less cohesive. It was supplied by local rivers and
by erosion of the coastline, including the Portuguese Bend Landslide. Generally, the EA
deposit lies on top of the native sediment; however, in waters less than 40 m deep, where
bottom wave activity is higher, sediments are generally sandy, and there is no obvious layer
of EA sediment on top of pre-effluent sediment. Some EA material may be worked into
surface sediment at these inshore regions; however, wave activity kept EA sediment from
accumulating. Native sediment is characterized by higher bulk densities and lower organic
carbon content (Eganhouse and Pontolillo, 2000).
• Heavily Contaminated Sediment - Above the native sediment exists a heavily
contaminated layer approximately 20 to 25 cm thick. These sediments have the highest
levels of contamination and slightly higher water content, consistent with more rapid
deposition when large amounts of highly contaminated sediment were discharged from the
outfalls. They are characterized by clay and silts, significantly elevated organic carbon
content, and low bulk densities. These sediments were deposited when discharges from the
/MAY09PVS CHART 1.DOC/
-------
1.0 INTRODUCTION DRAFT DEC08
outfalls contained high levels of suspended solids, DDTs, and PCBs (Eganhouse and
Pontolillo, 2000).
• Surficial Sediments - These sediments in the upper 15 to 20 cm are characterized by lower
concentrations of DDTs and PCBs, they are more uniform, and have higher bulk densities,
and slightly elevated organic carbon concentrations. The properties of the surface layer are
consistent with lower deposition rates of less contaminated material and physical reworking
by waves, currents and benthic invertebrates. This is the most biologically active layer of
sediment (Eganhouse and Pontolillo, 2000).
1.2.3.3 Historical Distribution of Mass of DDTs and PCBs: 1992 Data
Areal Extent of Contaminants
Under its National Pollutant Discharge Elimination System (NPDES) permit, LACSD is
required to monitor the health of the PV Shelf. As part of its monitoring program, LACSD
collects surficial sediment samples from 44 sampling stations and analyzes them for a number
of parameters, including DDTs and PCBs (Figure 1-4). LACSD's sampling grid consists of
11 transects from Redondo Canyon to Point Fermin, with sampling locations at 4 depths:
• 30 m (D Stations)
• 61 m (C stations)
• 152 m (B stations)
• 305 m (A stations)
LACSD samples collected in 1992 had surface concentrations of DDTs ranging from 0.2 milligram
per kilogram (mg/kg) at Station OD to 27.7 mg/kg at Station 8B, with the highest concentrations
of DDTs found near the Y-outfall (Stations 8B and 8C). Concentrations of DDTs exceeding
10 mg/kg covered approximately 8 km2, extending north from the 9 transect to the 4 transect,
encompassing the 60-m isobath and extending to the 200-m isobath (Figure 1-5). Concentrations
of DDTs exceeding 1 mg/kg covered approximately 44.5 km2, extending from the 10 transect to
north of the 1 transect, encompassing the 60-m isobath and extending to the 200-m isobath.
Please note that in addition to the 1992 LACSD data, Figure 1-5 uses four samples collected
during the 1994 Southern California Bight Pilot Project (Bight '94), one 1993 LACSD sample, and
two 1992 National Oceanic and Atmospheric Administration (NOAA) samples to provide
actual concentrations of DDTs between the 0 and 1 transects and north of the 0 transect.
Shoreline concentrations have been set at 0.05 mg/kg for contouring.
For PCBs, the highest concentrations were found at Stations 6B and 5B, northwest of the outfall,
followed by Stations 8B and 8C near the Y-outfall. Concentrations of PCBs exceeding 1 mg/kg
covered approximately 8.4 km2, extending from midway between the 8 and 9 transects east to
the 4 transect, and from approximately the 40-m isobath to the 200-m isobath (Figure 1-6).
Concentrations of PCBs exceeding 0.3 mg/kg covered approximately 22.5 km2, extending from
the 10 transect to north of the 1 transect, and from approximately the 40-m isobath to the 200-m
isobath. Please note that in addition to the 1992 LACSD data, Figure 1-6 uses two simulated
transects inserted between the 0 and 1 transects to approximate sediment concentrations where
no data exist. The simulated transects were set as an average of the 0 and 1 transect
concentrations. Shoreline concentrations have been set at 0.05 mg/kg for contouring.
1-12 /MAY09PVS CHAPT1.DOC
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PALOS VERGES
Source: Los Angeles County Sanitation District, 2006. Annual Report, 2005 Palos Verdes Ocean Monitoring, July.
ES042007001SC0335398.RR.01 PVS_0037 FS.ai 5/07
FIGURE 1-4
LACSD Sediment Sampling Locations
'a/os Verdes Shelf Study Area
Feasibility Study
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1.0 INTRODUCTION DRAFT DEC08
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1-14 ES042007001SCO/DEC08PVS CHART 1.DOC/071300006
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PALOS VERGES
PENINSULA
SURFACE SEDIMENT (0 - 2 CM)
CONTOURS OF DDTs, 0-200 M WATER
DEPTH (mg/kg DW)
X Sediment Sample Locations
— Outfalls
^| 0-0.05
^| 0.05 -0.1
~1 0.1 -0.2
Note: In addition to the 1992 LACSD data, this figure uses four Bight '94 samples, one 1993 LACSD sample, and two 1992 NOAA samples to provide actual
concentrations of DDTs between the 0 and 1 transects and north of the 0 transect. Shoreline concentrations have been set at 0.05 mg/kg for contouring.
ES042007001SC0335398.RR.01 PVS 0040b FS.ai 5/07
FIGURE 1-5
Surface Sediment Contours of DDTs -1992
Pa/os Vercfes Shelf Study Area
Feasibility Study
CH2MHILL
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1.0 INTRODUCTION DRAFT DEC08
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1-16 ES042007001SCO/DEC08PVS CHART 1.DOC/071300006
-------
PALOS VERDES
PENINSULA
SURFACE SEDIMENT (0 - 2 CM)
CONTOURS OF PCBs, 0-200 M WATER
DEPTH (mg/kg DW)
X Sediment Sample Locations
— Outfalls
•B 0 - 0.05
H 0.05 - 0.075
•• 0.075-0.1
I I 0.1-0.15
I I 0.15-0.2
I I 0.2 - 0.3
I I 0.3 - 0.5
I I 0.5 - 0.75
I I 0.75 -1
I 11 -1.25
H 1.25-1.5
••1.5-2
Note: In addition to the 1992 LACSD data, two simulated transects were inserted between the 0 and 1 transects to approximate sediment concentrations where no
data exist. The simulated transects were set as an average of the 0 and 1 transect concentrations. Shoreline concentrations have been set at 0.05 mg/kg for contouring.
ES042007001SC0335398.RR.01 PVS 0041bFS.ai 5/07
FIGURE 1-6
Surface Sediment Contours of PCBs -1992
Pa/os Verctes Shelf Study Area
Feasibility Study
CH2MHILL
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1.0 INTRODUCTION DRAFT DEC08
This page intentionally blank
1-18 ES042007001SCO/DEC08PVS CHART 1.DOC/071300006
-------
1.0 INTRODUCTION
As stated above, The Natural Resource Trustees performed a comprehensive evaluation of the
mass and distribution of contaminants within the PV Shelf Study Area in 1992 (Lee et al. 1994).
As part of these studies, the United States Geological Survey (USGS) collected sediment cores at
23 stations and analyzed them for DDTs (Figure 1-7). The average and maximum
concentrations of DDTs southeast of the outfalls were highest in the shallow or surface
sediment interval (0 to 15 cm). Northwest of the outfalls, the highest concentrations of DDTs
occurred in the 16- to 30-cm or 31- to 45-cm intervals. The highest concentrations of DDTs were
located in water depths of 50 to 60 m; the maximum concentration of DDTs (305 mg/kg) was
detected at Station 564 at a water depth of 56 m in the 16- to 30-m sediment depth interval.
1.2.4 Present Distribution of Mass of DDTs and PCBs: 2001 through 2005 Data
As mentioned above, LACSD takes surface sediment samples at 44 stations across the Shelf and
slope as part of its NPDES monitoring program. The current distribution of DDTs and PCBs in
the top 2 cm of sediment was developed using LACSD surface samples collected in 2002 and
2004. In addition, sediment cores collected by LACSD at sample stations located along the 61-m
isobath in 2001, 2003, and 2005 provide a view of the current sediment-contamination profile at
depth in the PV Shelf Study Area. The comparison of these new data sets to older data (primarily
the 1992 USGS cores and LACSD data) is presented as evidence of long-term changes in the
distribution and magnitude of sediment concentrations of DDTs and PCBs.
1.2.4.1 Areal Extent of Contaminants
Averaging the LACSD samples collected in 2002 and 2004, surface (0 to 2 cm) concentrations of
DDTs range from 0.159 mg/kg at Station 2D to 140.5 mg/kg at Station 8C, with the highest
concentrations of DDTs found near the Y-outfall (Stations 8B and 8C). Concentrations of DDTs
exceeding 10 mg/kg covered approximately 3.6 km2, primarily along the 61-m isobath and the
slope, from the outfalls to the 4 transect (Figure 1-8). Concentrations of DDTs exceeding 1
mg/kg covered approximately 39.1 km2, extending from the 9 transect to north of the 1 transect,
encompassing the 61-m isobath and extending down the slope. In addition to the 2002/2004
LACSD data, Figure 1-8 uses four Bight' 94 samples, one 1993 LACSD sample, and two 1992
NOAA samples to provide actual concentrations of DDTs between the 0 and 1 transects and
north of the 0 transect. Shoreline concentrations have been set at 0.05 mg/kg for contouring.
Concentrations of PCBs range from not detected at several stations to 3.19 mg/kg at station 7B,
on the slope. The highest concentrations of PCBs were located at station 7B, 8B, and 8C near the
Y-outfall. Concentrations of PCBs exceeding 1 mg/kg covered approximately 6.2 km2,
extending from the 8 transect to the 4 transect, primarily on the slope (Figure 1-9).
Concentrations of PCBs exceeding 0.3 mg/kg covered approximately 13.7 km2, extending from
the 9 transect to the 3 transect, encompassing the 61-m isobath and extending to the 200-m
isobath. Please note that in addition to the 2002/2004 LACSD data, Figure 1-9 uses two
simulated transects inserted between the 0 and 1 transects to approximate sediment
concentrations where no data exist. The simulated transects were set as an average of the 0 and
1 transect concentrations. Shoreline concentrations have been set at 0.05 mg/kg for contouring.
Table 1-1 provides a comparison of the area of surface contamination for DDTs and PCBs in
1992 and 2002/2004.
/MAY09PVS CHART 1.DOC/ 1-19
-------
1.0 INTRODUCTION DRAFT DEC08
TABLE 1-1: SURFACE CONTAMINATION AREA OF DOTS AND PCBS
DDTs PCBs
1992 Surface Sediment Data
2002/2004 Surface Sediment Data
Percent Reduction 1992 to 2002/2004
Area > 1 mg/kg
44.5 km2
39.1 km2
12%
Area > 10 mg/kg
8.2 km2
3.6 km2
56%
Area > 0.3 mg/kg
22.5 km2
13.7km2
49%
Area > 1 mg/kg
8.4 km2
6.2 km2
26%
1.2.4.2 Depth of Contaminants
Sediment core data collected by LACSD in 2001 are summarized in Figure 1-10. Average and
maximum concentrations of the dominant DDT isomer, p,p'-DDE (or DDE) are shown for 15-
cm depth intervals (0 to 15 cm, 16 to 30 cm, 31 to 45 cm and deeper until concentrations of DDE
remain below 1 ppm, assumed to indicate pre-effluent sediment) at selected LACSD sampling
stations, most of which are located along the 61-m isobath (C stations). In general, as shown in
Figure 1-10, the average and maximum DDE concentrations southeast of the outfalls were
highest in the shallow or surface sediment interval (0 to 15 cm). Northwest of the outfalls, the
highest concentrations occurred in the 16- to 30-cm or 31- to 45-cm intervals. The maximum
DDE concentration detected was 238 mg/kg, found at Station 8C in the 16- to 30-cm depth
interval.
No recent survey for PCBs at depth has been performed. However, Figure 1-11 shows sediment
core data collected by USGS in 1992 at 17 sampling stations located in water depths from 26 to
167 m. Average and maximum concentrations of PCBs are shown for 15-cm depth intervals. In
general, the average and maximum concentrations of PCBs southeast of the outfalls were
highest in the shallow or surface sediment interval (0 to 15 cm). Northwest of the outfalls, the
highest concentrations of PCBs occurred in the 16- to 30-cm or the 31- to 45-cm intervals. The
highest average concentrations of PCBs were at stations located between or immediately
northwest of the outfalls, with the average interval concentrations ranging from 1.3 to 18
mg/kg. The highest concentrations of PCBs were located in water depths between 50 and 60 m;
the maximum concentration of PCBs (20.6 mg/kg) was found along the 56-m isobath at
Station 564 in the 31- to 45-cm sediment depth interval.
1.2.5 Sediment Transport and Fate
1.2.5.1 Oceanographic Processes
Sediment transport on the PV Shelf is believed to follow the predominant direction of the near-
bottom flow, extending northwestward along the shelf (Drake et al. 1994). The Portuguese Bend
landslide and the White Point outfalls effluent have dominated the recent supply of solids to the
PV Shelf. Since 1988, the rate of erosion from the Portuguese Bend landslide has decreased as a
result of stabilization projects, which reduced movement to about 10 percent of former rates.
Redondo Canyon and San Pedro Canyon bound the PV Shelf Study Area to the northwest and
southeast, respectively, and limit sediment transported from adjacent shelf areas. Los Angeles-
Long Beach Harbor and its breakwater limit nearshore sediment transport (Drake et al. 1994).
1-20 /MAY09PVS CHAPT1.DOC
-------
Source: Lee et al., The Distribution and Character of Contaminated
Effluent-affected Sediment, Palos Verdes Margin, Southern
California, 1994
Note: The deepest data shown are either for the deepest
data available or where the concentrations of DDTs stayed
below 1.0 mg/kg, which is indicative of pre-effluent sediment.
Data are reported as dry weight.
Station 533 -167m -1992
Depth (cm)
Oto15
1 6 to 28
Average
DDTs (mg/kg)
8.480
12.440
Maximum
DDTs (mg/kg)
11.200
25.500
Station 522 - 57 to 59 m -1992
Depth (cm)
Oto15
16 to 30
31 to 48
DDTs (mg/kg)
3.907
4.835
8.001
Maximum
DDTs (mg/kg)
5.5
22.3
18.2
Station 518-89m-1992
Depth (cm)
Oto12
Average
DDTs (mg/kg)
3.700
DDTs (mg/kg)
6.070
Station 532-137m-1992
Depth (cm)
Oto15
16 to 32
Average
DDTs (mg/kg)
7.988
DDTs (mg/kg)
8.870
31.400
Station 523 -141 to 59 m -1992
Depth (cm)
Oto15
Average
DDTs (mg/kg)
5.333
Maximum
DDTs (mg/kg)
Station 514 - 53 m -1992
Depth (cm)
Oto15
Average
DDTs (mg/kg)
3.27
Maximum
DDTs (mg/kg)
5.06
1.53
Station 539 - 44 it
Depth (cm)
Oto15
1 6 to 30
31 to 44
45 to 60
Average
DDTs (mg/kg)
3.173
3.883
4.66
9.933
-1992
Maximum
DDTs (mg/kg)
4.06
4.23
4.82
16.2
Station 534 - 38 m - 1992
Depth (cm)
Oto15
to 30
31 to 48
Average
DDTs (mg/kg)
1.9
2.79
3.68
Maximum
DDTs (mg/kg)
3.63
6.12
Station 550 - 57 m - 1992
Depth (cm)
Oto15
1 6 to 30
31 to 45
Average
DDTs (mg/kg)
8.574
14.99
38.78
Maximum
DDTs (mg/kg)
14.7
35.3
148
Station 547 - 26 m - 1992
Depth (cm)
Oto15
16 to 24
Average
DDTs (mg/kg)
9.729
2.474
Maximum
DDTs (mg/kg)
43.6
7.39
Station 554 - 28 m -1992
Depth (cm)
Oto15
16 to 32
Station 536 - 65 m - 1992
Depth (cm)
Oto15
1 6 to 30
31 to 40
Average
DDTs (mg/kg)
5.56
18.71
36.62
Maximum
DDTs (mg/kg)
8.51
65.4
55.6
Station 542 -207m -1992
Depth (cm)
Oto4
Average
DDTs (mg/kg)
1.880
Maximum
DDTs (mg/kg)
1.880
Average
DDTs (mg/kg)
0.812
1.581
DDTs (mg/kg)
1.19
2.77
Station 555 -42m -1992
Depth (cm)
Oto15
1 6 to 30
31 to 40
Average
DDTs (mg/kg)
2.179
4.033
4.354
Maximum
DDTs (mg/kg)
4.5
4.81
4.98
Station 564 - 56 m - 1992
Depth (cm)
Oto15
1 6 to 30
31 to 45
Average
DDTs (mg/kg)
12.63
107.4
59.66
Maximum
DDTs (mg/kg)
27.1
305
200
A
Station 552-192m-1992
Depth (cm)
Oto15
16 to 24
Average
DDTs (mg/kg)
18.93
4.35
uses
CONTOUR LINES (m)
= 10 mg/kg < DDTs < 100 mg/kg
= DDTs > 100 mg/kg
.5
I Miles
SLC \\ SLCDB\GIS\PROJECTS\EPA PALOS VERDES\MAPFILES\PVS_DDTUSGS.MXD 11/16/2006 MSLAYDEN
DDTs (mg/kg)
43.6
7.39
Station 557- 104m-1992
Depth (cm)
Oto15
16 to 30
Average
DDTs (mg/kg)
65.01
Maximum
DDTs (mg/kg)
108
31 to 38 9.93 29.8 »
Station 556 - 56 to 57m - 1992
Depth (cm)
Oto15
1 6 to 30
31 to 45
Average
DDTs (mg/kg)
12.02
22.68
53.7
Maximum
DDTs (mg/kg)
35.6
118
253
Station 566 - 181 m - 1992
Depth (cm)
Oto16
Average
DDTs (mg/kg)
6.435
Maximum
DDTs (mg/kg)
16.1
J
Station 574 - 58 m - 1992
Depth (cm)
Oto15
1 6 to 30
31 to 36
Average
DDTs (mg/kg)
43.21
13.24
3.36
Maximum
DDTs (mg/kg)
97.8
49.1
3.36
Station 570 - 74 m - 1992
Depth (cm)
Oto15
1 6 to 32
Average
DDTs (mg/kg)
5.953
10.04
Maximum
DDTs (mg/kg)
19.1
18.1
Station 577 - 66 m - 1992
Depth (cm)
Oto15
1 6 to 28
Average
DDTs (mg/kg)
6.053
0.898
Max mum
DDTs i mg/kg)
9,92
2,26
Station 571 - 144 m - 1992
Depth (cm)
Oto15
1 6 to 20
Average
DDTs (mg/kg)
18.41
1.13
Maximu n
DDTs (mg/kg)
33.8
1.13
FIGURE 1-7
Concentrations of DDTs - USGS
1992 Sediment Cores
Palos Verdes Shelf Study Area
Feasibility Study
CH2IVIHILL
ES042007001SC0335398.RR.01 PVS 0050 FS.ai 6/07
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1.0 INTRODUCTION DRAFT DEC08
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1-22 /MAY09PVS CHAPT1.DOC
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PALOS VERGES
PENINSULA
Point
Vicente
SURFACE SEDIMENT (0 - 2 CM)
CONTOURS OF DDTs, 0-200 M WATER
DEPTH (mg/kg DW)
Sediment Sample Locations
— Outfalls
^B 0-0.05
^| 0.05 -0.1
Q^ 0.1-0.2
I | 0.2 - 0.5
I I 0.5 - 1
I J1-1.5
^1.5-3
I 13-10
^10-25
Note: In addition to the 2002/2004 LACSD data, this figure uses four Bight '94 samples, one 1993 LACSD sample, and two 1992 NOAA samples to provide actual
concentrations of DDTs between the 0 and 1 transects and north of the 0 transect. Shoreline concentrations have been set at 0.05 mg/kg for contouring.
ES042007001SC0335398.RR.01 PVS 0039b FS.ai 5/07
FIGURE 1-8
Surface Sediment Contours of DDTs -
2002/2004 Average
Pa/os Verdes Shelf Study Area
Feasibility Study
CH2MHILL
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1.0 INTRODUCTION DRAFT DEC08
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1-24 ES042007001SCO/DEC08PVS CHART 1.DOC/071300006
-------
PALOS VERGES
SURFACE SEDIMENT (0 - 2 CM)
CONTOURS OF PCBs, 0-200 M WATER
DEPTH (mg/kg DW)
X Sediment Sample Locations
— Outfalls
^H 0 - 0.05
|H 0.05 - 0.075
^| 0.075 - 0.1
I 10.1-0.15
I 10.15-0.2
I 10.2-0.3
I 10.3-0.5
I 10.5 - 0.75
I 10.75 -1
I 11-1.25
j^B 1.25-1.5
Note: In addition to the 2002/2004 LACSD data, two simulated transects were inserted between the 0 and 1 transects to approximate sediment concentrations where no data exist.
The simulated transects were set as an average of the 0 and 1 transect concentrations. Shoreline concentrations have been set at 0.05 mg/kg for contouring.
ES042007001SC0335398.RR.01 PVS 0038b FS.ai 5/07
FIGURE 1-9
Surface Sediment Contours of PCBs -
2002/2004 Average
Pa/os Verctes Shelf Study Area
Feasibility Study
CH2MHILL
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1.0 INTRODUCTION DRAFT DEC08
This page intentionally blank
1-26 ES042007001SCO/DEC08PVS CHART 1.DOC/071300006
-------
Note: The deepest data shown are either for the deepest
data available or where the DDE concentrations stayed
below 1.0 mg/kg, which is indicative of pre-effluent sediment.
Data are reported as dry weight.
Station 7C - 60m -2001
Depth (cm)
Oto 15
16 to 30
31 to 45
46 to 50
Average
DDE (mg/kg)
10.8
87.4
32.5
1.02
Maximum
DDE (mg/kg)
79
210
143
1.02
Station 2C - 60 m - 2001
Depth (cm)
Oto 15
16 to 30
31 to 38
Average
DDE (mg/kg)
1.9
5.1
1.17
Maximum
DDE (mg/kg)
2.72
9.07
1.39
Station 3C - 60 m - 2001
Depth (cm)
Oto 15
1 6 to 30
31 to 45
46 to 58
Average
DDE (mg/kg)
2.37
9.68
3.09
0.75
Maximum
DDE (mg/kg)
3.67
25.5
17.3
1.19
LACSD
CONTOUR LINES (m)
Station 4C - 60 m - 2001
Depth (cm)
Oto 15
16 to 30
31 to 45
46 to 58
Average
DDE (mg/kg)
2.75
7.57
17.5
0.97
Maximum
DDE (mg/kg)
4.24
19.2
36.3
1.7
- / ~v_ x
Station 5C - 60 m - 2001
Depth (cm)
Oto 15
16 to 30
31 to 45
46 to 66
Average
DDE (mg/kg)
3.71
10.01
44.9
6.77
Maximum
DDE (mg/kg)
4.89
20
74.3
39.4
^ ~
"^-\
^
*7
\*n*
^
Station 85C - 60 m - 2001
Depth (cm)
Oto 15
1 6 to 24
Average
DDE (mg/kg)
2.6
1.36
Maximum
DDE (mg/kg)
10.4
2.12
Station 9CD - 50 m - 2001
Depth (cm)
Oto 15
16 to 30
31 to 44
Average
DDE (mg/kg)
1.31
3.26
3.96
Maximum
DDE (mg/kg)
2.6
10.3
9.42
Station 9C - 60 m - 2001
Depth (cm)
Oto 15
16 to 30
31 to 40
Average
DDE (mg/kg)
4.01
1.21
0.74
Maximum
DDE (mg/kg)
13.4
2.45
1.59
- 10 mg/kg < DDE < 100 mg/kg
- DDE > 100 mg/kg
2.5
I Miles
\\galt\gis2\335398PalosVerde\2006\MapFiles\Dec06\pvs_Fig04_6_ddtLACSD_BL.mxdtfaludy
Station 925C - 60 m - 2001
Depth (cm)
Oto 15
16 to 30
31 to 33
Average
DDE (mg/kg)
3.38
1.43
1.34
Maximum
DDE (mg/kg)
15.4
5.22
1.49
Station 8C - 60 m - 2001
Depth (cm)
Oto 15
1 6 to 30
31 to 45
46 to 72
Average
DDE (mg/kg)
88.7
150.1
102.6
27.4
Maximum
DDE (mg/kg)
198
238
143
75.8
Station 9CB- 70m -2001
Depth (cm)
Oto 15
16 to 22
Average
DDE (mg/kg)
2.4
0.97
Maximum
DDE (mg/kg)
8.28
1.31
Station 95C- 60m -2001
Depth (cm)
Oto 15
Average
DDE (mg/kg)
1.56
?3n\
kH^(
Maximum
DDE (mg/kg)
3.93
FIGURE 1-10
DDE Concentrations- LACSD 2001
Sediment Cores
Pa/os Verdes Shelf Study Area
Feasibility Study
CH2IWHILL
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1.0 INTRODUCTION DRAFT DEC08
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1-28 ES042007001SCO/DEC08PVS CHART 1.DOC/071300006
-------
Station 536 - 65 m - 1992
Depth (cm)
Oto15
1 6 to 30
31 to 40
Average
PCBs (mg/kg)
0.585
2.168
3.599
Maximum
PCBs (mg/kg)
0.943
4.97
5.29
Source: Lee et al., The Distribution and Character of Contaminated
Effluent-affected Sediment, Palos Verdes Margin, Southern
California, 1994
Note: The deepest data shown are either for the deepest
data available or where the concentrations of PCBs stayed
below 1.0 mg/kg, which is indicative of pre-effluent sediment.
Data are reported as dry weight.
Station 534 -38m -1992
Depth (cm)
Oto15
1 6 to 30
31 to 48
Average
PCBs (mg/kg)
0.265
0.372
0.497
Maximum
PCBs(mg/kg)
0.323
0.492
0.818
I
Station 539 -44m -1992
Depth (cm)
Oto15
16 to 30
31 to 44
45 to 60
Average
PCBs (mg/kg)
0.361
0.463
0.531
1.363
Maximum
PCBs (mg/kg)
0.419
0.510
0.553
2.270
Station 514 -53m -1992
Depth (cm)
Oto15
1 6 to 30
31 to 45
Average
PCBs (mg/kg)
0.422
0.544
0.115
Maximum
PCBs (mg/kg)
0.489
0.780
0.115
Station 547 - 26 m - 1992
Depth (cm)
Oto15
16 to 24
Average
PCBs(mg/kg)
0.871
0.217
Maximum
PCBs (mg/kg)
3.730
0.593
Station 554 - 28 m - 1992
Depth (cm)
Oto15
1 6 to 32
Average
PCBs (mg/kg)
0.103
0.157
Maximum
PCBs (mg/kg)
0.155
0.211
Station 518 -89m -1992
Depth (cm)
Oto12
Average
PCBs (mg/kg)
0.506
Maximum
PCBs (mg/kg)
0.851
Station 532 -137m -1992
Depth (cm)
Oto15
1 6 to 32
Average
PCBs (mg/kg)
0.92
2.182
Maximum
PCBs (mg/kg)
1.04
3.55
5
~v
Station 523 -141 to 59 m -1992
Depth (cm)
Oto15
Average
PCBs (mg/kg)
0.643
Maximum
PCBs (mg/kg)
1.3
Station 564 - 56 m - 1992
Depth (cm)
Oto15
16 to 30
31 to 45
Average
PCBs (mg/kg)
1.756
6.200
6.217
Maximum
PCBs (mg/kg)
2.730
13.900
20.600
A
Station 533 -167m -1992
Depth (cm)
Oto15
1 6 to 28
I
—-J
Average
PCBs (mg/kg)
1.353
1.961
Maximum
PCBs (mg/kg)
2.44
4.31
,---'
Station 542 -207m -1992
Depth (cm)
Oto4
Average
PCBs (mg/kg)
0.163
Maximum
PCBs (mg/kg)
0.163
Station 566- 181 m- 1992
Depth (cm)
Oto16
Average
PCBs(mg/kg)
0.680
Maximum
PCBs (mg/kg)
1.940
Station 574 - 58 m - 1992
Depth (cm)
Oto15
1 6 to 30
31 to 45
Average
PCBs (mg/kg)
4.524
2.377
0.425
Maximum PCBs
(mg/kg)
7.610
4.160
0.425
uses
CONTOUR LINES (m)
Station 552 -192m -1992
Depth (cm)
Oto15
16 to 24
Average
PCBs (mg/kg)
1.666
0.347
Maximum
PCBs (mg/kg)
3.730
0.593
v- — —
A^V A
Sta
tion 577 - 66 n
1 - 1992
Station 570- 74m -1992
Oto15
1 6 to 32
Average
1.406
1.571
Maximum
PCBs(mg/kg)
3.680
3.340
- 10 mg/kg < PCBs < 100 mg/kg
- PCBs > 100 mg/kg
.5
I Miles
SLC \\SLCDB\GIS\PROJECTS\EPA PALOS VERDES\MAPFILES\PVS_PCBUSGS.MXD 11/16/2006 MSLAYDEN
Station 550 - 57 m - 1992
Depth (cm)
Oto15
1 6 to 30
31 to 45
Average
PCBs(mg/kg)
1.312
1.929
6.022
Maximum
PCBs (mg/kg)
3.660
4.440
18.400
Station 557- 104m -1992
Depth (cm)
Oto15
1 6 to 30
31 to 38
Average
PCBs (mg/kg)
1.565
8.970
2.673
Maximum
PCBs (mg/kg)
3.940
12.600
4.150
Depth (cm)
Oto15
16 to 28
PCBs (mg/kg)
0.812
0.197
PCBs (mg/kg)
1.470
0.300
Station 571 - 1*44 m - 1992
Oto15
1 6 to 20
Average
PCBs(mg/kg)
1.471
0.111
Maximum
PCBs(mg/kg)
2.890
0.111
FIGURE 1-11
Concentrations of PCBs - USGS
1992 Sediment Cores
Palos Verdes Shelf Study Area
Feasibility Study
CH2IVIHILL
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1.0 INTRODUCTION DRAFT DEC08
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/MAY09PVS CHAPT1.DOC
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1.0 INTRODUCTION
Knowledge of the oceanographic processes that govern resuspension and transport of bottom
sediment on the PV Shelf is primarily based on the following historical studies:
1. Pre-1990 oceanographic studies of tidal and low-frequency current regimes in the PV Shelf
region, as derived from time-series current measurements at a limited number of locations
and for relatively short time periods (e.g., well less than one year).
2. Extensive oceanographic and geotechnical field studies that were conducted on the PV Shelf
in 1992-1993 by USGS and reported in a special volume of Continental Shelf Research
dedicated to PV research topics (CSR, 2002). Current data acquired during these studies
were sufficient to assess forcing mechanisms having seasonal, synoptic, and tidal periods.
However, the measurements were limited in their vertical resolution, near-bottom
measurements were lacking, and the sampling rates were insufficient for analysis of high-
frequency processes.
3. In 2004, USGS and SAIC undertook an oceanographic measurement program from mid-
February to July that was focused on making multiple-parameter, high-frequency
measurements in the bottom boundary layer to capture sediment resuspension events and
the physical processes responsible for those events. This program furthered our
understanding of oceanographic processes and geotechnical properties of the sediment.
Key elements of the oceanographic conditions on the PV Shelf, as based upon these studies, are
given below:
• The magnitude and frequency of tidal currents on the PV Shelf and upper slope are well
documented by field observations. The most dominant tidal constituent is the MS semi-
diurnal tide with a magnitude of approximately 5 centimeters per second (cm/s) and period
of approximately 12.4 hours (hrs). Tidal currents alone are not sufficient to resuspend
sediments.
• Sub-tidal (low frequency) currents on the PV Shelf are predominantly northwestward and
relatively weak, with mean velocities of 4 to 5 cm/s at mid-depth and 3 to 4 cm/s near the
bottom. Data collected by Wiberg (2002) on two sites (figure 1-12) measured mean
alongshelf velocity of 1.9 to 3.2 cm/sec to the northwest at Site B, and 0 to 1.4 cm/sec across-
shelf in the seaward direction. Mean current speed (regardless of direction) at Site B was 7.9
to 9.8 cm/sec. At Site D, mean along-shelf velocity was 4.1 to 4.2 cm/sec along shelf to the
northwest and 0.2 to 0.4 cm/sec across-shelf in the landward direction. Mean current speed
regardless of direction at Site D was 9.6 to 10.7 cm/sec.
• Current fluctuations typically reach speeds of 20 to 30 cm/s. Fluctuations in these low-
frequency, along-shelf currents often occur at periods of 5 to 20 days and are independent of
season. Sub-tidal cross-isobath currents are much weaker. The low-frequency currents on
the PV Shelf are driven by the along-shelf pressure gradient more so than by local winds.
• Data from LACSD moorings show that current speeds are less than 20 cm/sec more than 98
percent of the time and are smaller than 25 cm/sec more than 99 percent of the time.
• LACSD current monitoring stations extended further south than those of the USGS 1992-
1993 study. Data from the southern stations indicated increased near-bottom velocities
compared with sites at and northwest of the outfalls. Near-bottom currents in excess of 15
cm/sec were recorded only 5.9 percent and 8.8 percent of the time northwest of the outfalls
at Stations A3 and A4, respectively. Near the diffuser at Station 5A, 9.2 percent of the near-
/MAY09PVS CHART 1.DOC/
-------
1.0 INTRODUCTION DRAFT DEC08
bottom observations were above 15 c/sec. Near-bottom currents at Stations A6 and A7,
southeast of the outfall, were above 15 cm/sec 15 percent and 36 percent of the time.
• Subtidal currents were aligned roughly with the isobaths with a tendency for currents to
flow offshore (northwestward) near Point Vicente as the isobaths bend northeastward
(Noble et al., 2002). Noble also reported that because the shelf narrows toward the
northwest near Point Vicente, the subtidal along-shelf currents were stronger near Site D
than near the Site B. Wiberg et al. (2002) reported similar findings indicating that mean
along-shelf currents were greater at Site D than Site B, and mean across-shelf current was
weakly onshore at Site D and offshore at Site B.
• Wave data from offshore buoys combined with numerical model predictions suggest that
ambient bottom sediments on the PV Shelf will be resuspended at sites having water depths
of 60 m or less when impacted by large-amplitude waves (swell) having periods in excess of
9 sec and wave orbital velocities exceeding 14 cm/s.
• Waves having the potential to resuspend bottom sediment at the 60-m depth occur, on
average, 10 times per year, with a mean duration of 1.6 days. The average time between
these events during winter is 8 days. Wave-driven resuspension normally does not occur
during summer. Wave-driven sediment resuspension is very rare for water depths greater
than 100 m on the outer PV Shelf.
• Currents are generally not of sufficient strength to mobilize (scour or erode) sediment in the
area. LACSD current meter data indicate occasional periods of stronger currents that could
result in some sediment mobilization. However, the frequency and duration of these events
limit their significance.
• Increased river discharge during meteorological storms does not significantly effect PV
Shelf currents.
1.2.5.2 Sediment Physical Characteristics
PV Shelf sediment samples have been collected for analysis of physical characteristics on a
semiannual basis from the summer of 1992 through the winter of 2005. Sediment particle size
distribution was calculated according to the Wentworth grain size scale to determine the mean
percent dry mass of gravel (sediment with grain size greater than 2,000 micrometers [|am]), sand
(2,000 (am > grain size > 63 (am), silt (63 (am > grain size > 4 (j.m), and clay (grain size less than 4
(j.m) in samples collected over the 14-year history of the semiannual sampling events (27 total).
Samples were not collected from all locations during every event; however, each location was
sampled 21 to 23 times. The sediment particle size distribution for samples collected at LACSD
sampling stations is shown in Table 1-2.
In general, sediment along the 30-m isobath (D stations) contain a higher percentage of coarse-
grained material (gravels and sands with grain size greater than 63 (am). Previous studies of the
PV Shelf Study Area have concluded that strong wave-generated currents are common on the
inner shelf and, as a result, resuspension of sediment is common (Kolpack, 1987). This causes a
greater turnover in fine-grain sediment and, as a result, the percentage of coarse-grain sediment
is greater. Sediment samples collected along the 61- and 152-m isobaths (B and C stations,
respectively) tend to consist of primarily fine-grained sediment (silts and clays with grain size
less than 63 (am). The exceptions to these trends are Stations 2C, 9C, IOC, and 10B, which each
consist of greater than 50 percent coarse material.
1-32 /MAY09PVS CHAPT1.DOC
-------
- 33° 50'
118° 30'
118° 20'
Santa Monica
Bay
LOS ANGELES
COUNTY
Palos Verdes Peninsula
Los Angeles
Harbor
Palos Verdes
Shelf Study Area
O Site B - Monitoring Site
Source: Wibergetal., 2002.
ES102006019/SC0335398.RR.01 PVS_0030 Rl.ai 6/07
FIGURE 1-12
Monitoring Sites Used by Wiberg et al. (2002)
Palos Verdes Shelf Study Area
Feasibility Study
CH2MHILL
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1.0 INTRODUCTION DRAFT DEC08
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1-34 /MAY09PVS CHAPT1.DOC
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TABLE 1-2
Sediment Physical Characteristics
Cell
OB
OC
OD
1B
1C
1D
2B
2C
2D
3B
3C
3D
4B
4C
4D
SB
5C
5D
6B
6C
6D
7B
7C
7D
SB
8C
8D
9B
9C
9D
10B
10C
10D
Particle Size Distribution (%) 1| 2
Gravel3
(mean %)
0.04
0.34
0.00
0.19
0.03
1.20
0.18
0.17
8.43
0.07
0.08
0.05
0.39
0.08
0.02
0.52
0.01
0.11
0.36
0.16
0.03
0.33
0.08
0.12
0.26
1.40
0.03
0.19
0.06
0.00
0.04
0.32
0.02
(StDev)
0.11
1.35
0.00
0.30
0.13
2.33
0.20
0.21
5.65
0.09
0.15
0.08
0.51
0.18
0.05
1.38
0.03
0.15
0.54
0.63
0.06
0.53
0.18
0.15
0.35
1.57
0.03
0.38
0.23
0.01
0.09
0.63
0.04
Sand3
(mean %)
15.77
28.26
74.84
45.53
40.88
88.59
45.58
56.12
87.42
29.48
39.06
79.07
13.12
21.60
62.91
14.74
17.84
62.25
16.81
21.16
69.95
19.01
37.01
75.87
19.64
36.40
83.56
24.48
53.92
76.39
54.37
76.90
73.88
(StDev)
5.22
4.05
5.57
4.71
4.51
5.63
7.63
5.10
5.81
6.39
5.20
3.62
4.77
5.40
6.38
6.80
3.81
8.83
6.63
4.37
6.26
6.44
22.55
10.25
6.43
7.96
5.43
6.35
4.41
3.28
5.61
6.90
4.36
Silt3
(mean %)
63.63
59.77
20.64
39.12
45.28
6.04
38.14
29.69
1.65
51.40
42.60
12.16
61.68
59.28
24.31
60.10
62.70
24.99
58.53
59.59
21.35
55.41
46.53
16.87
55.97
45.18
11.15
53.64
36.77
17.61
32.85
16.32
18.44
(StDev)
3.12
3.55
4.67
4.01
4.20
3.49
4.91
3.39
1.31
6.03
3.80
2.07
5.17
4.76
4.61
6.63
3.80
5.88
5.87
4.34
4.63
5.14
16.53
7.27
5.25
6.22
4.26
5.54
3.83
2.69
4.52
5.52
3.37
Clay3
(mean %)
20.54
11.61
4.49
15.14
13.79
4.14
16.08
14.00
2.49
19.03
18.23
8.71
24.79
19.02
12.75
24.62
19.43
12.63
24.28
19.07
8.65
25.22
16.37
7.13
24.11
17.00
5.24
21.67
9.24
5.98
12.72
6.44
7.65
(StDev)
3.00
1.37
1.13
2.13
1.60
1.30
3.69
2.16
1.57
3.05
2.17
1.78
3.46
2.38
2.37
2.94
2.15
3.19
3.58
1.72
2.14
2.93
6.47
3.17
2.99
2.89
1.42
3.15
2.08
0.95
1.86
1.35
1.33
Particle Distribution
Summary4
% Course
15.81
28.61
74.85
45.72
40.91
89.79
45.76
56.29
95.84
29.55
39.14
79.11
13.52
21.68
62.93
15.26
17.85
62.36
17.17
21.32
69.98
19.34
37.09
75.99
19.90
37.80
83.60
24.67
53.98
76.39
54.41
77.22
73.90
% Fines
84.17
71.38
25.14
54.26
59.07
10.19
54.22
43.69
4.14
70.43
60.84
20.87
86.46
78.30
37.06
84.72
82.13
37.62
82.81
78.66
30.01
80.64
62.89
24.00
80.08
62.19
16.38
75.31
46.01
23.60
45.57
22.76
26.08
Data collected by the LACSD semiannually between summer 1992 and winter 2005.
2 Mean particle size and standard deviation determined using a minimum of 21 samples.
3 Grain size defined as follows: gravel < 500 |jm < sand < 63 |jm < silt < 4 |jm < clay
'Summary shows a comparison between percentage course-grained material (gravel and sand) and percentage fine-grained
material (silt and clay).
1-35
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1.0 INTRODUCTION
1.2.5.3 Chemical Transformation of Contaminants
DDTs and PCBs are considered to be highly persistent in the environment. However, under
appropriate conditions, they may be transformed through a variety of processes to other related
chemicals called "daughter products." The following conclusions can be made about the
degradation of DDTs and PCBs at the PV Shelf:
• The primary DDT compound observed in EA sediments is DDE. Data indicate that the
DDT-contaminated effluent discharged onto PV Shelf was transformed relatively rapidly
from DDT to DDE in the deposited sediments (Eganhouse et al., 2000).
• Laboratory studies using sediment collected from PV Shelf have shown that biochemical
transformation (reductive dechlorination) of DDE to DDMU (l-chloro-2,2-bis [p-chlorophenyl]
ethylene) can occur in PV Shelf EA sediments. The calculated first-order half-lives for DDE
transformation to DDMU in these laboratory experiments ranged from 3 to 10 years and are
considered to be upper limits on the transformation rate that might be observed
(CH2M HILL, 2007).
• USGS studies of PV Shelf sediment in 1992 observed the presence of DDMU throughout the
EA deposit. Sediment core data from two areas investigated in 2003 have shown that the
inventory of DDE has decreased since 1992 while that of DDMU has increased. Sediment
cores taken in 1992 and 2003 by USGS near LACSD Station 3C show that, while recalcitrant
compounds such as PCBs and certain branched long-chain alkylbenzenes (e.g., TABS) have
very similar inventories (within 5 percent) in the two cores, the inventory of p,p'-DDE has
decreased (43 percent) while the inventories of the degradation products, DDMU and
DDNU (unsym-bis [p-chlorophenyl] ethylene), have increased by 34 and 33 percent,
respectively. Although this was a limited study, it supports the hypothesis that DDE is
breaking down in the PV Shelf sediment and warrants further investigation (Eganhouse and
Pontolillo, 2007).
• DDMU, DDNU and other daughter products are not classified as toxic substances; however,
research on these substances is scant. Thus, the relative importance of these transformations
to any associated changes in human or ecological risk is unknown and warrants additional
study.
• The congener-specific compositions of PCBs in shelf sediments are highly uniform and no
temporal changes have been observed in the congener distribution profiles for PV Shelf
sediment cores at depth. Therefore, there is no evidence that PV Shelf PCBs are degrading.
However, PCB concentrations in surface sediments have dropped over time due to other
loss processes, i.e., mixing, dispersal.
Additional assessment of the longterm fate of the contaminated sediment deposit and its risk to
human health and the environment is found in Section 2.0.
/MAY09PVS CHART 1.DOC/ 1-37
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1.0 INTRODUCTION DRAFT MAY09
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2.0 Risk Assessments and Predictive
Modeling of Future Conditions
This section describes the risk assessments and models used to provide an evaluation of the
potential threat to human health and the environment posed by the PV Shelf superfund site
in the absence of any remedial action. Risk assessments address toxicity and levels of
hazardous substances present in relevant media, (e.g., water, sediment, and biota), potential
human and environmental receptors and exposure routes, and extent of expected impact or
threat. Along with a quantification of current risk, this section presents predictive modeling
of future conditions of the site to assist in the selection of remedial actions to eliminate,
reduce or control these risks.
2.1 Summary of Risk Assessments
This section summarizes the 1999 Human Health Risk Evaluation plus its 2006 update, and
the 2003 Ecological Risk Assessment. The section also discusses the 2002-2004 Southern
California Coastal Marine Fish Contaminants Survey (EPA, 2007), LACSD contaminant trends
in fish, recent fish-in-market analyses, and application of a bioaccumulation model
(HydroQual, 1997) to establish a relationship between contaminant concentrations in fish
tissue and sediment (Anchor QEA, 2009).
The risk assessments concluded that fish consumption is the exposure pathway that poses
the greatest level of risk to receptors. The contaminants of concern (COC) are DDT and its
metabolites, herein referred to as DDTs, and PCBs. Both PCBs and DDTs are classified as
probable human carcinogens (USEPA, 1991, USEPA, 1997 d).
2.1.1 1999 Human Health Risk Evaluation
A streamlined Human Health Risk Evaluation (HHRE) was conducted for the PV Shelf site
in 1999, in accordance with the Guidance on Conducting Non-Time-Critical Removal Actions
under CERCLA (EPA, 1993a). The purpose of the 1999 HHRE was to summarize, using
existing data, the human health risks posed by contaminated effluent-affected (EA)
sediment on the PV Shelf. The HHRE was based on historical data from a variety of
sources, including the following:
• LACSD NPDES bioaccumulation monitoring reports (LACSD, various years) and
other data collected by LACSD, which include fish tissue concentration data for
white croaker, kelp bass, black surfperch, and California halibut.
• California OEHHA Study of Chemical Contamination of Marine Fish from Southern
California (Pollock et al., 1991), which reports tissue concentration data in 16 fish
species from 24 sites in Southern California, including locations on the PV Shelf.
• Santa Monica Bay Seafood Consumption Study (Santa Monica Bay Restoration Project
[SMBRP], 1994), which describes fish consumption patterns and rates in areas
including the PV Shelf.
MAY09PVS FS CHART 2.DOC/ 2-1
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
The HHRE focused on the consumption of contaminated fish as the primary exposure
pathway. Potential risks to human health are due to the consumption of fish that have
bioaccumulated contaminants from sediment and sediment-dwelling prey. The evaluation
included a quantitative assessment of the following:
• Human health risks from the chemicals of greatest concern: Although other
contaminants are present in PV Shelf sediment and fish tissue, potential risks due to
DDT and its metabolites (referred to collectively as DDTs) and PCBs are significantly
higher and, therefore, the HHRE focused on these compounds.
• Human health risks due to the most significant exposure route: Although other routes
of exposure to DDTs and PCBs in sediment or fish may be possible, consumption of
contaminated fish by recreational anglers is believed to be the most significant exposure
pathway and, therefore, was evaluated quantitatively in this HHRE. Although
subsistence fishing may occur in the PV Shelf area, site-specific (e.g., Santa Monica Bay
area) fish consumption data were available for recreational anglers only. A qualitative
assessment of the potential risk to nursing infants was also conducted.
• Reasonable Maximum Exposure (RME) and Central Tendency (CT) scenarios: In
accordance with EPA guidance (EPA, 1995b and 1995c), a high-end exposure scenario
was evaluated to ensure the assessment was protective of human health. The RME
scenario is an exposure scenario based on single-species consumption rates (i.e.,
consumption rates averaged over anglers who consume a particular species). In
addition, a CT exposure scenario was evaluated, using average and/or median values
for exposure parameters. The CT, or average, scenario assumed a mixed-species diet
and used median consumption rates averaged over all boat anglers (EPA, 1995b).
2.1.1.1 Exposure Assessment
The 1999 HHRE considered consumption of the 12 species of fish most commonly
consumed by Santa Monica Bay boat anglers, based on information collected for the Santa
Monica Bay Seafood Consumption Study (SMBRP, 1994). Fish tissue concentrations of DDTs
and PCBs for these 12 species were based on data collected by the LACSD (white croaker,
kelp bass, California halibut, surfperch) and for the OEHHA Comprehensive Study (barred
sandbass, California scorpionfish, California sheephead, chub mackerel, halfmoon, Pacific
barracuda, Pacific bonito, and rockfishes [Pollock et al., 1991]).
Fish consumption rates were based on 338 boat anglers who reported consuming fish in the
previous 4 weeks (28 days) in the Santa Monica Bay Seafood Consumption Study (SMBRP,
1994). An RME scenario was evaluated for each of the 12 fish species included in the HHRE;
consumption rates were based on consumers of a particular fish species. For example, 13
people reported eating white croaker during the previous 28 days. The average
consumption rate (estimated using the 95 percent upper confidence limit [UCL] on the
mean) of white croaker by these 13 white croaker consumers (27.9 grams per day [g/day])
was used to quantify the RME scenario for consumers of this species. This represents about
six 150-gram meals per month. The CTE scenario assumed that an angler would eat all 12
fish species, with consumption rates for each species calculated by multiplying the species
diet fraction by the median fish consumption rate for all 338 boaters. For example, white
croaker represents 2.2 percent, or 0.48 g/day, of the overall median fish consumption rate
(21.4 g/day) for boat anglers, based on the results of the SMBRP (1994) study. This
represents about one 175-gram meal (about 6 ounces) of white croaker every year.
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2. RISK ASSESSMENTS AND MODELING
Exposure durations used to quantify human health risks were based on the reported fishing
durations of boat anglers in the Santa Monica Bay Seafood Consumption Study (SMBRP, 1994).
Reported fishing duration reflected only the length of time the surveyed individuals had
been fishing up to the time of the survey. Because no information was available on how long
these individuals will continue to fish in the future, the reported fishing duration is not
equivalent to total exposure duration. The 90th percentile reported fishing duration of 30
years was used to quantify the RME scenario; the mean reported fishing duration of 13.8
years was used to quantify the CTE scenario. Exposure point concentrations were assumed
to remain constant for the selected exposure duration.
2.1.1.2 Risk Characterization
Because of fundamental differences in the mechanisms through which carcinogenic and
noncarcinogenic processes occur, risks are characterized separately for these two types of
health effects. Cancer risks and noncancer hazard quotients (HQs) were calculated for the
RME and CTE scenarios.
Potential health risks associated with carcinogens were estimated by calculating the
increased probability of an individual developing cancer during his or her lifetime as a
result of exposure to a carcinogenic compound. For example, a cancer risk of 2 x 10~6 means
that for every 1 million people exposed to the carcinogen during the agreed upon exposure
period (e.g., 30 years for RME scenario), the average incidence of cancer might increase by
two cases. EPA uses an excess lifetime cancer risk (ELCR) of 10~6 (one in 1,000,000) as the
point of departure for cancer risk estimates that are of concern. EPA uses an acceptable risk
range of 10~4 to 10~6 to determine whether a site poses a risk to human health (40 CFR
§300.430) (EPA, 1999).
For noncancer health effects, the likelihood that a receptor will develop an adverse effect
was estimated by comparing the predicted level of exposure for a particular chemical with
the highest level of exposure that is considered protective, i.e., the reference dose (RfD)
appropriate to that exposure period. When the estimated exposure exceeds the RfD, the HQ
of a chemical exceeds 1 (i.e., HQ > 1).
RME Scenario
The RME scenario represents the potential risks to boat anglers who consume a particular
species of fish collected from the PV Shelf, assuming mean tissue concentrations and
consumption rates (as represented by the 95 percent UCL on the mean). Cancer risks
exceeded 1 x 10~4 for consumers of the following fish species: white croaker (2 x 10~3) and
surfperches (2 x 10~4). Several species of fish posed a potential noncancer hazard under the
RME scenario: white croaker (HQ for PCBs = 32, HQ for DDTs = 17), surfperch (HQ for
PCBs = 5), barred sandbass (HQ for PCBs = 3), California halibut (HQ for PCBs = 3),
California sheephead (HQ for PCBs = 2), and kelp bass (HQ for PCBs = 2). This scenario
reflects consumption of a single species of fish using a conservative estimate of the mean
consumption rate (i.e., the 95 percent UCL) for that species. It should be noted, however,
that boat anglers generally do not consume only a single species of fish. For example, since
the 95 percent UCL on the mean total fish consumption rate (i.e., all species) is 53.0 g/day, a
consumer of white croaker (at the RME consumption rate of 27.9 g/day) also may be
consuming a variety of other fish species. The contribution of DDTs and PCBs in these other
fish species to human health risk is not reflected in the RME results.
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
CTE Scenario
The CTE scenario represents the potential risk to boat anglers who consume a mixed-species
diet of fish collected from the PV Shelf, assuming arithmetic mean tissue concentrations and
median consumption rates for all boat anglers (rather than for consumers of a particular
species). The total cancer risk (DDTs and PCBs combined) for anglers who fish from boats
(mixed-species diet) was 2 x 10~5. The noncancer HQs were 0.3 and 0.9 for DDTs and PCBs,
respectively. These HQs indicate that noncancer health hazards were not of concern.
Monte Carlo Simulation
In addition to the point estimate risk calculations described above, a Monte Carlo simulation
was performed to evaluate uncertainty and variability in the consumption of white croaker
by boat anglers. Results of the Monte Carlo simulation indicated that the mean cancer risk
is 3 x 10'4, and the 95th percentile cancer risk is 1 x 10~3. About 45 percent of simulation
results were above 1 x 10~4; in other words, a cancer risk of 1 x 10~4 corresponds to a 55th
percentile of the output distribution. The mean and median noncancer HQs (7 and 3,
respectively) are greater than 1, the level above which there may be a concern for potential
noncancer health effects. The 95th percentile HQ is 26. About 75 percent of simulation
results exceeded an HQ of 1 (i.e., an HQ of 1 corresponds to a 25th percentile of the output
distribution).
Sensitivity studies were performed to identify those input parameters that represent the
greatest contributors to variance in the cancer risk and noncancer hazard for recreational
boat anglers consuming white croaker. Exposure duration was the largest contributor to
variance in the cancer risk results, followed by DDTs and PCBs concentrations in white
croaker tissue. Tissue concentrations of DDTs and PCBs were the largest contributors to
variance in the noncancer hazard, followed by the white croaker consumption rate. These
exposure factors reflect both uncertainty and natural variability in a population.
Risk to Nursing Infants
The potential risks to breast-fed infants due to consumption of DDTs and PCBs in breast
milk were also evaluated. Results indicated that DDTs and PCBs breast milk concentrations,
based on maternal consumption of one 150-gram meal of white croaker per month, could be
as high as 0.8 mg/kg and 0.05 mg/kg, respectively. This corresponds to noncancer HQs of
220 and 370 for DDTs and PCBs, respectively. Based on maternal consumption of kelp bass,
noncancer HQs to an infant were 3 and 16 for DDTs and PCBs, respectively.
Uncertainty Analysis
An uncertainty analysis provides a qualitative and, where possible, semi-quantitative
evaluation of the assumptions and limitations inherent in each step of the risk assessment
process and their effects on the overall risks calculated for the site, particularly those
uncertainties not addressed as part of the Monte Carlo analysis. Uncertainties are
associated with each step of the risk assessment process, including data evaluation,
exposure assessment, toxicity assessment, and risk characterization. Uncertainties
associated with the human health risk assessments are discussed in section 2.1.2.3.
2.1.2 2006 Technical Memorandum (Supplemental HHRE)
The 1999 HHRE used available fish data. The purpose of the supplemental HHRE was to
update the analysis of human health risk using 2002 fish data from the 2002/2004 Southern
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2. RISK ASSESSMENTS AND MODELING
California Coastal Marine Fish Contaminants Study (EPA/MSRP 2007) and from LACSD 2002
fish monitoring data. The supplemental HHRE Technical Memorandum (TM) used ocean
fish data collected from the PV Shelf Study Area (from Point Fermin to Redondo Canyon).
2.1.2.1 Summary of Data Used
As mentioned above, data from two ocean fish sampling studies were used in the
Supplemental HHRE: the EPA/MSRP 2002/2004 ocean fish sampling effort, and the 2002
LACSDS ocean fish sampling study.
Since 1971, LACSD has monitored the marine environment on the PV Shelf to assess the long-
term environmental impacts form the effluent discharged from JWPCP outfalls. Regional
marine conditions in the area of the outfalls are monitored according to the requirements of
the LACSD NPDES permit. The permit includes monitoring requirements for accumulation
of DDTs and PCBs within tissues of various fish and invertebrate species. The purpose of the
monitoring is to evaluate temporal and spatial trends associated with bioaccumulation of
DDTs and PCBs in biota collected within three zones across the PV Shelf: Zone \, from White
Point to Bunker Point; Zone 2, from Long Point to Point Vicente; and Zone 3, from Palos
Verdes Point to Bluff Cove. The Supplemental HHRE includes white croaker and kelp bass
data collected in 2002 from these three zones. In 2002, LACSD analyzed fish tissue for DDTs
and PCBs as the sum of Aroclors (Aroclors 1016,1221,1232,1242,1248,1254,1260).
The 2002/2004 Southern California Coastal Marine Fish Contaminants Survey (EPA/NOAA 2007)
caught 23 species of fish from Ventura to Orange counties. The Supplemental HHRE used
fish caught from Point Fermin to Redondo Canyon (Fish Survey segments 9,12,13/14,15 and
EPA B) (Figure 2-1). Six fish species were included in the updated HHRE because they
represented a sufficient number of samples to make the assessment statistically valid. The
fish species evaluated represent a mix of water-column and bottom feeders, and pelagic and
local dwelling species: white croaker, kelp bass, surfperch, barred sandbass, and California
scorpionfish. Unlike the LACSD data, which analyzed PCBs as Aroclors, the Fish Survey
analyzed and reported PCBs as congeners. Combining the data increases overall variation
and effect point estimates in the risk and hazard results; however, the Supplemental HHRE
attempted to minimize this effect by estimating risk using minimum, 95 percent UCL, and
maximum concentrations of PCBs for each fish species evaluated.
2.1.2.2 Exposure Assessment
The evaluation of potential human cancer and noncancer risks is based on skin-off-fish-fillet
results. The fish fillet scenario simulates fish consumption rates of all anglers as described
in the Santa Monica Bay Seafood Consumption Study (SMBRP, 1994). To address the potential
for high fish ingestion rates found in some Asian communities and other ethnic groups,
high-end fish consumer scenarios were included in the evaluations. The risk scenario
included RME and CTE scenarios based on all-angler and Asian-angler consumption rates.
RME consumption rates used in the analysis were 107.1 g/day and 115.7 g/day. CTE
consumption rates for all-angler and Asian-anglers were both 21.4 g/day.
2.1.2.3 Risk Characterization
As discussed below, under the RME and CTE conditions (using 95 percent UCLs), DDTs
contributed the most to the total cancer risk for five species, while PCBs contributed the
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
most to cancer risk for one species (rockfish). Under the RME and CTE conditions, PCBs
contributed most to HI values for all six species.
RME Scenario
For both all-angler and Asian-angler consumers under RME consumption of fish fillets,
excess lifetime cancer risks from DDTs and PCBs for three species (white croaker, California
scorpionfish, and barred sandbass) ranged from 3 xlO4 to 7 x 1O3, based on 95 percent UCL
concentrations. Of the six species tested, the highest risk was from white croaker fillets with
a risk of 6 x 1O3. White croaker fish typically contain higher levels of DDTs and PCBs than
other fish from the PV Shelf. This is primarily because white croaker is a nonmigratory fish
that feeds off the ocean floor. Risks from the other three species (kelp bass, rockfish, and
surfperch) ranged from 7 x 10~5 to 1 x 10~4.
As with the HQ (which is for a single chemical), when the HI (Hazard Index) for exposures to
multiple chemicals exceeds 1, the calculated intake exceeds the daily reference dose. The HI
values for all six species were 2 to 198. White croaker fillets also had the highest HI values.
CT Scenario
For both all-angler and Asian-angler consumers under CTE conditions (using 95 percent
UCLs), for consumption of fish fillets, cancer risks from DDTs and PCBs for one species
(white croaker) was 6 x 1O4 based on 95 percent UCL concentrations. Risks from the other
five species ranged from 6 x 1O6 to 3 x 1O5. The HI values from three of the six species
(white croaker, California scorpionfish, and barred sandbass) were 2 to 37. Kelpfish,
rockfish, and surfperch have HI values below 1.
Uncertainties and Limitations
These risk calculations are quantitative estimates of current and future potential cancer risks
and noncancer adverse health hazards. However, these numbers do not predict actual
health outcomes. Using approaches and methodologies based on EPA guidance documents,
the potential cancer risks and health hazards are estimated in a conservative, public health-
protective manner.
The estimation of exposure in the supplemental HHRE requires numerous assumptions
regarding the likelihood of exposure, frequency of ingestion of contaminated fish, the
concentration of contaminants in fish and the period of exposure. Another main
assumption of the exposure assessment is that the period of constituent intake is assumed to
be constant and representative of the exposed population. Assumptions used in the
supplemental HHRE tend to simplify and conservatively approximate actual conditions,
thereby serving to maximize confidence in decision-making.
The following uncertainties should be considered when interpreting the results for the
supplemental HHRE:
• Fish Sampling and Laboratory Analysis. Uncertainty associated with fish sampling and
laboratory tissue analysis includes representativeness of the fish samples collected,
sampling errors, the variable nature of fish exposures to DDTs and PCBs from the PV
Shelf, and the inherent variability (standard error) in the laboratory analyses.
• DDTs and PCBs in Fish Fillet (Muscle). Human health risks were evaluated using DDTs
and PCBs. Although other contaminants are present in PV Shelf sediments and fish
tissue, potential risks from exposure to or consumption of DDTs and PCBs are of
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2. RISK ASSESSMENTS AND MODELING
LOS ANGELES
COUNTY
Palos Verdes Peninsula
^ - Catch Ban Sampling Location
/~~\ - LACSD Fish Sampling Zone
n 2\- EPA/MSRP Fish Survey Segment
FIGURE 2-1
EPA, MSRP and LACSD 2002
Fish Sampling Locations
ES042007001SCO/FS CHART 2.DOC/071550021
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
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2. RISK ASSESSMENTS AND MODELING
• greatest concern. Therefore, the evaluation focused on these compounds. Exclusion
of other chemicals detected in PV Shelf fish tissue could result in a significant
underestimation of cumulative risk, but only in the event that the other chemicals
bioaccumulated, were of high toxicity, were present in high enough concentrations in
the fish fillet of fish typically caught by recreational and commercial fishers, and were
typically eaten by fish consumers.
• Method of Fish Preparation. No attempt was made in the study to quantitatively
evaluate the effects of fish preparation methods on human health risks, which could
result in an under- or overestimation of risk. Contaminant burdens in fish could
decrease by 10 to 70 percent depending on how the fish is prepared and cooked (EPA,
1993b). Conversely, the risk analysis used only contaminant concentrations found in
fish tissue (i.e., skin off fish fillets). DDT and PCBs concentrations in whole fish are 8
to 10 times higher. Therefore, the risk assessment underestimates risk to populations
that consume whole fish.
• Fish Consumption Rates. The Guidance for Assessing Chemical Contaminant Data for Use in
Fish Advisories (EPA, 2000) provides a mean total fish consumption rate for the general
population of 17.5 g/day for the general population recreational anglers in the United
States. This rate includes fish that are caught both recreationally and commercially,
and meals that are eaten at home and away from home. The median consumption
rate used in the supplemental HHRE, 21.4 g/day, is based on 338 boat anglers who
reported consuming fish in the previous 4 weeks (28 days) in the Santa Monica Bay
Seafood Consumption Study (SMBRP, 1994). The RME rates of 107.1 and 115.7 g/day
represent the upper 90 percent consumption rates, respectively, for all anglers and
Asian anglers, from the same study.
2.2 2002/2004 Coastal Marine Fish Contaminants Survey
The levels of DDTs and PCBs vary among fish species and locations along the Southern
California Bight and even in the PV Shelf Study Area. The most contaminated fish found in
the region is the white croaker, a fish found in soft-bottom habitats (Allen et al. 1996). This
fish feeds on worms, crustaceans, and other organisms living in the contaminated bottom
sediments. White croaker is a mainstay of anglers fishing from piers, jetties, and small boats
along the Southern California coast (Allen et al. 1996). Fishing statistics show that it is the
third most commonly caught fish in Los Angeles County, with a high consumption rate
relative to catch rate.
Fish that forage in reef habitats, such as kelp bass and some surfperch, reside in the
contaminated area but do not feed on prey living in bottom sediments. In previous studies
they were generally found to be less contaminated than white croaker; however, in certain
locations sampled in the 1987 OEHHA survey, these species had high enough levels of
DDTs and PCBs that the State included them in the fish consumption advisories (Pollock et
al., 1991).
Pelagic fish, such as Pacific chub mackerel and Pacific bonito, do not reside full time in the
contaminated area and do not feed on mud-dwelling organisms. Previous studies found
that concentrations of DDTs and PCBs in pelagic species generally were low, and no such
species were included in the State consumption advisories for southern California coastal
waters. However, these previous analyses were generally limited to DDTs and PCBs; little
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
data existing on the levels of mercury and other potential contaminants of concern across all
the species targeted by subsistence and sport fishers.
2.2.1 Survey Design
The EPA and the Natural Resource Trustees jointly sponsored a multi-purpose survey of
contaminants in marine fish along the Southern California Coast between Ventura and Dana
Point. The objectives of the study were:
• Generate reliable information on contaminants of concern in fish caught by
subsistence and sport fishers in the study area;
• Provide data to support the State's assessment of the existing commercial catch ban
zone for white croaker in the vicinity of the Palos Verdes Shelf;
• Identify suitable locations for artificial reef project to restore lost fishing services to
the public; and
• Support EPA's PV Shelf Superfund site remediation program.
With the assistance of a scientific review board (SRB), in 2002 the Trustees and EPA
designed and implemented an extensive fish sampling and analysis program to address
these objectives. The SRB included nearly two dozen public- and private-sector individuals
with expertise specific to the Southern California coastal areas and experience in key
technical areas necessary for the development of the plan. Overall, the Trustees and EPA
implemented a plan that collected 2,676 fish, including individuals from 30 locations
between Ventura and Dana Point (Figure 2-2), representing 23 different species.
Locations and species were targeted for collection based on several factors relevant to
project objectives, including current fish advisories in Southern California, available data on
recreational and subsistence fishing, historical fish contamination data, and considerations
regarding artificial reef implementation. Most fish were collected between August and
November 2002. White croaker were collected in the vicinity of the commercial catch ban in
2002, 2003, and 2004. Not all collected fish were analyzed; in some cases initial rounds of
testing eliminated the need for further testing of certain species-location combination.
The laboratory analysis included five contaminants of potential concern: DDTs, PCBs,
mercury, chlordane, and dieldrin. The rationale for analyzing for non-Palos Verdes Shelf
related contaminants was to address the possibility that fish might have high levels of other
contaminants that could affect restoration decision-making and/or management of the
fishery. Factors in the contaminant selection process included bioaccumulation, persistence,
and regional detection history.
For most organochlorine contaminant analysis, i.e., PCBs, DDTs, chlordane, and dieldrin,
contaminant levels were measured for each individual fish, with a sample size of ten fish
per species-location combination. Transient pelagic species, e.g., Pacific chub mackerel,
Pacific sardine, Pacific barracuda, expected to have lower, more uniform contaminant levels
relative to resident species, as well as a few other species, were analyzed as composites,
generally of ten fish. For mercury analysis, all species were initially analyzed as 10-fish
composites due to expected lower variability within a species. Where composite results
indicated that spatial differences in mercury concentrations might be significant within a
species, individual fish were subsequently analyzed for mercury.
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2. RISK ASSESSMENTS AND MODELING
D.
B
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a a
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a
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2. RISK ASSESSMENTS AND MODELING
2.2.2 Summary of Data
Overall, concentrations of PCBs, DDTs, and chlordane varied broadly throughout the
species and segments. In contrast, very few fish had detectable concentrations of dieldrin.
Concentration data discussed below are expressed as mean concentrations for a given
species and segment, which includes up to ten fish. For each contaminant, the range and
distribution of mean concentrations are based on a log-normal distribution of mean
concentrations, divided into quartile ranges (the "lower range", up to the 25th percentile; the
"interquartile range" from the 25th to the 75th percentile; and the "higher range" above the
75th percentile). The designation of "higher" and "lower" indicate the relative contaminant
levels in groups of fish.
DDTs
For DDTs, the lowest mean concentration was found in opaleye from King Harbor (segment
7, 0.9 ppb) and the highest mean concentration in white croaker from the ocean side of the
Los Angeles breakwater near Cabrillo Pier (segment 15, 3180 ppb). The interquartile range
of the species/segments was roughly between 60 and 200 ppb. Species most commonly
found in the higher quartile range for DDTs included white croaker, kelp bass, California
scorpionfish, and barred sandbass. Species that were consistently below the 75th percentile
included black croaker, California corbina, California halibut, jacksmelt, Pacific barracuda,
Pacific chub mackerel, queenfish, shovelnose guitarfish, surfperch, white seabass, and
yellowfin croaker.
PCBs
Mean concentration of total PCBs varied broadly among species and locations, but less so
that DDTs. The lowest mean PCB concentration was found in opaleye from the Seal Beach
area (segment 19, 3.06 ppb), while the highest mean PCB concentration was found in white
croaker from the ocean side of Cabrillo Pier (segment 15, 347 ppb). The inter-quartile range
for mean PCB concentrations was roughly between 20 and 70 ppb. No species had mean
PCB concentrations consistently above the inter-quartile range throughout the area. Species
that were consistently below the 75th percentile were black croaker, California corbina,
California halibut, California sheephead, jacksmelt, Pacific barracuda, Pacific chub
mackerel, queenfish, rockfish, shovelnose guitarfish, water-column-feeding surfperch, white
seabass, and yellowfin croaker.
Chlordane
The mean concentration of chlordane also varied broadly among species and locations.
Jacksmelt from inside the Los Angeles breakwater at Cabrillo Pier (segment 16, 0.18 ppb)
had the lowest mean concentration, while the highest mean concentrations were found in
white croaker from Santa Monica Bay (segment 5, 71 ppb). The inter-quartile range for
mean chlordane concentrations was 4.27 to 11.2 ppb. This range represented most species
and segments.
Summary for Organochlorines
With few exceptions, the spatial and interspecies variability in organochlorine
concentrations found in this survey were largely consistent with those from previous
surveys. White croaker was generally found to be the most highly contaminated species.
Fish caught in locations closest to the Palos Verdes Shelf, i.e., southern Santa Monica Bay,
Palos Verdes Shelf, San Pedro Bay, tended to have higher contaminant levels than those
caught further north or south, i.e., Ventura County or Orange County. Variation in
MAY09/MAY09PVS FS CHART 2.DOC/ 2-13
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
organochlorine concentrations did not follow a clear pattern of higher concentrations in fish
that occupy higher trophic levels or larger sizes.
In most cases, DDT concentrations were higher than PCB concentrations, particularly close
to the Palos Verdes Shelf. This DDT/PCB ratio is consistent with the reported sediment
concentrations of DDTs and PCBs, which have approximately a 10 to 1 ratio in the
sediments (LACSD, 2006). Opaleye were an exception to this general trend, and were
consistently found to have higher PCB concentrations than DDTs. The PCB concentrations
in opaleye were similar to those of other reef/surf zone fish species, but opaleye DDT
concentrations were much lower. While opaleye is the only herbivore among the species
analyzed, it is not clear if this explains the lower DDT concentrations.
Mercury
Mean concentrations of mercury were lowest in Pacific sardine from inside the Los Angeles
Breakwater at Cabrillo Pier (segment 16,18.6 ppb) and highest in black croaker from inside
the Los Angeles breakwater (commercial catch ban segment A, 582 ppb). Interestingly,
while black croaker mean organochlorine concentrations were at or below averages found in
other species, black croaker had the three highest mean mercury concentrations. The inter-
quartile range (based on log-normal distribution) for average mercury concentrations was
roughly 75 to 180 ppb. Overall, mean concentrations of mercury above the interquartile
range were found in 11 species (barred sandbass, kelp bass, black croaker, California
scorpionfish, Pacific barracuda, sargo, California halibut, rockfish, shovelnose guitarfish,
white croaker, and white seabass). Ten of the species with mean mercury concentrations in
the higher range did not have any samples that were in the lower range, suggesting a more
species-dependent pattern for mercury than was found for the organochlorines. Species
that were consistently either "intermediate" or "lower" in mean mercury concentrations
were benthic-feeding surfperch, California corbina, California sheephead, jacksmelt,
opaleye, Pacific chub mackerel, queenfish, topsmelt, water-column feeding surfperch, and
yellowfin croaker. Variation in mercury concentrations among the fish collected in this
survey appears to be driven by differences between species and fish size, as has been
generally found in other surveys. No consistent hot spots for mercury were identified.
Larger, higher trophic level species (kelp bass, barred sandbass) were generally higher in
mercury concentrations than smaller, lower trophic level species. Pacific chub mackerel had
some of the lowest mercury concentrations of all the species analyzed.
Whole Fish Analysis
In addition to the skin-off fillet data described above, multiple body components were
analyzed for a subset of kelp bass and white croaker. These results enabled the estimation
of quantitative relationships between contaminant concentrations in the different body
components, as well as the total contaminant levels in whole, ungutted fish. These
relationships may be specific to particular species and locations, as well as to specific
contaminant types and levels, e.g., organic contaminants, which may be higher in lipid-rich
tissues, and mercury, which may be higher in muscle-rich tissues. An analysis of covariance
was used to quantify relationships between contaminant levels (PCBs, DDTs) in three body
components (skin-on fillets, viscera, and "remainder") and skin-off fillets. The effect of
species (kelp bass, white croaker) on these relationships also was investigated.
All of the body component concentrations were significantly correlated with the fillet
concentrations, with higher fillet concentrations associated with higher component
concentrations. In most cases, the relationship between fillet concentration and the
2-14 /MAY09PVS FS CHART 2.DOC
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2. RISK ASSESSMENTS AND MODELING
concentration in other body parts was not significantly affected by species. Skin-on fillets
had the lowest increase in PCB and DDT concentrations compared to skin-off fillets,
averaging approximately 6 to 7 times the DDTs and PCBs found in associated skin-off fillets.
Viscera and "remainder" samples had similar, but greater, increases in PCB and DDT
concentrations compared to skin-off fillets, averaging approximately 11 to 17 times the
DDTs and PCBs found in associated skin-off fillets, depending on contaminant and
component.
Component concentration data also were used to develop equations that estimate the PCB
or DDT concentration in a whole, ungutted fish based on the concentration in a skin-off
fillet. First, equations were developed to estimate the PCB or DDT concentration in the
three additional body components (skin-on fillets, viscera, and "remainder") of a fish based
on its fillet concentration. These concentrations, in combination with estimated component
proportions (based on the laboratory weight of each of the four components) were then
summed to estimate concentrations in a whole, ungutted fish. The results suggest that
whole fish have concentrations of PCBs and DDTs that are generally 8 to 10 times higher
than the fillet concentrations.
2.2.3 LACSD vs. Fish Survey Comparison
The Ocean Fish Survey and the 2002 LACSD annual monitoring program collected kelp bass
and white croaker from comparable locations on Palos Verdes Shelf (Figure 2-1). Fish
survey segment 13-14 is similar to LACSD's Zone 1, segment 12 is similar to LACSD's Zone
2, and segment 9 is similar to LACSD's Zone 3. Combined, these collections allowed for a
comparison of two collections of kelp bass from segment 13-14 to collections from LACSD's
Zones 2 and 3. This analysis revealed no significant effects of body size or location among
the four collections (segments 13-14, Zones 1, 2, 3) for either DDTs or PCBs. Kelp bass from
the region encompassing southern Santa Monica Bay to San Pedro Bay outside the Los
Angeles breakwater had similar concentrations of PCBs and lower, but comparable,
concentrations of DDTs.
For white croaker, concentrations of DDTs and PCBs were an order of magnitude lower
than those from comparable locations in the 2002 LACSD survey conducted on the PV shelf.
The difference in contaminant results between LACSD's Zone 1 collection in 2002 and the
fish surveys segment 13-14 is particularly striking, given the proximity of the two stations
(Figure 2-3). Various potential drivers for this pattern were explored: (1) interlaboratory
variability in contaminant results; (2) seasonal differences in contaminant concentrations;
(3) general size differences in collected fish; and (4) small-scale differences in habitat and/or
location.
The first three explanations were eliminated based on the study of interlaboratory
variability and the timing and size of the fish collected in the two studies. Differences
between the two laboratories, while potentially responsible for a two-fold difference in
concentration results, could not explain the orders-of-magnitude difference between LACSD
Zone 1 and segment 13-14. Both collections were made within a month of each other in fall
2002, so it is unlikely that timing drove the differences in contaminant results between the
two collections. White croaker collected from LACSD Zone 1 were significantly smaller
than those collected from segment 13-14. However, in order for this size difference to drive
contaminant values, an inverse relationship between size and contamination level in the fish
is necessary. No statistically significant inverse relationship between organochlorine
MAY09/MAY09PVS FS CHART 2.DOC/ 2-15
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
concentrations and size was found for white croaker, so it is unlikely that size differences
are the source of the differences in PCB and DDT concentrations.
The LACSD Zone 1 and segment 13-14 collections have two key differences in microhabitat:
separation by depth differential and by a hard substrate. The LACSD Zone 1 collection was
made from deeper water than the segment 13-14 collection (47 m versus 25 m). Sediment in
the deeper areas in the PV Shelf have higher organochlorine concentration than the shallow
areas (LACSD 2006). Thus, if particular white croaker spent the majority of its time in either
deep or shallow water, the shallow-water associated individuals would tend to have lower
concentrations of organochlorines than the deep-water-associated individuals. Second, the
two collections were made in different areas relative to the JWPCP White Point outfalls. The
LACSD Zone 1 collection was located near the pilot capping cells, west of the outfall pipes,
where higher sediment concentrations of PCBs and DDTs exist. The segment 13-14
collection was made inshore and on the east side of the outfalls, away from the effluent-
affected sediment deposit, where sediment concentrations are much lower (LACSD, 2006).
White croaker will actively avoid hard substrates under some conditions (Allen, 2001), so
the outfall pipes may act as a barrier to along-shore movement of white croaker.
To test for differences between fish collected at different depths and sides of the outflow
pipes, LACSD conducted a revised sampling survey in 2005. This survey collected ten
white croaker from the traditional Zone 1 location, ten white croaker from the west side of
the outfalls in 25 meters of water, and ten white croaker on the east side of the outfalls in 25
meters of water, close to where the original segment 13-14 white croaker were collected
(Figure 2-4). LACSD captured and filleted these fish using the same protocol used in the
fish survey. These 30 white croaker were analyzed for DDTs and PCBs at the LACSD
laboratory.
The concentrations of PCBs and DDTs in the white croaker collected off of White Point in
2005 by LACSD were consistent with the hypothesis that the more highly contaminated fish
reside on the west side of the outfalls. Although concentrations of PCBs and DDTs were
greater in the deeper location, the difference between deep and shallow locations west of the
outfalls was not significant. However, the concentrations of DDTs and PCBs on the east
side of the outfalls were significantly lower than either location west side of the outfalls, and
matched the concentrations found in white croaker in segment 13/14 in 2002. The results
from LACSD's 2005 sampling suggest differences between the east and west sides of the
outfalls, and raises questions regarding home ranges and feeding patterns of white croaker.
LACSD Fish Contaminant Trend Data
The difference in contaminant concentrations between white croaker caught on PV Shelf for
the EPA/MSRP survey and by LACSD in 2002 was striking. The 2005 comparison found
concentrations in white croaker east of the outfalls were similar to the concentrations
measured in 2002. While the contaminant concentrations were higher west of the outfalls,
the LACSD white croaker Zone 1 catch in 2005 had contaminant concentrations an order of
magnitude lower than in 2002: average DDT concentration 33,740 ppb in 2002 vs. 3,850 ppb
in 2005. Table 2-1 shows LACSD fish trend data since 1999. DDT concentrations in Zone 1
white croaker are the lowest recorded by LACSD. However, as the table shows, vacillations
in concentrations are not uncommon.
2-16 /MAY09PVS FS CHART 2.DOC
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2. RISK ASSESSMENTS AND MODELING
•o
g
1«
P
M
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fa*
ill
*l
|J
ii
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Figure 2-3 from EPA/MSRP Contaminant Fish Survey (June 2007)
MAY09/MAY09PVS FS CHART 2.DOC/
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
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2. RISK ASSESSMENTS AND MODELING
Figure 2-4 Palos Verdes white croaker contaminant bioaccumulation sampling locations for 2005
33-5Q1
33°45'
ZONE 3
Palos Verdes
Peninsula
60m
33°40'
B-A-«
»m
ZONE 2
:
San Pedro
Sea Valley
118°25'
118-201
Zone 1 - Royal Palms (White Point) to Bunker Point.
Zone 2 - Long Point to Point Vicente.
Zone 3 - Palos Verdes Point to Bluff Cove.
MAY09/MAY09PVS FS CHART 2.DOC/
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
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2. RISK ASSESSMENTS AND MODELING
Table. 2.1 Trend in White Croaker Contaminant Concentrations ( g/kg), LACSD Data
Year
1999
2001
2002
2004
2005
2006a
Zone I
DDTs
26,410
25,390
33,740
10,820
3,850
3,880
PCBs
1,600
1,880
2,950
1,190
400
440
Zone 2
DDTs
6,010
5,450
8,610
7,050
NA
2,740
PCBs
680
540
880
920
NA
350
Zone 3
DDTs
4,250
2,510
1,470
1,610
NA
1,550
PCBs
20
140
30
80
NA
190
a In 2006, LACSD's analysis changed from Aroclors to PCB congeners and from single fish to composites from each zone.
2.3 Ecological Risk Assessment
An Ecological Risk Assessment (EcoRA) was conducted for the PV Shelf site in 2003
(CH2M HiU, 2003). The EcoRA corresponds to the baseline EcoRA as described in EPA
guidance, Ecological Risk Assessment Guidance for Superfund Sites: Process for Designing and
Conducting Ecological Risk Assessments (EPA, 1997), and a Validation Assessment as
described by DISC guidance, Guidance for Ecological Risk Assessment at Hazardous Waste
Sites and Permitted Facilities (DISC, 1996).
2.3.1 Purpose and Scope of the Ecological Risk Assessment
The EcoRA was prepared in 2003 to evaluate ecological risk through identification and
characterization of existing concentrations of contaminants at the site, and potentially
complete exposure pathways to ecological receptors. The EcoRA summarized data
collected throughout the Southern California Bight (SCB) with an emphasis on the PV Shelf
site, from as many different sources as was practical, for the period of 1990 to 2002 (birds
were summarized for 1985 to 2000). The EcoRA relied on work completed for the Natural
Resource Damage Assessment, including a Food Web/Pathways Study (HydroQual, Inc.,
1994). The EcoRA described the risk from DDTs and PCBs to marine biota that inhabit or
may use the PV Shelf site and the SCB. These biota include benthic invertebrates, benthic
and water-column fish, brown pelicans, double-crested cormorants, bald eagles, peregrine
falcons, and sea lions and their pups. This assemblage of receptors represents the marine
food web from contaminated sediments up through invertebrate and vertebrate prey to
wide-ranging, higher order consumers.
2.3.1.1 Exposure Assessment
Exposure to contaminants of potential ecological concern (COPECs) was evaluated in
multiple ways, depending on the receptor and available data. Internal exposure, in the
form of measured and estimated concentrations of COPECs in tissues, was considered for
invertebrates, fish, birds, and mammals. External exposure, defined as contact with
COPECs in environmental media (sediment and water), was considered for biota directly
exposed to the media in which they live, such as benthic invertebrates and fish. In addition
to measured and estimated internal and external exposures, a food exposure model for
birds and marine mammals was used to estimate the daily dosages of COPECs from diet.
The model required knowledge of dietary composition, ingestion rates, and foraging ranges
MAY09/MAY09PVS FS CHART 2.DOC/
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
as compared to the modeled geographic distribution of fish contamination. The bird and
sea lion exposure model was based on the establishment of regression relationships
between COPEC concentrations in sediment and fish tissues at locations throughout the
SCB. The sediment-to-fish regressions were then used to estimate potential concentrations
of COPECs in fish tissue for any SCB location. Overlapping concentrations in a mixed
dietary fish assemblage within their foraging range yielded an estimated daily dosage of
COPECs for the bird and sea lion receptors. Peregrine falcon exposure estimates required
the additional step of estimating tissue concentrations in their seabird diet (as derived from
estimated fish concentrations in the seabird diet). Bald eagle exposure required a
combination of exposure through dietary fish as well as sea lion carcasses and seabirds
(with tissue concentrations, in turn, as estimated from their fish diets). Sea lion pup
exposures were estimated from maternal milk, as estimated from maternal dietary
exposure and the use of literature-derived equations for transfer of contaminants to milk.
The food web model concluded that the SCB did not exceed DDT screening values for
marine mammals but did exceed screening values for birds and fish. PCBs exceeded
screening values for sea lion pups and double-crested cormorants, and to a lesser extent
brown pelicans and peregrine falcons, but not fish.
2.3.1.2 Food Web Exposure Model Update
The food web model discussed in the 2003 EcoRA incorporated data for the period of 1990
to 2001. In 2006, the food web model was updated with more recent sediment and fish
data from 2001 to 2005, i.e, LACSD sediment core data (2001 and 2003) and fish tissue
data (2004 and 2005), and MSRP/EPA fish tissue data (2002). The updated food web
model lacked data to credibly model COC uptake beyond the local, bottom-feeding fish of
PV Shelf. Collaboration with the Natural Resource Trustees on data collection and analysis
is necessary to update existing food web models of the Southern California Bight.
Recently, the SCCWRP completed a study of COCs in pelagic fish that form the principle
diet of piscivorous birds and sea lions (Jarvis et al., 2007). Although concentrations of
DDTs and PCBs have dropped dramatically since the 1980s (see Table 2-2), DDT
concentrations continue to exceed risk screening values for northern anchovy, Pacific
sardine, and Pacific chub mackerel throughout the SCB. Virtually none of the fish sampled
exceeded wildlife risk screening values for PCBs. Another recent study of pinnipeds
(Blasius and Goodmanlowe, 2008) found concentrations of DDTs and PCBs in California
sea lions to have dropped over the 12-year period of the study (1994 to 2006). However,
concentrations of DDTs and PCBs in California sea lions and Pacific harbor seals continue
to be among the highest values reported worldwide for marine mammals.
2.3.2 Bioaccumulation Modeling
The FS uses a food web model developed by HydroQual (rev!997) for the Natural
Resources Damage Assessment (NRDA) to develop relationships between concentrations
of DDTs and PCBs in sediment and in white croaker. HydroQual's bioaccumulation
model was developed to determine whether the sediment of the PV Shelf constituted the
dominant source of the DDE and PCBs found in local fish. The model consisted of
mechanistic equations for bioenergetics and toxicokinetics that were parameterized using a
combination of literature-derived and site-specific data. The similarity of the field-
measured and model-calculated fish tissue concentrations supported the contention that
the sediment of the shelf constituted the dominant source of DDE and PCBs to white
2-22 /MAY09PVS FS CHART 2.DOC
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2. RISK ASSESSMENTS AND MODELING
Table 2-2: Comparison of total DDT and total PCBs measured in pelagic forage fishes and squid of the Southern
California Bight in the early 1980s and 2003-2004 (Southern California Costal Water Research Project 2007 Annual
Report - Chlorinated hydrocarbons in pelagic forage fishes and squid of Southern California Bight, Jarvis et al.)
Species/ Location
Year
Composite
Type
Total DDT
(|o.g/mg wet wt)
Total PCBs
(|j,g/mg wet wt)
California market squid
Coastal
SCB
Northern anchovy
Coastal
LA/LB Harbor
SCB
Pacific chub mackerel
Coastal
Santa Monica Bay
Palos Verdes
Laguna Beach
SCB
Pacific Sardine
Coastal
SCB
1 980-81 a
2003-04"
1980-81 *
1980C
2003-04"
1980-81 a
1981d
1981 d
1981 d
2003-04"
1 980-81 a
2003-04"
Mantle
Whole
Muscle
Muscle
Whole
Muscle
Muscle
Muscle
Muscle
Whole
Muscle
Whole
Mean
3 10.0
28 0.8
SD
10.0
1.2
Mean
10.0
0.0
SD
9.0
0.1
5 47.0
5 121.0
24 60.6
33.0
31.0
38.3
8.0
98.0
3.1
9.0
21.0
5.1
6
5
5
1
13
130.0
57.0
44.0
129.0
41.4
145.0
37.0
_
86.0
40.2
26.0
15.0
12.0
34.0
2.3
22.0
7.0
12.0
22.0
3.1
5
34
484.0
34.1
112.0
28.7
105.0
1.6
40.0
2.5
aSchaeferetal. 1982
b Jarvis etal. 2007
c Mearns and Young 1980
dGossetetal. 1983
croaker. The same model framework was extended to include birds and mammals as part
of the NRDA and, as stated above, formed the basis for the exposure assessment for birds
and mammals in the Ecological Risk Assessment for PV Shelf (CH2M Hill, 2003). The
model is included in Appendix C along with a memorandum showing the calculations
used to apply the model to current PV Shelf conditions. The bioaccumulation model
provides estimates of white croaker/sediment relationships for COCs with fish tissue
concentrations expressed on a lipid basis (mg/kg lipid) and sediment concentrations on an
organic carbon basis (mg/kg organic carbon). The relationships were converted from lipid-
normalized fish tissue concentrations to wet weight-based contaminant concentrations in
skin-off fillets (mg/kg wet weight) by multiplying the model relationships by an estimate
of the average lipid content of skin-off fillets of white croaker.
MAY09/MAY09PVS FS CHART 2.DOC/
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
Fish tissue concentrations of 490 ppb DDT and 80 ppb PCBs represent a 1 x 10'5 risk for the
recreational angler consumption rate of 21.4 g/day (i.e., central tendency exposure). The
carbon-normalized sediment concentration that achieves these values in white croaker is 28
mg/kg organic carbon (OC) DDT and 8 mg/kg OC PCBs in sediment. A comparable 1 x
10'5 risk using RME consumption rates (i.e., 116 g/day) would be 2.3 mg/kg OC DDT and
0.7 mg/kg OC PCBs in sediment. It is unclear whether these sediment concentrations are
achievable since they are near or below background. In the interim, a less stringent 1 x 1Q-4
risk is proposed for the RME value, which translates to fish tissue concentrations of 400 ppb
DDTs and 70 ppb PCBs. Sediment goals associated with the 1 x 10'4 risk using RME
consumptions rates would be 23 mg/kg OC DDT and 7 mg/kg OC PCBs.
The model correlates lipid content in fish to carbon-normalized sediment data. The model
used lipid values from the 2002/2004 Coastal Marine Fish Contaminants Survey
discussed in section 2.2. The survey measured a range of lipid concentrations in white
croaker; the fish analyzed from PV Shelf (segment 13/14) did not have the highest lipid
content. The bioaccumulation model provides a correlation between contaminant
concentrations in sediment and white croaker that would need further refinement to
accurately predict contaminant levels in fish. EPA and NOAA are planning a white croaker
tracking study to learn more about white croaker feeding patterns on PV Shelf that will
allow EPA to refine the biota to sediment relationship. Data from the white croaker tracking
study will contribute to the development of the final remediation plan.
2.4 Predictive Model of Natural Recovery
As part of the Natural Resource Damage Assessment of the Palos Verdes margin, the U.S.
Geological Survey (USGS) and its co-investigators were asked to provide a quantitative
prediction of the fate of the effluent-affected (EA) sediment deposit and associated
contaminants, DDTs and PCBs, that had accumulated on the Palos Verdes Shelf and slope.
The research specifically addressed the question of the fate of the contaminated sediment
under natural recovery conditions. The expert report (Drake et al., 1994), produced in 1994,
used data collected in 1992 and earlier. A supplement to the report was issued in 1996
(Sherwood et al., 1996) using additional sediment data from 1991 and 1993. In 2000, the
USGS revisited natural recovery predictions using new data to further refine the predictive
model developed in 1994 (Sherwood et al., 2002). These reports are included as appendix B.
The reports concluded that the majority of the buried EA deposit north of the outfalls would
most likely stay buried. Episodic events, primarily winter storms, would winnow out
surface contamination associated with fine, effluent-affected sediment and bring in
uncontaminated sediment, causing contaminant concentrations to drop in the short-term,
i.e., the next ten years. The model indicated surface concentrations most likely would
increase temporarily near the outfalls as sediment sources lapsed. However, surface
contaminant concentrations would drop again below 1 mg/kg as new, uncontaminated
material is added to the system.
Data collected from 1995 through 2005 have confirmed the predictive value of the model
and have provided additional material to further refine the model. The following sections
discuss the natural recovery model and more recent studies.
2.4.1 Summary of the 1994 Predictive Modeling of Natural Recovery
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2. RISK ASSESSMENTS AND MODELING
Data collected in the early 1990s for the Natural Resource Damage Assessment as well as
available background information were used to develop and calibrate a one-dimensional
numerical model of resuspension and transport of sediment in the near-bottom waters of
the shelf, and a one-dimensional model of contaminant profiles in the bed. These models
provided a mechanism to predict rates of natural recovery. The models used two LACSD
monitoring sites, 3C and 6C, as representative of the EA sediment deposit far field and near
field to the source, i.e., White Point outfalls (see Figure 2-5). Both of these sites are on the
60-m isobath and have long records of measurements of p,p'-DDE (hereinafter referred to as
DDE) concentrations and other properties in the EA sediment deposit. Sediment cores from
these two sites provided an important time-series that yielded reliable information on
changes in sedimentation rates and contaminant profiles for the period 1970 to 1991.
2.4.1.1 Model of Processes Affecting Inventory and Distribution of DDE
The model identified the following factors as those that influence the ultimate fate of the
reservoir of DDT and PCBs in the effluent-affected sediment:
1. burial or erosion caused by either wave/current or gravity-induced sediment
transport and/or variation in sediment supply;
2. biological activities that cause solid-phase mixing of the bed sediment and
associated contaminants, and changes in particle characteristics;
3. resuspension of contaminated sediment and subsequent loss of contaminant to
overlying water via desorption;
4. in situ desorption of contaminant to porewater in the bed, followed by molecular
diffusion to the overlying sea water, and/or loss through bed irrigation processes;
5. contaminant losses or gains due to biological or chemical degradation or
transformation; and
6. biological uptake of contaminants and removal (via migration or predation).
At the time of the 1994 report, DDT and PCBs were considered resistant to degradation by
natural biological and chemical processes (Moore and Ramamoorthy, 1984), therefore,
contaminant losses via those mechanisms were not considered. Neither was loss via
biological uptake considered in the report. The processes that were factored into the model
are discussed below.
Sediment Erosion and Deposition
The rate of sediment accumulation or erosion at a given location on the shelf was an
important input parameter for the model. Rapid burial of the historical DDT- and PCB-
contaminated sediment beneath a thick layer of clean sediment would isolate the
contaminant, whereas sediment erosion would lead to increased surface concentrations,
either through direct physical exposure or via increased biodiffusive flux, at least until the
contaminated layer eroded completely. Sedimentation rate is determined by the balance
between sediment supply and the capacity of currents to transport and disperse the
sediment that is delivered. Whereas it is generally believed that the capacity of waves and
currents to transport sediment varies little over decades on the PV Shelf, the supply of
sediment particles to the shelf from the two major sources, the JWPCP outfalls and the
Portuguese Bend landslide (PEL), has varied markedly over time.
In the mid-1950s, the supply of sediment to the PV Shelf increased approximately an order
of magnitude above natural background rates owing to erosion from the PEL at the
MAY09/MAY09PVS FS CHART 2.DOC/ 2-25
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
northwest end of the shelf and the discharge of particulates by JWPCP diffusers at the
southeast end of the shelf. Sedimentation rates reflected these large new local sources,
reaching values as high as 2 cm/yr at 6C and about 1 cm/yr at 3C in the 1970s (Drake,
1994). However, the high sedimentation rates observed in the 1970s and 1960s on the outer
shelf were not sustained in the 1980s, despite a substantial increase in the rate of sliding of
the PEL. Sedimentation rates on the outer shelf, i.e., at 3C and 6C, declined to less than 50
percent of previous values. This decrease is correlated with the reduced discharges of
particulates from the JWPCP diffusers in the late 1970s and 1980s. Strong control of
sedimentation rate by the diffuser system was especially apparent at the nearfield site 6C.
USGS studies (Kayen, 1994) indicate that a portion of that the PEL sediment resides on the
inner and middle parts of the shelf (<60 m depths) and is being gradually reworked by
waves and currents and transferred to deeper water and downstream areas to the
northwest. This sediment will continue to supply particles to outer shelf and slope sites at
relatively high rates, compared with estimated pre-effluent and pre-PBL rates, for some
years. Figure 2-6 contrasts the sediment bed of the northwest area of the Shelf to the
southeast area.
Bioturbation
Typically, a large number of animals live on or within the seabed on continental shelves,
and their normal activities cause bed mixing, which strongly affects the preservation of
strata and the distribution of particles and associated chemical compounds within the
seabed. The impacts of these activities fall into two broad categories, bed mixing through
bioturbation and alterations of the sediment properties, e.g., bulk density and particle size
distribution changes. Normal activities of the benthic organisms include locomotion over
and within the seabed, burrow excavation, tube building and deposit feeding, i.e., ingestion
of particles and assimilation of organic compounds. Figure 2-7 shows small organisms
typical of those that inhabit the shelf floor—brittle stars and sea urchins.
Many of the organisms displace particles in all directions within the bed, resulting in a
diffusive bioturbation that is usually most intense in a near-surface layer but that can
extend, at much reduced rates, tens of centimeters into the bed. If concentration gradients of
particle-associated materials exist in the bed within the zone of biodiffusion, the mixing will
cause a flux of that material, i.e., a net transport, upward or downward depending on the
direction of the gradient. The effluent-affected sediment deposit on the PV margin contains
a buried horizon of DDT- and PCB-rich sediment, and therefore biodiffusive mixing tends
to transport more contaminant upward, resulting in a net gain of contaminant in the
surficial sediment.
Rates of solid-phase biodiffusion in the surface layer (5-10 cm depth) were measured at shelf
sites from the JWPCP diffusers to the Redondo shelf using Thorium 234 (234Th) profiles in
sediment cores collected in 1992 and 1993 by Wheatcroft and Martin (1996). Their data
demonstrate considerable variation in bioturbation rate along the 60-m isobath.
Biodiffusivity values ranged from 1 to 89 cm2/yr, with most values in the 5 to 25 cm2/yr
range (Wheatcroft and Martin, 1996). Low to moderate mixing rates occurred near the
diffusers, and substantially larger mixing rates occurred to the northwest, where the benthic
communities are known to be more balanced and less influenced by the current JWPCP
discharges. These data were used to determine the biodiffusion coefficients in the
numerical model.
2-26 /MAY09PVS FS CHART 2.DOC
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2. RISK ASSESSMENTS AND MODELING
118J26'W
r~ -i
- 33M6TJ
•1C
• 2C
Figure 2-5: Palos Verdes Shelf, LACSD stations along 60 m isobath (USGS, 2002)
MAY09/MAY09PVS FS CHART 2.DOC/
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
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2. RISK ASSESSMENTS AND MODELING
1
i
-=
1
48
S.3
3>s
o 'i
•a a
.a d
II
I!
MAY09/MAY09PVS FS CHART 2.DOC/
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
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2. RISK ASSESSMENTS AND MODELING
Molecular Diffusion
The measured concentrations of DDE in the bed sediment and calculated concentrations in
porewater on the PV Shelf greatly exceed concentrations in the water above the bed, and
this gradient will drive DDE from the bed by molecular diffusion. Loss due to molecular
diffusion depends on the nature of the thin water layer immediately above the sediment-
water interface, the aqueous solution diffusivity of the dissolved compound, and the
porosity of the bed (Chen, 1993). The molecular diffusion coefficient is similar in magnitude
to bioturbation coefficients and constitutes an important mechanism for release of organic
chemicals from the bed. Molecular loss for the effluent-affected sediment at 6C is estimated
using the model of Chen (1993) developed for analysis of the release of hydrophobic species
from the sediment of Boston Harbor. The calculated magnitude of the loss term is
approximately the same as that for loss due to resuspension and desorption during storm
events, and is included in the predictive model.
2.4.1.2 Numerical Model of Processes
Numerical values or equations were developed to represent the key processes: sediment
deposition or erosion, bed mixing through biodiffusion, and loss of contaminants from the
sediment through resuspension and sorption during storm events or through molecular
diffusion to the ocean water above the sea bed. Terms in the equation equate temporal
changes in the contaminant profile at a specific depth with changes caused by biodiffusion
and molecular diffusion in porewater, sedimentation, and loss due to degradation,
resuspension and desorption or decay.
The model was initialized using profiles of DDE measured in 1989 cores from sites 3C and
6C and was tested in various ways to confirm that it was correctly implemented and that it
provided correct results when used to model evolution of the EA sediment deposit during
the years for which good data coverage was provided. The model results compared
favorably with historical data.
2.4.2 1996 Supplement to the Expert Report
The numerical model was updated in 1996 using new data from 1991 and 1993. These data
were used to revise the estimate of historical burial velocities, revise and supplement the
time series of DDE inventories, initialize model runs, and for a comparison with previous
model results.
Revised burial velocities were estimated from DDE profile data between 1981 and 1991 at
Site 3C and between 1983 and 1993 at Site 6C, and were assumed to continue through 2003,
when full secondary treatment of wastewater at the JWPCP was expected to be
implemented. These burial velocities were 0.44 cm/yr at Site 3C and 0.47 cm/yr at Site 6C
and included contributions from redistribution of existing bottom sediments, natural
background sedimentation, PEL material and JWPCP emissions. Expected future
background rate, (i.e., the natural background supply, estimated as 0.1 cm/yr) to provide
estimates of the future burial velocity associated with all sources of sediment supply.
The report acknowledged that timing of the burial velocity scenarios was uncertain.
However, the most likely scenarios assumed that no changes would occur until 2003, when
full secondary treatment would be implemented at the JWPCP. The scenarios assumed that
MAY09/MAY09PVS FS CHART 2.DOC/ 2-33
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
the burial velocity would quickly (by 2010) reach the future burial velocity of 0.32 cm/yr for
Site 3C and -0.61 cm/yr for Site 6C. After 2010, redistribution of sediment would steadily
reduce the contribution of flux divergence until, in 2025, the only contributions would be
from the PEL, JWPCP emissions, and natural sources.
Long-term equilibrium sedimentation rate for Site 3C was calculated to be 0.13 cm/yr,
slightly less than half of the historical rate. Bounds on this rate, estimated by propagating
uncertainties through the calculations, ranged from 0.02 to 0.22 cm/yr. At site 6C, the burial
velocity associated with future sediment supplies was calculated to be 0.21 cm/yr, 45
percent of the historical rate, with a range of 0.06 to 0.33 cm/yr. These rates would continue
indefinitely under model runs that extended to 2100. These calculations indicated that
sediment supply at both sites would decrease significantly; however, sedimentation rates
would remain depositional.
At Site 6C, this rate included erosion that would be caused by divergence in the alongshelf
sediment-transport rate associated with alongshore changes in sediment size. Near the
southeast end of the EA deposit, fine sediment would be transported away (alongshelf
toward the northwest) more quickly than they could be replaced by the coarser, pre-effluent
sediment. If not offset by accumulation of sediment from the outfalls, PEL, or natural
background supply, this would result in erosion. Removal of the finer material and
armoring of the deposit would eventually reduce the alongshore gradients in grain size, and
long-term equilibrium would be established. In the absence of any sediment supply, final
equilibrium would require that fine sediment be removed until armoring produces a 10-cm
thick surface layer with grain-size characteristics that match pre-effluent sediment. This
would amount to about 50 percent by volume of the existing fine sediment, and would
require erosion of 10 cm of material, which would take until about 2035, depending on the
burial-velocity scenarios (Sherwood 1994). The burial velocity scenarios presented in the
report assumed that the input of background sediment supply and cross-shelf transport
would reduce the time to final equilibrium, so the most likely scenarios assumed final
equilibrium would occur in 2025.
Model results for the most likely scenario at Site 3C indicated that concentration of DDE in
surface sediment will fall steadily, reaching 1 mg/kg in 2009 and decreasing to less than 0.02
mg/kg at the end of the model simulation in 2100. Model results for the maximum
deposition scenario predicted that surface concentrations would fall below 1 mg/kg even
earlier (2006); maximum erosion scenario predicted surface concentrations would fall more
slowly, reaching 1 mg/kg in 2025, and a final value of 0.1 mg/kg in 2100.
Model results for the most likely scenario at Site 6C predicted that concentrations of DDE at
the surface would decrease from the 1991 maximum of 11.4 mg/kg to slightly more than 1
mg/kg in 2008, then rise to about 2 mg/kg in 2019 as erosion brings the subsurface
maximum into the zone of biodiffusivity. After that, surface concentrations would fall
gradually, reaching 1 mg/kg in 2044 and 0.1 mg/kg in 2100. Results for the maximum
deposition scenario predicted a steady decrease in surface concentrations, reaching 1 mg/kg
in 2012 and <0.05 mg/kg in 2100. Results for the maximum erosion scenario showed an
initial drop in surface concentration until 2003, after which it would increase to a peak value
of 39.4 mg/kg in 2018. Surface concentration would then fall, reaching 1 mg/kg in 2064 and
a final value of 0.2 mg/kg in 2100.
2-34 /MAY09PVS FS CHART 2.DOC
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2. RISK ASSESSMENTS AND MODELING
The predictive model was developed before JWPCP implemented full secondary treatment
of wastewater. The most recent measurement of sediment cores at 3C and 6C occurred in
2005. The median surface concentration of DDE at 3C was 1.26 mg/kg and at 6C 1.36
mg/kg, both in agreement with the USGS model's most likely scenario. Figures 2-8 and 2-9
show longterm trends in sediment cores collected and analyzed by LACSD for DDE.
Additional data collected through 2005 have been used to refine predictions of the fate of
DDE in the EA sediment on PV Shelf.
2.4.3 Ongoing Refinements of the Predictive Model
Sherwood et al. (2002) continued to refine the model using field measurements, laboratory
analyses, and calculations to set parameters for the model. Analyses of available data,
including measurements made every two years from 1981 to 1997 by the LACSD, suggest
that the two sites northwest of the White Point outfalls, 3C and 6C, will remain depositional,
even as particulate supply from the sewage-treatment plant and nearby PEL decreases. At
these sites, model predictions for 1991-2050 indicate that most of the existing inventory of
DDE will remain buried and that surface concentrations will gradually decrease. Analyses
of data southeast of the outfalls suggest that erosion is likely to occur in the southeast edge
of the existing effluent-affected deposit. Model predictions for this area show that erosion
and biodiffusion will re-introduce the DDE to the upper layer of sediment, with subsequent
increases in surface concentrations and loss to the overlying water column. Figure 2-10
shows DDE profiles for the sediment deposit across the 60-m isobath. The 2000 model also
recognized that some of the EA sediment deposit, i.e., at 3C, had DDE converting into
DDMU.
USGS is presently engaged in updating the predictive model using data collected since full
secondary treatment was instituted at the JWPCP. The predictive model focused on DDE as
the dominant contaminant on the shelf. Historical investigations found that PCBs were
collocated with DDE, but at approximately one-tenth the concentration. Therefore, it was
assumed that loss rates could be applied equally to both contaminants. Data from 2005
confirmed that DDE is undergoing reductive dechlorination but PCBs are not. New model
parameters added transformation rates for DDE along with loss estimates; however, PCB-
specific model runs were not performed.
Another potentially significant factor that had been identified but not measured is
compaction of the sediment deposit. The initial model did not consider compaction in
calculating burial velocity. Recent data show bulk density has been increasing over time,
i.e., sediment has been compacting, and the changes are on the order of 15 to 20 percent in
the top 15 cm of sediment. Bulk density increases with distance from the outfalls to the
northwest. Areas that were considered potentially erosive, because the area of peak
contaminant concentration appeared to be shifting upward toward the surface, are
depositional when corrected for compaction. Similarly, sedimentation rates can be
underestimated if not corrected for compaction.
Based on the DDE loss calculations, sediment concentrations will fall below 1 mg/kg except
for the outfall area in approximately 10 years (2018). The exception is the outfall area.
Median PCB concentration in sediment across the PV Shelf Study Area was 0.2 mg/kg in
2004. Inshore and southeast of the outfalls PCB concentrations were below detection limits.
MAY09/MAY09PVS FS CHART 2.DOC/ 2-35
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
Nearer to the outfalls and on the shelf slope PCB concentrations approach or exceed 1
mg/kg.
2.4.4 Ambient Water Quality Forecasting
In order to compare alternatives in the feasibility study, estimates of future contaminant
concentrations in water as well as biota and sediment are necessary. The length of time
required for PV Shelf to reach EPA's ambient water quality criteria (AWQC) for human
health and ecological receptors depends on sediment mixing rates, DDE loss rates within
the EA deposit as well as through mass flux to the overlying water. USGS performed
preliminary calculations using simple transfer models to estimate PV Shelf water quality
changes over time. These calculations are included in Appendix B.
The first model estimated DDE concentrations in surface sediment on the PV shelf and mass
fluxes of DDE from sediment to overlying water. It assumes no erosion or deposition. The
second model used the estimate of mass flux of DDE as a loading term, and calculated
dilution of DDE in PV Shelf water, exchange with SCB water, and ultimate loss to the North
Pacific Ocean.
The models assume PV Shelf water is rapidly exchanged with surrounding SCB water. The
resident time for PV Shelf water is about one day. The SCB water is exchanged more
slowly, but its residence time is also short, about 78 days. Water quality in the SCB
responds very quickly to changes in loading from contaminated sediment. Rough
calculations of flushing time for the water column over the PV Shelf suggest a half-life of a
few days or less. The flushing time for water closer to the sediment is slower. Transfer rates
from sediment to overlying water were inferred from the apparent loss rates in surface
sediment.
The sediment box model requires estimates of biodiffusive mixing, in-situ transformation
rate from DDE to DDMU, and transfer rate from sediment to the overlying water column.
Estimates of future water quality are sensitive to these variables. Depending on mass flux
rate from sediment to overlying water, PV Shelf water reaches EPA's AWQC for DDT for
protection of human health in water in 30 to 60 years.
Table 2.3 Summary of box model parameters and results, 150-year model simulation.
Case Pi p2 Kz
(yr1) and
fc
(yn)
1 0.07 0.03 5 0.2 0.003 0.6 85 2024 2053 2037 2065
3 0.03 0.01 5 5 0.2 1.6 96 2070 >2150 2067 2136
4 0.07 0.01 0.5 13 0.03 0.7 97 2027 2052 2039 2065
Model assumes initial DDE inventory is 84 metric tons. Depending on loss rates and sediment to water
transfer rate, ambient water quality criteria of 0.22 ng/L is reached in 2037 to 2067.
Final
Inventory
(metric
tons)
Final
Surf.
Cone.
mg/kg
Mean
Surf.
Cone.
mg/kg
Mean
Flux to
Water
kg/yr
Year
Surf. <1
mg/kg
Year
Surf.
<200
Hg/kg
Year
PV
Shelf
Water
<0.22
Year
PV
Bottom
Water
<0.22
2-36 /MAY09PVS FS CHART 2.DOC
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2. RISK ASSESSMENTS AND MODELING
Figure 2-8: DDE Trend at Station 3C (LACSD, 2005)
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
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2-38 /MAY09PVS FS CHART 2.DOC
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2. RISK ASSESSMENTS AND MODELING
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2-40 /MAY09PVS FS CHART 2.DOC
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2. RISK ASSESSMENTS AND MODELING
Figure 2-10: Peak DDE in LACSD cores along 60 m isobath (Sherwood, 2006)
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
This page intentionally blank
2-42 /MAY09PVS FS CHART 2.DOC
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2. RISK ASSESSMENTS AND MODELING
As discussed above, PCB loss rates have not been calculated. Water column data from 1997
(Zeng, 1999) included measurements of PCBs one meter above the sediment bed plus a
number of measurements at other depths, up to 35 meters above the bed. While the sample
taken at 35 meters met the AWQC of 0.064 ng/L, the samples closer to the bed ranged from
0.2 ng/L to 1 ng/L. In general, PCB concentrations were higher in summer than in winter.
In summer of 2003 (Zeng, 2004) sampled water 2 meters above the bed over the EA
sediment deposit for 42 PCB congeners. Of these, 7 congeners were detected, totaling 0.556
ng/L PCBs. This is half of the quantity detected at the same location and depth in 1997, i.e.,
1.11 ng/L. These two sampling events are insufficient to predict when the PCB AWQC for
human health of 0.064 ng/L would be reached; however, it does indicate concentrations are
dropping.
MAY09/MAY09PVS FS CHART 2.DOC/ 2-43
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2. RISK ASSESSMENTS AND PREDICTIVE MODELING
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3.0 Remedial Action Objectives and
Development of Remediation Goals
This section on remediation goals defines several key cleanup concepts common to all
feasibility studies prepared in accordance with CERCLA rules and guidance:
• Remedial action objectives (RAOs);
• Applicable or relevant and appropriate requirements (ARARs) and regulatory
guidance that is "to be considered" (TBC) in the development of remedial
alternatives.
Collectively, these concepts set the stage for developing effective and protective remedial
alternatives for the PV Shelf Feasibility Study.
RAOs are general remedial objectives developed to be protective of human health and the
environment. RAOs for PV Shelf are designed to address the threats site contaminants pose
to human and ecological receptors, as discussed in Section 2.0.
ARARs and TBCs constitute the body of existing statutes, regulations, ordinances, guidance,
and published reports pertaining to all aspects of a potential remedial action for the site.
This information typically influences the development of remedial alternatives by
establishing numeric remediation goals, operating parameters, monitoring requirements,
etc. The alternatives developed in Section 5.0 must, to the extent practicable, attain
compliance with all ARARs and address the recommendations of TBCs.
3.1 Development of Remedial Action Objectives
The subsections below summarize the risk assessments and ARAR evaluation used to
develop the RAOs for this FS.
3.1.1 Media and Chemicals of Concern
Defining the media and chemicals of concern (COCs) on the PV Shelf is a necessary
prerequisite to developing site-specific RAOs. Per Agency guidance, RAOs should specify
the relevant COCs, the exposure route(s) to receptors by media (e.g., surface water, soil, or
sediments), and an acceptable contaminant level for each exposure route. See Guidance for
Conducting Remedial Investigations and Feasibility Studies under CERCLA, Interim Final
(1988a), pp. 4-7, 4-15. ARARs and TBC information are generally identified with reference
to media and COCs. For example, identifying surface water as a medium of concern
triggers consideration of federal clean water regulations.
3.1.1.1 Media of Concern
The RI identified surface water and sediment as the media of concern. Contamination of
these media poses risks to human health and ecological receptors. The risk assessments
(Section 2.0) determined that addressing sediment contamination will have the greatest
impact on improving surface water quality, and thus on reducing risks to humans and
/MAY09 CHAPT3.DOCMAY09 3-1
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3. REMEDIAL ACTION OBJECTIVES AND REMEDIATION GOALS
wildlife. Remedial actions presented in Section 4.0 describe general cleanup options for
COCs contained in sediment only. Cleanup of surface water and reductions in fish tissue
COC concentrations will occur naturally once the source of contamination to surface water
and biota is removed, treated, or contained.
3.1.1.2 Chemicals of Concern
Investigations of PV Shelf identified various metals and organic compounds associated with
industrial and municipal waste. However, the contaminants found to pose the greatest
threat to human health and the environment are DDTs and PCBs.
3.1.2 Risk Assessments
Pursuant to CERCLA, the risk assessments conducted in support of the RI (CH2M HILL,
2007) evaluate potential threats to human health and the environment from the chemicals of
concern at the PV Shelf Study Area. A summary of the risk assessments can be found in
Section 2.0 of this FS.
The general EPA remediation objective for Superfund sites is to reach an acceptable level of
risk, rather than to achieve specific concentration levels (USEPA, 1990). In the National
Contingency Plan (NCP), EPA defines the acceptable level of excess lifetime cancer risk
(ELCR) as ranging from 1 x 10'6 to 1 x 1Q-4 (USEPA, 1990). For noncarcinogenic effects, EPA
uses a Hazard Index (HI) approach, based on reference dose exposures. An HI exceedance
(HI > 1), represents an exposure exceeding reference dose levels. The RAOs presented
below are based on this guidance from EPA.
3.1.2.1 Protection of Human Health
EPA has developed screening values for common contaminants found in fish (EPA, 2000c).
The concentrations are based on a consumption rate of 17.5 g/day, 70 kg body weight and,
for carcinogens, a 10~5 risk level over a 70-year lifetime.
Table 3-1 : Recommended Screening Values for Recreational Fishers, target analyte in M9/kg (ppb)
Total DDT (sum of 4,4'- and 2,4'- isomers of DDT, DDE, and ODD)
Total PCBs (sum of congeners or Aroclors)
Noncarcinogen
screening value
2,000
80
Carcinogen screening
value (10-5 risk level)
117
20
EPA guidance recommends using these values when site-specific data are not available. As
described in Section 2.0, the human health risk assessments used the Santa Monica Bay
Seafood Consumption Study (SMBRP, 1994) to develop reasonable maximum exposure (RME)
and central tendency exposure (CTE) scenarios to calculate potential risk. Based on angler
consumption patterns, the updated human health risk evaluation (HHRE) technical
memorandum prepared for the remedial investigation report (CH2M Hill, 2007) used a
recreational angler consumption rate of 21.4 g/day for the CTE scenario and 115.7 g/day for
the high-end consumption rate, or RME. These consumption rates represent the 90th
percentile and mean consumption rates for all fish consumed, as reported in the study. In
order to provide an additional layer of protectiveness, the HHRE tech memo assigns these
consumption rates to one species instead of the multiple species anglers identified
3-2
/MAY09 CHAPT3.DOC/
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3. REMEDIAL ACTION OBJECTIVES AND REMEDIATION GOALS
consuming in the study. Using these criteria, the following fish tissue concentrations were
determined to be protective.
Table 3-2: Protectiveness levels based on local fish consumption rates
Single species consumption rate
Based on 21 .4 g/day
Based on 116 g/day
DDTs in fish fillet
490 |jg/kg (ppb)
400 jjg/kg (ppb)
PCBs in fish fillet
80 pg/kg (ppb)
70 pg/kg (ppb)
ELCR*
1 x10'D
1x1Q-4
* Excess lifetime cancer risk, i.e., incremental increase in the probability of developing cancer during one's lifetime in addition to
the background probability.
3.1.2.2 Protection of Ecological Receptors
As described in Section 2.0, several lines of evidence, including sediment and porewater
hazard quotients (HQs), benthic community effects, toxicity tests, effects on fish, and
modeling of food chain transfer to birds and mammals, were used to evaluate ecological
risk at the PV Shelf. The results show that the highest risks are in the vicinity of the PV Shelf
outfalls. Intermediate-risk areas are found generally to the north and northwest of the
outfalls. Finally, low-risk areas occur south of the outfalls, in shallower waters (<30 m), at
the far northern areas of the PV Shelf, and throughout the remainder of the Southern
California Bight (SCB), which is the area of the coastal Pacific Ocean between Point
Conception and San Diego, including the Channel Islands (Lee, 1994).
Ecological receptors on PV Shelf include the following: invertebrates that live in the
sediment; fish, including fish that consume the invertebrates; piscivorous birds; and
mammals. Marine mammals and birds have little to no direct contact with the
contaminated sediment on PV Shelf. Part of their body burden of DDT and PCBs can be
attributed indirectly to consumption of PV Shelf-dwelling fish, and food web models that
estimate trophic transfer of contaminants up the food chain have been developed (Glaser
and Connolly, 2002, CH2M Hill, 2003). However, these models contain considerable
uncertainty and are not useful in establishing contaminant-specific remediation goals for
sediment. Ecological receptors that are affected directly by PV Shelf sediment are benthic
invertebrates and local fish species.
Sediment effects concentrations (SEC) protective of benthic invertebrates were developed
from a study of sediment quality of the SCB. MacDonald (1994) conducted an exhaustive
review of laboratory and field investigations related to the biological effects of DDTs and
PCBs to benthic macroinvertebrates exposed to sediment from the SCB. Using a tiered
strategy and a weight-of-evidence approach, he established SEC thresholds for DDT, DDE,
DDD, Aroclor 1254 and PCBs. Exceedance of the SEC would indicate that effects, e.g.,
reduced survival and reproduction, on sensitive species are likely to occur. Field data were
used only if no information from controlled laboratory studies (i.e., spiked sediment
bioassays using arthropods) with dose-response findings were available to determine SECs.
The study determined that DDT concentrations of 2.0 mg/kg in sediment with 1 percent
total organic carbon (TOC) and 0.577 mg/kg PCBs at 1 percent TOC were protective of
benthic infauna. Sediment concentrations for the PV Shelf Study Area are below these SEC
values for PCBs and only the immediate area around the outfall exceeds the DDT SEC.
MAY09/MAY09 CHAPT3.DOC/ 3-3
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3. REMEDIAL ACTION OBJECTIVES AND REMEDIATION GOALS
Fish-eating birds and mammals accumulate contaminants through food chain transfer;
therefore, their risk relates to the contaminant concentrations in fish rather than in sediment.
Literature-derived screening values for COCs in fish as food for piscivorous wildlife vary
widely. The most protective benchmark for DDT is from Environment Canada, 14 |o,g/kg DDT
(CCME 1999). Environment Canada does not list a benchmark for total PCBs; however, the
British Columbia Ministry of the Environment uses 100 Mg/kg as its screening value
(BCMOELP 1998). As discussed in Section 2.3.1.2, COC concentrations in pelagic forage fishes
in the Southern California Bight exceed the DDT benchmark of 14 ng/kg but not the PCBs
benchmark (Table 2.2). The 2007 study found regional differences, with the fish closer to PV
Shelf generally containing the most COCs.
3.2 Applicable or Relevant and Appropriate Requirements
Potentially applicable or relevant and appropriate requirements (ARARs) are identified and
reviewed during development of remedial actions to ensure that remedial actions comply
with applicable laws and regulations. Compliance with ARARs may have a significant
effect on the cost and implementability of a particular alternative during the initial action
and long-term operation.
3.2.1 ARARs Overview
Section 121(d) of CERCLA states that remedial actions on CERCLA sites must attain
(or justify the waiver of) any federal or more stringent state environmental standards,
requirements, criteria, or limitations that are determined to be ARARs. Applicable
requirements are those cleanup standards, criteria, or limitations promulgated under federal
or state law that specifically address the situation at a CERCLA site. A requirement is
applicable if the specific terms, or "jurisdictional prerequisites," of the law or regulation
directly address circumstances at the site.
If a requirement is not legally applicable, the requirement is evaluated to determine whether
it is relevant and appropriate. Relevant and appropriate requirements are those cleanup
standards, standards of control, and other substantive environmental protection
requirements, criteria, or limitations promulgated under federal or state law that, while not
applicable, address problems or situations sufficiently similar to the circumstances of the
proposed response action and are well suited to the conditions of the site. The criteria for
determining relevance and appropriateness are listed in Title 40, Code of Federal
Regulations (CFR), Section 300.400(g)(2).
ARARs are concerned only with substantive, not administrative, requirements of a statute
or regulation. The substantive portions of the regulation are those requirements that pertain
directly to actions or conditions in the environment. Examples of substantive requirements
include quantitative health- or risk-based restrictions upon exposure to types of hazardous
substances.
Administrative requirements are the mechanisms that facilitate implementation of the
substantive requirements. Administrative requirements include issuance of permits,
documentation, reporting, record keeping, and enforcement. Thus, in determining the
extent to which onsite CERCLA response actions must comply with environmental laws, a
distinction should be made between substantive requirements, which may be ARARs, and
administrative requirements, which are not. According to Section 121 (e) of CERCLA, a
3-4 /MAY09 CHAPT3.DOC/
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3. REMEDIAL ACTION OBJECTIVES AND REMEDIATION GOALS
remedial response action that takes place entirely onsite may proceed without obtaining
permits. This permit exemption applies to all administrative requirements and permits.
Pursuant to EPA guidance, ARARs generally are classified into three categories: chemical-
specific, location-specific, and action-specific requirements. These categories were
developed to help identify ARARs, although some do not fall precisely into one group or
another. The ARAR categories are defined as follows:
• Chemical-specific ARARs include those laws and requirements that regulate the release
to the environment of materials possessing certain chemical or physical characteristics or
containing specified chemical compounds. These requirements generally set health- or
risk-based concentration limits or discharge limitations for specific hazardous
substances. If, in a specific situation, a chemical is subject to more than one discharge or
exposure limit, the more stringent of the requirements should generally be applied.
• Location-specific ARARs are those requirements that relate to the geographical or
physical position of the site, rather than the nature of the contaminants or the proposed
site remedial actions. These requirements may limit the placement of remedial action
and may impose additional constraints on the cleanup action. For example, location-
specific ARARs may refer to activities in the vicinity of wetlands, endangered species
habitat, or areas of historical or cultural significance.
• Action-specific ARARs are requirements that apply to specific actions that may be
associated with site remediation. Action-specific ARARs often define acceptable
handling, treatment, and disposal procedures for hazardous substances. These
requirements are triggered by the particular remedial activities that are selected to
accomplish a remedy. Examples of action-specific ARARs include requirements
applicable to groundwater treatment, effluent discharge, hazardous waste disposal,
and emissions of air pollutants.
The response action alternatives will be evaluated in terms of compliance with the ARARs
identified above as part of the effectiveness analysis.
3.2.2 Chemical-Specific ARARs
Surface Water
Chemical-specific ARARs for surface water consist of EPA's ambient water quality criteria
(AWQC) for DDTs and PCBs. These criteria, which have been developed for the protection
of both aquatic life and human health, are summarized in Table 3-4.
Section 304 of the Clean Water Act requires EPA to publish criteria for water quality.
33 United States Code (U.S.C.) Section 1314(a). The EPA AWQC for DDTs and PCBs were
originally published in October 1980 (USEPA, 1980a; USEPA, 1980b). The human health
values have been updated since the original criteria were published in 1980 to reflect revised
consumption rates and carcinogenic potency values from EPA's Integrated Risk Information
System (IRIS) database. 40 CFR §131.36 and 57 Federal Register (FR) 60848, December 22,
1992.
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3. REMEDIAL ACTION OBJECTIVES AND REMEDIATION GOALS
Table 3-3:
Chemical
DDTs
PCBs
EPA Ambient Water Quality Criteria
Saltwater Aquatic Life,
24-Hour Average (ng/L)
1a
30
Human Health
0.22b
0.064
(ng/L)
a The sum of the 4,4'- and 2,4'- isomers of DDT, ODD, and DDE.
b For DDE and ODD, the AWQC for protection of human health are 0.59 and 0.83 ng/L, respectively.
ng/L - nanograms per liter
DDTs
Criteria for the protection of saltwater aquatic life are, for most contaminants and pollutants,
based on toxic effects data for water-column organisms. However, for DDTs, which
bioaccumulate to high levels and may cause toxicity to organisms at higher trophic levels,
EPA determined that more restrictive criteria were necessary to protect fish-eating birds and
birds feeding at higher trophic levels, including birds that feed on other birds and scavenge
on the carcasses of marine mammals. The chronic marine aquatic life criterion for DDT is 1
ng/L, which is equivalent to 1O9 grams per liter (g/L) (USEPA, 1980a). This criterion is set
to achieve a fish tissue (whole-body) DDT concentration of 150 Mg/kg (wet weight) in prey,
and is based on a 1975 study of California brown pelicans in the SCB (Anderson et al. 1977).
The EPA AWQC for the protection of human health from DDT exposure through water and
consumption of DDT residues that have bioaccumulated in fish is 0.22 ng/L, and is based
on a bioconcentration factor (BCF) of 53,600. The BCF relates the concentration of a
chemical in aquatic animals to the concentration in the water in which they live. The steady-
state BCFs for a lipid-soluble compound, such as DDT, in the tissues of various aquatic
animals seem to be proportional to the percent lipid in the tissue. The AWQC is based on a
DDT concentration in fish tissue of approximately 12 |o,g/kg and would result in a lifetime
excess cancer risk of up to 1 x 10-6, assuming a consumption rate of approximately one meal
per month. See 45 FR 79331, updated to reflect current IRIS potency factors. 40 CFR §131.36,
57 FR 60848.
PCBs
The EPA chronic marine aquatic life criterion for PCBs of 30 ng/L is also fish residue-based.
It was set at the level that would be protective of sensitive aquatic species and result in
achievement of the Food and Drug Administration (FDA) tolerance level (for protection of
human health) of 5,000 (ig/kg in fish after bioaccumulation (USEPA, 1980b). There is no
evidence that acute or chronic toxicity to aquatic life will occur at levels of PCBs less than 30
ng/L; thus, the marine aquatic life criterion has not been revised.
The EPA AWQC for the protection of human health from the bioaccumulation of PCBs in
fish is 0.064 ng/L, based on achieving a concentration of 1.4 (ig/kg in fish consumed, which
would result in a lifetime excess cancer risk of up to 1 x 10~6, assuming a consumption rate
of one meal per month (USEPA, 1996).
Section 121(d)(2)(A) of CERCLA requires that remedial actions meet federal AWQC
established under Section 304 or 303 of the Clean Water Act, where such AWQC are
determined by EPA to be relevant and appropriate to remedial actions at the site. 42 U.S.C.
§9621(d)(2)(A) and 40 CFR §300.430(e)(2)(I)(E). In evaluating whether specific AWQC are
relevant and appropriate to remedial actions at a Superfund site, CERCLA requires EPA to
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3. REMEDIAL ACTION OBJECTIVES AND REMEDIATION GOALS
consider four criteria: (1) the uses of the receiving water body; (2) the media affected; (3) the
purposes of the criteria; and (4) current information. 42 U.S.C. § 9621(d)(2)(B)(i); see also
USEPA (1990).
EPA guidance to determine if AWQC are relevant and appropriate to remedial action at a
Superfund site provides that:
A water quality criteria component for aquatic life may be relevant and
appropriate when there are environmental factors that are being
considered at a site, such as protection of aquatic organisms. With
respect to the use of water quality criteria for the protection of human
health, levels are provided for exposure both from drinking the water and
from consuming aquatic organisms (primarily fish) and from fish
consumption alone. Whether a water quality criterion is appropriate
depends on the likely routes of exposure (EPA, 1988b).
The AWQC for DDTs and PCBs are relevant and appropriate ARARs that would establish
response action goals at this site since aquatic organisms, wildlife, and humans may be
exposed to these contaminants either directly or through consumption of contaminated
organisms. As stated above, the marine chronic AWQC for DDTs was based on the results
of studies of reproductive impacts to the California brown pelican in the SCB.
The beneficial uses designated by the State of California for coastal waters, which are
discussed below, include fishing, wildlife habitat, preservation of rare and endangered
species, fish migration, fish spawning, and shellfish harvesting. EPA's AWQC were
specifically developed to protect beneficial uses such as these.
Sediment
There are no chemical-specific ARARs for the remediation of PV Shelf Study Area sediment.
Fish
There are no chemical-specific ARARs for the concentration of DDTs and PCBs in fish.
3.2.3 Location-Specific ARARs
Endangered Species Act
The goal of the Endangered Species Act of 1973,16 U.S.C. Section 1531 et seq. is the
conservation and recovery of species of fish, wildlife, and plants that are threatened with
extinction. EPA has consulted with the U.S. Fish and Wildlife Service and the National
Marine Fisheries Service to identify threatened and endangered species and ensure that any
response action is not likely to jeopardize listed species or adversely modify critical habitat.
Because of the presence of endangered/threatened species on the PV Shelf, the substantive
requirements at Sections 7 and 9 of the Endangered Species Act may be applicable. 16 U.S.C.
§§1536 & 1538,
California Endangered Species Act
The goal of the California Endangered Species Act, Section 2050 of the California Fish and
Game Code, is to conserve, protect, restore, and enhance any endangered or threatened
species and its habitat. Regarding the birds likely to nest or feed in the area, most of those
that are listed as endangered or threatened by the state are also listed federally. Because of
the presence of endangered/threatened species on the PV Shelf, the substantive
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3. REMEDIAL ACTION OBJECTIVES AND REMEDIATION GOALS
requirements of the California Endangered Species Act, Section 2080 of the California Fish
and Game Code, may be applicable.
Coastal Zone Management Act
Section 307(c)(l) of the Coastal Zone Management Act (CZMA) requires that federal
agencies conducting or supporting activities affecting land and water resources of the
coastal zone do so in a manner that is consistent with approved state coastal zone
management programs. The remedial alternatives being considered for the PV Shelf Study
Area would affect the resources of the coastal zone. While onsite activities are not subject to
CZMA administrative review or permitting processes, the selected remedy must ultimately
be consistent with the substantive requirements of the coastal zone management plan that
are applicable. 40 CFR §§300.5, 300.430(f)(l)(ii)(B).
The approved coastal zone management program for California coastal waters includes the
California Coastal Act, and is administered by the California Coastal Commission.
Generally, filling of surface waters is allowable only when public benefits exceed public
detriment from the loss of water areas, the filling is for a water-oriented use, and no
alternative upland location is available.
Section 404 of the Clean Water Act and Section 10 of the Rivers and Harbors Act
Section 404 of the Clean Water Act and Section 10 of the Rivers and Harbors Act regulate the
placement of fill in waters of the United States. 33 U.S.C. §1344, 33 U.S.C. §401. Substantive,
as opposed to permitting, requirements would be applicable requirements with regard to
the placement of material on the Palos Verdes Shelf for the purpose of constructing a cap.
In particular, the criteria for determining the acceptability of placing fill into the waters of
the United States as promulgated in 40 CFR Part 300 would be applicable to any capping
alternative.
3.2.4 Action-Specific ARARs
A number of ARARs may be triggered by the specific remedial action selected for
implementation at the PV Shelf site. This section describes some of these action-specific
ARARs.
Marine Protection, Research, and Sanctuaries Act of 1972 (MPRSA) and Ocean Dumping
Regulations
The MPRSA, commonly called the Ocean Dumping Act 33 U.S.C. Section 1404 et seq., and
federal ocean dumping regulations 40 CFR Part 220 et seq. regulate the dumping or disposal
of material in the ocean. Ocean disposal of dredged material is administered by EPA and
the United States Army Corps of Engineers (USAGE) in accordance with the MPRSA.
Dredged material must meet substantive federal testing guidelines to be approved for
disposal. 40 CFR Part 227. Sediment containing more than trace amounts of organohalogen
compounds, such as DDTs and PCBs, typically fail to meet the criteria for ocean disposal.
The substantive requirements of the MPRSA and the ocean dumping regulations may be
applicable to the capping alternatives.
Clean Water Act
Section 403 of the Clean Water Act, 33 U.S.C. §1343, and associated regulations at 40 CFR Part
125, Subpart M regulate discharges into marine waters that have the potential to degrade the
marine environment. These provisions prohibit discharges unless limits can be established to
prevent unreasonable degradation or irreparable harm to the marine environment (EPA,
3-8 /MAY09 CHAPT3.DOC/
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3. REMEDIAL ACTION OBJECTIVES AND REMEDIATION GOALS
1988b). The substantive requirements of Section 403 may be applicable for remedial
alternatives that involve dredging, placement or dewatering of sediment.
Other Action-Specific ARARs
Section 28 of Title 14 of California Code of Regulations (CCR) forbids the taking of certain
fish species from California ocean waters. Title 14 Sections 28.05, 28.06 and 28.10 can be
considered action-specific ARARs for remedial alternatives that involve fish sampling in that
these sections forbid by-catch of protected species.
Section 404 of the Clean Water Act, Section 10 of the Rivers and Harbors Act, and
Section 307(c)(l) of the CZMA can be considered action-specific ARARs for remedial
alternatives that involve dredging, ocean dumping, and material placement. These
requirements are discussed briefly under location-specific ARARs.
3.3 To-Be-Considered (TBC) Criteria and Other Potential
Requirements
3.3.1 To-Be-Considered Criteria (TBC)
A requirement may not meet the definition of an ARAR as described above, but still may be
useful in determining whether to take action at a site or to what degree action is necessary.
This can be particularly true when there are no ARARs for a site, action, or contaminant.
Such requirements are called "to-be-considered (TBC) criteria" and are defined at 40 CFR
Section 300.400(g)(3). TBC materials are nonpromulgated advisories or guidance issued by
federal or state governments that are not legally binding. Although TBC criteria do not
have the status of ARARs, they are considered together with ARARs to establish the
required level of cleanup for protection of health or the environment. Once a TBC is
designated in a ROD, it is enforceable to the same extent as an ARAR.
There are a number of TBC criteria (i.e., guidance and recommendations) that are intended to
protect human health and the environment, including fish-eating birds and predators, and
may be used to define response objectives or cleanup goals for the PV Shelf.
Surface Waters
Porter-Cologne Water Quality Control Act, California Ocean Plan, and Fish and Game Code
The State of California adopted water quality objectives for toxic pollutants pursuant to the
requirements of Section 303 of the Clean Water Act and the Porter-Cologne Water Quality
Control Act, 33 U.S.C. Section 1313 and California Water Code, Article 3. The release of
hazardous substances to surface waters is controlled under these statutes and implementing
regulations, as well as the state Fish and Game Code Section 5650. The California Ocean
Plan, adopted in July 1972 and revised most recently in 2005 (SWRCB, 2005), contains water
quality objectives for DDTs and PCBs in surface waters (0.17 ng/L and 0.019 ng/L,
respectively), which serve as the basis for determining requirements for waste discharge to
the ocean. These chemical-specific objectives apply to all coastal waters of California —
including waters off the Palos Verdes Peninsula — out to 3 nautical miles, and are intended
to "ensure the reasonable protection of beneficial uses and the prevention of nuisance."
The California Ocean Plan lists the following beneficial uses of coastal waters, which include
the waters at the site:
• Industrial water supply
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3. REMEDIAL ACTION OBJECTIVES AND REMEDIATION GOALS
• Navigation
• Water contact and noncontact recreation, including aesthetic enjoyment
• Commercial and sport fishing
• Mariculture
• Preservation and enhancement of designated areas of special biological significance
• Rare and endangered species
• Marine habitat
• Fish migration
• Fish spawning
• Shellfish harvesting
Sediment
Unlike contaminants in soil or water, EPA does not have screening values for contaminants
in sediment. Local conditions affect the toxicity and bioavailability of certain contaminants,
particularly hydrophobic chemicals like DDT and PCBs. The State of California is
developing sediment quality guidelines based on multiple lines of evidence; however, these
guidelines have not yet been finalized.
Fish
Human Health
The U.S. Food and Drug Administration (FDA) is responsible for protecting the public
health by assuring the safety, efficacy and security of the nation's food supply. The FDA
has set action levels for DDT and PCBs in seafood: 5,000 (ig/kg DDT (FDA, 1978) and 2,000
(ig/kg PCBs. 21 CFR §109.30(a)(7). However, these levels are not risk-based and would
pose human health risks above EPA's risk range (1 x!0~4 to 1 x 10~6) when applied to site-
specific fish consumption data from the PV Shelf area.
As stated in section 3.1.2.1, this FS uses the updated Human Health Risk Evaluation (HHRE)
Technical Memorandum (CH2M Hill, 2007) prepared for the PV Shelf Superfund Site
Remedial Investigation to calculate fish tissue contaminant concentrations that would be
protective of human health. Currently, contaminant concentrations in white croaker from
the PV Shelf Study Area exceed the human health target levels, both for the average (CTE)
and high-end (RME) consumers. Table 3-4, below, reflects the sediment concentrations that
would achieve CTE and RME targets.
Ecological Receptors
The TBC criteria for the protection of ecological receptors include screening values for fish
and fish-eating wildlife, and site-specific sediment effects concentrations for benthic
invertebrates. As discussed in section 3.1.2.2., either these benchmarks have been met, e.g.,
SECs for benthic invertebrates, or additional studies are required in order to translate the
benchmark into a sediment goal.
Potential Remedial Goals
Remedial actions cannot reduce contaminant concentrations in fish or water directly.
Instead, reductions in fish or water occur after actions are taken to reduce sediment
concentrations.
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3. REMEDIAL ACTION OBJECTIVES AND REMEDIATION GOALS
Table 3-4: Relationship of CoCs in White Croaker to Sediment
DDTs
Sediment Goal
PCBs
Sediment Goal
Fish fillet 21.4 g/day consumption
rate (achieves 10 5 risk)
490 |jg/kg ww
280|jg/kg@1%TOC
80 |jg/kg ww
80 |jg/kg @ 1 % TOC
Fish fillet 116 g/day consumption
rate (achieves 10 4 risk)
400 |jg/kg ww
230 |jg/kg @ 1 % TOC
70 |jg/kg ww
70|jg/kg@1%TOC
COC concentrations in surface sediment vary greatly across the PV Shelf and slope. At the
30 m depth (approximately 100 ft.), PCBs are not detected in the sediment and DDTs are
well below potential remediation goals. Along the 61-m and 152-m isobaths, DDT
concentrations exceed the potential remediation goals while PCBs exceed the goals around
the outfalls and most of the slope.
3.3.2 Other Potential Requirements
The legal requirements discussed below are not identified as ARARs because ARARs can
only be identified for onsite activities. 42 U.S.C. §9621 (d)(2)(A). However, the capping and
dredging options evaluated in this FS contemplate potential offsite dredging of clean
sediment for ocean disposal (i.e., capping) on the PV Shelf, and potential offsite disposal of
contaminated sediment dredged from the PV Shelf. The legal requirements discussed
below would independently apply to and regulate such dredging.
Section 404 of the Clean Water Act and Section 10 of the Rivers and Harbors Act
Section 404 of the Clean Water Act, 33 U.S.C. §1344, and Section 10 of the Rivers and Harbor
Act, 33 U.S.C. §401, regulate dredging and filling (including in situ capping of sediments) in
waters of the United States. USAGE typically issues permits to conduct dredge or fill
activities, and such permits would be required for activities that are conducted in offsite
areas. Elimination of "special aquatic sites" as a result of dredging can trigger requirements
for mitigation of the lost resource as a condition for approval.
Marine Protection, Research, and Sanctuaries Act of 1972 (MPRSA) and Ocean Dumping
Regulations
The MPRSA, commonly called the Ocean Dumping Act, 33 U.S.C. §1404 et seq., and federal
ocean dumping regulations in 40 CFR Part 220 et seq., regulate the dumping of material in
the ocean. Ocean disposal of dredged material is administered by EPA and USAGE in
accordance with MPRSA. Dredged material must meet substantive federal testing
guidelines to be approved for disposal, set forth at 40 CFR Part 227. Sediment containing
more than trace amounts of organohalogen compounds, such as DDTs and PCBs, typically
fail to meet the criteria for ocean disposal.
Resource Conservation and Recovery Act
Disposal of dredged sediment containing RCRA hazardous waste would trigger certain
independently applicable RCRA requirements. Specifically, the RCRA land disposal
restriction set forth at 22 CCR §66268.1(f) prohibits the disposal of hazardous waste to land
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3. REMEDIAL ACTION OBJECTIVES AND REMEDIATION GOALS
unless it is treated in accordance with the standards set forth at 22 CCR, Chapter 18, Articles
4 or 11, or in federal RCRA regulations, if applicable.
3.3.3 Summary of Potential Remediation Goals
Table 3-5 summarizes potential remediation goals that were consulted in establishing
cleanup levels.
Table 3-5 Summary of Potential Remediation Goals
Criteria
Human Health
Water
Fish
DDTsa
0.22 ng/L
5000 ug/kg
490 ug/kg wet
weight in tissue
40 ug/kg wet
weight in tissue
PCBs
0.064 ng/L
2000 ug/kg
80 ug/kg wet
weight in tissue
7 ug/kg wet
weight in tissue
Sediment
EPA AWQC (EPA, 1980a)
FDA Action Level (FDA, 1978), FDA Tolerance
Level [21 CFR Section 109.30(a)(7)]
10"5 cancer risk for CTE ingestion rate of 21.4
g/day based on supplement (CH2M Hill, 2007) to
PV Shelf Human Health Risk Evaluation
(SAIC,1999)
10"5 cancer risk for RME ingestion rate of 1 16
g/day based on supplement (CH2M Hill, 2007) to
PV Shelf Human Health Risk Evaluation
(SAIC,1999)
Ecological Health
Water
Sediment
Fish as prey for
piscivorous
wildlife
Ing/L
2000 ug/kg @
1% TOC
14 ug/kg wet
weight whole
body fish tissue
30 ng/L
577 ug/kg @
1%TOC
100 ug/kg wet
weight whole
body fish tissue
EPA AWQC (EPA, 1980a)
MacDonald (1994) sediment concentrations
protective of benthic invertebrates for SCB
Environment Canada, National Standards and
Guidelines (CCME 1999) and British Columbia
Ministry of Environment, Land and Parks.
Water quality guidelines. (BCMOELP, 1998)
a The sum of the 4,4'- and 2,4'- isomers of DDT, ODD, and DDE
3.4 Remedial Action Objectives
With consideration of the ARARs and TBCs presented in the previous sections, the
following remedial action objects (RAOs) were developed for the PV Shelf site.
3.4.1 Human Health Risks
RAO: Reduce to acceptable levels the risks to human health from ingestion of fish
contaminated with DDTs and PCBs.
The human health risk assessments determined that exposure to DDTs and PCBs through
consumption of fish is the exposure pathway leading to the greatest potential for adverse
human health effects. Reducing COC levels in fish and/or preventing consumption of
contaminated fish are two ways to reduce risk.
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/MAY09 CHAPT3.DOC/
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3. REMEDIAL ACTION OBJECTIVES AND REMEDIATION GOALS
Protective levels in fish were calculated for two ingestion rates: a reasonable maximum
exposure (RME) equivalent to 116 g/day (about six 5-ounce meals a week), and a central
tendency exposure (CTE) equivalent to 21.4 g/day (about one 5-ounce meal a week). As
discussed in section 3.1.2.1, the general EPA remediation objective is to reach an acceptable
level of risk, defined under the NCP as a range of 1 xlO6 to 1 xlO4 excess lifetime cancer
risk, with 1 x 1O6 as the most protective. EPA guidance for assessing chemical contaminant
data for use in fish advisories (USEPA, 2000c) recommends using the 1O5 cancer risk as the
target remediation goal.
• Achieve interim goal of median DDT concentrations in surface sediment of 46
mg/kg OC (half the target concentration) and PCB concentrations of 7 mg/kg OC by
first Five-Year Review.
• Achieve goal of 400 ng/kg DDT, 70 ng/kg PCBs in white croaker. These
concentrations provide levels of protection of 1 x 1Q-4 cancer risk for the RME
scenario and 1 x 10'5 for the CTE scenario.
• Maintain institutional controls program that aims to prevent contaminated fish from
reaching markets and educates anglers on safe fishing practices.
3.4.2 Ecological Risks
RAO: Reduce to acceptable levels the risks from DDTs and PCBs to the ecological
community (i.e., benthic invertebrates and fish) at the PV Shelf.
The Natural Resource Trustees through the Montrose Settlements Restoration Program
(MSRP) are actively involved in restoring wildlife harmed by DDTs and PCBs. Programs to
enhance fish habitat and restore sea birds and bald eagles are well underway. EPA can
contribute to these efforts by its remedial actions on PV Shelf. Although PCB concentrations
in sediment, water and fish do not appear to pose a threat to ecological receptors, DDT
levels continue to pose a threat, particularly to piscivorous birds. Existing food web models
that predict changes in bird or marine mammal COC body burdens need to be reassessed
with new data and improved understanding of sediment to fish bioaccumulation
correlations. Until such work is completed, the ambient water quality criteria for ecological
health, discussed in the following section, provides a quantifiable level of protection for fish
and wildlife.
• Support the Natural Resource Trustees' strategies to sustain wildlife recovery.
3.4.3 Water Quality
The ambient water quality criterion (AWQC) for protection of human health is 0.22 ng/L
DDT in water; this is the equivalent of 12 |o,g/kg DDT in fish tissue. The 0.064 ng/L PCBs in
water is the equivalent of 1.4 ng/kg PCBs in fish. These concentrations represent a 10'6
excess lifetime cancer risk. AWQC for ecological health are 1 ng/L DDT and 30 ng/L PCBs.
Water column data collected in 1997 (Zeng, 1999) measured concentrations of DDTs and
PCBs at different locations and depths in winter and summer. DDT and PCB concentrations
exceeded the AWQC for human health in all samples. All samples except one exceeded the
ecological health criterion for DDT. No water sample exceeded the PCB ecological standard
of 30 ng/L. Since the human health AWQC are lower than the ecological health AWQC, the
human health AWQC are selected as the remediation levels. As discussed in Section 2.4.4,
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3. REMEDIAL ACTION OBJECTIVES AND REMEDIATION GOALS
water column samples were analyzed for PCBs and DDTs in 1997 and 2003. Concentrations
of PCBs in the water column 2 meters above the bed over station 6C were 1.11 ng/L in 1997
and 0.56 ng/L in 2003. Additional sampling and analysis are necessary in order to calculate
when the human health criteria of 0.064 ng/L would be achieved.
RAO: Reduce concentrations of DDTs and PCBs in the surface waters over the PV Shelf to
acceptable levels that meet ambient water quality criteria for human health. The
AWQC will be calculated as the mean of water column concentrations of COCs over
the EA sediment deposit.
• Achieve AWQC for protection of human health (i.e., 0.22 ng/L DDT) within
30 years of remedial action.
• Collect and assess PCB data in order to determine schedule to meet AWQC
for PCBs (i.e., 0.064 ng/L) by first Five-Year Review.
RAO: Minimize potential adverse impacts to sensitive habitats and biological communities
on the PV Shelf during remedial action.
• Before implementation of any remedy, prepare a monitoring program to assure the
kelp beds on PV Shelf are protected.
Use low-impact techniques and other best management practices, e.g., plan field
work for season when tides and currents are less energetic, measure current speeds
before dredging or capping, monitor activities, i.e., sediment resuspension, COCs in
water column, and stop action if monitoring plan standards are exceeded.
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4.0 Identification of General Response Actions
and Screening of Remedial Technologies
This purpose of this step of the FS is to develop an appropriate range of waste management
options that will be analyzed more fully in the detailed analysis phase, i.e. Section 5.0, of the
FS. Appropriate waste management options that ensure the protection of human health and
the environment may involve, depending on site-specific circumstances, the removal or
destruction of hazardous substances at the site, the reduction of concentrations of hazardous
substances to acceptable health-based levels, and prevention of exposure to hazardous
substances via engineering or institutional controls, or some combination of all of these
options.
This section describes the screening process used to evaluate remediation technologies for
the PV Shelf site. The RAOs, developed in conjunction with the remedial investigation and
risk assessments, establish the basis for identifying general response actions (GRAs). GRAs
are broad categories of actions such as treatment, containment, disposal, or combination of
these. Specific categories of GRAs identified for contaminated sediments are as follows:
• No Action;
• Institutional Controls;
• Monitored Natural Recovery;
• Containment;
• Removal;
• In situ Treatment;
• Ex situ Treatment.
4.1 Description of General Response Actions (GRAs)
No Action
Consideration of a "No Action" response is required by the National Contingency Plan
(NCP) [see 40 CFR Section 300.430(e)(6)] as a baseline against which the performance of
other remedial alternatives can be compared. Under the No Action alternative, no remedial
action would be performed. There are no technologies or process options associated with
this GRA.
Institutional Controls
Institutional controls (ICs) are restrictions on land use or resource use to limit exposure to
hazardous substances. ICs are nonengineered instruments such as administrative or legal
controls that reduce exposure to contaminants of concern (COCs) by limiting or controlling
activities that could lead to human exposure. Institutional controls typically are used in
conjunction with engineering measures.
Monitored Natural Recovery
Natural recovery refers to the processes by which concentrations of COCs in impacted
media decline over time by natural processes such as biodegradation, burial, or dilution.
Reductions in the concentrations of even persistent pollutants may occur over time as a
/MAY09PVS CHART 4.DOC 4-1
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
result of natural processes. However, not all natural processes result in risk reduction and
for those that do, time frames required to achieve significant reductions must be calculated
and it must be determined whether the time frame is reasonable and acceptable.
Containment
Containment involves the physical isolation and immobilization of contaminants in
sediment. Capping is a common method used in lakes, bays, marine, and riverine
environments for containing impacted sediments. No sediment treatment occurs other than
by natural processes under the cap surface. Assuming effective cap placement, the
bioavailability and mobility of contaminants present in the sediment would be immediately
limited.
Removal
Sediment removal by dredging or excavation is another common practice for managing
contaminated sediment. Following removal, the material is usually taken to a treatment or
disposal facility. Dredging typically includes other unit processes such as:
• In-water controls to minimize contaminant resuspension during removal;
• Dewatering to reduce volume of sediment by reducing moisture content;
• Treatment of dredge water before discharge; and
• Disposal and/or treatment of dredged material.
In Situ Treatment
In situ treatment involves chemical or biological methods for reducing contaminant
concentrations or bioavailability without first removing the sediment. Chemical oxidation
treatments (for example, persulfate or iron/hydrogen peroxide [Fe/JrhCk]) are designed to
either chemically destroy or reduce the toxicity of the contaminants. In situ chemical
treatment may be carried out alone or in conjunction with biological treatment. Biological
treatment can be used to destroy (e.g., complete conversion to carbon dioxide [CCy or
methane) or reduce the toxicity of both DDTs and PCBs. Success is dependent on such
factors as sediment redox conditions, pH, microbial communities present, and
concentrations of microbial nutrients.
Ex Situ Treatment
Ex situ treatment involves the application of treatment technologies to transform, destroy or
immobilize COCs following removal of the contaminated sediments. Ex situ treatment
technologies require sediment removal (i.e., dredging), generally followed by dewatering of
the sediment and treatment of both the dewatered sediment and water. This approach
requires treatment application in a nearby confined facility where technologies use physical,
chemical, biological, and thermal processes to remove contaminants from the sediment.
4.2 Summary of Technology Screening Process
As described in EPA's Interim Final Guidance for Conducting Remedial Investigations and
Feasibility Studies Under CERCLA (EPA, 1988a), GRAs are initially evaluated by screening
technologies and process options associated with each GRA for the medium of interest.
First, a list of potentially applicable technologies is prepared based on the GRAs and on
available information on various technologies and processes that either exist or are under
development. Then the list is refined by evaluating each technology for implementability,
effectiveness, and relative cost. Technologies are either retained for use in developing
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
remedial alternatives or are dropped from further consideration. The following provides an
overview of the review process:
• The initial step involves assembling a comprehensive list of technology types and
specific process options applicable to the GRAs discussed in section 4.1.
• Potential technologies are screened against three criteria: implementability,
effectiveness, and relative cost.
• The results of the technology screening and a brief description of the primary factors
that influenced the retention/elimination screening decisions are followed by a list
of retained technologies and process options. These remedial technologies and
processes are carried into the development and screening of alternatives (Section
5.0).
• In sum, the FS process starts with a wide range of potential remedial options and,
through methodical evaluation, screens out GRAs, technologies, and process
options. As the FS process continues, only feasible remedial alternatives remain for
detailed analysis.
Evaluation of potential remedial technologies and process options requires consideration of
site-specific characteristics, including nature of the COCs, their concentrations,
contaminated medium, site constraints, and exposure pathways. Remedial technologies and
process options are then screened for effectiveness, implementability, and relative cost.
The COCs, DDTs and PCBs, are persistent, hydrophobic, organic chlorinated compounds
that are detectable in effluent-affected (EA) sediment over approximately 34 square
kilometers in very deep water. Evidence of the EA sediment deposit is found from water
depths of 40 m to over the shelf break (at 70 to 100 m) and down the slope. DDTs and PCBs
are found in sediment, water, and fish at the PV Shelf Study Area. The GRAs focus on the
EA sediment, as the present source of contamination, and on controlling exposure (i.e.,
consumption) of fish, as the pathway through which human and ecological health are
potentially at risk.
The GRAs describe remedial actions theoretically capable of achieving the RAOs described
in Section 3.0. The technologies are grouped according to the GRAs. One or more
technologies and technology process options may be considered within each GRA category.
Ancillary technologies that are necessary to the overall implementation of a cleanup
program, but secondary to the primary functions embodied in the GRAs, are also evaluated.
For example, sediment dewatering during removal or suspended solids control during
dredging are ancillary technologies.
4.2.1 Screening Criteria
The screening of technologies and process options in this section incorporates information
developed as part of the NRDA, Feasibility Study of Sediment Remediation Alternatives for the
Southern California Natural Resource Damage Assessment (NOAA 1994), Screening Evaluation of
Response Actions for Contaminated Sediment on the Palos Verdes Shelf (EPA, 1997) and the
Engineering Evaluation/Cost Analysis (EE/CA) (EPA, 2000). The EE/CA included response
actions involving dredging, capping, and institutional controls. Additional information
from these sources was used during development and evaluation of the site-specific
remedial alternatives in Section 5.0.
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
Applicable technology and process options have been identified for each GRA. For the
purposes of this FS, the term "remedial technology" refers to a general category of
technologies, such as in situ chemical treatment, capping, and monitored natural recovery
(MNR). The term "process option" refers to the material, equipment, or methodology used
to implement a technology. For example, dredging is a remedial technology under the GRA
of sediment removal and hydraulic dredging is a process option that could be used to
implement dredging.
The criteria used to evaluate each process option are implementability, effectiveness, and
relative cost. These criteria are discussed below.
4.2.1.1 Implementability
Technical implementability refers to the technical feasibility of implementing a particular
technology. Technologies that are not applicable to site characteristics or the COCs are
eliminated from further consideration. Administrative implementability considers
permitting and the availability of necessary services and equipment to implement a
particular technology.
4.2.1.2 Effectiveness
Determining the effectiveness of a technology involves consideration of whether the
technology can contain, reduce, or eliminate the COCs and achieve the RAOs. Effectiveness
is evaluated relative to the other technologies identified in the screening. Consideration
must also be given to the many aspects of remediation that contribute to a technology's
overall effectiveness including:
• How well the technology will handle the estimated areas or volumes of
contaminated sediment to be remediated;
• If the RAOs will be met through implementation of the technology;
• How efficiently does the technology reduce or eliminate the COCs;
• To what degree the technology has been tested and proven;
• How quickly the technology can be implemented; and
• How effective is the process option in protecting human health and the environment
during implementation.
4.2.1.3 Cost
Technologies were evaluated with respect to capital and operations and maintenance
(O&M) costs. Detailed cost estimates of remedial alternatives are provided in Section 6.0 of
the FS Report. Costs used for screening purposes are defined in terms of high, moderate,
and low, rather than a specific dollar amount and are determined on the basis of
engineering judgement and/or previous experience at the site. The cost of each process
option relative to the other process options in the same technology type is compared.
When multiple process options are considered effective, implementable, and cost-effective, a
representative process option is chosen for development and analysis. Retained
technologies and process options will be combined into site-specific remedial alternatives.
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
4.3 Evaluation and Screening of Remedial Technologies
General descriptions of the technologies and process options for each of the general
response actions (GRAs) are provided below. Based on the evaluation of the technologies
and process options, some of the GRAs may be screened out as infeasible.
4.3.1 No Action
The National Contingency Plan (NCP) (see 40 CFR Section 300.430[e] [6]) requires
consideration of a no action GRA as a baseline to compare against other remedial
alternatives. Under the no action alternative, no response action would be performed, and
contaminated sediments would be left in place. There are no technologies or process
options associated with this GRA.
4.3.1.1 Implementability
There is no implementation associated with no action.
4.3.1.2 Effectiveness
The no action alternative is unlikely to meet RAOs, nor would any action be taken to verify
recovery.
4.3.1.3 Cost
No action, by definition, would have no associated costs.
4.3.2 Institutional Controls
Institutional controls (ICs) are restrictions on land use or resource use thT limit exposure to
hazardous substances. ICs are nonengineered instruments such as administrative or legal
controls that limit land or resource use to prevent activities that could expose humans or
wildlife to contamination. Institutional controls typically are used in conjunction with
engineering measures.
Institutional controls have been implemented at the PV Shelf site for a number of years.
Since 1985, the State of California has issued fish consumption and health advisories for the
Southern California coast. These warnings have been included in the California sport
fishing regulations since March 1,1992.
In 1990, the California Department of Fish and Game (CDFG) imposed a commercial fishing
ban on white croaker specific to the PV Shelf based on the health risk advisories provided
by the CalEPA Office of Environmental Health hazard Assessment (OEHHA). The
commercial fishing ban extends 3 miles out from the shoreline from Point Vicente to Point
Fermin. In March 1998, in response to concerns about white croaker being sold illegally by
sport fishermen to commercial fish markets, CDFG revised the white croaker recreational
catch limit from unlimited to 10 fish per day.
In 2001 EPA prepared an Action Memorandum that put in place an institutional controls
program for PV Shelf. The 10-year program established a three-pronged approach to limit
human exposure to potentially contaminated fish from PV Shelf: public outreach and
education, enforcement, and monitoring. For remedial identification and screening
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
purposes, institutional controls constitute a remedial technology. Elements of the
institutional controls program for PV Shelf include the following: outreach and education,
enforcement, and monitoring. More information about the program can be found in
Appendix D, which contains the Palos Verdes Shelf Superfund Site Institutional Controls
Program Implementation Plan (draft 2009).
Public Outreach and Education
The current program conducts outreach in four primary areas: piers, commercial fish
markets, the media, and general outreach. Pier outreach is designed to educate anglers in
the Los Angeles area about the site history, fish advisories, identification of contaminated
fish, and safe fish-consumption practices. Outreach to commercial fish markets is
conducted to inform markets and restaurants of the dangers of buying fish from unlicensed
dealers who may be taking fish from restricted areas. Media outreach is used to inform the
general population of the health risks of eating contaminated fish from the PV Shelf through
media circulation throughout Los Angeles and Orange Counties. Finally, the general
outreach program partners with health and community fairs and local health departments
to provide educational materials and training to affected communities. The components of
the outreach program have been and would continue to be conducted in several languages
commonly spoken in the Los Angeles area.
Enforcement
Enforcement of the commercial catch ban on white croaker off the Palos Verdes Peninsula
and the daily recreational catch limit for white croaker reduces the likelihood that
contaminated fish will be sold to consumers at public markets. Enforcement of the catch
ban is implemented by the California Department of Fish and Game (CDFG) and includes
patrolling the catch ban area along with all of the surrounding areas for sport and
commercial take of white croaker, as well as monitoring landing data (catch block, landing
port, species, gear used, value, and weight of fish) and fish business inspections. All of the
enforcement efforts of the CDFG fall within their normal areas of responsibility. However,
more emphasis has been directed on white croaker starting in 2009.
Monitoring
The fish monitoring program includes sampling fish from designated ocean locations in the
PV Shelf area as well as fish from local markets to keep messages up-to-date on which
species have lower COC body burdens and which should be consumed in limited
quantities. The 2002/2004 Southern California Coastal Contaminants in Fish Study (EPA/MSRP
2007) also assessed the effectiveness of the enforcement program by evaluating whether
contaminated fish from the PV Shelf are reaching local fish markets, and whether the catch
ban boundaries are still adequate.
EPA visited 55 markets in Los Angeles County and 13 markets in Orange County from July
2004 through January 2005. The market list was based on previous studies (Heal the Bay,
1997, and S.R. Hanson & Associates, 2000), and markets that were identified by community
based organizations from the Fish Contamination Education Collective (FCEC). After
repeated visits, six markets (4 in Orange county and 2 in Los Angeles county) out of 68
markets were found to carry white croaker. Five white croaker were purchased at each of
the six markets. Concentrations of contaminants in white croaker fish fillet ranged from 12
mg/kg to 0.058 mg/kg DDTs and from 1 mg/kg to and 0.027 mg/kg PCBs (CH2M HILL
2006). All of the white croaker exceeded the RME targets for DDTs, and three of the six
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
markets sold white croaker with DDT concentrations above the CTE target. All of the
markets had white croaker that exceeded both the RME and CTE targets for PCBs. The
higher levels of DDTs and PCBs are consistent with the contaminant levels found in white
croaker in the commercial catch ban area.
Monitoring, as an ICs process option, would include studies to better identify areas where
recreational or subsistence fishing can occur and which species should be consumed in
limited quantities.
4.3.2.1. Implementability
The ICs program has been in place since 2001. The processes involved in the ICs program
are generally easy to implement as long as there is adequate staff and adequate funding, as
discussed in more detail in Appendix D. The multi-agency coordination and large area
under the program pose challenges. Public outreach and education for the Los Angeles area
is challenging given the plethora of media messages that area residents are exposed to on a
daily basis. Enforcement of the commercial catch ban and bag limit are challenging as well.
The commercial catch ban area covers small portions of catch blocks 719 and 740 and all of
block 720. In 2007, landing data indicate no white croaker were caught in blocks 719 and
720 and 27,585 pounds of white croaker were caught in block 740. In the absence of
evidence to the contrary, EPA assumes all of the fish were caught outside the catch ban area.
An increase in CD EG patrols in 2009 will lend support to the effectiveness of the catch ban
area.
4.3.2.2 Effectiveness
The public outreach and education program has conducted surveys to measure the
effectiveness of its activities. It has found that a majority of anglers in the area have heard
the messages on safe fish-consumption habits and their role in reducing the risk to human
health. More recently, the program has focused on attempting to quantify behavior changes
attributable to its initiatives.
Continued enforcement of commercial fishing bans and the sport-fishing bag limit of 10 fish
per day for white croaker is a potentially effective measure for reducing the number of
contaminated fish reaching the marketplace. However, as the market monitoring discussed
above illustrates, fish with contaminant concentrations outside of the EPA risk range are still
reaching consumers. Enforcement appears to be controlling the quantity of fish that reach
markets but not necessarily the quality. Additional measures to increase the effectiveness of
enforcement warrant consideration.
The fish monitoring program is effective when used in combination with the other
institutional controls to help assess if enforcement and outreach programs are preventing
contaminated fish from reaching the marketplace.
This process option has the potential to effectively curb human health risk; however,
institutional controls cannot protect ecological receptors.
4.3.2.3 Cost
Costs for institutional controls are generally less than technology-based cleanup options that
involve containment, removal or treatment. The task of enforcement is borne largely by the
State, i.e., CDFG with support from local governmental health departments. Administrative
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
and regulatory barriers prevent EPA from directly implementing enforcement activities.
However, EPA can provide financial assistance to state and local agencies through
cooperative agreements.
4.3.2.4 Screening Decision
Institutional Controls are important features of many sediment cleanup projects and are
retained for further consideration in the development of remedial alternatives. The
management of some remedial actions and management of residual risk after remediation
will likely require implementation of ICs for a period of time until the monitored natural
recovery goals and project RAOs are achieved. ICs are retained.
4.3.3 Monitored Natural Recovery
Natural recovery involves one or more processes that effectively reduce or isolate
contaminant toxicity, mobility, or volume. These processes include physical, chemical, and
biological processes. Monitored natural recovery may be an appropriate remedial
alternative when:
• large volumes of contaminated sediment have marginal levels of contamination;
• the area is a low-energy, depositional environment;
• dredging for navigational needs are not required;
• site restrictions and institutional controls can effectively limit exposure;
• review of existing data suggest that the contamination is naturally attenuating and
will likely achieve the remediation goals within an acceptable time frame; and
• the cost for an active remedy disproportionately outweighs the risk reduction
benefit.
The PV Shelf meets many of these criteria. As discussed in section 1.2.5, the PV Shelf Study
Area can be divided into different areas. By depth, the area can be divided into the inshore
region, the fairly level shelf, and the steep slope. From east to west, the shelf is divided by
the outfalls at White Point into southeast of the outfalls, north-northwest of the outfalls, and
the area around the outfalls. The EA deposit does not extend into shallower waters. The
area southeast of the outfalls has low levels of contaminants mixed in the sediment, but
prevailing currents kept the deposit from forming there like it did north of the outfalls (see
Figure 1-8). The area north of the outfalls has highly contaminated sediment covered by
approximately 30 cm of cleaner sediment with lower surface contaminant concentrations.
Data and modeling suggest the most contaminated sediment in this area may stay buried.
Additionally, the buried deposit of DDT appears to be undergoing reductive dechlorination.
The outfall area has surface sediment concentrations of contaminants an order of magnitude
greater than other areas. In addition, the buried "peak" of contaminated sediment around
the outfalls appears to be moving upward, toward the surface. Finally, the slope is too steep
for a thick sediment layer to develop; however, the slope has areas of high surface
contaminant concentrations.
Monitored natural recovery (MNR) may rely on a wide range of naturally occurring
processes to reduce risk to human health and ecological receptors. These processes may
include physical, biological, and chemical mechanisms that work together to reduce the risk
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
posed by the contaminants. Under MNR risk reduction is achieved in one or more of the
following ways:
• The contaminant is converted to a less toxic form through transformation processes,
such as biochemical degradation or abiotic transformation.
• Loss of contaminants through diffusion into overlying water.
• Exposure levels are reduced by a decrease in contaminant concentration levels in the
near-surface sediment zone through burial or mixing-in-place with cleaner sediment.
• Exposure levels are reduced by a decrease in contaminant concentration levels in the
near-surface sediment zone through dispersion of particle-bound contaminants or
diffusive or advective transport of contaminants to the water column.
MNR usually involves acquisition of information over time to confirm that identified risk-
reduction processes are occurring as predicted. MNR would measure reductions of
contaminants in sediment, water and fish against the remediation goals set forth in Section
3.4. MNR can be combined with engineering approaches, e.g., placement of a thin layer of
clean sediment to support existing cover or addition of an amendment to accelerate
contaminant breakdown. These combined approaches are referred to as Enhanced Natural
Recovery.
As discussed in Section 2.4, there is evidence that PV Shelf is undergoing natural recovery.
The following processes have been observed.
Natural Dechlorination.
In 1972, one year after inputs of DDT to the LACSD sewer system had ceased, the DDT
composition of sediment on the PV Shelf was found to be dominated by DDE. Existing
information suggests that this was the result of dehydrochlorination of DDT that occurred
shortly after discharge of DDT-bearing wastes form the JWPCP outfalls. The DDT
composition of shelf sediments showed little change between 1972 and 1992 when, for the
first time, DDMU was measured in the sediment as part of the Natural Resources Damage
Assessment Program. The presence of DDMU in all sediment samples collected in 1992 and
its increased relative abundance with depth in many cores suggested that reductive
dechlorination of DDE was taking place. However, initial estimates of maximum first-order
transformation rates near LACSD station 3C, based on the assumption that DDMU was a
dead-end product, were relatively low (0.028 yr1). Microcosm experiments published in
1998 demonstrated unequivocally that reductive dechlorination could be mediated by
microorganisms present in PV Shelf sediment (Quensen et al., 1998). These experiments
also showed that dechlorination rates varied spatially with higher rates in sediment
collected farther from the outfalls (e.g., station 3C). The microcosm-based dechlorination
rates determined for sediment from station 3C were much higher than those estimated from
the aforementioned 1992 core analyses (0.99 yr1 vs. 0.028 yr1).
In 2006, USGS performed a core-to-core comparison of sediment cores that had been
collected near station 3C in 1992 and 2003 (Eganhouse, 2007). The 2003 core was analyzed
for 8 DDT compounds, 84 PCB congeners, and 38 long-chain alkylbenzenes. This provided
a means of estimating DDE transformation rates for the period 1992-2003 through
comparison of DDE whole-core inventories and DDE concentrations in coeval sediment
layers. The analyses show that the whole-core inventory of DDE decreased by 43.2 percent
from 1992 to 2003, whereas inventories of DDMU and DDNU increased by 33.5 percent and
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
33 percent, respectively, during the same period. The estimated first-order DDE
transformation rate based on whole-core inventories was 0.051 yr1.
Limited data are also available for other locations on the shelf. Based on comparison of
whole-core inventories of DDE in sediment collected by the LACSD at station 6C in 1991
and 2005, rates of 0.013-0.028 yr-1 were obtained. These are approximately 2 to 3 times lower
than those at station 3C.
In contrast to DDE, the cores showed no evidence of reductive dechlorination of PCBs. The
reported differences in surficial contaminant concentrations may be a reflection of this.
Vertical Profiling and Biodiffusion
Because the highest concentration of DDT/DDE is buried, sedimentological studies focused
on how organisms that live in the sediment transport contaminants upward. As discussed
in section 2.5, in the 1990s, investigations for the NRDA (Wheatcroft and Marten, 1996)
measured both the physical and biodiffusive rates for contaminant transport. Other
investigations focused on how water column processes resuspend and transport
contaminants. These results show that contaminants are indeed being mixed to the surface
of the sediment bed, primarily through biodiffusion. Once they reach the seabed, surface-
wave-induced currents resuspend them and subtidal currents transport them.
In 2004, additional studies of biodiffusion and sediment mixing were undertaken (SAIC,
2005). Radioisotopes were used to calculate sediment mixing/bioturbation rates. Profiles of
thorium-234, which decays rapidly (24.1-day half life), were used to evaluate bioturbation
and mixing in the sediment surface. Profiles of excess lead-210 (22.3-year half life) were
used to determine sediment accumulation rates at four stations across the shelf.
Biodiffusivity values based on the thorium-234 profiles, coupled with sedimentation rate
data from the lead-210 analyses, indicate low sediment mixing intensities (i.e, average of 19±
21 cm2/yr vs. 1992/93 values of 31± 20 cm2/yr). Sediment accumulation rates from the
lead-210 data were low (about 0.8 to 1.6 mm/yr). There was some indication that the
sediment accumulation rate was relatively lower in the southeast portion of the study area.
Thorium-234 results indicated biodiffusive mixing to about 6-cm sediment depths, generally
consistent with historical data on the principal vertical distributions of the infaunal
community. Overall, data from the 2004 assessment indicate low sediment mixing
intensities below surface layers and low biomass and abundance of deep bioturbating
infaunal organisms (BIOs).
Evidence of low sediment mixing can be seen by an examination of LACSD sediment cores.
LACSD has taken sediment cores from many of their sampling stations throughout the
years. Cores taken across the 60-m isobath create an historical record of the sediment
deposit. Figures 2-8 and 2-9 provide multiyear sampling data for stations 3C and 6C,
indicating changes in contaminant concentration and location of peak contamination.
Figure 2-10 shows profiles for all 60-m stations.
Sediment Deposition
Historical (pre-outfall) sedimentation rates have been estimated at approximately 0.1 to 0.2
cm/year (Lee et al., 2002). Discharge of suspended solids from the JWPCP outfalls along
with erosion of the Portuguese Bend Landslide added millions of metric tons (mt) of
sediment to the shelf. Sedimentation rates have dropped substantially since JWPCP
implemented secondary treatment of wastewater in 2002. Present TSS emission rate is 8,000
mt/yr, down from the historical high of 167,000 mt/yr in 1971. Recent calculations indicate
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
the area over the contaminated sediment deposit remains depositional, although rates have
dropped (Sherwood 2006). Based on the process model included as Appendix B and
described in section 2.5, the shelf may be capable of natural recovery over time.
Sediment Transport and Burial
Analysis of surficial contaminant concentrations over time indicate median DDT
concentrations went from 4.0 mg/kg in 1992, to 2.5 mg/kg in 2002, and 2.0 mg/kg in 2004.
During the same period, PCBs (as sum of six Aroclors) went from median concentration of
0.5 mg/kg in 1992 to 0.6 mg/kg in 2002 and 0.3 mg/kg in 2004. As shown in table 1-1, the
extent of contamination in surface sediment has decreased. From 1992 to 2002/2004, the
surface area exceeding 10 mg/kg DDTs has dropped 56 percent, from 8.2 km2 to 3.6 km2.
For the same time period, the area exceeding 1 mg/kg DDTs decreased 12 percent, from 44.5
km2 to 39.1 km2; and the area exceeding 1 mg/kg PCBs decreased 26 percent, from 8.4 km2
to 6.2 km2. The reduction in surficial concentrations of DDTs and PCBs are attributed to
physical, biological, and, in the case of DDTs, chemical processes. Loss processes that are
important at PV Shelf include sediment transport and deposition, physical reworking of
sediment by waves and currents, resuspension and desorption, and biological mixing or
transport of sediment and liquid-phase contaminants (i.e., in pore water).
4.3.3.1 Implementability
The technical and administrative implementability of MNR is high. Sampling techniques
for water, sediment and fish are proven. MNR is not expected to require construction
activities, and thus will be less disruptive to the ecological community compared with other
remedial technologies. Modeling of sediment fate and transport included in Appendix B, is
used to predict recovery rates, loss rates, and reductions in concentrations of COCs. Field
monitoring to validate and refine modeling would be required.
4.3.2.2 Effectiveness
Monitored natural recovery may be an appropriate remedial alternative for certain areas of
the site. Some areas, such as the northwestern region, appear to be net depositional and the
contaminated mass is likely to stay buried. Other areas, such as the slope, cannot be actively
remediated.
Although deposition rates along the 60-m isobath have been calculated from the LACSD's
multi-year data set, the rates appear to have dropped since LACSD implemented full
secondary treatment of effluent. Studies to calculate current deposition rates and effects of
winter storms on the sediment deposit are underway. Depending on rates of sedimentation
and erosion, median concentrations of DDTs in surface sediment associated with
remediation goals in fish tissue may be reached in 45 to over 100 years, and water quality
standards may be met within 30 to 60 years. Additionally, under one scenario (Sherwood,
2002) the area around the outfalls would reach low contaminant surface concentrations
through erosion of as much as 80 percent of the deposit, which would be transported off the
shelf into deeper waters.
MNR may be effective in the long term, but not in the short term. Comprehensive
monitoring and an evaluation of the study area would be essential to assess the rate and
effectiveness of MNR for the PV Shelf and to assure that the contaminated sediment is not
merely distributed into other areas. Potential risk to human health and the environment will
remain during the implementation phase of MNR.
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4.3.3.3 Cost
MNR is generally considered a low-cost technology because no active remediation occurs
that involves containment, removal, or treatment of sediment. However, monitoring costs
may be significant, extending into the millions of dollars, depending on the term and
magnitude of the monitoring program. Long-term monitoring costs vary widely depending
upon the project expectations, media of concern, and residual risks. Because of the
complexity of the site, the cost for MNR will be relatively high compared with MNR for
other sites.
4.3.3.4 Screening Decision
MNR is retained for remedial alternative development.
4.3.4 Enhanced Monitored Natural Recovery
For the PV Shelf Study Area there are two potential actions to enhance the natural recovery
processes:
• Controlling conditions to encourage natural degradation
• Adding a thin layer of clean sediment over contaminated sediment to reduce surface
concentrations of contaminants and stabilize sediment erosion
Both of these approaches are described in more detail below.
Enhanced Natural Degradation
Controlling conditions to accelerate the natural degradation process would consist of
determining the primary mechanisms for degradation and enhancing it through the
addition of substrate, or otherwise changing the site conditions to encourage degradation.
As discussed above, biochemical degradation of DDE is occurring at the site and could be a
significant mechanism for natural recovery. However, the mechanism driving reductive
dechlorination of DDE is not known. Additionally, once the degradation mechanisms are
identified finding a mechanism to accelerate degradation in situ, given the depth of the
deposit and the fact that the buried sediment is where the degradation is most pronounced,
make enhancement to accelerate degradation challenging. As stated previously, there is no
evidence PCBs are degrading; therefore, enhanced natural degradation through reductive
dechlorination would not reduce the risk from PCBs.
Clean Sediment Amendment
The placement of a thin-layer cap is another approach to enhance MNR. Thin-layer capping
is discussed under section 4.3.5 Containment. Briefly, a 10 to 15 cm thin-layer cap of clean
sand would be placed over the deposit with the expectation that it would mix in with the
EA sediment, supplementing and diluting the existing surface sediment. As the finer EA
sediment erodes, the clean material would remain, reducing COC surface concentrations.
4.3.4.1 Implementability
The implementability of enhanced MNR through clean sediment amendment is moderate to
high. The depth of PV Shelf poses a challenge; however, techniques to accurately deliver
sediment at depths are available.
4.3.4.2 Effectiveness
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The effectiveness of enhancing MNR through controlling degradation of the contaminants is
low because the mechanisms for degradation are not fully understood and even if the
mechanisms were identified, the depth of the EA sediment deposit would make
implementation difficult. In addition, PCBs do not appear to be degrading.
The effectiveness of enhanced MNR through a thin cap is estimated to be moderate to high.
The mixing that would occur and the potential for armoring of the surface layer are likely to
enhance the natural recovery and are thought to be promising. However, additional
information on type of material and best placement locations and techniques would need to
be collected as part of a pilot project or other type of treatability study.
4.3.4.3 Cost.
The cost for enhanced MNR would be high because this technology requires more research
and understanding prior to implementation. As described below under "Containment/'
capping material and the placement of a thin-layer cap would be costly to implement.
Adding a substrate or controlling site conditions also would be costly.
4.3.4.4 Screening Option
Enhanced MNR is retained for remedial alternative development.
4.3.5 Containment
Containment or in situ capping refers to the placement of a subaqueous covering or cap of
clean material over contaminated sediment. Containment does not require removal of
sediment; clean sediment is placed over old sediment as a barrier, isolating contaminants
within the substrate. Capping has become an accepted engineering option for managing
subaqueous contaminated sediment.
In situ capping can quickly reduce exposure to contaminants and, unlike dredging or
excavation, requires less infrastructure in terms of material handling, dewatering, treatment
and disposal. A well-designed and well-placed cap should reduce the exposure of fish and
other biota to contaminated sediment more quickly than dredging, since there should be no
or very little contaminant residual on the surface of the cap. Cap placement eliminates the
majority of the benthic community, but creates a clean substrate for recolonization. In some
cases, it may be desirable to select capping materials that discourage colonization by native
deep-burrowing organisms to limit bioturbation and release of underlying contaminants.
The major limitations of in situ capping is that the contaminated sediment remains in the
aquatic environment where contaminants could be exposed or be dispersed if the cap is
disturbed or if contaminants move through the cap in significant amounts. In some
environments it can be difficult to place a cap without significant contaminant losses from
compaction and disruption of the underlying sediment. Shear strength, especially
undrained shear strength, of contaminated sediment deposits is of particular importance in
determining the feasibility of in situ capping. Most contaminated sediment is fine-grained,
and is usually high in water content and relatively low in shear strength. Although a cap
can be constructed on sediment with low shear strengths, the ability of the sediment to
support a cap and the need to construct the cap using appropriate methods to avoid
displacement of the contaminated sediment must be considered. Movement of dissolved
contaminants by advection (flow of pore water) through the cap is possible, while some
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
movement of contaminants through molecular diffusion is inevitable. Cap thickness and
cap material can minimize chemical flux.
Capping operations can disturb and displace loose fine-grained bottom sediment, resulting
in resuspension losses and mixing of contaminants into the clean capping layer. Physical
characteristics, such as solids content, plasticity, shear strength, consolidation, and grain size
distribution affect the displacement of sediment. The sediment characteristics will often
form the basis for determining the suitability of capping materials and placement options
(Palermo 1991).
The method used to place the cap material must be capable of achieving even placement of
material over the target area while limiting the resuspension and loss of contaminated
sediment into the water column or the emerging cap layer. Even placement and limited
resuspension of contaminated sediment are generally achieved when the capping materials
are dispersed and allowed to settle through the water column. The dumping of large, dense
masses of capping material (e.g. pushing sands off a barge) or methods that lead to density-
driven hydraulic flow should be avoided.
Installation of an in situ, subaqueous cap requires consideration of the following issues:
• The type of capping material with regard to isolation of sediment and protection of cap
and sediment against erosion due to environmental factors (wave, current, benthic, etc.)
• The amount (thickness) of capping material required with regard to isolation of
sediment against benthic activity or contaminant flux through advection or diffusion
• The amount of capping material required with regard to the required accuracy of
placement, gradation of material, and physical/chemical makeup of material
(i.e., reactive material or organic substrate)
• The total amount of material required based on the area to be capped and an assumed
loss factor through the water column and mixture with the contaminated sediment
• The equipment available and applicable to the area being worked such as shallow water,
deep water, open water, lakes, etc.
• The available sources for capping material and proximity to the site
• The techniques that are applicable for the particular situation such as low impact/high
accuracy/high volume or high impact/low accuracy/low volume
• The ability to isolate portions of the water body such that turbidity and resuspension
do not impact offsite areas
• The affect that placement of material has on the in situ sediment, consolidation,
resuspension, mixing, change in redox potential, and bottom failure
Ancillary processes associated with containment technologies include:
• Cap material placement
• Cap placement methods
• Resuspension management
• Residual management
• Cap material conveyance/transport
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
Cap Material Placement
Caps can be grouped into three general categories: conventional sand, armored and
composite. Conventional capping includes sand and clay caps. Armored capping adds
heavier material on top of a conventional cap to add physical stability in erosive
environments. Other miscellaneous capping techniques include thin-layer capping and
enhanced capping.
Conventional caps involve the placement of sand or other suitable cover material (e.g., clay)
over the top of contaminated sediment. Material selection and cap thickness are determined
based on consideration of contaminant properties and local hydraulic conditions. Sandy
soils and sediments are typically preferred as cap materials over fine-grained materials. The
latter are more difficult to place evenly, cause a great deal of turbidity during placement and
are more erosive (Palermo 1994).
Armored caps are similar to conventional caps with the exception that the primary capping
material, e.g., sand, is covered with stone or other suitable riprap (the armor) to add
physical stability in erosive environments. Armored caps are commonly used in
environments where high water velocities threaten cap integrity.
A composite cap generally involves placement of a geotextile or flexible membrane liner
directly over the contaminated sediment. Permeable or impermeable liners may be
considered, depending upon the migration potential of the COCs, and the potential for
methane buildup under the liner in highly organic sediments. The liner is then armored
with stone or riprap to ensure the physical integrity of the cap. Composite caps may also
include a sand or activated carbon layer to capture any potential diffusion or advective
migration of the underlying contaminants. Composite caps have size and depth limitations.
Additional capping approaches have been tried or are under development, for example,
thin-layer capping or use of special capping materials, e.g., Aquablok®. Thin-layer capping
involves the placement of a thin (5 to 10 cm thick) layer of clean sediment, that is
subsequently mixed with the underlying contaminated sediment to achieve acceptable COC
concentrations and/or enhance the natural attenuation processes. Mixing occurs naturally
as a result of benthic organism activity (bioturbation). This approach is best suited for
situations involving contaminants that naturally attenuate over time.
The effectiveness of capping can be increased by incorporating special materials, such as
activated carbon, iron fillings, Aquablok® or other agents into the base capping material
(e.g., sand) to enhance adsorption or in situ chemical reaction. This approach targets
sediment in which contaminants are mobile and are expected to migrate through the cap as
dissolved constituents in the pore water.
Placement Methods
Various equipment types and placement methods have been used for capping projects.
Important considerations in selection of placement methods include the need for controlled,
accurate placement of capping materials. Slow, uniform application that allows the capping
material to accumulate in layers is often necessary to avoid displacement of or mixing with
the underlying contaminated sediment. Uncontrolled placement of the capping material
can also result in the resuspension of contaminated material into the water column and the
creation of a fluid mud wave that moves outside of the intended cap area.
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
Most available techniques for placement of cap material can be classified as either
mechanical or hydraulic. Mechanical placement techniques include clamshells, split-hull
barge and split-hull hopper dredge, flat-deck barge using a bulldozer to push material over
the edge of the barge, long-handled backhoes, and skip buckets on cranes. Conveyors also
have been used to cap areas beneath structures or in shallow draft areas. Fallpipes or tremie
tubes used with a clamshell bucket or conveyor can be used in areas of deep water where
placement of cap material requires precision. Mechanical methods such as split-hull barges
and split-hull hopper dredges can carry 1,000 m3 of capping material or more and place it
very rapidly using point dumping techniques (resting in one place while opening the split
hull). A split-hull barge or hopper dredge also can slowly open the hull doors while
moving through an area, and release material more slowly and with relatively lower impact.
This method is known as a spreading placement technique. Both point placement and the
spreading technique are rapid compared to other placement techniques.
Mechanical placement using a clamshell can be conducted by point dumping above the
water line or just above the mudline. Material released from the clamshell above the
waterline is performed by casting the material while opening the bucket (open on the
swing) and will have relatively low impact when the cap material falls onto the mud
bottom. The impact of clamshell point placement also can be reduced by lowering the
clamshell to several feet above the bottom and opening it. Material released above the
mudline is a slower placement technique with higher precision of placement. Material
placement also can be achieved by loading a skip bucket (usually loaded with an end-loader
or backhoe) and point dumping or casting.
Hydraulic placement techniques include pumping slurry to the site, hydraulically sluicing
material off the deck of a flat-deck barge, and spraying or sprinkling a slurry of material.
The methods differ primarily in the speed of placement, the accuracy of placement, and the
impact or energy of the material placed on the bottom sediment. Tremie tubes can be used
with hydraulic placement methods. Similar to using a tremie tube with mechanical
placement, projects that require placement of the cap material with high precision can use
hydraulic methods. The slurry can be pumped into a tremie tube for placement near the
bottom. An energy dissipater, such as a diffuser or spoon, can be used to absorb energy and
spread the material before it impacts the bottom. Hydraulic methods offer the potential for
more precise placement, although the energy required for slurry transport could require
dissipation to prevent resuspension of contaminated sediment. Hydraulic placement
methods are typically slower (lower placement rate). Techniques such as pumping from a
barge using dredge equipment can move large quantities of material fairly rapidly and
fairly accurately as can sluicing from a flat-decked barge using a large water cannon.
Methods such as spraying a slurry are more applicable to very slow, accurate placement and
have been used in very shallow draft areas such as wetlands.
Resuspension Management
Placement of a sediment cap will involve in-water work, which can cause resuspension of
contaminated sediment. The resuspended contaminated sediment might be transported
outside the construction zone and settle in other areas. Resuspension of contaminated
sediment might cause impacts to aquatic biota adjacent to the construction zone. Therefore,
resuspension must be managed to minimize construction impacts.
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
Water quality impacts resulting from in-water construction would be limited to short-term
increases in suspended sediment in the construction area and advection of pore water
through the cap material during consolidation of underlying sediment.
Resuspension management would use best management practices (BMPs) during in-water
work. Engineering and in-water construction methods would be designed to minimize
resuspension. In addition, engineering design would minimize events such as slope failures
for removal and craters for cap placement.
Additional BMPs might include placing the cap with a tremie tube, using cap material that
has been washed or contains very few fines, installing the initial layer of cap material at a
slow rate to minimize resuspension, placing cap material using low-energy spreading
methods as opposed to high-energy methods, and using curtain barriers.
Curtain barriers consist of impermeable and permeable silt curtains. A silt curtain is
designed to contain sediment within a limited area and provide enough residence time that
sediment particles can fall out of suspension and not travel to other areas outside the
construction zone. The suspended silt curtain consists of either an impermeable or
permeable filter fabric curtain weighted at the bottom and attached to a flotation device at
the top. An anchor system attached to the flotation device at the top is typical, and an
anchor system at the bottom can be used for additional stability. The silt curtain type must
be selected on the basis of flow conditions in the area. Silt curtains are not designed to act as
water impoundment dams and cannot be expected to stop the flow of a significant volume
of water. They are designed and installed to trap sediment, not to halt the movement of
water. Anchoring these curtains would also be a challenge and may not be achievable with
even low currents.
Residual Management
Residual management is the process that addresses residual contaminated sediment left
behind after a remedial action because further containment is not practical. Contamination
that remains exposed after a capping operation is dependent on a number of factors,
including the cap placement method, skill of the operators, physical sediment properties,
thickness and areal extent of the cap, presence of obstructions such as the LACSD outfalls,
and site hydrodynamics such as currents and waves. Residual management is likely to
consist of risk evaluation to consider the uncapped areas or additional construction methods
to cap difficult areas.
Cap Material Transport/Conveyance
Transport/conveyance considerations would be required for alternatives involving
containment. Cap material would be transported from a fill source or vendor to the
project site.
Barge/Scow Transport
Typically, a barge, scow, or hopper dredge is used to transport sediment for placement.
Maneuvering a barge into position with a tugboat involves a number of logistical
considerations. Barges would typically be used to transport from a shoreline source, or in
combination with truck transport from an upland source. A hopper dredge would be used
to transport materials from an in-water source, such as borrow area or an ongoing
maintenance dredging project at a nearby port.
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
4.3.5.1 Implementability
The USAGE prepared Options for In Situ Capping ofPV Shelf (Palermo et al, 1999), included
as Appendix E to assess the feasibility of capping the shelf. USAGE determined that the
area between 40 m and 70 m was suitable for capping. Capping in water depth less than 40
m would require control measures to prevent erosion. Beyond 70 m, the slope increases to
greater than 5 degrees, which would be unsuitable for capping because of susceptibility to
flow failure under moderate seismic activity. The report discussed cap material, cap
thickness, and erosion, seismic, consolidation and bioturbation evaluations.
In 2000. EPA sponsored a pilot capping project to evaluate three methods of cap placement:
• Conventional placement (point dumping) by a hopper dredge with a split hull
• Spreading placement (slow-dump) by hopper dredge with a split hull moving through
the dump zone
• Direct pumpout through the drag arm of a hopper dredge
The direct pumpout method was not successful due to mechanical problems with the
equipment and was terminated after less than 300 m3 (400 yd3) of material was placed.
Approximately 92,625 m3 of cap material from a total of 92 loads was placed using the
conventional dump method. Approximately 10,325 m3 of cap material from a total 9 loads
was placed using the spreading (slow-dump) method. Material generated from the Queen's
Gate entrance channel project was used during the conventional placement methods, while
the material from a borrow site was used for the spreading method. Information collected
during the pilot capping project indicated that the spreading technique resulted in greater
uniformity and less disturbance to in-place effluent-affected sediments compared with the
point placement method (Fredette et al., 2002). There was not enough information to
evaluate the direct pumpout through the drag arm method.
4.3.5.2 Effectiveness
The 2000 pilot capping project evaluated three placement methods for a sand cap over three
45-acre (300 m x 600 m) cells and concluded that capping is a technically feasible option for
the site (Fredette et al., 2002). Monitoring during and after cap placement raised questions
about the effectiveness of capping in reducing surficial contaminant concentrations (SAIC,
2002). Monitoring equipment measured increases in turbidity as cap material hit the shelf
floor and created a surge wave. For the most successful cap, Cell LU at 40 m, the initial
drop of cap material created a vertical plume of suspended sediment 13 m thick and,
extending from the point of impact, an annulus with a radial dimension of approximately
220 m. However, both plume and annulus quickly decreased with distance and time. Point
dump of cap material on the deeper cell SU, produced a vertical plume 5 - 10 m thick and
an annulus with a radial dimension of 232 m. Increased turbidity, indicative of suspended
sediment, was measured 475 m from the point dump. A vertical plume 13 m thick was
measured at Cell LD, which was capped using the spreading technique; however, within 2
minutes plume thickness had decreased 50 percent (SAIC 2002). Turbidity associated with
the spreading technique dissipated faster than turbidity from point dump placement.
Post-cap monitoring revealed a depositional layer of fine-grained sediment over all three
caps. Two post-cap surveys were conducted. The first survey collected sediment cores
using a vibracore; the supplemental survey used a box core after concerns were raised that
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
the vibracore may have contributed to sediment scouring or drag down. Post-cap
monitoring found surface DDE concentrations lower than baseline (i.e., pre-capping) for
Cell LU, approximately the same for Cell LD, and comparable or higher than baseline
concentrations for Cell SU (SAIC 2002). The pilot project illustrated the potential difficulties
associated with capping soft sediment at 40 to 60 m depths.
The pilot capping project found the spreading method and the drag-arm method created less
of a shock wave and resulted in less disturbance to the effluent-affected sediment compared
with the point placement method. The spreading method is a relatively rapid placement
technique with a relatively minor modification to conventional methods. The mechanical
placement method using a clamshell bucket would be much slower and more costly than the
spreading method with a split-hull barge or hopper dredge; however, the impact of the
material would be much lower and disturbance of the effluent-affected sediment is expected
to be less. Low impact techniques are favored initially to minimize resuspension; however,
once the first layer is placed, more rapid methods could be employed. Precision placement
would be necessary around the outfalls to prevent clogging of the outfall diffuser ports and
around the shelf break to prevent mud flows.
4.3.5.3 Cost
The cost of precision placement techniques is much higher than more rapid techniques. The
size and depth of the deposit also increase the cost of this technique.
4.3.5.4 Screening Decision
Containment is retained for remedial alternative development.
4.3.6 Removal
Dredging and excavation are the two most common means of removing contaminated
sediment from a water body. Both methods require transporting the sediment to locations
for treatment and disposal. They also frequently include treatment of water from
dewatered sediment prior to discharge to an appropriate receiving water body. Some of the
key components to be evaluated when considering dredging as a cleanup method include
sediment removal, transport, staging, treatment and disposal.
The remedial technology associated with removal of the contaminated sediment from the
PV Shelf would consist of mechanical or hydraulic dredging. The dredged material would
require conveyance to a facility for offloading, treatment, and eventual disposal.
Resuspension management, residual management, and conveyance/transport technologies
are the associated processes included under the removal GRA.
As part of this FS, EPA tasked its contractor, Innovative Technical Solutions, Inc. to evaluate
removal methods for PV Shelf. Their assessment is included as Appendix F.
A complicating factor for this GRA is the need for precision in removing the layer of EA
sediment, which is approximately 60 cm thick. It would be easier to remove a greater
thickness of material; however, managing a larger volume of sediment and water would
significantly increase the cost of removal. The ability of the equipment to keep resuspension
of the contaminated sediment to a minimum is also important. The depth of the
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
contaminated material is beyond that normally associated with navigation dredging;
however, it is within the range of equipment used for mining. Technologies screened under
the removal GRA are as follows:
• Dredging
• Resuspension management
• Residual management
• Conveyance/transport
• Dredged material management
Dredging
Conventional dredging is broadly classified as mechanical or hydraulic. Mechanical
dredges use a device such as a clamshell or bucket to excavate the material. Material
removed is usually placed in barges for transport to a disposal site. Hydraulic dredges use
a centrifugal pump to create a vacuum on the intake side of the pump, where atmospheric
pressure then forces a sediment/water slurry into the suction pipe. Material is discharged
from the pump into a pipeline to another site, or can be pumped into barges or hoppers
contained within the dredge itself. A number of dredges use both principles, e.g., a cutter
suction dredge uses the mechanical action of a rotating cutter to dislodge sediment to make
it available to be lifted by the centrifugal pump. A third category of specialty dredges
includes pneumatic dredges, bottom crawling dredges, and others.
Hydraulic Dredges
Two hydraulic dredges, cutter suction and bucket wheel, do not work in depths greater than
30 m. Also, most of these types of dredges are not well suited for working in the open
ocean, i.e., they are limited in their ability to work in sea and swell. Plain suction dredges
can operate at depths of 100 m, however the accuracy of the plain suction dredge is poor as
it is difficult to leave a smooth bed and troughs are formed. Therefore, dredging a thin layer
would be difficult and positioning of the suction head would impose problems, effectively
eliminating them from further consideration. Trailing suction hopper dredges are much
better suited for work in the open ocean and can perform at the depths found on PV Shelf,
i.e., 50 to more than 100 m.
Trailing suction hopper dredges are ships with large bins or hoppers for holding slurry
brought to the surface by pumps operating through drag arms which terminate in drag
heads that contact the sea bottom. IHC Holland has fabricated hopper dredges capable of
dredging down to 100 m (328 feet) with a hopper capacity of approximately 20,000 m3
(26,160 yd3). However, due to the long drag arms, it may be difficult to position them
precisely. This would likely require additional overlap between passes to insure maximum
removal of the contaminated sediment. The additional overlap needed to eliminate the
furrowing impact would probably increase the amount of overdepth material dredged. The
suction dredge mixes sediment with water to create a slurry for conveyance through a
pipeline from the ocean bottom to the hopper. The solids content of the slurry would vary
depending on the sediment properties and site conditions, but typically would fall in the
range of approximately 8 to 20 percent solids by weight.
Mechanical Dredging
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Removal through mechanical dredging equipment would be performed using a mechanical
bucket, such as a clamshell. Sediment is removed at nearly in situ water content, and the
volume of water to manage is much less compared to hydraulic dredging. Therefore, the
volume of sediment is minimized, and there is less water to manage for disposal. The
primary advantage of the clamshell is that it can easily dredge down to 100 m with little or
no modifications because the bucket is deployed from a cable. Water depth is not a factor in
the ability to dredge other than production rate is reduced as depth increases. Special
buckets have been developed to reduce resuspension caused by the impact of the bucket on
the bottom and during ascent back up through the water column. Disadvantages of
mechanical methods include the potential for a loss of sediment in the water column during
the dredge cut cycle due to the physical disturbance of the mud bottom. Loss of sediment
also can occur during the removal cycle when bringing the bucket up through the water
column. Advances in the technology have minimized resuspension of sediment with the
advent of the cable arm or similar closed clamshell dredges. The design of the cable arm
provides the ability to control the vertical cut in the sediment.
Mechanical dredges require a material barge to contain the dredged material for transport to
an offload site. Sediment removed by mechanical dredging requires dewatering. The solids
content of material removed will be roughly equivalent to the in situ solids content (for PV
Shelf EA sediment, approximately 50 percent).
A trailing suction hopper dredge was determined to be the most appropriate for dredging
on the PV Shelf based on the water depth, dredge layer thickness, and sediment type. The
trailing suction hopper dredge is able to operate without any form of mooring or spud.
Dredging would require resuspension management, residual management, and
conveyance/transport of dredged material. Sediment resuspension during operation of
hydraulic dredges occurs when sediment dislodged by the dredgehead escapes the suction
pipe. Two important factors in resuspension for hydraulic dredges are the depth of the cut
and the speed of advance of the dredgehead. Sediment resuspension by hydraulic dredges
is typically more concentrated in the lower portion of the water column, where the
dredgehead encounters the sediment (USAGE, 2008). Suction dredges are given a high
rating in the USAGE guidance document, indicating that this dredge type is generally
suitable or favorable for sediment resuspension control. This is due to the fact that suction
dredges have no mechanical action at the dredgehead to dislodge sediment; therefore,
resuspension potential is due solely to the advance of the dredgehead through the sediment
(USAGE, 2008). When the hoppers on the dredge are full, there are several options for
conveyance of the dredged materials. The dredge can go to the disposal area and empty its
hopper; the dredged materials can be pumped through pipes directly to the disposal area; or
the dredged materials can be pumped into barges for transport to the disposal area.
Removal of the contaminated sediment would require the additional process option of
disposal. Once the contaminated sediment was removed, it would be necessary to manage
it by (1) placing it in a confined disposal facility (CDF) or contained aquatic disposal (CAD),
(2) disposing of it in the deep ocean, or (3) disposing of it in a landfill. Each of these options
is discussed below.
Confined Disposal Facility
The CDF approach involves placing dredged sediments in a diked structure in order to
isolate the contaminants from the environment. The CDF must be designed to effectively
contain contaminants. Effluent discharge may require controls such as chemical flocculants
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
and/or filtration to meet water quality standards. A surface cover of clean material may be
required for purposes of isolation of the contaminated material and would assist in control
of leachate releases. Monitoring to include effluent discharge, wells, and air quality stations
would be necessary during and following initial construction of a CDF and placement of
material. Water is discharged over a weir structure or allowed to migrate through the dike
walls while sediment remains in the CDF (EPA, 2005). Long-term monitoring would be
necessary to ensure that contaminants were not discharging from the CDF. Because much of
the sediment at the PV Shelf Study Area exceeds the hazardous waste criterion for DDTs,
the CDF would have to be located onsite or an offsite location would need to be permitted as
a hazardous waste disposal facility. CDFs typically are constructed in shallow water and
are not proven in water that is hundreds of feet deep. Onsite construction is not feasible; for
example, the diked walls of a CDF at 60-m depth would need to be several hundred feet
wide at the base.
Contained Aquatic Disposal
The CAD approach involves placing dredged material in a structure consisting of a
constructed or natural depression in the sea floor with a submarine cap. The design
objective of the CAD is similar to a CDF: isolation of contaminated sediments from the
environment. A CAD cell would be constructed by first constructing stone dikes similar to
the lower portion of dikes needed for a CDF. Contaminated sediment would be deposited
in the cell and capped. Potential impacts to the dredging site and requirements for long-
term monitoring are also similar to those associated with the CDF. Because this technology
involves dredging and placement of the dredged material prior to placing a cap, it offers
few advantages over containment.
Implementation is difficult because it requires removal of the material through dredging
and cap placement. In addition, similar to a CDF, because much of the sediment at the PV
Shelf Study Area exceeds the hazardous waste criterion for DDTs, the CAD would have to
be located onsite, or an offsite location would need to be permitted as a hazardous waste
disposal facility. It is unlikely that such a facility would receive regulatory approval.
Deep Ocean Disposal
Ocean disposal of dredged sediments consists of placing sediments in deep basins offshore
from the PV Shelf. The rationale for this option is that circulation at depths below the basin
sill is very restricted and dissolved oxygen concentrations, and hence biological activity, are
generally low. Therefore, the potential risks associated with waste disposal in the basins
also are relatively low. In addition, basins have been used in the past for disposal of DDT
wastes (Venkatesan et al., 1996). Regardless, ocean disposal of dredged sediments would
require formal designation of an ocean dredged material disposal site according to the
Marine Protection Research and Sanctuaries Act (MPRSA). Given the concentrations of
DDTs and PCBs in the sediments, material dredged from the PV Shelf Study Area would
likely fail toxicity and bioaccumulation suitability tests for ocean disposal required under
federal law. Ocean disposal of the effluent-affected sediment from the PV Shelf would not
be allowed (personal communication Ross, 2007).
Offsite Landfill
Disposal of dredged sediments at a permitted upland site would be effective at reducing
risks to the marine ecosystem. However, pretreatment of sediments prior to disposal would
be required to reduce the water content. Under California law, much of the contaminated
sediment would require treatment to reduce contaminant concentrations before it would be
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eligible for disposal in a hazardous waste landfill. The proven technology for destruction of
DDTs and PCBs is incineration.
4.3.6.1 Implementability
The implementability of dredging in deep water is difficult. Removal would cause
resuspension of the effluent-affected sediment. The dragline of a trailing suction hopper
dredge is difficult to control at depth, especially under ocean currents. The required cycle
time for the depth of the contaminated sediments would cause low production rates for
dredging of significant volumes.
The dredged sediment would undergo initial dewatering by gravity flow and then
solidification before it could be treated. Treatment of water generated as a result of
dredging and dewatering would be required as well. Pilot studies would be required to
ensure that performance standards for water quality and sediment disposal are achievable.
The proposed unloading areas for dewatering would be within the Ports of Los Angeles and
Long Beach, approximately five nautical miles from the Shelf. Transportation to the
proposed unloading areas could cause issues with ship traffic due to the location within the
ports.
4.3.6.2 Effectiveness
The effectiveness of this technology is moderate. Hydraulic and mechanical dredging are
proven technologies for removal of ocean sediment but are rarely done at these depths. The
volumes of dredged material would slow operations as the hopper dredge or barge would
need to be emptied frequently. Resuspension of sediment would occur with each dredge
cycle. The volumes of dredged material would be difficult to manage, resulting in frequent
interruption of operations. The amount of EA sediment mobilized by dredging would be
significant. The volume of water requiring collection and treatment would impact operations
and would require construction of a water treatment plant.
4.3.6.3 Cost
The cost of this technology is high due to the amount of sediment and water that would
need to be managed and disposed. Dredging would result in the need to treat tens of
millions of gallons of water per day. In addition, a feasible disposal option for the dredged
material would need to be developed. The EPA Office of Water has indicated that ocean
disposal of the effluent-affected sediment from the PV Shelf would not be allowed (Ross,
2007). Therefore, the dredged material would require disposal at a hazardous waste
disposal facility or construction of an in-water CDF. Either action would require
construction of a waste treatment facility to meet hazardous waste disposal standards.
Attaining regulatory approval for an in-water disposal facility is unlikely. Even if a facility
were permitted, treatment and disposal would add millions to the cost of remediation.
4.3.6.4 Screening Decision
Removal with treatment and disposal is retained for remedial alternative development.
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
4.3.7 Ex Situ Treatment
Ex situ treatment options were considered for removal of DDTs and PCBs from PV Shelf
sediments. In general, treatment technologies are designed to reduce the toxicity, mobility,
and volume of contaminated material.
Ex situ treatment technologies require sediment removal (i.e., dredging), generally followed
by dewatering of the sediment and treatment of both the dewatered sediment and water.
This approach requires treatment application in a nearby confined facility where technologies
use physical, chemical, biological, and thermal processes to remove contaminants from the
sediment. Ex situ treatment technologies are evaluated as a category below.
4.3.7.1 Implementability
Implementation of ex situ treatment is not feasible because of the need to dredge, dewater,
transport, and treat the sediment, and dispose of treatment residuals. Removal also would
cause resuspension of the effluent-affected sediment, which would be difficult to manage.
4.3.7.2 Effectiveness
Ex situ treatment using thermal treatment (incineration) or solidification can be an effective
method to destroy or immobilize DDTs and PCBs in sediment after it is dredged.
Construction of a thermal treatment plant would encounter the same difficulties discussed
under removal. Other ex situ treatment technologies are generally less effective. This
treatment would require dredging and its associated process options. Significant
resuspension of contaminated sediment will occur when the sediment is dredged prior to
treatment. The overall effectiveness is considered low.
4.3.7.3 Cost
The cost of this technology is high due to the need for dredging, transport, dewatering, and
treatment of dredged sediments. A treatment facility would need to be constructed solely to
treat sediment from the PV Shelf Study Area, which is estimated to be approximately
3,610,000 cubic yards after dewatering.
4.3.7.4 Screening Decision
Ex situ treatment technologies were rejected for alternative development because it would
be difficult to implement successfully. Ex situ treatment would require dredging,
resuspension management, residual management, transport and dewatering of dredged
material, construction of dewatering and/ or storage facilities as well as a treatment plant.
4.3.8 In Situ Treatment
In situ treatment technologies are conducted with the sediment in place. The advantage is
that dredge removal of the sediment is not required. In situ sediment treatment
technologies use physical, chemical, biological, and thermal processes to remove
contaminants from the sediment. However, in situ treatments usually require more time
than ex situ treatments, and achieving a uniform treatment is more difficult than with ex
situ treatment.
In situ chemical treatments (for example, persulfate or iron/hydrogen peroxide [
are designed to either chemically destroy or reduce the toxicity of the contaminants. In situ
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
chemical treatment may be carried out alone or in conjunction with biological treatment.
Current research has not identified a chemical additive that destroys DDTs. In theory,
biological treatment can destroy (e.g., complete conversion to carbon dioxide [CC>2] or
methane) or reduce the toxicity of both DDTs and PCBs. Success is dependent on such
factors as sediment redox conditions, pH, microbial communities present, and
concentrations of microbial nutrients. Reductive dechlorination of DDE to DDMU and
other daughter products is occurring at the site. The microbial processes and environmental
conditions that are allowing this to occur are currently being investigated.
4.3.8.1 Implementability
The delivery or injection and mixing of substrates into the sediment would be difficult in
deep water. In addition, the mechanisms influencing degradation are not well understood.
Until the processes driving degradation are identified, there is no way to know if the
mechanisms that biologically breakdown the contaminants can be controlled or accelerated.
4.3.8.2 Effectiveness
The effectiveness of chemical oxidation is unproven for the COCs in ocean sediments in the
water depths present at the PV Shelf Study Area. Delivering and mixing oxidation chemical
into the sediment and achieving uniform treatment success over a large area on the ocean
floor at 50 to 100 m is unlikely.
Research indicates that biochemical degradation of DDE is occurring at the site and could be
a significant mechanism for natural recovery. However, the mechanism by which this is
occurring is not known. Even if the microbial process(es) driving the degradation were
identified, delivering or injecting and mixing nutrients or microbes into the sediment and
achieving uniform treatment success over a large area on the ocean floor at 50 to 100 m is
difficult.
No native biological degradation of PCBs has been observed at the site. Because the process
is not naturally occurring, any biological treatment approach for PCBs will require finding
microbes that could breakdown the PCBs in the effluent-affected sediment and identifying
appropriate nutrients, plus the addition of nutrients and/or microbes to the sediment.
Laboratory treatability testing or pilot testing would be necessary to test this approach.
However, even if microbial agents could be identified, their success in situ is not guaranteed.
Conversely, biological degradation of DDE at the PV Shelf is thought to be occurring under
natural conditions. While there is still much that is unknown about this process, including
the relative toxicity of the final degradation product, additional monitoring of sediment
characteristics at the site (for example, redox potential [Eh], sulfate, TOC) may provide
information on controlling factors needed to allow for laboratory and pilot testing of
bioaugmentation strategies for the treatment of DDE and related organochlorine
compounds.
4.3.8.3 Cost
The cost for in situ biological treatment would be high because this technology requires more
research and understanding before implementation. Even if the mechanisms driving
reductive dechlorination were understood, the cost to deliver nutrients or other materials
over a large area at depth could be high.
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4. GENERAL RESPONSE ACTIONS AND REMEDIAL TECHNOLOGIES
4.3.8.4 Screening Decision
Due to the difficulties in delivering and mixing nutrients or microbes, the limited
understanding of the degradation processes, and the limited ability to modify conditions to
enhance degradation, in situ treatment is rejected for remedial alternative development.
4.4 Summary of Retained Technologies
Institutional controls, MNR (monitored natural recovery), containment, and removal were
retained for alternative development. A summary of each technology is provided below:
• Institutional controls are retained for alternative development and consist of public
outreach and education, enforcement, and fish monitoring.
• MNR is retained and uses ongoing, naturally occurring processes to contain, destroy, or
otherwise reduce the bioavailability or toxicity of contaminants in sediment.
• Containment with a sand cap is retained and consists of capping all or part of the
contaminated sediment to limit the mobility of the contamination and reduce the
potential for fish exposure to contaminated materials. Other retained technologies to be
used in conjunction with containment are resuspension management, residual
management, and material transport/conveyance using barges.
• Removal with a hydraulic suction hopper dredge or mechanical clamshell dredge is
retained. Dredging of all or part of the contaminated sediment would include
dewatering, treatment and disposal.
These remedial technologies may be used alone or in combination to achieve the RAOs for
the site. In Section 5.0, these technologies are assembled into site-specific remedial
alternatives and initially screened for implementability, effectiveness, and cost.
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5.0 Development and Screening of Alternatives
5.1 Introduction
In accordance with EPA's Guidance for Conducting Remedial Investigations and Feasibility
Studies Under CERCLA (USEPA, 19883), remedial action alternatives are developed by
assembling the remedial technologies and representative process options that were
identified and screened in Section 4.0. This section presents remedial action alternatives
that have been developed to manage the waste found on the PV Shelf that poses an
unacceptable risk to human health and the environment. These alternatives vary primarily
in the extent of active remediation and reliance on long-term management of residuals and
untreated wastes.
The objective of alternative development is to provide an appropriate range of alternatives
and sufficient information to analyze and compare adequately the alternatives in Section
6.0, Detailed Analysis of Remedial Alternatives. The results of the detailed analysis will be
presented to decisionmakers for use during the remedy selection process.
During preparation of the feasibility study it became apparent that additional studies will be
necessary during the remedial design phase to quantify risk reduction and assess remedy
effectiveness more accurately. Therefore, EPA will select one of the alternatives presented
in Section 6.0 as an interim remedial action. After the first Five-Year Review, EPA will
prepare a final record of decision, detailing any additional actions it deems necessary to
reach the site remedial action objectives.
This section assembles and screens five alternatives. Section 5.2 presents the assembled
alternatives and an overview of the alternative components. In the additional subsections
the components of the alternatives are described and developed in detail. The names of the
remedial alternatives highlight the major components or elements of each alternative.
Specific conceptual design or component details were developed for the cost, evaluation,
and comparison of alternatives only, and are not meant to serve as a true design or specific
recommendation of technologies or process options. In Section 5.2, the alternatives are
screened for effectiveness, implementability and cost. The most promising alternatives are
selected for detailed analysis in Section 6.0.
5.2 Alternative Development
Five alternatives were assembled by combining GRAs and the process options chosen to
represent the various technology types. Alternative 1 is the no action alternative.
Alternative 2 consists of institutional controls (ICs) and monitored natural recovery (MNR).
Alternative 3 consists of institutional controls (ICs) and a small subaqueous cap to enhance
monitored natural recovery (MNR). Alternative 4 consists of containment, i.e., placement of
a subaqueous cap over the area of most contaminated sediment, plus ICs and MNR for
those areas of PV Shelf that are not capped. Alternative 5 is a removal alternative, hydraulic
dredging of the most contaminated sediment, with treatment and disposal onshore. The
alternatives are identified as follows:
/MAY09PVS CHART 5.DOC 5-1
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
• Alternative 1 — No Action
• Alternative 2 — Institutional Controls (ICs) & Monitored Natural Recovery (MNR)
• Alternative 3 — Containment (small cap) with ICs and MNR
• Alternative 4 — Containment (large cap) with ICs and MNR
• Alternative 5 — Removal (dredging) with ICs and MNR
5.2.1 Alternative 1— No Action
Alternative \, a "no action" alternative is required by the NCP as a baseline for comparison
with other remedial action alternatives. No additional attempt is made to satisfy the RAOs,
and no remedial measures are implemented. Consequently, the no action alternative does
not include active remediation, monitoring, or institutional controls. Under the no action
alternative, existing institutional controls are not considered.
5.2.2 Alternative 2—Institutional Controls and Monitored Natural Recovery
Alternative 2 is intended to reduce risks to human health associated with the consumption
of contaminated fish from the PV Shelf Study Area through nonengineered controls.
Institutional controls have been in place at the PV Shelf Study Area since fish advisories and
health warnings were first issued in 1985. EPA's current institutional controls program
consists of three components: public outreach and education, enforcement, and monitoring.
As part of Alternative 2, EPA's current institutional controls program would continue, but
would be modified as needed to increase effectiveness. Like the current institutional
controls program, the future institutional controls program would rely heavily on
partnerships with other federal, state, and local agencies. For example, the California-EPA
Office of Environmental Health Hazard Assessment (OEHHA) will contribute technical
expertise for the updated advisory based on results from the ocean fish monitoring
program, and will serve on the Technical Review Board for the public outreach and
education component of the institutional controls program. The enforcement component of
the institutional controls would be carried out through the CD EG. For more detailed
information on the ICs program, the reader is directed to Appendix D: Palos Verdes Shelf
Superfund Site Institutional Controls Program Implementation Plan.
5.2.2.1 Public Outreach and Education
EPA created the Fish Contamination Education Collaborative (FCEC) to bring together
interested agencies, associations, and community-based organizations to design and
implement an outreach program to address the health risks from eating contaminated fish
related to the PV Shelf Study Area. The public outreach and education program conducts
outreach to anglers and the general community.
The angler outreach program focuses on educating anglers in Los Angeles and
Orange Counties about fish contamination, fish advisories, identification of contaminated
fish species, and safer fish consumption practices. Currently, this outreach has been
conducted at bait shops and eight piers: Belmont, Cabrillo, Pier J, Seal Beach, Santa Monica,
Hermosa, Redondo, and Venice. Future outreach for anglers may include different areas if
warranted to increase effectiveness.
Current angler outreach consists of a 4-hour session at each pier four times a week (twice
during the week and twice on weekends). For this alternative, the same level of outreach is
assumed for the next ten years. At the first Five-Year Review, the outreach program would
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
be reassessed based on fish data and angler awareness. Based on fish data, the message on
safe eating habits could be revised, or fishing locations could be added or deleted. If it
appears the same level of effort is necessary, the four times a week program would continue.
The community outreach program includes outreach to the general population, specific
ethnic groups, and commercial fish market owners. Outreach to the general population
and specific ethnic groups focuses on educating people about the potential health risks of
eating fish from the PV Shelf Study Area and on safer fish consumption practices.
This program partners with health fairs, community fairs, and local health departments to
provide educational materials and training. Outreach to commercial fish market owners is
conducted to educate owners about the dangers of buying fish from unlicensed dealers who
may be catching fish from restricted areas.
For Alternative 2, community outreach would involve using a combination of state and local
health department services, community-based organizations, or community relations
specialists for outreach to the general community and sensitive populations such as certain
ethnic groups or women of child-bearing age. The outreach would include working with
community-based organizations and media to educate people on behaviors to reduce the
risk of eating fish with elevated levels of DDT and PCBs. A feedback component to gauge
behavior changes from the information and education program would be included to help
determine the program's success.
Based on the Consumption, Attitude, Behavior Study (CABS) survey conducted by the FCEC
in 2007 (FCEC Year IV-V Report), women of child-bearing age are much more aware of the
fish contamination related to mercury than the local fish contamination issues related to the
PV Shelf. The CABS also showed the population at the most risk, (i.e., consumption pattern
including frequencies, fish parts eaten, type of fish) are Asian, including Chinese, Vietnamese
and Filipino. The market monitoring data reflect the same community profile in terms of
where white croaker are available for purchase. The future FCEC program will include
specifically targetting the populations at most risk.
Specific training and outreach materials already have been developed, but would be revised
as needed to increase effectiveness. The public outreach and education program includes
surveys of the different groups to identify the preferred method of information delivery and
to assess changes in behavior resulting in risk reduction. All components of the outreach
program have been and would continue to be conducted in several languages that are spoken
in Los Angeles and Orange Counties; the outreach efforts have been conducted in numerous
languages including English, Spanish, Cambodian, Chinese, Filipino, Korean, Vietnamese,
Chamorro, Samoan, Marshallese, and Tongan.
The cost for the community outreach is based on the current level of effort for the existing
institutional controls program. It is assumed that the same level of effort would continue for
the next ten years. The first five-year review would be used to assess the program's
effectiveness and plan for any changes in outreach locations and messages to be included in
the final remedy. It is anticipated the level of effort would be reduced over time.
5.2.2.2 Enforcement
The enforcement program focuses on existing commercial and recreational restrictions on
fishing for white croaker established by CDFG to help prevent white croaker with elevated
levels of DDT and PCBs from being caught and sold. In 1995, the CDFG closed part of the
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
PV Shelf for commercial catch of white croaker because of the elevated DDTs and PCBs
found in the area; Figure 5-1 shows the location of the area closed for white croaker
commercial fishing. In March 1998, in response to concerns about white croaker being
illegally sold by sport fishermen to commercial fish markets, CDFG revised the white
croaker recreational catch limit from unlimited to 10 fish per day.
Current enforcement and monitoring of commercial and recreational fishing at the PV Shelf
and adjacent areas is under the jurisdiction of CDFG. The current enforcement program
includes periodic inspections by CDFG of the commercial catch ban area during routine
patrols and limited shore-based inspections and spot checks at locations where commercial
fishermen are expected to return. CDFG also provides EPA with regular documentation
describing the results of inspections.
The sport fishing restriction enforcement program has included limited, random inspections
of sport fishers' white croaker catch at locations presumed to be within the area where fish
are impacted by PV Shelf. Unlike the commercial fishing ban, the sport fishing restriction is
not limited to any specific area. Thus, for the future sport fishing restriction enforcement
program, the potential areas to be covered could range from Long Beach Harbor to the
north side of Santa Monica Bay.
Alternative 2 would increase the enforcement program close to the source. Based on CDFG
landing information, 27,358 and 27,538 pounds of white croaker were landed from catch
blocks 719 and 740 in 2006 and 2007, respectively (CDFG, 2008). Greater than 90 percent of
the white croaker were landed at Terminal Island and Huntington Beach. However, its
availability was scarce in local fish markets (2004 EPA market fish sampling). This
discrepancy between the reported landed catch vs. actual availability in markets raises
questions about other outlets for white croaker. Due to various constraints (legal and
others), EPA was unable to obtain the white croaker "landing to markets" pathway
information to fill the informational gap. This information is critical for EPA and
appropriate agencies to better characterize the potential risks associated with eating
contaminated white croakers and design/implement an effective enforcement program that
will stop contaminated fish from reaching consumers. EPA and the appropriate State and
local agencies are working to identify appropriate water-based and shore-based
enforcement tools to address this data gap. Monitoring closer to the source, e.g., of
wholesalers and/or commercial fishing fleet, would help clarify the ocean-to-consumer
pathway.
Alternative 2 assumes increased enforcement/monitoring in coordination with State and
local agencies. A more detailed description of the ongoing ICs program is included as
Appendix D.
5.2.2.3 Monitoring for ICs Program
The current monitoring program includes collection of white croaker at designated locations
in the PV Shelf Study Area (ocean monitoring) and at local markets (market monitoring).
5-4 MAY09PVS CHART 5.DOC
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
Sjanta Monica Bay
Los Angeles
701
Redondo Beach
Palos Verdes
Peninsula
Long Beach
718
San Pedro Bay
KEY
Palos Verdes Shelf
719 CDFG catch blocks
Commercial no-take zone
for white croaker
Figure 5-1: Location of CDFG white croaker commercial catch ban area. Note catch blocks
included in banned area.
/MAY09PVS CHART 5.DOC
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
The purpose of the ocean monitoring is to assess whether the boundaries of the commercial
fishing ban are adequate or may need to be expanded and whether recreational anglers are
catching fish with elevated levels of DDT and PCBs at popular fishing locations. The
purpose of the market monitoring is to evaluate if contaminated white croaker from the PV
Shelf Study Area are reaching local consumers and to determine the source of white croaker
with high levels of contaminants found in those establishments.
Market Monitoring
In 2004 and 2005, EPA visited 68 markets a total of 135 times and found only 6 markets that
carried white croaker (30 fish total). However, white croaker from these six markets
included fish with high concentrations of DDTs and PCBs. It is not known whether the
presence of these white croaker in retail establishments is due to violations of the PV Shelf
commercial fishing ban, inadequacies of the catch ban area, sport fishers illegally selling
croaker to retail establishments, or other factors.
From 2005 to 2006, 45 Los Angeles County Department of Public Health Environmental
Health (LADPH-EH) inspectors who were trained by the FCEC program inspected 470
independent fish markets/wholesalers in Los Angeles County. White croaker were found
at two markets. In 2005, City of Long Beach Environmental Health (LB-EH) inspectors
inspected 46 non-chain markets; only one market carried white croaker and that market
could not produce receipts/invoice. More recently, in 2009, CDFG wardens inspected a Los
Angeles County market and found 100 Ibs. of white croaker that the market could not
produce receipts/in voice.
With the available market monitoring results, in September 2006, EPA contacted the Orange
County Health Care Agency Environmental Health (OCEH). OCEH and EPA established a
draft work plan and budget to conduct monthly inspect of white croaker at targeted markets
in Orange County. Orange County joined Los Angeles County and the City of Long Beach
environmental health departments in conducting inspections at selected markets
throughout the year, starting in 2008.
The future market monitoring program will involve continued monitoring of white croaker
in local markets. The City of Long Beach and Los Angeles and Orange counties
environmental health inspection agencies will assist by reporting the presence of white
croaker in markets for sample collection, and tracking supplier sources for white croaker
found in the markets. Approximately 250 total visits will be made annually to 55 different
markets in Los Angeles County, Long Beach or Orange County. The market visits will be
based on the frequency of health department inspections to markets identified in the
previous sampling effort as most likely to carry white croaker. Based on previous results, it
is assumed that white croaker will be found at approximately 10 of the 250 markets visits,
and that 5 white croaker will be collected from each market. Therefore, up to 50 white
croaker may be collected annually and analyzed for DDTs and PCBs.
Ocean Fish Monitoring
The future ocean monitoring program would consist of sampling fish from different areas of
the PV Shelf to track contaminant concentrations for public outreach efforts and to ensure
the boundaries of the catch ban area are current. The sampling program would build on the
EPA-MSRP 2002-2004 Fish in Ocean Survey (USEPA/MSRP, 2007) and EPA directive Using
Fish Tissue Data to Monitor Remedy Effectiveness (USEPA, 2008). The ICs component of the
ocean monitoring would consist of verifying the catch ban area boundaries by analyzing
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
samples of white croaker from designated sample locations in the PV Shelf Commercial
Catch Ban Area for DDTs and PCBs as part of the five-year review.
Sampling also would be conducted biennially from popular fishing piers located in
Los Angeles and Orange counties. It is assumed that 10 white croaker would be collected
from half of the piers (i.e., 4 piers) every year, for a total of 40 white croaker analyzed for
DDTs and PCBs. Additional species also may be included in the pier sampling if warranted
based on revised fishing advisories.
5.2.2.4 Monitoring for Natural Recovery
Alternative 2 relies on an aggressive ICs program to control human health risk from
consumption of fish with unacceptable levels of COCs. The monitored natural recovery
(MNR) component of the alternative tracks reduction of COCs in sediment, water and fish
to verify achievement of RAOs. Monitoring will be conducted initially to establish a
baseline (Year I), then five years after remedial action for the five-year review.
MNR would also include studies to learn more about the recovery processes. Specifically,
MNR includes toxicity assessments of DDMU and DBF. DDMU is a prevalent daughter
product of DDE and could be the most common DDT breakdown product in the sediment
besides DDE. DBF has been identified in the sediment as well. As the final breakdown
product of DDT, knowledge of DBF's toxicity is important to understand the ultimate fate of
the EA sediment. Unlike DDT, there is no evidence that PCBs are breaking down in the EA
sediment deposit. Additional analysis of sediment transport and contaminant flux from the
EA sediment is underway and will help shape the final remedy. Another study that would
be undertaken as part of MNR is a white croaker tracking study that would provide
information on white croaker feeding patterns and preferred PV Shelf locations.
EPA's trend monitoring would include:
• Coring of sediment throughout the PV Shelf Study Area to assess vertical distribution
and mass of contaminants
• Sampling of contaminant concentrations in pore water and the water column
• Fish sampling
Data collected for the five-year review will be used in the development of the final record of
decision. At that time, the monitoring program will be reassessed to determine if there are
elements that should be dropped or changed, for example, sediment sampling locations or
specific fish species.
Biological Monitoring
Progress toward reaching RAOs will be measured by monitoring fish across the PV Shelf
Study Area. The monitoring program will be based on the segments established under the
2002/2004 Contaminant Fish Survey and will follow the Fish Survey sampling plan for fish
analysis. EPA will develop the monitoring program in consultation with those agencies that
collect and/or use fish data to maximize the utility of the monitoring. Contaminant data on
local benthic-feeding fish, e.g., white croaker, as well as pelagic forage fish, e.g., Pacific
sardine, will be collected.
Sediment Monitoring
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
In order to maximize the utility of the sediment sampling program, it will use the LACSD
sampling station grid, shown in Figure 1-4 for baseline monitoring. Sediment cores will be
collected at 30 LACSD sampling stations (transects 1 through 10) along the 30-, 60-, and 150-
m depth contours. Duplicate cores will be taken at selected stations along the 60- and 150-m
isobaths, for a total of 50 sediment cores. The contaminant mass and vertical distribution
will be evaluated in each core by analyzing 4-cm segments from the surface to the end of the
core. Sediment will be analyzed for grain size, TOC, DDTs, and PCB congeners. DDT
breakdown products, DDMU, DDNU, and DBF will be included in the analysis. Final data
products will include mass estimates of DDTs and PCBs and their metabolites and
congeners.
Water Monitoring
Contaminant concentrations in the water column, including suspended particles, have not
been routinely monitored over the PV Shelf Study Area. Waterborne contaminants may be
assimilated into the food chain by suspended-particle-feeding biota and by chemical
exchange and adsorption on respiratory membranes (e.g., gill surfaces). Studies conducted
over the PV Shelf in 1997 indicated significantly elevated water column concentrations of
DDTs and PCBs in bottom waters where demersal fish populations reside, including white
croaker and Dover sole (Zeng et al., 1999). Concentrations of DDTs in water at the site
exceed EPA AWQC for saltwater aquatic life (1 ng/L) and for human health (0.22 ng/L).
Concentrations of PCBs exceed EPA AWQC for human health (0.064 ng/L), but not for
saltwater aquatic life (30 ng/L).
To analyze water samples for COCs at such low concentrations requires special sampling
equipment. Examples of sampling systems that are able to analyze COCs at these ultra-low
levels include water pump and filtration system and solid phase micro-extraction (SPME)
samplers. EPA has used polyethylene samplers to analyze low levels of PCBs in water
bodies and is currently testing their utility on PV Shelf. EPA will use passive samplers to
monitor water column contaminant concentrations. Samplers will be deployed at the same
30 stations discussed above. Three samplers per location will measure COCs at 3 meters
above the seabed, mid-column, and 5 meters below the water surface.
5.2.3 Alternative 3—Small Cap with MNR and ICs
Under this alternative, the ICs program and MNR, as described above, will continue.
However, in addition to the sediment-water-fish monitoring described under Alternative 2,
this alternative would accelerate natural recovery by adding a small cap of clean sediment
over an area near the outfalls where surface concentrations of DDTs are highest. The
objectives of small cap/enhanced MNR are to bury the contaminated sediment under clean
sand, to block further erosion and to limit contaminant flux or transport from this "hot spot"
(Figure 5-2).
Development of Cell Grid
The PV Shelf Study Area was divided into cells based on the LACSD sampling stations
(Figure 1-4). An attempt was made to determine the total mass of contaminants present in
each grid cell across the full sediment profile. While data are not available on concentrations
of DDTs and PCBs at depth across the entire PV Shelf Study Area, surface (0 to 2 cm)
sediment data are available from LACSD's 2002 and 2004 sampling events. These data were
used to estimate contaminant mass in surface sediments for each of the 33 cells created by the
grid of the PV Shelf Study Area. This method does not accurately reflect the extent of
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
contaminated sediment because it does not include the full depth of the EA deposit.
However, surface concentrations tend to correlate to concentrations at depth across the 60-m
contour. The grid allows rough quantification of contaminant mass by area, which is
necessary to develop capping or dredging alternatives. If an alternative that includes active
remediation is selected, additional sediment characterization will be necessary as part of the
remedial design. Based on the grid, approximately 1.3 km2, or 320 acres, would be included
in Grid Cell 8C, the locus of the "hot spot."
5.2.3.1 Area to be Covered
The 8C "hot spot" has the highest concentrations of DDTs in the surface sediment of the PV
Shelf. Figure 5-2 shows the proposed area to be covered: Grid Cell 8C. The total area of
Grid Cell 8C is 1.3 km2, which is equivalent to approximately 1.6 percent of the total area of
the PV Shelf. The total mass of DDTs in surface sediment inside the 8C grid boundary is
estimated to be 2,250 kg, accounting for approximately 44 percent of the total mass of DDTs
in PV Shelf surface sediment. The total mass of PCBs present in surface sediment in Cell 8C
is an estimated 85 kg, accounting for 13 percent of the total mass of PCBs in surface
sediment. The 8C area is also where the deposit is thickest and contains the highest
concentration of contaminants at depth.
5.2.3.2 Enhancement Objectives and Design
While contaminant concentrations have dropped overall, in the vicinity of the Y outfall they
have shown little change. Figure 5-3 shows DDE concentrations in sediment cores taken at
the outfall over time. The surface concentrations have increased, and the effluent-affected
sediment deposit appears to be moving upward. Recent analysis of PV Shelf (Noble, et al.,
2008) indicates the ocean velocities are greatest at both ends of the shelf, and smallest
around the outfalls. Although the internal waves and currents are weaker in the area
between the outfalls, it is estimated to be erosive because of the characteristics of the
sediment and lack of a source of new sediment (Ferre and Sherwood, 2008). The apparent
erosion between the outfalls is minimal, i.e., 0.1 to 0.3 mm/yr; however, without a source of
new material, the analysis indicates the EA sediment deposit in this area will slowly erode
(Ferre and Sherwood, 2008). Alternative 3 would add clean sediment to approximately 320
acres. Oceanographic data collected during Winter 2007-08 will be used to assist in selection
and design of material placement.
Placement of a sand cap normally accelerates natural recovery by adding a layer of clean
material over contaminated sediment. The acceleration can occur through several processes,
including increased dilution through bioturbation of clean sediment mixed with underlying
contaminants. The target thickness for the cover would be 30 to 45 cm. The sediment
source would be selected to meet specific geotechnical properties, such as grain size and
density, organic content, and settling velocity. It would be designed to be thick enough to
prevent advection of pore water through the material, temporarily eliminate benthic
organisms, and allow for some spreading during and after placement until consolidation
and compaction solidifies the cap material.
5-10 MAY09PVSCHAPT5.DOC
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
Palos Verdes Peninsula
Pacific Ocean
-600
WCSO - SanluBon OtaMoi of Us *«8des Couniy
1. kflhalfK arr in TTIH«TV
c St* (Miles]
Fusibility Study/Record of Decision Support
Palos Verdes Shelf
Lot Angeles County, California
FIGURES .2
Grid (Ml 8C layout
/MAY09PVS CHART 5.DOC
5-11
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
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5-12 MAY09PVSCHAPT5.DOC
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
8 S S S
I
I
Figure 5-3: Sediment Cores at LACSD Station 8C
/MAY09PVS CHART 5.DOC
5-13
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
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5-14 MAY09PVSCHAPT5.DOC
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
Material and Placement
Placement of the sand cover would require similar technologies as cap construction,
discussed under Alternative 4. Specifically, resuspension management, residual
management material conveyance and transport would be the same as Alternative 4.
Because the "hot spot" is between the outfall pipes, low-impact placement techniques
would be used. U.S. Army Corps of Engineers (USAGE) research on placement techniques
and sand/sediment parameters for PV Shelf (Palermo et al., 1999, Guiliani, 2004) as well as
lessons learned from the pilot capping project will assist in determining the most effective
method to cover the hot spot with minimal resuspension. An advantage to material
placement in this area is that it abuts relatively clean sediment, i.e., the area includes the
southern edge of the deposit. Thus, placement would begin at the southeast edge, moving
to deeper waters to the northwest.
Construction would require studies to determine the most effective techniques; however,
low-impact techniques, i.e., submerged diffuser (e.g., tremie tube with a diffuser spoon)
would be assessed during remedial design. After placement of the initial layer, faster
placement by spreading or casting can be used. The volume of material required to cover
8C is estimated to be 660,000 m3 or 864,000 cubic yards (yd3), with a 10 percent loss
allowance.
5.2.3.3 Monitoring
Cap construction monitoring would follow EPA guidance on performance monitoring
(USEPA, 2005). Monitoring would track the areal extent and thickness of the cover during
construction as well as surface sediment resuspension. The intent of the cover is to stabilize
sediment and reduce surface concentrations. Longterm monitoring would measure
contaminant flux off the cap as well as the remaining thickness of the cover. The assessment
of capping (Appendix E) estimates that a 45-cm cap would begin to see recolonization of
surface sediment by benthic invertebrates within a year, and that some of the buried EA
sediment may be mixed with surficial sediment over time. Sediment monitoring, as
described under MNR (i.e., sediment cores across the Shelf to assess vertical distribution
and mass of COCs) would indicate whether the clean sediment has reduced surface
concentrations of COCs and formed a protective layer, or if there are breaches in the cap.
Analysis of sediment cores would also track reductive dechlorination at depth, as discussed
in section 5.2.2.4. Additionally, under this alternative, EPA would investigate the processes
that drive the reductive dechlorination of DDE with the goal of assessing rates of
transformation, identifying end products, and determining whether this natural process can
be enhanced.
5.2.3.4 Institutional Controls
The institutional controls and other monitored natural recovery program elements for
Alternative 3 are described under Alternative 2.
5.2.4 Alternative 4—Containment with Institutional Controls and Monitored
Natural Recovery
Alternative 4 — Containment with Institutional Controls (ICs) and Monitored Natural
Recovery (MNR) consists of placing an in situ, subaqueous cap over the areas of the EA
/MAY09PVS CHART 5.DOC 5-15
-------
5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
sediment deposit that contain the highest contaminant concentrations on the surface and at
depth, implementing MNR over those areas not capped, while keeping in place an ICs
program. More specifically, Alternative 4 consists of the following technologies:
• Cap placement
• Resuspension management
• Residual management
• Cap material conveyance/transport
• Institutional controls
• Monitored natural recovery
Alternative 4 builds on the work done under Options for In Situ Capping ofPalos Verdes Shelf
Contaminated Sediments (Palermo et al., 1999), included as Appendix E, and the Engineering
Evaluation/Cost Analysis for the Palos Verdes S/ze//(USEPA, 2000) that identified two cap areas
that would cover most of the Shelf along the 60-m isobath. More recent data indicate COC
concentrations have dropped across the Shelf, allowing a reconsideration of the size and
location of potential caps. Tables 5-1 and 5-2 provide fill requirements for various capping
scenarios. Grid cells were developed for the entire PV Shelf, although the slope (B cells) can
not be capped. The following subsections discuss the various technologies necessary to
implement this alternative.
5.2.4.1 Capping Objectives and Design Basis
The objectives of placing a cap on the PV Shelf Study Area are:
• Reduce contaminant flux from the area of highest contaminant concentrations
• Replace effluent-affected sediment with clean material, creating a cleaner environment
for benthic recolonization
• Consolidating and stabilizing the bottom boundary layer (mudline)
The EPA Assessment and Remediation of Contaminated Sediments (ARCS) Program Guidance for
In-Situ Subaqueous Capping of Contaminated Sediments (USEPA, 1998) details design criteria
and considerations for an in situ cap. Pertinent processes considered in the development of
this alternative include effective short- and long-term chemical isolation of contaminants,
disturbance and mixing of sediment by benthic organisms, consolidation of compressible
material, and erosion. The Options for In Situ Capping of Palos Verdes Shelf Contaminated
Sediments (Palermo et al., 1999) contains a cap placement and operations plan for a 45-cm
cap that would be updated as part of the remedial design/remedial action if this alternative
were selected.
5.2.4.2 Capping Areas
Areas considered for capping would be where the COC surface concentrations are highest
and/or where erosion is most likely to occur. However, some areas are unsuitable for active
remediation. For example, risk of liquefaction from seismic activity was evaluated using
USAGE'S WESHAKE model (Schnable et al., 1972, Sykora et al., 1994). The results indicated
that contaminated sediment on slopes of 5 degrees or greater are susceptible to flow failure
if subjected to moderate earthquakes (Palermo et al. 1999). Based on this evaluation, areas
on the site with bottom slopes less than 5 degrees are suitable for capping from the
standpoint of seismic considerations, but areas with bottom slopes exceeding 5 degrees
5-16 MAY09PVSCHAPT5.DOC
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
should not be considered for capping. The PV Shelf is relatively flat until the shelf break. In
general, areas deeper than the 70-m contour are not suitable for capping.
Alternative 4 caps with clean sand the areas on the shelf with the highest surface
concentrations of COCs that are also relatively level. Surface concentrations of COCs are
highest around the outfalls and slope; however, as discussed above, the slope is not suitable
for remediation. The cells with highest surface concentrations on the more level shelf area
are Grid Cells 6C, 7C, and 8C (Figure 5-4). This represents an area of approximately 2.74
km2, or 680 acres.
Grid Cells 6C, 7C, and 8C.
Grid Cells 6C, 7C, and 8C include the area of highest contaminant concentrations, i.e., the
outfall area, as well as the cells to the northwest of the outfall. Cell 8C is on the southeast
edge of the deposit and appears to be erosive. North of the outfall pipe, Cells 7C and 6C
have been net depositional; however, a recent model of sediment transport suggest that
without a source of sediment (e.g., Portuguese Bend or the outfalls), the area may loose 0.3
to 0.1 mm of sediment annually (Ferre and Sherwood, 2008). Earlier models (Sherwood,
1996) suggested the area would experience a temporary increase in surficial concentrations
of COCs before reaching equilibrium.
5.2.4.3 Cap Thickness
Considerations that went into cap design include physical and chemical properties of the
contaminated and capping sediments, hydrodynamic conditions such as currents and
waves, potential for bioturbation of the cap by benthic organisms, potential for
consolidation of the cap and underlying sediment, and operational considerations. Total
cap thickness is normally composed of components for bioturbation, consolidation, erosion,
operational considerations and chemical isolation.
As discussed in the previous section, seismic considerations limit the areas that can be
considered for capping. Seismic considerations also limit the thickness of a cap. The weight
of the cap reduces the safety factor against flow failure during an earthquake. A cap with
thickness up to 60 cm (2 feet) would not render the EA sediment susceptible to flow failure
on those areas of the shelf with slopes of less than 5 degrees. A cap on slopes of up to 5
degrees would be susceptible to pore pressure development under cyclic loading, and
would likely liquefy if subjected to a moderate earthquake, but would restabilize. With
these limitations in mind, to effectively isolate and immobilize the COCs, Options for In Situ
Capping ofPalos Verdes Shelf Contaminated Sediments, (Palermo, et al. 1999) proposed a cap of
45cm.
Recent assessments conducted for and discussed in the Palos Verdes ShelfSuper fund Site
Remedial Investigation Report (CH2M Hill, 2007) confirm that 45 cm would be adequate for an
isolation cap. Recommended cap thickness to physically isolate the EA material from
benthic organisms was estimated to be 45 cm, 30 cm to account for the bioturbation zone
and the enhanced biodiffusion zone, plus an operational tolerance layer of 15 cm. Recent
studies in 2004 (SAIC, 2005) confirmed that bioturbation occurred primarily in a thin (10 to
15 cm) surface layer. Although deep bioturbators like ghost shrimp were found on PV
Shelf, their numbers were low and they generally resided in shallower waters than the EA
deposit. A 45-cm cap is still considered adequate to isolate the contaminated sediment from
benthic organisms.
/MAY09PVS CHART 5.DOC 5-17
-------
TABLE 5-1
Fill Volumes Required for Sediment Cap of PV Shelf Study Area Grid Areas
Cell
OB
OC
OD
1B
1C
1D
2B
2C
2D
3B
3C
3D
4B
4C
4D
SB
5C
5D
6B
6C
6D
7B
7C
7D
SB
8C
8D
9B
9C
9D
10B
10C
10D
Totals
Cell Area
(sq km)
11.06
7.77
6.75
6.88
4.74
3.30
1.30
1.30
1.42
1.25
1.19
0.95
1.60
1.93
1.85
1.01
1.36
1.69
0.38
0.67
1.24
0.33
0.74
1.04
1.00
1.33
1.99
1.45
2.48
2.92
1.26
4.43
3.56
82
(sq mi)
4.3
3.0
2.6
2.7
1.8
1.3
0.5
0.5
0.5
0.5
0.5
0.4
0.6
0.7
0.7
0.4
0.5
0.7
0.1
0.3
0.5
0.1
0.3
0.4
0.4
0.5
0.8
0.6
1.0
1.1
0.5
1.7
1.4
32
(acres)
2731
1918
1668
1698
1170
814
322
322
350
308
295
236
394
476
456
249
335
418
94
166
307
82
182
258
247
329
492
357
611
720
310
1094
880
20290
Volume of Fill 1 (m3)
45-cm cap
4,976,000
3,495,000
3,040,000
3,094,000
2,131,000
1 ,484,000
586,000
587,000
638,000
561 ,000
538,000
430,000
718,000
867,000
830,000
454,000
610,000
762,000
171,000
302,000
559,000
150,000
332,000
469,000
450,000
600,000
897,000
651 ,000
1,114,000
1,312,000
565,000
1 ,993,000
1 ,603,000
36,969,000
Cap Volume with
Assumed 20% Loss
Factor (m3)
45-cm cap
5,971 ,200
4,194,000
3,648,000
3,712,800
2,557,200
1 ,780,800
703,200
704,400
765,600
673,200
645,600
516,000
861 ,600
1 ,040,400
996,000
544,800
732,000
914,400
205,200
362,400
670,800
180,000
398,400
562,800
540,000
720,000
1 ,076,400
781 ,200
1 ,336,800
1 ,574,400
678,000
2,391 ,600
1 ,923,600
44,362,800
1 Estimated volume of fill is equal to the volume of sediment required to fill a 15 cm or 45 cm prism
covering the area of each cell. Bulking factor and loss ratio were assumed negligible.
-------
TABLE 5-2
Chemical and Physical Data for Potential Cap Scenarios
Cap Area Scenarios
Cap Cells
8C
7B, 7C, 8B, 8C
5B, 5C, 6B, 6C, 7B, 7C,
8B, 8C
USAGE Cap Area A
USAGE Cap Area AB
PV Shelf Study Area
Area1
sq km
1.3
3.4
6.8
4.9
7.6
82.2
Acres
329
841
1685
1210
1877
20290
% of total
1 .6%
4.1%
8.3%
6.0%
9.3%
100.0%
Mass of DDTs in
Surface
Sediment2'3
(kg)
2249
2589
2811
2229
2366
5109
(Ib)
4948
5697
6185
4903
5206
11240
% Mass Study
Area DDTs in
Surface
Sediments
44%
51%
55%
44%
46%
100%
Mass of PCBs in
Surface
Sediment2'3
(kg)
85
141
235
145
199
666
(Ib)
188
310
518
320
439
1464
% Mass Study
Area Total
tPCBs in
Surface
Sediments
13%
21%
35%
22%
30%
100%
Cap Volume
(45 -cm)
(m3)
600,000
1,532,000
3,069,000
2,205,000
3,420,000
36,969,000
(CY)
790,000
2,010,000
4,020,000
2,890,000
4,480,000
48,360,000
Cap Volume
(45-cm)
(Assumed 20% Loss)
(m3)
720,000
1 ,840,000
3,690,000
2,650,000
4,110,000
44,370,000
(CY)
950,000
2,410,000
4,830,000
3,470,000
5,380,000
58,040,000
1 The area for each polygon was determined by using SURFER based on Figure 1-8.
2 Surface sediments defined as the upper 0.8 inches (2 cm) of sediment. Data is from LACSD surface sampling (Van Veen sampler) conducted in July 2002 and 2004.
3 Dry soil density was used to estimate the mass; density varies with station locations and depth based on data from Sherwood et al., 2006 (see table below).
Station
1C
2C
3C
4C
5C
6C
7C
8C
9C
Surface
0-1 5 cm
(g/cm3)
1.00
0.95
1.00
0.90
0.80
0.75
1.10
0.60
1.10
Deeper
> 15 cm
(g/cm3)
1.10
1.10
1.00
0.90
0.75
0.75
0.80
0.50
1.25
Estimated volume of fill is equal to the volume of sediment required to fill a 45-cm prism covering the area of each cell.
The bulking factor and loss ratio were assumed negligible. The fill volume required to cap individual grid cells is provided in Table 5-1.
-------
5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
Another consideration in selecting cap thickness is consolidation of capping material and
effectiveness of cap in containing sediment porewater (i.e., chemical isolation). A
consolidation analysis of the underlying EA sediment was necessary to analyze potential
contaminant flux. Computation of the volume of pore water expelled is needed to estimate
the thickness of cap affected by advection. Compressibility of the EA sediments varies from
low to moderate. USAGE used their RECOVERY model to estimate diffusive flux and
resultant changes over time in sediment and porewater contaminant concentrations and the
flux of contaminants into the water column. Results for a 45-cm cap showed essentially
complete isolation for over 100 years (Palermo et al., 1999).
5.2.4.4 Cap Material
The specification of cap material requires knowledge of the shear stresses created at the
bottom boundary layer to assure cap stability. Modeling of potential cap material was
performed to determine critical shear stress of the designed cap. A revised and refined
version USACE's Long Term FATE (LTFATE) model (Scheffner 1996, Scheffner et al. 1995)
was used to screen areas where erosion would be a factor in cap design and/or where
capping would not be recommended due to erosion potential. The LTFATE model was
used to simulate erosion over defined model grids of 1 x 4 km and 2x2 km located in water
depths of 30 m to 100 m. Three representative capping materials were modeled: 0.3 mm
sand, 0.1 mm sand, and cohesive silt and clay. Wave conditions for the model runs were
based on hypothetical events with wave heights of 5.5 and 7.0 m and on historical data of
the largest storms from a 20-year period. Results from the LTFATE modeling indicated that
significant erosion of sand-sized materials would occur only in water depths shallower than
40 m. Caps of silt and clay material would have greater erosion potential than coarser
material. Cap designs consisting primarily of sandy material in water depths exceeding 40
m would be stable with minimum susceptibility to erosion.
Cap Material Sources
The amount of cap material required to provide a 45-cm cap for Grid Cells 6C, 7C, and 8C
plus a 10 percent loss allowance is 1,358,000 m3 (1,776,000 yd3).
Because beaches in Southern California are eroding, the sand generated from dredging and
construction projects is a valuable resource that typically is used beneficially for beach
nourishment, or in-water and upland construction. Maintenance or new construction
dredging material is often contaminated and not suitable for open water disposal. The
availability of cap material will have to be critically evaluated and the project may need to
be timed with dredging or major construction projects that will generate enough good
quality sand. Cost and timing of procuring cap material will be a critical design
consideration.
Potential sand cap sources were identified and evaluated for this FS through review of
existing literature regarding sediment in Southern California and discussion with members
of the dredging community, the U.S. Army Corps of Engineers, Los Angeles District, and
the Ports of Los Angeles and Long Beach. Two major efforts are underway to evaluate
sediment and the quality of those sediments in Southern California, as discussed below. An
additional, unpublished effort by the California Geological Survey that identified offshore
sand resources for borrow pits was completed in 2005.
5-20 MAY09PVS CHART 5.DOC
-------
Palos Verdes Peninsula
-300/
Grid Cell 7C
Pacific Ocean
--600.
Abbreviations
LACSD Sanitation Districts of Los Angeles County
M Meters
Legend
•5B LACSD sediment sample station
u>~~ Isobath contour (meters)
Study Area
Boundary
(-200-M Isobath)
>9D
9B
A
0 0.5
Approximate Scale (Miles)
Feasibility Study Report
Palos Verdes Shelf
Los Angeles County, California
FIGURE 5-4
Layout of
Grid Cells 6C, 7C, and 8C
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
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5-22 ES042007001SCO/DEC08 CHAPT 5.DOC/070920001
-------
5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
The California Coastal Sediment Management Workgroup (CSMW) was formed as a
collaborative effort between federal, state, and local agencies and nongovernmental
organizations to evaluate California's coastal sediment management needs on a regional,
system-wide basis (CMSW, 2007). The CSMW, as part of their Sediment Master Plan (SMP)
attempts to address requests of coastal regulators for sediment budget information to assist
them in their sediment management decision-making. A complete evaluation of sediment
sources and when they will be available is under development by CSMW.
The Los Angeles Region Contaminated Sediment Long-Term Management Strategy (CSTF)
is a collaborative effort by staff from federal, state, and local agencies, ports, research
organizations, environmental advocacy groups, and private consulting firms. The main
goal of the CSTF is to have regional coordination of sediment management efforts with a
process for evaluating contaminated sediment dredging projects to minimize potential
adverse environmental impacts associated with the dredging and disposal of contaminated
sediments. An additional proposed long-term goal is to beneficially reuse sediments.
The CSTF provided projected volumes of sediment from known port capital improvement
projects. The CSTF calculated potentially available dredged sediment quantities from
anticipated POLA, POLE, and Alamitos Bay capital improvement projects and used
historical records to project maintenance volumes from other sites. Data from the 2005
CSTF have not been updated unless noted. These and other projections of potential cap
sediment quantities from regional sources are presented in Table 5-3.
Another potential sediment resource for capping material is from offshore borrow pits.
The California Geological Survey (CGS) for the U.S. Minerals Management Service (MMS)
and the California Department of Boating and Waterways (DBW) has prepared an
unpublished assessment of offshore sand resources for potential use as beach nourishment
(Higgins et al., 2005.). The assessment mapped the sediment types and volumes offshore of
the Southern California Bight. This assessment focused on MMS jurisdiction the three
nautical-mile limit that separates the jurisdiction of the federal government (MMS) and the
State of California. Maximum water depths for economical operation of hydraulic dredges
(cutterhead-suction and trailing-suction hopper, which are standard for offshore sand
extraction) are typically limited to 30 m (about 100 feet).
Based on the technological, economic, and legal conditions, there are currently few areas
under MMS jurisdiction along the coastal shelf in Southern California that would be
accessible for potential extraction of sand. However, sand resources in-shore of the 3-
nautical-mile limit, which are in shallower water depths and technically easier to dredge,
are under the jurisdiction of the California Division of State Lands and the California
Coastal Commission. The CGS report provides maps of mineral type (e.g., sand, mud
gravel, rock) and tables of potential supplies. The most desirable deposits are
unconsolidated, have large volumes, are similar in physical character to the material of the
receiving site, and are free of contaminants and debris.
If this alternative were selected, maintenance dredging projects and construction projects
that would coincide with the cap construction would be evaluated as a source during the
design phase. A portion of the volume required for a cap may be available from a dredging
or construction project, but it is probable that no single dredging or construction project
would generate sufficient volumes of acceptable cap material to construct the entire cap.
Therefore, it is likely that a borrow area would be required to provide a portion or the entire
volume of material needed to construct the cap. While locating a borrow area for source
/MAY09PVS CHART 5.DOC 5-23
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TABLE 5-3
Potential Cap Source Material and Volumes
_ . ...,,. Feasibility Issues
Potential Unhimp
Potential Cap Source Potential Suppliers
Port of LB Capital
Dredging Projects Improvement Dredging1
Port of LA Capital
Improvement Dredging1
Channel Islands Harbor
Maintenance Dredging2
Marina del Rey entrance
channels1
Santa Ana River
Maintenance Dredging3
(yd3) Timeframe Positive
Port of LB has capital
2,121,000 Over 5 years Improvement needs
Port of LA has capital
1,570,000 Over 6 years Improvement needs
Clean Sand, typically used
1,000,000 Every 2 years for beach nourishment
Maintenance dredging has
43,000 to 87, OOO4 Every 3 to 5 years historically been necessary
1,500,000 About Every 10 years Distance is manageable
Negative
Also needed for Port
Construction
Also needed for Port
Construction
Need approval for alternate
disposal location
Need to evaluate impacts to
no beach nourishment
alternative
Typically 1/4 to 1/3 of material
is unsuitable for open water
disposal
Typically brokered for inland
industrial uses
Upland Construction
Projects
CalTrans
No Data Available
Clean soil
High Transportation Costs
Need handling area to
transfer from trucks to barge
Need to evaluate
compatibility; could be
different than in-water
dredged sediments
Borrow Pit
In-water Mining
Near-shore sand sources in
the Los Angeles/Ventura
Region5
>20,000,000
After an estimated 3
years of permitting
Clean sand supplies in near-
shore off of Long Beach,
Los Angeles, and Ventura.
No approved sand borrow pits
-------
TABLE 5-3
Potential Cap Source Material and Volumes
_ . ...,,. Feasibility Issues
Potential Volume
Potential Cap Source Potential Suppliers (yd3) Timeframe Positive Negative
Need to conduct EIS to
evaluate impacts to marine
Sand similar to existing environment, permit process
marine habitat could need 3 years to permit.
Sources need to be shallower
than 100 feet based on
hydraulic dredge technical
requirements
Upland Mining No Data Available Need to Purchase Material
High costs of mining, trucking,
handling, and disposal
1 Estimated dredge volumes at the time of CSTF (2005) publication
2 Personal communication with Manson Construction and Corps LA District
3 Moffatt and Nichol, 2006. Final Sand and Opportunistic Use Program Plan. Prepared for SANDAG
4 Assumes 60,000 to 130,000 cy/year and 1/3 is not suitable for open water disposal
5 Table A-4 in Higgins, C.T., Downey, C.I., and Clinkenbeard, J.P., 2005, Assessment of offshore sand resources for potential use in restoration of beaches in California:
California Geological Survey, unpublished report prepared for U.S. Minerals Management Service and the California Department of Boating and Waterways, 153 p.
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
material, location, type of material, volume of material, and potential regulatory
requirements will be considered. Clean areas of the shelf would be assessed as potential
borrow areas. For purposes of costing this alternative, it is assumed that a sufficient amount
of material will be available from a borrow site.
5.2.4.5 Cap Placement Techniques
This alternative assumes that at least two cap placement techniques would be required: an
initial cover would be placed using a submerged release, i.e., a submerged drag arm or a
tremie tube with diffuser. The appropriate equipment will be determined during the
remedial design phase. Once this initial cover is placed, the cap construction would
continue using the spreading method with a split-hull material barge or hopper dredge.
The pilot capping project determined that the spreading method resulted in less disturbance
to the EA sediment compared to the point-placement method (Fredette et al., 2002). The
spreading method is a relatively rapid placement technique with a relatively minor
modification to conventional methods. After the initial layer is placed, the spreading
method would be used in locations away from the LACSD outfalls. A buffer zone around
the outfalls would require use of precise placement methods to avoid any negative impacts
to the outfalls from cap construction.
Based on production rates used in Options for In Situ Capping (Palermo et al. 1999) cap
construction is anticipated to occur over two seasons. Average hopper dredge capacity is
1,800 cubic yards. Therefore, a 45-cm cap would require approximately 1,000 hopper loads.
The pilot capping project determined that the sequence of cap material placement had
significant effects on disturbance of the EA sediment (SAIC, 2002). Placement sequence
would be from up-current to down-current and upslope to downslope, starting at the edge
of the deposit.
5.2.4.6 Cap Monitoring
Cap monitoring would consist of two components: (1) construction monitoring, and
(2) long-term cap performance monitoring. Monitoring activities for the construction phase
are intended to (1) document the preplacement or baseline physical and biological
conditions within and adjacent to the capping prisms, (2) guide the placement of dredged
material within representative cells of the capping prism, and (3) document changes in
water quality and any apparent displacement and transport of contaminated PV Shelf
sediments resulting from the construction of a cap. The focus of the construction phase
monitoring is to guide the construction work and evaluate whether the cap design
specifications were achieved. Part of this monitoring would involve periodic testing of
material being used for the cap to ensure that it meets design criteria, particularly for grain
size characteristics.
The focus of the long-term performance monitoring is to determine whether physical and
chemical isolation objectives are achieved over longer time periods and to provide a basis
for determining if further action is needed. Longterm cap performance monitoring would be
designed to accomplish the following:
• Determine whether the areal extent and thickness of the cap as constructed achieves the
design specifications.
• Determine the effectiveness of the cap in isolating contaminated sediments.
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
• Determine the extent of biological recolonization and bioturbation.
Construction Monitoring. Cap construction-phase monitoring would require baseline,
interim, and post-cap-placement measurements. Construction monitoring would provide
real-time feedback on capping progress to allow modification of techniques to improve
effectiveness as well as assure environmental impacts are minimized. Construction
monitoring would use current and turbidity measurements to track sediment plumes.
During the pilot capping project, acoustic doppler current profilers (ADCPs), optical
backscatter sensors (OBS), drogues, sediment cores and Niskin water sample bottles were
among the equipment used to measure and track current speed and turbidity. Operational
procedures and guidelines developed for the pilot capping project (SAIC, 2000) would be
modified as needed for cap construction. Interim and post-cap-placement monitoring
would be used to determine the thickness and physical properties of the cap layer. Sub-
bottom surveys would provide information on the thickness of the cap layer over a
relatively large area. The survey would provide information on layering within sediment
profiles due to sorting or segregation of distinct sediment size ranges during settling of the
cap material.
Sediment cores, collected using box cores, are intended to provide information on cap
thickness and layering, as well as the vertical distribution within the core of sediment
contaminants. For the purposes of this FS, it is assumed that sediment cores would be
collected at 50 locations before, during, and after cap placement. Sediment cores would be
analyzed for TOC, bulk density, grain size and DDE. Water column samples would be
collected from 12 stations (2 depths) during construction and analyzed for DDTs and PCBs.
Long-Term Performance Monitoring. Long-term cap performance monitoring would consist
of evaluating biological recolonization and physical and chemical isolation of the
underlying contaminated sediment. The rates and extent of recolonization would be
evaluated over a defined grid of 50 sampling locations after capping and before the Five
Year Review. Physical isolation of the contaminated sediment layer would be evaluated
over the entire cap area after cap construction and for the Five-Year Review. Chemical
isolation would be evaluated using passive samplers deployed over the cap to measure
contaminant flux from the cap as well as from sediment cores collected at 12 locations at the
same sampling frequency as the physical isolation monitoring. For these stations, the
contaminant mass and vertical distribution will be evaluated in each core by analyzing 4-cm
segments for DDTs and PCBs from the surface to a depth of 100 cm (25 samples/core).
5.2.4.7 Resuspension Management
Resuspension management in Alternative 4 would include using BMPs during in-water
work; engineering and in-water construction methods designed to minimize resuspension;
and engineering design to minimize events such as slope failures, debris flows, or
avalanches. Some examples of specific BMPs that would be implemented at the PV Shelf
include the use of low-impact placement techniques, such as dragarm or tremie tube, that
minimize the energy with which the cap material impacts the bottom sediments, or staging
and tracking of placement locations to prevent mounding that might result in slope failures
that could cause debris flows or avalanches. Engineering design to minimize resuspension
of sediment during capping would include placing an initial layer of cap material over the
sediment of the PV Shelf using low-impact techniques mentioned above, then build the cap
using more efficient techniques such as spreading.
/MAY09PVS CHART 5.DOC 5-27
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
5.2.4.8 Residual Management
Alternative 4 will use monitoring to manage residual sediment contamination at the PV Shelf
Study Area. Residual contaminated sediment will remain exposed to the environment after
cap construction because of limitations to the precision of cap construction (thickness and
lateral coverage of cap material), limitations in placement techniques that cause mixing of the
cap material and the effluent-affected sediments, and limitations of the constituents that are
present in available cap material. This would include material at the margins of the cap
where the cap material thickness feathers out or residual contamination that settles on the
cap following resuspension during placement of cap material at an adjacent location. Note
that the engineering design will consider factors such as prevailing current directions to
mitigate these conditions. Ideally, there would be no surface contamination remaining after
cap construction; however, that is dependent on a number of factors including the cap
material placement technique, thickness of the cap, the number of lifts used to place the cap,
sediment physical characteristics of both cap and indigenous sediments, vertical distribution
of contaminants in native sediments, and site hydrodynamics such as current and waves.
5.2.4.9 Material Conveyance/Transport
Under Alternative 4, a source for cap material has not been selected. However, some
potential sources are identified in Table 5-3. The most likely sources are in-water. A hopper
dredge would be used for loading and transport of material from the in-water source to the
project site. The hopper dredge can load the material into its hoppers without the use of
additional equipment. If the cap material comes from a shore, typically a barge or scow
would be used for transport. Material would be loaded onto a barge or scow using a
mechanical dredge for near-shore fill sources. Material from upland sources would be
transported to the barge using trucks or possibly rail cars and either dumped directly on the
barge deck or placed in a stockpile to be transferred to the barge using a crane or excavator.
5.2.4.10 Institutional Controls and Monitored Natural Recovery
The institutional controls and monitored natural recovery programs for Alternative 4 are
described under Alternative 2.
5.2.5 Alternative 5-Removal with Institutional Controls and Monitored Natural
Recovery
Alternative 5, Removal with Institutional Controls and Monitored Natural Recovery,
consists of dredging that portion of the EA sediment deposit that contains sediment with the
highest concentrations of contaminants at surface and depth, i.e., Grid Cell 8C. The
alternative includes treatment and disposal of dredged sediment at an upland off-site
disposal facility. Water collected from the dewatering of dredged sediment would require
treatment before disposal. ICs and MNR programs would also be implemented. Appendix
F provides details of this alternative.
Dredging technologies were reviewed to determine the most appropriate method to remove
sediment from grid Cell 8C at a depth of 50 to 70 m. The main limiting factor is the depth of
the deposit. Other dredging issues include resuspension of sediments and dredging
accuracy. Performance standards for the site include being able to reach depths up to 70 m,
achieve acceptable production rates, dredge in thin lifts while minimizing overdredging,
5-28 MAY09PVS CHART 5.DOC
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
and minimize resuspension of sediments. A trailing suction hopper dredge was selected as
the technology most likely to meet these performance standards.
5.2.5.1 Dredging Area
Grid Cell 8C at the PV Shelf covers approximately 320 acres at a depth from 50 m to 70 m, or
to the shelf break. The estimated depth of sediment to be dredged is approximately 75 cm,
not including overdredging. Grid Cell 8C contains total mass of DDTs in surface sediment
of approximately 2,250 kg, accounting for approximately 44 percent of the total mass of
DDTs in PV Shelf surface sediment. The total mass of PCBs present in surface sediment in
Cell 8C is 85 kg, accounting for 13 percent of total mass of PCBs in PV Shelf surface
sediment. Grid Cell 8C includes the JWPCP outfalls. The estimated volume of dredged
material is approximately 1,345,000 yd3, or 1,613,000 yd3, including overdredging. An
estimated 1,487,950,000 gallons of water would be generated during sludge and sediment
dewatering (Appendix F: Tech Memo: Development and Analysis of Removal Alternative,
ITSI 2008).
5.2.5.2 Dredging Design
Sediment removal would be performed with hydraulic dredging equipment, i.e., a trailing
suction hopper dredge and two scow barges. The dredge is connected with drag arms and
drag heads that dredge the bottom of the shelf. The sediment is pumped in slurry form
through pipes to the scow barge, which is taken to shore upon reaching capacity, where the
material is pumped into a decanting basin. Two scow barges would be utilized to allow for
continuous dredging operation. One barge would be receiving sediment while the other is
unloading the sediment on shore. The trailing suction hopper dredge would be positioned
with a tug and dragline. The hopper dredge is more difficult to control the deeper the
dredge depth, especially under open ocean currents and with long drag arms. To increase
the confidence that the targeted sediment is removed, overlap between dredge passes is
recommended.
Production rate for the trailing suction hopper dredge is dependent on many factors,
including the size of the dredge pump, the physical composition of the sediments to be
dredged, and the physical composition of the materials below the sediment to be dredged.
Rough estimates of a U.S. dredging company is 1,000 cubic yards per day, with two 2,000
cubic yard scows working in rotation. Dredging even the limited area defined by Grid Cell
8C would be a multi-year operation, estimated to take 12 years.
The trailing suction hopper dredge would not operate near the outfall pipes or rock
outcrops to prevent equipment damage. Additionally, the dredge cannot be controlled
accurately enough to dredge steep slopes and could not be used along the PV Shelf slope
because of its steepness and depth.
5.2.5.3 Residual and Resuspension Management
Sediment resuspension during operation of hydraulic dredges occurs when sediment
dislodged by the dredgehead escapes the suction pipe. Two important factors in
resuspension for hydraulic dredges are the depth of the cut and the speed of advance of the
dredgehead. Sediment resuspension by hydraulic dredges is typically more concentrated in
the lower portion of the water column, where the dredgehead encounters the sediment
(USAGE, 2008a). Suction dredges are considered favorable for sediment resuspension
/MAY09PVS CHART 5.DOC 5-29
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
control because they have no mechanical action at the dredgehead to dislodge sediment;
therefore, resuspension potential is due solely to the advance of the dredge head through
the sediment (USAGE, 2008b).
Contaminated sediment could remain exposed to the environment after dredging operations
because of its imprecision. Extra passes is the accepted approach to limit residuals,
however, this would increase the volume of material needing disposal. Residual
management is addressed by including most of the buried deposit; therefore, the residual
sediment would have low COC concentrations. However, a temporary increase in COC
availability is typically associated with dredging operations (USAGE, 2008a). BMPs to
minimize residuals and resuspension would be enforced. Production would be limited to
seasons when the ocean is calm, e.g., late spring and summer. Typical mechanisms to
manage resuspension and residuals, like containment barriers or silt screens, could not be
used during dredging of the PV Shelf because the depth of the site makes them infeasible.
5.2.5.4 Management of Dredged Sediment
Hydraulic dredging operations require the sediment to be mixed with water to allow the
material to be pumped through a dredge pipe. The sediment coming out of the dredge pipe
for plain suction dredging will have a solids content of approximately 10 percent. The
volume of the sediment slurry that would be generated during dredging operations is
estimated to be 10,640,000 cubic yards. The Cell 8C sediment is characterized by clay and
silts, significantly elevated organic carbon content, and low bulk densities. This sediment
generally does not dewater quickly with gravity dewatering and would require a decanting
basin. The size of the basin depends on several factors, including dredge production, solids
content of dredge sediment, available area, water treatment layout, etc. The decanting
basin would be divided into multiple cells where dewatered sediment can easily be
transferred to another area within the basin to be prepared for offsite transport by bulking
or solidification. Multiple operations would be underway within the decanting basins at
each cell. It is estimated that the volume of sediment after decanting would be
approximately 3,610,000 yd3.
After dewatering, the dredged material would undergo solidification through the addition
of a reagent. Because the sediment would require further treatment before it could be
disposed of, typical binding agents, such as cement or lime, may not be suitable. The reagent
would have to be evaluated to provide absorption of moisture without interfering with
thermal desorption.
Treatment of water generated as a result of dredging and dewatering is required. The
estimated volume of water is 1,487,950,000 gallons. In order for the water to be discharged
to the ocean in accordance with Section 403 of the Clean Water Act, Title 40, CFR Part 125,
Subpart M, it would have to be treated to meet State of California water quality standards.
Filtration would be used to remove suspended solids before water treatment with
granulated activated carbon (GAC).
5.2.5.5 Dredged Material Disposal
Removal of the contaminated sediment would require the additional process option of
disposal. Once the contaminated sediment was removed, it would be necessary to manage
it by (1) placing it in a confined disposal facility (CDF) or contained aquatic disposal (CAD),
(2) disposing of it in the deep ocean, or (3) disposing of it in a landfill. As discussed in
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
Section 4, all of these options are problematic. The most likely option of these four,
however, is disposal in an EPA-approved landfill. Because the levels of PCBs in the EA
sediment are less than 50 mg/kg, the dredged material would not be considered toxic
material under TSCA; however, since the sediment would be considered PCB-remediation
waste, per 40 CFR 761.61(c) a site-specific disposal plan would need to be prepared for
approval by the EPA Regional Administrator. In addition, the dredged material would be
considered RCRA-listed hazardous waste. The material would require pretreatment prior
to disposal to reduce the water content and concentrations of DDT and DDE to acceptable
concentrations, i.e., less than 0.087 mg/kg.
The technology selected for removal of DDTs and PCBs contained in the dewatered
sediment to a level acceptable for land disposal is thermal desorption. Thermal desorption
can be high temperature (HTTD) or low temperature (LTTD). Low temperature is typically
applied to contaminants with relative low boiling points (i.e., below 600° F) while high
temperature is typically applied to contaminants having boiling points above 600° F (Naval
Facilities, 1998). DDT would be suitable for LTTD, while PCBs would require HTTD.
5.2.5.6 Institutional Controls and Monitored Natural Recovery
The institutional controls and monitored natural recovery programs for Alternative 5 are
described under Alternative 2.
5.3 Screening of Alternatives
The purpose of this section is to screen the five assembled alternatives for implementability,
effectiveness, and cost, and to determine if any should be omitted from detailed analysis in
Section 6.0. The five alternatives assembled and developed in Section 5.2 are:
• Alternative 1 — No Action
• Alternative 2 — Institutional Controls with Monitored Natural Recovery
• Alternative 3 — Containment (Small Cap) with Institutional Controls and Monitored
Natural Recovery
• Alternative 4 - Containment (Large Cap) with Institutional Controls and Monitored
Natural Recovery
• Alternative 5 - Removal with Institutional Controls and Monitored Natural Recovery
5.3.1 Alternative 1— No Action
Effectiveness. All current risks would remain unabated under the no action alternative.
Untreated contamination in sediment would continue to pose a risk to human health and
the environment for many years. Although degradation and other fate-and-transport
processes would reduce the concentrations to below levels of concern for much of the shelf,
the area around the outfalls would continue to exceed remediation objectives for much
longer. Changes in overall risk from the site would be difficult to assess since no
monitoring would be performed under this alternative. Based on current understanding of
fate and transport processes, under the no action alternative, RAOs would be met in 30 to
over 100 years.
Implementability. The no action alternative would be easy to implement because no action is
being taken.
/MAY09PVS CHART 5.DOC 5-31
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
Cost. No action, by definition, would have no associated costs.
5.3.2 Alternative 2—Institutional Controls with Monitored Natural Recovery
Effectiveness. The institutional controls (ICs) program has moderate to high effectiveness.
Institutional controls can be effective in reducing the number of contaminated fish being
eaten by consumers; however, it does not reduce contaminant concentrations in fish.
Institutional controls do not reduce the risk to ecological receptors. Monitored natural
recovery (MNR) has low effectiveness in the short-term and moderate effectiveness in the
long-term. The effectiveness of MNR at the site will be determined through sampling and
monitoring. Modeling predicts that contaminant concentrations may reach remedial
objectives within 30 to 100 years; however, monitoring would be required to confirm
recovery. Although median sediment and water concentrations would drop to levels
associated with remediation goals for safe fish consumption, the outfall area would not
reach remediation goals for over 100 years. Whether this would prevent fish from reaching
remediation goals is not known. Although natural recovery has improved conditions on
portions of the shelf, other areas appear to be becoming worse, i.e., the outfall area.
Implementability. Institutional controls are easy to moderate to implement. The materials
and services to implement outreach and education, enforcement, and monitoring are readily
available. MNR is also easy to implement. Sampling techniques to monitor recovery are
proven and readily available.
Cost. The cost of the ICs program and MNR are less than the other alternatives. However,
they are elaborate programs that would cost millions over the next ten years.
5.3.3 Alternative 3—Small Cap with Monitored Natural Recovery and Institutional
Controls
Effectiveness. The institutional controls (ICs) program has moderate to high effectiveness.
Institutional controls can be effective in reducing the number of contaminated fish being
eaten by consumers; however, it does not reduce contaminant concentrations in fish.
Institutional controls do not reduce the risk to ecological receptors. Alternative 3 is relatively
more effective than Alternative 2 because it accelerates natural recovery. The area of the
shelf that contains the highest contaminant concentrations and is most susceptible to erosion
would be covered with clean sediment to reduce contaminant flux and movement of
contaminated sediment. Remediation goals would be achieved fourteen years sooner than
under Alternative 2. In the interim, risk to ecological receptors from contaminated sediment
and water would continue.
Implementability. The implementability of Alternative 3 is moderate. The ICs program has
been in operation for many years. The materials and services to implement outreach and
education, enforcement, and monitoring are readily available. Enhancing MNR through
placement of a small cap would be more difficult than merely tracking natural recovery.
Although placing a sediment layer at 50- to 70-m depth adjacent to discharge outfalls has
not been done, the equipment and techniques that would be utilized have been
implemented in many other sites.
Cost. The cost of Alternative 3 is seven times higher than Alternative 2.
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
5.3.4 Alternative 4—Containment with Monitored Natural Recovery and
Institutional Controls
Effectiveness. Alternative 4 has the potential to be more effective than the other
alternatives. If properly designed and placed, a sand cap can be an effective technology in
reducing the overall risk from the site. The 2000 pilot capping project evaluated
three placement methods for a sand cap over three 45-acre (300 m x 600 m) cells and
concluded that capping is a technically feasible option for the site (Fredette et al., 2002).
However, monitoring during and after cap placement found mixed results in effectiveness
of reducing surficial contaminant concentrations (SAIQ 2002). Monitoring during cap
placement observed increases in turbidity as cap material hit the shelf floor and created a
surge wave. For the most successful cap, Cell LU at 40 m, the initial drop of cap material
created a vertical plume of suspended sediment 13 m thick and an annulus with the radial
dimension of approximately 220 m (SAIQ 2002). However, both plume and annulus
quickly decreased with distance and time. Point dump of cap material on the deeper cell,
Cell SU, produced a vertical plume 5 - 10 m thick and an annulus with a radial dimension of
232 m. Increased turbidity was measured 475 m from the point dump. A vertical plume 13
m thick was measured at Cell LD, which was capped using the spreading technique;
however, within 2 minutes plume thickness had decreased 50 percent (SAIC, 2002).
Turbidity associated with the spreading technique dissipated faster than turbidity from
point dump placement.
Post-cap monitoring observed a depositional layer of fine-grained sediment over all three
caps. Sediment cores were collected across the caps. For the LU cell at 40 m, contaminant
concentrations in the 0-8 cm surface layer were generally lower than pre-capping
concentrations. However, in three of seven cores, DDE concentrations in the top 0-4 cm
layer higher than those in the 4-8 cm layer. For the LD cell, which was capped using the
spreading method, only two cores were taken; however, core profiles of sediment DDE
concentrations did not show any consistent depth pattern and concentrations generally
were comparable to baseline conditions. The SU cell, which was in deeper water than the
other two cells and would be included in Grid Cell 7C, had the most unsatisfactory results.
None of the four sediments cores collected from the SU cell had a visually distinct
cap/sediment interface. Geotechnical measurements and sediment chemistry indicated
mixing of EA sediment with cap material. In some cores, surface (0 -4 cm) DDE
concentrations were comparable to or higher than baseline values. Core profiles exhibited a
pattern of DDE decreasing concentrations with core depth. In two of the cores, DDE
concentration peaked in the 0-4 cm interval; in the other two cores the peak was in the 12-16
cm interval (SAIC, 2002). In contrast, pre-capping cores historically had peak concentrations
occurring at depths of 25 to 45 cm. The post-cap monitoring suggests erosion/scouring of
surface sediment occurred (SAIC, 2002). In assessing these post-pilot capping data, it is
important to keep in mind that point placement was used for Cells LU and SU, the pilot
cells were much smaller than the proposed cap area(s) and had target cap thicknesses of 15
to 18 cm. Nevertheless, the pilot project illustrated the potential difficulties associated with
capping soft sediment at 40 to 60 m depths.
Under this alternative, risk also would be reduced over time through natural attenuation.
Monitoring would be required to determine actual long-term effectiveness of a cap and of
natural recovery. The institutional controls component can be effective in reducing the
number of contaminated fish being eaten by consumers, but it does not reduce the risk to
/MAY09PVS CHART 5.DOC 5-33
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
fish or other ecological receptors. Alternative 4 includes monitoring to assess the impact of
natural processes on the recovery of the PV Shelf Study Area.
Implementability. The depth of water, the large areal extent of the effluent-affected sediment,
and the potential for resuspension of the effluent-affected sediment during cap placement
make the implementation of a sand cap in Alternative 4 difficult. The materials and services
for Alternative 4 are readily available.
Cost. The cost of Alternative 4 is high due to cap material, conveyance/transport, cap
placement, and monitoring costs.
5.3.5 Alternative 5—Removal with Monitored Natural Recovery and Institutional
Controls
Effectiveness. The effectiveness of this technology is low. Hydraulic dredging is a proven
technology for removal of ocean sediment but is done rarely at these depths. Because of
restrictions on use of foreign vessels in U.S. waters, it is unclear whether a trailing suction
hopper dredge that operates at the required depth of 60 to 70 m would be available. The
volume of material would require an estimated 12 years to dredge, in part because the open
ocean location would limit the operational season to six or seven months. The volume of
dredged material would be difficult to manage. Although hydraulic dredging has a
favorable rating for resuspension, the amount of EA sediment mobilized by dredging would
be significant.
Implementability. In theory, Alternative 5 is implementable. However, there are site-specific
issues related to technical and administrative implementability that may render this
alternative infeasible. This section discusses the technical and administrative feasibility, and
the availability of services and materials.
Technical Feasibility. Deep-water dredging is difficult. Dredging would cause some
resuspension of the EA sediment, which would be difficult to manage. The volume to be
dredged would be approximately 1,233,000 m3 or 1,613,000 yd3. The dragline of the trailing
suction hopper dredge is more difficult to control at deep-dredge depths, especially under
ocean currents and with long drag-arms. Overlapping passes would be required, which
could result in increased turbulence and increase volume of dredged material. A
comprehensive monitoring and maintenance program would be required. The estimated
total quantity of material to be dredged is approximately 10,640,000 yd3, and the scow
capacities are 2,000 yd3; therefore, dredging would be a multi-year operation.
Technical feasibility of thermal desorption is moderate for the site. There are many factors
that can limit the implementability and effectiveness of thermal desorption. High moisture
contents require more energy to reach temperatures necessary for destruction of
contaminants so a suitable source of electric power is needed. When moisture content is
higher than 20 percent, impacts on cost become significant (USEPA, 1997a). In addition, the
solids content of the material must be at least 20 percent for effective treatment (USEPA,
1992). Additionally, the pH of the material must be monitored to ensure that corrosion does
not occur within the system. The removal efficiency and residence time necessary to
achieve treatment standards will be affected by the contaminant concentrations and
moisture content of the material (EPA, 1992).
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
Transportation of the dredged material to the proposed unloading areas could cause issues
with ship traffic. Another issue affecting technical implementability is whether adequate
space is available for stockpiling treated and untreated materials, dewatering materials, and
operating process equipment. The lack of open spaces near PV Shelf may indicate
significant limitations to implementability of this alternative.
Dewatering cells are easily constructed; however, available open space near PV Shelf is
limited. The shoreline and upland areas are highly developed or public spaces, i.e., beaches
and parks. The most likely location is within the Ports of Los Angeles or Long Beach, which
are located approximately 5 nautical miles from the dredge site. The Port of Los Angeles
has infrastructure for truck traffic already in place along with level topography suitable for
dewatering cell construction. However, the availability of port areas is unknown and port
operations may preclude their use.
Treatment and disposal of water from dredging and sediment dewatering would require a
mobile water treatment facility equipped with pumps, pre-filtration equipment, and GAC
units.
Administrative Feasibility. Administrative feasibility for dredging operations would be difficult
as these activities would require coordination with the Port of Los Angeles and the U.S.
Coast Guard for dredging near the port and for use of the Port for sediment offloading,
dewatering, and treatment. In addition, the Jones Act requires that only U.S. vessels be used
for dredging and transporting dredged material in U.S. waters.
Administrative feasibility for construction of dewatering cells and a water treatment plant is
considered low. These facilities would require approval from multiple state and local
agencies. Permits may be required by local authorities for operation and monitoring and
limits on hours of operation or noise control measures, may be required.
The volume of material after dewatering is estimated to be approximately 3,610,000 yd3. A
large number of trucks would be required to transport the treated material to an approved
off-site disposal facility. Truck traffic is already an issue with the ports, and it is unclear
whether port plans to control air emissions from trucks would accommodate the extra
capacity that would be needed.
Cost. The cost of this technology is high due to the amount of sediment and water that
would need to be managed and disposed. A feasible disposal option for the dredged
material would need to be developed. The EPA Office of Water has indicated that ocean
disposal of the effluent-affected sediment from the PV Shelf would not be allowed (Ross,
2007). Therefore, the dredged material would require disposal at an upland site after
treatment to meet State of California disposal standards for DDT.
Removal, treatment, and disposal would cost over $2 billion. Questions about the
effectiveness and implementability of removal, in addition to cost, cause this technology to
be rejected from further consideration.
5.4 Summary of Retained Alternatives
Based on an evaluation of the assembled and developed alternatives, alternatives 1 thru 4
are retained for detailed analysis. Alternative 1 is retained because the no action alternative
is required as a baseline for comparison with other remedial action alternatives in
accordance with the NCP. Alternative 2, Institutional Controls with Monitored Natural
/MAY09PVS CHART 5.DOC 5-35
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5.0 DEVELOPMENT AND SCREENING OF ALTERNATIVES
Recovery, is retained because it will protect human health by reducing consumption of
contaminated fish and assess the rate of natural recovery processes known to be occurring at
the site. Alternative 3 is retained because, in addition to protecting human health through
institutional controls, it will accelerate the natural recovery known to be occurring at the site
by reducing exposure and contaminant flux from the area of highest COCs. Alternative 4 is
retained because it combines the elements of each alternative, reducing risk to human health
from consumption of fish, monitoring natural recovery processes, and reducing the risk to
the biological community and concentrations in the surface water by isolating sediment
with high concentrations of DDTs and PCBs.
5-36 MAY09PVS CHART 5.DOC
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
6.0 Detailed Analysis of Remedial Alternatives
6.1 Introduction
This section provides a detailed analysis of the alternatives developed in Section 5.0 for
remediation of contaminated sediment in the effluent-affected area of the PV Shelf Study Area.
As discussed in section 5.0, this feasibility study is for an interim record of decision. The
alternatives discussed below are interim remedies that will be supplemented by additional
measures after further studies and analysis of the remedy's effectiveness. The four alternatives
are evaluated according to the standard criteria specified in the Guidance for Conducting Remedial
Investigations and Feasibility Studies under CERCLA (USEPA, 1988a). Each alternative is
evaluated individually against each criterion, followed by a comparison among alternatives to
assess specific strengths and weaknesses that must be balanced.
The nine CERCLA evaluation criteria are in the following list:
1. Overall protection of human health and the environment
2. Compliance with ARARs
3. Long-term effectiveness and permanence
4. Reduction of toxicity, mobility, or volume through treatment
5. Short-term effectiveness
6. Implementability
7. Cost
8. State acceptance
9. Community acceptance
The NCP, 40 CFR Section 300.430(e)(9)(iii)/ categorizes these nine criteria into three types: (1)
threshold criteria, (2) primary balancing criteria, and (3) modifying criteria. Each alternative
must meet the threshold criteria to be eligible for selection as the preferred alternative. The two
threshold criteria are (1) protection of human health and the environment and (2) compliance
with ARARs (unless a waiver is obtained).
Primary balancing criteria are used to weigh effectiveness and cost tradeoffs among
alternatives. The five primary balancing criteria include (1) long-term effectiveness and
permanence; (2) reduction of toxicity, mobility, or volume through treatment; (3) short-term
effectiveness; (4) implementability; and (5) cost. The primary balancing criteria represent the
main technical criteria upon which alternative evaluation is based.
Modifying criteria are state acceptance and community acceptance, and may be used to modify
aspects of the preferred alternative when preparing the Record of Decision (ROD) for the
remedial alternative. Modifying criteria are generally evaluated after public comment on the FS
and the proposed plan.
These nine evaluation criteria are intended to provide a framework for assessing the risks, costs
and benefits for each remedial alternative. The relative performance of each alternative is
assessed individually and comparatively with respect to the evaluation criteria in order to
identify the key tradeoffs among them. Only the two threshold and the five primary balancing
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
criteria are used to evaluate alternatives in the detailed analysis phase. The following
subsections contain descriptions of these seven evaluation criteria, individual evaluations of the
alternatives, and a comparative evaluation. Descriptions of the individual alternatives are
provided in Section 5.0.
6.2 Threshold Criteria
Threshold criteria serve as essential determinations that should be met by any remedial
alternative in order to be eligible for selection. They serve as primary project goals for a
remediation program.
6.2.1 Overall Protection of Human Health and the Environment
This evaluation criterion assesses how each alternative provides and maintains adequate
protection of human health and the environment. Alternatives are assessed to determine
whether they can adequately protect human health and the environment from unacceptable
risks posed by contaminants present at the site, in both the short and long term. This criterion is
also used to evaluate how risks would be eliminated, reduced, or controlled through treatment,
engineering, institutional controls, or other remedial activities.
As discussed in Section 2.0, the primary risk to human health associated with the contaminated
sediment is consumption of fish. The primary risk to the environment is direct ingestion of
sediment by invertebrates and bioaccumulation of COCs in higher trophic species from the
consumption of invertebrates, fish, or piscivorous birds. Protection of human health and the
environment is evaluated by estimating the timeframe required 1) to reduce COC sediment
loads and improve surface water quality; 2) to reduce COC concentrations in fish to allow safe
consumption of fish; and 3) to reach surface sediment concentrations protective of local,
benthic-feeding fish.
The key remedial thresholds evaluated during the analysis of each alternative for overall
protection of human health and the environment are presented in Table 6-1.
TABLE 6-1: OVERALL PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
Goal Considerations
Human Health Likelihood that the alternative meets RAOs to reduce risk to human health from
Protection consumption offish contaminated with DDTs and PCBs, defined as achieving an
acceptable risk level:
400 ug/kg DDT and 70 ug/kg PCBs
• Estimated COC concentrations in sediment necessary to achieve above
concentrations in white croaker are 230 ug/kg DDT and 70 ug/kg PCBs at 1%
total organic carbon
and Ambient Water Quality Criteria for protection of human health from contaminants in
fish:
• 0.22 ng/L DDT and 0.064 ng/L PCBs
Protection of " Likelihood that the alternative meets RAOs to reduce risk to ecological receptors,
Ecological defined as Ambient Water Quality Criteria for protection of ecological receptors:
Receptors . 1 ng/L DDT
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
6.2.2 Compliance with Applicable or Relevant and Appropriate Requirements
This evaluation criterion is used to determine if each alternative would comply with federal and
state ARARs, or whether invoking waivers to specific ARARs is adequately justified. Other
information, such as advisories, criteria, or guidance, is considered where appropriate during the
ARARs analysis. Considerations evaluated during the analysis of the ARARs applicable to each
alternative are presented in Table 6-2. Potential action-, location-, and chemical-specific ARARs
for the alternatives presented in this FS are identified in Section 3.0.
TABLE 6-2: COMPLIANCE WITH APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
Analysis Factors Considerations
Chemical-specific ARARs Likelihood that the alternative will achieve compliance with chemical-specific
ARARs such as of EPA's ambient water quality criteria for DDTs and PCBs
(see Table 6-1) within a reasonable period of time
Evaluation of whether a waiver is appropriate if the chemical-specific ARARs
cannot be achieved
Location-specific ARARs Determination of whether any location-specific ARARs, such as the
Endangered Species Act, apply to the alternative
Likelihood that the alternative will achieve compliance with any location-specific
ARAR
Evaluation of whether a waiver is appropriate, if the location-specific ARAR
cannot be met
Action-specific ARARs Likelihood that the alternative will achieve compliance with potential action-
specific ARARs, such as MPSRA.
Evaluation of whether a waiver is appropriate, if the action-specific ARAR
cannot be met
Other Criteria and Likelihood that the alternative will achieve compliance with other criteria
Guidance (e.g., risk-based criteria)
6.3 Balancing Criteria
Balancing criteria are included in the detailed analysis of alternatives because these five
variables (long-term effectiveness, reduction of toxicity, short-term effectiveness,
implementability, and cost) are important components that often define the major trade-offs
between alternatives. They serve as important elements of project goals that require careful
consideration for successful implementation and long-term success of remediation. The five
balancing criteria are evaluated for each remedial alternative. The following subsections
provide description of the criteria evaluated in this portion of the detailed analysis.
6.3.1 Long-Term Effectiveness and Permanence
This evaluation criterion addresses long-term effectiveness and permanence of the protection of
human health and the environment after implementing the remedial action imposed by the
alternative. The primary components of this criterion are the magnitude of residual risk
remaining at the site after RAOs have been met, and the extent and effectiveness of controls that
might be required to manage the risk posed by treatment residuals and/or untreated wastes.
For example, important considerations for long-term effectiveness under Alternative 4, which
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
includes capping, would include physical stability of the cap, the depth of bioturbation and
potential recontamination. Considerations evaluated during the analysis of each alternative for
long-term effectiveness and permanence are presented in Table 6-3.
TABLE 6-3: LONG-TERM EFFECTIVENESS AND PERMANENCE
Analysis Factors
Considerations
Magnitude of Residual Risks
Adequacy and Reliability of
Controls
Identification of remaining risks from treatment residuals, as well as from
untreated residual contamination
Magnitude of remaining risks
Likelihood that the technologies will meet required process efficiencies or
performance specifications
Type and degree of long-term management required
Long-term monitoring requirements
O&M functions that must be performed
Difficulties and uncertainties associated with long-term O&M functions
Potential need for technical components replacement
Magnitude of threats or risks, should technical components need
replacement
Confidence that controls can adequately handle potential problems
Uncertainties associated with land disposal of residuals and untreated
wastes
6.3.2 Reduction of Toxicity, Mobility, or Volume through Treatment
This evaluation criterion addresses the anticipated performance of the alternative's treatment
technologies to permanently and significantly reduce toxicity, mobility, and/or volume of
hazardous materials at the site. The NCP states a preference for remedial actions in which
treatment is used to reduce the principal threats at a site through destruction of toxic
contaminants, irreversible reduction in contaminant mobility, or reduction of total volume of
contaminated media. None of the alternatives involve treatment, but it is expected that the
toxicity, mobility, and volume will be reduced in each alternative to some extent over time by
natural degradation processes. Considerations evaluated during the analysis of each alternative
for reduction of toxicity, mobility, or volume of contaminants present at a given site are
presented in Table 6-4.
TABLE 6-4: REDUCTION OF TOXICITY, MOBILITY, OR VOLUME THROUGH TREATMENT
Analysis Factors
Considerations
Treatment Process and Remedy
Amount of Hazardous Material
Destroyed or Treated
Reduction in Toxicity, Mobility, or
Likelihood that the treatment process addresses the principal threat
Special requirements for the treatment process
Portion (mass) of contaminant that is destroyed
Portion (mass) of contaminant that is treated
Extent to which the total mass of contaminants is reduced
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
TABLE 6-4: REDUCTION OF TOXICITY, MOBILITY, OR VOLUME THROUGH TREATMENT
Analysis Factors
Considerations
Volume through Treatment
Irreversibility of Treatment
Type and Quantity of Treatment
Residual
Statutory Preference for
Treatment as a Principal Element
Extent to which the mobility of contaminants is reduced
Extent to which the volume of contaminants is reduced
Extent to which the effects of the treatment are irreversible
Types of residuals that will remain
Quantities and characteristics of residuals
Risks posed by residuals
Extent to which the scope of the action covers the principal threats
Extent to which the scope of the action reduces the inherent hazards
posed by the principal threats
6.3.3 Short-Term Effectiveness
This evaluation criterion considers the effect of each alternative on the protection of human
health and the environment during the construction and implementation process. The short-
term effectiveness evaluation only addresses protection prior to meeting the RAOs. An
important short-term consideration at the PV Shelf Study Area is the resuspension of
contaminated sediment during implementation of the capping alternative. Considerations
evaluated during the analysis of each alternative for short-term effectiveness are presented in
Table 6-5.
TABLE 6-5: SHORT-TERM EFFECTIVENESS
Analysis Factors
Considerations
Protection of the Community During
the Remedial Action
Protection of Workers During Remedial
Actions
Environmental Impacts
Time until RAOs are Achieved
Risks to the community that must be addressed
How risks will be addressed and mitigated
Remaining risks that cannot be readily controlled
Risks to workers that must be addressed
How risks will be addressed and mitigated
Remaining risks that cannot be readily controlled
Types of environmental impacts expected during construction and
implementation of the alternative (e.g., resuspension of
contaminated sediments)
Available mitigation measures and their reliability to minimize
potential impacts
Unavoidable impacts, should the alternative be implemented
Time needed to achieve protection against the risks being
addressed
Time needed to address any remaining risks
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
6.3.4 Implementability
This criterion evaluates the technical and administrative feasibility (i.e., the ease or difficulty) of
implementing each alternative, and the availability of required services and materials during its
implementation. In addition to its sheer size, the PV Shelf Study Area poses unique challenges
for implementing remedial actions including the depth of water, physical characteristics of the
effluent-affected sediment, and slope. Considerations evaluated during the analysis of each
alternative for implementability are presented in Table 6-6.
TABLE 6-6: IMPLEMENTABILITY
Analysis Factors
Considerations
Technical Feasibility
Ability to Construct and Operate the
Technology
Reliability of the Technology
Ease of Undertaking Additional Remedial
Action
Monitoring Considerations
Difficulties associated with construction (e.g., water depth)
Uncertainties associated with construction
Likelihood that technical problems will lead to schedule delays
Likely additional remedial actions
Difficulty implementing additional remedial actions
Migration or exposure pathways that cannot be monitored
adequately
Risks of exposure, should monitoring be insufficient to detect
failure
Administrative Feasibility
Coordination with Other Agencies
Steps required to coordinate with regulatory agencies
Steps required to establish long-term or future coordination
among agencies
Ease of obtaining permits for offsite activities, if required
Availability of Services and Materials
Availability of Treatment, Storage
Capacity, and Disposal Services
Availability of Necessary Equipment and
Specialists
Availability of Prospective Technologies
Availability of adequate treatment, storage capacity, and disposal
services
Additional treatment, storage, and disposal capacity that are
necessary
Whether lack of capacity prevents implementation
Additional provisions required to ensure additional capacity is
available
Availability of adequate equipment and specialists
Additional equipment or specialists that are required
Whether there is a lack of equipment or specialists
Additional provisions required to ensure that equipment and
specialists are available
Whether technologies under consideration are generally
available and sufficiently demonstrated
Further field applications needed to demonstrate that the
technologies could be used full-scale to treat the waste at the
site
When technology should be available for full-scale use
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
Whether more than one vendor will be available to provide a
competitive bid
6.3.5 Cost
This criterion evaluates the cost of implementing each alternative. The cost of an alternative
encompasses capital costs (engineering, construction, and supplies) and annual or periodic costs
(O&M costs, monitoring, and ongoing administration) incurred over the life of the remedial
action. Capital costs are incurred during implementation and startup of the remedy. Annual
costs are those costs required to maintain the operation of the remedy over time. According to
CERCLA guidance (EPA, 1988a), cost estimates for remedial alternatives were developed with
an expected accuracy range of -30 to +50 percent.
The costs of remedial alternatives are compared using the estimated present value of the
alternative. The net present value allows costs for remedial alternatives to be compared
by discounting all costs to the year that the alternative is implemented. In the Guide to
Developing and Documenting Cost Estimates During the Feasibility Study (EPA, 2000), EPA suggests
that the period of analysis for the present value analysis should be equivalent to the project
duration, to provide a complete life cycle cost estimate of the remedial alternative. Most of the
remedial alternatives developed for the PV Shelf Study Area require long-term activities,
including sediment and fish monitoring; enforcement of fishing restrictions; and maintenance of
constructed caps and covers.
The costs of the remedial alternatives are compared using the estimated present value and the
total accumulated cost of the alternative. The net present value (NPV) allows costs for remedial
alternatives to be compared by discounting all costs to the year that the alternative is
implemented. For all alternatives, the NPV was calculated using a discount rate of
seven percent as stated in preamble to the NCP, 55 FR 8722, and the Office of Solid Waste and
Emergency Response (OSWER) Directive 9355.3-20 entitled "Revisions to OMB Circular A-94
on Guidelines and Discount Rates for Benefit-Cost Analysis" (EPA, 2000). This specified rate of
seven percent represents a "real" discount rate in that it approximates the marginal pretax rate
of return on an average investment in the private sector in recent years and has been adjusted to
eliminate the effect of expected inflation. Indirect costs including bid and scope contingency,
project management, remedial design, and construction management/field activity oversight
were added to capital costs as percentages of the total cost. Percentages were determined based
on the uncertainty, total cost, and/or complexity of the project. Annual costs were also marked
up with bid and scope contingencies. Other indirect costs applicable to annual costs such as
project management and technical support were included as separate labor estimates. Detailed
cost estimates and cost estimate assumptions are provided in Attachment 1.
The technology or design features assumed in the scope and cost estimate may not necessarily
be those implemented in the final design.
6.4 Detailed Analysis of Alternatives
In Section 5.0, the following four alternatives were assembled, developed, and retained for
detailed analysis:
• Alternative 1 - No Action
• Alternative 2 - Institutional Controls with Monitored Natural Recovery
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
• Alternative 3 - Small Cap Containment with Institutional Controls and Monitored Natural
Recovery
• Alternative 4 - Large Cap Containment with Institutional Controls and Monitored Natural
Recovery
This section presents the evaluation of each remedial alternative against the two threshold
criteria (overall protection of human health and the environment and compliance with ARARs)
and the balancing criteria (long-term effectiveness and permanence; reduction of toxicity,
mobility, or volume through treatment; short-term effectiveness; implementability; and cost).
Table 6-8 at the end of this section summarizes each alternative and Attachment 1 provides cost
details for each alternative over a 10-year project duration.
6.4.1 Alternative 1 - No Action
The No Action alternative provides a baseline from which to analyze other alternatives. This
alternative does not include any active remediation, monitoring, or institutional controls.
Threshold Criteria
Since no active remediation would be undertaken, the site would remain in its current state,
with only natural processes causing change. Based on the sediment transport and food web
models, "no action" would not meet protectiveness criteria, including ARARs (i.e., the AWQC),
for over 30 years. It is unlikely that fish tissue concentrations for bottom-feeders like white
croaker, would reach RME protectiveness levels for 50 years. Routine monitoring would not
take place.
6.4.1.1 Overall Protection of Human Health and the Environment
Alternative 1, the No Action alternative, would not control the current risk to human health or
to the environment. As discussed in Section 2.0, consumption of fish caught from the PV Shelf
Study Area, particularly bottom feeders like white croaker, posed a health risk because of their
high levels of DDTs and PCBs. Because the No Action alternative does not include institutional
controls or monitoring to limit human exposure to contaminated fish, it would not protect
human health until natural processes reduce contaminant concentrations in fish to acceptable
levels.
6.4.1.2 Compliance with Applicable or Relevant and Appropriate Requirements
Existing site conditions do not comply with the ambient water quality criteria (AWQC) for
protection of human health. Waters overlying the shelf contain concentrations of DDTs and
PCBs that exceed the EPA AWQC of 0.22 ng/L DDT and 0.064 ng/L PCBs (Zeng et al, 1999) for
protection of human health and the AWQC for ecological health of 1 ng/L DDT. It is estimated
that the waters of PV Shelf will meet human health AWQC for DDT in 30 to 60 years (Appendix
B). Insufficient data are available to predict when the human health AWQC for PCBs would be
attained.
Balancing Criteria
6.4.1.3 Long-Term Effectiveness and Permanence
Under the No Action Alternative, untreated contamination in sediment would continue to pose
a potential risk to human health and the environment through bioaccumulation. Although
DDT and PCB concentrations in sediment have dropped, concentrations in fish continue to
6-8
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
exceed safe consumption guidelines. Remediation goals for COC concentrations in fish (400
DDTs and 70 Mg/kg PCBs in white croaker) would not be met for 50 years.
DDT concentrations in sediment do not meet SEC values for protection of invertebrates at the
outfall area and portions of the slope, although median concentrations for PV Shelf sediment
meet SEC values. PCB concentrations in sediment already meet the SEC goal.
Risk to both human health and ecological receptors would remain until fate-and-transport
processes reduce the concentrations below levels of concern. Because no monitoring would be
conducted under this alternative, the rates of the natural recovery processes would not be
tracked.
6.4.1 .4 Reduction of Toxicity, Mobility, or Volume through Treatment
There would be no reduction of toxicity, mobility, or volume through treatment with this
alternative, because no remedial action would be implemented. Some permanent reduction in
toxicity, mobility, or volume would occur through natural recovery processes over a period of
time at the site. However, the significance and rate of natural recovery processes would not be
assessed because no monitoring would be conducted under this alternative.
6.4.1 .5 Short-Term Effectiveness
Because no remedial action, including institutional controls, is included under Alternative 1,
short-term effectiveness would be lower than under the existing institutional controls program.
No additional short-term risks to the community or to workers would occur as a result of
implementing the alternative. Similarly, no environmental impact from implementation
activities would occur.
6.4.1.6 Implementability
Implementability of Alternative 1 would not be applicable as, by definition, no action would
take place. No monitoring would be performed, no institutional controls would be
implemented, and no construction would occur under this alternative.
6.4.1.7 Cost
Because Alternative 1 assumes no further action, there would be no cost associated with its
implementation.
6.4.2 Alternative 2 - Institutional Controls with Monitored Natural Recovery
Alternative 2, Institutional Controls, is intended to reduce risks to human health associated with
consumption of contaminated fish from the PV Shelf Study Area through non-engineered
controls while monitoring natural processes that contribute to the recovery of the site. Under
this alternative, ICs remain in place until RAOs are met. A long-term monitoring plan will
verify natural recovery rates.
Institutional controls have been in place at the PV Shelf since the State of California first issued
fish advisories and health warnings in 1985. EPA's Action Memorandum (2001) created the
current institutional controls program, which consists of three components: public outreach and
education, enforcement, and fish monitoring. The institutional controls program relies heavily
on partnerships with other federal, state, and local agencies, and community-based
organizations. Under Alternative 2, EPA's current institutional controls program would be
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
strengthened by increasing ocean-to-market monitoring. Existing State of California fish
advisories and catch ban would remain in place.
Although there have been numerous studies of PV Shelf, the only regular monitoring that
occurs is that of LACSD under its NPDES permit. Under this alternative, EPA would institute a
monitoring program to track reductions in concentrations of COCs in fish, water and sediment.
Subsection 5.2.2.4 discusses monitoring for natural recovery. Appendix D presents the current
draft institutional controls implementation plan.
Threshold Criteria
According to EPA guidance (EPA, 2005), natural recovery is an appropriate remedy at sites
where the levels of contamination are relatively low, the area of contamination is large, and
natural recovery is proceeding at a high rate. As discussed in Section 2.0, these criteria are met
for some—but by no means all —of PV Shelf. Median PCB concentrations in surface sediment
are 200 Mg/kg (CH2M Hill, 2007). Sediment transport modeling predicts DDT concentrations
in sediment will fall below 1000 Mg/kg in approximately 15 years, except for the outfall area,
where concentrations are likely to increase (Sherwood, 2002). Median DDT concentrations are
predicted to fall below 200 j-ig/kg by 2053.
6.4.2.1 Overall Protection of Human Health and the Environment
Institutional controls reduce the risks to human health associated with the consumption of
contaminated fish through public outreach, education and enforcement programs. However,
institutional controls do not directly reduce contaminant levels in fish.
The education component of the existing institutional controls program has increased
awareness and understanding of the fish consumption advisories and commercial fishing
restrictions. However, monitoring and analysis of fish for sale in Los Angeles County and
Orange County markets indicate that contaminated fish are still available to consumers.
Since Alternative 2 relies on natural recovery processes to reduce risk, ecological receptors
would continue to be exposed to contamination in sediment and water. Although natural
recovery has reduced the risk to ecological receptors from PCBs, birds and sea lions would
continue to be at risk from DDT through consumption of contaminated fish for many years.
Institutional controls would not affect whether or not fish accumulate DDTs and PCBs to levels
that exceed federal or state criteria for human consumption, although effective enforcement of
the commercial fishing ban and the daily bag limit would tend to reduce the likelihood that
such fish could turn up in retail fish markets.
DDT concentration in sediment is expected to fall below 200 Mg/kg in approximately 45 years.
As described in Appendix C, depending on organic carbon in sediment and lipid content in
fish, 230 Mg/kg is correlated with the goal of 400 Mg/kg DDT in fish tissue.
6.4.2.2 Compliance with Applicable or Relevant and Appropriate Requirements
Existing site conditions do not comply with human health ARARs (Zeng et al., 1999). Waters
overlying the shelf contain concentrations of DDTs and PCBs that exceed the EPA ambient
water quality criteria (AWQC) for human health: 0.22 ng/L DDT and 0.064 ng/L PCBs and the
AWQC for protection of ecological receptors, 1 ng/L DDT.
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
Human Health ARAR for DDT is forecasted to be met in 30 to 60 years. As discussed under the
No Action alternative, the rate of recovery depends on a number of variables that affect water
quality.
Balancing Criteria
6.4.2.3 Long-Term Effectiveness and Permanence
As discussed in the No Action alternative, PV Shelf is undergoing natural recovery, which over
time will reduce contaminant concentrations to levels protective of human health and ecological
receptors. In the interim, institutional controls can reduce but not completely prevent human
exposure to DDTs and PCBs via fish consumption. A study conducted in the early 1990s, before
implementation of EPA's current institutional controls (ICs) program, found that 77 percent of
anglers (boat and shore-based anglers) were aware of the health warnings, but only 50 percent
of them altered their consumption habits (SMBRP, 1994). The ICs program has been successful
in altering behavior, but relies on angler cooperation—which is not entirely reliable— to control
risk.
Similarly, the enforcement component of institutional controls has been largely, but not
completely, successful. Visits to fish markets in Los Angeles and Orange counties, discussed
below, found few markets selling white croaker. However, among the few white croaker
found, most exceeded the remediation goals for PCBs and DDT in fish fillet. While enforcement
appears to have limited the number of white croaker reaching fish markets, it clearly has not
succeeded in eliminating the risk of contaminated fish reaching commercial outlets. Alternative
2 would increase market monitoring and pursue additional ocean-to-market enforcement to
increase the long-term effectiveness.
Since contaminant concentrations are dropping in sediment and water, concentrations in fish
are dropping as well. Remediation goals for white croaker should be met in 50 years and sooner
for other fish that aren't local bottom-feeders.
Results of Current Education/Outreach Programs
The education component of the existing institutional controls program was initiated in 2002
and has been effective in informing thousands of community members about contaminated fish
from the PV Shelf Study Area. The EPA created the Fish Contamination Education
Collaborative (FCEC) to bring together interested agencies, groups, and community-based
organizations to design and implement an outreach program to address the health risks from
eating contaminated fish related to the PV Shelf Study Area. The FCEC has developed outreach
program components targeting anglers, market owners, and families who consume locally
caught fish. The outreach efforts have been conducted in numerous languages including
English, Spanish, Cambodian, Chinese, Filipino, Korean, Vietnamese, Chamorro, Samoan,
Marshallese, and Tongan.
From 2003 to 2005, the institutional controls angler outreach program reached 33,753 anglers
at eight popular fishing piers in Los Angeles and Orange counties: Belmont, Cabrillo, Pier J,
Seal Beach, Santa Monica, Hermosa, Redondo, and Venice. The outreach effort included
training community members to go to the piers to inform anglers about the fish contamination
history, fish advisories, identification of contaminated fish, fish they could safely eat and how
much, and how the anglers could prepare the fish to reduce their risk of exposure. Of the
anglers that had previously been outreached, 97 percent indicated some type of behavior
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
modifications based on the outreach message (e.g., change fishing spots, throw fish back and/or
stop or reduce amount of white croaker consumption).
From 2003 to 2005, community members or county environmental health inspectors contacted
328 fish markets, restaurants, or wholesalers for the commercial fish program. The outreach
effort relies on community members trained to go to markets and restaurants to inform the
owners and/or managers about the PV Shelf Study Area fish contamination and to recommend
purchasing fish only from licensed wholesalers, brokers, or commercial fishermen; to know
where the fish are caught; and to keep invoice records when fish are purchased.
From 2003 to 2005, the FCEC program reached more than 100,000 people through 4,668
community fairs, health fairs, and other forms of outreach sessions. Community-based educators
from the most affected communities were trained to create and conduct in-language health
education around the PV Shelf Study Area fish contamination issues in their communities. Local
health departments also serve as partners in disseminating information. Of those who attended
training workshops, 91 percent expressed intent to modify fish consumption behavior due to the
information received during outreach sessions.
Enforcement of Institutional Controls
The institutional controls program includes enforcement of existing state fishing regulations by
the appropriate state agencies (white croaker bag limit for sports fishing and white croaker
catch ban for commercial fishing). State agencies have increased enforcement when warranted.
In 1997, CDFG documented a problem with the commercial sale of sport-caught white croaker
in Los Angeles and Orange counties, including fish caught in areas where the health advisories
recommend no consumption of white croaker. In response, CDFG instituted a daily bag limit
on white croaker in 1998.
Keeping the commercial catch ban boundaries current presents a challenge. The 2002/2004 fish
contaminants survey (EPA/MSRP 2007) found some white croaker caught outside the catch ban
area had concentrations of DDTs and PCBs equal to and even higher than those caught inside
the catch ban. Commercial fishermen could inadvertently catch and sell contaminated white
croaker outside the current catch ban area. The State OEHHA is evaluating recent fish survey
data to assess whether the boundaries of the white croaker catch ban zone are sufficient or need
to be expanded, and to update the fish consumption advisories. Enforcement and monitoring
of commercial and recreational fishing at the PV Shelf and adjacent areas is performed by
CDFG.
EPA undertook a market fish survey in part to evaluate the effectiveness of the catch ban and
bag limit and to assess whether contaminated white croaker are being sold in retail fish
markets. In 2004 and 2005, EPA visited 68 markets a total of 135 times and found only six
markets that carried white croaker (30 fish total). However, white croaker from all of the
markets contained detectable levels of COCs, and some white croaker in all of the six markets
exceeded remediation goals as well. Concentrations of DDTs and PCBs in fish tissue were as
high as 11,800 Mg/kg and 970 Mg/kg, respectively. The market fish survey demonstrated that
few markets carry white croaker, but that white croaker with unacceptably high concentrations
of contaminants can still be found in the markets that do carry the fish. The suppliers of white
croaker to the markets have not been determined, nor has it been determined if the
contaminated white croaker were caught within the commercial catch ban area or in other
locations.
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
As a result of EPA's fish market survey, EPA CDFG and the Los Angeles and Orange counties'
environmental health inspection agencies have developed a white croaker market inspection
component for the enforcement program. The goal is to stop contaminated white croaker from
reaching consumers through enforcement and outreach by CDFG wardens and county
inspectors. Data collected by the inspectors provide baseline information on white croaker
availability and their suppliers. Alternative 2 would strengthen the market monitoring program
and strengthen outreach to, and monitoring of, wholesale markets and distributors.
Monitored Natural Recovery
The natural recovery monitoring component of Alternative 2 would track reductions in
contaminant concentrations in fish, sediment, and water. Natural recovery will likely consist of
reduction in risk through a combination of the following:
• Burial of effluent-affected sediment below the biologically active zone
• Mixing of cleaner sediment with effluent-affected sediment
• Transport of contaminants offsite through natural processes
• Conversion of DDE to a less harmful form
• Reduction of contaminant bioavailability to receptors through changes in the resident
biological communities (including microbial)
An estimated 7 percent of the DDE (the principal DDT isomer remaining in the sediment) in the
sediment is lost annually through natural processes (Sherwood et al. 2006). Sediment cores
collected at Stations 3C and 6C for over 20 years show a significant reduction in the DDE
inventory from the early 1980s to the early 2000s (Sherwood et al., 2006). Sediment core data
collected for investigation from two sites has shown that the inventory of DDE has decreased
while that of DDMU has increased (Eganhouse and Pontolillo, 2007). Surface sediment
concentrations have also decreased significantly over the last 15 years (Table 1-1). However,
further studies are necessary to determine whether the DDE daughter products are less toxic
than DDE, and whether or not surface reductions in contaminant concentrations are permanent
and not subject to future erosion. The USGS is investigating the reductive dechlorination of DDE
to identify the causes and estimate degradation rates throughout the EA sediment deposit.
Analysis of oceanographic data collected during Winter 2007-08 will allow USGS to complete
their model of sediment transport that will answer the question regarding rates and locations of
potential erosion.
6.4.2.4 Reduction of Toxicity, Mobility, or Volume through Treatment
There would be no reduction of toxicity, mobility, or volume through treatment with this
alternative, because no treatment would be implemented. Some permanent reduction in
toxicity, mobility, or volume would occur through natural recovery processes at the site over a
period of time.
6.4.2.5 Short-Term Effectiveness
To the degree that Alternative 2 implements additional ICs programs targeting ocean-to-market
fish monitoring, further reductions in short-term risks for fish consumers is possible.
No risks of exposure to site-related contaminants will occur for the workers. Implementation of
the institutional controls program, including sampling fish, would present a slight risk to
workers due to the usual physical hazards from working on a boat and visiting markets. No
environmental impacts are expected from the implementation of Alternative 2.
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
The timeframe for the remedial action objectives to be achieved is projected to be 30 to 60 years
for this alternative. Monitoring of sediment, fish and ocean water would verify the predictive
ability of the natural recovery model and time period necessary to achieve RAOs.
6.4.2.6 Implementability
Alternative 2 is implementable. This section briefly describes the technical feasibility,
administrative feasibility, and the availability of services and materials.
Technical Feasibility
The institutional controls in this alternative do not involve technology, other than monitoring
and sampling equipment, which are proven and reliable. Thus, technical feasibility is high for
this institutional controls/monitored natural recovery alternative.
Administrative Feasibility
This alternative requires a high degree of coordination among numerous agencies to conduct
education, enforcement, and monitoring activities. For example, OEHHA will contribute
technical expertise for the updated advisory based on results from the ocean fish monitoring
program, as well as serve on the Technical Review Board for the public outreach and education
component of the institutional controls program. The enforcement component of the
institutional controls would be carried out through the CDFG. State and local health agencies,
such as the California Department of Health Services (DHS), Environmental Health
Investigations Branch, DHS~Food and Drug Branch, Los Angeles County Department of Health
Services (LACDHS), and Orange County Health Care Agency—Environmental Health Division
(OCHCA-EHD) would assist with outreach and provide inspection resources to support the
market monitoring program. Additionally, OCHCA-EHD may assist with delivery of public
outreach and education materials to target populations. While the MNR program would be run
by EPA, coordination with other agencies and organizations that monitor PV Shelf, e.g., Natural
Resource Trustees, LACSD, would occur.
Availability of Services and Materials
Services and materials to implement the ICs program and the MNR program are readily
available. To the extent that the ICs program relies on state and local agencies and nonprofit
organizations, cooperative agreements and other mechanisms are necessary to assure personnel
and materials are available. Fish monitoring would require trained personnel and materials for
sample collection and data analyses, as well as laboratory testing and reporting results of fish
tissue contaminant analyses. The personnel and materials for these activities are readily
available. Conducting public outreach and education would also require personnel and
materials that are readily available.
6.4.2.7 Cost
The estimated cost for Alternative 2 is just $15,500,000 over 10 years. This estimate includes 1C
costs for market monitoring, pier monitoring, ocean monitoring, community outreach, angler
outreach and enforcement, and MNR costs for sediment, water and fish sampling. The
estimated costs are based, in part, on the current institutional controls program. The costs for
the ICs program are approximately $1,900,000 a year. The MNR cost for Year 1 baseline
monitoring is $1,750,000. Sampling and analysis of COCs in sediment, fish and water would
occur at Years 5 and 10. Preparation of the Five-Year Reviews would include collection of field
data for the ICs and MNR programs.
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
A discount rate of seven percent is applied as stated in the preamble to the NCP, 55 FR 8722,
and the Office of Solid Waste and Emergency Response (OSWER) Directive 9355.3-20 entitled
"Revisions to OMB Circular A-94 on Guidelines and Discount Rates for Benefit-Cost Analysis"
(EPA, 2000). Attachment 1 provides details of the cost estimate for Alternative 2. Appendix D
provides details of the ICs program.
6.4.3 Alternative 3 - Small Cap with Monitored Natural Recovery and Institutional
Controls
Alternative 3 consists of the institutional controls and monitored natural recovery programs
described in Alternative 2 combined with placement of clean sediment to accelerate natural
recovery. Median PCB concentrations in surface sediment are 200 |o,g/kg. Median DDT
concentrations in surface sediment are 2000 Mg/kg (CH2M Hill, 2007). Sediment transport
modeling predicts DDT concentrations in sediment will fall below 1 mg/kg in approximately 20
years, except for the outfall area, where concentrations may increase (Sherwood, 2002). Median
DDT concentrations are estimated to reach 200 Mg/kg by 2053 (Appendix B).
Alternative 3 would cover the area near the outfall that has the highest surface concentrations of
COCs, approximately 320 acres, with clean material. This would reduce median DDT surface
concentrations across the Shelf to approximately 47 mg/kg OC and 5 mg/kg OC PCBs. The
clean cover would reduce contaminant flux from EA sediment and armor the outfall area from
potentially erosive storms. Subsection 5.2.3 provides a detailed description of Alternative 3.
Threshold Criteria
6.4.3.1 Overall Protection of Human Health and the Environment
Fish caught in the PV Shelf area contain concentrations of DDT and PCBs that exceed EPA
acceptable risk levels for human health. By addressing the source of contaminants, i.e., the
sediment, this alternative would accelerate natural recovery of the site.
Alternative 3 would apply a clean cover over the contaminated sediment in the outfall area to
physically isolate and immobilize COCs where they are highest. This would reduce the median
concentration of DDT in the surface sediment to approximately 47 mg/kg OC and the median
concentration of PCBs in the surface sediment to approximately 5 mg/kg OC. The lower PCB
sediment concentration would allow white croaker to reach the interim goal of 70 |o,g/kg PCBs
in white croaker fish tissue within 10 years, as white croaker loose their existing body burden of
PCBs. Under this alternative, median DDE concentrations in sediment across the shelf are
projected to drop to 230 Mg/kg in thirty years. This sediment level is correlated with the 400
DDT in fish.
Until fish tissue concentrations meet remediation goals, the institutional controls would
continue to protect consumers and reduce the likelihood that white croaker turn up in retail fish
markets. Outreach programs to keep consumers informed of which fish are safer to eat and
which cooking methods reduce contaminant content would continue. Bioaccumulation in
ecological receptors would continue until contaminant concentrations in fish drop to target
concentrations. The monitoring program would track reductions in contaminant
concentrations.
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
6.4.3.2 Compliance with Applicable or Relevant and Appropriate Requirements
Waters overlying the shelf contain concentrations of DDTs and PCBs that exceed the EPA
ambient water quality criteria (AWQC) for human health, 0.22 ng/L DDT and 0.064 ng/L PCBs
(Zeng et al., 1999). DDT concentrations in water exceed the AWQC for ecological health of 1
ng/L.
The water quality goal for DDT would be met 14 years sooner under Alternative 3 than under
natural recovery. An estimate of when PCB water criteria will be achieved will be calculated
once more recent data on PCBs in water are analyzed. PCB samplers were deployed along the
shelf during Winter 2007-2008 and recovered in April 2008; the data analysis has not been
completed.
Because Alternative 3 involves placement of a sand/sediment layer, action-specific ARARs that
would apply to this alternative include:
• The Marine Protection, Research, and Sanctuaries Act of 1972, commonly called the Ocean
Dumping Act, 33 U.S.C. Section 1404 et seq.
• Federal ocean dumping regulations, 40 CFR Part 220 et seq.
• Section 403 of the Clean Water Act
• Section 404 of the Clean Water Act
• Section 307(c)(l) of the Coastal Zone Management Act
Theses ARARs are discussed in more detail in Section 3.0.
Balancing Criteria
6.4.3.3 Long-Term Effectiveness and Permanence
As discussed in Section 1.0, most of the time near-bottom currents are too weak to move fine
sand. A cover of mixed sand, as is found in the potential borrow areas, would provide a long-
term protective layer. Periodic storms would mobilize the finer grained material; however,
studies of oceanographic conditions on the Shelf indicate the remaining coarser sand would
compact and form a stable layer (Sherwood et al., 2006, Ferre and Sherwood, 2008). The
proposed thickness of the cover (45 cm) will contain the EA sediment even if some of the cover
material is lost. Monitoring of cap integrity from erosion or bioturbation from large burrowing
infauna organisms, such as ghost shrimp, would be required. Data collected over the last
twenty years indicate the buried EA sediment has undergone little disturbance north of the
outfalls. Data collected during Winter 2007-2008 will provide additional information on near-
bed current velocities to assist in designing a cover that will contribute clean sediment to the
surrounding area but retain enough coarse material to prevent erosion of the cover.
6.4.3.4 Reduction of Toxicity, Mobility, or Volume through Treatment
There would be no reduction of toxicity, mobility, or volume through treatment with this
alternative, because no treatment would be implemented. Some reduction in toxicity, mobility,
and volume would occur through physical isolation of the most contaminated sediment and
natural recovery processes that are ongoing at the site.
6.4.3.5 Short-Term Effectiveness
Minimal short-term risks would occur as a result of implementing Alternative 3. Some
resuspension of sediment is inevitable during material placement. Depending on the degree of
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
resuspension, a short-term increase in bioavailability of COCs may be experienced. However,
the temporary increase in COCs would be offset by the reduction in contaminant concentrations
in surface sediment. Natural recovery processes would be expected to accelerate after
completion of the cover and the current risk from consuming contaminated fish would be
expected to decline.
Sediment placement by low-impact techniques would present a risk to workers due to the usual
physical hazards from working on a hopper dredge and operating heavy equipment. The ICs
and other MNR components of the alternative pose minimal risk to workers. CDFG wardens
would face the usual risks inherent in performing such tasks as boat patrols of fishing areas and
enforcement of fishing restrictions.
6.4.3.6 Implementability
Alternative 3 is implementable. This section briefly describes the technical feasibility,
administrative feasibility, and the availability of services and materials.
Technical Feasibility
Treatability studies to determine the most effective and lowest impact placement techniques
would be carried out as part of the remedial design. EPA would use low-impact techniques and
overlapping placement to minimize disturbance of the EA sediment.
Cap placement using a submerged discharge technique, such as a tailpipe/tremie tube with a
diffuser, will be much slower and more costly than the spreading method with a split hull barge
or hopper dredge. The placement technique is expected to have less impact on the effluent-
affected sediment. Scouring and resuspension are expected to be less when compared with the
bottom dump barge or hopper placement technique. Difficulties associated with submerged
discharge include the need for a high degree of control and proper positioning. For example,
because a tremie tube is a large-diameter straight vertical pipe, there is little reduction in
momentum or impact energy. The fallpipe/tremie tube would need a diffuser to disperse the
impact energy. Alternative 4 also discusses issues associated with placement implementability
and effectiveness.
The rest of this alternative does not involve technology, other than monitoring and sampling
equipment, which are proven and reliable.
Administrative Feasibility
Coordination with other state and federal agencies, including the California Coastal
Commission, Regional Water Quality Control Board, U.S. Fish and Wildlife Service, and
California Department of Fish and Game, would be required.
Sand placement would require preparation of plans and specifications, environmental
documentation and, for off-site activities, permit applications. Specific requirements would
vary depending on the source of the materials and potential magnitude of environmental
impacts associated with dredging at a borrow site. This documentation is a normal requirement
of most dredging projects; thus, administrative requirements should not interfere with
implementation of this alternative.
Availability of Services and Materials
The availability of services and materials are potential limitations for Alternative 3. However,
sand/sediment sources are available, as listed in Table 5-1. Dredging and placement equipment
are proven, although not at this depth, and are available.
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
6.4.3.7 Cost
Alternative 3 would place a sand/sediment layer over Grid Cell 8Q an area of 1.3 km2. The
volume of material needed is 864,000 yd3, which includes a 10 percent margin to account for
material that may be lost during placement. The cost for covering Grid Cell 8C would be
approximately $25 million plus another $6 million for treatability studies to assess low-impact
techniques and placement sequence. Construction monitoring and O&M would bring the cost
to $33.5 million. With institutional controls and monitored natural recovery, the alternative
would cost about $49 million over 10 years. The estimated cost includes the institutional
controls and monitoring programs described in Subsection 5.3.2.7. Attachment 1 provides
details of the cost estimate for Alternative 3.
6.4.4 Alternative 4 - Containment with Monitored Natural Recovery and Institutional
Controls
Alternative 4 combines the institutional controls and the monitoring of natural recovery
processes of Alternative 2 with containment, which consists of placing 45 cm of cap material
over the effluent-affected sediment deposit with the highest contaminant concentrations. The
cap area was selected because it represents the area of highest contaminant concentrations in
surface sediment and within the deposit. Non-capped areas would under go natural recovery.
The effectiveness of the remedy would be evaluated at the first five-year review. Post remedy
implementation data plus data from the additional studies would be used to develop a final
remedy for the site. Natural recovery processes would be evaluated for the five-year review to
verify that remediation goals are on track. Institutional controls would continue as well. A
more detailed description of Alternative 4 is provided in Subsection 5.2.4.
Threshold Criteria
6.4.4.1 Overall Protection of Human Health and the Environment
Alternative 4 would apply a clean cover over EA sediment to physically isolate and immobilize
COCs where they are highest. This would reduce the median surface concentration of DDT on
the shelf to 36 mg/kg OC and of PCBs to 3 mg/kg OC. The timeframe required to meet RAOs
for human health would be 18 years sooner than under natural recovery. Median DDE
concentrations in sediment associated with 400 |o,g/kg DDT in fish are estimated to be reach 22
years sooner than under no action. Median PCB concentrations in sediment would be below
the target sediment concentration of 7 mg/kg OC.
Until fish tissue concentrations meet remediation goals, the institutional controls would
continue to protect consumers and reduce the likelihood that white croaker turn up in retail fish
markets. Outreach programs to keep consumers informed of which fish are safer to eat and
which cooking methods reduce contaminant content would continue. Bioaccumulation in
ecological receptors would continue until contaminant concentrations in fish drop to target
concentrations. The monitoring program would track reductions in contaminant
concentrations.
6.4.4.2 Compliance with Applicable or Relevant and Appropriate Requirements
Waters overlying the shelf contain concentrations of DDTs and PCBs that exceed the EPA
ambient water quality criteria (AWQC) for human health, 0.22 ng/L DDT and 0.064 ng/L PCBs
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
(Zeng et al., 1999). DDT concentrations in water exceed the AWQC for ecological health of 1
ng/L.
Under Alternative 4, which caps the area around the outfalls and to the north over grid cells 8C,
7C and 6C, PV Shelf waters are expected to meet AWQC 18 years sooner than if no action is
taken. However, as discussed in Section 4.0, the placement of a cap would cause some sediment
resuspension, which could result in short-term increase in COCs in water. An estimate of when
PCB water criteria will be achieved will be calculated once more recent data on PCBs in water
are analyzed.
Because Alternative 4 involves placement of cap material, action-specific ARARs that would
apply to this alternative would include:
• The Marine Protection, Research, and Sanctuaries Act of 1972, commonly called the Ocean
Dumping Act, 33 U.S.C. Section 1404 et seq.
• Federal ocean dumping regulations, 40 CFR Part 220 et seq.
• Section 403 of the Clean Water Act
• Section 404 of the Clean Water Act
• Section 307(c)(l) of the Coastal Zone Management Act
Theses ARARs are discussed in more detail in Section 3.0.
Balancing Criteria
6.4.4.3 Long-Term Effectiveness and Permanence
The long-term effectiveness and permanence of Alternative 4 would be determined by the
physical stability of a cap, as measured by its resistance to erosion and seismic events; the depth
of significant bioturbation; and the potential for construction with minimal resuspension of EA
sediment. These factors are each discussed in more detail below. Long-term effectiveness and
permanence of Alternative 4 will also be determined by the monitored natural recovery and
institutional controls elements of this alternative, as described in Alternative 2.
Physical Stability of the Cap
Erosion resistant cap material must be able to withstand the shear stresses created by waves and
currents at the site. As discussed in Section 1.0, waves and currents over the deposit are less
energetic than inshore. The cap would be designed to withstand typical shear stresses that are
produced by currents and normal wave action, but should also be thick enough to weather
storm-induced stresses without compromising cap impermeability. Bottom boundary shear
stresses are the subject of ongoing research by the USGS, but initial estimates are that the shear
stress is less than 0.5 Pa (Cacchione, 2007). These initial estimates do not include the possible
bed stresses caused by internal tides/bores and solitons (Cacchione, 2007).
USAGE estimated the critical shear stress for design purposes to be 5 dynes/cm2 or 0.5 Pa
(Palermo et al., 1999). Erosion was modeled using the computer program Long-Term Fate
(LTFATE), which is a site-analysis program that uses coupled hydrodynamic sediment
transport and bathymetry change sub-models to compute site stability over time as a function of
local waves, currents, bathymetry, and sediment characteristics. Palermo et al. (1999) concluded
a minimum grain size of 0.1 mm or 0.3 mm (described as a fine sand) is sufficient to withstand
bottom boundary shear stresses at the PV Shelf Study Area at depths greater than 40 m. Using
0.5 Pa for a noncohesive sediment, calculations indicate an approximate 0.1 cm median grain
size is sufficient for erosion protection. Modeling and laboratory tests would be performed on
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
cap source material to determine critical shear stress of the designed cap. Resistance to erosion
will be a critical design factor
Sedflume analysis was performed at eight locations at the PV Shelf Study Area during the
March 2002 pilot cap survey (Gailani et al., 2004). Test results indicated that cap material only
eroded at shear stresses from 0.25 to 1.0 Pa. Cap material at the surface that was mixed with
effluent-affected sediment eroded at shear stresses from 0.25 to 4.0 Pa. Material below the
surface that consisted of cap material mixed with effluent-affected sediment as well as effluent-
affected sediment below the cap was most resistant to erosion. This material generally required
shear stress of 1.0 to 6.0 Pa to induce measurable erosion rates (Gailani et al., 2004).
Seismic stability of the cap also would be considered in the design and construction of an in situ
cap. The seismic stability of the PV Shelf was evaluated during the pilot capping study.
Palermo et al. (1999) demonstrated that liquefaction of cap materials and underlying sediments
may occur during seismic events of magnitude 5.5 or greater, but lateral deformation in areas of
slope less than 5 degrees would be not be expected to exceed three feet. Based on this
evaluation, areas of the PV Shelf with bottom slopes less than 5 degrees would be suitable for
capping from the standpoint of seismic stability, whereas a cap placed on the adjacent slope
would be susceptible to failure. Consequently, only areas of the shelf shallower than about 70
m (i.e., slopes less than 5 degrees) would be considered suitable for capping.
Bioturbation Depth
Biological mixing (bioturbation) processes are important both to the physical integrity of a cap
and the net movement of contaminants present in buried sediment. Protection from biodiffusion
can be accomplished through the construction of a cap with sufficient thickness to limit
recolonization into the effluent-affected sediment beneath the cap. The thickness of the sediment
layer affected by bioturbation can vary depending on the types and abundances of organisms
present and the characteristics of the substrate. The mean depth of the mixed layer from
worldwide estimates in marine sediments utilizing radionuclide techniques is about 10 cm
(Boudreau, 1994). Estimates of mixed layer depth for PV Shelf sediment vary, but appear to be
on the order of 5 to 8 cm (see Wheatcroft and Martin 1994; Santschi et al., 2001; SAIC, 2005b).
Biological activity below the surface mixed layer declines rapidly. In this transition layer,
organisms are much less abundant due to reduced availability of labile organic matter for food
and from demands placed on organisms (tube building, irrigation) resulting from the hypoxic
or anoxic state of surrounding interstitial water, requiring animals to maintain connection with
the surface. In 2004, SAIC (2005b) sampled the infauna from 64 cores (0.06 m2 surface area) and
recorded the presence of organisms within three vertical core segments: 0 to 15 cm, 15 to 30 cm,
and > 30 cm below the sediment water interface. Most of the cores (83 percent) penetrated
beyond 30-cm depth, while 29 (45 percent) penetrated deeper than 40 cm. Retained animals
were sieved through a 2-mm screen, identified to species, counted, and weighed. A total
surface area of 3.42 m2 was sampled from 19 stations, which included replicates. The upper
segment had the highest abundance, but the 15- to 30-cm abundance was relatively high at 62
percent of the surface density. Below 30 cm, densities dropped to 5 percent of surface levels.
Mid-core biomass was nearly as high as the surface (92 percent), declining to 30 percent below
30 cm. Average weight of individual organisms was greatest in the deep core section, where
individual organisms were 4 to 7 times as large as organisms from mid- and upper strata.
Based on these considerations, a cap thickness of 30 cm, equal to the combined depths of the
completely mixed zone and the enhanced biodiffusion zone, was considered adequate for
providing complete physical, as well as biological, isolation of the contaminated sediments. A
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
15-cm layer was added to accommodate operational variation in constructing a cap of uniform
thickness.
The actual long-term effectiveness of Alternative 4 will be determined by changes in fish tissue
contaminant concentrations measured during the MNR monitoring events. Although capping
will reduce surface sediment concentrations to levels associated with fish remediation goals,
average fish tissue concentration will not change immediately. Fish tissue reductions in
contaminants will occur as fish mature and grow (dilution of concentrations, internally) and
from the steady replacement of older, contaminated fish (pre-capping adults) with new fish
raised on the capped environment.
6.4.4.4 Reduction of Toxicity, Mobility, or Volume through Treatment
There would be no reduction of toxicity, mobility, or volume through treatment with this
alternative, because no treatment would be implemented. Physical isolation of COCs in
sediment would reduce their exposure and mobility. Some permanent reduction in toxicity,
mobility, or volume would occur through natural recovery processes at the site over time.
6.4.4.5 Short-Term Effectiveness
The primary considerations for the short-term effectiveness of Alternative 4 are resuspension of
effluent-affected sediments and the burial of benthic organisms due to cap placement. Short-
term effectiveness for the institutional controls and MNR component are discussed under
Alternative 2.
Sediment Resuspension
Cap construction will cause resuspension of contaminated surface sediment due to turbulence
associated with placement of the cap material. Resuspension of contaminated sediment would
temporarily promote desorption of DDTs and PCBs to waters overlying the PV Shelf Study
Area. Short-term adverse effects of this nature can be reduced by using low-energy
construction methods; however, resuspension can not be avoided. Resuspension and scouring
of contaminated sediment were observed during the pilot capping project (Fredette et al., 2002,
SAIC 2002).
The degree to which capping will cause resuspension of bottom sediment will depend on the
force with which the capping material impacts the bottom as well as the depth of previously
placed cap material. Use of a submerged diffuser technique to place the cap material closer to
the sediment bed is designed to reduce the force of impact. Fredette et al. (2002) determined
that using a spreading method allowed for controlled placement and less resuspension
compared with point placement. However, as observed during capping, the spreading
technique generated vertical plumes up to 30 feet high, comparable to those from point
placement, although they dissipated more quickly. Resuspension can be controlled through use
of accurate positioning information for the scows, barges, or hoppers distributing the material,
by facilitating overlapping placement techniques, and by controlling the rate of release from the
disposal equipment.
Minimizing short-term effects of resuspension appear to be possible using best management
construction practices and lessons learned from the pilot capping project.
Burial of Benthic Organisms
Covering existing shelf sediment with a cap of sand-sized materials would result in burial of a
large portion of the present benthic infaunal community. The subsequent recolonization of the
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
cap will typically occur in stages. The proposed sediment cap is expected to be populated within
days to weeks by adults and juvenile macrobenthic invertebrates that swim or migrate onto the
cap from the adjacent bottom, recruit from the plankton, or burrow upward to the new sediment
surface (burial of larger burrowers). Most of the existing benthos is likely to perish from burial,
as it is represented by a large component of nonmotile species. Emergent recolonization will be
most successful at cap thicknesses less than or equal to 10 cm, and thus will be most likely in the
thin flank deposits. Nonreproductive colonization (e.g., by organisms transported to the site or
burrowing through the deposit) can occur within a period of hours to days. Later successional
stage organisms are likely to appear within months and almost certainly within 2 to 5 years
following cap placement. Macrofaunal organisms comprising later successional stages typically
are larger and capable of burrowing to greater depths than earlier stage organisms. High rates
and densities of pioneering benthos may attract demersal predators to the site during the
productive stages of recolonization.
6.4.4.6 Implementability
Implementability of the institutional controls and monitored natural recovery elements of this
alternative are described in the evaluation of Alternative 2.
Containment requires identification of sand sources, verification of a placement method, and
monitoring to determine long-term effectiveness of the cap. This section briefly describes the
technical feasibility, administrative feasibility, and the availability of services and materials for
the capping component of the alternative.
Technical Feasibility
The technologies and services for this alternative, such as dredges and cap placement
equipment, are proven and reliable, although there are few precedents for capping at the depth
of the deposit. Challenges include finding suitable cap material, controlling resuspension and
residuals, developing low-impact placement techniques, and constructing a level, thick cap.
Cap Placement Technique
It is assumed that at least two cap placement techniques would be used: the spreading method
using a split hull material barge or hopper dredge, and low-impact methods, represented by
submerged diffuser placement method. The spreading method was considered to cause less
disturbance to the effluent-affected sediment compared with the point placement method
(Fredette et al., 2002). The spreading method is a relatively rapid placement technique with a
relatively minor modification to conventional point placement methods. The spreading method
would be used for placement of cap material in locations away from the LACSD outfalls after
an initial layer is placed using a drag arm or tremie tube with diffuser. A "buffer" zone around
the outfalls would be designated to protect the outfalls from burial.
The results of the sediment displacement study (SAIC, 2005 a) indicated that the thickness of the
effluent-affected sediment layer displaced during capping can vary from a few cm, at sites
where cap placements overlapped, up to 15 to 40 cm, at sites where cap material was placed
directly on top of effluent-affected sediment. This conclusion was based on the relatively
uniform depths for the peak DDE concentrations prior to capping compared with peak
concentrations after capping.
Scour depths of the effluent-affected sediment must be considered during the design phase.
Results from the pilot capping project indicated scour was greatest during the initial placement
events using point placement technique. Data also indicated scour was greatest directly below
6-22
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
the point placement location (SAIQ 2005a). Scours appears to be less in the areas radiating out
from the point placement location and also less using the overlapping point placement
technique. Limited data indicate the spreading placement technique caused less scour than the
point placement technique (SAIQ 2002). Low-impact techniques and overlapping placement to
place cap material on top of cap material would be used to minimize scour where possible.
Additionally, the extra thickness of the cap will make up for any loss of surface EA sediment
from scouring.
Administrative Feasibility
Coordination of capping activities with other state and federal agencies, including the
California Coastal Commission, Regional Water Quality Control Board, U.S. Fish and Wildlife
Service, and California Department of Fish and Game, would be required.
Cap construction would require preparation of plans and specifications, environmental
documentation, and for off-site activities, permit applications. Specific requirements would
vary depending on the source of the capping materials and potential magnitude of
environmental impacts associated with dredging at a borrow site. This documentation is a
normal requirement of most dredging projects; thus, administrative feasibility is not expected to
be difficult.
6.4.4.7 Cost
Alternative 4 includes costs for maintaining an institutional control program and monitored
natural recovery activities.
Cost estimates were developed for both low-impact placement and spreading placement
methods. Low-impact placement techniques, i.e., submerged drag-arm, tremie tube with
diffuser, are expected to be within the cost range of clamshell placement. During design and
procurement, other construction methods may be evaluated.
The estimate for containment includes cost of cap material, dredging, cap placement using a
low-impact technique or a bottom dump barge (spreading placement), and cap monitoring. A
unit cost was developed based on 1,000,000 yd3 of cap material, including dredging, and
placement of the material using either a clamshell barge or a bottom dump barge. The unit cost
for low-impact placement is approximately $44/yd3 and the unit cost for spreading placement
is approximately $21/yd3. The cap would be constructed using multiple techniques. About a
third of the cap material, for the initial cover and the area around the outfall, would be placed
using the more expensive low-impact method; the rest would be placed through spreading.
Alternative 4 would cap Grid Cells 6C, 7C, and 8C, an area of 2.74 km2. The cap volume, plus
10 percent, is 1,776,000 yd3.
The cost for capping Grid Cells 6C, 7C, and 8C would be approximately $57.1 million, which
includes $6 million for treatability studies. Construction monitoring would bring the cost to
$60.4 million. The estimated cost for a Five-Year Review would total $756,000. With
institutional controls and monitored natural recovery this alternative would cost about $76.7
million. Attachment 1 provides details of the cost estimates for Alternative 4.
6.5 Comparative Analysis of Alternatives
This section presents a comparative analysis of alternatives, in which the relative performance
of each alternative is evaluated for each of the seven evaluation criteria. The purpose of the
MAY09PVSHELFCHAPT6 6-23
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
comparative analysis is to identify the advantages and disadvantages of each alternative
relative to one another to identify key tradeoffs that need to be balanced. Table 6-8 summarizes
the comparison of each alternative to CERCLA criteria.
Threshold Criteria
6.5.1 Overall Protection of Human Health and the Environment
Alternative \, the no action alternative, takes no measures to protect human health and the
ecosystem of the PV Shelf Study Area. The overall protection of human health and the
environment of Alternative 2 is better than the no action alternative because the institutional
controls would effectively reduce risk to human health by educating consumers about
contaminated fish and by enforcing fishing restrictions. However, institutional controls do not
reduce risk to ecological receptors. Alternative 2 relies on natural processes to reduce risk over
time to ecological receptors. Evidence of contaminant loss and transformation has been
documented (Sherwood et al., 2006, Eganhouse and Pontolillo, 2007) as well as reductions in
fish contaminant concentrations (CH2M Hill, 2007). Predictive modeling (Appendix B)
estimates median concentrations in sediment will drop to levels correlated to the interim goal
for DDT in fish (400 Mg/kg) in 45 years. However, sediment in the outfall area would continue
to have DDT concentrations over 500 mg/kg OC for the foreseeable future or until the deposit is
eroded (Sherwood, 2002).
Alternative 3 places a sand cover in the outfall area on the southeast edge of the deposit that is
susceptible to erosion and is the area of highest surface and subsurface contamination. Under
Alternative 3, mean sediment concentrations on the Shelf would drop to 1,200 Mg/kg DDT and
150 Mg/kg PCBs; median carbon normalized values would be 47 mg/kg OC DDT and 5 mg/kg
OC PCBs. The DDT concentration is twice the remediation goal of 23 mg/kg OC; the PCB value
is less than the PCB remediation goal of 7 mg/kg OC. Sediment concentration (230 Mg/kg dw)
associated with fish tissue goal (400 Mg/kg) would be reached about 14 years sooner than under
natural recovery. Under Alternative 4, a cap covers twice the area of Alternative 3. Alternative
4 would reduce average sediment concentrations on the Shelf to 885 Mg/kg DDT and 110 Mg/kg
PCBs; median carbon normalized values would be 36 mg/kg OC DDT and 3 mg/kg OC PCBs.
Sediment DDT concentration would reach 230 Mg/kg eight years sooner under Alternative 4
than under Alternative 3. The PV Shelf slope has areas of high COC concentrations in sediment
that cannot be actively remediated because of the slope. How much this sediment contributes
to fish contamination will be the focus of a white croaker fish tracking study under alternatives
2, 3 and 4. Alternatives 3 and 4 would retain the institutional controls program and monitoring
program of Alternative 2.
6.5.2 Compliance with Applicable or Relevant and Appropriate Requirements
Waters overlying the shelf contain concentrations of DDTs and PCBs that exceed the EPA
ambient water quality criteria (AWQC) for human health, 0.22 ng/L DDT and 0.064 ng/L PCBs
(Zeng et al., 1999). Contaminant concentrations in water meet the PCB AWQC for ecological
health, i.e., of 30 ng/L, but not the DDT AWQC for ecological health of 1 ng/L.
Appendix B presents the assumptions and calculations used to project AWQC achievement.
Because of the lack of data on COCs in water, these estimates are highly speculative. The data
are useful in quantifying relative ranking of each alternative more than in predicting an exact
timeframe to reach AWQC goals. Data collected during Winter 2007-2008 will be used to verify
6-24
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
or amend the timeframe. Under Alternative 2, human health AWQC are projected to be met in
30 to 60 years. Under Alternative 3, AWQC are projected to be met 14 years sooner than under
Alternative 2. Alternative 4, which caps the area around the outfalls and to the north over grid
cells 6C and 7C, PV Shelf waters are expected to meet AWQC 18 years sooner than if no action
is taken. An estimate of when PCB water criteria will be achieved will be calculated once more
recent data on PCBs in water are analyzed.
Placement of capping material under either Alternative 3 or 4 would require compliance with
the substantive requirements in Section 404 of the Clean Water Act, the Ocean Dumping Act,
33 U.S.C. Section 1404 et seq., federal ocean dumping regulations at 40 CFR Part 220 et seq.
Dredged material must meet substantive federal testing guidelines before it can be approved for
disposal; see 40 CFR Part 227.
6.5.3 Long-Term Effectiveness and Permanence
The PV Shelf is undergoing natural recovery and over time the surface layer of EA sediment
would be diluted or dispersed. However, in the interim, contaminants would continue to
bioaccumulate in fish and other organisms. The long-term effectiveness and permanence of
Alternative 1 is low because DDTs and PCBs in sediment would continue to pose a risk to
human health and the environment without any measures being taken to reduce human
exposure. All of the other alternatives use the institutional controls program to reduce risk
through education, enforcement, and monitoring. Alternative 3 would accelerate natural
recovery by applying a nonengineered cap to the southeast edge of the deposit where the
contaminant concentrations are greatest. Alternative 4 would construct a cap over the thickest
part of the deposit. All of the alternatives achieve comparable long-term protectiveness, they
vary according to the time involved. Alternative 2 would require 30 to 45 years to reach
remediation goals in water and sediment. A factor that could influence recovery time under
Alternative 2 is the contaminant contribution from the outfall area. Although this is a small
area, about 1.6 percent of the site, it's estimated to contain 44 percent of the shelf's DDT and 13
percent of the PCBs. Field studies to quantify contaminant flux and sediment transport from
this area are necessary to more accurately predict recovery rates under any alternative.
Alternative 3 places a 30- to 45-cm cover over the area of greatest contamination. Although the
area has weaker currents than those measured at either end of the Shelf (Noble, et al. 2008), the
characteristics of the sediment make it more susceptible to erosion (Ferre and Sherwood, 2008).
These data indicate a 45-cm thick cover would provide long-term protection. Alternative 4 caps
the high concentrations of DDTs and PCBs in the outfall area and to the north where analysis of
currents and sediment properties indicate erosion may occur (Ferre and Sherwood, 2008),
although existing measurements show the area is still net depositional (Figure 2-11). Erosion,
seismic events, bioturbation, and recontamination are the primary processes that have a
potential to impact the long-term effectiveness and permanence of a cap (Palermo et al., 1999).
As stated in Subsection 5.2.4.3, the cap thickness is considered adequate to provide complete
physical as well as biological isolation of the contaminated sediments. Long-term monitoring
(O&M) would be necessary to check cap integrity and perform any repairs to the cap if breaches
are found. The alternative would provide long-term effectiveness.
6.5.4 Reduction of Toxicity, Mobility, or Volume through Treatment
None of the alternatives reduces the toxicity, mobility, or volume of contamination at the
PV Shelf Study Area through treatment. Some permanent reduction in toxicity, mobility, or
MAY09PVSHELFCHAPT6 6-25
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
volume (without treatment) would occur through natural recovery processes over a period of
time at the site. Capping would reduce mobility; however, this is not considered treatment.
6.5.5 Short-Term Effectiveness
Alternative 1 would not increase short-term risks to the community or to workers since no
action would occur under this alternative. Similarly, no environmental impact from
construction activities would occur.
Alternative 2 would pose little short-term risk to the community. Implementation of the
institutional controls and monitoring programs, including sampling fish, would present a slight
risk to workers due to the usual physical hazards from working on a boat and visiting markets.
No short-term environmental impacts are expected from the implementation of Alternative 2.
Compared to the other alternatives, Alternatives 3 and 4 pose a greater short-term risk to the
environment at the PV Shelf Study Area because they would resuspend effluent-affected
sediment and bury the benthic community. In-water work, including placement of cap materials
and dredging will cause resuspension of sediment. The suspended sediment is likely to be
transported outside the construction zone and settle in other areas. Resuspension of
contaminated sediment may adversely impact aquatic biota in and adjacent to the construction
zone. Water quality impacts resulting from in-water construction would be limited to short-term
increases in suspended sediment. Resuspension management would include using best
management practices (BMPs) during in-water work and engineering and in-water construction
methods designed to minimize resuspension (use of spreading and low-impact placement
techniques). Monitoring of turbidity, current speeds, surge impacts, etc. would be performed
during remedial action to determine effectiveness of resuspension management and modify
capping activities if warranted.
Another short-term impact from Alternatives 3 and 4 is that a cover or cap will bury a large
number of benthic organisms, although some larger-sized species would be capable of
burrowing up through deposited material. Most of the existing benthos is likely to perish from
burial, as they are represented by a large component of nonmotile species. Emergent
recolonization will be most successful at cap thicknesses less than or equal to 10 cm, and thus
will be most likely in the edges of the cap. In the thinner areas, it is likely that the cap would be
populated within weeks by adults and juvenile macrobenthic invertebrates that swim or
migrate onto the cap from the adjacent bottom, recruit from the plankton, or burrow upward to
the new sediment surface (burial of larger burrowers). Recolonization would take 2 to 5 years.
Alternatives 3 and 4 are not expected to pose a short-term risk to the community. There would
be an increase in ship or truck traffic, depending on cap material source. Alternative 4 would
require more material. The alternatives would pose some risk to workers from the usual
physical hazards of working on the water (e.g., dredging, cap placement).
6.5.6 Implementability
TGChnical Possibility. The no action alternative, Alternative 1, requires no additional effort and
would be readily implementable. Implementation of any of the others alternatives evaluated
present technical challenges, especially the placement of sand material in Alternatives 3 and 4.
However, all alternatives evaluated are considered technically implementable. Alternative 4
would be the most difficult alternative to implement.
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
The technical feasibility of the institutional controls program and monitored natural recovery
are high. The ICs program has been in place for many years and has a proven track record of
successful implementation. Monitoring activities on PV Shelf have been conducted by local and
federal agencies. The water depth poses challenges to collection of sediment cores; however,
suitable equipment is available and has been used successfully. Collection of fish, sediment,
and water are all technically feasible.
Technical feasibility for containment requires evaluation of source materials for the cap and the
placement method. The availability of sand for capping at PV Shelf Study Area is difficult to
predict because of the need of sand for beach replenishment or in-water and upland
construction. However, the volumes required, 864,000 yd3 for Alternative 3, and 1,776,000 yd3
for Alternative 4, is less than sediment volumes projected to be generated by maintenance
dredging (Table 5-3). It is likely that the most cost-effective source of cap material would be
from an on-site borrow area or from maintenance dredging of Southern California ports and
harbors. Material source(s) would be identified during the design phase.
Placement of subaqueous material under either Alternative 3 or 4 would be technically difficult
because of the fine grain and high moisture content of the effluent-affected sediment. Cap
material would need to be applied slowly and uniformly to reduce resuspension of
contaminated sediments. Placement techniques considered in this FS include the spreading
method using a split hull material barge or hopper dredge and low-impact placement methods
such as submerged drag-arm or tremie tube with diffuser. Low-impact techniques would be
used to place an initial cap layer of 10 to 15 cm, then the rest of the cap could be applied using
the spreading technique. The spreading method could be used to place most of the cap material
while more precise placement methods could be designated for areas nearer to the outfalls. A
buffer zone would be established around the outfall so that cap material would not interfere
with operation or maintenance activities.
Administrative Feasibility. The administrative feasibility of Alternative 1 is high because no
action is taken. Alternatives 2, 3 and 4 require a high degree of coordination among numerous
agencies to conduct education, enforcement, and monitoring activities for the institutional
controls program. However, the existing ICs program has been operating for several years, and
many of the administrative issues have been worked out. The plan for monitoring natural
recovery is administratively feasible as well. The site has been monitored and sampled for
many years, the administrative feasibility is high.
Cap construction would require preparation of plans and specifications and coordination with
other agencies. Placement of capping material under either Alternative 3 or 4 would require
compliance with the substantive requirements in Section 404 of the Clean Water Act, the Ocean
Dumping Act, 33 U.S.C. Section 1404 et seq., federal ocean dumping regulations at 40 CFR Part
220 et seq. Dredged material must meet substantive federal testing guidelines to be approvable
for disposal, 40 CFR Part 227. Specific requirements would vary depending on the source of the
capping materials.
6.5.7 Cost
A comparison of the costs for each alternative is provided in Table 6-7. As stated at the
beginning of this section, this feasibility study is for an interim action. A final remedy selection
will occur after the first five-year review. Alternative costs are projected out over a 10-year
period. The no action alternative would require no capital or operating costs and would be less
MAY09PVSHELFCHAPT6 6-27
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
expensive than current cost due to existing ICs program. Besides the no action alternative,
Alternative 2 is the least expensive with total costs estimated at $15.5 million over 10 years.
Alternative 3 is considerably more expensive, with total costs over 10 years of $49 million.
Alternative 4 would be the most expensive remedial alternative, at $76.7 million over 10 years.
Both alternatives budget $6 million for treatability studies as part of remedial design and post-
cap construction monitoring.
Table 6-7: Comparison of Remedial Alternative Costs (10-Year Implementation Horizon)
Alternatives
Alternative 1 - No Action
Alternative 2 - Institutional Controls (ICs)
and Monitored Natural Recovery (MNR)
Alternative 3 -Enhanced Monitored
Natural Recovery and Institutional Controls
Alternative 4 - Containment with MNR and
Institutional Controls
Capital Costs
Non-Discounted Cost
$0
$3,650,000
$36,600,000
$64,100,000
Periodic Costs
Net Present Value Cost
$0
$11,850,000
$12,400,000
$12,600,000
Total Costs
$0
$15,500,000
$49,000,000
$76,700,000
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
Table 6-8:
Evaluation of Alternatives against CERCLA Criteria
CERCLA Criteria
Alt.l No Action
Alt. 2 Institutional
Controls & Monitored
Natural Recovery
Alt. 3 ICs, MNR &
Small Subaqueous in
situ Cap
Alt 4: ICs, MNR &
Subaqueous in situ
Cap
Threshold Criteria
Overall Effectiveness
Human Health Protection
RAO 1: reduce to acceptable levels the risks to
human health from ingestion of fish contaminated
with DDTs and PCBs
Achieve interim goal of 400 |ig/kg DDT and
70 |ig/kg PCBs in white croaker and other
benthic-feeding fish
No reduction in risk.
DDT concentrations
will remain high
around outfalls but
drop in other areas.
Impact of high cone.
in outfall area
unclear.
Controls, but does not
eliminate, risk from
ingesting contaminated
fish. CoC in fish exceed
IxlO4 risk. CoCs on the
Shelf would drop over
time. Median DDT cone.
in surface sediment is
estimated to fall <1 ppm
by 2024 and reach target if
230|ig/kgby2053.
See Alt. 3 would apply a
sand cover to the area of
highest contaminant
cone, (approx. 1.3 km2),
to prevent erosion and
reduce COCs in
sediment. DDT cone, in
white croaker would
reach 400 jig/kg in 30
yrs. PCB cone, of 70
|ig/kg would be reached
in 10 years.
See Alt. 2. Cap would
cover approx. 2.74 km2
of the Shelf, including
the flat areas (not slope)
that exceed the PCB
cleanup goal. Median
concentrations of DDT
associated with 400
|ig/kg in white croaker
would be reached in 22
yrs. CoCs in fish would
drop thru depuration; it
could take 10 yrs (one
lifetime) for PCB cone.
in white croaker to drop
to 70 |ig/kg.
Environmental Protection
RAO 2: reduce to acceptable levels risks to PV
Shelf fish and benthic invertebrates
Support Natural Resource Trustees' strategies
to sustain wildlife recovery
Achievement of human health ARARs would also
provide protection for wildlife.
No reduction in risk
Does not provide
additional protection.
Median DDT cone.
forecasted to fall
<1000|ig/kgby2024,
and <200 jig/kgby 2053.
Isolates 1.3 km2 area w/
highest CoC concentra-
tion. Immediately
reduces mean cone, of
DDT to 1200 |ig/kg &
PCBs to 150 |ig/kg. DDT
projected to fall below
200 |ig/kg 14 yrs sooner
than under no action.
Isolates 2.74 km2 of
sediment with highest
CoC concentrations,
reducing mean cone, to
890 |ig/kg DDT & 110
|ig/kg PCBs. DDT
forecast to fall below
200 |ig/kg 22 yrs sooner
than under no action.
Compliance with ARARs
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
Table 6-8:
Evaluation of Alternatives against CERCLA Criteria
CERCLA Criteria
Alt.l No Action
Alt. 2 Institutional
Controls & Monitored
Natural Recovery
Alt. 3 ICs, MNR &
Small Subaqueous in
situ Cap
Alt 4: ICs, MNR &
Subaqueous in situ
Cap
Chemical-Specific ARARs
Environmental AWQC:
DDT 1 ng/L;
Human Health AWQC:
DDT 0.22 ng/L;
PCBs 0.064 ng/L
DDT levels in water
projected to meet HH
AWQC by 2037. Date
for PCBs to reach HH
AWQC being
determined. This alt.
has no monitoring to
confirm AWQC met.
DDT levels in water
projected to meet HH
AWQC by 2037. Alt.
includes monitoring. Date
for PCBs to reach HH
AWQC being determined.
DDT levels in water
projected to meet HH
AWQC by 2023. Alt.
includes monitoring.
Date for PCBs to reach
HH AWQC being
determined.
DDT levels in water
projected to meet HH
AWQC by 2019. Alt.
includes monitoring.
Date for PCBs to reach
HH AWQC being
determined.
Location-Specific ARARs
Action-Specific ARARs
Balancing Criteria
Long-Term Effectiveness
Magnitude of Residual Risk
Adequacy & Reliability of Controls
Existing risk will
drop over time, but
this alt. does not track
changes.
No controls over
remaining
contamination.
monitoring must comply
with CDFG Title 14 fish
protection regulations
Loss processes are
predicted to reduce risk
over 30-60 years.
ICs have limited
effectiveness.
Contaminated fish
limited, but not absent,
from markets.
capping must comply
with CZMA
See Alt. 1. capping must
comply with MRPSA &
CWA
Action predicted to
reduce risk over 15^0
years. Because waste is
only contained, hazard
remains until natural
processes degrade DDE.
Cover would prevent
exposure, but also
prevent CoC loss.
ICs have limited
effectiveness. Reliability
of a cap can be high.
Would need monitoring
& maintenance.
capping must comply
with CZMA
See Alt. 1. capping must
comply with MRPSA &
CWA
Action predicted to
reduce risk over 10-30
years. Because waste is
only contained,
inherent hazard
remains until natural
processes degrade DDE.
Cap would prevent
exposure and CoC loss.
ICs have limited
effectiveness. Reliability
of a cap can be high.
Would need monitoring
& maintenance.
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
Table 6-8:
Evaluation of Alternatives against CERCLA Criteria
CERCLA Criteria
Alt.l No Action
Alt. 2 Institutional
Controls & Monitored
Natural Recovery
Alt. 3 ICs, MNR &
Small Subaqueous in
situ Cap
Alt 4: ICs, MNR &
Subaqueous in situ
Cap
Need for 5-Yr Reviews
Yes.
Yes. Review would be
required to ensure
adequate protection of
human health and the
environment.
Reduction of Toxicity, Mobility, or Volume thru Treatment
Treatment Process None. None
Reduction of Toxicity, Mobility or Volume
Statutory Preference for Treatment
Short-Term Effectiveness
Community Protection
Worker Protection
Environmental Impacts
Time Until Action is Complete
Reduction in volume See Alt. 1
thru loss processes &
DDE transformation.
Toxicity of daughter
products unknown.
Does not satisfy.
Risk to community
increased since
existing ICs would
stop under this alt.
N/A
N/A
N/A
Does not satisfy.
Risk to community
managed through ICs.
N/A
N/A
RAOs predicted to be met
in 30-45 years under
Yes. DDTs & PCBs left in Yes. DDTs & PCBs left
sediment. DDTs in sediment. DDTa
degrading, but not PCBs. degrading, but not
PCBs.
None
See Alt. 1. Cap would
reduce mobility but is
not considered
treatment.
Does not satisfy.
Risk to community
managed thru ICs. May
cause short-term
increase in CoC
bioavailability from
resuspended sediment.
No significant risk from
monitoring activities.
Resuspension of EA
sediment; burial of
benthic organisms
RAOs predicted to be
met 14 years sooner thru
None.
See Alt. 1. Capping
would reduce mobility
but is not considered
treatment.
Does not satisfy.
Risk to community
managed thru ICs. May
cause short-term
increase in CoC
bioavailability from
capping resuspended
sediment.
No significant risk from
monitoring & capping.
Resuspension of EA
sediment; burial of
benthic organisms
RAOs predicted to be
met 18 to 22 years
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
Table 6-8:
Evaluation of Alternatives against CERCLA Criteria
CERCLA Criteria
Alt.l No Action
Alt. 2 Institutional
Controls & Monitored
Natural Recovery
Alt. 3 ICs, MNR &
Small Subaqueous in
situ Cap
Alt 4: ICs, MNR &
Subaqueous in situ
Cap
natural loss processes.
Implementability
Ability to Construct & Operate
Ease of Doing More Action if Needed
Ability to Monitor Effectiveness
No construction or
operation.
By pursuing an
interim ROD,
additional action
would be easy.
No monitoring.
Ability to Obtain Approvals & Coordinate with
Other Agencies
N/A
No construction. ICs
program in operation
since 2001. MNR program
easy to implement.
Interim ROD leaves door
open for further action at
time of final ROD.
ICs & MNR programs
monitor CoCs in
sediment, water, fish &
behavior changes from
outreach.
Successful ongoing
coordination with State,
federal & local agencies.
Availability of Equipment and Materials
N/A
No special equipment.
hot spot cover than thru
natural loss processes.
Placement difficult
because of location,
depth, & characteristics
of sediment. ICs & MNR
easy to implement.
Interim ROD leaves door
open for further action at
time of final ROD.
MNR would track CoCs
in water, sediment &
fish. Cover easy to
monitor.
See Alt. 2., anticipate no
difficulties coordinating
with other agencies for
monitoring. Need CA
Coastal Commission
approval & possibly
USAGE permit if marine
sediment is dredged for
cover material.
Cover material sources
available.
sooner thru capping
than thru natural loss
processes.
Capping difficult
because of location,
depth, & characteristics
of sediment. ICs, MNR
easy to implement.
Interim ROD leaves
door open for further
action at time of final
ROD.
Easy to monitor. MNR
would track COCs in
water, sediment & fish.
See Alt. 3. Need CA
Coastal Commission
approval & possibly
USAGE permit if
marine sediment is
dredged for cap
material. Coordination
with other agencies for
ICs and MNR.
Cap material sources
available.
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
Table 6-8: Evaluation of Alternatives against CERCLA Criteria
CERCLA Criteria Alt.l No Action Alt. 2 Institutional Alt. 3 ICs, MNR & Alt 4: ICs, MNR &
Controls & Monitored Small Subaqueous in Subaqueous in situ
Natural Recovery situ Cap Cap
Availability of Technologies N/A Monitoring equipment Technologies available; Capping technologies
and procedures well additional studies available; RD studies
established. needed to determine best needed to determine
methods. best methods.
MAY09CHAP6
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6.0 DETAILED ANALYSIS OF REMEDIAL ALTERNATIVES
MAY09CHAP6
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Attachment 1: Remedial Alternatives Cost Estimate May09
Att-1
Table 1: Institutional Controls Details
Description
Year 1 Costs
Institutional Controls Plan
Monitoring
Monitoring - Market
Plans
Sample Collection
Sample Materials
Shipping/Transport
Data Assessment
Analysis
Monitoring- Catch Ban Area
Plans
Mobilization/Demobilization
Boat Rental
Sampling Materials
Shipping/Transport
Data Assessment
Analysis
Monitoring — Pier
Plans
Sample Collection
Sampling Materials
Shipping/Transport
Data Assessment
Analysis
Outreach
Quantity
1
1
1
1
1
1
50
1
1
4
1
1
1
100
0
1
1
1
1
40
Unit Cost
$ 30,000
$ 14,000
6,600
1,000
1,000
22,000
720
$ 10,000
3,400
4,500
1,000
1,000
22.000
720
$ -
5,300
1,000
1,000
22,000
720
Unit
EA
LS
LS
LS
LS
LS
EA
LS
LS
LS
LS
LS
LS
EA
LS
LS
LS
LS
LS
EA
Total
$ 30,000
$ 14,000
6,600
1,000
1,000
22,000
$ 36,000
$ 10,000
3,400
18,000
1,000
1,000
22,000
72,000
$ -
5,300
1,000
1,000
22,000
28,800
Comment
Based on hours in 2001 EPA work plan
ESP, QAPP, HSP
Assumes 10 markets; based on hours in 2007 EPA work plan
Samples and equipment
Includes data management, and QA/QC oversight and data validation;
based on hours in 2007 EPA work plan
10 markets, 5 white croaker at each; sample preparation, lipid content,
DDT (6 isomers) and PCB congener analysis
ESP, HSP — same QAPP for market monitoring
Includes travel and per diem
Includes boat and labor for 4 days
Samples and equipment
Includes data management and QA/QC oversight and data validation;
based on hours in 2007 EPA work plan
5 catch ban area locations, 10 white croaker and 10 kelp bass each;
sample preparation, lipid content, DDT (6 isomers) and PCB congener
analysis
same as market monitoring plan
Assumes 4 piers
Samples and equipment
Includes data management, QA/QC oversight and data validation; based
on hours in 2007 EPA work plan
4 piers, 10 white croaker at each; sample preparation, lipid content, DDT
(6 isomers) and PCB congener analysis
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Attachment 1: Remedial Alternatives Cost Estimate May09
Att-2
Table 1: Institutional Controls Details
Description
Community Outreach
Angler Outreach
Enforcement
City & County Health Agencies
CA Dept. of Fish and Game
Catch Ban Patrol
Pier Patrols
Reporting
Subtotal A
Contingency (20% of Subtotal A)
Subtotal B
Project Mgmt (6% of Subtotal B)
Total Capital Costs for ICs
O&M Costs
Annual Costs for Years 2 — 5
Monitoring - Market
Analysis Monitoring - Market
Monitoring — Pier
Analysis Monitoring - Pier
Community Outreach
Enforcement
Subtotal A
Contingency (20% of Subtotal A)
Subtotal B
Project Mgmt (6% of Subtotal B)
Annual O&M Subtotal for Years
2-5
Total O&M NPV for Years 2 -5
Quantity
1
1
3
192
192
48
1
50
1
1
1
1
Unit Cost
$ 880,000
120,000
$ 60,000
$ 75
75
75
$ 30,000
720
$ 29,300
$ 720
$1,000,000
212,400
Unit
LS
LS
EA
HR
HR
HR
LS
EA
LS
EA
LS
LS
Total
$ 880,000
120,000
$ 180,000
$ 14,400
14,400
3,600
1,508,500
301,700
1,810,200
108,612
1,900,000
$30,000
36,000
$29,300
$ 28,800
$1,000,000
212,400
$1,336,500
267,300
1,603,800
96,228
$1,700,000
$5,400,000
Comment
Based on 2007 EPA work plan
Based on 2006 costs and 2007 EPA work plan
Training, tracking, and reporting for LA and OC market inspections;
based on 2007 estimate
Monthly patrol with 2 wardens; 8 hrs/patrol
Monthly patrol with 2 wardens' 8 hrs/patrol
Monthly reporting; 4 hrs/month
10% scope and 10% bid
From USAGE and EPA estimating Guide July 2000
Includes sample collection, data management, an QA/QC oversight and
data validation; based on hours in 2007 EPA work plan
10 markets, 5 white croaker at each; sample preparation, lipid content,
DDT (6 isomers) and PCB congener analysis.
Includes sample collection, materials, shipping/transportation, data
management and QA/QC oversight and data validation; based on hours
in 2007 EPA work plan
4 piers, 10 white croaker at each;; sample preparation, lipid content,
DDT (6 isomers) and PCB congener analysis
same as initial LOE
same as initial LOE
10% scope and 10% bid
From USACE and EPA Estimating Guide July 2000
annual cost
7% discount rate
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Attachment 1: Remedial Alternatives Cost Estimate May09
Att-3
Table 1: Institutional Controls Details
Description
Year 5 Only
Monitoring - Catch Ban Area
Analysis Monitoring — Catch
Ban Area
5-Yr Review Report
Subtotal A
Contingency (20% of Subtotal A)
Subtotal B
Project Mgmt (6% of Subtotal B)
Additional O&M for Year 5
Only
Total O&M NPV for Year 5
Only
Annual Costs for Years 6-10
Monitoring - Market
Analysis Monitoring - Market
Monitoring — Pier
Analysis Monitoring - Pier
Community Outreach
Enforcement
Subtotal A
Contingency (20% of Subtotal A)
Subtotal B
Project Mgmt (6% of Subtotal B)
Annual O&M Subtotal for Years
6-10
Total O&M NPV for Years 6-10
Quantity
1
100
1
1
50
1
40
1
1
Unit Cost
$ 31,900
$ 720
$ 36,000
$ 230,000
720
$ 29,300
$ 720
1,000,000
212,400
Unit
LS
EA
EA
LS
EA
LS
EA
LS
LS
Total
$ 31,900
72,000
36,000
139,900
27,890
167,880
10,073
177,953
$127,000
$30,000
36,000
$29,300
$ 28,800
1,000,000
212,400
$1,336,500
267,300
1,603,800
96,228
1,700,028
4,970,000
Comment
Year 5 only; includes mob/demob, boat rental, labor, materials,
shipping/ transport, data management, and QA/QC oversight and data
validation; based on hours in 2007 EPA work plan
Year 5 only; 5 catch ban locations, 10 white croaker and 10 kelp bass
each; sample preparation, lipid content, DDT (6 isomers) and PCB
congener analysis
Year 5 only
10% scope and 10% bid
From USACE and EPA Estimating Guide (July 2000)
annual cost
7% discount rate
Includes sample collection, data management, an QA/QC oversight and
data validation; based on hours in 2007 EPA work plan
10 markets, 5 white croaker at each; sample preparation, lipid content,
DDT (6 isomers) and PCB congener analysis.
Includes sample collection, materials, shipping/transportation, data
management and QA/QC oversight and data validation; based on hours
in 2007 EPA work plan
4 piers, 10 white croaker at each; sample preparation, lipid content, DDT
(6 isomers) and PCB congener analysis
same as initial LOE
same as initial LOE
10% scope and 10% bid
From USACE and EPA Estimating Guide (July 2000)
annual cost
7% discount rate
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Attachment 1: Remedial Alternatives Cost Estimate May09
Att-4
Table 1: Institutional Controls Details
Description
Year 10 Only
Monitoring - Catch Ban Area
Analysis Monitoring — Catch
Ban Area
5-Yr Review Report
Subtotal A
Contingency (20% of Subtotal A)
Subtotal B
Project Mgmt (6% of Subtotal B)
Additional O&M for Year 10
Only
Total O&M NPV for Year 10
Only
Total O&M NPV Cost
Total Cost
Quantity
1
100
1
Unit Cost
$ 31,900
$ 720
$ 36,000
Unit
LS
EA
EA
Total
$ 31,900
72,000
36,000
139,900
27,890
167,880
10,073
177,953
90,400
$10,600,000
$12,500,000
Comment
Year 10 only; includes mob/demob, boat rental, labor, materials,
shipping/ transport, data management, and QA/QC oversight and data
validation; based on hours in 2007 EPA work plan
Year 5 only; 5 catch ban locations, 10 white croaker and 10 kelp bass
each; sample preparation, lipid content, DDT (6 isomers) and PCB
congener analysis
Year 10 only
10% scope and 10% bid
From USACE and EPA estimating Guide July 2000
annual cost
7% discount rate
7% discount rate
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Attachment 1: Remedial Alternatives Cost Estimate May09
Att-5
Table 2: Monitored Natural Recovery Details
Description Quantity
Year 1 Costs
Natural Recovery Plan 1
Unit Cost
$ 30,000
Unit
EA
Total
$ 30,000
Comment
Based on hours in 2001 EPA work plan
Sediment and Water Sampling and Analysis
Plans (SAP, QAP, HSP)
Mobilization/Demobilization
Equipment Rental
Materials
Shipping/Transport
Data Assessment Report
Sediment Analysis
Sample Preparation
Water Content
Total organic content (TOC)
Grain Size
DDTs
PCBs
Pore Water Analysis
Sample Preparation
Hydrogen Sulfide
DDTs
PCBs
Water Column Analysis
Polyethylene Device (FED)
DDTs
PCBs
1
1
18
1
1
1
750
750
750
750
750
750
50
50
50
50
270
270
270
Sediment and Water Sampling Subtotal
Fish Sampling
Plans (SAP, QAP, HSP)
Mobilization/Demobilization
Equipment Rental
Materials
Shipping/Transport
Data Assessment Report
1
1
4
1
1
1
$ 50,000
14,000
6,300
7,000
4,000
200,000
244
5
35
75
226
245
$ 225
100
400
400
$5
400
400
14,000
3,400
4,500
1,200
1,000
36,000
LS
LS
DAY
LS
LS
LS
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
LS
LS
DAY
LS
LS
LS
$ 50,000
14,000
100,800
7,000
4,000
200,000
183,000
3,750
26,250
56,250
169,500
183,750
$ 11,250
5,000
20,000
20,000
1,350
$ 108,000
108,000
$1,271,900
$ 14,000
3,400
45,000
1,200
1,000
36,000
Includes boat and labor for 1 6 days
50 cores total; 30 stations, LACSD transects 1- thru 10-B, C, D; duplicate
cores at 60-m and 150-m stations; 4-cm increments; box core
includes 6 DDT isomers, DDMU, DDNU, DBF
specific congener list will be used
50 samples total, taken with sediment samples
includes 6 DDT isomers, DDMU, DDNU, DBF
specific congener list will be used
30 stations; , LACSD transects 1- thru 10-B, C, D; 9 passive samplers per
station: 3 m from bed, mid-column and 5 m below surface
includes 6 DDT isomers, DDMU, DDNU, DBF
specific congener list will be used
Includes boat and labor for 10 days
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Attachment 1: Remedial Alternatives Cost Estimate May09
Att-6
Table 2: Monitored Natural Recovery Details
Description Quantity
Demersal and Pelagic Fish
Sample preparation
Lipid content
DDTs
PCBs
Fish Sampling Subtotal
Baseline Monitoring
Subtotal A
Contingency (20% of Subtotal A)
Subtotal B
Project Mgmt (6% of Subtotal B)
Total Baseline Monitoring
O&M Costs
Year 5 Monitoring
Plans (SAP, QAP, HSP)
Mobilization/Demobilization
Equipment Rental
Materials
Shipping/Transport
Sediment Analysis
Sample Preparation
Water Content
Total organic content (TOC)
Grain Size
DDTs
PCBs
Pore Water Analysis
Sample Preparation
Hydrogen Sulfide
DDTs
PCBs
Water Column Analysis
Polyethylene Device (FED)
60
60
60
60
60
1
1
18
1
1
480
480
480
480
480
480
32
32
32
32
144
Unit Cost
244
25
226
245
$ 0
14,000
6,300
5,000
4,000
244
5
35
75
226
245
$ 225
100
400
400
$5
Unit
EA
EA
EA
EA
LS
LS
DAY
LS
LS
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
Total
14,640
1,500
13,560
14,700
$100,600
$1,372,500
274,500
$1,647,000
98,800
1,745,800
$1,745,800
0
14,000
63,000
5,000
4,000
117,120
2,400
16,800
36,000
108,480
117,600
$ 7,200
3,200
12,800
12,800
720
Comment
Cost included with fish sampling: trawl paths, species identified, counted,
weighed; 30 fish each of two species (l benthic-feeding, 1 pelagic) from 2
locations on PV Shelf, southeast and northwest from outfalls
Whole body lipid normalized muscle fillet tissue
Includes 6 DDT isomers and DDMU, DDNU, DBF
Specific congener list will be used
10% scope and 10% bid
from USAGE and EPA Estimating Guide July 2000
Use Baseline Plans
Includes boat and labor for 10 days
32 cores total; 16 stations, LACSD transects 2- thru 9 stations B & C;
duplicate cores; 4-cm increments; box core
includes 6 DDT isomers, DDMU, DDNU, DBF
specific congener list will be used
32 cores total, taken with sediment samples
includes 6 DDT isomers, DDMU, DDNU, DBF
specific congener list will be used
16 stations, LACSD transects 2- thru 9-B, C; 9 passive samplers per
station: 3 m from bed, mid-column and 5 m below surface
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Attachment 1: Remedial Alternatives Cost Estimate May09
Att-7
Table 2: Monitored Natural Recovery Details
Description Quantity
DDTs
PCBs
Fish Sampling and Analysis
Five-Year Report
Year 5 Monitoring
Subtotal A
Contingency (20% of Subtotal A)
Subtotal B
Project Mgmt (6% of Subtotal B)
Total O&M NPV for Year 5
Year 10 Monitoring
Subtotal A
Contingency (20% of Subtotal A)
Subtotal B
Project Mgmt (6% of Subtotal B)
Total O&M NPV for Year 10
Total O&M NPV Cost
Total Cost
144
144
60
1
Unit Cost
400
400
100,600
50,000
Unit
EA
EA
Total
$ 57,600
57,600
100,600
50,000
$786,900
157,380
$944,280
56,700
1,000,980
$713,700
$786,900
157,380
$944,280
56,700
1,000,980
$508,800
$1,222,500
$3,000,000
Comment
includes 6 DDT isomers, DDMU, DDNU, DBF
specific congener lisst will be used
Cost included with fish sampling: trawl paths, species identified, counted,
weighed; 30 fish each of two species (l benthic-feeding,! water column)
from 2 locations on PV Shelf southeast and northwest of the outfalls
Whole body lipid normalized muscle fillet tissue
Includes 6 DDT isomers and DDMU, DDNU, DBF
Specific congener list will be used
Five-Year Report
10% scope and 10% bid
from USACE and EPA Estimating Guide July 2000
7% discount rate
10% scope and 10% bid
from USACE and EPA Estimating Guide July 2000
7% discount rate
7% discount rate
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Attachment 1: Remedial Alternatives Cost Estimate May09
Att-8
Table 3: Containment Details
Description
Treatability Studies
Construction Capital Costs
Submerged Diffuser Placement - 1,000,000 CY
scenario
Onshore Staging Area
Crewboat (transport from shore to bargers)
Material
Dredging of Material
Crew for dredging barge
Tugboat for Dredging Barge
Crew for Tugboat for Dredging
Transport Materials to Site
Crew for Transport Barge
Placement Barge
Crew or Placement Barge
Tugboat for Placement Barge
Crew for Tugboat for Placement
Anchoring and Positioning
Survey Boat and Crew for Placement Confirmation
Subtotal A
Field Detail Allowance (5% of Subtotal A)
Subtotal B
Overhead (12% of subtotal B)
Subtotal C
Profit (6% of subtotal C)
Subtotal D
Contingency (20% of Subtotal D)
Total Direct Capital Cost
Non-Construction capital Costs
Project Management (5% of Total Direct Capital Cost)
Remedial Design (6% of Total Direct Capital Cost)
Construction Mgmt (6% of Total Direct Capital Cost)
Total Non-construction Capital Cost
Quantity
1
704
1,000,000
1,000,000
9,000
384
18,432
1,000,000
19,000
1,000,000
1 7,000
704
33,792
1
353
Unit Cost
$104,125.00
3,748.50
5.41
0.66
62.00
3,795.00
62.00
2.59
62.00
1.25
62.00
3,795.00
62.00
312,375.00
6,247.50
Unit
LS
DAY
CY
CY
HR
DAY
HR
CY
HR
CY
HR
DAY
HR
LS
DAY
Total
$6,000,000
$ 104,125
2,638,904
5,412,500
660,000
558,000
1,457,280
1,142,784
2,590,000
1,178,000
1,250,000
1,054,000
2,671,715
2,095,104
325,250
2,205,368
$25,343,080
1,267,154
26,610,234
3,193,228
29,803,462
1,178,208
31,591,670
6,318,334
$37,910,004
1,895,500
2,274,600
2,274,600
6,444,700
Comment
Studies to define area to be capped,
characterize the sediment, and test
techniques. $6 million is a rough estimate
based on 2000 pilot capping project
assumes 24 hr/day
$5.00 per cy and 8.25% tax
assumes 15-CY clamshell barge
assumes 2 crew for 24 hrs/day
assumes 24 hrs/day
assumes 3 3000-CY hopper barges
assumes 2 crew per barge for 24 hrs/day
assumes placement barges for 24 hrs/day
assumes 2 crew per barge for 24 hrs/day
assumes 2 tugboats for 24 hrs/day
assumes 2 crew per tugboat for 24
hrs/day
10% scope and 10% bid
USACE & EPA Estimating Guide (2000)
USACE & EPA Estimating Guide (2000)
USACE & EPA Estimating Guide (2000)
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Attachment 1: Remedial Alternatives Cost Estimate May09
Att-9
Table 3: Containment Details
Description
Total Capital Costs for Submerged Placement
SUBMERGED DIFFUSER UNIT COST
Construction Capital Costs
Spreading Placement — 1,000,000 CY scenario
Onshore Staging Area
Crewboat (transport from shore to barges)
Material
Dredging of Material
Crew for dredging barge
Tugboat for Dredging Barge
Crew for Tugboat for Dredging
Transport and Placement of Materials
Crew for Transport/Placement Barge
Anchoring and Positioning
Survey Boat and Crew for Placement Confirmation
Subtotal A
Field Detail Allowance (5% of Subtotal A)
Subtotal B
Overhead (12% of subtotal B)
Subtotal C
Profit (6% of subtotal C)
Subtotal D
Contingency (20% of Subtotal D)
Total Direct Capital Cost
Non-Construction Capital Costs
Project Management (5% of Total Direct Capital Cost)
Remedial Design (6% of Total Direct Capital Cost)
Construction Mgmt (6% of Total Direct Capital Cost)
Total Non-Construction Capital Cost
Total Capital Costs for Spreading Placement
SPREADING UNIT COST
Quantity
1
384
1,000,000
1,000,000
9,000
384
18,432
1,000,000
14,000
1
88
Unit Cost
$104,125.00
3,748.50
5.41
0.66
62.00
3,795.00
62.00
0.87
62.00
208,250.00
6,247.50
Unit
CY
LS
DAY
CY
CY
HR
DAY
HR
CY
HR
LS
DAY
CY
Total
$44,355,000
44
$ 104,125
1,439,424
5,412,500
660,000
558,000
1,457,280
1,142,784
870,000
868,000
208,250
549,780
13,270,143
663,507
13,933,650
1,672,038
15,605,203
936,341
16,542,029
1,654,203
18,196,232
909,812
1,091,774
1,091,774
3,093,400
$21,290,000
21
Comment
Assumes 24 hrs/day
$5.00 per CY and 8.5% tax
assumes 2 15-CY clamshell barge
assumes 2 crew per barge for 24 hrs/day
assumes 2 tugboats for 24 hrs/day
assumes 2 crew per tugboat for 24 hr/day
assumes 5 1000-CY bottom dump barges,
split hull
assumes 2 crew per barge for 24 hrs/day
10% scope and 10% bid
USACE & EPA Estimating Guide (2000)
USACE & EPA Estimating Guide (2000)
USACE & EPA Estimating Guide (2000)
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Attachment 1: Remedial Alternatives Cost Estimate May09
Att-10
Table 3: Containment Details
Description
Monitoring- During- Alt. 3 Construction
Resuspension and plume monitoring arrays
(automated resuspension surveillance system)
Sediment Profile Imagery (SPI)
Sediment and Water Column Sampling
Plans (SAP, QAP, HSP)
Equipment Rental
Materials
Shipping/Transport
Report
Sediment Analysis
Sample Preparation
Water Content
Total organic content (TOC)
Grain Size
DDTs
PCBs
Water Column Analysis
DDTs, total
PCBs, total
DDTs, dissolved
PCBs, dissolved
Subtotal A
Contingency (20% of Subtotal A)
Subtotal B
Project Mgmt (5% of Subtotal B)
Total Construction Cap Monitoring
Quantity
6
3
1
16
1
1
1
360
360
360
360
360
360
24
24
24
24
Unit Cost
$110,000
$45,000
$ 45,000
6,300
4,000
3,000
200,000
245
$5
35
75
205
245
206
245
206
245
Unit
EA
LS
LS
DAY
LS
LS
LS
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
Total
$ 660,000
$ 135,000
$ 45,000
100,800
4,000
3,000
200,000
88,200
1,800
12,600
27,000
73,800
88,200
4,944
5,880
4,944
5,880
1,461,048
292,210
1,753,258
105,195
$1,900,000
Comment
Assumes placement at 6 locations during
construction
Assumes 50 locations for pre-, during, and
post-construction monitoring
Includes boat and labor for 1 6 days
Assumes 12 core locations for a depth of
60 cm with 4-cm sample increments for
1 80 samples for during and post-
construction monitoring
10
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Attachment 1: Remedial Alternatives Cost Estimate May09
Att-11
Table 3: Containment Details
Description
O & M Costs
Sediment Monitoring - Five-Year Review
Sediment Profile Imagery (SPI)
Sediment and Water Column Sampling
Plans (SAP, QAP, HSP)
Equipment Rental
Materials
Shipping/Transport
Report
Sediment Analysis
Sample Preparation
Water Content
Total organic content (TOC)
Grain Size
DDTs
PCBs
Water Column Analysis
DDTs, total
PCBs, total
DDTs, dissolved
PCBs, dissolved
Subtotal A
Contingency (20% of Subtotal A)
Subtotal B
Project Mgmt (5% of Subtotal B)
O&M Sediment Monitoring for Year 5
Total O&M NPV for Year 5
Quantity
1
0
16
1
1
1
300
300
300
300
300
300
24
24
24
24
Unit Cost
$45,000
$45,000
$6,300
$4,000
3,000
200,000
245
$5
35
75
205
245
205
245
205
245
Unit
LS
LS
DAY
LS
LS
LS
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
Total
$45,000
$100,800
$ 4,000
3,000
200,000
73,500
1,500
10,500
22,500
61,500
73,500
4,944
5,880
4,944
5,880
617,448
123,490
740,938
37,047
$778,000
554,700
Comment
Assumes 50 locations for each event
Use same plans as for baseline monitoring
Includes boat and labor for 1 6 days for
each sampling event
Assumes 12 core locations to a depth of
100 cm with 4-cm sample increments for
300 total samples for each sampling event
DDT 6 isomers &DDMU/DDNU/DBP
specific congener list wll be used
Assumes 12 locations at depths/location
(mid-winter near bottom)
DDT 6 isomers &DDMU/DDNU/DBP
specific congener list wll be used
DDT 6 isomers &DDMU/DDNU/DBP
specific congener list wll be used
10% scope and 10% bid
From USAGE and EPA Estimating Guide
(July 2000)
annual rate
7% discount rate
11
-------
Attachment 1: Remedial Alternatives Cost Estimate May09
Att-12
Monitoring During Alt. 4 Cap Construction
Description
Resuspension and plume monitoring arrays
(automated resuspension surveillance system)
Sediment Profile Imagery (SPI)
Sediment and Water Column Sampling
Plans (SAP, QAP, HSP)
Equipment Rental
Materials
Shipping/Transport
Report
Sediment Analysis
Sample Preparation
Water Content
Total organic content (TOC)
Grain Size
DDTs
PCBs
Water Column Analysis
DDTs, total
PCBs, total
DDTs, dissolved
PCBs, dissolved
Subtotal A
Contingency (20% of Subtotal A)
Subtotal B
Project Mgmt (5% of Subtotal B)
Total Construction Cap Monitoring
Quantity
12
6
1
25
1
1
1
720
720
720
720
720
720
48
48
48
48
Unit Cost
$110,000
$45,000
$ 45,000
6,300
4,000
3,000
200,000
245
$5
35
75
205
245
206
245
206
245
Unit
EA
LS
LS
DAY
LS
LS
LS
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
Total
$ 1,320,000
$ 270,000
$ 45,000
157,500
4,000
3,000
200,000
176,400
3,600
25,200
54,000
147,600
1 76,400
9,888
11,760
9,888
11,760
2,626,000
525,000
3,151,000
158,000
$3,309,000
Comment
Assumes placement at 6 locations during
2 construction seasons for a total of 12
locations
Assumes 100 locations for pre-, during,
and post-construction monitoring
Includes boat and labor for 25 days
Assumes 24 core locations for a depth of
60 cm with 4-cm sample increments for
360 samples for during and post-
construction monitoring
12
-------
Attachment 1: Remedial Alternatives Cost Estimate May09
Att-13
Monitoring During Alt. 4 Cap Construction
Description
O & M Costs
Sediment Monitoring - Five- Year Review
Sediment Profile Imagery (SPI)
Sediment and Water Column Sampling
Plans (SAP, QAP, HSP)
Equipment Rental
Materials
Shipping/Transport
Report
Sediment Analysis
Sample Preparation
Water Content
Total organic content (TOC)
Grain Size
DDTs
PCBs
Water Column Analysis
DDTs, total
PCBs, total
DDTs, dissolved
PCBs, dissolved
Subtotal A
Contingency (20% of Subtotal A)
Subtotal B
Project Mgmt (5% of Subtotal B)
O&M Sediment Monitoring for Year 5
Total O&M NPV for Year 5
Quantity
1
0
25
1
1
1
480
480
480
480
480
480
48
48
48
48
Unit Cost
$45,000
$45,000
$6,300
$4,000
3,000
200,000
245
$5
35
75
205
245
205
245
205
245
Unit
LS
LS
DAY
LS
LS
LS
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
Total
$45,000
$157,500
$ 4,000
3,000
200,000
117,600
2,400
16,800
36,000
98,400
117,600
9,888
11,760
9,888
11,760
841,600
168,300
1,009,900
50,500
$1,060,400
756,000
Comment
Assumes 50 locations for each event
Use same plans as for baseline monitoring
Includes boat and labor for 25 days for
each sampling event
Assumes 24 core locations to a depth of 80
cm with 4-cm sample increments for 480
total samples for each sampling event
DDT 6 isomers &DDMU/DDNU/DBP
specific congener list wll be used
Assumes 24 locations at depths/location
(mid-winter near bottom)
DDT 6 isomers &DDMU/DDNU/DBP
specific congener list wll be used
DDT 6 isomers &DDMU/DDNU/DBP
specific congener list wll be used
10% scope and 10% bid
From USAGE and EPA Estimating Guide
(July 2000)
annual rate
7% discount rate
13
-------
Attachment 1: Remedial Alternatives Cost Estimate May09
Att-14
Summary of Containment Costs
Treatability Studies
Low Impact, (e.g., clamshell) Placement
Spreading Placement
Total cover*
Total material placement cost
Construction Monitoring
NPV 5-Yr Monitoring
TOTAL
Unit Cost
NA
$44 CY
$21 CY
Capital
$6,000,000
Alt. 3: Enhanced MNR
300,000 CY
564,000 CY
864,000 CY
$6,000,000
$25,050,000
$1,900,000
$554,700
$33,500,000
Alt. 4: Containment
600,000 CY
1,176,000 CY
1,776,000 CY
Based on 45-cm cover, includes 10% increase for material loss
$6,000,000
$51,100,000
$3,309,000
$756,000
$61,200,000
14
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