PB98-964509
EPA 541-R98-083
October 1998
EPA Super-fund
Record of Decision:
San Gabriel Valley (Area 4)
Puente Valley OU
La Puente, CA
9/30/1998
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INTERIM RECORD OF DECISION
SAN GABRIEL VALLEY SUPERFUND SITE
PUENTE VALLEY OPERABLE UNIT
CITY OF INDUSTRY, CALIFORNIA
Volume 1
September 1998
United States Environmental Protection Agency
Region IX - San Francisco, California
SCO/982650001.00CM-97
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Parti
Decision Summary
SCO/9B2670004.DOC/I-97
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Contents
Section Page
Declaration iii
Part I Decision Summary
1 Site Location and Description 1-1
1.1 Location and Topography 1-1
1.2 Climate 1-2
1.3 Land Use 1-2
1.4 Surface Water 1-2
1.5 Geology and Hydrogeology 1-3
1.6 Ground-water Management 1-5
2 Site History 2-1
2.1 Overview of Site Activities 2-1
2.2 Remedial Investigation Activities 2-1
3 Enforcement Activities 3-1
4 Scope and Role of Document 4-1
5 Highlights of Community Participation 5-1
6 Summary of Site Characteristics 6-1
7 Summary of Site Risks 7-1
7.1 Identification of Chemicals of Potential Concern 7-1
7.2 Exposure Assessment 7-1
7.3 Toxicity Assessment 7-2
7.4 Risk Characterization Summary 7-4
8 Description of Remedial Alternatives 8-1
8.1 Alternative 1No Action 8-1
8.2 Alternative 2Ground-water Monitoring 8-2
8.3 Alternative 3Ground-water Control in the Shallow and Intermediate Zones
at the Mouth of the Valley 8-2
8.4 Alternative 4Ground-water Control in the Shallow and Intermediate Zones
at the Mouth of the Valley and in the Intermediate Zone at Mid-Valley 8-3
9 Summary of Comparative Analysis of Alternatives 9-1
9.1 Overall Protection of Human Health and the Environment 9-2
9.2 Compliance with ARARs ; 9-3
9.3 Long-Term Effectiveness 9-3
9.4 Reduction of Toxicity, Mobility, and Volume Through Treatment 9-4
9.5 Short-Term Effectiveness 9-5
9.6 Implementability 9-6
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CONTENTS, CONTINUED
Section Page
9.7 Cost 9-8
9.8 State Acceptance 9-8
9.9 Community Acceptance 9-9
10 Selected Remedy 10-1
10.1 Performance Criteria 10-1
11 Applicable or Relevant and Appropriate Requirements (ARARs) 11-1
11.1 Chemical-specific ARARs 11-2
11.2 Location-specific ARARs 11-3
11.3 Action-specific ARARs 11-4
11.4 ARARs Waivers :.... 11-8
12 Documentation of Significant Changes 12-1
13 Statutory Determinations 13-1
13.1 Protection of Human Health and the Environment 13-1
13.2 Compliance with ARARs 13-1
13.3 Cost-Effectiveness 13-1
13.4 Community Acceptance 13-1
13.5 Utilization of Permanent Solutions and Alternative Treatment Technologies
to the Maximum Extent 13-2
13.6 Preference for Treatment as a Principal Element 13-2
13.7 Five-Year Reviews 13-2
14 References 14-1
Tables
1 ARARs for Chemicals of Potential Concerns
2 Estimated Total Noncancer Hazard Index from Domestic Use of Ground Water
3 Estimated Total Excess Lifetime Cancer Risk from Domestic Use of Ground Water
4 Cost Comparison of Alternatives
5 Puente Valley OU RI/FSChemical-Specific ARARs and TBCs
6 B7 Production Wells
Figures
1 Vicinity Map
2 1997 Shallow VOC Contamination
3 1997 Intermediate VOC Contamination
4 Qualitative Criteria Evaluation Matrix
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Declaration
Site Name and Location
This Interim Record of Decision (ROD) addresses the contamination at the Puente Valley
Operable Unit (PVOU) located within the San Gabriel Valley Superfund Site in Los Angeles
County, California.
Statement of Basis and Purpose
This ROD presents the selected interim remedial action for the PVOU of the San Gabriel
Valley Superfund Site in accordance with the Comprehensive Environmental Response,
Compensation and Liability Act of 1980,42 U.S.C. §§ 9601 et. seq., as amended by the
Superfund Amendments and Reauthorization Act of 1986 (SARA) (collectively referred to
herein as CERCLA) and to the extent practicable, the National Oil and Hazardous
Substances Pollution Contingency Plan, 40 CFR Part 300 (NCP). This decision is based on
the Administrative Record for this site.
The State of California, acting through the California Department of Toxic Substances
Control (DTSC) and the Los Angeles Regional Water Quality Control Board (RWQCB),
concur with the selected remedy.
Assessment of the Site
The response action selected in this ROD is necessary to protect the public health or welfare
or the environment from actual or threatened releases of hazardous substances into the
environment.
Description of the Interim Action
This ROD addresses ground water contaminated with volatile organic compounds (VOCs).
EPA's objective is to protect human health and the environment. The selected remedy is
containment of ground water contaminated with VOCs in the shallow and intermediate
zones at the mouth of Puente Valley to prevent further migration of existing ground-water
contamination. This remedy includes performance criteria that will require extraction and
treatment of contaminated ground water at certain locations along the downgradient edge
of the contamination and will require continued monitoring and evaluation at other
locations. Treated ground water will be provided to local water purveyors or discharged to
Puente Creek, immediately upstream of San Jose Creek. In addition, this remedy includes
monitoring in the shallow, intermediate, and deep ground-water zones at mid-valley and at
the mouth of the valley.
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DECLARATION
Statutory Determinations
The selected remedy is protective of human health and the environment, complies with
federal and state requirements that are legally applicable or relevant and appropriate to the
remedial action and is cost effective. Performance criteria and remediation components of
the selected remedy satisfy the statutory preference for remedies that employ treatment that
reduces toxicity, mobility, or volume as a principal element.
Because this remedy will result in hazardous substances remaining onsite above health-
based levels, a review will be conducted at least once every five years after commencement
of remedial action to ensure that the remedy continues to provide adequate protection of
human health and the environment.
Keith A. Takata Date
Director of Superfund Division
U.S. Environmental Protection Agency, Region EX
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Part I Decision Summary
1 Site Location and Description
1.1 Location and Topography
This interim Record of Decision (ROD) covers the Puente Valley Operable Unit (PVOU)
located within the southeastern portion of the San Gabriel Valley (Figure 1), approximately
25 miles from the Pacific coast, in eastern Los Angeles County. Located within the San
Gabriel Valley is the San Gabriel Basin, a broad piedmont plain that slopes gradually to the
southwest at a gradient of approximately 65 feet per mile (CDWR, 1934). This structural
basin is a natural ground-water reservoir that collects rainfall on the valley floor and run-off
from the surrounding highlands, recharging the ground-water aquifer.
The San Gabriel Basin is bounded to the southwest, south, and southeast by a crescent-
shaped system of low hills. The hills making up the system, from west to east, are the
Repetto, Merced, Puente, and San Jose Hills. The only significant break along this boundary
falls between the Merced and Puente Hills at Whittier Narrows. Whittier Narrows is the
lowest point in the San Gabriel Valley and is the exit for the San Gabriel River and Rio
Hondo and their tributaries, which serve as the drainage system for the valley.
The Puente Valley is a "horn-shaped" valley with a mouth that opens into the Main San
Gabriel Ground-Water Basin at the west (CDWR, 1934). It covers a surface area of
10,900 acres, and is approximately 12-1/2 miles long and ranges from less than 2 miles wide
at the eastern end to over 3 miles wide at the western end. Puente Valley varies in elevation
from over 800 feet above mean sea level (msl) at the eastern boundary to approximately
300 feet msl at the western boundary. Puente Valley is bounded on the north by the San
Jose Hills and on the south by the Puente Hills.
The surface geology in the Puente Valley is a mixture of stream channel deposits from San
Jose Creek, consisting of clay, silt, sand, and minor amounts of gravel (EPA, 1993c). The
creek, a tributary to the San Gabriel River, flows through the center of the valley and serves
as the major surface water drainage in the area.
The eastern boundary of the PVOU coincides with the boundary of the San Gabriel Valley at
the eastern end of Puente Valley. The western boundary of the PVOU extends beyond the
end of the Puente Valley into the Main San Gabriel Valley, and incorporates production
wells located north and west of the Puente Valley (EPA, 1993c).
The PVOU spans portions of both the Puente Ground-Water Basin and the Main San Gabriel
Ground-Water Basin. Although there is no exact dividing line between these basins, the
general boundaries are described in the Puente Narrows Agreement, dated May 8,1972,
between the Puente Basin Water Agency and the Upper San Gabriel Valley Municipal Water
District. The general area of division between the basins is the Puente Narrows, which is
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1 SITE LOCATION AND DESCRIPTION
defined in the Puente Narrows Agreement as "The subsurface geologic constriction at the
downstream boundary of Puente Basin."
1.2 Climate
The region in which Puente Valley is located has a Mediterranean climate. Like most of the
South Coastal Basin, intermittent rain occurs during the winter; and summers are
predominantly dry. The mean seasonal temperature of the Puente Valley varies from the
upper 50 degrees Fahrenheit (°F) range in the winter to the mid 80°F range in the summer.
The average annual temperature is 62°F. Temperatures rarely drop below freezing;
however, in the San Gabriel Valley, values have been recorded as low as 22°F and as high as
1110F(CDWR,1966).
The prevailing wind direction is from the south to southwest. During the fall and winter
months, however, Santa Ana wind conditions, unique to Southern California, are known to
occasionally affect the local weather, increasing temperatures and bringing warm dry air
from the northeast (James M. Montgomery, 1992).
All precipitation in the Puente Valley occurs as rainfall. Based on information presented in
the Ninth Annual Report (Puente Basin Watermaster, 1995), the average annual rainfall for
the Puente Valley is approximately 18 inches per year, with approximately 77 percent of the
precipitation occurring between December and March. Within the valley, precipitation
levels vary slightly, mainly as a result of differences"in ground surface elevation.
Precipitation levels in the valley are known to fluctuate significantly from year to year,
creating periods of above-normal rainfall levels interspersed with periods of persistent
drought.
1.3 Land Use
The majority of the Puente Valley is highly industrialized and is occupied by the City of
Industry, an incorporated city that covers approximately 11 square miles. According to
information provided by the City of Industry (City of Industry, 1995), 96 percent of the city
is zoned for industrial uses; and 4 percent is zoned for commercial purposes. Nearly
85 percent of the land within the boundaries of the City of Industry has been developed, and
accommodates approximately 1,700 businesses. Currently, the City of Industry is planning
to develop an additional 1,500 acres, all zoned for industrial and commercial uses. The
small amount of land within the City of Industry allotted for residential purposes is
occupied by 631 residents (City of Industry, 1995). The Cities of La Puente and Walnut also
occupy portions of the Puente Valley at the northwestern and eastern borders, respectively.
The portions of the PVOU occupied by these cities are zoned primarily for residential
purposes. Prior to the early 1950s, Puente Valley was primarily used for agricultural
purposes.
1.4 Surf ace Water
Two major stream systems carry surface flow from the San Gabriel Valley: the San Gabriel
River and the Rio Hondo and their tributaries. The headwaters for these two systems are in
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1 SITE LOCATION AND DESCRIPTION
the San Gabriel Mountains. The systems transverse the San Gabriel Valley in a
southwesterly direction and exit the valley at Whittier Narrows (EPA, 1993c). Except in the
case of significant storms, these channels do not carry much natural run-off (EPA, 1993c).
Nearly all of the stream channels contributing to the drainage of the San Gabriel Valley have
been modified with the addition of concrete lining. This lining minimizes recharge of the
aquifer by surface water flow, except in portions of the San Gabriel River that are not lined
and are intended as areas for ground-water recharge. In addition, the major channels have
been supplemented with flood control reservoirs.
The majority of the flow within the San Gabriel River is contributed by run-off draining
from the San Gabriel Mountains, directly into the river (California Department of Water
Resources [CDWR], 1966). A portion of the flow, however, is contributed by the Walnut
and San Jose Creeks and by the tributaries of the Raymond Basin (to the northwest of the
San Gabriel Valley).
San Jose Creek, a tributary of the San Gabriel River, is the only surface water feature within
the PVOU with continuous flow. Continuous surface water flows in San Jose Creek are
sustained by discharge from the Pomona Valley Treatment Plant, industrial wastewater
discharge, treated ground-water discharge from one industrial facility, and intermittent
ground water discharging through weepholes.
Most of the stretch of San Jose Creek that runs through the PVOU is concrete lined.
However, near the western boundary of the PVOU, the last approximate 1-1/3 miles of the
channel are unlined. The lined portion of the channel is underlain by a subdrain system
consisting of a series of longitudinal perforated collector pipes embedded in a coarse drain
material, which is underlain by a shallow layer of filter material. The subdrain collector
pipes are designed to relieve hydrostatic pressure from building up under the concrete
channel, by allowing shallow ground water from beneath the channel to flow into the
surface water channel either through weep holes or discharge pipes in the channel walls.
A portion of the surface water flow in San Jose Creek is allowed to recharge ground water,
both in unlined reaches of the San Jose Creek and San Gabriel River and in the San Gabriel
River Spreading Grounds. These spreading grounds are located in the Central Basin, along
the San Gabriel River, downstream of where San Jose Creek feeds into the river.
1.5 Geology and Hydrogeology
1.5.1 San Gabriel Valley/Basin
The Main San Gabriel Basin is filled with alluvial deposits, primarily of Quaternary age,
which overlie relatively impermeable rock. These deposits are 2,000 to 4,000 feet thick over
the center of the basin and range between approximately 250 to 800 feet thick at the basin
outlet in Whittier Narrows. The distribution of the sediments deposited in the basin is
controlled both by the distance from the sediment source and by the position relative to
river and tributary courses. Across the Main San Gabriel Basin, the alluvial deposits show a
high degree of variability in sediment type, both vertically and laterally (EPA, 1993c).
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t SITE LOCATION AND DESCRIPTION
There are three general water-bearing formations of the Main San Gabriel Basin. The Upper
Pico Formation is a Pliocene marine deposit, while the Older and Recent Alluvium are
nonmarine sediments of Recent and Pleistocene age (CDWR, 1966). The Upper Pico
Formation is a semiconsolidated marine deposit, consisting mainly of sand, silt, and clay
interbedded with gravels. In the vicinity of Whittier Narrows, the formation is water
bearing. Where it crops out in the Repetto, Merced, and Puente Hills, however, it contains
little or no water (CDWR, 1966).
Older Alluvium refers to those alluvial deposits that were lain down during the late and
possibly early Pleistocene period. It tends to occur as unsorted debris, yellowish to reddish
brown in color. Grain sizes range from fine silt to boulders over 2 feet in diameter. In the
Main San Gabriel Basin, most of the subsurface sediment is made up of Older Alluvium
(CDWR, 1966).
Recent Alluvium tends to be light-gray to buff in color and is made up of a range of coarser
materials: boulders, gravels, and sands. Because of its coarse nature, Recent Alluvium is
efficient in the absorption, transmission, and yielding of water.
Major structural features controlling regional ground-water flow in the San Gabriel Basin
include the topographic highs (i.e., San Gabriel Mountains and southern hills) and
topographic lows (i.e., San Gabriel Basin and subbasins). Four major faults in the San
Gabriel Basin potentially impact ground-water flow: the Sierra Madre Fault System, the
Raymond Fault, the Lone Hill-Way Hill Fault, and the Workman Hill Fault. As discussed in
the Feasibility Study (FS), other faults (i.e., Walnut Creek Fault and Handorf Fault) also
appear to exert some influence on ground-water movement in the San Gabriel Basin.
1.5.1.1 Puente Valley/Basin
Puente Valley is bounded on the north by the San Jose Hills and on the south by the Puente
Hills. The San Jose Hills and Puente Hills are composed primarily of marine sedimentary
rocks ranging from Pliocene to Miocene age (1.6 to 23.4 million years). Material derived
from these hills has contributed a large portion of the alluvium in the Puente Valley.
The materials making up the Puente and San Jose Hills have reported hydraulic
conductivities generally two orders of magnitude less than the alluvial deposits filling the
Puente Valley. The deposits filling Puente Valley are derived from the Puente and San Jose
Hills and consist of alluvium interbedded with other deposits. The fill deposits range in
thickness from approximately 1,300 feet in the northwestern portion of the PVOU to less
than 25 feet thick in the extreme eastern portion and valley perimeter. They consist, to a
large extent, of clay and silry clay with lenses of sand and gravel. Some of these permeable
lenses have been shown to persist throughout much of the valley.
The alluvial deposits filling Puente Valley were derived from two primary sources:
materials derived locally from the San Jose Hills to the north and Puente Hills to the south
(Older Alluvium), and Recent Alluvium deposited by San Jose Creek (CDWR, 1934). Older
Alluvium is exposed over much of the periphery of the Puente Valley, with fingers of
Recent Alluvium exposed up the center of the valley into the eastern extremities. The Older
Alluvium consists of debris ranging in size from fine silt to medium boulders, derived
primarily from the surrounding hills.
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1 SITE LOCATION AND DESCRIPTION
The Puente Formation underlies the alluvium and is considered to be relatively nonwater-
bearing bedrock. This bedrock forms a somewhat irregular basement in the valley and, in
places, protrudes through the alluvium, creating isolated outcrops of bedrock within the
basin (CDWR, 1966).
1.5.2 Hydrogeology
According to the CDWR report (1966), the Main San Gabriel Ground-Water Basin comprises
approximately 167 square miles of water-bearing valley land. The maximum depth of
alluvial fill within the main basin is unknown, though it is expected to be between 2,000 and
4,000 feet (CDWR, 1934; and EPA, 1993c). The estimated total storage capacity of the Main
San Gabriel Basin is 10.44 million acre-feet (CDWR, 1979); however, because of the great
depth of the basin and the subsequent inaccessibility of much of the ground water, the
available supply of the basin is much less.
The majority of natural inflow to the Main San Gabriel Basin is in the form of surface water,
originating as precipitation and entering through stream channels or as overland flow.
Subsurface flow crosses into the San Gabriel Valley from the Raymond Ground-Water Basin
across the Raymond fault on the northwest, and from the Chino Ground-Water Basin on the
east.
The total water available to the Puente Basin is supplied primarily by precipitation on the
valley floor and adjacent watershed, and by underflow from surrounding areas. Currently,
water is also being imported into the Puente Basin from the Pomona Water Reclamation
Plant and from the Metropolitan Water District of Southern California (Metropolitan) by the
Rowland and Walnut Water Districts (Puente Basin Watermaster, 1995).
Because the Puente Basin is constrained on the north and south by bedrock outcrops,
ground water generally flows toward the west and northwest. Evaluation of ground-water
elevation data collected in February 1996 indicates that the horizontal hydraulic gradient for
the area east of Azusa Avenue ranges from 0.015 to 0.033. In the mid-valley area, the
horizontal gradient ranges from 0.004 to 0.007. Gradients in the mouth of the valley (i.e.,
northwest of Hacienda Boulevard) range from 0.006 to 0.010. Ground-water flow velocity in
the PVOU has been reported to range between 0.6 foot/day and 3.7 feet/day and may be
somewhat higher near the area of pumpage at the mouth of the valley. Flow velocity is
directly influenced by the horizontal gradient. Therefore, flow velocities are relatively
higher in areas of higher horizontal gradient (EPA, 1993c).
1.6 Ground-water Management
Administratively, two ground-water basins exist within the PVOU: the Puente Basin and the
Main San Gabriel Basin. The complete Puente Basin and southeast tip of the Main San
Gabriel Basin are located within the PVOU. The rights to pump ground water from these
basins are adjudicated (i.e., assigned to specified users in accordance with a court
judgment).
Water rights in the Main San Gabriel Basin were adjudicated in a stipulated judgment by the
Superior Court of Los Angeles County in 1972 (amended in 1989), in the case, Upper San
Gabriel Valley Municipal Water District v. City ofAlhambra (Case Number 924128). This
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1 SITE LOCATION AND DESCRIPTION
adjudication resulted in assigning water rights to approximately 50 parties that each hold
rights to greater than one percent of the natural safe yield of the basin (152,700 acre-feet per
year, established in the judgment), and approximately 100 parties that each hold rights to
less than 1 percent of the natural safe yield.
The judgment also establishes the duties of a Watermaster, which include annually
determining an operating safe yield for the basin, monitoring pumpers' compliance with the
judgment, issuing permits for all new and increased pumping in the basin, and preparing an
annual report that includes details of pumping activities in the basin. The amount of
ground water that each water rights holder can pump in any year is adjusted by prorating
the pumper's prescriptive rights (percentage of natural safe yield) by the operating safe
yield, as established by the Watermaster.
The majority of the ground water pumped from the Main San Gabriel Basin is used for
drinking water, supplied to the public by purveyors that are regulated as public water
supply systems. Annually, pumping typically equals or exceeds the operating safe yield of
the basin. When excess extraction occurs, the judgment has established provisions for
assessing pumpers the cost of importing water to replenish the excess amount extracted.
The water rights in the Puente Basin were adjudicated in a stipulated judgment by the
Superior Court of Los Angeles County in 1986, in the case, Puente Basin Water Agency, et al.,
v. City of Industry, et al. (Case Number C369220). This adjudication resulted in assigning
water rights to five primary producers in the basin. As with the Main San Gabriel Basin, the
Puente Basin judgment established the duties of a Watermaster, which are similar in nature
to the Main San Gabriel Basin Watermaster.
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2 Site History
2.1 Overview of Site Activities
The San Gabriel Valley has been the subject of environmental investigation since 1979 when
ground water contaminated with volatile organic compounds (VOCs) was first identified.
In May 1984, four broad areas of contamination within the basin were listed as San Gabriel
Areas 1 through 4 on the Environmental Protection Agency's (EPA's) National Priorities List
(NPL). EPA subsequently divided the basin into eight operable units (OUs) to provide a
means of describing hydrogeology and contaminant distribution, and planning remedial
activities in the basin.
In 1986, data were compiled and reviewed to develop a preliminary conceptual
hydrogeologic model of the San Gabriel Valley, as described in the Supplemental Sampling
Program (SSP) Report (EPA, 1986). The results of the SSP investigations provided much of
the basis for planning the remedial investigations that have been performed in the San
Gabriel Valley since 1986. The Interim San Gabriel Basin Remedial Investigation Report
(EPA, 1992b) describes these investigations and incorporates their results into an integrated
discussion of EPA's understanding of hydrogeologic conditions in the basin.
In April 1993, EPA issued a draft Statement of Work (SOW) for an Interim remedial
investigation/feasibility study (RI/FS) to address the PVOU. Following negotiations
between EPA and the Puente Valley Steering Committee (PVSC), an Administrative Order
on Consent (AOC) was executed in which the PVSC agreed to perform the investigation
detailed in the current SOW, which is a part of the AOC.
2.2 Remedial Investigation Activities
EPA developed the RI/FS process for conducting environmental investigations under
Superfund. The RI/FS approach is the methodology that the Superfund program has
established for characterizing the nature and extent of risks posed by uncontrolled
hazardous waste sites to evaluate potential remedial options.
The RI serves as a mechanism to collect data for site characterization. The FS serves as the
mechanism for development, screening, and evaluation of potential remedial alternatives.
The goals of the RI/FS did not include identifying or evaluating soil and soil gas
contamination, or developing alternatives for remedial action to address shallow ground-
water contamination that should be addressed through parcel- or source-specific actions
(COM, 1993). Intrinsic to the adopted approach was the assumption that parcel- or source-
specific actions will continue to be taken under the purview of the Los Angeles Regional
Water Quality Control Board (RWQCB). Existing data indicate that source control actions
under the purview of the RWQCB have a significant beneficial effect on water quality in the
shallow zone.
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2 SITE HISTORY
The goals1 of the RI/FS process for the PVOU were to:
Assess the nature and extent of ground-water contamination in the PVOU to support an
EPA decision on one or more interim actions, which may include a ground-water
contamination migration control action in the northwestern Puente Valley.
Assess water quality in the San Jose Creek channel and subdrain during ground-water
discharge conditions to assess the potential for increased contaminant migration in the
channel and subdrain system, and to evaluate the exposure risk associated with such
migration.
Develop, screen, and analyze alternatives for appropriate remedial action(s) to manage
the vertical and horizontal migration of regional contaminated ground water from
highly contaminated to less contaminated (i.e., an order of magnitude less) portions of
the PVOU. Such remedial action(s) will focus on contaminated regional ground water
that is not being managed within the boundary of a specific parcel of property through
parcel-specific response.
An Interim Remedial Investigation was conducted for the PVOU during the period
September 1994 through February 1996. As detailed in the Interim RI/FS SOW and Work
Plan, the Interim RI consisted of two primary components, a ground-water investigation of
the PVOU and a surface water/ground-water interaction investigation of San Jose Creek.
The final RI Report was submitted to EPA in May 1997.
An FS was performed for the PVOU in 1996 and 1997. The FS identified remedial action
objectives, assembled remedial alternatives, and provided an evaluation of the alternatives
versus nine evaluation criteria that EPA established. EPA issued the Final FS Report in May
1997.
'The 'goals' stated in the SOW and Work Plan were used to identify the scope of the PVOU RI/FS. They should not be
confused with 'remediation goals' developed under the NCP.
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3 Enforcement Activities
EPA began its enforcement efforts in the PVOU in 1985 by searching historical federal, state,
and local records for evidence of chemical usage, handling, and disposal in the Puente
Valley area. At approximately the same time, the RWQCB initiated its Well Investigation
Program (WIP) to identify sources of ground-water contamination. In 1989, EPA entered
into a cooperative agreement with the RWQCB to expand the WIP program, to assist EPA in
determining the nature and extent of the sources of ground-water contamination in the San
Gabriel Valley, and to identify responsible parties. The RWQCB directly oversees facility-
specific investigations in the Puente Valley area; EPA helps fund these activities and, when
necessary, uses its enforcement authority to obtain information and ensure that facility
investigations are promptly completed.
As of September 1998, the RWQCB has sent chemical use questionnaires to approximately
730 facilities in the Puente Valley area; inspected approximately 650 of these facilities; and
directed approximately 190 facilities to perform soil, soil gas, and/or ground-water
investigations. EPA has concurrently used its authority under Section 104(e) of the
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) to
request information from more than 150 current and former owners and operators in the
PVOU. From these investigations, EPA has identified 50 facilities as sources of ground-
water contamination for the PVOU.
From 1990 through 1993, EPA sent General Notice of Liability letters to approximately
109 entities in and around the Puente Valley area. On May 26,1993, EPA sent Special Notice
letters to 58 potentially responsible parties (PRPs), requesting that these parties present a
good faith offer to perform the RI/FS for the PVOU. Forty-two of these PRPs formed the
PVSC and in September 1993 entered into an AOC with EPA to conduct the RI/FS. Also in
September 1993, EPA issued a Unilateral Administrative Order (UAO) to two PRPs, Goe
Engineering and Diversey Corporation, that failed to present a good faith offer. Diversey
Corporation completed the activities that the UAO required in 1996, and the PVSC and EPA
completed the RI/FS in May 1997.
Since 1993, EPA and the RWQCB have continued to investigate potential sources of
contamination. In June 1997, EPA notified 11 additional entities that they had been
identified as PRPs. EPA is now in the process of identifying a final group of PRPs for the
PVOU. EPA will contact the new PRPs shortly after the ROD is issued. EPA anticipates
issuing Special Notice letters to the Puente Valley PRPs a few months after all of the PRPs
have been identified; however, EPA may offer to settle with some of the smaller PRPs in lieu
of issuing Special Notice letters.
EPA and the RWQCB have undertaken enforcement activities elsewhere in the San Gabriel
Valley, including facility investigations, issuance of CERCLA section 104(e) requests for
information, issuance of General and Special Notice letters, and filing of cost recovery
litigation. PRPs in the El Monte and South El Monte OUs have entered into Administrative
Consent Orders to perform the RI/FS for their respective OUs. EPA also issued UAOs to
two parties in the El Monte OU. In the Baldwin Park OU, EPA issued a ROD in March 1993,
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3 ENFORCEMENT ACTIVITIES
and in May 1997 sent Special Notice letters to 19 PRPs seeking performance of the remedial
design and remedial action (RD/RA). Soon thereafter, perchlorate contamination was
discovered in the Baldwin Park OU, leading EPA to initiate an amendment of the ROD and
extend the deadline for the submission of a good faith offer to July 1999.
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4 Scope and Role of this Document
There are four areas of ground-water contamination in the San Gabriel Basin aquifer listed
on the NPL as San Gabriel Valley Areas 1 through 4. The San Gabriel Valley has been
divided into eight different OUs: Alhambra, Baldwin Park, El Monte, South El Monte,
Whittier Narrows, Suburban, Richwood, and Puente Valley (Figure 1). The PVOU
addresses ground-water contamination corresponding to the San Gabriel Valley Area 4 NPL
site.
EPA initiated an overall RI/FS for the entire San Gabriel site in 1984 with a preliminary
investigation termed the Supplemental Sampling Program. This investigation was
completed in 1986 and included the sampling of 70 existing ground-water wells for a full
range of organic contaminants, collection and evaluation of existing data, and regional
ground-water flow modelling. Data were compiled and reviewed to develop a preliminary
conceptual hydrogeologic model of the San Gabriel Valley. The results of the investigations
provided much of the basis for planning the remedial investigations that have been
performed in the San Gabriel Valley since 1986.
The PVOU is classified as an interim action because it is intended to control the migration of
contamination. Additional remediation may be needed to clean up VOC contamination
remaining in the ground water. EPA will use information collected during operation of the
selected remedy to help determine the need for additional actions and the nature of the final
remedy. This interim action will neither be inconsistent with, nor preclude, implementation
of the final remedy. All of the OU specific actions currently being undertaken in the San
Gabriel Valley are interim actions. It is anticipated that a final ROD will be issued for the
entire San Gabriel Valley Superfund site once RD/RA work has been completed at all of the
separate OUs.
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5 Highlights of Community Participation
The Proposed Plan for this remedy, in the form of a fact sheet, was distributed to the parties
on EPA's mailing list for the PVOU. The Proposed Plan, together with the Puente Valley
Operable Unit Interim Remedial Investigation (RI) (COM, 1997) and Feasibility Study (FS)
(EPA, 1997), were also made available at EPA's Regional Office in San Francisco, and locally
at three information repositories: the Hacienda Heights Public Library, the West Covina
Library, and the Rosemead Library. The Administrative Record for the PVOU was placed
in CD-ROM format in each repository, and the RI/FS was available on microfilm at each
repository.
EPA held a public meeting to present the Proposed Plan and EPA's preferred alternative on
January 28,1998, at the La Puente High School in LaPuente, California. Notice of EPA's
public meetings, availability of the Proposed Plan, and the announcement of a 30-day public
comment period were published in the following newspapers:
Los Angeles Times, San Gabriel Valley Edition January 16,1998
San Gabriel Valley Tribune January 16,1998
EPA extended the public comment period in response to requests from members of the
public. EPA prepared a fact sheet announcing the extension of the public comment period
and distributed it to the parties on EPA's mailing list for the PVOU. The total public
comment period was 60 days and ran from January 15 to March 16,1998. EPA received
several sets of written comments during the public comment period. These comments are
addressed in the Responsiveness Summary, included as Part n of this ROD (contained in
Volume 2).
This decision document presents the selected remedial action for the ROD site and has been
chosen in accordance with CERCLA, as amended, and to the extent practicable, the National
Oil and Hazardous Substances Pollution Contingency Plan (NCP). The ROD is based on the
Administrative Record.
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6 Summary of Site Characteristics
The PVOU is part of the San Gabriel Valley Superfund Site located in eastern Los Angeles
County, California. Puente Valley is an approximately 12-1/2-mile-long and 2- to
2-1/2-mile-wide tributaiy basin to the Main San Gabriel Basin.
The majority of the PVOU is highly industrialized and is occupied by the City of Industry,
an incorporated city that covers approximately 11 square miles. Approximately 96 percent
of the city is zoned for industrial purposes; the rest is zoned for commercial purposes.
Nearly 85 percent of the land within the boundaries of the City of Industry has been
developed, and accommodates approximately 1,700 businesses. Future development plans
will likely be for industrial and commercial uses.
A small amount of land within the City of Industry is allotted for residential purposes and is
occupied by approximately 631 residents. The Cities of La Puente and Walnut also occupy
portions of the PVOU. These portions are zoned primarily for residential purposes and are
likely to remain residential.
The State of California considers all subsurface zones of relatively high permeability
(shallow, intermediate, and deep) in the PVOU to be municipal water sources. VOCs are
the primary organic contaminants found in the PVOU above EPA maximum contaminant
levels (MCLs). Tetrachloroethene (PCE) and trichloroethene (TCE) are the VOCs that have
been detected most often in ground water, although 1,1-dichloroethane, 1,1-dichloroethene,
1,2-dichloroethene, and 1,1,1-trichloroethane have also been detected above MCLs in the
PVOU. Figures 2 and 3 show 1997 VOC concentrations in the shallow and intermediate
zones.
Sources of the ground-water contamination include firms engaged in metal cleaning,
coating, and manufacturing; chemical product manufacturing; plastics; aerosols; electric
component manufacturing; printing; rubber manufacturing; die casting; and engineering.
To address these sources of ground-water contamination, the RVVQCB, under a grant from
EPA, oversees investigations and cleanups at facilities where releases have occurred. In
general, VOC concentrations are highest in the shallow ground water beneath facility source
areas where releases have occurred. VOCs have also spread to the intermediate zone and
portions of the deep zone primarily as a result of downward hydraulic gradients.
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7 Summary of Site Risks
In 1994, EPA completed a Preliminary Baseline Risk Assessment for the Puente Valley OU
(EPA, 1994). The purpose of the risk assessment was to evaluate potential adverse health
effects from exposure to contaminated ground water. The results of the risk assessment
assisted EPA to determine if any remedial actions would be necessary to protect human
health or the environment. The risk assessment process included: (a) identifying chemicals
present in ground water, (b) characterizing the population potentially exposed to these
contaminants, and (c) evaluating the potential health effects resulting from exposure to the
contaminated ground water. EPA has evaluated how individuals might be exposed to these
contaminants under both current and future conditions, and potential risks to natural
resources.
7.1 Identification of Chemicals of Potential Concern
Fifty-four VOCs detected in ground water from production and monitoring wells in the
PVOU were included in the risk assessment as chemicals of potential concern (COPCs) in
ground water. Eight VOCs detected in surface water samples were included in the risk
assessment as COPCs in surface water. (See Tables 2 and 3 in the Puente Valley Operable
Unit Preliminary Baseline Risk Assessment prepared by CH2M HILL for the EPA, March 1,
1994.) Table 1 summarizes the COPCs in ground water used in the baseline risk assessment,
and their respective applicable or relevant and appropriate requirements (ARARs).
7.2 Exposure Assessment
Exposure assessment is the determination or estimation of the magnitude, frequency,
duration, and route of exposure. This section briefly summarizes the potentially exposed
populations, the exposure pathways evaluated, and the exposure quantification from the
risk assessment performed for the PVOU.
Land use in the PVOU includes primarily commercial/industrial and residential. Ground
water from five of the seven production wells sampled in 1991 and 1992 is currently being
used for domestic purposes. Exposure to contaminants in ground water could occur
through the use of ground water for domestic purposes, such as ingestion of water used for
drinking and cooking. Residents and workers could also be exposed to contaminants in
ground water through the transport of VOCs from ground water through soil and into
ambient air or through the foundation of a building. EPA evaluated three scenarios in the
risk assessment for the PVOU in which individuals might be exposed to the contaminated
ground water:
1. Potential for a current resident to be exposed to contamination in ground water through
domestic use
2. Potential for a future resident to be exposed to contamination in ground water through
domestic use
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7 SUMMARY OF SfTE RISKS
3. Potential for current and future workers and residents to be exposed to contamination in
ground water through transport of VOCs from ground water through the foundation of
a building
EPA evaluates potential exposure to contaminated ground water in the absence of
regulatory controls, such as the Safe Drinking Water Act, which is designed to prevent
delivery of water for potable use if contaminant concentrations exceed MCLs. Based on
potential for exposure frequency, duration, and estimated intake, residents exposed to
contaminated ground water used for domestic purposes are expected to be the maximally
exposed population.
7.3 Toxicity Assessment
Table 1 shows the COPCs for the PVOU. One of the compounds, vinyl chloride, is a known
human carcinogen (EPA weight of evidence class A); four of the compounds
(tetrachloroethene, trichloroethene, 1,2-dichloroethane, and methylene chloride) are
probable human carcinogens (EPA weight of evidence class B2); and three of the
compounds (1,4-dichlorobenzene, 1,1,-dichloroethene, and 1,1,2-trichloroethane) are
possible human carcinogens (EPA weight of evidence class C). Based on data from various
animal studies, the oral carcinogenic slope factors for these compounds are:
Vinyl Chloride -1.9 (mg/kg/day)-1 (Source: Health Effects Assessment Summary Tables
(HEAST), EPA, 1992a).
Tetrachloroethene - 0.051 (mg/kg/day)-1 (Source: Environmental Criteria and Assessment
Office, EPA, 1993b).
Trichloroethene - 0.011 (mg/kg/day)-1 (Source: Health Effects Assessment Summary
Tables, EPA, 1992a).
1,2-Dichloroethane - 0.091 (mg/kg/day)-1 (Source: Integrated Risk Information System
(IRIS), EPA, 1993a).
Methylene Chloride - 0.0075 (mg/kg/day)-1 (Source: Integrated Risk Information System
(IRIS), EPA, 1993a).
1,4-Dichlorobenzene - 0.024 (mg/kg/day)-1 (Source: Health Effects Assessment Summary
Tables, EPA, 1992a).
1,1,2-Trichloroethane - 0.057 (mg/kg/day)-1 (Source: Integrated Risk Information System
(IRIS), EPA, 1993a).
With the exception of 1,4-dichlorobenzene, all of the above compounds are also considered
carcinogenic through the inhalation route. Based on data from various animal studies, the
inhalation carcinogenic slope factors are:
Vinyl Chloride - 0.3 (mg/kg/day)-1 (Source: Health Effects Assessment Summary Tables,
EPA, 1992a).
Tetrachloroethene - 0.002 (mg/kg/day)-1 (Source: Environmental Criteria and Assessment
Office, EPA, 1993b).
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7 SUMMARY OF SHE RISKS
Trichloroethene - 0.006 (mg/kg/day)-1 (Source: Environmental Criteria and Assessment
Office, EPA, 1993b).
1,2-Dichloroethane - 0.091 (mg/kg/day)-1 (Source: Integrated Risk Information System
(IRIS), EPA, 1993a).
Methylene Chloride - 0.002 (mg/kg/day)-1 (Source: Integrated Risk Information System
(IRIS), EPA, 1993a).
1,1,2-Trichloroethane - 0.056 (mg/kg/day)-1 (Source: Integrated Risk Information System
(IRIS), EPA, 1993a).
At this time, slope factors are not available for the dermal route of exposure. The
preliminary risk assessment did not quantitatively estimate dermal absorption from
household water use because of the uncertainty associated with making a quantitative
estimate of such exposure.
In addition to their classification as carcinogens, five of the carcinogenic COPCs have
toxicity data indicating their potential for adverse noncarcinogenic effects in humans. The
chronic toxicity data available for these compounds have been used to develop oral
reference doses (RfDs). The oral RfDs for these compounds are:
Tetrachloroethene - 0.01 (mg/kg/day) (Source: Integrated Risk Information System (IRIS),
EPA, 1993a).
Trichloroethene - 0.006 (mg/kg/day) (Source: Environmental Criteria and Assessment
Office, EPA, 1993b).
Methylene Chloride - 0.06 (mg/kg/day) (Source: Integrated Risk Information System (IRIS),
EPA, 1993a).
1,1,2-Trichloroethane - 0.004 (mg/kg/day) (Source: Integrated Risk Information System
(IRIS), EPA, 1993a).
1,4-dichlorobenzene is also considered to have noncarcinognic effects via inhalation. The
inhalation reference dose for 1,4-dichlorobenzene is 0.2 milligrams per kilogram per day
(mg/kg/day) (HEAST).
Chronic toxicity testing has also established that 1,1-dichloroethene, 1,2-dichloroethene,
1,1,1-trichloroethane, and 2-propanone have noncancer endpoints that primarily affect the
liver. The oral RfDs for these compounds are:
1,1-Dichloroethene -0.009 (mg/kg/day) (Source: Integrated Risk Information System
(IRIS), EPA, 1993a).
1,2-Dichloroethene - 0.009 (mg/kg/day) (Source: Health Effects Assessment Summary
Tables, EPA, 1992).
1,1,1-Trichloroethane -0.09 (mg/kg/day) (Source: Health Effects Assessment Summary
Tables, EPA, 1992).
2-Propanone - 0.10 (mg/kg/day) (Source: Integrated Risk Information System (IRIS), EPA,
1993a).
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7 SUMMARY OF SITE RISKS
7.4 Risk Characterization Summary
This section presents the results of the evaluation of the potential risks to human health
associated with exposure to contaminated ground water at the PVOU. Exposure scenarios
are evaluated by estimating the noncartinogenic and carcinogenic risks associated with
them.
The potential for carcinogenic effects is evaluated by estimating the excess lifetime cancer
risk, which is the probability of developing cancer during one's lifetime over the
background probability of developing cancer (i.e., if no exposure to site contaminants
occurred). These risks are probabilities that usually are expressed in scientific notation (e.g.,
1 x 10*). An excess lifetime cancer risk of 1 x 10* indicates that an individual has a 1 in
1,000,000 chance of developing cancer as a result of site-related exposure. EPA uses an
excess lifetime cancer risk of 1 x 10* as an acceptable incremental cancer risk above
background, and an excess lifetime cancer risk of one in ten thousand (1 x 10^) as the point
at which action is generally warranted at a site (EPA, 1991c), thus creating EPA's generally
acceptable risk range of 1 x 10-* to 1 x 10*.
Noncarcinogenic risk is assessed by comparing the estimated daily intake of a chemical to
its RfD. An RfD represents a level that an individual may be exposed to without any
adverse effects. The comparison is expressed as a hazard quotient (HQ). An HQ less than
one indicates that noncarcinogenic effects from exposure to that chemical are unlikely. HQs
for all chemicals of concern that affect the same target organ are added to generate the
Hazard Index (HI). An HI less than one indicates that noncarcinogenic effects from all the
contaminants are unlikely. Conversely, an HI greater than one indicates that site-related
exposures may present a risk to human health.
The results of the baseline risk assessment indicate that the potential for a future resident to
be exposed to ground-water contamination through domestic use resulted in a total
estimated incremental lifetime cancer risk greater than one person in one thousand (1 x 10'3).
This risk exceeds the acceptable risk range and therefore indicates action at the site is
warranted.
Exposure of Residents to Ground Water Through Domestic Use. Tables 2 and 3 present
the Estimated Noncancer Hazard Index and Total Excess Lifetime Cancer Risk,
respectively, from domestic use of ground water. To assess potential current residential
exposure to ground water through domestic use, all active production wells sampled in
1991 and 1992 that had detections for VOCs were evaluated. These wells include
production wells 08000077, 98000068, and 98000108. The estimated HI is less than one for
both the average and Reasonable Maximum Exposure (RME) scenarios for these three
production wells. The estimated excess lifetime cancer risk for both the average and RME
exposure scenarios are below or within EPA's 1 x 10"4 to 1 x 10* acceptable risk range.
To assess potential future exposure to contamination in ground water through domestic use,
the preliminary risk assessment focused on the eight areas within the PVOU that have
ground-water concentrations exceeding 10 times the MCLs. Potential future residential
exposures were evaluated based on well groups sampled in 1991 and 1992 within the eight
areas. The estimated hazard index for the average ingestion and inhalation exposure
scenario ranges from 0.4 in well group 8 to 40 for ingestion and 30 for inhalation in well
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7 SUMMARY Of SITE RISKS
group 3. The RME ingestion and inhalation exposure scenario ranges from 0.5 in well
group 8 to 60 in well group 3. Both average and RME exposure scenarios exceed the hazard
index of 1 (and hazard quotient of 1) for well groups 3 and 5, suggesting that exposure may
present a risk to human health.
The estimated excess lifetime cancer risk for the average exposure scenario exceeds EPA's
acceptable risk range in well groups 3,4, and 5. The estimated excess lifetime cancer risk for
the average ingestion exposure scenario ranges from 4 x 10-6 in well group 1 to 4 x 10-* in
well group 5. For the average inhalation scenario, the estimated excess lifetime cancer risk
ranges from 7 x 1Q-7 in well group 1 to 2 x 10-* in well group 5.
The RME exposure scenarios exceeded EPA's acceptable risk range for well groups 2, 3, 4,5,
6, and 7. The RME ingestion scenario excess cancer risk ranged from 1 x 10's in well group 1
to 3 x 10'3 in well group 5. RME inhalation risks ranged from 2 x 10-* in well group 1 to
2 x 10'3 in well group 5.
Additionally, exposure to 1,1-dichloroethene in ground water was evaluated using the
modified RfD/cancer ratio approach that EPA Regional IX and the Office of Drinking Water
recommend. The modified RfD approach is recommended on a chemical-by-chemical basis
for certain group C chemicals (e.g., 1,1-dichloroethene) that have limited evidence of
carcinogenicity. Because of this limited evidence, the modified RfD approach utilizes the
risk assessment protocols for compounds with noncancer effects, but modifies the protocol
by adding a safety factor of 10 to be health-protective. Using the modified RfD approach, the
estimated ratio for potential current residential exposures ranges from 0.2 to 2. These
estimates are health-protective because they do not consider treatment or blending of
contaminated water with clean water, and incorporate a safety factor. For potential future
residential exposure to 1,1-dichloroethene in ground water, the cancer ratio is greater than
one for all well groups except well groups 4 and 6. Although ratios greater than 1 suggest
possible cancer concerns, there is very limited evidence that this contaminant is carcinogenic
in humans or animals.
Exposure of Workers arid Residents to Contaminants in Ground Water Through the
Transport of VOCs from Ground Water Through the Foundation of a Building. A
screening assessment was used to quantitatively evaluate potential risk to current workers
and futures workers and residents as a result of exposure to contaminants in ground water
through the transport of VOCs from ground water through the foundation of a building.
Five chemicals were evaluated in this assessment: 1,2-dichloroethane, 1,1-dichloroethene,
methylene chloride, tetrachloroethene, and trichloroethene. The estimated hazard quotient
was less than one for both the residential and worker exposure scenarios. The estimated
excess lifetime cancer risk was below or within EPA's acceptable risk range.
Exposure of Vegetation and Wildlife to Contaminants in Surface Water. Eight VOCs were
detected in surface water in the San Jose Creek. Potential environmental receptors include
vegetation and wildlife exposed to surface water in this area. The detected VOCs will be
removed from water primarily by volatilization to the atmosphere. These VOCs are not
expected to significantly bioconcentrate in aquatic organisms or adsorb to sediment. A
comparison of concentrations detected in surface water to the corresponding chemical-
specific acute and chronic Ambient Water Quality Criteria shows that the criteria are
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7 SUMMARY OF Slit RISKS
considerably higher than the detected concentrations. Therefore, no adverse impact to
aquatic organisms is predicted.
Based on this risk characterization summary, actual or threatened releases of hazardous
substances at this site, if not addressed by the preferred alternative or one of the other active
measures considered, may present a current or potential threat to public health, welfare, or
the environment.
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8 Description of Remedial Alternatives
EPA's Remedial Action Objectives (RAOs) for the PVOU are to:
Prevent exposure of the public to contaminated ground water
Inhibit contaminant migration from the more highly contaminated portions of the
aquifer to the less contaminated areas or depths
Reduce the impact of continued contaminant migration on downgradient water supply
wells
Protect future uses of less contaminated and uncontaminated areas
The RAOs reflect EPA's regulatory goal of restoring usable ground waters to their beneficial
uses wherever practicable, within a time frame that is reasonable; or, if restoration is
deemed impracticable, to prevent further migration of the plume, prevent exposure to the
contaminated ground water, and evaluate further risk reduction (40 CFR
Section 300.430(a)(l)(iii)(F)).
The RAOs for the PVOU do not include numeric, chemical-specific objectives in the aquifer
or a time frame for restoration because this is an interim action. They do include VOC
"mass removal" as a secondary objective. EPA's selected alternative will remove significant
contaminant mass from trie aquifer, in effect beginning the restoration process, but it will be
designed for migration control rather than mass removal.
Four alternatives were evaluated in the FS for the PVOU:
Alternative 1 - No Action
Alternative 2 - Ground-water Monitoring
Alternative 3 - Ground-water Control in the Shallow and Intermediate Zones at the
Mouth of the Valley
Alternative 4 - Ground-water Control in the Shallow and Intermediate Zones at the
Mouth of the Valley and in the Intermediate Zone at Mid-Valley
A brief description of each of the four remedial alternatives is presented below.
8.1 Alternative 1 No Action
The NCP requires a no-action alternative to provide a baseline for comparison to other
alternatives. In this no-action alternative, no remedial actions are taken to control migration
from or within the Puente Valley area. This alternative does not include any ground-water
monitoring, extraction, or treatment, nor does it consider other ongoing activities that are
not part of a CERCLA remedy that may or may not continue into the future. Ground-water
SCQ/982660003.DOC/3-97 8-1
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8 DESCRIPTION OF REMEDIAL ALTERNATIVES
extraction at water supply wells is considered as part of background conditions in the
PVOU area and, therefore, would continue to occur under Alternative 1.
8.2 Alternative 2 - Ground-water Monitoring
The only remedial action incorporated into Alternative 2 is ground-water monitoring to
monitor compliance with RAOs and performance criteria in the shallow, intermediate, and
deep zones at mid-valley and the mouth of the valley. Alternative 2 does not have any
extraction, treatment, conveyance, or discharge components (other than the same
background pumping considered in Alternative 1) and, therefore, does not address
contaminant migration.
Monitoring
For cost estimation and evaluation of the alternative, it was assumed that 16 new
monitoring wells would be installed: 4 new wells downgradient of mid-valley in the
intermediate and deep zones, and 12 new wells near the mouth of the valley in the shallow
and intermediate zones.
8.3 Alternative 3 - Ground-water Control in the Shallow and
Intermediate Zones at the Mouth of the Valley
Alternative 3 is containment of contaminated ground water in the shallow and intermediate
zones at the mouth of the valley. For the purposes of cost estimation and evaluation,
extraction and treatment systems were assumed to be implemented, though the actual
remedy may differ. The remedy implemented will need to meet the performance criteria
specified in Section 10 this ROD. Components of this alternative are as follows.
Extraction
The ground-water extraction in Alternative 3 includes four wells in each zone (shallow and
intermediate). The total extraction rates from the shallow and intermediate zones are
700 and 1,000 gallons per minute (gpm), respectively, for a total flow of 1,700 gpm. The
actual extraction well locations and rates will be determined during remedial design based
on additional evaluation of the extent of contamination during the remedial design
investigation.
Treatment
Extracted ground water will be treated by either air stripping with offgas treatment or
liquid-phase carbon adsorption to remove VOCs prior to discharge. For cost estimation
purposes, this alternative assumes a treatment system using air stripping with adsorption of
VOCs in offgas. Construction of a single 1,700-gpm, centralized treatment plant near the
mouth extraction system is assumed for this alternative.
If water is discharged to a municipal water supply system, treatment to reduce
concentrations of total dissolved solids (TDS) and nitrate would probably be required for
shallow ground water. The assumed level of treatment for inorganic constituents, if
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6 DESCRIPTION Of REMEDIAL ALTERNATIVES
required, would be to the MCL or secondary drinking water standard, as applicable. In the
FS, a membrane separation process was assumed for discharge to a municipal water supply
system.
Conveyance
Treated ground water may be discharged to Puente Creek or other surface waters or
provided to a municipal supply system. Preliminary evaluations that PVSC conducted
indicate that there are nearby water distribution systems operated by San Gabriel Valley
Water Company, Suburban Water Systems, and the City of Industry. These purveyors have
indicated that the water demands for any of these nearby systems substantially exceed the
ground-water extraction rate assumed for this alternative.
Discharge
As described above, treated water may be either discharged to surface waters or to a water
. supply line for municipal use.
Monitoring
Alternative 3 also includes a monitoring system to ensure compliance with RAOs and
performance criteria in the shallow, intermediate, and deep zones at mid-valley and the
mouth of the valley. In addition, selected monitoring wells may provide an early warning
system for extraction and treatment systems. A total of 12 new wells was assumed: 4 new
wells downgradient of mid-valley in the intermediate and deep zones, and 8 new wells near
the mouth of the valley in the shallow and intermediate zones. Implementation of this
monitoring program during the initial stages of the remedial design will help to define
design parameters.
8.4 Alternative 4 Ground-water Control in the Shallow and
Intermediate Zones at the Mouth of the Valley and in the
Intermediate Zone at Mid-Valley
Alternative 4 includes all of the components described for Alternative 3, plus ground-water
extraction and treatment components in the intermediate zone at mid-valley. The
additional extraction is intended to address migration of contamination in the intermediate
zones. The remedial action components described below have been defined only for the
purposes of cost estimation and evaluation. If Alternative 4 is selected, the actual remedy
implemented will need to meet the performance criteria identified in this ROD, and could
therefore have different components than those assumed for the FS.
Extraction
As stated above, Alternative 4 includes the same mouth of the valley pumping system as
described for Alternative 3. Installation of four extraction wells (screened from 200 to
250 feet below ground surface (bgs) has been assumed along the west side of Hacienda
Boulevard, with one well south of San Jose Creek and three wells north of the creek. Three
of the wells have an extraction rate of 150 gpm each. The fourth well provides an extraction
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8 DESCRIPTION OF REMEDIAL ALTERNATIVES
rate of 100 gpm, yielding a total extraction rate of 550 gpm from the intermediate zone at
mid-valley.
Treatment
Alternative 4 includes the same treatment processes and mouth of the valley treatment plant
described for Alternative 3. Alternative 4 assumes that a separate, 550-gpm, mid-valley
treatment plant will be built to treat ground water extracted from the mid-valley system. If
it appears to be more cost-effective, a single treatment plant system could be designed to
treat water extracted from both the mouth of the valley and mid-valley systems. If
discharge to San Jose Creek is selected as the discharge option, a treatment plant located
closer to San Jose Creek would reduce treated water conveyance costs.
Conveyance
The conveyance system includes untreated water pipelines from the extraction wells to the
treatment plant and treated water pipeline alignments to the San Jose Creek and potential
connection points to municipal water supply system lines. Several potential connection
points to water supply systems exist in the treatment plant vicinity. Suburban Water
Systems has a 16-inch-diameter pipeline adjacent to Hacienda Boulevard. The City of
Industry operates a 16-inch-diameter pipeline adjacent to Valley Boulevard. The San
Gabriel Valley Water Company operates a 14-inch pipeline that extends along the south side
of San Jose Creek, and also has a 12-inch-diameter pipeline along Valley Boulevard west of
Proctor Avenue. Discharge to nearby San Jose Creek is also an option.
Discharge
As discussed above, water may be either discharged to surface waters or to a water supply
line for municipal use.
Monitoring
Alternative 4 includes the monitoring system to monitor compliance with RAOs and
performance criteria in the shallow, intermediate, and deep zones at mid-valley and the
mouth of the valley. A total of 13 new wells is assumed: 5 new wells in the mid-valley area
(intermediate and deep zones) and 8 new wells near the mouth of the valley (shallow and
intermediate zones). Implementation of this monitoring program during the initial stages of
the remedial design will help to define design parameters.
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9 Summary of Comparative Analysis of
Alternatives
The four remedial alternatives described in Section 8 are compared to the Superhind nine
evaluation criteria listed in 40 CFR Section 300.430. The comparative analysis provides the
basis for determining which alternative presents the best balance of the criteria. The first
two evaluation criteria are considered threshold criteria that the selected remedial action must
meet. The five primary balancing criteria are balanced to achieve the best overall solution.
The two modifying criteria, state and community acceptance, are also considered in remedy
selection.
Threshold Criteria
Overall Protection of Human Health and the Environment addresses whether each
alternative provides adequate protection of human health and the environment, and
describes how risks posed through each exposure pathway are eliminated, reduced, or
controlled through treatment, engineering controls, and/or institutional controls.
Compliance with ARARs addresses the requirement of Section 121(d) of CERCLA that
remedial actions at least attain legally applicable or relevant and appropriate federal and
state requirements, standards, criteria, and limitations, which are collectively referred to
as "ARARs," unless such ARARs are waived under CERCLA Section 121(d)(4).
Primary Balancing Criteria
Long-term Effectiveness and Permanence refers to the ability of a remedy to maintain
reliable protection of human health and the environment over time.
Reduction of Toxicity, Mobility, or Volume Through Treatment refers to the
anticipated performance of the treatment technologies that may be included as part of a
remedy.
Short-term Effectiveness addresses the period of time needed to implement the remedy
and any adverse impacts that may be posed to workers and the community during
construction and operation of the remedy until cleanup goals are achieved.
Implementability addresses the technical and administrative feasibility of a remedy
from design through construction and operation. Factors such as availability of services
and materials, administrative feasibility, and coordination with other governmental
entities are also considered.
Cost evaluates the estimated capital, operation and maintenance (O&M), and indirect
costs of each alternative in comparison to other equally protective alternatives.
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9 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
Modifying Criteria
State Acceptance indicates whether the state agrees with, opposes, or has concerns
about the preferred alternative.
Community Acceptance includes determining which components of the alternatives
interested persons in the community support, have reservations about, or oppose.
This section describes each threshold and primary balancing criterion, evaluates each
alternative in relation to each criterion, and identifies advantages and disadvantages among
the alternatives in relation to each criterion. Figure 4 presents a comparative matrix in
which the four alternatives are ranked for each of the evaluation criterion. The details of
how the rankings have been assigned for each criterion are provided below.
9.1 Overall Protection of Human Health and the Environment
The NCP requires that all alternatives be assessed to determine whether they can
adequately protect human health and the environment from unacceptable risks from site
contamination. These risks can be mitigated by eliminating, reducing, or controlling
exposure to hazardous substances, pollutants, or contaminants.
9.1.1 Overall Protection of Human Health and the Environment: Evaluation of
Alternatives
Alternatives 1 and 2 do not provide protection of human health and the environment.
These two alternatives allow migration of VOC contamination to continue. Alternative 2
would include ground-water monitoring to provide early warning of expected increases in
contaminant concentrations that may interfere with the ability of area water purveyors to
supply ground water meeting MCLs.
Alternatives 3 and 4 provide protection of human health and the environment by inhibiting
contaminant migration, thereby protecting future uses of less contaminated and
uncontaminated ground water. Alternatives 3 and 4 would also reduce the toxicity,
mobility, and volume of the contaminants and remove significant contaminant mass from
the aquifer. Alternative 4 includes additional extraction in the mid-valley intermediate zone
that is not assumed in Alternative 3. This extraction would provide additional protection
for the intermediate and deep zone downgradient of mid-valley and remove additional
contaminant mass.
Alternatives 1 and 2 are assigned low rankings in Figure 4 because they fail to provide
migration control. Alternatives 3 and 4 are assigned high rankings because they meet this
threshold requirement of protecting human health and the environment. Alternative 4 is
ranked slightly higher than Alternative 3 because of the additional migration control and
mass removal at mid-valley.
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9 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
9.2 Compliance with ARARs
This evaluation criterion is also a threshold requirement and is used to determine if each
alternative would attain federal and state ARARs, or whether there is adequate justification
for invoking waivers for specific ARARs.
9.2.1 Compliance with ARARs: Evaluation of Alternatives
Alternatives 1 and 2 do not meet ARARs. Both alternatives allow for continued
uncontrolled migration of contaminants, at levels exceeding MCLs, into production wells
located at the mouth of Puente Valley. Neither alternative ensures that water produced
from these wells will meet drinking water ARARs. The continued migration of
contaminants under Alternatives 1 and 2 would not meet the chemical-specific ARARs
established for the uncontaminated ground water in the intermediate zone.
Alternatives 3 and 4 meet the ARARs described in Section 11 of this ROD. Both of the
retained treatment technologies are technically capable of meeting ARARs for VOCs in the
extracted ground water. Since this is an interim remedial action to contain contamination,
EPA has not established chemical-specific ARARs for the contaminated portions of the
aquifer.
Alternatives 1 and 2 are assigned low rankings because they do not meet this threshold
requirement of complying with ARARs. Alternatives 3 and 4 are assigned high rankings
because they do comply with ARARs. There are no significant differences in the ability of
Alternatives 3 and 4 to comply with ARARs.
9.3 Long-Term Effectiveness
This evaluation criterion assesses the extent to which each remedial alternative reduces risk
after the remedial action objectives are met. Residual risk can result from exposure to
untreated waste or treatment residuals. The magnitude of the risk depends on the
magnitude of the wastes and the adequacy and reliability of controls, if any, that are used to
manage untreated waste and treatment residuals. For this interim action, untreated waste
refers to any contaminated ground water not removed from the aquifer.
The performance of the alternatives in relation to this criterion is evaluated primarily by
estimating the extent to which each alternative prevents the migration of contamination into
less contaminated and uncontaminated areas. Preventing or reducing contaminant
migration reduces contaminant concentrations in downgradient areas, reducing risk by
reducing the likelihood of exposure. Performance was evaluated using ground-water
modelling. Because this is an interim remedy to contain contaminant migration, untreated
wastes will remain in the ground water.
9.3.1 Long-Term Effectiveness and Permanence: Evaluation of Alternatives
Ground-water modelling results presented in the FS suggest Alternatives 1 and 2 do not
contain contaminant migration in either the shallow or intermediate zones in the PVOU.
Alternatives 3 and 4 are effective at containing migration of contamination at the mouth of
the valley in the shallow and intermediate zones. Modelling results indicate that only
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9 SUMMARY Of COMPARATIVE ANALYSIS OF ALTERNATIVES
Alternative 4 is effective at containing intermediate zone migration at mid-valley, although
Alternative 3 provides a measure of protection by containing contamination in the
intermediate zone at the mouth of the valley.
Alternatives 1 and 2 do not prevent contaminant migration in either the shallow or the
intermediate zones and, therefore, are assigned a low ranking in Figure 4 because they do
not provide significant long-term effectiveness and permanence. Alternatives 3 and 4 are
assigned a high ranking because they do contain contaminant migration. Alternative 4 is
ranked slightly higher than Alternative 3 because of the additional contaminant migration
control provided at mid-valley.
9.4 Reduction of Toxicity, Mobility, and Volume Through
Treatment
This criterion addresses the preference, as stated in the NCP, for selecting remedial actions
employing treatment technologies that permanently and significantly reduce toxicity,
mobility, or volume of the hazardous substances as a principal element of the action. This
preference is satisfied when treatment is used to reduce the principal threats at a site
through destruction of toxic contaminants, reduction of total mass of toxic contaminants,
irreversible reduction in contaminant mobility, or reduction of total volume of contaminated
media.
This evaluation focuses on the following factors for each remedial alternative:
Whether the alternative satisfies the statutory preference for treatment as a principal
element
The treatment process employed, including the amount of hazardous materials that will
be destroyed or treated and the degree of expected reduction in toxicity, mobility, or
volume
The degree to which treatment is irreversible
The type and quantity of treatment residuals that will remain following treatment
9.4.1 Reduction of Toxicity, Mobility, or Volume Through Treatment: Evaluation
of Alternatives
Alternatives 1 and 2 do not provide any reduction in toxicity, mobility, or volume and do
not satisfy the statutory preference for treatment. Alternatives 3 and 4 satisfy the statutory
preference for treatment. Both of these alternatives would significantly reduce the volume
and mobility of contamination by inhibiting further contaminant migration. The two
treatment technologies retained for Alternatives 3 and 4, air stripping with offgas controls
and liquid-phase carbon adsorption, would irreversibly reduce the toxicity and volume of
contaminants in the extracted ground water and result in an effluent stream that meets
drinking water standards for VOCs. Both treatment technologies would result in the
destruction of VOCs if the granular activated carbon is regenerated. These technologies
would create residuals if used carbon is not regenerated.
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9 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
Alternative 3 is estimated to provide removal of 15,200 pounds of VOCs over a 30-year
period of operation. Alternative 4 is estimated to provide removal of 25,000 pounds of
VOCs over a 30-year period of operation. The increase in mass removal for Alternative 4
over Alternative 3 is estimated to be 9,800 pounds. The actual operation of the extraction
and treatment systems in Alternatives 3 and 4 could yield lower or higher values.
Alternatives 1 and 2 are assigned a low ranking in Figure 4 because they do not satisfy the
statutory preference for treatment and do not reduce the toxicity, mobility, or volume of
contaminants. Alternatives 3 and 4 are assigned a high ranking because they do satisfy the
statutory preference for treatment and significantly reduce the toxicity, mobility, and
volume of contaminants by inhibiting contaminant migration and producing an effluent
stream that meets MCLs. Alternative 4 is ranked slightly higher because of the additional
contaminant migration control and mass removal in the mid-valley area incorporated into
this alternative.
9.5 Short-Term Effectiveness
This criterion evaluates the effects of each remedial alternative on human health and the
environment during the construction and implementation phase until remedial action
objectives are met. The following factors are addressed for each alternative:
Protection of workers and the community during construction and implementation
phases. This factor qualitatively examines risk that results from implementation of the
proposed remedial action and the effectiveness and reliability of protective measures.
Environmental impacts. This factor addresses the potential adverse environmental
impacts that may result from the construction and implementation of an alternative.
This factor also evaluates the reliability of the available mitigation measures to prevent
or reduce potential impacts.
Time until RAOs are achieved.
9.5.1 Short-Term Effectiveness: Evaluation of Alternatives
Alternative 1 is not evaluated for this criterion because there is no construction or
implementation phase. None of the alternatives pose immitigable risks to the community
during construction and implementation. Nor do any of the alternatives pose unmitigable
risks to workers beyond general construction hazards associated with large construction
projects. No unmitigable negative environmental impacts are anticipated in the areas in
which facilities would be constructed.
For Alternative 2, the RAOs would not be met as long as contaminant migration continues.
Additional investigation is required to assess the current magnitude of contaminant
migration in portions of the PVOU area. However, the modelling for Alternatives 1 and 2
suggests that contaminant migration is likely to continue for a considerable length of time.
The RAOs would be met for Alternatives 3 and 4 as soon as the ground-water extraction
and treatment components begin operation.
The time until RAOs are achieved (i.e., system startup) for Alternatives 3 and 4 is
anticipated to be within approximately 3 to 5 years. However, there are several
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9 SUMMARY OF COMPARATIVE ANALVSIS OF ALTERNATIVES
implementability issues (described in Section 9.6) that could impact this time. In addition,
implementation of these alternatives could be complicated by the need to obtain sites for
remedy components (wells and treatment facilities) and the need to construct conveyance
systems in heavily developed areas. Ground-water treatment may create hazardous waste
residuals (e.g., spent carbon).
Alternatives 3 and 4 are assigned a high ranking because there are no immitigable risks to
the community, workers, or the environment during construction and implementation.
There are no significant differences between the two alternatives, although Alternative 4
will likely take slightly longer to meet RAOs because of the additional construction at
mid-valley. Although there are no immitigable risks associated with construction and
implementation of Alternative 2 and there is less overall construction, Alternative 2 is
assigned a medium ranking because RAOs are never achieved.
9.6 Implementablity
This criterion addresses the technical and administrative feasibility of implementing an
alternative and the availability of various services and materials required during its
implementation. The following factors are considered:
Technical Feasibility
- Ability to construct and operate: addresses any technical difficulties and unknowns
associated with construction or operation of the technology
- Reliability of technology: focuses on the likelihood that technical problems
associated with implementation will lead to schedule delays
- Ease of undertaking additional remedial action: includes a discussion of what, if
any, future remedial actions may need to be undertaken and how the remedial
action would interfere with, or facilitate, the implementation of future actions
Administrative Feasibility
- Coordination with other agencies, including the need for agreements with parties
other than EPA required for construction and operation of the remedy
Availability of Services and Materials
- Availability of necessary equipment, specialists, and provisions to assure any
necessary resources
- Availability of services and materials, plus the potential for obtaining competitive
bids
9.6.1 Implementability: Evaluation of Alternatives
Alternative 1 is not evaluated for this criterion because no action is implemented. As
described above, the implementability evaluation incorporates several factors. Each of these
is discussed separately in the following text.
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9 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
Technical Feasibility: Ability to Construct and Operate. The extraction, treatment, and
conveyance technologies included in Alternatives 3 and 4 and the monitoring technologies
included in all three remedial action alternatives are widely used. No significant difficulties
are expected in construction and operation of these technologies.
Technical Feasibility: Reliability of Technology. The extraction, treatment, conveyance,
and monitoring technologies in Alternatives 2,3, and 4 are generally known to be proven
and reliable.
Technical Feasibility: Ease of Undertaking Additional Remedial Actions. The
alternatives would not interfere with the implementation of future response actions to
further contain contamination or restore ground water in the PVOU area.
Administrative Feasibility. There are not likely to be any significant administrative
feasibility issues associated with implementation of Alternative 2, other than obtaining
access agreements for monitoring well installation. Implementation of Alternatives 3 and 4
would require acquisition of property and/or easements for the construction of extraction
wells, treatment facilities, and conveyance facilities.
In addition/ implementing Alternatives 3 or 4 would require resolution of the following
administrative issues associated with ground-water extraction and discharge of treated
water to local water purveyors or to the Puente Creek:
Agreements would need to be made with the Watermaster or with a water purveyor to
account for extraction from the basin by the parties implementing the selected remedy
because these parties do not have water rights.
Agreements would need to be reached with water purveyors that would receive treated
water from the ground-water treatment facilities specifying the amount of water each
purveyor would accept; the treated water delivery location; responsibility for any
necessary capital improvements to purveyor systems; and to determine operational,
liability, financial, and other arrangements.
Water purveyors would need to obtain approval for modifications to their water supply
permits.
Availability of Services arid Materials. Implementation of Alternatives 3 and 4 would
require fabrication of treatment plant equipment. Required services and materials are
believed to be available, including qualified contractors for construction and operation of
the necessary facilities.
Alternative 2 is assigned a high ranking in Figure 4 because there are no significant issues
that could impact implementability of this monitoring-only alternative. Alternatives 3 and 4
are assigned a medium ranking because of the administrative issues associated with
ground-water extraction and treated water discharge. Because the anticipated flow rates are
not high (less than 2,500 gpm), it is expected that these administrative issues will not result
in extensive delays in project implementation.
The technical feasibility of Alternatives 3 and 4 is similar, although the more complex
conveyance and treatment facilities required in Alternative 4 are more likely to lead to
schedule delays.
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9 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
9.7 Cost
This criterion addresses the total cost of each alternative. This includes short- and long-term
costs, and capital and O&M costs. The following cost elements are considered for each
alternative:
Capital Cost. Direct capital cost includes the cost of construction, labor, equipment,
land, site development, and service. Indirect capital cost includes engineering fees,
license and permit cost, startup and shakedown costs, and contingencies.
O&M Cost. Annual O&M cost includes operating labor cost, maintenance materials and
labor, pumping and treatment energy costs, monitoring costs, and all other
postconstruction costs necessary to ensure continuous effective operation of the
alternative.
Total Present Worth. The total present worth of each alternative is calculated at an
interest rate of 5 percent and a time period of 30 years. Total present worth for each
alternative includes capital cost plus the present worth of the annual O&M costs.
Cost per Pound of Mass Removed. The cost per pound of VOC mass removed is
calculated for each alternative that includes ground-water extraction and treatment.
The cost estimates are considered order-of-magnitude level estimates (i.e., the cost estimates
have an expected accuracy of +50 to -30 percent). The assumption of a 30-year operating
period is based on EPA guidance and does not reflect any specific finding regarding the
duration of the remedy.
9.7.1 Cost: Evaluation of Alternatives
Although there is no cost presented for the no-action alternative (Alternative 1), there have
been and would continue to be substantial financial impacts on local water purveyors or
their rate payers because of the continued migration of contamination to their production
wells. Table 4 summarizes the estimated costs for Alternatives 2 through 4, respectively.
9.7.2 Cost: Comparison of Alternatives
Table 4 compares the cost of each alternative for capital costs, long-term O&M costs, and
present worth. The short-term capital costs range from $2,344,000 for Alternative 2 to
$11,751,000 for Alternative 4. The annual O&M costs range from $360,000 for Alternative 2
to $1,634,000 for Alternative 4.
9.8 State Acceptance
The State of California has provided comments and feedback to EPA throughout the RI/FS
process for the PVOU. In a letter dated September 24,1998, the California Department of
Toxic Substance Control (DTSC), as lead agency for the state, concurred with EPA's selected
remedy. In addition, the RWQCB approved EPA's selected remedy at a meeting held on
September 14,1998.
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9 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
9.9 Community Acceptance
EPA received written comments from three individuals and several organizations or
agencies on the Proposed Plan for this interim action at the PVOU. In addition, EPA
received limited oral comments and questions at the public meeting held in January 1998 to
discuss EPA's plans. EPA responded directly to the oral questions and comments at the
public meeting. The entire transcript for the public meeting is included in the
Responsiveness Summary in Part n of this ROD (Volume 2). All of the written comments,
along with EPA's responses to them, are also presented in the Responsiveness Summary.
Several commenters expressed support for EPA's proposed remedy. Some commenters did
not believe that the remedy was necessary or supported by the information that has been
collected to date. EPA has determined that the preferred alternative presented in the
Proposed Plan represents the most appropriate remedy for the ROD site. None of the
comments received suggested a change to the overall remedy that EPA selected.
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10 Selected Remedy
After considering CERCLA's statutory requirements, the detailed comparison of the
alternatives using the nine criteria, and public comments, EPA, in consultation with the
State of California, has determined that the most appropriate remedy for this site is
Alternative 3: ground-water control in the shallow and intermediate zones at the mouth of
Puente Valley. This alternative meets the two NCP threshold evaluation criteria; overall
protection of human health and the environment and compliance with ARARs, and
provides the best balance of the remaining Superfund evaluation criteria. EPA expects that
this interim remedy will provide the basis for the final remedy for the PVOU.
Alternative 3 will be implemented using a performance-based approach. The performance-
based approach specifies criteria ("performance criteria") that must be met while allowing
flexibility in implementation. The performance criteria are designed to attain the RAOs for
the PVOU and are described below.
10.1 Performance Criteria
Performance Criterion for the Shallow Zone:
The remedial action shall prevent ground water in the shallow zone with VOC
contamination above 10 times the ARARs listed in Table Ifrom migrating beyond its
current lateral and vertical extent as described in the RI/FSfor the PVOU.
Compliance with this criterion will be monitored at wells described as follows:
Located laterally and vertically downgradient of contamination exceeding 10 times the
relevant ARAR, but within areas in which there is detectable VOC contamination in the
shallow zone
Completed with screen lengths generally of 20 feet or less between the water table and
150 feet bgs. Longer screened intervals may be appropriate in limited situations and
will be evaluated on a case-by-case basis
Extracted ground water will be treated by air stripping (with off-gas controls) or liquid-
phase carbon adsorption. If alternative treatment technologies are identified, EPA will
evaluate the alternative technologies in accordance with the criteria specified in 40 CFR
Section 300.430 during remedial design.
Performance Criterion for the Intermediate Zone
The remedial action shall provide sufficient hydraulic control to prevent ground water in
the intermediate zone with VOC contamination above ARARs listed in Table Ifrom
migrating beyond the B7 Well Field Area. The B7 Well Field Area is defined as the area
encompassed by (1) the wells listed in Table 5 and (2) the current downgradient extent of
contamination above ARARs in the intermediate zone, in the vicinity of the wells located
in Table 5.
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10 SELECTED REMEDY
Compliance with this criterion will be monitored at compliance wells described as follows:
Located within 2,000 feet or either (1) the current extent of ground water contaminated
with any VOC exceeding its ARAR or (2) a production well listed in Table 5, whichever
represents the nearest margin of the B7 Well Field Area
Located along the northern, northwestern, and western margins of the B7 Well Field
Area
Completed with screen lengths of 20 feet or less within the intermediate zone. Larger
screened intervals may be appropriate in limited situations and will be evaluated on a
case-by-case basis
Extracted ground water will be treated by air stripping (with off-gas controls) or liquid-
phase carbon adsorption. If alternative treatment technologies are identified, EPA will
evaluate the alternative in accordance with the criteria specified in 40 CFR
Section 300.430 during remedial design.
Implementation of the remedial action cannot result in any adverse effects (i.e., increases in
migration of contamination) to production wells that are not part of the remedial action. In
addition, the remedial action must provide adequate capture of contamination above
ARARs without relying on the effects of wells that are not part of the remedial action.
Compliance with Performance Criteria
Compliance with the performance criteria will be confirmed by quarterly sampling at
compliance wells. Over time, if it can be demonstrated, based on historical monitoring data,
that concentrations are unlikely to exceed the performance criteria in the short term,
monitoring intervals may be lengthened. If it appears, based on trends in monitoring data,
that concentrations may exceed the performance criteria, monitoring intervals may be
shortened.
Concentrations at compliance wells will be used as an absolute criterion to demonstrate
compliance. EPA expects that ground-water containment actions will be implemented
sufficiently upgradient of these wells to provide enough of a buffer zone to allow additional
actions to be taken, if necessary, to ensure compliance. EPA also anticipates that additional
monitoring wells will be installed, or existing wells within this buffer zone will be used to
provide an early warning system, and therefore provide sufficient time to address and
prevent noncompliance.
Imminent exceedence of the performance criteria at compliance wells indicates that ground-
water contamination is migrating, and hydraulic containment is required. Any actual or
imminent exceedence of the performance criteria at the compliance wells will require
ground-water extraction and treatment to achieve hydraulic containment. Actual
exceedence of performance criteria at compliance wells will result in the initiation of
enforcement actions.
Supplemental Explanation of Performance Criteria
The following paragraphs provide additional explanation of the performance criteria, their
meaning and objectives to help clarify the intent of the criteria.
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10 SELECTED REMEDY
The "Shallow" and "Intermediate" Zones
The shallow zone generally encompasses the upper 100 feet of the saturated aquifer,
including the interval between the water table and approximately 150 feet bgs. The
intermediate zone generally includes the relatively coarse-grained interval between the
shallow zone and deeper portions of the aquifer used for ground-water production. Both
terms are used in a manner consistent with their usage in the Puente Valley Feasibility
Study (EPA, 1997) and Remedial Investigation Report (COM, 1997).
The "shallow" and "intermediate" zones are terms intended to describe general horizons
within the aquifer(s) underlying the PVOU. During the course of the RI and development
of the FS, the complex stratigraphy was simplified with generalizing assumptions about
vertical intervals mat appear to have similar characteristics throughout the area. However,
actual subsurface conditions are not accurately described by terms that imply a well-layered
system. The alluvial materials that underlie the PVOU are very heterogeneous, and are
made up of interfingering lenses of variable hydraulic properties.
The shallow zone represents the upper portion of the saturated sediments at and under the
water table. Contaminant concentrations, transport rates, and aquifer materials in the
shallow zone are variable. Remediation of migrating contamination in the shallow zone
requires careful analysis of this variability, and an adequate understanding of the extent,
nature, and sources of contamination.
The intermediate zone is described as the "663" zone in portions of the RI and FS. This term
is based on a well (MW 6-63) completed in a zone of relatively high permeability, and
containing elevated levels of contamination. A similar zone can be generally correlated in
well logs throughout much of the PVOU. Contamination appears to preferentially travel
within this zone, as concentrations within it are typically higher than in horizons above and
below it. Containment of contamination within the intermediate zone is considered
essential to avoid future adverse impacts to deeper zones that provide water to drinking
water wells. Water from the intermediate zone itself provides a small portion of the
drinking water pumped from production wells at the mouth of the Puente Valley.
Compliance Wells
Compliance wells in the shallow zone will be located to ensure adequate monitoring of
contaminant migration both laterally and vertically. Wells must provide sufficient
information to assess whether the remedial action is preventing further migration of
contaminants. The number, location, and monitoring of these wells must ensure that
contamination is not spreading laterally away from areas that are already contaminated, or
vertically into deeper zones.
Compliance wells in the intermediate zone must be located within 2,000 feet of the margins
of the B7 Well Field Area, yet within areas of detectable contamination, as described in the
performance criteria, and further described below. The intent of locating these wells in this
manner is to provide compliance points that are sufficiently distant from existing
contamination above MCLs to provide enough time to ensure that additional actions can be
taken before threshold concentrations are exceeded. The wells must also be sufficient in
number and adequately located to ensure that contamination above MCLs does not migrate
away from the B7 Well Field Area.
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10 SELECTED REMEDY
Locations of all compliance wells are subject to EPA approval. Well screens will generally
be of 20 feet or less. Concentrations in wells vary as a function of screen length because of
blending. Therefore, wells with screens longer than 20 feet are not generally considered
appropriate for monitoring compliance. However, based on conditions encountered during
installation of these wells, it may be appropriate to consider longer screens to ensure
monitoring of several high-permeability zones. Installation of wells with screens exceeding
20 feet will be considered on a case-by-case basis subject to EPA approval.
B7 Well Field Area
The B7 Well Field contains production wells that the San Gabriel Valley Water Company
and the Suburban Water System own. The current extent of intermediate zone ground-
water contamination extends into the B7 Well Field. The intermediate zone objective is to
ensure that contamination does not migrate beyond the B7 Well Field Area. For the
purposes of this remedial action, the B7 Well Field Area is defined as: (1) the wells listed in
Table 5 and (2) the downgradient extent of contamination above MCLs in the vicinity of the
wells listed in Table 5. The intent of defining the zone in this manner is to provide an
adequate basis for designing a remedial action that does not allow contamination to spread
away from its current extent. The B7 Well Field Area is considered to be a generally
elliptical or circular area that encompasses both the B7 wells and the downgradient extent of
contamination.
The FS identifies two approaches that should be able to accomplish the intermediate zone
objectives. The first relies exclusively on installation of a new set of extraction wells
upgradient of the production wells. These new wells must provide sufficient hydraulic
control to capture contamination migrating into the production field. The second approach
incorporates the production wells into the remedial action. If this approach is used, it must
be demonstrated that pumping from the production wells alone, or in combination with
new wells, provides sufficient hydraulic control. For the production wells to be considered
part of the remedial action, the responsible parties will have to provide acceptable
assurances to EPA that the wells will operate in a manner that ensures compliance with the
performance criteria. If other approaches for achieving containment are identified, EPA will
evaluate those methods in accordance with the criteria specified in 40 CFR Section 300.430.
For any remedial approach, compliance will be monitored at wells located along the
margins of the B7 Well Field Area. If a new extraction system is used, monitoring wells
must also be placed to measure the effectiveness of the system preventing migration of
contaminants into the B7 Well Field. Any remedial action selected must, by itself, provide
sufficient capture and be monitored to ensure that the performance criteria are not
exceeded.
Adverse Effects
The term "adverse effects" is included in the performance criteria to prevent the design and
installation of a hydraulic control system that maintains concentrations at compliance wells
below specified thresholds at the expense of protecting production wells that are not part of
the remedy. The principal adverse effect of concern is implementation of the remedial
action in a manner that results in increased contaminant concentrations in wells that are not
part of the remedial action. This requirement prevents, for example, the installation of new
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10 SELECTED REMEDY
extraction wells immediately upgradient of the compliance wells and downgradient of
production wells that are not part of the remedial action. The remedial action must be
protective of the environment and not result in adverse effects, either on production wells,
or on the overall extent of contamination.
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11 Applicable or Relevant and Appropriate
Requirements (ARARs)
Section 121(d) of CERCLA, 42 U.S.C. § 9621(d) requires that remedial actions at CERCLA
sites attain (or justify the waiver of) any federal or state environmental standards,
requirements, criteria, or limitations that are determined to be legally applicable or relevant
and appropriate. These applicable or relevant and appropriate requirements are referred to
as "ARARs." Federal ARARs may include requirements promulgated under any federal
environmental laws. State ARARs may only include promulgated, enforceable
environmental or facility-siting laws of general application that are more stringent or
broader in scope than federal requirements and that are identified by the state in a timely
manner.
An ARAR may be either "applicable," or "relevant and appropriate," but not both. If there is
no specific federal or state; ARAR for a particular chemical or remedial action, or if the
existing ARARs are not considered sufficiently protective, then other guidance or criteria to
be considered (TBCs) may be identified and used to ensure the protection of public health
and the environment. The NCP, 40 C.F.R. Part 300, defines "applicable," "relevant and
appropriate," and "to be considered" as follows:
Applicable requirements are those cleanup standards, standards of control, or other
substantive requirements, criteria, or limitations promulgated under federal
environmental or state environmental or facility siting laws that specifically address a
hazardous substance, pollutant, contaminant, remedial action, location, or other
circumstances found at a CERCLA site. Only those state standards that are identified by
a state in a timely manner and that are more stringent than federal requirements may be
applicable.
Relevant and appropriate requirements are those cleanup standards, standards of
control, and other substantive requirements, criteria, or limitations promulgated under
federal environmental or state environmental or facility siting laws that, while not
"applicable" to a hazardous substance, pollutant, contaminant, remedial action, location,
or other circumstance at a CERCLA site, address problems or situations sufficiently
similar to those encountered at the CERCLA site that their use is well suited to the
particular site. Only those state standards that are identified in a timely manner and
that are more stringent than federal requirements may be relevant and appropriate.
TBCs consist of advisories, criteria, or guidance that EPA, other federal agencies, or
states developed that may be useful in developing CERCLA remedies. The TBC values
and guidelines may be used as EPA deems appropriate.
ARARs are identified on a site-specific basis from information about the chemicals at the
site, the remedial actions contemplated, the physical characteristics of the site, and other
appropriate factors. ARARs include only substantive, not administrative, requirements, and
pertain only to onsite activities. Offsite activities must comply with all applicable federal,
SCO/982660003.DOC/3-97
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11 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS (ARARS)
state, and local laws, including both substantive and administrative requirements, that are
in effect when the activity takes place. There are three general categories of ARARs:
Chemical-specific ARARs are health- or risk-based concentration limits, numerical
values, or methodologies for various environmental media (i.e., ground water, surface
water, air, and soil) that are established for a specific chemical that may be present in a
specific media at the site, or that may be discharged to the site during remedial
activities. These ARARs set limits on concentrations of specific hazardous substances,
pollutants, and contaminants in the environment. Examples of this type of ARAR
include state and federal drinking water standards.
Location-specific ARARs set restrictions on certain types of activities based on site
characteristics. Federal and state location-specific ARARs are restrictions placed on the
concentration of a contaminant or the activities to be conducted because they are in a
specific location. Examples of special locations possibly requiring ARARs may include
floodplains, wetlands, historic places, and sensitive ecosystems or habitats.
Action-specific ARARs are technology- or activity-based requirements that are
triggered by the type of remedial activities under consideration. Examples of this type
of ARAR are RCRA regulations for waste treatment, storage, or disposal.
EPA has evaluated and identified the ARARs for the selected remedy in accordance with
CERCLA, the NCP, and EPA guidance, including the CERCLA Compliance with Other Laws
Manual, Part I (Interim Final), OSWER Directive 9234.1-01 (EPA, 1988a) and CERCLA
Compliance with Other Laws Manual, Part II, OSWER Directive 9234.1-02 (EPA, 1989).
11.1 Chemical-specific ARARs
The chemicals of potential concern for the PVOU are VOCs that were detected in ground
water in the PVOU. Table 1 lists these VOCs and their chemical-specific ARARs.
11.1.1 Federal Drinking Water Standards
EPA has established MCLs, 40 CFR. Part 141, under the Safe Drinking Water Act (SDWA),
42 U.S.C. §§ 300f-j, to protect public health from contaminants that may be found in
drinking water'sources. MCLs are applicable at the tap for water that is delivered directly
to 25 or more people or to 15 or more service connections.
Under the SDWA, EPA has also designated Maximum Contaminant Level Goals (MCLGs),
40 C.F.R. Part 141, which are health-based goals that may be more stringent than MCLs.
MCLGs are set at levels, including an adequate margin of safety, where no known or
anticipated adverse health effects would occur. MCLGs greater than zero are relevant and
appropriate where multiple contaminants in ground water or multiple pathways of
exposure present unacceptable health risks (EPA, 1988b). One chemical detected in the
PVOU ground water, 1,1,2-trichloroethane, has an MCLG that is more stringent than its
MCL.
Under Section 300.430(f)(5) of the NCP, remedial actions must generally attain MCLs and
nonzero MCLGs if the contaminated water is a current or potential source of drinking
water. The 1995 Water Quality Control Plan for the Los Angeles Region (Basin Plan)
SCO/982660003.DOC/3-97 11-2
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11 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS (ABARS)
designates all of the contaminated ground water in the PVOU as current and potential
sources of drinking water. However, since this ROD selects an interim remedial action to
contain contaminant migration, no final cleanup standards are established for the
restoration of ground water. Final cleanup standards will be established in a Final ROD.
For this Interim ROD, EPA has determined that the federal MCLs and nonzero MCLGs
listed in Table 1 are ARARs for any ground water that is treated and used for domestic,
municipal, industrial, or agricultural purposes, and for any ground water that is discharged
to the environment. In addition, these MCLs and MCLGs are ARARs for currently
uncontaminated ground water in the intermediate zone downgradient from the B7 Well
Field Area (EPA, 1988a).
If treated ground water is to be delivered into a public water supply, all legal requirements
for drinking water in existence at the time that the water is served will have to be met
because EPA considers the service of water to the public to be an offsite activity.
11.1.2 California Drinking Water Standards
California has established state MCLs for sources of public drinking water, under the
California Safe Drinking Water Act of 1976, Health and Safety Code (H&SC) §§ 4010.1 and
4026(c), California Code of Regulations (CCR) Title 22, §§ 64431 and 64444. Some state
MCLs are more stringent than the corresponding federal MCLs. EPA has determined that
the more stringent state MCLs are relevant and appropriate for the PVOU. There are also
some chemicals that lack federal MCLs. Where state MCLs exist for chemicals that lack
federal MCLs, EPA has determined that the state MCLs are relevant and appropriate for the
PVOU. State MCLs apply to remedial actions in the PVOU in the same manner as federal
MCLs. Table 1 identifies the state MCLs that are ARARs for this remedial action.
11.2 Location-specific ARARs
This ROD specifies performance criteria for the remedy. As such, the locations of
remediation facilities (e.g., wells, treatment plaint, and pipelines) are not specifically
identified herein. Locations of remediation facilities will be determined during the remedial
design, and will conform, to the location-specific ARARs identified below.
11.2.1 Location Standards for TSD Facilities
California Code of Regulations, Title 22, Section 66264.18 establishes location standards for
Hazardous Waste Treatment, Storage, and Disposal Facilities (TSDFs). Subsection
66264.18(a) prohibits the placement of TSDFs within 200 feet of a fault displaced during the
Holocene epoch. Subsection 66264.18(b) requires that TSDFs located within a 100-year
floodplain be capable of withstanding a 100-year flood. These standards are applicable to
the construction of any new ground-water extraction and treatment facilities used as part of
this remedial action.
11.2.2 Endangered Species Act
The Endangered Species Act, 15 U.S.C. §§ 1531-1544, and implementing regulations,
40 C.F.R. § 6.302(h), 50 C.F.R. Parts 17, 222 and 402, are applicable to any remedial actions
that impact a proposed or listed threatened or endangered species or destroy or adversely
SCO/982660003.DOC/3-97 U-3
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11 APPUCABIE OB RELEVANT AND APPROPRIATE REQUIREMENTS (ARABS)
modify the critical habitat of a listed species. The Preliminary Baseline Risk Assessment for
the PVOU identified native plant communities, wildlife, special-status species, and sensitive
habitat within the general area of the PVOU. No endangered species are known or
suspected to occur in the locations where remedial action facilities might be constructed. If,
however, it appears during the implementation of the remedial action that construction
activities or the discharge of treated ground water might adversely affect a proposed or
listed species, EPA will consult with the U.S. Fish and Wildlife Service (FWS) in accordance
with 50 CFR Part 402 and ensure that regulatory requirements are followed so that adverse
impacts are avoided or mitigated.
11.2.3 California Fish and Game Code
California Fish and Game Code sections 2080,5650(a), (b), and (f), 12015, and 12016 prohibit
the discharge of harmful quantities of hazardous materials into places that may
deleteriously affect fish, wildlife, or plant life. These provisions are applicable if the
remedial action will result in the discharge of treated ground water to surface waters.
11.2.4 Archaeological and Historic Preservation Act
This statute and implementing regulations, 16 U.S.C. § 469,40 C.F.R. Part 6.301 (c), establish
requirements for the evaluation and preservation of historical and archaeological data that
may be destroyed through alteration of terrain as a result of a federal construction project or
a federally licensed activity or program. The only known site of historical interest in the
PVOU is the Workman and Temple Family Homestead Museum, located at 15415 Don
Julian Road (a short distance north of cluster well MW6-6). These requirements are
applicable if the remedial action will interfere with this facility.
11.2.5 Historic Sites, Buildings, and Antiquities Act
The Historic Sites, Buildings, and Antiquities Act, 16 U.S.C. §§ 461-467,40 C.F.R.
Part 6.301(a), requires federal agencies to consider the existence and location of landmarks
on the National Registry of Natural Landmarks to avoid undesirable impacts on such
landmarks. The remedial action is not anticipated to affect any of the facilities regulated
under the act. However, during preliminary design, a complete review will be made of
impacted areas.
11.3 Action-specific ARARs
11.3.1 Local Air Quality Management
One VOC treatment technology that may be used is air stripping. Air emissions from air
strippers are regulated by the California Air Resources Board, which implements the federal
Clean Air Act (CAA), as well as the air pollution control requirements of the California
H&SC, through local air quality management districts. Local districts may impose
additional regulations to address local air emission concerns. The local air district for the
PVOU is the South Coast Air Quality Management District (SCAQMD). The SCAQMD has
adopted several rules that are ARARs for air stripper emissions and construction activities.
SCO/982660003.D003-97
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11 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS (ARARS)
SCAQMD Regulation XIII, comprising Rules 1301 through 1313, establishes new source
review requirements. Rule 1303 requires that all new sources of air pollution in the district
use best available control technology (BACT) and meet appropriate offset requirements.
Emissions offsets are required for all new sources that emit in excess of one pound per day.
SCAQMD Rule 1401 requires that best available control technology for toxics (T-BACT) be
employed for new stationary operating equipment, so that the cumulative carcinogenic
impact from air toxics does not exceed the maximum individual cancer risk limit of 10 in
1 million (1 x 10-s). Many of the contaminants found in the PVOU ground water are air
toxics subject to Rule 1401.
SCAQMD Rules 401 through 403 are also ARARs for construction and operation of remedial
action facilities. SCAQMD Rule 401 limits visible emissions from a point source. Rule 402
prohibits discharge of material that is odorous or causes injury, nuisance, or annoyance to
the public. Rule 403 limits downwind particulate concentrations.
11.3.2 Federal Clean Water Act and California Porter-Cologne Water Quality Act
California's Porter-Cologne Water Quality Act incorporates the requirements of the federal
Clean Water Act (CWA) and implements additional standards and requirements for surface
and ground waters of the state.
Water Quality Control Plan for the Los Angeles Region (Basin Plan)
The RWQCB formulates and enforces water quality standards through a Basin Plan. The
Basin Plan identifies the beneficial uses of surface and ground waters in the San Gabriel
River watershed and establishes water quality objectives necessary to protect these
beneficial uses. Water quality objectives impose limitations on receiving waters, rather than
discharges, and are applicable to any water body that receives discharge from remedial
activities in the PVOU.
The selected remedial action may result in the discharge of treated ground water to Puente
Creek immediately upstream from San Jose Creek, which is tributary to the San Gabriel
River. Table 2-1 of the Basin Plan identifies the following beneficial uses for San Jose Creek:
Municipal and domestic supply (potential beneficial use)
Ground-water recharge (intermittent beneficial use)
Water contact recreation (potential beneficial use)
Noncontact water recreation (intermittent beneficial use)
Warm fresh water habitat (intermittent beneficial use)
Wildlife habitat (existing beneficial use)
The Basin Plan identifies the same beneficial uses for the segment of the San Gabriel River
below the confluence with San Jose Creek.
Since municipal and domestic water supply is a potential beneficial use of these surface
waters, the MCLs listed in Table 1 are applicable as water quality objectives for San Jose
SCO/98Z660003.DOC/3-97 ,, .5
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11 APPLICABLE Ofl RELEVANT AND APPROPRIATE REQUIREMENTS (ARABS)
Creek. In addition, the following water quality objectives from Table 3-8 of the Basin Plan
are ARARs for San Jose Creek and the relevant segment of the San Gabriel River:
Total Dissolved Solids: 750 mg/L
Sulfate: 300 mg/L
Chloride: 150 mg/L
Boron: 1.0 mg/L
Nitrogen (NO3-N + NO2-N): 8 mg/L
The Basin Plan also establishes water quality objectives for ground water in the Puente and
Main San Gabriel Basins (Table 3-10). These water quality objectives are applicable to any
discharge that impacts ground water. However, if the selected remedy results in discharge
to surface waters, it is expected to have a negligible effect on ground water (Camp, Dresser
and McKee Inc., 1988).
State Water Resources Control Board Resolution 68-16
The Basin Plan also incorporates the State Water Resources Control Board (SWRCB) policy
"Statement of Policy with Respect to Maintaining High Water Quality in California"
(Resolution 68-16). Resolution 68-16 requires that existing water quality be maintained
unless it is demonstrated that a change will benefit the people of California, will not
unreasonably affect present or potential uses, and will not result in water quality less than
prescribed by other state policies. Any activity that may increase the volume or
concentration of a waste discharged to surface or ground water is required to use the "best
practicable treatment or control."
Resolution 68-16 is applicable to discharges of treated ground water. The RWQCB requested
that the PVSC evaluate the potential impact of nitrates and TDS contained in treated ground
water on receiving waters and investigate alternative discharge options. The PVSC
complied with this request and prepared a report, Puente Valley Operable Unit Discharge
Options Study Report (Camp, Dresser & McKee Inc., 1998), which concluded that any
discharges from the remedial action will not significantly impact receiving waters or their
beneficial uses. The report also identified substantial costs associated with treatment of
nitrates and TDS and failed to identify significant reliable alternative uses for nonpotable
treated ground water. The RWQCB has determined that the selected remedy will comply
with this ARAR as long as discharges to surface water are monitored and the estimated
impacts on receiving waters are correct (Consideration of Approval of a Resolution Supporting
U. S. EPA's Proposed Plan for the Puente Valley Superfund Cleanup. Resolution 98-016, RWQCB,
September 14,1998).
State Water Resources Control Board Resolution 92-49
Subsection III.G of the SWRCB's "Policies and Procedures for Investigation and Cleanup
and Abatement of Discharges under Water Code Section 13304" (Resolution 92-49) requires
attainment of background water quality or, if background levels cannot be restored, the best
quality of water that is reasonable. Resolution 92-49 is not an ARAR because this is an
interim remedial action to contain the spread of contamination, rather than a final action to
restore ground water in the PVOU.
SCO/982660003.DOC/3-97 11-6
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11 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS (ARARS)
11.3.3 Standards Applicable to CERCLA Section 104(b) Discharges to Surface Waters
Site investigation activities undertaken pursuant to CERCLA § 104(b) are considered to be
removal actions. It is EPA policy that removal actions "comply with ARARs to the extent
practicable, considering the exigencies of the circumstances." (55 Fed. Reg. 8756).
It is possible that certain site investigation activities will take place during remedial design,
which will result in temporary high-flow, high-volume discharges of contaminated ground
water (e.g., discharges from aquifer testing and spinner logging/depth-specific sampling of
water supply wells). EPA has considered the best available technology economically
achievable (BAT) for treatment and disposal of these discharges. The four disposal options
that EPA considered are: (1) discharge to an existing drinking water distribution system,
(2) onsite storage and disposal at a Resource Conservation and Recovery act (RCRA)-
approved hazardous waste facility, (3) discharge to a sanitary sewer for treatment at a
wastewater treatment plant, and (4) onsite treatment and discharge to surface water
channels. EPA has concluded that compliance with chemical-specific ARARs is not
practicable, considering the exigencies of the circumstances, for many temporary high-flow,
high-volume discharges.
EPA has determined that compliance with chemical-specific ARARs is practicable and
necessary for CERCLA § 104(b) activities that do not result in temporary high-flow, high-
volume discharges. EPA will determine the application of chemical-specific ARARs to
CERCLA § 104(b) activities on a case-by-case basis. Where practicable, these discharges
must comply with ARARs.
11.3.4 California Hazardous Waste Management Program
The federal RCRA establishes requirements for the management and disposal of hazardous
wastes. In lieu of the federal RCRA program, the State of California is authorized to enforce
its Hazardous Waste Control Act, and implement regulations (CCR Title 22, Division 4.5),
subject to the authority retained by EPA in accordance with the Hazardous and Solid Waste
Amendments of 1984 (HSWA). California is responsible for permitting treatment, storage,
and disposal facilities within its borders and carrying out other aspects of the RCRA
program. Some of the Title 22 regulations are applicable to the generation and disposal of
hazardous wastes in the PVOU.
Hazardous Waste Generator Requirements
CCR Title 22 establishes requirements applicable to generators of hazardous waste.
Implementation of the remedial action may generate hazardous waste as a result of ground-
water monitoring and well installation (e.g., contaminated soil and ground water and used
personal protective equipment). Hazardous waste may also be generated as a result of
ground-water treatment to remove VOCs (e.g., spent carbon). These requirements are
applicable to remedial actions in the PVOU.
The preamble to the NCP clarifies that when noncontiguous facilities are treated as one site,
the movement of hazardous waste from one facility to another is subject to RCRA manifest
requirements (55 Fed. Reg. 8691). Manifest requirements are ARARs in the event that the
remedial action involve multiple water treatment units at different locations and require the
movement of hazardous wastes (e.g., spent carbon) between these locations.
SCO/982660003.DOC/3-97 ,, .7
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11 APPtlCABlEOfl RELEVANT AND APPROPRIATE REQUIREMENTS (ARARS)
Land Disposal Restrictions
CCR Title 22 defines hazardous wastes that cannot be disposed of to land without
treatment. Land disposal requirements are applicable to the disposal of spent carbon
generated during the treatment of ground water for removal of VOCs, if carbon adsorption
is used, and the disposal of residuals associated with ground-water monitoring and well
installation (e.g., contaminated soil and ground water, used personal protective equipment).
Hazardous Waste TSD Facility Requirements
CCR Title 22, Division 4.5, Chapter 14, specifies Hazardous Waste TSDF requirements that
regulate the design, construction, operation, and closure of RCRA-permitted TSDFs. Since
the contaminated ground water is sufficiently similar to RCRA hazardous wastes, Title 22
TSDF requirements are relevant and appropriate for the design, construction, operation, and
closure of any ground-water treatment systems. The Title 22 ARARs include the
substantive requirements of the following provisions:
Section 66264.14: Security Requirements
Section 66264.25: Seismic and Precipitation Standards
Section 66264.94: Ground Water Protection Standards
Sections 66264.111-115: Closure of Treatment Units
Sections 66264.170-178: Use and Management of Containers
Sections 66264.600-603: Standards for Miscellaneous Treatment Units
11.4 ARARs Waivers
This remedial action is an interim measure to contain contaminant migration. EPA,
therefore, has not established chemical-specific ARARs for restoration of the contaminated
portions of the PVOU. These ARARs will be addressed in the ROD for the PVOU.
SCO/982660003.DOC/3-97 11 -8
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12 Documentation of Significant Changes
EPA presented the Proposed Plan for this interim action for public comment in January
1998. The Proposed Plan identified Alternative 3 as the preferred remedy and proposed
that it be implemented through a performance-based approach. Alternative 3 includes
ground-water extraction, containment, and treatment of contaminated ground water, and
monitoring to ensure compliance with RAOs. EPA has reviewed all written and verbal
comments submitted during the public comment period. Upon review of these comments,
it was determined that no significant changes to the selected remedy, as presented in the
Proposed Plan, were necessary.
SCCV982660003.00O3-97 ,2-i
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13 Statutory Determinations
As required under Section 121 of CERCLA, EPA must select remedies that are protective of
human health and the environment, comply with applicable or relevant and appropriate
requirements (unless a statutory waiver is justified), are cost-effective, and utilize
permanent solutions and alternative treatment technologies or resource recovery
technologies to the maximum extent practicable. In addition, CERCLA includes a
preference for remedies that employs treatment that permanently and significantly reduces
the volume, toxicity, or mobility of hazardous wastes. The following sections discuss how
the selected remedy meets these statutory requirements.
13.1 Protection of Human Health and the Environment
The selected remedy will protect human health and the environment by limiting further
downgradient and vertical migration of contaminated ground water and by removing
significant contaminant mass from the aquifer. The remedy will reduce potential risks by
decreasing the likelihood and magnitude of future exposure to contaminated ground water.
Contaminant concentrations in the ground water in the areas to be addressed by the remedy
are currently tens to thousands of times higher than acceptable levels. Available treatment
technologies are technically feasible and proven effective in meeting ARARs for VOCs in the
treated ground water and air. Implementation of the remedy will not pose unacceptable
short-term risks. In addition, no adverse cross-media impacts are expected.
13.2 Compliance with ARARs
The selected remedy shall comply with all ARARs, which are listed in Section 11 of this
ROD. No ARARs waivers are expected to be needed. Because this is an interim action, EPA
has not established chemical-specific ARARs for restoration of the ground water.
13.3 Cost-Effectiveness
EPA believes the selected remedy is cost-effective and uses permanent solutions and
treatment technologies to the maximum extent practicable. The selected remedy will reduce
the mobility of the contaminants in the aquifer and will permanently reduce the volume of
contamination by limiting the migration of contaminants and removing contaminant mass.
13.4 Community Acceptance
o
Several commenters expressed support for EPA's proposed remedy. Some commenters did
not believe that the remedy was necessary or supported by the information that has been
collected to date. EPA has determined that the preferred alternative presented in the
Proposed Plan represents the most appropriate remedy for the ROD site. None of the
comments suggested a change to the overall remedy that EPA selected. The comments
SCO/982660003.DOC/3-97 13.,
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13 STATUTORY DETERMINATIONS
received during the public comment period, along with EPA's responses, are presented in
Part H of this ROD.
13.5 Utilization of Permanent Solutions and Alternative
Treatment Technologies to the Maximum Extent
The selected remedy will include ground-water extraction and treatment for removal of
VOCs to meet the performance criteria specified in this ROD. The selected remedy,
therefore, is expected to use permanent solutions and alternative treatment technologies to
the maximum extent practicable.
13.6 Preference for Treatment as a Principal Element
The selected remedy will include ground-water treatment as a principal element of the
remedy to meet the Performance Criteria.
13.7 Five-Year Reviews
Because the remedy will result in hazardous substances remaining onsite above health-
based levels, EPA shall conduct a review of the remedy, pursuant to CERCLA Section 121,
42 U.S.C. Section 9621, at least once every 5 years after commencement of remedial action.
The review will assess whether the remedy continues to provide adequate protection of
human health and the environment. If it is determined that the remedy is no longer
protecting human health and the environment, then modifications to the remedy will be
evaluated and implemented as necessary.
SCO/982660003.DOO3-97 13-2
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14 References
California Department of Water Resources. Bulletin 45. South Coastal Basin Investigation.
Eckis, Rollin. 1934.
. Bulletin 104-2. San Gabriel Valley: Appendix A. 1966.
California Department of Water Resources. The California Water Atlas. 1979.
Camp Dresser & McKee Inc. Statement of Work, Puente Valley Operable Unit Interim RI/FS.
September 1993a.
. Puente Valley Operable Unit Interim Remedial Investigation Report. 1997.
. Puente Valley Operable Unit Discharge Options Study Report. August 10,1998.
City of Industry. City of Industry's Comments on Feasibility Study Technical Memorandum No. 1.
James A. Geocaris. December 1995.
Environmental Protection Agency. Supplemental Sampling Program Report, San Gabriel Basin,
Los Angeles, California. Prepared by CH2M HILL. 1986.
. CERCLA Compliance with Other Laws Manual, Part I (Interim Final). OSWER
Directive 9234.1-01. 1988a.
. Guidance on Remedial Actions for Contaminated Ground Water at Superfund Sites.
OSWER Directive 9283.1-2. 1988b.
. CERCLA Compliance with Other Laws Manual, Part II. OSWER Directive
9234.1-02. 1989.
-. Role of the Baseline Risk Assessment in the Superfund Remedy Selection Decisions.
OSWER Directive 9355.0-30. April 22,1991.
. Health Effects Assessment Summary Tables - Annual FYI -1991. OERR 9200.6-
303(91-1). Office of Research and Development. January 1992a.
. Interim San Gabriel Basin Remedial Investigation Report. Prepared by
CH2M HILL. July 1992b.
-. Integrated Risk Information System. Chemical Files. U.S. EPA Integrated Risk
Information System Database. Office of Research and Development. Cincinnati, Ohio.
1993a.
. Master List of Chemical Specific Risk Assessment Issues. Office of Research
and Development, Environmental Criteria and Assessment Office. November 23,1993b.
. Puente Valley Operable Unit, Data Collection and Evaluation Report. April 1993c.
. Puente Valley Operable Unit, Preliminary Baseline Risk Assessment. Prepared by
CH2MHILL. March 1994.
SCO/98267OXKDOC/3-97 14-1
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H REFERENCES
-. Puente Valley Operable Unit Interim Feasibility Study. Prepared by CH2M HILL.
1997.
Federal Register. Volume 55, Number 8756.
Los Angeles Regional Water Quality Control Board. Consideration of Approval of a Resolution
Supporting U.S. EPA's Proposed Plan for the Puente Valley Superfund Cleanup.
Resolution 98-016, RWQCB. September 14,1998.
James. M. Montgomery. Remedial Investigation Report for the Glendale Study Area. 1992.
Puente Basin Watermaster. Ninth Annual Report of the Puente Valley Basin Watermaster. Fiscal
Year 1994-1995. September 1995.
SCO/982670004.DOC/3-97
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Tables
SCO/982670004.DOC/1-97
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Table 1
ARARs for Chemicals of Potential Concern
Compound
1, 1'Dichloroethane
1, 1-Dlchloroethene
1, 1, 1'Trlchloroethane
1 ,1 ,2-Trichloro-1 ,2,2-Hrifluoroethane
1 ,1 ,2-Trichloroethane
1 , 1 ,2,2-Tetrachloroethane
1 ,2-Dichlorobenzene
1,2-Dichloroethane
1,2-Dlchloroethene (total)
1 ,2-Dichloropropane
1 ,2.4-Trichlorobenzene
1 ,2,4-Trimethylbenzene
1 ,3-Dichlorobenzene
1 ,3 B Dichloropropene
1 ,3,5-Trimethylbenzene
1 ,4-Dichlorobenzene
2-Propanone
Benzene
bis(2-Ethythexy))phthalate
Bromochloromethane
Bromodichloromethane2
Bromoform2
Bromomethane
n-Butylbenzene
sec-Butylbenzene
tert-Butylbenzene
Carbon Oisulfide
Carbon Tetrachloride
Chlorobenzene
Chloroethane
Chloroform1
cis-1 ,2-Dichloroethene
cis-1 ,3-Dichloropropane
Dibromochloromethaine2
Dibromochloroproparie
Di-n-butylphthalate
Dichlorofluoromethane
Ethylbenzene
Isopropyl alcohol
Isopropyl benzene
Methylene Chloride
Naphthalene
Styrene
ARAR
(M9/L)
5
6
200
1,200
3
1
600
0.5
6'
5
70
-
600
0.5
-
5
-
1
4
-
100
100
-
-
-
-
0.5
70
100
6
-
100
0.2
-
c
700
-
-
5
-
100
Source
California MCL
California MCL
Federal MCL
California MCL
Federal MCLG
California MCL
Federal MCL
California MCL
California MCL
Federal MCL
Federal MCL
Federal MCL
California MCL
-
California MCL
-
California MCL
California MCL
-
Federal MCL
Federal MCL
-
-
-
-
-
California MCL
California MCL
-
Federal MCL
California MCL
-
Federal MCL
Federal MCL
-
C
Federal MCL
-
-
Federal MCL
-
Federal MCL
SCO/982710002 .DOC-97
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Table 1
ARARs for Chemicals of Potential Concern
Compound
ARAR
(H9/L)
Source
Tetrachloroethene
Federal MCL
Total petroleum hydrocarbons
Total petroleum hydrocarbons-volatiles
trans-1,2-Dichloroethene
10
California MCL
trans-1,3-Dichloropropane
Trichloroethylene
Federal MCL
Trichlorofluoromethane
150
California MCL
Toluene
ISO
California MCL
Vinyl Chloride
0.5
California MCL
m.p-Xylene
o-Xylene0
Xylenes, total
1,750
California MCL
Value for the cis-isomer; value for trans-isomer is 10 ng/L
2These chemicals are trihalomethanes (THMs); the MCL listed is for all four THMs:
chloroform, bromodichloromethane, dibromocnloromethane, and bromoform.
3Value for total xylenes is 10,000 ng/L; no values are provided for individual isomers.
Notes: - indicates "no MCL has been established or proposed." '
Bold/Italicized text indicates compounds detected in groundwater during Rl (PVSC
monitoring wells or Suburban Water Systems wells).
SCO/982710002.DOC-97
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Table 2
Estimated Total Noncancer Hazard Index from Domestic Use of Groundwater
Puente Valley Operable Unit
Wells
Production Well 08000077
Production Well 98000068
Production Well 980001 08
Well Group 1
Well Group 2
Well Group 3
Well Group 4
Well Group 5
Well Group 6
Well Group 7
Well Group 8
Average Exposure
Ingestion
0.03
0.07
0.2
0.6
1
40
2
20
0.9
1
0.4
Inhalation
0.03
0.07
0.2
0.6
1
30
2
20
0.9
1
0.4
Reasonable Maximum
Exposure
Ingestion
0.03
0,09
0.2
0.6
2
60
2
40
1
2
0.5
Inhalation
0.03
0.09
0.2
0.6
2
60
2
40
1
2
0.5
Major Chemical Contributors
1 ,1-Dichloroethene, Trichloroethene
Tetrachloroethene, Trichloroethene
1 ,1-Dichloroethene, Trichloroethene
1 ,1-Dichloroethene, Trichloroethene
1,1-Dichloroethene, 2-Propanone
1 ,1-Dichloroethene, Trichloroethene.
Tetrachloroethene, Trichloroethene
Methylene Chloride, 2-Propanone, Trichloroethene
Tetrachloroethene, Trichloroethene
Tetrachloroethene, Trichloroethene
1 ,1-Dichloroethene, Trichloroethene
SCO/982710001.DOC-97
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Table 3
Estimated Total Excess Lifetime Cancer Risk from Domestic Use of Groundwater
Puente Valley Operable Unit
Wells
Production Well 08000077
Production Well 98000068
Production Well 98000108
Well Group 1
Well Group 2
Well Group 3
Well Group 4
Well Group 5
Well Group 6
Well Group 7
Well Group 8
Average Exposure
Ingestion
5x1 0'7
3x1 0'6
4x1 0"6
4x1 0"6
4x1 0'5
2x1 0'4
1x10'4
4x1 0'4
4x1 0'5
6x1 0'5
4x1 0"6
Inhalation
7x10'8
2x10'7
5x1 0'7
7x1 0'7
8x10'6
1x10-"
6x1 0'6
2x10'4
4x1 0'6
2x1 0'6
2x1 0'6
Reasonable Maximum
Exposure
Ingestion
2x1 0'6
1x1 0'5
2x1 0'5
1x10's-
1x10'4
1x10'3
4x1 0'4
3x1 Q-3
2x1 0'4
4x1 0'4
2x1 0's
Inhalation
3x1 0'7
7x1 0'7
2x1 0'8
2x1 0"6
3x1 0'5
7x1 0"4
3x1 0'5
2x1 0'3
2x1 0's
2x1 0'5
8x1 0"6
Major Chemical Contributors
Tetrachloroethene
Tetrachloroethene, Trichloroethene
Tetrachloroethene, Trichloroethene
Tetrachloroethene, Trichloroethene
1 ,4-Dichlorobenzene, Tetrachloroethene, Vinyl
Chloride
1 ,2-Dichloroethane, Tetrachloroethene,
Trichloroethene
Tetrachloroethene, Vinyl Chloride
1 ,2-Dichloroethane, Methylene Chloride,
Trichloroethene
Tetrachloroethene, Trichloroethene
Tetrachloroethene
Tetrachloroethene, Trichloroethene
:710001.00C-97
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Table 4
Cost Comparison of Alternatives1
($ 1,000s)
Alternative
2
3
4
Capital Costs
$2,344
$8,276
$11.751
Annual O&M Costs
$360
$1 ,270
$1,634
Net Present Worth
(30-years @ 5%)
$7,878
$27,798
$36,869
1 Net Present Worth is based on discharge to San Jose Creek with treatment for VOCs only.
SCO/982660008.DOC/1-97
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Table 5
B7 Production Wells
Puente Valley Operable Unit
Well Identification
152W1
147W1
105W1
134W1
150W1
147W3
B7E
89
B11A
B7B
B7C
B7D
B9B
B11B
Station Identification
01900337
01901596
01901608
01901623
01902519
08000077
08000122
91901437
91901439
91901440
98000068
98000094
98000099
98000108
SCO/982660008.DOC/1 -97
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INTERIM RECORD OF DECISION
SAN GABRIEL VALLEY SUPERFUND SITE
PUENTE VALLEY OPERABLE UNIT
CITY OF INDUSTRY, CALIFORNIA
Volume 2
September 1998
United States Environmental Protection Agency
Region IX - San Francisco, California
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Part II
Responsiveness Summary
This section presents the United States Environmental Protection Agency's (EPA's) responses to
the written and oral comments received at the public meeting and during the public comment
period. Comments were received from nine parties. This part of the Record of Decision (ROD)
is divided into responses for each of the individuals or entities that provided written comments.
Comments are expressed in italics; EPA's responses in plain text.
All of the oral questions and comments were responded to directly at the public meeting. These
comments or questions and the associated responses are included in the transcript for the public
meeting, attached as Appendix A to this Responsiveness Summary.
Responses to Written Comments
This section provides responses to written comments that EPA received during the public
comment period. Comments were received from: City of Industry and the Industry Urban-
Development Agency; Suburban Water Systems; Central Basin Water Association; Zevnick,
Horton, Guibord, McGovern, Palmer & Fognani on behalf of Cleveland Pneumatic Corporation;
San Gabriel Valley Water Company; Richard A. Sullivan; Royall K. Brown; Law Offices of
Daniel Romano on behalf of Goe Engineering Company, Incorporated; and the Puente Valley
Steering Committee.
Responses to Comments from City of Industry and Industry Urban-
Development Agency (City), dated March 16,1998
City Comment IA: The performance standards for each extraction area (Proposed Plan, p. 7)
are too vague. Those parties who undertake to implement the remedy cannot tell, from the
standards as set out in the Proposed Plan, what volatile organic chemical ("VOC") contaminant
readings at which locations at the mouth of the PVOU will trigger an obligation to do what kinds
of additional remedial work.
The performance criteria should be made more detailed in the ROD in at least the following
ways.
I. Provide more guidance as to the locations of the ground-water monitoring wells used
to measure the performance standards.
2. Specify the VOC levels to be used for the performance standards, and set them at no
less than 10 times MCL.
Also, in l he shallow zone, the group of cooperating potentially responsible parties organized as
the Puente Valley Steering Committee (PVSC) has collected data over the last several months
demonstrating that the plume of contaminated ground water in the shallow zone migrates as
three subplumes near the mouth of the PVOU, where the Proposed Plan recommends placing the
1 .
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shallow zone extraction wells. In detailing the remedy and performance standards for the
shallow zone, the ROD should allow for a remedy that addresses each of the subplumes
separately.
EPA's Response: The performance criteria included in this ROD contain detailed information
on the location of ground-water wells that will be used to monitor compliance with the
performance criteria in both the shallow and intermediate zones (see Section 10 of the ROD).
The ROD also specifies the contaminant concentrations that must be maintained.
The selected remedial action for the PVOU is containment of contaminated ground water in the
shallow and intermediate zones at the mouth of Puente Valley. The ROD incorporates a
performance-based approach with specific performance criteria that must be met in order to
achieve the remedial action objectives for the site. The performance-based approach allows
flexibility in how the performance criteria are met. Therefore, if the responsible parties choose to
address the shallow ground-water contamination as three separate plumes, they may do so as long
as the chosen remedial action achieves containment of the contaminated ground water and
complies with the performance criteria specified in the ROD.
City Comment IB: The City and Agency approve of the option in USEPA 's Proposed Plan to
install new extraction wells or to use existing water company supply wells for the intermediate
zone part of the superfund remedy. Proposed Plan, p. 7. Some operating standards for using
water company wells in the superfund remedy would be a useful feature in the ROD. These
standards should be formulated in consultation with the PVSC and the water companies that
own the supply wells, and should take into account the current and likely future operating
conditions of the supply wells in the context of the companies' overall supply systems.
EPA's Response: As of the time of the ROD, the decision to use existing water supply wells in
the intermediate zone portion of the remedy has not been made. If the responsible parties choose
to utilize the existing water supply wells, appropriate standards and documentation will be
necessary to ensure that the requirements of the remedy will be met. Specific details will need to
be defined during the remedial design stage.
City Comment 1C: The City and Agency strongly support USEPA Region IX 's position in favor
of a waiver of the Waste Discharge Requirements (WDR)for total dissolved solids (TDS) and
nitrates for ground water that is extracted and treated for VOC contamination as part of the
PVOU superfund remedy. Proposed Plan, pp. 7-8. As the USEPA's Feasibility Study recounts,
such a waiver will save those who implement the remedy almost $24 million dollars over the life
of the project. Feasibility Study, Table 5-4.
The City and Agency understand that the WDR is a requirement of a state agency, the California
Regional Water Quality Control Board - Los Angeles Region (the "Regional Board"). The City
and Agency already have sent a letter to the Regional Board showing their support for the
waiver, a copy of said letter is attached as Exhibit A to these comments and incorporated into
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them by reference.
In supporting the Regional Board's grant of this waiver, USEPA Region IXshould take at least
the following steps. First, because the Regional Board's WDR is based in part on provisions of
the federal Clean Water Act, Region IXshould inform the Regional Board that the TDS and
nitrate waiver requested for the PVOU super/und remedy is consistent with the applicable
requirements of the Clean Water Act and implementing regulations. Second, the ROD for the
PVOU should make clear that USEPA Region IX does not consider a WDR for TDS and nitrates
to be an ARARfor implementation of the superfund remedy in the operable unit. Third, USEPA
Region IX should affirm in the ROD that the waiver of the WDR would be consistent with all past
and present memoranda of understanding and funding agreements for the Puente Valley area
between the Regional Board and USEPA Region IX.
EPA's Response: The selected remedy allows for the discharge to Puente Creek of treated
shallow ground water containing nitrate and/or TDS in excess of water quality standards, so long
as the discharge does not cause an exceedence of water quality standards in San Jose Creek, the
San Gabriel River or the ground waters of the Puente and Main San Gabriel basins, and so long
as the impacts of the nitrate and TDS on the receiving waters are consistent with the estimates set
forth in the Discharge Options Report prepared by Camp Dresser & McKee, Inc. The Discharge
Options Report found that the impact of the treated ground water discharge to receiving waters
would be insignificant and that alternative disposal options for the treated shallow ground water
were unavailable or very expensive.
On September 14, 1998, the Regional Board approved a resolution in support of EPA's selected
remedy, including the potential discharge of treated shallow ground water. It is not necessary for
the Regional Board to waive discharge requirements for nitrate and TDS. The water quality
standards for nitrate and TDS in San Jose Creek, the San Gabriel River and the Puente and Main
San Gabriel basin ground waters are ARARs for the selected remedy.
City Comment ID: The Regional Board has several important facility specific "hot spot"
cleanups under way, and has made substantial progress since the middle of last year in having
property owners and tenants at those properties plan for, initiate, and continue these cleanups.
Completing appropriate cleanups at "hot spot" sites within the next few years would remove
major contamination from the area's ground water, should help reduce operating and
maintenance costs for the regional PVOU superfund remedy, and could help reduce capital costs
for the shallow zone component of the superfund remedy.
Regional Administrator Felicia Marcus recognized the importance of earlier "hot spot"
cleanups at superfund sites in her letter to Congressman Esteban Torres of March 24, 1997, a
copy of which is attached to these comments as Exhibit B. The City and Agency approve of
Region LX's commitment to encourage the Regional Board to pursue these "hot spot" cleanups
in its memo to the National Remedy Review Board of December 30, 1997. The City and Agency
urge USEPA Region IX to reaffirm this commitment, and to provide meaningful detail about how
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Region IX will fulfill it, in the ROD.
EPA's Response: EPA recognizes the positive impact site-specific cleanups being conducted
under the supervision of the RWQCB by individual facilities have on the quality of ground water
in the PVOU. These cleanups, however, are outside the purview of the EPA regional ground-
water investigation. EPA reiterates its support of the RWQCB's efforts and will continue to
work with the RWQCB.
City Comment IE1: The City believes that the Proposed Plan as developed in the Feasibility
Study as Alternative 3 is justified as a means of containing the existing contamination in the
PVOU at about the point of its current migration to the -west and northwest, and to reduce
substantially its mass over the next several years. The Proposed Plan, however, contains several
features that exaggerate or inaccurately portray the real threat of the existing contamination,
both to public health and to ground water resources in and around the San Gabriel Basin. Four
of the more important of these features are described in this subsection.
These inaccuracies and exaggerations ignore either the existing effective system of state and
local controls on ground water use that protect the public, or the real data on the extent of
existing contamination. Therefore, they should be corrected in the ROD.
1. The Health Risk Assessment and the Unrealistic Assumption of Human Use of Contaminated
Ground water
In its Proposed Plan, USEPA Region IX continues to rely on a health risk assessment that
includes human ingestion ofVOC contaminated ground water in the Puente Valley. As the City
has pointed out, this exposure pathway is highly unrealistic, because a combination of California
law and the system of institutional controls on ground water use in the San Gabriel Valley
effectively prevent anyone from drinking contaminated ground water. See. "Comments on the
Feasibility Study of the Puente Valley Operable Unit...by the City of Industry..., " (October,
1997), a copy of which accompanies these comments as Exhibit C and is incorporated by
reference into them. In fact, USEPA Region IX itself has conceded that this exposure pathway is
unrealistic because of these same state and local laws and controls. Feasibility Study, p. 3-7.
USEPA Region IX should eliminate this exposure pathway from the health risk assessment in the
ROD. The resulting revised assessment will show a more realistic reduced risk to human health.
At the same time, the City expects that the new assessment, and other evidence in the record, will
still support a remedy, like the Proposed Plan, based on containing the western edge of the
regional contamination before it reaches clean areas in the main San Gabriel basin, while
allowing the currently contaminated ground water areas to the east in the Puente Valley to
improve gradually.
EPA's Response: EPA conducted the Baseline Risk Assessment for the PVOU in accordance
with CERCLA, the NCP and relevant EPA guidance. The goal of the risk assessment was to
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perform a preliminary streamlined evaluation of the potential risks associated with contaminated
ground water in the PVOU. To assess potential risks, EPA is required to evaluate the reasonable
maximum exposure (RME) scenario, which is the "highest exposure that is reasonably expected
to occur" under baseline conditions. Under baseline conditions there are no regulatory controls,
such as the federal and state Safe Drinking Water Act regulations or the Rules and Regulations of
the Main San Gabriel Basin Watermaster, on the use of contaminated ground water (55 Fed.Reg.
8709). In addition, these restrictions on access to ground waters do not eliminate the exposure
pathway.
EPA's assumption that contaminated ground water in the PVOU could be used as drinking water
is reasonable. All ground water in the PVOU is considered by the State of California to be either
an existing or potential source, of drinking water. Municipal water supply wells currently extract
contaminated ground water from the intermediate zone at the mouth of the Puente Valley.
Municipal water providers have previously produced drinking water from other contaminated
areas in the PVOU and, in at least one instance, recently sought to install a drinking water well in
a highly contaminated area in the PVOU. Therefore, under baseline conditions, human ingestion
of contaminated ground water is a realistic exposure pathway. The results of the risk assessment
support the need for an interim action to prevent further migration of contaminated ground water.
EPA agrees that other evidence in the record supports the selection of this remedy.
City Comment IE2: The City and Agency concur -with USEPA Region IX's objectives to protect
currently uncontaminated areas and reduce impacts on the existing -water supply wells at the
northwestern edge of the regional VOC contamination. Proposed Plan, p. 4. The City and
Agency do not concur with the goals of preventing mid-term movements of higher contamination
into locations that now have lower contamination within the existing regional plumes of ground
water contamination, and ask that Region IX omit these goals from the ROD.
The City takes this position because local governments, water masters and water companies,
applying the system of state and local controls noted above, already manage the currently
contaminated areas without exposing any humans to contaminated ground water, and can
continue to manage the same area without health risks to humans for the next few decades.
Therefore, movement of some current hot spots several hundred yards down gradient into areas
of lower contamination for a few years does not pose any realistic threat.
Ultimately, the City and Agency expect that the Proposed Plan will remove substantial amounts
of VOCs, some of the currently contaminated ground water areas will become clean, and all
such areas will show reduced VOC concentrations. This general, long-term progress should
make the remedy outlined in the Proposed Plan consistent with keeping the PVOU available as a
potential future water supply source over the longer term. Short-term improvements in
contamination levels in every part of the PVOU in every year the super fund remedy operates are
not necessary.
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EPA's Response: The selected remedy does not attempt to control the movement of highly
contaminated ground water into areas of lower contamination, except at the boundaries of the
contaminant plumes at the mouth of Puente Valley. EPA will consider the need for and
feasibility of addressing upgradient contamination when EPA evaluates potential final remedial
actions for the PVOU.
City Comment IE3: In describing the threat to the region's ground water resources, the
Proposed Plan suggests that the contamination currently in the PVOU could flow approximately
6.5 miles through the main San Gabriel Basin and the Whit tier Narrows into the Central Basin.
Proposed Plan, p. 2. There is no support for this suggestion. In fact, the available evidence
shows that there is a large area of clean ground water in the southern part of the main San
Gabriel Basin between the western edge of the PVOU an contamination generated by facilities in
South El Monte and El Monte located between the PVOU and the Whittier narrows. Therefore,
this suggestion should not be included in the ROD.
EPA's Response: In the absence of significant ground-water pumping by production wells
within the San Gabriel Basin, in the vicinity of the mouth of the Puente Valley, ground water
flowing out of the Puente Valley would eventually travel west and southwest towards Whittier
Narrows. This natural flow direction is documented in historical maps of the potentiometric
surface prior to significant pumping in the area. For the effect of ground water pumping near the
mouth of the valley to be considered appropriate as a means of containing contamination, these
wells would need to be considered part of the CERCLA remedy. This option is left open in the
Record of Decision, as well as in the Proposed Plan. Unless pumping at these wells is
considered part of the CERCLA remedy, it cannot be assumed that this pumping will continue
indefinitely, thus preventing migration of Puente Valley contamination through Whittier
Narrows, and into the Central Basin.
City Comment IE4: The Proposed Plan identifies the presence of Dense Non-Aqueous Phase
Liquids ("DNAPLS") as a "principal threat" in the PVOU. Proposed Plan, p. 4. This
identification is surprising because the Remedial Investigation and Feasibility Study contain
extensive data gathered over several years of ground water contamination in the PVOU by
VOCs that are not DNAPLs, but no direct detection of any DNAPL compounds.
While Region IX believes that some indirect evidence exists that "suggests the possible presence
of DNAPLs, " making this mere suggestion into a "principal threat" greatly exaggerates the real
evidence of the DNAPL threat to ground water resources in the PVOU and nearby main San
Gabriel Basin. Hence, it should not be included as a principal threat in the ROD. Instead, the
ROD should rely on the real evidence of ground water contamination in the PVOU from VOCs
that are not DNAPLs, and adopt a remedy, based on the Proposed Plan, that reasonably
addresses this real VOC problem.
EPA's Response: For the VOC contamination in ground water at the PVOU, the concept of
"principal threat" does not apply, therefore it is not included in this Interim ROD.
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City Comment IF: Neither the Proposed Plan nor the Feasibility Study include any assessment
levied by the Main San Gabriel Basin Watermaster. Proposed Plan, pp. 7-8 and Feasibility
Study, Tables 5-4 and 5-5. In the past, the Watermaster has levied several assessments. The
following is a list of these assessments:
Administrative
In-Lieu
Replacement Water
Make-up Water
Special.
The City and Agency recommend that the information about these costs be included in the ROD
for an adopted remedy based on Alternative 3.
As an example, under current local ground water controls, replacement water charges could
apply to both the intermediate and shallow zone components of Alternative 3. In the
intermediate zone, if the project sponsors do not use the existing water supply wells and instead
install their own system, they probably will treat this ground water, which is low in TDS and
nitrates, for the VOCs, and then sell the clean water to a local company. This domestic use will
require the sponsors to pay replacement charges, as well as some of the other Watermaster
Assessments.
In the shallow zone, the project sponsors probably will discharge the ground water, which is
high in TDS and nitrates into a lined portion of the San Jose Creek after they treat it for VOCs.
Such a discharge may or may not be viewed as transport out of the Main San Gabriel Basin,
depending in part on the area where this discharged water reaches unlined water bodies and
recharges into ground water. It is uncertain as to which if any, of the Assessments would be
levied by Watermaster under these circumstances.
Both the intermediate and shallow zone well fields, as described in the Proposed Plan, will
extract ground water from the Main San Gabriel Basin. Therefore, the Main San Gabriel Basin
Watermaster could impose the Replacement Water charge. This charge currently is $246.65 per
acre-foot. It probably will increase gradually over the years, because it is indexed to
Metropolitan Water District charges, which are projected to rise in the future.
EPA's Response: The comment correctly points out the need to consider replenishment costs if
ground water is to be extracted. The PVSC's initial draft Feasibility Study did not incorporate
these costs. EPA had subsequent conversations with the Main San Gabriel Basin Watermaster,
and based on those conversations, replenishment water costs would not be incurred as long as the
treated water was discharged/recharged back into \he San Gabriel Basin. The selected remedy
includes discharge of treated water into the surface waters within the PVOU and consequently
within the San Gabriel Basin. Therefore, it is unlikely that replenishment water costs will be
charged as a result of implementation of the selected remedy, and the Watermaster reiterated
their support for implementing remedial actions that extract and treat contaminated ground water.
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City Comment HA: USEPA Region IXshould designate the final landowners and businesses in
the Puente Valley whom it considers potentially responsible parties, and, therefore, liable for
superfund response costs in the PVOU. Region IXshould make these designations well before it
issues the ROD, so that the designated parties have an opportunity to review the Proposed Plan,
have communications with Region IX and the PVSC, and become integrated into negotiations
between the PVSC and Region IXfor an agreement on PVSC implementation of the remedy
adopted in the ROD.
Region IX bases its decisions in designating PRPs on information about individual sites gathered
by the Regional Board. The City and the Agency understand that the Board's staff has finished
its investigations on all but a handful of individual properties. At this point, the City and Agency
believe that it is reasonable and fair for Region IXto make a decision about all individual
properties, with the exception of properties where the responsible business or landowner has
resisted Board requests or orders for investigatory work
CERCLA itself directs USEPA to designate PRPs at a federal superfund site before it issues the
ROD for the site. 42 U.S. C Section 9613 (k)(2). This directive establishes a fair procedure
because it assures that the parties whom the USEPA believes should pay the superfund costs
have a chance to review and comment on the proposed superfund remedy before USEPA adopts
it. In addition, this statutory directive fosters implementability of the superfund remedy the ROD
approves because a cooperating group of PRPs, like the PVSC here, is more likely to reach an
agreement to design and build the superfund remedy quickly once it knows all the parties who
are liable to pay for it.
Finally, designating all the PRPs before issuance of the ROD facilitates another USEPA policy,
encouraging early cash out settlements for parties who contributed relatively small amounts of
contamination to the regional pollution problem. Nationally, the USEPA has had a policy of
encouraging early de minimis settlements since at least 1993. Early last year, the Regional
Administrator promised members of Congress that Region IX would encourage similar early
cash out settlements with smaller parties in the San Gabriel Basin superfund sites, including the
PVOU. Exhibit Bpp. 2-3.
As a practical matter, it is difficult for a cooperating PRP group to participate in de minimis
settlement discussions until its members know with substantial certainty the size of the group of
PRPs as a whole and the relative size of the subgroup of PRPs with sufficiently small liability
shares to qualify for cash out settlements. Therefore, USEPA Region IX 's failure to date to
designate the final PRPs for the PVOU is creating a significant obstacle to realizing its own
policy favoring early cash out settlements at superfund sites.
EPA's Response: This is an enforcement issue that does not affect EPA's consideration of
remedial alternatives or selection of a remedial action. EPA expects to complete the
identification of all PRPs for the PVOU within a few months of this ROD. It has taken a number
of years for the Regional Board to investigate the hundreds of current and former industrial and
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commercial facilities in the PVOU that may have used chlorinated solvents and for EPA and the
Regional Board to identify those that are sources of ground water contamination and the entities
that are legally responsible for the contamination.
Section 9613(k)(2) of CERCLA requires EPA to "make reasonable efforts to identify and notify
potentially responsible parties as early as possible before selection of a response action." EPA is
not required to postpone the selection of a response action until all PRPs are identified. EPA
agrees that it is desirable to identify and notify all PRPs as soon as reasonably possible, and
intends to do so for the PVOU.
City Comment IIB: The PRPs must pay for both the superfund remedy, as outlined in the
Proposed Plan, and for the USEPA 'spast investigatory and other response costs allocable to the
PVOU. The Proposed Plan gives a cost estimate for the superfund remedy of $27.8 million.
USEPA Region IX has not, however, given the PVSC or the public its past cost figure to date.
Region IX should release this past cost figure, together with supporting documentation, as soon
as possible, so that it may be considered well before the ROD is issued. Based on past cost
figures for other superfund sites, PVOU'spast costs may approach $10 million, or about one-
third the cost of the entire superfund remedy. Uncertainty about such a significant cost figure
creates an obvious practical obstacle for members of the PVSC and other PRPs interested in
agreeing to fund the superfund remedy to negotiate agreement for the remedy with Region IX
quickly. Moreover, since the past costs need to be factored into the cash out settlements. Region
IX's failure to provide this figure discourages and delays negotiations over these types of
settlements, thereby undermining USEPA's policy favoring early cash outs.
EPA's Response: This is an enforcement issue that does not affect EPA's consideration of
remedial alternatives or selection of a remedial action. EPA intends to provide the PVOU PRPs
with an estimate of past response costs and supporting documentation as soon as this information
is available. EPA will take past costs into consideration if EPA settles with any PRPs.
Response to Suburban Water Systems (SWS) Comment, dated March 13,
1998
SWS Comment: Suburban Water System supports the EPA Alternative 3, Ground-water control
in the shallow and intermediate zones at the mouth of the valley and ground-water monitoring.
EPA's Response: Comment noted.
Response to Central Basin Water Association (CBWA) Comment, dated
February 12,1998
CBWA Comment: The Central Basin Water Association supports USEPA 's Proposed Plan for
the Puente Valley Operable Unit.
10
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The goal ofCBWA with regard to activities at the San Gabriel Superfund Sites is to prevent the
migration of any contaminants above the Maximum Contaminant Level past Whittier Narrows.
Contamination from the Puente Basin has already migrated into the Main San Gabriel Ground
water Basin, requiring that purveyors treat water from affected wells in order to meet drinking
water standards. The Proposed Plan (Alternative 3 of the four alternatives outlined in the
feasibility study) requires extractions and treatment as needed to meet performance criteria for
containing contamination and preventing further migration. This active approach to
remediation will help ensure that contamination does not continue to migrate further into the
Main San Gabriel Basin and past Whittier Narrows into the Central Basin.
EPA's Response: Comment noted.
Responses to Comments from Zevnik, Morton, Guibord, McGovern, Palmer
& Fognani on behalf of Cleveland Pneumatic Corporation (CPC), dated
March 16,1998
CPC Comment 1: The EPA Proposed Plan is based on a Remedial Investigation and
Feasibility Study ("RI/FS") which did not sufficiently determine the location of sources of the
ground water contamination within the site to adequately select a remedy for the site.
Specifically, the plan relies on ground water extraction in the mouth of the valley area for
"containment" of contamination in the PVOU.. However, an assessment of the available data,
most of which is not presented, analysed or otherwise considered in the RI/FS, indicates that
there are major sources ofPCE and TCE contamination in the Puente Valley in areas
upgradient of the mouth of the valley area. Implementation of the Proposed Plan might result in
the significant movement of contamination from these highly contaminated source areas into the
mouth of the valley area where extraction is to occur. Given the high concentration of
contaminates, ground water extraction should only be considered at or near where these major
sources are shown to be present in order to prevent migration into areas of lesser concentration
during the extraction process at the mouth of the valley.
EPA's Response: This comment refers to the presence of numerous areas of high VOC
contamination or "hot spots" upgradient of the proposed remedial action. EPA acknowledges
both the presence of these areas, as well as the need for these areas to be addressed through
aggressive, site-specific remedial actions. EPA's Feasibility Study also notes that EPA fully
expects and supports actions taken under the purview of the Regional Water Quality Control
Board - LA Region (RWQCB), to address these local areas of high concentrations of
contamination in ground water. The regional actions recommended in the proposed plan were
developed assuming that facility-specific actions will continue. The specific actions taken at the
mouth of Puente Valley should be designed in a manner that does not accelerate the spread of
contamination from these hot spots.
CPC Comment 2: The selected remedy for the PVOU does not appear to take into account the
strong probability that the San Jose Creek could operate as a uninterrupted, highly permeable
11
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pathway for VOC migration from sources at the top of the valley to the mid-valley and mouth of
the valley areas. This situation should be investigated further since it was not adequately
addressed in the RI/FSfor the site. If the San Jose Creek is a pathway, then the proposed plan
should include ground water extraction along the creek.
EPA's Response: The potential for the San Jose Creek to "operate as a uninterrupted, highly
permeable pathway for VOC migration" was extensively evaluated during the RI/FS process.
After more than a year of sampling and analysis of migration through the creek, both in surface
water and in the subdrain system, it was concluded that any contaminants migrating along the
subdrain pathway would eventually be captured by remedial actions at the mouth of the valley.
In addition, it was found that significant contaminant transport can only occur during "ideal"
conditions, when the water table intersects the subdrain system for considerable distances.
Volatilization and dilution of VOCs in the surface water occurs very quickly.
Response to Comments from the San Gabriel Valley Water Company
(SGVWC), dated March 11,1998
SG VWC Comments: This letter supplements my statement at the public meeting held
Wednesday, January 28, 1998, at La Puenle High School concerning EPA's proposed plan to
address ground water contamination at the Puente Valley Operable Unit ("PVOU").
As I explained at the public meeting, San Gabriel Valley Water Company ("San Gabriel")
strongly supports EPA's preferred alternative (which is Alternative 3 in the PVOU Final
Feasibility Study Report). Among other things, that alternative favors ground water extractions
at the B7 Well Field as part of the preferred remedial action. It also calls for the PRPs to
negotiate directly with the water purveyors that operate wells in the B7 Well Field in order to
make the existing water supply systems part of the selected remedy. (See generally PVOU Final
Feasibility Study Report at p. 4-5.)
By letter dated October 30, 1997 to Ms. Eugenia Chow, U. S. EPA 's Remedial Project Manager
(copy attached), San Gabriel's President Michael L. Whitehead stated:
"San Gabriel is prepared to meet and confer with the EPA and Puente Valley Steering
Committee to determine how San Gabriel's wells in the B7 Well Field or elsewhere can
be integrated into the preferred remedial action. "
At the January 28public meeting in La Puente, I reiterated that commitment.
In addition, Ms. Carol Williams, Executive Officer of the Main San Gabriel Basin Watermaster,
and representatives from Suburban Water Systems, City of Industry, and the Central Basin Water
Association all endorsed EPA 's preferred alternative. Also, it is significant that representatives
of the Puente Valley Steering Committee in their comments at the public meeting did not object
to EPA 's preferred alternative as it relates to the B7 Well Field. Indeed, no one at the January
28 public meeting opposed EPA 's preferred alternative as it relates to the B7 Well Field.
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EPA's preferred alternative is the product of an exhaustive process, including a remedial
investigation and feasibility study, analysis by EPA's staff and by affected parties, and
recommendation by EPA's Region IXand the National Remedy Review Board. Clearly EPA 's
preferred remedy has broad public support, and I am aware of no opposition to the preferred
alternative as it relates to the B7 Well Field. Accordingly, EPA's preferred alternative should be
adopted as the appropriate remedial action in Puente Valley.
EPA's Response: Comment noted.
Response to Comments from Richard A. Sullivan, dated February 12,1998
Richard A. Sullivan Comment: Thank you for the Region's January fact sheet which solicits
comments from the public on your proposed plan for addressing ground-water contamination by
volatile organic compounds (VOCs) in the Puente Valley. The fact sheet states "These Remedial
Action Objectives (RAOs) reflect EPA's regulatory goal of restoring usable ground waters to
their beneficial uses -- within a time frame that is reasonable, ." .
Preferred Alternative 3 would provide hydraulic control to prevent migration of contamination
in the shallow and intermediate zones beyond the mouth of Puente Valley, and would also rely
on natural attenuation for rehabilitation of ground waters in the zones. Returning ground water
of the 5-mile long VOC -contaminated plume in the shallow zone to its beneficial potable uses by
Alternative 3 would take decades while the dense non-aqueous phase liquids (DNAPLs) would
also continue to migrate downwards and worsen DNAPL contamination in the deeper
intermediate zone plume.
A more expeditious approach to Alternative 3 would be to accelerate rehabilitation of ground
waters in the shallow zone plume by utilizing those existing wells in the zone that are now closed
down because of VOC contamination. Adaptive intermittent pumping rather than conventional
constant pumping from the existing wells would further accelerate removal of DNAPLs from the
shallow zone. The extracted contaminated ground waters would flow through a treatment plant
and then into the community water distribution system. Choice of multiple small plants or a
large plant would depend on pipeline costs to convey water for decontamination treatment and
then distribution. Removal of DNAPLs from the intermediate zone at mid-valley (Alternative 4)
could also be accelerated by adaptive intermittent pumping.
The adaptive intermittent pumping approach accelerates leaching of DNAPLs from the geologic
microenvironment, and the technique is outlined in my article "Pump and Treat and Wait"
published in Civil Engineering magazine of the American Society of Civil Engineers. A reprint
of the article is enclosed. Implementation of the adaptive pumping approach is controlled by the
observational method, which recognizes uncertainty in micro-geologic conditions and chemical
behavior with resulting impact upon the rate of leaching. Enclosed is an outline application of
the observational method.
13
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The intent of my comments to Alternatives 3 & 4 of EPA's proposed plan is to convey some
constructive suggestions that could save time and money in restoring ground waters at Puente
Valley to their beneficial uses within a reasonable time frame.
EPA's Response: The reviewer refers to intermittent pumping and the observational method as
tools that may enhance the effectiveness of the selected remedy. EPA concurs that these
techniques should be considered during remedial design.
Response to Law Offices of Daniel Romano on behalf of Goe Engineering
Company, Incorporated (Goe), dated March 16,1998
Response to Goe comment 1: In 1994, the EPA completed a baseline risk assessment to
evaluate the potential health effects from exposure to contaminated ground water, and to
determine if any remedial actions would be necessary to protect human health or the
environment. As part of the risk assessment the EPA evaluated three scenarios:
1. The potential for a current resident to be exposed to ground water through
domestic use;
2. The potential for a future resident to be exposed to contamination in ground
water through domestic use; and
3. The potential for current and future workers and residents to be exposed to
contamination in ground water through transport ofVOCsfrom ground water through the
foundation of a building.
The EPA uses a "target risk range " of one person in ten thousand to one person in one million
getting cancer from the contamination at the site. Risks that fall within or below this range are
considered acceptable and generally do not require remediation, and risks greater than one in
ten thousand warrant remediation.
The risk assessment of the first scenario, potential for a current resident to be exposed to ground
water through domestic use, resulted in estimated excess lifetime cancer risks within the
acceptable risk range. Even the estimated risks were overly conservative in that blending of
ground water from several production wells and the current ground water treatment by water
purveyors were not considered. Therefore, under the first scenario, no remedial action is
warranted.
The risk assessment of the second scenario, potential for a future resident to be exposed to
contamination in ground water through domestic uses, inexplicably resulted in a total estimated
excess lifetime cancer risk of five in one thousand, which exceeds both the target risk range and
risk to current residents. The risk assessment analysis assumed that future ground water
production wells would be drilled/installed directly within eight areas or plumes that had ground
water concentrations exceeding ten times the MCLs. This assumption is not only overly
conservative, but unrealistic. The EPA has further assumed that ground water extracted by the
water purveyor would not be treated prior to reaching any future consumers. This assumption in
14
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also unrealistic in that it implies not only the conduct of an unreasonable act by the water
purveyor, but to do so would also be illegal. We believe that a reevaluation of this exposure
scenario should be conducted, and that the exposure risks to future residents should be at least
as low as the exposure to current residents, if not lower.
The risk assessment for the third scenario, potential for current and future workers and residents
to be exposed to contamination in ground water through transport of VOCsfrom ground water
through the foundation of a building, determined that the estimated excess lifetime cancer risk to
current and future workers/residents was within the target risk range. The EPA also determined
that there is no threat to plants and wildlife from exposure to contaminated ground water.
Finally, the EPA considers that the principal threat identified in the P YOU is the possibility that
Dense Non-Aqueous Phase Liquids ("DNAPLs ") may be present in the ground water. However,
DNAPLs have not been observed at any of the monitoring wells installed in the PVOU. We
believe that if the possible presence of DNAPLs is suspected at a specific facility, confirmation
and/or removal of this threat should be the responsibility of that specific facility. Even assuming
that DNAPLs exist, regional ground water extraction in the PVOU, as proposed by the EPA, may
actually remobilize any possibly existing DNAPL layer and adversely impact deeper
uncontaminated aquifers.
EPA Response: This comment refers to overly conservative assumptions and the existence of
institutional controls as a mechanism for preventing human exposure to contaminated ground
water, and the recommendation that the baseline risk assessment be conducted with that
assumption in place. EPA disagrees that the baseline risk assessment is the proper place to take
institutional controls into account. The role of the baseline risk assessment is to address the risk
associated with a site in the absence of any remedial action or control, including institutional
controls. The baseline assessment is essentially an evaluation of the no-action alternative.
Institutional controls, while not actively cleaning up the contamination at the site can control
exposure and, therefore, are considered to be limited action alternatives. The effectiveness of the
institutional controls in controlling risk may appropriately be considered in evaluating the
effectiveness of a particular remedial alternative, but not as part of the baseline risk assessment.
For the VOC contamination in ground water at the PVOU, the concept of "principal threat" does
not apply, therefore it is not included in this Interim ROD.
Goe Comment II: The EPA considered several remedial alternatives to reduce the risk from
potential exposure to the contaminated ground water. The considered alternatives included:
1. No action
2. Ground water monitoring of the shallow, intermediate and deep zones at the
mouth of the Puente Valley and at mid-valley.
3. Ground water control in the shallow and intermediate zones at the mouth of the
Puente Valley and ground water monitoring (the EPA 's preferred alternative).
4. Ground water control in the shallow and intermediate zones at the mouth of the
15
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Figures
SCO/9B2670004.DOC/1-97
-------
Alhambra
BALDWIN
PARK
Azusa
I
PUENTE VALLEY
OPERABLE UNIT
Hacienda
Heights
Figure 1
Vicinity Map
Puente Valley Operable Unit
'I Ul '.(i Ous Pi >< '( in
-------
Figure 2
1997 Shallow VOC Contamination
Puente Valley Operable Unit
-------
Figure 3
1997 Intermediate VOC Contamination
Puente Valley Operable Unit
Ovo ..f.--.fi,««r.*. f..i^-
^*ri. j N»T * .'i In ',-
-------
ALTERNATIVE
1 (No Action)
2 (Groundwater
Monitoring)
3 (Mouth
Extraction)
4 (Mouth and
Mid-Valley
Extraction)
o
o
o
o
o
o
o
o
N/A
N/A
N/A
C-S2.244
NPW-$7,778
C-$8,276
NPW-S27.798
C-$11,751
NPW-$36,869
o
o
N/A - Not Applicable; no actions implemented
Low
Medium
High
NPW - Net Present Worth, 5%; 30 yrs
o
o
Figure 4
Qualitative Criteria
Evaluation Matrix
Puente Valley Operable Unit
SCO109991.0801 MslniFh 9/98
-------
Puente Valley and in the intermediate zone a mid-valley and ground water monitoring.
The primary flaw in the EPA's evaluation/development of the above remedial alternatives is the
fact that neither the current nor planned site-specific remedial actions being conducted within
the PVOU have been taken into account. Throughout the PVOU, several facilities, under the
purview of the RWQCB, have been taking and continue to take remedial actions to treat
contaminated ground water beneath and/or downgradient of their respective facilities. As
correctly described in the FS report:
"ftjhese activities have resulted in, and will continue to contribute to, a reduction in
existing contamination. Moreover, some of the existing activities (e.g., at the
BDP/Carrier site) may serve to reduce contaminant migration within portions of the
PVOU. "
The BDP/Carrier site has operated a ground water extraction and treatment system since August
1986, presently pumping at a rate of approximately 500 gallons per minute (gpm). Other
facilities currently conducting or planning to conduct, ground water extraction and treatment
include the TRW/Monadnock, TRW/Benchmark, Spectral Electronics^ Ajax and the Lansco Die
Casting facility.
In addition, source control actions to remediate VOCs within subsurface soils have been
undertaken at several facilities, including the Goej'Physicians facility. The RAP for the
Goe/Physicians facility has been approved by the RWQCB, and is currently being implemented
and is designed to not only remove the soil contaminants but also remove any future threat to
ground water from the site. Additional source control have been completed or planned at
several other facilities, including: BDP/Carrier, TRW/Benchmark, TRW/Monadnock, Spectral
Electronics, Lansco Die Casting, Utility Trailer, and Acorn Engineering. The FS report itself
indicates that "ftjhe importance of these source-specific actions is that they have the potential to
remove additional VOC mass from both ground water and the unsaturated zone. "
We strongly believe that the remedial alternatives considered by the EPA are incomplete and
intrinsically flawed because they do not consider the effects of the current and planned site-
specific actions being taken to remediate both soil and ground water within the PVOU. The EPA
has spent substantial efforts to perform ground water fate and transport models to predict VOC
contamination plumes behavior in response to their proposed alternatives. The modelling effort
did not take into consideration the negative effects that ground water extraction and treatment at
the mouth of the Puente Valley would have on the site-specific ground water extraction and
treatment systems being conducted within the valley. For example, EPA 's proposed ground
water extraction at the mouth of the valley would cause "hot spots" (areas of high VOC
concentration), currently located beneath source sites, to migrate into less contaminated
downgradient areas and away from the capture zone of existing site-specific ground water
remediation systems. It is our opinion that these "hot spots " can best be remediated by the
existing site-specific extraction systems. In addition, ifDNAPL layers are present beneath any of
these facilities, EPA 's proposed ground water extraction program may remobilize the DNAPLs
into less contaminated areas of the aquifer and/or deep aquifers.
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EPA's Response: EPA recognizes that source control actions are occurring and agrees that these
actions could reduce contaminant migration in portions of the PVOU. However, the data
collected during and after the Remedial Investigation (RI) indicate that existing source control
actions were not adequately containing contaminant migration. The PVSC specifically avoided
the inclusion of parcel-specific source control actions in the development of remedial alternatives
(See Puente Valley Operable Unit Interim RI/FS Comment/Response Summary, Final Feasibility
Summary, Camp Dresser and McKee Inc. (July 1996), p. 12). The RI/FS therefore did not
develop sufficient information for EPA to determine whether additional source control actions
could be used as part of a CERCLA remedy to contain contaminant migration throughout the
shallow and intermediate ground water. Nevertheless, if source control actions prove effective in
controlling contaminant migration in portions of the PVOU, EPA's performance-based remedy
would not require the responsible parties to develop additional unnecessary ground-water
extraction facilities. EPA agrees that actions taken at the mouth of Puente Valley should be
designed in a manner that does not accelerate the spread of contamination from these hot spots.
Goe Comment III: Based upon the above facts, we believe that the EPA should develop a
ground water model for the PVOU which takes into account consideration the effects that site-
specific remedial actions will have in the overall reduction ofVOC mass from both soil and
ground water and to reduce contaminant migration. Such a realistic model would provide the
necessary data to allow the EPA to consider new remedial alternatives that would effectively
address the EPA's Remedial Action Objectives ("RAOs")for the PVOU.
It is very likely that when the effects of site-specific remedial actions are properly evaluated, new
cost-effective remedial alternatives could be developed which meet the EPA 's RAOsfor the
Puente Valley. Therefore, Goe would recommend the continue evaluation of the existing site-
specific remediation systems and their effect on the contaminant migration of the claimed deep-
water aquifer plume, prior to the expenditure of nearly $30 million (or more) for the
implementation of the EPA's proposed alternative. In the interim, and evan after a period of
continued evaluation, there is no risk to human health because the water purveyors are required
to treat the ground water prior to making it available to consumers.
The site-specific soil and ground water remediation systems should likely be effective in
remediating the highly contaminated areas within the shallow ground water zone both in the
mouth of the valley and at mid-valley locations. If, based upon the new ground water model,
contaminant migration in the shallow zone at the mouth of the valley is not adequately
contained, then re-injection of ground water treated by the site-specific treatment systems within
the mouth of the valley (i.e., TRW/Benchmark site) could be incorporated at selected locations to
properly contain the downgradient migration into water supply wells. Similarly, re-injection of
ground water, treated by site-specific systems within the mid-valley area (i.e., BDP/Carrier),
along Hacienda Boulevard into the intermediate zone should prevent the downgradient
migration of VOCs in the intermediate zone into the mouth of the valley areas.
Similar remedial alternatives, which incorporate and compliment current site-specific
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remediation systems, could be developed and implemented at significantly lower costs than
EPA 's preferred alternative.
EPA's Response: This comment refers to consideration of site-specific cleanups of "hot spot"
contamination being conducted by individual facilities. See EPA responses to Goe Comment II
above, and City comment 1D.
Response to Royall K. Brown Comments, dated March 12,1998
Royall K. Brown Comment: The EPAs Preferred Alternative #3 has two basic shortcomings.
First it cost to [sic] much and there is a cheaper version of clean up that has not been presented
to the public for comment. Second Alternative 3 does not provide for compensation to the water
ratepayers of Upper San Gabriel Basin who have has {sic] to pay for the clean up of water from
Puente Valley Operable Unit before it is delivered to them by water retailers.
Since the referenced maps show no pollution in the shallow zone of Puente Valley at the Sunset
Drinking Water Wells (B7 Well Field) and there is VOC contamination in the Deep zone along
N. Sunset I conclude the outflow from the shallow zone of the Puente Valley Operable unit is
discharging by hydraulic pressure to the deep zone as a result of the heavy pumping of the
Sunset Well Field as noted by the Puente Basin Watermaster 1994 and commented upon in the
second paragraph of page 5-3 of the Final Remedial Investigation Report by the Puente Valley
technical [sic] Committee and is image 266 of 283 in your Data Base. As long as Sunset
Drinking Water Wells are heavily pumped it is my opinion that there is not threat that any
contaminated water from the Puente Valley Operable Unit will get to Whittier Narrows and exit
Upper Basin to contaminate the lower basins (Central and West).
Based upon the above noted conclusions I propose an improvement upon Alternative #3. This
improvement is to provide an incentive for the Principle [sic] Responsible Parties (PRPs) to
achieve a quick clean up of Puente Valley O.erable [sic] Unit to avoid the high cost of a
centralized collection system at the Mouth of Puente Valley. I suggest the utilization of well
head treatment. Inorder [sic] to correct for the shortcommings [sic] of Alternative #3, as noted
above, the PRPs wil have to pay of [sic] all the past and future costs of cleaning up of drinking
water wells in the N. Sunset Well Field. Next all of the PRPs at thier [sic] own properties will
have to deafer all contaminated extraction wells on thier [sic] sites on a weekly basis in all
zones for as long as there is any contamination in Puente Valley.
If after a reasonable period of years the dewatering of the contaminated extraction wells by the
PRPs does not prevent reoccurance [sic] of contaminations of the wells in the N. Sunset Well
field, the EPA should then impose Alternative #3 as a corrective measure.
I must note there are low cost extraction methods at low yield contaminated extractions [sic]
wells the PRPs could use; such as compressed air pumping with on site collections in tanks and
transport by truck to treatment facilities. Using trucks instead of high cost collection with high
sunk cost piping will greatly reduce the PRPs investment in corrective equipment that Alternative
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#3 includes.
Next I need to point out that the current level of extractions by PRPs is not addequate [sic] to
clean up the contamination. Image 48 of 283 of your data base from the technical [sic] committe
notes the 1994-95 extraction of contaminated water was only 1067 acre-feet. This is
inaddequate [sic] for a quick clean up of the shallow zone. The PRPs must expand thier [sic]
efforts to extract contaminated water in the Puente Valley Operable Unit. A quick dewatering of
the shallow zone will allow a natural infusion of clean water by natural processes. Clean water
in the shallow zone will result in an inflow to the lower zones and evential [sic] dilution of the
contamination in the deep zone that supplies water to the N. Sunset Drinking Water Well Field.
Also I not the heavy pumping of wells South of the 10 Freeway and East of the 605 Freeway has
caused a pumping depression to occure [sic] in that area. The N. Sunset Well Field is only a
protion [sic] of the historic extractions of water that constitute this pumping hole. As long as
this pumping depression continues the threat of any Puente Valey polluted ground water getting
to Whittier Narrows is eliminated as Puente Basin is a minor source of water to the main Upper
San Gabriel River Basin.
EPA's Response: The reviewer notes a) the absence of mapped contamination in the shallow
zone in the vicinity of the Sunset Drinking Water wells, and b) the effects of deep pumping on
containing contamination. The lack of mapped contamination in this area may primarily reflect a
lack of data from the shallow zone. The effects of deep pumping in the B7 well field are duly
noted in the Feasibility Study. These wells may be considered part of a regional remedial action
if the appropriate assurances can be made on their continued pumping. In the absence of such
assurances, it cannot be assumed that this pumping will indefinitely prevent the migration of
contamination away from the mouth of the Puente Valley.
Response to Glen E. Powell, CPM Comment, dated January 21,1998
Glen E. Powell Comment: Since the pollution of the San Gabriel Valley covers such a large
area, 167 Square Miles, and has been polluted for such a long time, the solution by a
Responsible Government should be as simple and fair to all concerned as possible. Therefore I
am in favor of solution NO. 3.
This solution could be solved in (he following manner, which has now been put into motion with
our aging sewer problem, by assessing every property within this area. Trying to single out any
small group for our present pollution problem is unfair and discriminatory, because of all the
pollution caused by cesspools and septic tanks before the sewer system was installed. Another
source was from all of the dump sites where waste material was hauled from all these properties
and contributed to this present day pollution problem. A lot of this past pollution was caused by
unknowing employees during our war years working for the safety of our Country, for this
Government and on the Instructions of this government. These contracted small and large
Companies employees, while working on Government Contracts during this war time period
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unkowingly contributed to most of this pollution in experiments. This now leaves this pollution
the problem of the present owners of the land and our Government who ordered and sanctioned
this work to save our country. ALL [sic] who have lived in this valley as long as I have (over 51
years) have witnessed all of the above. A reasonable Insurance [sic] plan should be available
to ALL [sic] who work with, manufacture or haul TOXIC [sic] material the same as car
insurance is required before they handle this type of material.
As the world becomes smaller and more interdependent, and our country becomes even more
pluralistic, we have got to find ways to lead by exercising tolerance toward everyone. The Civil
Rights Act was passed in 1964 to insure [sic] these rights. Respect these rights in your decision.
EPA's Response: EPA does not have the legal authority to finance CERCLA (Superfund)
response actions by levying assessments on all property owners. EPA and the Regional Board
have undertaken an extensive investigation of the businesses and other facilities in the San
Gabriel basin (including dump sites) that might have been sources of VOC contamination in the
ground water. Of those facilities that EPA has identified as sources of contamination, EPA has
not singled out any subgroup for cleanup responsibilities. EPA has no evidence that cesspools
and septic tanks are sources of the VOCs that are the subject of the CERCLA response actions in
the PVOU. Businesses that contracted to provide materials and services to the federal
government during war time are not exempt from liability for cleanup costs because their
contamination was not caused by an act of war (See 42 U.S.C. § 9607(b)).
Response to the Puente Valley Steering Committee (PVSC) Comments,
dated March 13,1998
PVSC Initial Comment: PVSC incorporates herein its prior submissions to EPA with respect
to the PVOU, including but not limited to:
I. Summary Report, San Jose Creek, Surface Water/Ground water Interaction (Camp
Dresser & McKee Inc., February 1, 1994).
2. Puente Valley Operable Unit, Interim RI/FS, Draft Remedial Investigation Report and
Appendices (Camp Dresser & McKee Inc., December 12, 1995).
3. Puente Valley Operable Unit, Interim RI/FS, Draft Feasibility Study Report and
Appendices (Camp Dresser & McKee Inc., March 1996).
4. Puente Valley Operable Unit, Interim RI/FS, Comment/Response Summary, /Final
Feasibility Study (Camp Dresser & McKee Inc., July 1996).
5. Letter of April 29, 1997 from Robert M. Walter of TRY to Brett P. Moffatt of EPA re:
Puente Valley Operable Unit, San Gabriel Valley Superfund Site, Analysis of Applicable
and Relevant and Appropriate Requirements ("ARARs").
6. Puente Valley Operable Unit, Interim RI/FS, Final Remedial Investigation Report and
Appendices (Camp Dresser & McKee Inc., May 30, 1997).
7. P VSC Comments on EPA's 5/30/97 PVOU FS, submitted as Attachment A to letter of
August 15, 1997 from Robert M. Walter of TRY to Brett Moffatt of EPA.
8. Comments of the Puente Valley Steering Committee to United States Environmental
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Protection Agency Superfund National Remedy Review Board regarding Puente Valley
Operable Unit, San Gabriel Valley, California, Feasibility Study (October 30, 1997)
(submitted with letter dated October 28, 1997).
To the extent that any of these documents, or any part of them, are not already included in the
administrative record relating to the PVOU, PVSC hereby requests that such document (s) be
included in the record.
EPA Response: EPA has included these documents in the administrative record. Documents 1 -
4 and 6 do not contain "comments" on EPA's proposed plan or the final RI/FS. EPA has
responded to the comments contained in document 8 in its "Responses to Issues Raised by the
Puente Valley Steering Committee for the San Gabriel Valley Superfund Sites, Puente Valley
Operable Unit, City of Industry, CA," November 24,1997, which is included in the
administrative record. The comments contained in document 5 are restated in document 7. EPA
addresses the comments contained in documents 5 and 7 in this Responsiveness Summary.
PVSC Comment 1: Under "Site Description " on page 2, the Proposed Plan states that (a) the
PVOU is within the San Gabriel Valley, (b) ground water in the San Gabriel Valley is
contaminated with VOCs, and © the ground water from San Gabriel Valley flows into the
Central Basin, and "could affect the water supply of the Los Angeles metropolitan area." The
Proposed Plan and ROD should include the clarification that ground water contamination in the
PVOU has never impacted the Central Basin, and is not likely to in the future even if no
CERCLA regional action is implemented.
EPA's Response: In the absence of significant ground-water pumping by production wells
within the San Gabriel Basin, in the vicinity of the mouth of the Puente Valley, ground water
flowing out of the Puente Valley would eventually travel west and southwest towards Whittier
Narrows. This natural flow direction is documented in historical maps of the potentiometric
surface prior to significant pumping in the area.
For the effect of ground-water pumping near the mouth of the valley to be considered appropriate
as a means of containing contamination, these wells would need to be considered part of the
CERCLA remedy. This option is left open in the Record of Decision, as well as in the Proposed
Plan. Unless pumping at these wells is considered part of the CERCLA remedy, it cannot be
assumed that this pumping will continue indefinitely, thus preventing migration of Puente Valley
contamination through Whittier Narrows, and into the Central Basin.
PVSC Comment 2: In the sixth paragraph of "Site Description," it is stated that "All
aquifers...in the PVOU are considered to be municipal water sources...." The Proposed Plan
should mention, however, that the entirety of the shallow zone is non-potable due to
concentrations of total dissolved solids (TDS) and nitrates, compounds unrelated to industrial
activities, which exceed drinking water standards. Also, the Proposed Plan should mention that
existing governmental controls prevent exposure to any contaminated ground water.
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EPA's Response: The data collected to date indicates that portions of the shallow zone are non-
potable without treatment. EPA does not know that the entirety of the shallow zone is non-
potable.
PVSC Comment 3: At the end of "Site Description " it is stated that "Figures 2 and 3 show
1996 VOC concentrations in the shallow and intermediate zones. " In meetings with the PVSC,
EPA has agreed that such depictions represent substantial simplifications of the actual
magnitude and extent of VOC distribution. The figure referenced in this Proposed Plan,
therefore, is misleading and inaccurate. EPA's revised plume maps which were presented in the
January 28 public meeting and based in part on data collected by the PVSC in October and
November 1997 are also misleading, as they were generated using some data that are 5 years
old or older. Furthermore, the deep zone VOC maps rely heavily on inactive production wells
where the VOCsare likely derived from shallow, and not "deep", contamination.
EPA' Response: Figures 2 and 3 in the ROD provide supplemental text explaining that they are
simplified representations of the magnitude and extent of the VOC contamination in the PVOU.
PVSC Comment 4: In its "Assessment of Health Risk" on page 4, EPA concludes that the
calculated risk of 5 x Iff3 for the shallow zone represents "the highest exposure that is
reasonably expected to occur at the site ". This calculated risk, however, assumes installation of
a domestic water supply well beneath privately owned industrial property, and the distribution of
that untreated water to the public for 70 years, both of which are prohibited under existing laws
and regulations. It is inappropriate to (a) state that such prohibited acts are "reasonably
expected to occur," and (b) base calculated risks on portions ofPuente Valley (i.e. beneath
individual facilities) which EPA itself has explicitly stated, in writing, are not to be considered in
the PVOU remedy evaluation process. Furthermore, current concentrations are significantly
below the concentrations used by EPA in their risk assessment due to the on-going remediation
at individual facilities.
EPA's Response: See EPA response to City Comment IE1.
PVSC Comment 5: Further in the "Assessment of Health Risk", EPA states that "The
(emphasis added) principal threat identified in the PVOU is the possibility that DNAPLs are
present in the ground water... ", despite the fact there is no direct evidence that DNAPLs exist
today. EPA itself acknowledges that, at best, data from "some areas suggest the possible
presence of DNAPLs " (emphasis added). Developing a remedy based on the possibility of a
threat is inappropriate.
EPA's Response: For the VOC contamination in ground water at the PVOU, the concept of
"principal threat" does not apply, therefore it is not included in this Interim ROD. The remedy
was not developed to address DNAPLs.
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PVSC Comment 6: In the first full paragraph on page 7, in the introduction to the alternatives
description, EPA states: "EPA considered several alternatives to reduce risk from potential
exposure to the contaminated ground water. " (emphasis added). This statement is made despite
the fact that no quantifiable reasonable risk of exposure currently exists, nor is one expected in
the future. Furthermore, the Plan states that EPA's alternatives are "designedfor migration
control, rather than mass removal." It should be noted that migration control does not reduce
the risk for potential exposure in the PVOU, because no complete exposure pathway exists.
EPA's Response: EPA addressed the analysis of exposure pathways in its response to City
Comment IE1. The PVSC previously agreed with EPA that there are completed exposure
pathways in the PVOU (See Puente Valley Operable Unit Interim RI/FS Comment/Response
Summary, Final Feasibility Summary, Camp Dresser and McKee Inc. (July 1996), p. 14).
The Baseline Risk Assessment found a total estimated excess lifetime cancer risk for potential
future residents of five in one thousand (5xlO~3). This level of risk warrants action at the PVOU.
EPA's selected remedy is an interim action intended to control the spread of contamination.
Although this action will not eliminate the risks posed by ground water upgradient from the
mouth of Puente Valley, it will prevent contamination from migrating to waters that are currently
clean or less contaminated and will therefore limit the extent of ground water contamination
posing unacceptable health risks.
PVSC Comment 7: EPA's cost estimate for Alternative 3 ($27.8 million) does not include the
replenishment costs for extraction of groundwater in the San Gabriel Basin without beneficial
use in the Basin. Although the treated groundwater would be discharged within the San Gabriel
Basin, if the discharge results inflow via surface water outside of the Basin, replenishment costs
may be necessary. Such replenishment costs are currently $245/ac-ft/year, and thus could total
several million dollars over the life of the remedy.
EPA's Response: See EPA Response to City Comment IF.
PVSC Comment 8: In the description of Alternative 3, EPA proposes performance criteria for
the shallow and intermediate zones. The proposed criteria are identical to those proposed by
EPA early in 1997, and do not reflect any of the modifications suggested by the PVSC
representatives in its meeting with EPA on October 3, 1997. The PVSC's suggested changes
include:
Using terminology such as "restrict" instead of "prevent"
Modifying "migrating " with an adverb such as "significantly "
* Removing "possibly "from before "a multiple ofMCLs ", or otherwise affirming the use of
multiple ofMCLs.
Recognizing that the buffer zone may be defined differently for different areas of the mouth of the
P YOU, and should be based on a number of factors including the aquifer characteristics, use of
aquifer, access restrictions, etc.
EPA's Response: EPA has permitted the PVSC to provide substantial input throughout the
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process of developing the performance criteria specified in the ROD. The final performance
criteria reflect the last two changes suggested in this comment. EPA did not adopt the first two
suggested changes because they would create ambiguity in the criteria.
PVSC Comment 9: The description of Alternative 3 continues to imply that the shallow zone
remedy will be a regionally-based action. The data collected by the PVSC in the fall of 1997,
which EPA agreed to incorporate into the Proposed Plan, continue to strongly support the
existence of several shallow plumes rather than a single broad plume as depicted in Figure 2,
which are most appropriately addressed by a combination of facility-specific and sub-regional
actions combined with natural attenuation. This distinction is critical to selecting and designing
a cost-effective remedy. The EPA has supported monitored natural attenuation as a viable
alternative in OSWER Directive 9200.4-17- Use of Monitored Natural Attenuation at Superfund,
RCRA Corrective Action, and Underground Storage Tank Sites (November 1997), in which it is
stated that:
"...its use may be appropriate as a component of the total remedy, that is, either in conjunction
with active remediation or as a follow-up measure."
Moreover, the EPA went on to state that:
"For example, evaluation of a given site may determine that, once the source area and higher
concentration portions of the plume are effectively contained or remediated, lower
concentration portions of the plume could achieve cleanup standards within a few decades
through monitored natural attenuation, if this time frame is comparable to those of the more
aggressive methods evaluated for this site. Also, monitored natural attenuation would more
likely be appropriate if the plume is not expanding, nor threatening downgradient wells or
surface water bodies, and where ample potable water supplies are available. The remedy for
this site could include source control, pump-and-treat system to mitigate only the highly-
contaminated plume areas, and monitored natural attenuation in the lower concentration
portion of the plume. In combination, these methods would maximize ground water restored to
beneficial use in a time frame consistent with future use of the aquifer, while utilizing natural
attenuation processes to reduce the reliance on active remediation methods (and reduce cost). "
The PVSC believes the aforementioned statements support the appropriateness of facility-
specific actions coupled with monitored natural attenuation.
EPA's Response: OSWER Directive 9200.4-17, Use of Monitored Natural Attenuation, is
quoted as a basis for recommending "facility-specific actions coupled with monitored natural
attenuation." The performance-based approach adopted for this operable unit, in addition to
EPA's support of RWQCB-led actions to address contamination at individual facilities and
sources, are consistent with this recommendation. However, it should be noted that the quoted
Directive specifically states that such an approach is appropriate in conditions where "the plume
is not expanding, nor threatening downgradient wells... [and where] ...ample potable water
supplies are available." The directive also states that under such conditions, the remedy "could
include source control, pump-and-treat system[s] to mitigate only the highly-contaminated plume
areas, and monitored natural attenuation..." The pump-and treat system described in the
Proposed Plan is designed to only address areas of relatively high concentrations in the Shallow
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Zone (greater than 10 times the MCL), and no mention is made of active remedial actions in
areas of lower concentrations. Nonetheless, it is reiterated that the performance-based approach
allows for flexibility in the selection of specific remedial activities.
PVSC Comment 10: On pages 3 and 4 ofEPA's document entitled "Response to Issues Raised
By The Puente Valley Steering Committee For San Gabriel Superfund Site, Puente Valley
Operable Unit, City of Industry, CA " (November 24, 1997), EPA expresses concerns regarding
the PVSC's use of contaminant transport modelling. Specifically, EPA states that "Although it is
typically necessary to make simplifying assumptions of this type in building numerical models, it
must be clearly understood that at some scales the model cannot accurately predict the behavior
of the natural system." The PVSC acknowledges the uncertainties inherent to any modelling.
However, contaminant transport models are widely accepted tools to be used in concert with all
field data to assist in predicting the future distribution ofVOCs. At no time has the PVSC used
the model at a scale where the model would be inaccurate. All models must be refined by both
performing sensitivity analysis and collecting/analysing new data -where gaps exist. As EPA has
acknowledged, the PVSC has performed both of these refinements, and will continue to do so as
new data become available.
Furthermore, EPA notes that "measurement of migration across an individual facility at the
mouth of Puente Valley supports transport velocities of an order of magnitude greater than those
predicted by the model. " It should be noted that (a) throughout the entire PVOU, there is only
one small geographic area where the model may have underestimated flow rate, (b) the
underestimate is considerably less than "an order of magnitude ", © the underestimate occurs in
the flow model and thus would affect particle tracking simulations as well as estimates of the
contaminant transport, and (d) such underestimates have been resolved by the collection of
additional data, which the PVSC has completed.
In summary, .the PVSC believes that transport modelling is an essential tool to be used to assist
in the interpretation of existing data and provide reasonable prediction of future VOC
distribution.
EPA's Response: Comments regarding uncertainties associated with transport modeling, and
the PVSC's efforts to use these tools appropriately are noted.
PVSC Comment 11: On page 5 ofEPA's November 24 document, EPA noted that the PVSC's
detailed documentation of the occurrence of natural attenuation relied on "the results of facility-
specific activities ". This is a true statement. However, EPA also states that the use of these data
"was inconsistent with the limitation of the scope of the RI/FS ". Yet, EPA's Risk Assessment for
the PVOU is wholly based on these facility-specific data. As noted in comment No. 4 above,
EPA then extrapolated these data into an unrealistic exposure scenario that violates applicable
regulations, upon which the proposed remedy selection is partially based. We do not understand
how the facility-specific data can be rejected as inconsistent with the scope of the RI/FS on one
hand, and be a significant factor in remedy selection on the other.
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EPA's Response: The comment notes that EPA suggested that facility-specific data are
inappropriate for assessments of natural attenuation, yet were used by EPA in the Preliminary
Baseline Risk Assessment. It is inappropriate to only consider conditions at individual sites,
when assessing the potential role of natural attenuation in addressing the regional spread of
contamination. Site-specific data were considered in the risk assessment, as a means of assessing
the potential effects of contaminants in water ingested by the general public in areas of high
concentrations. This approach is consistent with EPA risk assessment guidance.
PVSC Comment 12: On page 6 of EPA's November 24 document, EPA states that Suburban
Water Systems (SWS) discontinued use of their Mid-Valley Wells because of the presence of
VOCs. It is a matter of the public record that the inactive status of these wells was not due to
VOCs. but rather the result of nitrate and TDS concentrations which no longer were at
"manageable levels."
Furthermore, on this page EPA cites the recent proposal of Rowland Water District to install a
water supply well in the PVOU as proof that "ground water in the Puente Basin may therefore
soon become a source of drinking water in the PVOU". EPA neglects to mention that (a) the
proposed well would be completed in deeper zones where contamination is minimal, and not the
shallow zone, where both the PVSC and EPA are concerned about TDS, nitrate, and VOC
concentrations, (b) if the well were installed, it would be equipped with treatment capability,
hence there would be no exposure pathway, and © EPA itself has already rejected Rowland's
proposal for well installation.
EPA's Response: The comment states that the Suburban (SWS) wells within the Puente Valley
were shut down because of nitrate and TDS concentrations rather than because of the presence of
VOCs. EPA has received conflicting information regarding the reason these wells were shut
down. One source involved with the shut-down of these wells suggested that the nitrate and TDS
values were indeed manageable if the wells were operated in an intermittent fashion to
accommodate peak demands, because of the ability of the purveyor to blend the water in the
system. However, when high VOC levels were detected, it was no longer feasible to look at
blending as an option to meet drinking water standards.
The comment also refers to EPA's suggestion that the recent proposal of Rowland Water District
to install a water supply well in the PVOU suggests the potential for Puente Valley ground water
to be considered as a future source of water supply. It should be noted that although the
proposed well would indeed be completed in deeper, relatively uncontaminated zones, and that it
would include a treatment system, the fact that this proposal underscores the value of this water
supply remains. The statement that EPA has rejected Rowland's proposal for well installation is
incorrect.
PVSC Comment 13: On the matrix evaluation of Alternatives (page 5), EPA states that
Alternative 2 "does not meet the criterion " for four of the evaluation criteria. As commented
previously to EPA, the alleged failure to meet the criteria is predicated on the fact that EPA
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assumed in evaluating Alternative 2 the illegal delivery of contaminated drinking water to the
general public. The P VSC asserts that a legitimate monitoring alternative should not be based
on illegal actions.
EPA's Response: Alternative 2 consists of ground-water monitoring. This alternative does not
meet four of the CERCLA evaluation criteria (overall protectiveness; compliance with ARARs;
long-term effectiveness and permanence; reduction of toxicity, mobility or volume through
treatment) because it fails to prevent the continued spread of ground-water contamination.
In its evaluation of alternatives, EPA did not assume the illegal delivery of contaminated
drinking water to the general public. Instead, EPA considered the ability of each alternative to
control the migration and use of contaminated ground water. Since Alternative 2 does not
provide for ground-water extraction or well head treatment, this particular action would not limit
the extraction, distribution and use of contaminated ground water. Nevertheless, EPA's
assumptions regarding the existence or absence of regulatory requirements on the use of
contaminated ground water do not affect EPA's determination that Alternative 2 would not
adequately control contaminant migration.
PVSC Comment 14: In the description of Alternative 2, EPA states that it "does not have any
ground water containment, extraction, treatment, conveyance, or discharge components." This
statement is inaccurate. EPA's Alternative 2 includes the continued extraction and conveyance
(without the current treatment) of ground water from the intermediate zone by the B7 wellfield,
which EPA later acknowledges would indeed "provide containment of the intermediate zone at
the mouth of the valley. " Therefore, Alternative 2 does, in fact, include active ground water
containment and extraction.
EPA's Response: Although the technical evaluations of Alternative 2 in EPA's Feasibility Study
consider the effects of regional ground water extraction in the "B7 well field," the costs of this
extraction and required treatment are not considered. As explained in the Feasibility Study,
regional ground water pumping is considered in hydraulic evaluations of ground water flow
because it is an essential and dominant factor affecting the direction and velocity of ground water
movement. However, because Alternative 2 does not consider this extraction to be part of the
specific remedy, the costs for actually undertaking this extraction are not considered.
EPA Response to PVSC Comments on EPA's 5/30/97 PVOU FS
"(Attachment A)" Incorporated by Reference into Comments on the
Proposed Plan
PVSC Attachment A Comment 1: Section 1.1 - EPA's text states "...the development of
alternatives for remedial action to address shallow groundwater contamination that should be
addressed through parcel- or source-specific actions are not goals of this RI/FS. " This is
inconsistent with the remedial alternatives developed by EPA in Section 4 that include shallow
groundwater remedies.
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EPA's Response: The RI/FS did not address parcel-specific contamination. These source
control actions are under the purview of the RWQCB. The remedial alternatives developed by
EPA in Section 4 address regional shallow ground water contamination, which is consistent with
the goals of the RI/FS.
PVSC Attachment A Comment 2: Section 1.1.3 - Same comment as above.
EPA's Response: Same as response above.
PVSC Attachment A, Comment 3: Section 1.2, end of second paragraph - EPA adds the
sentence "In addition, while some of the releases may have taken place years, if not decades in
the past, the potential exists that such releases continue at this time." The PVSC's July 1996 FS
had stated, with EPA's concurrence, that "The PVSC is aware of no evidence nor have any data
been collected during this RI/FS to suggest that releases are continuing." EPA's statement is
misleading and inconsistent with data gathered during the RI, which found no evidence that
releases are still occurring. No risk from potential ongoing releases was quantified in the EPA
risk assessment, which also lacked evidence of ongoing releases. This statement should be
deleted.
EPA's Response: Many of the industrial and commercial activities that caused the release of
VOC contamination are continuing in the PVOU. EPA has evidence that releases from some
facilities may have occurred as recently as the 1990s. The potential for future releases of VOCs
to the ground water still exists.
PVSC Attachment A, Comment 4: Section 1.2.4 - Most of the last two paragraphs of the
P VSC's Section 1.2.4 have been deleted. These paragraphs described the poor water quality and
corresponding lack of domestic use ofgroundwater in Puente Basin, and also described
Watermaster Rule 28 and the effectiveness of existing wells and institutional controls in
providing plume migration control. At least some of the deleted text appears to have been relied
upon in Section 4. The deleted information describes existing conditions in the PVOU and is
relevant to analysis of remedial alternatives.
This section omits all text stating that groundwater in the Puente Basin has high concentrations
of TDS and nitrates, which, coupled with poor aquifer yields, largely deters present and future
use of the groundwater for potable supply. The discussion in this section should include the fact
that the limited amount of groundwater extracted in the Puente Basin is used for irrigation only,
and is not suitable for human consumption because of high nitrates and TDS.
The resulting text also completely omits information about both existing and potential additional
Watermaster actions and institutional controls that have been used, and/or could reasonably be
expected to be used, to control migration. This section should include a description of the
Watermaster system of water use controls, which effectively precludes private domestic wells
both in the PVOU and in the Main San Gabriel Valley, and limits the production of groundwater
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for potable uses to regulated public water supply systems. It should also include a discussion of
the containment of ground-water that is occurring as a result of the operation of the "57"
\vellfield by water purveyors, and the water management objectives ofWatermaster Rule 28.
This information is relevant to the identification of pathways of risk, remediation goals, and
remedial action objectives. The lack of this information makes the subsequent identification of
domestic consumption as the pathway of risk (Section 3.1.2.3) misleading, in so far as it implies
that there are or may be pathways other than through a limited number of public water supply
systems.
EPA's Response: The State of California has identified the ground water in the PVOU as a
source of drinking water. In addition, not all PVOU ground water has high levels of nitrate and
total dissolved solids (TDS) or poor aquifer yields that deter its use as drinking water. Puente
Basin ground water has been used as drinking water in the past.
EPA included a discussion of the Main San Gabriel Valley Watermaster regulations and other
exposure-control mechanisms in section 1.5.2 of the FS. These institutional controls are not
relevant for identifying risk pathways, remediation goals or remedial action objectives. See EPA
responses to City Comment IE1 and Goe Comment I. EPA does not assume the effectiveness of
institutional controls when assessing site risks or evaluating remedial alternatives against the "no-
action" alternative.
EPA discussed B7 well field pumping in the FS and included the effects of this pumping in the
development and analysis of the remedial alternatives.
PVSC Attachment A, Comment 5: Section 1.3 - EPA's text refers to a target completion date of
May 1997 for the final RI report. The text should be changed to refer to the actual submittal
date of May 30, 1997.
EPA's Response: Comment noted.
PVSC Attachment A, Comment 6: Section 1.3.1 - Starting at the top of page 1-14 with
"However, similar materials...", the concept of laterally extensive shallow, intermediate, and
deep groundwater zones is introduced. The text suggests more extensive laterally-transmissive
layers and less vertical confinement than was described in the FS prepared by PVSC. However,
the FS does conclude that there is not a great difference in hydraulic conductivity between the
alluvium and the non-water bearing bedrock. A discussion has been added regarding the
relative hydraulic conductivity of the shallow, intermediate, and deep aquifers. A range of
hydraulic conductivity for the three aquifers should be provided. Also, these low hydraulic
conductivity values should be compared and contrasted with the typical range of higher
hydraulic conductivity in the more permeable aquifers in the Main San Gabriel Basin.
EPA has deleted much of the discussion on the predominance of fine-grained sediments
throughout the Puente Valley. This discussion should be re-inserted. This is a significant
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feature that affects the quantity and velocity of both groundwater flow and contaminant
transport.
EPA revised the text to speculate that "the deep zone may be correlated" between MW6-62 and
MW6-71. Since this interpretation is inconsistent with the hydraulic heads, is not apparent in
geophysical logs, and is not used in subsequent analyses, this is speculation which should be
deleted.
There is an apparent typo at the beginning of the paragraph which starts "At an upgradient of
mid-valley..." that makes this sentence confusing.
EPA's Response: The revised FS text attempts to underscore the heterogeneity of the alluvial
sediments, and to explain that the three "aquifers" have been identified as a means of simplifying
the natural system for analytical and numerical purposes. Discussions of their properties would
suggest a better defined layering than is the case. The discussion of relative hydraulic
conductivity clearly demonstrates the finer grained nature of the Puente Valley sediments
compared to those of the Main San Gabriel Basin. Typo noted.
PVSC Attachment A, Comment 7: Section 1.3.4- The PVSC's third bullet (regarding subdrain
flow with supporting calculations) has been eliminated and compressed into a weaker single
sentence at the end of EPA's second bullet. EPA has deleted calculations that support the
statement that the flow through the subdrain is relatively less than the discharge to the
weepholes. The subdrain flow calculations and analysis should be retained to support the
conclusions.
The PVSC's last bullet (regarding VOC migration in the subdrain) has been revised. The change
in wording assumes the need for a remedy. This speculation, which is not supported by field
data, should either be deleted or qualified.
EPA's Response: Revisions to this section were made for the purpose of simplifying the
discussion, and to focus on the issues pertinent to the FS.
PVSC Attachment A, Comment 8: Section 1.4.1.1 - EPA has deleted in its entirety PVSC's
discussion of ground water concentrations that have decreased by orders of magnitude where
facility-specific remedial action under the purview of the RWQCB has been and is occurring.
This discussion should be re-inserted.
EPA's Response: For the purposes of simplification and to focus technical discussions on
matters pertinent to the objectives of the FS, sections of earlier versions of the FS were removed
or modified. Comment noted.
PVSC Attachment A, Comment 9: Section 1.4.1.1 - EPA's "shallowgroundwater"discussion
is based on data from facility wells that are part of the EPA database but were not a specific
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component ofPVSC's RI scope of work. This changes the concept of the "shallow groundwater
being addressed by RWQCB" to say that regional groundwater "includes all groundwater
contamination that has migrated off site of facilities ". This shift in focus pervades EPA's FS and
means that the current FS is attempting to develop remedies and recommendations where no
data has been developed to support them. It is arbitrary and capricious to expand the FS beyond
the scope of the RI data.
EPA's Response: EPA did not change the concept of shallow ground water.
PVSC Attachment A, Comment 10: Section 1.4.1.1 - EPA's reference to Table 1-2 on page 1-
19 is incorrect. The reference apparently should be to Table 1-11, which is a new table. This
table is incorrect, because of the inclusion of shallow facility wells in the east valley as being in
the intermediate and deep zones, rather than the shallow zone.
EPA's Response: Comment noted.
PVSC Attachment A, Comment 11: Section 1.4.1.1 states "As the result of downward
hydraulic gradients and available pathways, VOCs have also spread to the intermediate zone
and portions of the deep zone in Puente Valley." No evidence exists for available pathways.
EPA uses downward gradients as the sole basis for asserting vertical migration occurs, and
ignores all other data. Additionally, the ground water model, which EPA agrees is a reasonable
representation of the hydrostratigraphic environment, shows that little or no vertical leakage
occurs.
EPA's Response: The ground water model is a gross simplification of the natural system. The
layering in the Puente Valley is not well defined. It is more reasonable to assume that low-
conductivity layers are not continuous than to assume there are no pathways. Other mechanisms
for contaminant migration into the intermediate and deep zones include the introduction of
DNAPLs that may have sunk into these horizons because of their specific gravity.
PVSC Attachment A, Comment 12: Section 1.4.1.1 states "...it appears that most of the
contamination detected in the production wells is emanating from the intermediate zone." Also
stated several paragraphs later is "... VOC concentrations from production wells are likely a
combination of higher concentrations from the intermediate zone and nondetect concentrations
from the deep zone." There is no mention of the potential for annular leakage from a shallow
zone source. Additionally, given the high flux from the Main San Gabriel Basin, compared with
the relatively low contribution from Puente Basin, the known concentrations in the intermediate
zone do not seem sufficiently elevated to produce the concentrations seen in the production wells.
EPA's Response: Hypothetical sources of contamination in production wells discussed in the FS
are consistent with observed conditions.
PVSC Attachment A, Comment 13: Section 1.4.1.1 - For the intermediate zone, EPA describes
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the extent ofVOC contamination in the "Mouth of Valley", "Mid-/Central Valley", and "East
Valley" areas. EPA did not produce a plume map for the intermediate or deep zones, but rather
created separate figures for PCE and TCE values in "wells screened across multiple zones"
(Figures 1-16 and 1-17) where the concentrations are posted. EPA's modelling (Appendix B)
does have a Figure B-9 which shows a "deep" VOC contamination plume, but PVSC believes this
is in what EPA describes as the intermediate zone in the FS text. This should be clarified.
EPA's Response: Comment noted.
PVSC Attachment A, Comment 14: Section 1.4.1.1 - In discussing the intermediate zone
contamination at the mouth of the valley, EPA includes a new section "PCE and TCE
Concentrations Versus Time at Mouth of Valley Production Wells" that references Figures 1-18
through 1-25. Figures 1-18 and 1-19 are incorrectly referred to on page 1-26 as "Figures II
and 12". The table in the middle of page 1-22 shows the average 1995 PCE concentrations in
three production wells, including BUB and ETC. PCE is shown as "ND", which does not
appear to be in agreement with Figures 1-18 and 1-20 and text on page 1-26 that describes PCE
concentrations in these wells as having "generally increased from the early 1980s to the mid
1990s." EPA's interpretation of the data shown on these figures implies that there are
continuing increases in PCE concentration, but since the late 1980s this does not appear to be
the case for well B7C. PCE data for well B11B appears to be relatively stable since about 1993.
EPA's interpreted increasing trend in TCE and PCE concentrations may be an artifact of
improved analytical methods and/or sample collection techniques since the early 1980s, when
quantitation limits for these compounds were typically 5 ^g/l. EPA uses inconsistent vertical
scales on Figures 1-18 through 1-25 which make the results misleading. If plots of TCE versus
time in wells B7C andBUB (Figures 1-19 and 1-21, respectively) were plotted on the same
vertical scale used for PCE (Figures 1-18 and 1-20), then it would be apparent that TCE
concentrations in these wells have not been increasing. Furthermore, during the past decade,
VOC concentrations in most of the production wells at the mouth of the valley have exhibited a
steady or decreasing trend.
EPA's Response: Comment noted. The data presented in the FS may be interpreted in a variety
of ways by the reader. The interpretations offered are considered generally consistent with the
data shown.
PVSC Attachment A, Comment 15: Section 1.4.1.1 - The last paragraph on page 1-22 refers to
a non-existent Table 1-3 which may be Table 4-1.
EPA's Response: The comment correctly notes that the reference in the FS to Table 1-3 is
incorrect. The information is contained in Table 4-1 and Figures 1-18 through 1-25 of the FS.
PVSC Attachment A, Comment 16: Section 1.4.1.1 -At the bottom of page 1-23, EPA
inappropriately suggests that the similarity in water quality results in SWS wells is attributable
to the purging methodology; the text is inconsistent with the language that the PVSC and EPA
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agreed to for the Final RI Report and incorrectly refers to the SWS wells as being gravel-packed.
EPA's Response: Comment noted.
PVSC Attachment A, Comment 17: Section 1.4.1.1 - There is considerable confusion
regarding the designation of a "deep" zone in the east valley, the depth of this zone, and, if it
exists, whether it is correctable with "deep" zones in mid-valley and mouth of the valley.
Section 1.4.1.1 appears to show the same high concentrations ofVOCs in the intermediate and
deep zones in the east valley. EPA appears to be relying on the same well data for both zones,
which is not valid.
EPA's Response: See response to next comment.
PVSC Attachment A, Comment 18: For the "deep"zone discussion beginning on page 1-24,
the first sentence refers to two non-existent FS sections. The cited sections are actually in
Appendix E of the PVSC's Final RI Report. Concentrations are only discussed for mid-/central
valley and east valley since no VOCs have been detected in the deep zone in the mouth of the
valley. The wells used by EPA to represent the deep zone in mid-/central valley are MW6-62 and
MW6-71. As stated earlier, the Rldata do not support a correlation of the deep zone between
these two wells. For the east valley, EPA states that the deep zone is monitored by MW6-81 and
"10 facility wells located near San Jose Creek on the north side of the east valley bedrock high."
The PVSC does not believe that these wells should be considered deep. EPA's interpretation of a
deep zone in the east valley is likely incorrect. It is more likely, based on the RI findings, that the
deep zone pinches out near the mid-valley area. At the very least, EPA should reiterate the
relatively shallow depth of the "deep aquifer" in that area.
EPA's Response: EPA agrees that the extent of the deep zone may need tq be expanded further,
however for the purposes of this Interim Action, these differences of interpretation of the East
Valley are not significant.
PVSC Attachment A, Comment 19: Page 1-20, First Bullet - According to the data listed in
Table 1-7, the VOC concentrations at this location are not greater than 100 times MCL as
stated, but between 20 and < 100 times MCLs.
EPA's Response: EPA disagrees with this comment, see Figure 1-10 in the FS.
PVSC Attachment A, Comment 20: The following sections of the FS contain what the PVSC
believes to be incorrect references to east valley facility wells as being "deep" or "intermediate",
rather than "shallow":
Page 1-21, Paragraph 4 - Facility wells in the east valley area should not be considered
as part of the intermediate zone, based on their screened intervals
33
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Page 1-21, Paragraph 7 - The statement that intermediate zone VOC concentrations
generally are higher in the east and mid-valley area is incorrect, because the facility
wells in the east are shallow, not intermediate
Page 1-22, First Table - The east valley monitoring wells, which are I is ted as having
PCE concentrations ofND to over 444 //g/l, are shallow, not intermediate wells
Page 1-24, Paragraph 1 - The 12 facility monitoring wells listed as intermediate wells in
the east valley are shallow monitoring wells
9 Page 1-24, Paragraph 4 - The statement that VOCs have been detected upgradient from
mid-valley is incorrect, because no VOCs were detected in MW6-81 and the 10 facility
wells are shallow wells
Page 1-24, Paragraph 5 - The facility monitoring wells in the east valley should not be
included as part of the deep zone
Page 1-24, Paragraph 6 - Including facility monitoring wells in the east valley as deep
wells is inaccurate
Page 1-25, Paragraph 3 - The statement that elevated levels of VOCs were detected in
the deep zone, based on the concentrations in the facility wells, is incorrect, because
these wells are screened in the shallow zone
Page 1-25, Paragraph 4 - The reported highest PCE concentration of 335 pg/l is from
Ajax well B-19, which is screened from 20 to 40 feet bgs, and the reported highest TCE
concentration of 1,036/ug/l is from Ajax well P-02, which is screened from 40 to 45 feet
bgs. Both of these wells should be considered shallow wells.
Figures 1-26 through 1-36 - These figures are inaccurate, because the facility wells are
actually screened in the shallow zone, and not the intermediate and deep zones
EPA should re-designate all of these referenced wells as shallow, rather than intermediate or
deep.
EPA's Response: Because the layering of the Puente Valley, particularly in its eastern extent, is
so ill-defined, discussions of which horizon individual monitoring wells are completed in are of
little consequence to the overall conclusions of the FS.
PVSC Attachment A, Comment 21: Page 1-22, Paragraph 6 - There is an incorrect citation
for Table 1-3, it does not contain B7 wellfield data.
EPA's Response: Comment noted, see response to PVSC Attachment A, Comment 15.
34
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PVSC Attachment A, Comment 22: Section 1.4.1.3 - Although this section is largely
unchanged from the PVSC FS, the text "Elevated nitrates and TDS have clearly been a
widespread, long-observed problem in the Puente Basin. The source of these constituents has
never been attributed to industrial facilities" has been removed, and replaced with "... seemingly
unrelated to industrial activities in the PVOU...". These changes leave the issue of sources open
for interpretation and omit the well-documented historic context for nitrates and TDS. The
original statement should not have been removed, as the public could erroneously conclude that
the industrial facilities that contributed VOCs are also responsible for elevated nitrate and TDS
concentrations.
EPA's Response: This sentence was reworded to more accurately reflect EPA's level of
knowledge regarding sources of nitrate and TDS contamination in the PVOU. The new sentence
does not imply that industrial activities are known to be a source of nitrate and TDS
contamination.
PVSC Attachment A, Comment 23: Section 1.4.2.1 - The second of two bullets in the middle of
page 1-32 inappropriately deletes the discussion of the four "fates" of VOCs in ground water
that are included in the PVSC's bullet. EPA also deleted the discussion on the likelihood that
facility-specific actions, continued pumping of the B7 wellfield, and natural attenuation may
meet the remedial objectives for the PVOU. This discussion should not be deleted as this
scenario is supported by ground water quality data and contaminant transport analysis.
EPA's Response: EPA deleted the referenced text because there was insufficient data for EPA to
conclude that these potential fates limit the need for an additional regional remedy.
PVSC Attachment A, Comment 24: Section 1.4.3.1 - The last sentence of the second
paragraph of the PVSC's text, which described existing data and modelling as supporting
natural attenuation, has been deleted. The third paragraph is the same as the PVSC's, but
doesn't utilize 1995 data for B7C and B11B which are cited on page 1-22. In the fourth
paragraph, EPA raises the specter of the B7 wellfield wells drawing contamination deeper and
adds the three bullets at the top of page 1-34 that cite negative consequences of "continuing to
permit the VOC contamination to migrate to these production wells". EPA says "continuing to
permit....will have the following effects:", but then for each effect, EPA says it may. There is no
evaluation of actual data, which do not support the likelihood of any of these effects.
Furthermore, EPA's text does not caveat the conclusion that any pumping-induced vertical
migration would (a) be localized, and (b) pumped right back out of the aquifer by the wells.
EPA's Response: EPA believes that the continued migration of VOCs into production wells
would have the effects listed in Section 1.4.3.1 of the FS because of the continued need to treat
large volumes of ground water. EPA agrees that contamination pulled into deeper zones by the
B7 wells could be captured as long as those wells operate at sufficient capacities.
PVSC Attachment A, Comment 25: There is no justification for the language in the first bullet
35
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on page 1-34 that states that response costs may greatly increase if contamination is allowed to
continue to migrate to the B7 wellfield. EPA's speculation appears to be based on an over-
simplistic analysis. Water quality data and contaminant transport analysis support the
likelihood that B7 wellhead treatment costs will not increase without supplemental pump and
treat remedial action. These supporting data and analysis include the observation that VOCs
have not been detected in the deep aquifer in the vicinity of the B7 wellfield; over the past
decade, VOC concentrations in the B7 wellfield have mostly remained steady or exhibited a
decreasing trend; and, contaminant transport modelling indicates that B7 wellhead treatment
costs will not increase without supplemental pump and treat.
EPA's Response: See EPA response to PVSC Attachment A Comments 14 and 24.
PVSC Attachment A, Comment 26: The third bullet says that allowing continued migration of
VOCs to wells B7C and BUB may increase institutional hurdles to implementation of a response
action because of the need to negotiate agreements with the owners of the wells. This seems
contradictory to statements later in the FS that an agreement with the water purveyors would be
an acceptable remedy for intermediate zone control at the mouth of the valley.
EPA's Response: These two statements should not be read as contradictory. The continued
migration of contaminants into the B7C and Bl IB production wells increases institutional
hurdles because the parties implementing the response action would need to reach an agreement
with the well owners to use their facilities as part of the response action. EPA is not opposed to
the negotiation of an agreement to use these facilities.
PVSC Attachment A, Comment 27: Section 1.4.3.3 - PVSC's estimate of 0.25 gpmfor the
discharge across the subdrain has been deleted from the second paragraph. The third
paragraph has been modified, with a new last sentence which says "Contaminated groundwater
in the subdrain system would likely re-enter the aquifer upgradient of the B7 wellfield." EPA's
statement regarding contaminated groundwater in the subdrain re-entering the aquifer
upgradient of the B7 wellfield should be qualified (i.e., contaminated groundwater re-entering
the aquifer would be captured by any of the regional remedial alternatives in this FS) or deleted.
The insignificance of the subdrain in contaminant transport should not be arbitrarily deleted
from this discussion.
EPA's Response: Comment noted. See response to CPC Comment 2.
PVSC Attachment A, Comment 28: Section 1.4.3.5 - Under Adsorption and Desorption. text
was removed that documented low rates ofdesorption compared with sorption. The second part
of the PVSC's paragraph that starts "Contaminants are distributed..." has been deleted. This
original paragraph included a discussion of the slow rate ofdesorption of VOCs from soil and
the importance of adsorption to soil in removing VOC mass from the ground water system.
Despite the text which still says "...as illustrated in examples detailed below...", the last two
paragraphs on page 1-35 of the PVSC's FS that cite PVOU-specific examples and quantification
36
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of retardation have been removed. This inappropriately weakens the natural attenuation
discussion by ignoring the fact that some adsorbed VOC mass is effectively removed from the
system. The deleted text supports the contaminant transport modelling conducted for the PVOU
and should be re-inserted.
EPA's Response: Through the editing process, several sections of earlier versions of the FS
were removed or modified for simplicity, readability, and to focus technical discussions on
matters pertinent to the objectives of the FS.
PVSC Attachment A, Comment 29: Under Decay, the PVSC's conclusion at the end of the first
paragraph that "some decay processes are operating in the PVOU" has been deleted. The
paragraphs near the bottom of page 1-36 of PVSC's FS that cite examples of anaerobic
degradation have also been removed. At the end of the first full paragraph on page 1-38, EPA
adds the sentence "As mentioned previously, the relatively limited occurrence of daughter
products in the PVOU may be the result of discharges of the constituents at the surface, either
directly, or as impurities in other chlorinated VOCs." The examples that EPA removed directly
refuted this conclusion. Not only is data nonexistent to make this statement, it was refuted by the
removed PVSC-presented examples. It is recognized that in most unconfined and highly
permeable aquifers, anaerobic degradation of VOCs is insignificant. However, in the Puente
Valley, the aquifers are mostly fine-grained, locally confined, and have a relatively high total
organic carbon content. Also, as discussed in PVSC's FS, there are locations -where daughter
products are present at concentrations higher than would be expected if these compounds were
impurities. The relative stability of the ground water plume over the last 11 years, as cited
elsewhere in the FS, is another factor consistent with biodegradation of contaminants.
Consequently, anaerobic degradation is likely to occur in Puente Valley; and, the data and
analysis presented in PVSC's FS should not be deleted.
EPA's Response: See response to PVSC Attachment A Comment 28.
PVSC Attachment A, Comment 30: The Summary at the end of this section which states that
"Several natural attenuation mechanisms are documented as operating in the PVOU" has been
deleted. The deletion of discussions regarding natural attenuation appears to be designed to
discount the possibility that not only does natural attenuation occur, it may preclude the need for
additional pump and treat. These selective deletions are misleading to the public and water
community and contrary to EPA's concurrence with the PVSC that natural attenuation is
occurring.
EPA's Response: See response to PVSC Attachment A Comment 28. The FS states that
observations in the PVOU suggest that natural attenuation is a factor in limiting the migration of
VOCs.
PVSC Attachment A, Comment 31: Section 1.5.1 - The portion of this section beginning with
the last paragraph on page 1-39 of PVSC's FS ("A brief overview...") has been deleted. This had
37
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been the list of remedial activities that had taken place at 32 facilities, based on RWQCB
records. Deleting this section ignores the fact that source control actions have lowered
concentrations substantially. Such reductions are the basis for not including a continuous
source term in the modeling simulations. Facility-specific actions have and will continue to
remove more contaminant mass from the system than either of the groundwater pumping
alternatives being considered by EPA. These actions, when combined with natural attenuation
and pumping from the B7 wellfield, are likely to render additional pump and treat unnecessary
to provide adequate containment. Because mass removal by facility-specific actions may play a
very important role in affecting the need for additional pump and treat, and because EPA agrees
that a subregional 1lhot spot" control remedy could be effective for shallow groundwater
remediation, this discussion should not be deleted. In last paragraph of the remaining text, Ajax
should be added as one of the facilities using SVE and/or excavation for source control actions.
EPA's Response: This comment appears to contradict the PVSC's earlier position that Section
1.5.1 was included in the FS as "background information only," and was not intended to support
the incorporation of source control actions into remedial alternatives (Puente Valley Operable
Unit Interim RI/FS Comment/Response Summary, Final Feasibility Summary, Camp Dresser and
McKee Inc. (July 1996), p. 12). The deleted text did not include the quantitative information that
is necessary for EPA to evaluate the effectiveness of source control actions in containing
contaminant migration.
EPA agrees that source control actions in the PVOU remove VOC mass from the shallow zone
and therefore may affect the need for additional ground-water extraction. Accordingly, the ROD
allows the responsible parties to use source controls actions to help achieve the containment
requirements established by the performance criteria.
PVSC Attachment A, Comment 32: Section 1.5.2 - The second sentence has been deleted. This
had referred to the effectiveness of governmental controls and use restrictions. All of Section
1.5.2.1 starting with the last line on page 1-42 of PVSC's FS has been deleted. This had
described how governmental controls limit or make exposure pathways incomplete. The first
paragraph of Section 1.5.2.2 (Judicially Established and Enforceable Use Restrictions) was
deleted, which again had discussed the limited exposure pathways that exist because of use
restrictions. Additional sentences that were dele ted from this section are "Similar controls are
available to the Puente Basin Water master, although they have been unnecessary since no
extracted groundwater from the Puente Basin is used for drinking water" and "Water master
analyzes the submitted data to develop an overall Basin Water Quality Plan which is submitted
to the Regional Water Quality Control Board." Appendix J (Watermaster Rule 28) is not
included in EPA's FS.
EPA's FS omits the discussion that appears in PVSC's FS explaining the unique water use
controls in the PVOU that limit the potential pathways of exposure. The omission is inconsistent
with EPA's Superfund Administrative Reforms, which urge the use of realistic land use
scenarios. The FS also omits PVSC's discussion of wellhead treatment and blending practices,
38
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which, consistent with the Safe Drinking Water Act, have protected the public from exposure to
contaminants in excess ofMCLs.
EPA's Response: EPA deleted the draft text because the description of exposure pathways was
misleading (see EPA Response to City Comment IE1), the inclusion of hypothetical institutional
controls was not relevant to the discussion of existing exposure control mechanisms, and the
salient points from the deleted text are covered elsewhere in the FS. Watermaster Rule 28 is
discussed in Section 1.5.2.2.
The final text is consistent with current EPA guidance which advises that EPA use realistic
assumptions when considering future land use scenarios. EPA expects that most of the land in
and around the PVOU will continue to be used for residential, commercial and industrial uses
and these uses will continue to depend on local water supplies. EPA also expects that ground
water at the mouth of Puente Valley will continue to be used for domestic purposes and
additional drinking water wells may be placed elsewhere within the PVOU in the future.
PVSC Attachment A, Comment 33: Section 1.6- This section has been completely re-written.
It repeats generalized, pre-RI conclusions of the Baseline Risk Assessment (BRA), but deletes
PVSC's application of the findings of the RIto the conclusions of the BRA. The BRA calculated
the excess cancer risk from residential exposure to contaminated groundwater in active
production wells (even though there are institutional controls to prevent consumption of this
water). Since the results were within the acceptable risk range and no valid complete exposure
pathway has been identified, no RME has been established at an unacceptable level for any
receptor. This section also fails to note that the BRA was broader in scope than the Rl/FS and
that, accordingly, not all the general conclusions of the BRA are relevant to the FS. The RMEs
of the BRA are not applicable to the only medium of concern addressed in the RI, regional
groundwater. PVSC's discussions in Section 1.6 of its FS should be-re-inserted.
EPA's Response: The referenced text criticized the Baseline Risk Assessment for using shallow
ground water data as the basis for evaluating human health risks and for failing to assume the
effectiveness of institutional controls. The draft text incorrectly assumed that the RI/FS was
concerned only with regional deep ground water and that institutional controls should have been
considered in evaluating exposure pathways. See responses to City Comment IE1 and Goe
Comment I.
PVSC Attachment A, Comment 34: Figures - As noted previously, the vertical scale is. not the
same on all figures, which could lead to misinterpretation. For instance, Figure 1-24 for well
147W3 indicates a spike in PCE concentrations in the late 1980s/early 1990s that at first glance
appears significant but is below drinking water standards (max about 4.5 pg/1) and would be a
barely-recognizable blip if graphed on the same scale as some of the other figures.
Figures 1-10 through 1-15 state "Samples older than 5 years not evaluated", but the figures seem
to incorporate old or inaccurate data similar to that used in figures PVSC commented on in the
39
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RI Appendix prepared by EPA.
EPA's Response: Comment noted.
PVSC Attachment A, Comment 35: Section 2.3.1.1 - The first paragraph on page 2-4, which
discusses attaining MCLs and non-zero MCLGs, has been added. This section ignores the
natural unsuitability of the PVOU shallow ground water for use as drinking water, due to high
nitrates and TDS, and low specific yield.
EPA's Response: The State of California considers the ground water in the PVOU to be a source
of drinking water. It is EPA policy to consider the beneficial use of ground water and to protect
against current and future exposures. Ground water is a valuable resource that should be
protected and restored if necessary and practicable. Ground water that is not currently used may
be a drinking water supply in the future. (55 Fed.Reg. 8732).
EPA recognizes that shallow ground water at the mouth of Puente Valley is not currently used for
drinking water, and has therefore established shallow zone containment criteria at ten times the
relevant drinking water standards. In addition, the ROD does not establish chemical-specific
cleanup standards for restoration of the shallow ground water because the remedy is an interim
action to contain contamination.
PVSC Attachment A, Comment 36: Section 3.1.2- Although EPA correctly stated the four
required elements of a remedial action objective (RAO) in Section 3.1.1, it has erred in
identifying them. EPA correctly identifies the first two elements of an RAO for the PVOU-the
contaminants of concern are VOCs, particularly PCE and TCE; and the medium of concern is
regional groundwater. The final two elements of an RAO are exposure pathway(s) and
remediation goals(s). The latter element, remediation goal(s), as stated correctly in Section
3.1.1, must "establish acceptable exposure levels that are protective of human health and the
environment."
EPA's Response: EPA does not agree that it erred in identifying the four required elements of
the remedial action objectives (RAOs) for the PVOU. See responses to PVSC Attachment A
Comments 37 through 39.
PVSC Attachment A, Comment 37: Section 3.1.2.3 - EPA identifies domestic use of drinking
water as the pathway of exposure. PVSC agrees that this is the relevant potential pathway of
exposure. Unlike other areas of the country, (hough, this pathway cannot be randomly accessed
through private residential wells. The pathway is limited to a water supply system maintained by
regulated water purveyors.
EPA's Response: EPA agrees that ground water in the PVOU can be legally accessed only by
certain entities holding water rights.
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PVSC Attachment A, Comment 38: Section 3.1.2.4 - EPA attempts to identify remediation
goals. However, each goal is flawed by its failure either to specify an acceptable exposure level
or, because material risk only arises from exposure, to connect a specific acceptable exposure
level to an identified, realistic risk specific to this OU. Some goals are further flawed by
including elements that do not belong in a remediation goal. The table below analyzes goals:
No.
Remediation Goal
Specified
Acceptable
Exposure
Identified
Risk
Comment
1.
"Preventing exposure of the
public to contaminated
groundwater including but not
limited to, attaining MCLs for
VOCs measured at the point of
compliance."
MCLsfor
VOCs
None
Generalized statement that represents
SDWA policy. "[MJeasured at the point
of compliance" is inappropriate for a
remediation goal, which measures con-
centrations at the point of exposure.
"Inhibiting contaminant
migration from more highly
contaminated portions of the
aquifer to less contaminated
areas or depths of the
aquifer."
None
None
This if a description of a remedial activity
rather than a remediation goal.
"Reducing the impact of
continued contaminant
migration on down-gradient
water supply wells."
None
None
The water supply wells are not themselves
a point of exposure to unacceptable risk.
"Protecting future uses of less
contaminated and uncontami-
nated areas and depths of the
aquifer."
None
None
This is a policy statement rather than a
remediation goal as defined by the NCP.
"Initiating efforts designed to
attain MCLs and MCLGs that
are relevant and appropriate
within the P VOU."
None.
None.
This is not an exposure-specific goal. The
determination of whether any MCLs or
MCLGs are relevant and appropriate for
this site is part of the process of identify-
ing ARARs under NCP §300.400(g). They
may be action-specific only, e.g., if
extracted groundwater is furnished for
domestic consumption. For a permanent
remedy, they may be chemical-specific.
However, for this interim remedy, they
cannot be chemical-specific ARARs appli-
cable in the medium of concern. See
§2.3.1.1.
Remediation goals are defined in the Federal Register as follows: "Remediation goals are a
subset of remedial action objectives and consist of medium-specific or operable unit-specific
chemical concentrations that are protective of human health and the environment and serve as
goals for remedial action." 55 Fed. Reg. 8712-13.
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EPA's Response: Remediation goals establish acceptable exposure levels that are protective of
human health and the environment. EPA uses health-based ARARs to set remediation goals,
when they are available. 40 C.F.R. § 300.430(e)(2)(I). Since this is an interim containment
remedy, the FS did not develop remediation goals for ground-water restoration (e.g. MCLs for
ground water). The FS instead developed preliminary remediation goals that address potential
impacts of contamination on the public and on uncontaminated and less contaminated drinking
water.
This comment correctly notes that three of the remediation goals do not specify acceptable
exposure levels. Remediation goals 1 and 5 specified MCLs and MCLGs as remediation
standards. The determination of final remediation goals is made based on the balancing of the
nine evaluation criteria during the remedy selection process. After completing the FS, EPA
reconfigured the remediation goals for the proposed plan (specifying MCLs and a potential
multiple of MCLs), then identified the final remediation goals for the ROD (MCLs/MCLGs and
ten times MCLs/MCLGs). The PVSC provided substantial input into this process. The final
remediation goals are the chemical-specific standards used in the RQD's performance criteria.
The NCP does not require that each remediation goal state a connection between a specific
exposure level and an identified, realistic risk specific to the PVOU. Read in context, it should
be clear that the remediation goals are based on the human health risks posed by the contami-
nated ground water.
PVSC Attachment A, Comment 39: In Section 3.1.2.5, EPA identifies RAOs. Since a proper
remediation goal is a necessary element of an RAO, EPA's error in Section 3.1.2.4 infects this
section with error. EPA's RAOs, furthermore, fail to specify all four elements under NCP
§300.430(d)(2). The following table analyzes the RAOs:
RAO
"Prevent exposure of the
public to contaminated
groundwater"
"Inhibit contaminant mi-
gration from the more
highly contaminated por-
tions of the aquifer to the
less contaminated areas
or depths"*
"fTJo reduce the impact
of continued contaminant
migration on
downgradient water sup-
ply wells. "*
Specified
Contami-
nant of
Concern
None
Hone
Hone
Specified
Medium of
Concern
Ground-
water
None
None
Specified
Exposure
Pathway
None
None
None
Specified
Remedia-
tion Goal
RG#1
RG#2
RGH3
Comment
Merely reiterates RG #1,
which is itself a deficient
RG.
Merely reiterates RG#2,
which is itself a deficient
RG.
Merely reiterates RG#3,
which is itself a deficient
RG.
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"[T]o protect future uses
of less contaminated and
uncontaminated areas. "*
None
None
None
ROM
Merely reiterates RG#4
which is itself a deficient
RG.
/"* These RAOs are grouped in one bullet point in §3.1.2.5]
EPA itself has noted that "[rjemedial action objectives include both a contaminant level and an
exposure route recognizing that protectiveness may be achieved by reducing exposure as well as
reducing contaminant levels." 55 Fed. Reg. 8713.
EPA's Response: Section 3.1.2.1 of the FS identifies VOCs as the contaminants of concern.
Section 3.1.2.2 identifies ground water as the medium of concern. Section 3.1.2.3 identifies
domestic use of drinking water as the most significant potential exposure pathway. Section
3.1.2.3 identifies the remediation goals, which are discussed in EPA's response to PVSC
Attachment A Comment 38, abdve. The RAOs incorporate each of these elements, they need not
restate them.
EPA agrees that in appropriate circumstances, RAOs may be achieved by reducing exposure, as
well as contaminant levels. The determination as to whether exposure controls are the best
method for meeting RAOs is made during the nine criteria evaluation of remedial alternatives.
PVSC Attachment A, Comment 40: In Section 3.1.2.5 the FS also mis-characterizes as a
"regulatory goal" the NCP's listing of restoration of ground water to beneficial uses as a
program expectation. As stated in the NCP, the program expectations are used in developing
remedial action objectives. 40 CFR §300.430(a)(l)(iii). But EPA's general expectation to
restore ground waters to their beneficial uses does not supersede the requirements of the NCP
for the development of proper remediation goals and remedial action objectives. See, National
Remedy Review Board advisory letter re Jack's Creek Site, September 6, 1996. "The fact that a
proposed remedy may be consistent with the expectations does not constitute sufficient grounds
for the selection of that remedial alternative." NCP, Preamble, 55 Fed. Reg. 8702. For this
interim RI/FS, this program expectation has, appropriately, not even been used in developing
remedial action alternatives, none of which attempt to restore ground water to beneficial uses.
EPA's Response: This comment refers to EPA's quotation of Section 300.430(a)(l)(iii)(F) of
the NCP, which states that EPA expects to "return usable ground waters to their beneficial uses
wherever practicable, within a time frame that is reasonable" or if restoration is deemed
impracticable, to "prevent further migration of the plume, prevent exposure to the contaminated
ground water, and evaluate further risk reduction." The reference to this expectation in Section
3.1.2.5 of the FS helps place the RAOs in context with the general goals, management principles
and expectations articulated in the NCP. The preamble to the NCP provides that these expecta-
tions "should be considered when making site-specific determinations of the maximum extent to
which permanent solutions and treatment can be practicably utilized in a cost-effective manner."
55 Fed.Reg. 8701. EPA has used the quoted expectation as guidance, not as a basis for selecting
the remedy.
PVSC Attachment A, Comment 41: EPA's RAOs are inappropriate. The Statement of Work
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authorized the PVSC to develop RAOs pursuant to the NCP. The preamble to the 1990 NCP
provides that "remedial action objectives aimed at protecting human health and the environment
should specify: (1) The contaminants of concern, (2) exposure routes and receptors, and (3) an
acceptable contaminant level or range of levels for each exposure medium. Remedial action
objectives include both a contaminant and an exposure route recognizing that protectiveness
may be achieved by reducing exposure as -well as reducing contaminant levels. " 55 Fed. Reg.
8712-13. EPA has failed to recognize the existing limitations on exposure pathways in the
EPA 's RA Os do not specify accurate exposure pathways.
EPA's Response: See EPA's responses to PVSC Attachment A Comment 39 and City
Comment IE 1.
PVSC Attachment A, Comment 42: Section 3.1.2.4 - MCLs are applicable "at the tap. " MCLs
are also often considered relevant for ground water that is a current or potential source of
drinking water. However, MCLs are not appropriate for the PVOUfor several reasons. First,
the regulated medium for MCLs ("piped drinking water") and the affected medium at the site
(ground water) are different. Similarly, the place regulated (service connections to a public
water system) is much different from the place affected in the PVOU (in-situ ground water).
Further, MCLs are not appropriate because much of the impacted ground water in the PVOU is
unsuitable for direct drinking water use due to elevated levels of nitrates and TDS. EPA 's
CERCLA Compliance With Other Laws Manual (OSWER Dir. 9234.1-01, Aug 1988, p. 1-5)
recognizes that "MCLs are generally not appropriate where ground water is not potentially
drinkable due to widespread naturally occurring contamination. " Manual at p. 1-69. If MCLs
for VOCs were deemed relevant and appropriate for the PVOU, then much of the in-situ water
would still exceed acceptable drinking water standards for nitrates and TDS. The Manual also
recognizes that "MCLs are generally not appropriate for site-specific circumstances where a
well would never be placed and ground water would thus never be consumed. " Id. Similarly,
MCLs are also not appropriate where a regulatory system exists that prevents the extraction and
distribution of untreated drinking water. This is precisely the case in the PVOU. The strict
access restrictions established by the adjudications and the implementing rules of the
Watermaster prevent the unauthorized extraction and use of the ground water.
EPA's Response: MCLs (and non-zero MCLGs) are applicable or relevant and appropriate
(ARARs) for ground water that is extracted and used for domestic, municipal, industrial or
agricultural purposes or discharged into the environment. Since this is an interim remedial
action, EPA has not established final chemical-specific cleanup standards for contaminated in-
situ ground water. However, MCLs and non-zero MCLGs are also relevant and appropriate for
uncontaminated ground water that is that is located downgradient from the remedial action
facilities that are expected to contain contamination in the intermediate zone (See CERCLA
Compliance with Other Laws Manual, Part I (Interim Final), OSWER Directive 9234. 1 -0 1
(USEPA1988),p. 1-8).
The concentrations of nitrates and TDS in the ground water do not affect the use of MCLs (and
non-zero MCLGs) as cleanup standards for ground water that is extracted and used or discharged
by this remedial action. See the response to PVSC Attachment A comment 4.
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EPA does not agree that MCLs and non-zero MCLGs are inappropriate as treatment and
containment standards for sources of drinking water simply because state and federal law
prohibits the service of contaminated water. This is essentially a circular argument which
proposes that it is not necessary to clean up the contaminated ground water under CERCLA
because water purveyors, who have the right to use the water but did not cause the contamina-
tion, are required to remove the contaminants if they choose to exercise their water rights. The
existence of these regulatory controls and their application to production wells in the PVOU, in
fact, demonstrates that MCLs and non-zero MCLGs are relevant and appropriate for the
contaminated ground water.
PVSC Attachment A, Comment 43: The text on page 3-3 introduces the concept ofaqu(fer
restoration ("EPA's regulatory goal at all contaminated ground water sites...") and mass
removal ("The remedial objectives do include "mass removal" as a secondary objective "). This,
to the PVSC's knowledge, is the first time EPA has ever mentioned mass removal for this OU.
EPA had previously agreed that mass removal was not a goal of the interim remedy.
EPA's Response: EPA is required to develop interim remedial action alternatives that are
consistent with the expected final remedial action (40 C.F.R. § 300.430(a)(l)(ii)(B)). VOC mass
removal is identified as a "secondary objective" because containment remedies that accelerate
ground water restoration are most consistent with the objectives that EPA expects to evaluate for
a final remedial action. Mass removal also satisfies one of the NCP's nine remedial alternative
evaluation criteria (reduction of toxicity, mobility or volume through treatment).
PVSC Attachment A, Comment 44: Section 3.1.3 - Reasons Not to Delay Action - This is a
new section added by EPA. EPA states that delaying action would increase the potential for
human exposure. Assuming that a delay in action would increase the potential for human
exposure assumes that there is current exposure, which is incorrect. There is no real current or
future threat to human health from the VOCs in ground water in the PVOU. EPA's assertion is
inconsistent with existing restrictions on water use (e.g. the Safe Drinking Water Act and the
Watermaster system). In other areas, where unrestricted access to ground water exists, this
statement might be more appropriate. The statement also ignores the contaminant transport
modelling in Appendix A, which shows no substantial migration of contaminants under a variety
of assumptions. If the additional modelling that was omitted is considered, it is apparent that
action (i.e., migration control) does not significantly change either the extent or concentration of
contaminants in the PVOU as compared with inaction. This statement also fails to consider the
non-potability of ground water in the PVOU due to TDS and nitrates, which have deterred its
use for other than irrigation.
EPA's Response: EPA has addressed the issue of exposure pathways and the potability of
ground water in its responses to City Comment IE1, Goe Comment I, PVSC Comment 4 and
PVSC Attachment A Comments 4, 32 and 42. EPA does not believe that the contaminant
transport modelling omitted from the final FS demonstrates that migration is not occurring,
especially in light of ground water data which provides more direct evidence of contaminant
migration.
PVSC Attachment A, Comment 45: EPA states that delaying action will increase the burden
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of responding to the contamination on water purveyors. This statement is unsupported by the Rl.
This statement is contradicted by data, referenced in Section 1.4.2.1 ofPVSC's FS but omitted
here, that show that wellhead treatment costs will not increase in the absence of an EPA-
imposedpump and treat remedy. In any event, the shifting of burdens is not an appropriate
consideration when determining whether action ought to be taken under CERCLA. Allocation of
burdens should not be confused with threats to human health and the environment. In contrast,
after action is determined to be necessary at a site, EPA may appropriately consider imposing
the burden of action on responsible parties. In other words, the maxim "let the polluter pay" is
not itself a reason for a response, but is a reason for allocating the burden of an otherwise
appropriate response.
EPA's Response: The data shows that without containment, VOCs are expected to continue
migrating into the B7 Well Field Area. See EPA's response to PVSC Attachment A Comment
44, above. EPA has decided to take action in the PVOU because of contaminant migration, not
because water purveyors are currently paying for ground-water treatment.
PVSC Attachment A, Comment 46: EPA states that delaying action will increase the likeli-
hood for contaminant concentrations to increase in production wells, resulting in the purveyors
responding with actions inconsistent with long-term remediation goals. These statements are
inconsistent with collected data and analysis, assume San Gabriel Valley Water Company and
Suburban Water Systems will not comply with Watermaster Rule 28, and, as such, is misleading
to the public and water community. It should also be noted that no long-term remediation goals
have been established.
EPA's Response: See EPA's response to PVSC Attachment A Comment 44. Watermaster Rule
28 provides that water purveyors must obtain Watermaster approval to locate, modify and
operate production wells, so that ground water contamination is not exacerbated. Rule 28 does
not require that production wells in the San Gabriel Valley be operated to maximize ground-
water containment or cleanup objectives. It also does not guarantee that the San Gabriel Valley
Water Company and Suburban Water Systems would not abandon some or all of the B7 wells if
contaminant concentrations or operating costs increased.
PVSC Attachment A, Comment 47: EPA states that delaying action will increase the extent of
contamination and consequently increase the cost, difficulty, and time required to contain
contamination or restore the aquifer. The RI data and the modelling do not support this
statement. The wording is objectionable because it assumes continued migration (expansion of
the plume), when it has not been demonstrated that this is occurring. Remaining and omitted
text in Section 1.4.3.5 demonstrates that the sorbedphase may well act as a mass sink, due to
higher adsorption rates compared with desorption rates, which is the opposite of what is stated
here by EPA. This statement also assumes that a final RI/FS will lead to a ROD that calls for
containment or restoration of the aquifer, which is an unwarranted assumption.
EPA's Response: Data collected to date indicate that contamination is migrating therefore
delaying the action will increase the extent of contamination and consequently increase costs,
difficulty, and time required to contain contamination. EPA expects that it will eventually
evaluate the need for a final remedial action to restore PVOU ground water. See 40 C.F.R. §
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300.430(l)(a)(iii)(F). Whether or not an action is ultimately taken to achieve ground-water
restoration, EPA should evaluate interim actions alternatives for their consistency with antici-
pated final remedial action objectives. 40 C.F.R. § 300.430(1 )(a)(ii).
PVSC Attachment A, Comment 48: References to Figures 3-1 and 3-2 remain in the text,
despite the figures having been removed.
EPA's Response: Comment noted, the Figures are found in the draft FS prepared by COM (July
1996).
PVSC Attachment A, Comment 49: Section 3.4.1 - EPA's FS re-designates as "Institutional
Controls" what the PVSC's FS called "Control Mechanisms." The change in nomenclature
seems to have affected the substance of the section. PVSC's FS treated "Control Mechanisms" as
a broad category of existing as yell as potential future processes and activities. PVSC believes
that it is consistent with the Superjund Administrative Reforms to identify existing control
mechanisms, including both natural processes and institutional ones^aspart of performing a
realistic appraisal of background conditions. EPA's description of "Institutional Controls " omits
existing processes, such as natural attenuation of contaminants. It also omits reference to many
existing governmental and societal controls that are part of the background conditions at the
site. While such background conditions are not necessarily appropriate for discussion in the FS
section dealing with Technologies and Process Options, they must be recognized at some point
in the RI/FSprocess. The FS, like the BRA, for example, implicitly recognizes some social and
legal background conditions (e.g., it implicitly assumes that local sanitation ordinances, NPDES
andRCRA requirements will be observed), yet assumes that SDWA requirements and
Watermaster use restrictions will not be observed. The unexplained use of different assumptions
is arbitrary.
EPA's Response: EPA disagrees. Institutional controls are not "background conditions." EPA
has discussed institutional controls and natural attenuation in the appropriate sections of the FS.
PVSC Attachment A, Comment 50: Section 3.4.3- EPA deleted PVSC's discussion on
practicality of aquifer restoration, particularly in a fine-grained aquifer. Although EPA states
that aquifer restoration is an ultimate goal, any attempt to restore the Puente Valley aquifers to
pristine conditions would be impractical and fiscally irresponsible. Consequently, PVSC's
discussion should be restored so the public is not misled into thinking EPA or any agency will
pursue aquifer restoration.
EPA's Response: The deleted text contained a short discussion about the difficulties of aquifer
restoration under circumstances that might be relevant to the PVOU. EPA will consider the
practicality of restoring the aquifer when EPA evaluates final remedial action alternatives. There
is no basis, and no need at this time, to conclude that aquifer restoration is "impractical or fiscally
irresponsible."
PVSC Attachment A, Comment 51: Table 3-1 (General Response Actions) was edited to
substitute Institutional Controls for Governmental Controls and Judicially Established and
Enforceable Use Restrictions. Non-CERCLA actions were not included in this. The description
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of the "No Action" alternative does not represent realistic background conditions in the absence
ofCERCLA action. A realistic description should recognize that established Junctions of local,
state and federal government will continue. Otherwise CERCLA remedial action alternatives
must include measures to "CERCLAtize" such basic functions. For example, unless such
functions are recognized in the "No Action" description, CERCLA action must include deputizing
a police force to protect property used in response actions, must order the maintenance of roads
and utilities appurtenant to the response action, must order all inhabitants of the OU to obey
local health and safety ordinances (violation of which would be inconsistent with the CERCLA
response), and must order state and perhaps even other EPA divisions to enforce NPDES and
RCRA requirements. Proper implementation of Superfund Administrative Reforms is impossible
unless the "No Action" alternative recognizes realistic background conditions. In the PVOU,
such conditions include Watermaster use restrictions on ground water andSDWA requirements.
EPA's Response: See EPA's responses to Goe Comment I and PVSC Attachment A, Comment
4. EPA recognizes the operation of institutional controls, they simply are not "background
conditions for the purpose of measuring the effect of remedial alternatives against the No-Action
alternative.
PVSC Attachment A, Comment 52: Table 3-2 - This table uses deficient RAOs to perform
initial screening of remedial technology, but it may be a harmless error in view of the retained
options. However, it improperly attributes responsibility for maintaining existing "institutional
controls " to the P VSC. The referenced mechanisms are part of existing background conditions
that should be recognized in the "No Action " alternative.
EPA's Response: See EPA's response to PVSC Attachment A Comment 39. EPA agrees that
the PVSC cannot control implementation of the institutional controls identified in the FS.
PVSC Attachment A, Comment 53: Section 4.1.1.1.1 - EPA states the RAOs differently than in
Section 3. In Section 3 surface waters are deleted, but they are included here.
EPA's Response: Comment noted. EPA did not find that VOCs in PVOU surface waters posed
a risk to human health.
PVSC Attachment A, Comment 54: Section 4.1.1.2.1 - This section recognizes the containment
of the B7 wellfield, which is inconsistent with other sections of the FS that fail to recognize the
containment benefits of these, wells, but EPA states that there is no assurance that the B7.
wellfield will continue to operate. EPA's assertion that the B7 wellfield may cease to operate is
very unlikely given the following: 1) the water quality data over the past decade and contaminant
transport analysis do not indicate that VOC concentrations will increase to concentrations that
can not be managed with the existing treatment and blending system; 2) the local water demand
is not expected to decline; and, 3) Watermaster Rule 28 which precludes relocating a well to a
"clean" area.
The current pumping at the B7 wellfield is part of the background conditions in the PVOU.
However, the FS does not recognize it as such. Instead, the FS states that "because there is no
assurance that (he production wells will continue to pump into the future to provide containment
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over the life of the CERCLA remedy, this FSdoes not consider the B7 wells to be a potential
component of the CERCLA remedy." The FS states that the current pumping could be used as a
part of a remedy if it is assured by the PVSC. There is no basis for the FS to assume that
pumping of production wells might not continue for the duration of this interim response. No
local planning data or projections of consumption needs are cited to support the assumption.
There is also no basis for insisting on an assumption of responsibility for continued pumping by
PRPs as a condition of recognizing such pumping. It is noted that, in the Pollock OU Site
Assessment [EPA, April 25, 1994], EPA recognized the planned restart of \vellfieldpumping by
the Los Angeles Department of Water and Power as a satisfactory element of meeting migration
control objectives, without insisting on a guarantee, either of the restart or of the continued
pumping, under a CERCLA order or otherwise.
EPA's Response: EPA has consistently recognized that operation of the B7 wells could provide
containment in the intermediate zone. For the effect of ground water pumping to be considered
appropriate as a means of containing contamination, the B7 wells would need to be part of the
CERCLA remedy. This option is left open in the ROD. Unless pumping at these wells is
incorporated into the CERCLA remedy, it cannot be assumed that this pumping will continue
indefinitely.
The statement in the FS that "this FS does not consider the B7 wells to be a potential component
of the CERCLA remedy" might be confusing. For the purpose of assembling and evaluating
remedial alternatives, EPA assumed that new extraction and treatment facilities would be
installed upgradient from the B7 wells. However, the FS, Proposed Plan and ROD all allow for
use of the B7 wells in lieu of new facilities, so long as the B7 wells are part of the CERCLA
remedy and they are achieving the necessary containment. If continued pumping of the B7 wells
is as certain as the PVSC states, it should not be difficult to obtain the assurances necessary to
incorporate the wells into the selected remedy.
PVSC Attachment A, Comment 55: RWQCB-Led Facility Actions are discussed in section
4.1.1.2.2, but only Carrier, Benchmark, and Monadnock are mentioned as pumping ground
water. Facilities such as Ajax, Spectral, Diversey, Lansco, and other facilities which are
considering or actually implementing ground water action are not mentioned. The established
benefits of soil vapor extraction and air sparging on the ground water are not recognized.
EPA's Response: Comment noted. See EPA's responses to City Comment ID and CPC
Comment 1.
PVSC Attachment A, Comment 56: Regarding shallow contamination at the Mouth of the
Valley (Section 4.1.1.3.1) EPA states "The extent and migration rate of VOCs in shallow ground
water downgradient of the mouth of the valley is not well known. Migration velocities and the
extent of shallow contamination should be better defined during RD to determine exactly what
steps should be taken, if any, to meet RAOs in this area." The data should be collected before a
remedy is selected.
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EPA's Response: Some of this information has already been collected and shows that shallow
contamination at the mouth of Puente Valley is migrating. Further information will be collected
during the remedial design.
PVSC Attachment A, Comment 57: In the second and third bullets of Section 4.1.1.3.1, EPA
asserts that vertical migration ofVOC's could occur from one zone to another, due to "down-
ward gradient". These statements regarding downward gradient are repeated throughout
Sections 4 and 5, and are used to justify intermediate zone pumping and an extensive/costly
monitoring program (e.g. see Section 4.1.2.1). However, appropriate caveats, that all existing
data support the hydrostratigraphic factors which greatly minimize the potential for such
vertical migration, are absent and should be added.
EPA's Response: See response to PVSC Attachment A Comment 28.
PVSC Attachment A, Comment 58: EPA states that insufficient data exist on the effectiveness
of natural attenuation. Although the leading edge of the plume has not been characterized,
contaminant transport modelling indicates that natural attenuation will be effective in meeting
the objectives of the PVOU. This should be discussed in this section of the FS.
EPA's Response: Data collected to date indicate that contaminant migration is occurring and
therefore natural attenuation is not containing ground-water contamination.
PVSC Attachment A, Comment 59: Sections 4.1.1.3.2 and 4.1.1.3.4 - EPA states that
contamination may migrate downward from the intermediate aquifer and into the deep aquifer.
EPA's statement appears to be based on overly simplistic analysis that looks only at the
hydraulic gradient. Water quality data, pumping tests, and contaminant transport modelling
indicate that, the aquitard below the intermediate aquifer precludes the downward migration of
significant quantities of contamination. These sections of the FS should include this interpreta-
tion which is based on water quality data and detailed contaminant transport analysis.
EPA's Response: See response to PVSC Attachment A Comment 28.
PVSC Attachment A, Comment 60: For intermediate depth extraction at the mouth of the
valley, although use of the B7 wellfteld is not assumed to be a component of the remedy, it is
stated on page 4-5 that "the extraction at the B7 well field itself could be identified as the
preferred remedial action [for intermediate zone ground water at mouth of the valley] if
continued operation and treatment can be ensured, costs are reasonable, and ongoing monitor-
ing confirms that the well field is effectively meeting RAOs." The PVSC agrees that continued
extraction from the B7 wellfield should be the preferred remedial alternative for intermediate
zone contamination. There are no production wells and therefore no pathways/receptors
upgradient of the B7 wellfield.
EPA's Response: Comment noted. EPA does not agree that there are no pathways/receptors
upgradient of the B7 wellfield.
PVSC Attachment A, Comment 61: Sections 4.1.1.4 and 4.1.1.5 (Evaluation of Ground water
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Extraction During Remedial Design and Predesign Investigation, respectively) appear to offer
some flexibility on pumping locations, rates, and even the need for pump and treat, depending on
the results of a pre-RD investigation. This investigation should be performed before a remedy is
selected.
EPA's Response: Comment noted. See response to City Comment IA.
PVSC Attachment A, Comment 62: In the third bullet of Section 4.1.1.5, EPA states that "The
down gradient extent of this above-MCL contamination in the deep zone needs to be further
evaluated." PVSC is not aware of any legitimate justification to chase VOCs in the 5-10
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also discuss the water rights issues that would have to be resolved for water to be discharged to
Puente Creek and ultimately leave the Main San Gabriel Basin. Costing of any alternatives
involving discharge of water to San Jose Creek should include water replenishment costs. Also,
EPA should discuss what would be required to resolve water rights issues, and the likelihood of
the RWQCB issuing a waiver for discharge to San Jose Creek. Whether EPA would oppose or
override a waiver should also be disclosed. Costing should have been done assuming no waiver.
EPA's Response: See EPA's responses to City Comments 1C and IF. The FS estimated the
costs of nitrate and TDS treatment for the remedial alternatives. EPA addressed the water rights
issues in Sections 4.1.3 and 5.6.1 of the FS and Section 9.6.1 of the ROD.
PVSC Attachment A, Comment 67: Section 4.1.5.4 - EPA states that "... current data suggest
that active ground water control in the mid-valley intermediate zone is likely needed...". To the
contrary, current water quality data and the contaminant transport modelling suggests that
ground water control in the mid-valley intermediate zone is not needed. As discussed above, for
the past decade, water quality data for the B7 wellfield indicates that, VOC concentrations in the
intermediate aquifer are stable or are declining. Also, VOCs are not detected in the deep aquifer
that provides water to the B7 wells. The regional aquitard below the intermediate aquifer
appears to limit the downward migration of significant quantities of VOCs. This is confirmed
with contaminant transport modelling. EPA's assertion is mostly based on an over-simplistic
interpretation that if there is a downward vertical gradient, significant vertical contaminant
migration will occur. EPA's interpretation should be based on the most likely occurrence of
contaminant migration, considering all available data and analyses, not an overly conservative
interpretation of selected data and simplified analysis.
EPA's Response: Active ground-water control in the mid-valley is an element of Alternative 4,
which was not chosen as the preferred alternative.
PVSC Attachment A, Comment 68: EPA's description of No Action (Section 4.2.1) is confus-
ing. It does not consider LARWQCB-ledactions, but "Ground water extraction at water supply
wells is considered as part of background conditions in the PVOU area...". So, it would appear
that pumping of the B 7 wellfield is part of No Action, but it cannot be depended upon to be part
of an active remedy without being CERCLAtized. This should be clarified.
It is inconsistent to consider on-going extraction at the production wells without treatment of the
extracted ground water as part of the "no action " alternative. The "no action " alternative sho uld
recognize the existing situation in the PVOU - absent any intervention by EPA - including
production well pumping and wellhead treatment required by state and local agencies. The
inclusion of existing treatment and monitoring in the "no action" alternative is consistent with
the NCP, which recognizes that the "no action" alternative is "often a 'no further action'
alternative" because of existing action at the site. See, 53 Fed Reg. 51394. "The no-action
alternative involves leaving the site essentially as it is." This is also consistent with EPA's
approach to site characterization, which is performed at the beginning of the RI. The essential
purpose of site characterization is to develop an understanding of the existing features of the
site, including the extent to which ground water is used, or is reasonably expected to be used, as
a drinking water source. Guidance for Conducting Remedial Investigations and Feasibility
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Studies Under CERCLA at 3-7. 3-10 (EPA, Oct. 1988).
EPA's Response: As explained in the FS, regional ground water pumping is considered in
hydraulic evaluations of ground-water flow because it is an essential and dominant factor
affecting the direction and velocity of ground-water movement. As EPA has discussed in its
responses to PVSC Comment 1 and PVSC Attachment A Comment 54, the continued operation
of these wells in a manner that contains contamination is not assured by CERCLA, by this ROD,
or by the parties responsible for implementing the remedy.
Ground-water treatment is not assumed in the No-Action alternative. EPA recognizes that prior
cleanup actions may be part of the baseline conditions that are used for evaluating the No-Action
alternative during subsequent response actions. No-Action alternatives do not include institu-
tional controls and generally do not assume that voluntary activities by others will necessarily
occur in the future.
PVSC Attachment A, Comment 69: Alternative 2 (Ground water Monitoring) "does not have
any extraction, treatment, conveyance, or discharge components." This would appear to exclude
B7 pumping. It is unreasonable to exclude operation of the B7 wellfield. Whether or not an
agreement is negotiated between the PVSC and the water purveyors, the El wellfield will
continue to operate.
EPA's Response: See response to PVSC Attachment A Comment 54.
PVSC Attachment A, Comment 70: Table 4-1, a new table showing information on B7
wellfield wells, contains numerous typographical errors. For example, ground elevation is
shown a "0"for two of the wells, the depths for three wells are incorrect, and the completion
date for five of the wells is shown as "I-Jan-01".
EPA's Response: Comment noted.
PVSC Attachment A, Comment 71: Tables 4-2 through 4-5 are new or substantially revised
tables showing new monitoring wells, existing monitoring wells, components of alternatives, and
extraction information on alternatives, respectively. As noted previously, PVSC believes that
EPA's proposed monitoring requirements are excessive. There is no explanation of footnote A
on Table 4-5, although there is some discussion regarding this (intermediate zone extraction at
Mid-Valley) in the text (page 4-13).
EPA's Response: Comment noted.
PVSC Attachment A, Comment 72: In the first paragraph of Section 5.1.1, EPA make several
statements when describing the "limitations of Alternatives 1 and 2" which are, at best, unsub-
stantiated. These include alleged increased potential for human exposure; increased costs for
VOC treatment; future increases in VOC concentrations (EPA has evidently concluded that
natural attenuation is not occurring and therefore continued plume migration is occurring,
without any data to document this), and increased "time required for... restoration of the
aquifer". Aquifer restoration in a site such as the PVOU is generally considered to be techni-
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cally infeasible. These unfounded statements are part of the basis for EPA's evaluation of the
alternatives and yet they are not based on nor supported by the data generated at great expense
and over long periods in the EPA-sanctioned RI report. This section also fails to take into
consideration relevant existing controls which effectively eliminate exposure pathways.
Alternatives 1 and 2 (if defined properly) meet federal drinking water standards because of
treatment or other actions required to achieve compliance at the tap. An unstated advantage of
Alternatives 1 and 2 is avoidance of the expense of a potentially unnecessary treatment alterna-
tive.
EPA's Response: EPA disagrees. The inability of Alternatives 1 and 2 to control contaminant
migration is well-documented by the RI/FS and the ROD. EPA did not conclude that natural
attenuation is not occurring. Section 1.4.3.5 of the FS states: "Observations in the PVOU ...
suggest that natural attenuation is a factor in limiting the migration of VOCs, both within and out
of the mouth of the Puente Valley toward the Main San Gabriel Basin." EPA cannot assume that
aquifer restoration is infeasible. See EPA's response to PVSC Attachment A Comment 50. EPA
has addressed the issue of institutional controls and exposure pathways in its responses to City
Comment IE1, Goe Comment I and PVSC Comments 6 and 13. Compliance with Safe Drinking
Water Act regulations is not a CERCLA remedial action.
PVSC Attachment A, Comment 73: When Alternative J is properly characterized, it is
apparent that all four alternatives are equally protective of human health and the environment.
The migration control alternatives (3 and 4) do not add protection, because they do not interdict
existing or probable future pathways for the transmission of an unacceptable level of risk to any
sensitive receptors. Furthermore, if one assumes that the FS's "No Action" scenario is valid,
Alternatives 3 and 4 are not protective of human health, because they do not prevent access to
untreated ground water at random points within the PVOU for domestic consumption. Alterna-
tives 3 and 4 must re-invent the Water master system and the SDIVA as elements of CERCLA
action in order to achieve such protection.
EPA's Response: Unlike the No-Action alternative, Alternatives 3 and 4 control contaminant
migration in the ground water and at the pathway of exposure through production wells in the
mouth of Puente Valley. EPA agrees that Alternatives 3 and 4 are not absolutely protective of
human health because contaminated ground water will remain in place upgradient from the
mouth of Puente Valley. The ROD therefore provides that EPA will reassess the selected remedy
every five years. In addition, EPA will evaluate final remedial actions to restore ground-water
quality.
PVSC Attachment A, Comment 74: Section 5.1.2- EPA states that "Alternatives I and 2 ... fail
to provide migration control." This is not true if migration control is occurring due to natural
attenuation, as contaminant transport modelling suggests. Therefore, it is premature to make
this statement. The unwarranted assumption of continued vertical and lateral migration is
pervasive in Section 5. Even assuming that migration control is a valid objective and that there
are actual receptors at risk, placing migration control at mid-valley in the PVOU (as per
Alternative 4) would not protect receptors either upgradient or downgradient, because of the
multiple, facility-specific sources in the valley. Similarly, migration control at the mouth of the
valley (Alternative 3) does not protect anything within the PVOU and would at best be a
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redundant measure in view of the wellhead treatment and blending that is occurring at the B7
wellfield. Modelling shows that natural attenuation is likely to meet the containment objectives.
EPA's Response: Data collected to date indicate that ground-water contamination is migrating
and therefore natural attenuation is not meeting the containment objectives.
PVSC Attachment A, Comment 75: Although the FS states that increasing VOC concentra-
tions are expected at production wells, this is unsupported. Water quality data and contaminant
transport modelling suggest that concentrations in production wells will not increase, and
natural attenuation will preclude wells downgradient of the B7 wellfield from becoming
impacted.
EPA's Response: Modelling is a simplification of actual processes and must be interpreted with
respect to the assumptions made during the modelling effort. Data collected to date indicate that
ground-water contamination is migrating.
PVSC Attachment A, Comment 76: When describing Alternative 4 on page 5-2, it is stated that
this alternative will "remove additional contaminant mass". Mass removal is not previously
identified as an RAO and, in fact, is so noted by EPA on p. 5-10. When evaluating cost, a cost
per pound of mass removed is calculated and it is stated "Although mass removal is not
identified as one of the RAOsfor the Puente Valley FS, it is one of the nine evaluation criteria
(i.e., reduction in toxicity, mobility, or volume through treatment) and is useful in a cost benefit
analysis of alternatives". For this interim FS, mass removal or restoration of the aquifer to
MCLs is not an appropriate consideration. In any event, restoring the Puente Valley aquifer(s)
would be technically impractical and fiscally irresponsible, especially in light of the non-
CERCLA contaminants that render its water non-potable.
EPA's Response: Mass removal is an appropriate consideration under the NCP's nine criteria
evaluation process. See 40 C.F.R. § 300.430(e)(9)(iii)(D). The PVSC has not demonstrated that
restoration of the PVOU ground water is "technically impractical and fiscally irresponsible."
PVSC Attachment A, Comment 77: Section 5.2.1- EPA states that neither Alternatives I nor 2
ensure that water produced from the B7 wells will be treated to reduce contaminant levels to
below MCLs. It is wholly inappropriate to develop and evaluate a monitoring alternative which
violates federal and California law (SDWA, Title 22, etc.). Such a scenario precludes legitimate
evaluation of the alternative under the NCP. This section also ignores the text in Section 2
which states that since this is an interim remedy there are no ARARs. Alternatives I and 2 would
comply with ARARs - the FSjust artificially ignores the ongoing treatment and other actions
which ensure attainment of drinking water standards at the tap. Contrary to the FS, each
alternative satisfies any ARARs that might pertain to it. Alternatives 1 and 2, by definition, do
not have chemical-specific or action-specific ARARs (other than action-specific ARARs related
to monitoring under Alternative 2). Furthermore, since this is an interim FS, attainment of
MCLs or MCLGs is not an objective, as recognized in Section 2.3.1.1, and for the same reason
SWRCB Resolution 92-49 should not be considered. In any event, no alternative seeks to clean
up ground water to any particular level.
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EPA's statement that "Additional restoration of regionally contaminated areas is not consistent
with the RAOs..." is correct. In fact, any restoration is not consistent with the RAOs.
EPA's Response: Alternatives 1 and 2 do not violate state and federal law. Again, as EPA
discussed at length with the PVSC throughout the RI/FS process, the state and federal Safe
Drinking Water Acts and Watermaster regulations are institutional controls that may prevent
exposure to contaminants, but they are not baseline conditions that EPA should assume under the
No-Action scenario. ("Institutional controls, while not actively cleaning up the contamination at
the site can control exposure and, therefore, are considered to be limited action alternatives," 55
Fed.Reg. 8710; see also, 40 C.F.R. § 300.430(a)(l)(iii)(D)). It is not that the alternatives violate
the law, rather, they do not control the ground-water contamination. See EPA's response to
PVSC Comment 13.
The FS does not state that mere are no ARARs. It states that since this is an interim remedy,
drinking water standards will not be ARARs for aquifer restoration.
PVSC Attachment A, Comment 78: Section 5.3- The FS uses deficient RAOs to evaluate long-
term effectiveness. Since migration control is erroneously stated as an RAO, it follows that any
alternative that is not a form of migration control will not satisfy this criterion. All alternatives
are essentially equal in long-term effectiveness when all data are considered and proper RAOs
are used.
EPA's Response: EPA addressed the RAOs issue in its response to PVSC Attachment A,
Comment 39. Actions that control contaminant migration are more effective at reducing risk
over the long-term than actions that allow for continued migration of contaminants into uncon-
taminated ground water and production wells.
PVSC Attachment A, Comment 79: Section 5.3. first paragraph - The in-situ ground water
should not be considered a "waste".
EPA's Response: The contaminants in the ground water are untreated waste.
PVSC Attachment A, Comment 80: In the second paragraph of Section 5.3.1, EPA states that
"particle tracking results suggest Alternatives 1 and 2 do not contain contaminant migration...".
This statement is misleading, given that the particle tracking methodology, by definition, does
not include the hydrochemical processes that would provide contaminant migration control.
This misapplication of particle tracking is used as the basis for rating Alternatives I and 2 as
"low" in Section 5.3.2. The contaminant transport modelling and the water quality data both
show that there is no significant migration of contamination from the shallow aquifer into the
intermediate aquifer, nor is there significant migration of contamination from the intermediate
aquifer to the deep producing aquifer. A hydraulic gradient by itself is no basis to conclude that
there is significant contaminant transport through an aquitard.
EPA's Response: Particle tracking assumes purely advective flow. Comment noted.
PVSC Attachment A, Comment 81: Section 5.4.1 - When the No Action alternative is properly
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characterized, it is apparent that existing background conditions are reducing the toxicity,
mobility, and volume of contaminants. Without additional contamination being added to the
system, natural attenuation will reduce the mobility and volume of contamination. Furthermore,
facility-specific actions, volatilization ofVOCs in ground water that discharges to San Jose
Creek, and pumping of the B7 wellfieldare removing contamination from the system. Again,
EPA's evaluation of alternatives in the FS is contrary to the results of contaminant transport
modelling and reasonable interpretation of water quality data.
EPA's Response: See responses to CPC Comment 1, Goe Comments I and II, and PVSC
Attachment A Comments 4, 31, and 72.
PVSC Attachment A, Comment 82: The analysis which compares mass removal in Alterna-
tives 1 and 2 versus that achieved in Alternatives 3 and 4 is incorrect. EPA calculates the mass
removal by remedial extraction wells assuming 1995 VOC concentrations remain constant for 30
years. These mass removal calculations overestimate the mass removal by not accounting for
the likelihood that VOC concentrations would likely decrease over the next 30 years, especially
given the relatively efficient mass removal attained by facility-specific actions. Any attempt to
perform a mass removal/cost benefit analysis should appropriately consider and include source
control actions. A review of partitioning coefficients for VOCs demonstrates that over 90% of
the VOC mass is in the vadose zone, and that removal of mass from this zone is both more
technically feasible and cost effective than removal of VOC mass from ground water. At least
one industrial facility in the PVOU has already removed more VOC mass with an SVE system
than has been estimated for either Alternative 3 or Alternative 4. Since adsorption is occurring
and is known to permanently remove mass from ground water systems, then a reduction in
mobility and toxicity is occurring with Alternatives 1 and 2.
The criterion of reduction of toxicity, mobility, or volume can only be properly used to compare
alternatives in light of the impact of such reduction (or lack thereof) on the achievement of
RAOs. The deficient RAOs of the FS preclude proper weighing of this criterion.
EPA's Response: The mass removal calculations are included only for comparative purposes,
and are not intended to document absolute removal quantities. The FS notes and supports
facility-specific remediation of contamination in both the unsarurated and shallow saturated
zones.
PVSC Attachment A, Comment 83: Section 5.5.2 - All alternatives are essentially equal in
short-term effectiveness. It is illogical to rank Alternative 1 low in this criterion because it has
no active element. If all alternatives are ranked for short-term effectiveness in light of achieve-
ment of proper RAOs, then all alternatives are also equal.
EPA's Response: In the ROD, Alternative 1 is not evaluated against the short-term effectiveness
criterion. Because the alternatives are not the same, it is illogical that all alternatives should
receive the same ranking with respect to this evaluation criterion.
PVSC Attachment A, Comment 84: Section 5.6.1 - Alternative I is properly not ranked for the
criterion of implementability. Alternative 2 is properly ranked higher than alternatives 3 and 4.
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This section also deals with implementability issues surrounding water rights and discharge
options. The analysis should have conservatively recognized that these may be significant
impediments, rather than the EPA assumption that the issues can be resolved.
EPA's Response: In conversations with the Watermaster, the issues surrounding water rights
have been resolved. The PVSC, RWQCB and EPA identified a process for addressing the issues
surrounding discharge options. On September 14, 1998, the RWQCB approved a resolution
approving EPA's Proposed Plan thereby resolving issues surrounding discharge of treated ground
water.
PVSC Attachment A, Comment 85: Section 5.7 - Given the substantial equality of all
alternatives on other criteria, when properly applied, it is apparent that Alternative 1 is the most
cost-effective alternative for this interim FS.
EPA's Response: Alternative 1 is the most inexpensive alternative; it is not the most cost-
effective because it does not meet EPA's remedial action alternatives, protect human health and
the environment, comply with ARARs, or represent the best balance of the other CERCLA
evaluation criteria.
PVSC Attachment A, Comment 86: Section 5.7.2 - The analysis considers mass removal to be
one of the nine CERCLA evaluation criteria, equating it with reduction in "toxicity, mobility or
volume". This analysis ignores natural attenuation as a mechanism to reduce toxicity and
mobility.
EPA's Response: EPA recognizes that natural attenuation may limit the migration of VOCs and
states so in the FS. Not enough information has been collected to demonstrate significant
reduction of toxicity and mobility as a result of natural attenuation processes.
PVSC Attachment A, Comment 87: Table 5-2 shows mass removed over 30 years. EPA's
estimations appear to be assuming the upper end of the range of existing concentration values
for each area, and also assuming that concentrations will remain constant for 30 years. Neither
assumption is valid.
EPA's Response: See response to PVSC Attachment A Comment 82.
PVSC Attachment A, Comment 88: In Table 5-6 when alternative costs are compared, it is
assumed that water is discharged to San Jose Creek with VOC treatment only, so costs for
treatment of nitrate and TDS are omitted. The present worth and $/lb removed are almost
double ifRO treatment is needed. Cost comparisons should not assume that treatment for TDS
and nitrates will not be required, in view of the statement in Section 4.2.3.3 that such treatment
"wouldprobably be required." While PVSC does not necessarily concur that such treatment
should be required, this statement in the FS requires a corresponding cost estimate in Section 5.
If alternatives involving the discharge of water to San Jose Creek are costed, the costs should
include replenishment costs due to the water not being used beneficially within the San Gabriel
Basin. Lastly, the comparison of Alternatives 3 and 4 in Table 5-7 is misleading, as it does not
compare the mass removal values to the total mass in the subsurface.
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EPA's Response: See EPA's responses to City Comments 1C and IF.
Appendix A
PVSC Attachment A, Comment 89: The references to Well MW6-65 in the last paragraph on
page A2-7 are apparently in error. EPA must be referring to Well MW6-55.
EPA's Response: Comment noted.
PVSC Attachment A, Comment 90: There are significant differences in both Sections 5 and 6
of Appendix A of the EPA FSfrom those in the original FS, as discussed below.
EPA's Response: Comment noted.
PVSC Attachment A, Comment 91: Section A. 5 - The original Section A. 5 included a full
discussion of the Particle Tracking simulations including an assessment of how the results were
in agreement with field observations, and how the model's results supported the conceptual
model, and the postulated contaminant migration pathways. The text addressed how the model's
behavior and results were consistent with the observed distribution of heads and contaminant at
the various screens at MW6-2, 6-3, 6-4 and 6-5. The original text also provided justification for
the results and an assessment of how contaminants might continue to migrate in the shallow,
intermediate (663) and deep aquifer zones in the future.
None of these interpretations of the model's results are included in the EPA version of Appendix
A. 5. The revised text is titled "Particle Tracking Sensitivity Analysis " but it only compares the
results from the steady state and transient simulations - it does not present any real "sensitivity"
analysis as the term is normally used. Comparing particle (plume) capture from 12-year
transient simulations to 100-year containment under steady state conditions does little for the
typical reader, and is no use in the assessment of selected alternatives. The model as originally
applied provided far more insight into plume migration in the Puente Valley OU.
PVSC's Section A. 5 provided a much more cogent assessment of how the overall Puente Valley
hydrogeological system worked, and how the observed distribution of contaminant could be
explained. It made clear what the primary migratory pathways were, and how future plume
movement might occur, or be controlled. It provided the basis on which a logical future decision
could be based. PVSC is concerned that the absence of most of the text assessing the plume
migration characteristics restricts key information from other agencies and the public reviewing
the FS.
EPA's Response: EPA disagrees. PVSC's text and other related documents are available to
other agencies and the public in the Administrative Record
PVSC Attachment A, Comment 92: Section A.6 - EPA's FS omits much of the PVSC FS's
Section A.6 (Contaminant Transport Modelling), and replaces it with particle tracking presented
in Appendix B. The contaminant transport modelling conducted by the PVSC, which has been
accepted by EPA and is included in part of this FS, is much more accurate in predicting
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contaminant fate and transport than the overly simplistic particle tracking used by EPA. The use
of particle tracking by EPA, although useful for estimating ground water flow and well capture,
can significantly overstate contaminant migration. A comparison of EPA'sparticle tracking
results to current water quality data and the results ofPVSC's contaminant transport modelling
indicates that EPA has substantially overestimated the threat of uncontrolled contaminant
transport in Puente Valley (i.e., both at mid-valley and at the mouth of the valley). The 100-year
time horizon used for EPA's particle tracking analysis is extreme and unwarranted for this
interim FS.
EPA's Response: As explained in the FS, simulation of contaminant transport requires numer-
ous assumptions on a wide variety of variable for which there are few data if any data available.
Contaminant transport simulations are also highly dependent on the geometry of the numerical
model, which is a significant simplification of the natural system. As shown in the sensitivity
analysis, even minor changes in assumed parameters greatly affects the results of the contaminant
transport simulations. Particle tracking is more simplistic. The FS uses particle tracking
analyses simply as a method of comparing alternatives and demonstrating well capture. No
implication is made regarding the actual effects of contaminant migration.
PVSC Attachment A, Comment 93: This section has been reduced in scope to only address the
two Alternatives considered by EPA. The reduction in number of Alternatives is consistent with
EPA's different approach to Alternatives considered, but it does remove all the insight gained
from considering other alternatives. Deleting all evaluations of these other alternatives
significantly reduces the knowledge gained from the simulation studies.
EPA's Response: EPA considered the information in this section in preparing the Final FS. This
information is contained in the Draft FS which is part of the Administrative Record.
PVSC Attachment A, Comment 94: As in Section A.5, the section dealing with migratory
pathways and summary of how the modelling results are consistent with field observations has
been deleted.
EPA's Response: See prior response.
PVSC Attachment A, Comment 95: The discussion of mass removal which could be attained
by alternatives has also been deleted. There are tables reflecting the initial mass in the system,
and the mass added during the 30-year simulation period. There are no tables, however,
indicating mass removed from the system (even by facility-specific pumping such as
BDP/Carrier, or discharging to San Jose Creek) during that period of time. The deletion of
these two important conclusions from the section substantially weakens the technical content of
the section.
EPA's Response: See response to PVSC Attachment A Comment 93.
PVSC Attachment A, Comment 96: Most of the technical insight gained during the PVSC's
modelling studies and presented in the original Appendix A. 6 has been inappropriately deleted
from the EPA version.
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EPA's Response: See response to PVSC Attachment A Comment 93.
PVSC Attachment A, Comment 97: Other specific examples of text changes include Section
A.6.5, second paragraph, where PVSC had originally indicated that... "these aquifer zones are
minimally aerobic and not conducive to anaerobic dechlorination...". The revised text deletes
the minimally, and implies that the aquifers are aerobic. This is misleading.
EPA's Response: See EPA response to PVSC Attachment A Comment 28.
PVSC Attachment A, Comment 98: Later in Section A.5.6, the original PVSC text included a
discussion on how the selected retardation factors were consistent with field observations of
plume migration times. All of this text supporting the selected parameters has been deleted from
EPA's document, and weakens the technical basis for the transport simulations.
EPA's Response: See EPA response to PVSC Attachment A Comment 93.
PVSC Attachment A, Comment 99: In PVSC's Section A.6.7.1 PCEMigration, a bullet
discussion addressed the downgradient impact of a DNAPL source in the vicinity ofMW6-4/6-5.
This bullet was inappropriately deleted in total in the EPA document.
EPA's Response: See EPA response to PVSC Attachment A Comment 28.
Appendix B
PVSC Attachment A, Comment 100: Regarding Figures B-20 andB-21 referenced in Section
B. 3.2 for the simulation of Alternative 2, these figures suggest that the B7 wellfield is opera-
tional. Previous descriptions of Alternative 2 appear to exclude B7 wellfield pumping.
EPA's Response: Alternative 2 does include the B7 wellfield pumping.
PVSC Attachment A, Comment 101: Figures B-28, B-29, and B-30 incorrectly refer to
Alternative 6 rather than Alternative 4.
EPA's Response: EPA agrees.
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SAN GABRIEL VALLEY SUPERFUND SITE
PUENTE VALLEY OPERABLE UNIT PROPOSED PLAN
TRANSCRIPT OF COMMUNITY MEETING on San Gabriel
Valley Superfund Site Puente Valley Operable Unit
Proposed Plan held at La Puente High School,
15615 East Nelson Avenue/ La Puente, California,
Wednesday, January 28, 1998, at 7:10 P.M., before
FRANCINE DI GIORGIO, CSR No. 11404.
APPEARANCES:
ELIZABETH ADAMS
U.S. EPA Superfund Division
CATHERINE MC CRACKEN
U.S. EPA Office of Community Involvement
EUGENIA CHOW
U.S. EPA Remedial Project Manager,
Superfund Division
LOREN HENNING
U.S. EPA Remedial Project Manager,
Superfund Division
JON BISHOP
Los Angeles Regional Water Quality
Control Board
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APPEARANCES (Continued.)
BRETT MOFFATT
U.S. EPA Office of Regional Counsel
DR. JACALYN SPISZMAN
Department of Toxic Substances Control
DOUG FRAZER
U.S. EPA Remedial Project Manager,
Superfund Division
BELLA DIZON
U.S. EPA Remedial Project Manager,
Superfund Division
RANDY WITTORP
U.S. EPA Media Relations Office
JON HARRIS
CH2M HILL
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1 LA PUENTE, CALIFORNIA; WEDNESDAY, JANUARY 28, 1998;
2 7:10 P.M.
3
4 MS. ADAMS: Welcome everybody. Thank
5 you for coming and taking the time to be here. We're
6 here basically to talk about the Proposed Plan for
7 Puente Valley, and I just wanted to do some
8 introductions on folks that will be here and doing
9 either questions and answers or 'doing some of the
10 presentations.
11 I'm Elizabeth Adams. I'm with EPA and a
12 section chief for Southern California section
13 Superfund. We have four project managers, but the
14 two that will be presenting tonight are Eugenia Chow,
15 EPA, and Loren Henning.
16 Catherine McCracken is here. She's from
17 our Community Involvement office, and Randy Wittorp
18 who's back here. He's with media, and it doesn't
19 look like there's any media here. And then we have
20 Brett Moffatt. Brett is from our Office of Regional
21 Counsel. Jon Bishop is from the Regional Water
22 Quality Control Board, And Jacalyn Spiszman is from
23 the Department of Toxic Substances Control. And then
24 Doug Frazer and Bella Dizon, they're with EPA.
25 They're project managers on other parts of the
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1 San Gabriel Valley, and they're here tonight as
2 well.
3 I just wanted to say we welcome you and
4 thank you for coming, and I'm going to turn it over
5 to Catherine.
6 MS. MC CRACKEN: As Elizabeth said,
7 tonight's meeting is part of the EPA's effort to keep
8 the community informed about what is going on with
9 the San Gabriel Valley Superfund Site Puente Valley
10 Operable Unit and to hear what you have to say about
11 the Proposed Plan for that operable unit.
12 This evening you'll have the opportunity
13 to share the information you have with EPA
14 representatives and have your questions answered, and
15 you'll have an opportunity to impact the final
16 selection of an alternative for this site. We'll
17 explain what that means if you're not sure about
18 sharing the comments during the formal comment period
19 a little bit later in the evening.
20 Just before we get started, I want to do
21 a little housekeeping things. First of all, the rest
22 rooms are through that back room, there are pay
23 telephones outside, and the school district has a
24 policy of no smoking on school property. So I just
25 wanted to let everybody know that now so that you
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1 honor that rule so that we can be invited back. And
2 if you need a telephone number here, I have the
3 number of the phone at the back. Let me know, and I
4 can give that to you if you need to let somebody know
5 where you are.
6 We have an information table set up at
7 the back, and there's copies of the Proposed Plan.
8 And I wanted to ask that everyone please be sure to
9 sign in tonight. We have sign-in forms at the back.
10 This helps us keep an accurate mailing- list, and if
11 you are not already on the mailing list, we'll
12 automatically add you. While we're talking about
13 mailing lists, I just wanted to take time to
14 apologize to those of you who are on our mailing list
15 who received this facts sheet just within the last
16 couple of days. We know that's been a problem. So
17 for this reason we wanted to start things off by
18 letting you know we're going to be extending the
19 comment period until March 16th. I know some people
20 were concerned about getting that late, so we're
21 going to be extending that.
22 The agenda for tonight is as follows:
23 Eugenia Chow will provide a brief overview of the
24 Superfund process for the Puente Operable Unit. Then
25 Loren Henning will give a short presentation on the
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1 Proposed Plan; and because of the number of people
2 here tonight, what we wanted to do for questions and
3 answers, there's a question form that I think
4 everybody picked up. If during the presentation you
5 have a question, if you could just jot it down.
6 Because of the size of the crowd what we're going to
7 do is collect those before a short break, and we can
8 go through them and take additional questions. That
9 will help us move more efficiently.
10 There are two other items that you might
11 want to refer to during the presentations. One is a
12 copy of the Proposed Plan fax sheet. We have a list
13 of terms and definitions which you may hear during
14 the presentations and discussions on the back table
15 which may be helpful.
16 After the questions and answers we will
17 be taking formal comments for the record. As you can
18 see, we have a court reporter here tonight. This is
19 Francine. She's going to be providing us with a
20 transcript of the meeting. Some people had asked me
21 what will happen to that transcript, and we will put
22 copies of that with the information already at the
23 information repositories for the site. Those are
24 listed on page 9 of the fax sheet, the local
25 libraries here and the Superfund Center in
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1 San Francisco. If you're not able to stay for the
2 whole meeting tonight there is also a comment form on
3 the back table. You can either leave that with us
4 tonight, or you can mail that to the address on the
5 back of the form, and the deadline will be the end of
6 the extended comment period which is March 16th.
7 I think we'll go ahead and get started.
8 Again, if you can write down your questions during
9 presentations, we'll be happy to cover them in the
10 questions and answers. Thank for coming again
11 tonight.
12 Eugenia.
13 MS. CHOW: Hi, I'm Eugenia Chow. I'm a
14 project manager in the Superfund Division in the EPA,
15 and today I'd like to go over some of the history at
16 the San Gabriel site. First off, I'd like to start
17 with an overview of the Superfund process, followed
18 by a brief description of some of the background
19 events that happened in the San Gabriel site, and
20 finally, I'd like to talk about the Superfund process
21 as it pertains to Puente Valley.
22 We'll start off with the Superfund
23 process overview. The first step in the Superfund
24 process is really the discovery of the site, and
25 sites are discovered in a variety of ways. They can
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1 be identified by local and state agencies, business,
2 EPA, and community members as well. After a site is
3 identified, EPA collects information and assesses the
4 site. And we then score it to evaluate the danger
5 that is posed to public health and the environment.
6 Now, if a site scores high enough, it
7 will be listed on the National Priorities List, and
8 that is the NPL, as it's commonly referred to. The
9 NPL is a list of sites in the country that are
10 eligible for cleanup under the Superfund program.
11 Next up would be the remedial
12 investigation.. This is generally an investigation
13 which determines the extent and type of contamination
14 at the site. This is followed shortly by the
15 feasibility study which is, we evaluate and screen
16 and identify alternatives; and in addition we analyze
17 technologies and develop cost estimates for the
18 different alternatives. Right now we're in the
19 public comment period, and this is really the
20 opportunity for the public to provide comments on all
21 of the alternatives as well as EPA's preferred
22 alternative for the site.
23 After the public comment period EPA will
24 be preparing a record of decision. Record of
25 Decision is a document which sets forth the remedy
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1 for the site. Now, together with the Record of
2 Decision, EPA also prepares a responsiveness
3 summary. And that is a summary of EPA's responses to
4 the formal comments that are submitted during the
5 public comment period.
6 Following the Record of Decision, we'll
7 be moving on to the remedial design and remedial
8 action phase of the project, and that is the design
9 and implementation of the remedy.
10 Next, I'd like to go into-a little bit
11 of the background at the San Gabriel Valley Superfund
12 Site. Here we have a large map of the
13 San Gabriel Valley, and these are the active operable
14 units at San Gabriel. Basically, operable units in
15 this case are geographical areas, and they are
16 usually discrete areas, and we will be addressing
17 them individually as part of a larger remedy. You
18 can see here we have Baldwin Park, El Monte,
19 South El Monte, Whittier Narrows down here, and
20 Puente Valley.
21 Now, to go over some of the chronology
22 at the San Gabriel site, contaminated groundwater was
23 first discovered in 1979. When we say contaminated,
24 we are talking about volatile organic compounds.
25 Shortly thereafter, EPA began its process to identify
10
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1 contamination,, and when I talk about regional
2 groundwater contamination, we're discussing
3 contamination that has moved off site and commingled
4 with other plumes to form a larger groundwater
5 plume.
6 The regional board has been looking at
1 individual site investigations and in some cases
8 requiring site specific or facility specific cleanups
9 as in local source cleanups. We are working jointly
10 together to identify sources and potentially
11 responsible parties since the late 1980s.
12 Risk assessment was completed in 1994,
13 and the risk assessment basically evaluated potential
14 health effects from the contaminated groundwater, and
15 the remedial investigation and feasibility study was
16 just recently completed last year in 1997.
17 Some of you may notice that this
18 groundwater map looks a little different. It just
19 has been updated earlier this week with 1997 data
20 that was gathered. You can see here that the
21 concentrations are represented in terms of maximum
22 contaminant limits commonly referred to as MCLs. The
23 outer line here represents concentrations ranging
24 from detection levels to MCLs. The shaded green area
25 represents, I think, MCL to 10 times MCLs. And the
12
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1 sources at the site and, thus, began the search or
2 the identification of potentially responsible
3 parties.
4 Potentially responsible parties can be
5 individuals or facilities which have been identified
6 to contribute contamination to the groundwater. This
7. process began in the early '80s. The site, the
8 San Gabriel site, was placed on the National
9 Priorities List in 1984, and the following year in
10 1985 operable units were identified.
11 Now, as I mentioned before on the
12 previous map, this is also a basinwide map. We can
13 see here this is actually a composite map of the deep
14 and shallow water in San Gabriel. Groundwater
15 generally flows downward from the Baldwin Park,
16 El Monte area up here. This is Whittier Narrows
17 here. All the water generally flows southwest. In
18 Puente Valley it flows in a northwest direction and
19 flows down through the Whittier Narrows.
20 And finally, I'd like to go over the
21 Superfund process at Puente Valley, in particular.
22 First I'd like to start off by explaining the
23 different roles that EPA and the Los Angeles Regional
24 Board play at the site under the Superfund Program.
25 EPA is looking at addressing the regional groundwater
11
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1 following dotted green pattern represents from 10 to
2 20 times MCLs. The orange represents 20 to 100
3 times MCLs. And the red represents 100 to 1,000. We
4 have a few purple dots which represent concentrations
5 exceeding 1,000 times MCLs.
6 Now, generally in Puente Valley the
7 groundwater flows westward, like I had mentioned
8 before. Down at the eastern end of the Valley, the
9 shallow groundwater ranges from 30 to 50 feet deep,
10 and then down at the mouth, further northwest, it
11 will actually extend down to 200 feet. Similarly, we
12 have a plume map that was developed for the
13 intermediate aquifer at Puente Valley here. We're
14 talking about depths at the eastern end from 80 to
15 100 feet deep, and at the mouth it ranges from 200 to
16 350 feet deep.
17 Now, we are in the remedy selection
18 phase right now of the Proposed Plan, which I hope
19 you all received. It was just released earlier this
20 year in January, earlier this month.
21 Public comments. We're currently in the
22 public comment period, and we are looking for
23 feedback from everyone on the alternatives. We have
24 extended the p>eriod through March 16th, and after the
25 public comment period we will be issuing a Record of
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1 Decision. We anticipate that it will be finalized in
2 late spring. However, the actual date will depend on
3 a variety of factors including the number of the
4 comments that we receive. Then we'll be moving into
5 the remedial design, remedial action phase, the
6 design and implementation of the remedy, and finally
7 the operation and maintenance phase.
8 That pretty much wraps up my general
9 description, and Loren Henning will be presenting the
10 alternatives that we've looked at as well as EPA's
11 preferred alternative.
12 MR. HENNING: Hi, I'm Loren Henning, and
13 I'm the project manager in the Superfund Program. I
14 really would like to avoid using that microphone, so
15 let me know if you can hear me. If you can't it's
16 loud enough.
17 I'm going to be talking to you today
18 about EPA's Proposed Plan for the Puente Valley
19 Operable Unit San Gabriel Valley. I just wanted to
20 point out to you, as Catherine said, this is the
21 Proposed Plan, and it covers everything in more
22 detail than I'm going to be presenting in my
23 presentation. I encourage you to take it home. It's
24 good reading.
25 I'd just like to go over the basic steps
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1 that lead to EPA's choice of preferred alternative.
2 First, we develop remedial action objectives, and
3 these are simply the goals that we wish to achieve in
4 implementing an action at the site. With that in
5 mind we develop a set of alternatives. Those are
6 simply ways in which we can achieve the remedial
7 action objectives.
6 Generally, there's a technical component
9 or some kind of action that is used to help us reach
10 our Remedial Action Objectives for Puente Valley. We
11 developed four alternatives, and I'll be going over
12 those in a little bit more detail in a few minutes.
13 After we developed the alternatives for
14 this site, we evaluate them against EPA's nine
15 criteria, and these are standards that we use to make
16 sure the alternatives that we are going to be
17 evaluating will meet our remedial action objectives.
18 Once that's done against the nine
19 criteria, we choose one of the alternatives as EPA's
20 preferred alternative, and that alternative is one
21 that meets our remedial action objectives. If it
22 satisfactorily completes the evaluation of the nine
23 criteria, we then do is where we are now. We then
24 present that, we wrap all that up and present it to
25 you in what's called a "Proposed Plan" so that we can
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1 take comments. We have a public meeting so that we
2 can present the Proposed Plan to the public, to the
3 community, and answer questions and also take
4 comments. And after that's done, we hopefully,
5 depending on how many comments we get, what your
6 comments are, we may select our preferred alternative
7 as the selected alternative, or we may choose another
8 depending on what the comments are that we receive.
9 The Remedial Action Objectives that were
10 developed for the Puente Valley Operable Unit are to
11 prevent exposure of the public to contaminated
12 groundwater and surface water; inhibit contaminant
13 migration from more highly contaminated portions of
14 the aquifer to less contaminated areas or depths of
15 the aquifer; to reduce the impact of continued
16 contaminant migration on downgradient water supply
17 wells; to protect future uses of less contaminated
18 and uncontaminated areas; and those are outlined in
19 the Proposed Plan.
20 The first alternative that's developed
21 for Puente Valley is the No Action Alternative. EPA
22 is required to evaluate a No Action Alternative
23 basically to provide a base for comparing all the
24 other alternatives. It answers the question: What
25 would happen if we didn't take an action? So
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1 therefore, there are no actions associated with this
2 alternative/ and there are no costs.
3 The second alternative is Groundwater
4 Monitoring. This alternative relies on natural
5 attenuation or natural processes that are occurring
6 beneath the surface to contain and address the
7 groundwater contamination. In order to make sure
8 that the natural processes are occurring and, in
9 fact, containing the contamination, we would be using
10 groundwater monitoring to test the groundwater on a
11 regular basis to make sure that that it is, in fact,
12 happening, and our remedial action objectives are
13 being met. The present cost associated with this
14 alternative is approximately $7.88 million.
15 The third alternative is EPA's Preferred
16 Alternative, and it is groundwater control at the
17 mouth of Puente Valley. The essential components of
18 this alternative are extraction, containment, and
19 treatment of contaminated groundwater in both the
20 shallow and intermediate zones at the mouth of the
21 Puente Valley. Like Alternative 2, in order to make
22 sure that our remedial action objectives are being
23 met, we would be implementing groundwater monitoring
24 to test on a regular basis. The cost of this
25 alternative is $27.8 million. This alternative
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1 incorporates what we call a "performance-based
2 approach," and basically there are specific criteria
3 that the alternative must meet in order to achieve
4 our remedial action objectives. The purpose of using
5 this approach is that it allows flexibility in how
6 you can meet the performance criteria.
7 For Alternative 3, EPA has drafted
8 performance criteria for both the shallow and
9 intermediate zones. The performance criteria for the
10 shallow zone is to apply measures necessary to
11 prevent further migration of groundwater in the
12 shallow zone with VOC contamination above MCLs or
13 possibly a multiple of MCLs from migrating beyond its
14 current lateral and vertical extent. Migration shall
15 not occur beyond a specific buffer zone.
16 There are options for meeting that
17 performance criteria. We could either install a new
18 extraction and treatment system, or use groundwater
19 monitoring to determine whether or not natural
20 attenuation is occurring and meeting our remedial
21 action objectives.
22 Likewise, for the intermediate zone
23 there's performance criteria. It is to provide
24 sufficient hydraulic control, through groundwater
25 extraction, to capture groundwater contaminated with
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1 VOCs above MCLs in the intermediate zone and prevent
2 it from migrating into or beyond the B7 wellfield
3 area depending on the location of extraction.
4 And there's flexibility in meeting this
5 performance criteria as well. We could install a new
6 extraction treatment system or work on an agreement
7 with the water purveyors so that the existing
8 wellfield could be used.
9 The fourth and final alternative
10 evaluated for Puente Valley is groundwater control at
11 the mouth of the Valley and in the mid-Valley area.
12 This alternative has the same components as
13 Alternative 3, that is extraction, containment, and
14 treatment of contaminated groundwater in the shallow
15 and intermediate zones at the mouth of the Valley,
16 but it adds an extra measure of containment and
17 extraction and treatment rather from the intermediate
18 zone at the mid-Valley area.
19 As in Alternatives 2 and 3, groundwater
20 monitoring would be implemented to make sure our
21 objectives are being met, and we also have drafted
22 performance criteria for the intermediate zone at
23 mid-Valley. The cost of this alternative is roughly
24 $27.8 million, and the performance criteria is to
25 protect water quality in the intermediate zone and
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1 deep zones from becoming more contaminated.
2 Those four alternatives were evaluated
3 against the criteria. The nine criteria are divided
4 into three categories. There's threshold criteria,
5 primary balancing criteria, and modifying criteria.
6 There are two threshold criteria, and
7 these are criteria that any alternative must meet in
8 order to be selected as a preferred criteria.
9 Therefore, any alternative that we choose must
10 protect human health and the environment, and it must
11 comply with state and federal requirements.
12 We then use the primary balancing
13 criteria to evaluate the alternatives and determine a
14 best balance of trade-offs among these criteria.
15 There are five. There are long-term effectiveness
16 and permanence criteria, which is how well the
17 remedial action will achieve our objective over
18 time. Reduction of toxicity, mobility, or volume
19 through treatment: Will the remedy reduce
20 contaminant volume and contaminant concentrations and
21 contaminant toxicity? Short-term effectiveness, that
22 is in the construction and implementing of the
23 alternative, will there be any adverse health effects
24 to the environment. Implementability, that's: How
25 easy is it to construct and implement this
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1 alternative? Are there materials readily available?
2 And finally, Cost, which I think is pretty obvious.
3 The last two criteria are the modifying
4 criteria, but they are not the least important of the
5 criteria. It is important to EPA that the state
6 accept and support our alternative, and it certainly
7 is important that the community accept and support
8 EPA's alternative.
9 So these criteria are used at the end of
10 the process to sort of provide a balance or perhaps
11 modify EPA's decision of the preferred and finally
12 selected alternative. In the Proposed Plan -- and I
13 think it's page 6 there's a copy of this table,
14 and this is just basically a summary of the
15 evaluation of the alternatives with the nine
16 criteria. The blue lines divide the criteria, and
17 the top two are the threshold criteria, the middle
18 lines are the balancing criteria, and the last two
19 are the modifying criteria. A solid circle means
20 that the criteria is fully met, and a circle with a
21 line through it means that that criterion is not met
22 at all.
23 For Alternative 1, which is the
24 No Action Alternative, again, that's the alternative
25 where we look to see what would happen if nothing was
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1 done to address the contamination. As you can see,
2 the threshold criteria are not met, so with this
3 alternative/ protection of the human health and the
4 environment and compliance with state and federal
5 requirements are not met, and therefore, this
6 alternative really need not be evaluated any
7 further. And as you can see, it also doesn't meet
8 the remaining criteria.
9 Alternative 2 as well does not meet the
10 threshold criteria. However, it is implementable and
11 doesn't have any adverse health effects during
12 construction or initial implementation of it,
13 Alternative 3 and 4 3 being groundwater control at
14 the mouth of the Valley, and 4 being groundwater
15 control at the mouth and mid-Valley -- both meet the
16 threshold requirements of protecting human health and
17 the environment and complying with state and federal
18 requirements. Both alternatives as well will be
19 effective over the long term. However, Alternative
20 4, because of the additional extraction at
21 mid-Valley, provides an additional margin of
22 long-term effectiveness. The same is true in the
23 reduction of toxicity and mobility or volume by
24 treatment. Both alternatives will reduce contaminant
25 mass in the groundwater; however, because of the
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1 additional extraction and containment at the
2 mid-Valley location, there's potentially an
3 additional measure of reduction of contaminant mass.
4 EJoth Alternatives 3 and 4, the
5 construction of those alternatives would be the same,
6 the duration of that would be the same. So there's
7 virtually not very much difference between the two in
8 terms of short-term effectiveness. There wouldn't be
9 any adverse health effects. And for
10 implementability, both alternatives are
11 implementable, but they are somewhat more involved
12 because of the requirement of constructing a
13 treatment system.
14 There's some probable additional
15 difficulties, perhaps, in obtaining the property for
16 locating the extraction and the treatment system.
17 And so compared to Alternative 2, for example, it is
18 slightly more difficult to implement, and therefore,
19 we said that it partially meets this criterion. And
20 that's just sort of a relative evaluation between the
21 other two alternatives.
22 . As you can see, Alternative 3 meets all
23 of the criteria at a lesser cost. In the modifying
24 criterion, the state, the Department of Toxic
25 Substances, and the L.A. Water Quality Control Board
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1 both concur and support EPA's preferred alternative,
2 which is Alternative 3, and our purpose tonight and
3 during the public comment period is to get feedback
4 from the community, from the public on our preferred
5 alternative.
6 So based on our evaluation of the four
7 alternatives with the nine criteria, EPA's preferred
8 alternative is Alternative 3, that is groundwater
9 control at the mouth of the Valley in the shallow and
10 intermediate zones. It complies with state and
11 federal requirements. It provides a satisfactory
12 evaluation of the remaining criterion at a lower
13 cost, and it also is supported by the state
14 agencies.
15 So our purpose, as I said, tonight is to
16 get more feedback from the community, and with that I
17 think we can start to take questions after break.
18 MS. MC CRACKEN: I think we will take a
19 ten-minute break. And if people do have questions on
20 the question forms, why don't you bring them up to
21 me? And we'll meet back in about ten minutes, and
22 we'll go through the question forms, and we'll also
23 take other questions as they come up.
24 (A brief recess was taken.)
25 MS. ADAMS: I'm going to start with a
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1 question that I picked put of the hat. It's: "How
2 does the EPA plan to comply with California
3 Department of Health Services Memo 97-05 regarding
4 the use of 'highly impaired, ' unquote, water sources
5 for potable water usage?"
6 Just to give some people some
7 background, the memo was written in 1988, but it
8 seems like it's come to light more recently in the
9 wake of things happening in the San Fernando Valley,
10 and luckily, I was in a meeting last week, so I know
11 how to answer this question a little bit.
12 We met with Dr. David Speth of the
13 Department of Health Services. What he had said is
14 that he felt that drawing water from contaminated
15 areas and using it for potable use was not in
16 conflict with the general intent of that memo. I
17 think another part of this concern is that there are
18 situations right now in which PRP company groups are
19 operating treatment systems, and then the water is
20 bought by cities or other water purveyors and
21 distributed.
22 So there's a second issue here in which
23 the Department of Health Services really wants that
24 company to take out a permit so that they can have
25 direct inspection ability and have some control on
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1 the treatment system. So that's kind of a different
2 issue, but in the meeting with DHS they felt that it
3 was we met with the Water Master as well they
4 felt that it wasn't out of line and may actually
5 write a memo to that extent for areas such as
6 San Gabriel and San Fernando.
7 MR. HENNING: The first question that I
8 have is: "What are the health risks or symptoms to
9 exposure to dense non-aqueous phase liquids/ like PCE
10 and TCE?"
11 Just to sort of help define the term and
12 to remind you that it is on the glossary list that's
13 at the back of the table, dense phase liquids simply
14 are contaminants or compounds, like TCE and PCE, that
15 are heavier than water so they tend to sink through
16 water. And one of the problems with having DNAPLs,
17 they're called, is that; one, they can be very
18 difficult to remove from groundwater, and because of
19 their tendency to sink and stay in the groundwater,
20 they can act as a continuing source of groundwater
21 contamination.
22 PCE and TCE, which can be considered
23 DNAPLs, in significant concentrations are considered
24 carcinogens -- and I don't remember off the top of my
25 head what class they are. That's based on tests that
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1 are done on laboratory rats and laboratory animals
2 and extrapolated to predict the effects that they
3 will have on humans. They can also cause respiratory
4 impact, respiratory problems/ leukemia, which is
5 another form of cancer, and you can get rashes.
6 There are those kinds of problems associated with
7 exposure to PCE and TCE.
8 The next question is: "Was an
9 alternative of blending water for drinking, like the
10 San Fernando Valley approach considered, and if so,
11 why was it discarded?"
12 That approached was considered early
13 during the conceptual phase of determining the
14 potential alternatives for Puente Valley. However,
15 it was found that for treating relatively low volumes
16 of VOCs, air stripping was the most cost effective
17 and the most effective at protecting human health in
18 the environment.
19 MS. CHOW: Okay. First question that I
20 have here is: "What is the effect on communities,
21 residences, roadways, businesses in proximity to
22 sites of aquifers during course of Superfund
23 activity?"
24 Let's see if we can turn the overhead
25 projector on here. I'll go ahead and show you the
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1 areas that we have looked at in the feasibility
2 study, and I want to stress that these are just
3 preliminary areas that we have developed in the
4 feasibility study for the treatment options. What we
5 were looking at basically is a line of wells around
6 in this area near the I can't remember it's
7 somewhere near here, and that would really be the
8 area where we were looking at for containing the
9 groundwater at the mouth of the Valley.
10 During the course of construction, if a
11 new system is constructed, there would be the usual
12 noises associated with construction such as
13 trenching, perhaps, for pipes, and the construction
14 of a treatment plant. I want to stress, though, that
15 this may or may not occur depending on the approach
16 that is taken. You know, either the existing system
17 may be used if an agreement can be worked out with
18 the water purveyors, or a new system may be
19 constructed.
20 And the second part of this question is:
21 "How long is the program estimated to take before
22 completion?"
23 Now, I want to go through kind of the
24 steps that we'll have to go through before the
25 project is actually designed and implemented. Right
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1 now we are at the public comment phase. After the
2 public comment phase, we move into preparing a Record
3 of Decision. And after the Record of Decision is
4 finalized, we would go on to look at going into
5 negotiations with the potentially responsible parties
6 to actually perform the work.
7 Following successful negotiations, we
8 would be looking at the design and then the actual
9 implementation, and altogether this could we don't
10 have an exact time frame this could take anywhere
11 from three to five years, just as a general time
12 frame.
13 Second question I have here is: "For
14 Alternatives 3 and 4, how many miles of water
15 collector pipelines need to be built?"
16 In our feasibility study we did develop
17 some estimates for costing purposes of the lengths of
18 pipeline. For Alternative 3, it is approximately one
19 and a quarter miles, and for Alternative 4, we're
20 looking at approximately two and a quarter miles. I
21 do want to stress that these are preliminary
22 estimates that were developed for costs purposes in
23 the feasibility study. The actual lengths and
24 locations would be determined during the remedial
25 design phase.
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1 MR. MOFFATT: I have two related
2 questions here. The first one goes like this:
3 "Currently local water suppliers in this area are
4 pumping wells, such as the B7 wellfield, and treating
5 the water for VOC contamination that is indicated in
6 Figure 3 in the January 1998 handout, then they are
7 selling the water to their customers. The expenses
8 of the VOC treatment has been part of the cost the
9 customers have to pay as ratepayers. Which of the
10 alternatives includes provisions for the responsible
11 parties to pay for the removal of VOCs at existing
12 drinking water wells?"
13 The way the alternatives are laid out
14 right now, they do not specifically address payment
15 or reimbursement to the purveyors, the water
16 purveyors of the cost associated with the ongoing
17 treatment of contamination at those water supply
18 wells. However, our preferred remedy, Alternative 3,
19 through its performance-based approach, provide the
20 flexibility that allows the PRPs to either develop a
21 new system that will extract the groundwater and
22 treat it for VOC contamination thereby eliminating
23 the need for well treatment at the existing
24 wellfield. Alternatively the preferred alternative
25 provides that the PRPs would work with a purveyor in
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1 the B7 wellfield to come up with an arrangement
2 whereby the existing well treatment is incorporated
3 into the remedy.
4 The specific terms of the agreement at
5 this point in time would not be defined and would be
6 generally left up to the PRPs and water purveyors.
7 The second question is: "Do PRPs pay
8 the full cost of the cleanup? Is a portion of the
9 cost covered by EPA or by water rates?"
10 It is generally the EPA's position at
11 most sites, and at this site, that PRPs are
12 responsible for paying for all the costs of
13 remediation. That is our position here. EPA is not
14 ultimately going to cover a portion of the cleanup
15 costs. EPA does incur costs in the process of
16 initiating the cleanup, the remedial investigation
17 feasibility study, and in overseeing the RI/FS, the
18 Remedial Investigation Feasibility activities, and
19 the remedial design studies, but EPA recovers those
20 costs from the PRPs.
21 Therefore, when our selected remedy is
22 implemented, the costs of cleanup will not be
23 directed towards ratepayers.
24 MR. BISHOP: The question is: "The
25 Proposed Plan states that EPA strongly supports the
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1 use of a treatment waiver to reduce costs associated
2 with Alternative 3. Could you clarify this statement
3 by addressing these questions: Question 1, Does the
4 treatment waiver have to be approved under Superfund
5 by EPA?"
6 And before I go and answer, Question 2
7 was: ."Does EPA's strong support mean that EPA is
8 likely to approve such a waiver?"
9 Let me kind of go into the process as we
10 see it right now, and then we'll try arid answer those
11 two questions.
12 Right now, this month or early month of
13 February, management from EPA and the regional board
14 will be meeting to try to come up with a strategy for
15 setting up a policy on all of the discharges from
16 these operable units around the basin. That policy
17 will be put together and then taken to our board for
18 approval as a general policy, and then each of the
19 operable units would then be taken as specific cases
20 that policy and apply to it.
21 In terms of the specific questions, my
22 understanding and EPA is here so they'll jump in,
23 I hope is that the EPA would not be the agency to
24 approve or disapprove a waiver under the it's the
25 regional board who has the delegation of the NPDES,
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1 which is the National Pollution Discharge Elimination
2 System from EPA, and because of that, they have the
3 authority for permitting of discharges to surface
4 water.
5 The terms of EPA's strong support, as I
6 said, they do not have approval ability, but they are
7 working with us to try to come up with a mechanism.
8 MS. MC CRACKEN: I just want to make
9 sure that before we go on to taking additional
10 questions that those who wrote down questions feel
11 that they were answered, so that we can make sure
12 that we went through that all right.
13 GENE LUCERO: Yes. Jon, that was my
14 question. Let me ask you let me tell you, in
15 San Fernando the regional board issued a waiver for
16 one of the operable units. EPA took the position
17 that the board didn't have the authority to issue
18 that waiver and asked the board to retract that
19 decision. The board did retract its decision when we
20 approached EPA about whether or not it would be
21 approved under Superfund as a waiver.
22 EPA's position was they were in the
23 position to grant such a waiver. While you may issue
24 a waiver, it strikes me that EPA has also approved
25 under Superfund, and the question was really directed
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1 at EPA. Are they going to approve issuance of the
2 waiver?
3 MR. BISHOP: My understanding was that
4 there was a specific clause written into the remedy,
5 select remedy, that said about the discharge; is that
6 correct?
7 MR. LUCERO: Yes.
8 MR. BISHOP: And so it was a different
9 situation they took, because they wrote that directly
10 into it that they felt obliged to uphold that.
11 MS. ADAMS: I think Jon is correct there
12 because there was language in the remedy, but
13 basically, the other thing that Jon and I were
14 talking about are you talking about the NPDES
15 portion?
16 MR. LUCERO: Yes.
17 MS. ADAMS: We would work with our water
18 division. Then as far as, let's say if the regional
19 board wanted support on the fact that they were
20 waiving that portion, NPDES permit.
21 MR. LUCERO: But you need two waivers
22 under Superfund. You need the regional board and the
23 EPA Water Division to agree on a water waiver, and
24 you need Superfund Division to agree on a waiver. So
25 you're going to need at least two.
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1 MS. ADAMS: The Superfund one is there
2 for sure. We're working with the regional board for
3 that now. That's part of the process. If we need
4 to, we will also go then to the water division. So
5 far as the Superfund waiver, we may be talking about
6 something different.
7 MR. LUCERO: You have to have both
8 waivers to do that.
9 MR. BISHOP: I don't mean to insinuate
10 that we have approval to do a waiver at this point,
11 but we are starting on the process.
12 MS. ADAMS: I actually wanted to add one
13 clarification. I think in the discussions with
14 Dr. Speth from DHS, I just wanted to give you a
15 little more information. The intent of that, he was
16 looking at broad California, and in general, this is
17 a good idea not to extract contaminated groundwater
18 and use it as a potable drinking water source.
19 However, you know, understanding that there are
20 differences and different needs in different parts of
21 California surface water, groundwater uses, and
22 that's kind of where the discussion led to the fact
23 that he didn't see it that it would be inconsistent
24 with that memo as a whole. So I just wanted to give
25 that clarification.
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1 MS. MC CRACKEN: Thanks. Other
2 clarifications for the written questions or questions
3 that you have? Anyone.
4 Go ahead, sir?
5 THE AUDIENCE: I have a question. I'm
6 not a rocket scientist, and I don't even know how the
7 mousetrap works, but, how do you plan to
8 decontaminate the water under ground without pumping
9 it and filtering it and putting it back into the
10 ground? If I understand, you're trying to get it at
11 the mouth of the contamination portion of the area.
12 All that groundwater runs where it can be probably
13 not be stopped but pumped out of the ground and
14 filtered before it gets to the mouth, otherwise you
15 have about five miles you said about five miles
16 according to my sheet here and by my judgment
17 here, you have about five miles long by about five
18 mile wide contamination.
19 And that water has to run down, and it
20 follows the lower part of the land, and you cannot
21 stop the water. Since you cannot get under there and
22 say, "We're going to stop it here and go another
23 way." It's like trying to stop water in the ocean,
24 trying to keep the warm current from running away.
25 How do you propose to do that? I don't know.
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1 My other question is: Have you found
2 any I don't know how you pronounce the word --
3 perchlorate in this water here?
4 MR. HENNING: I'll try to answer those
5 two questions and try to use this overhead, and you
6 can tell me, sir, if I'm messing up your question,
1 but I think basically you want to know more
8 specifically how are we actually going to treat the
9 water? How are we going to clean? How are we going
10 to address the groundwater contamination? That's
11 your first question; right? Okay.
12 And your second question is: Is there
13 perchlorate in the Puente Valley Operable Unit?
14 Okay. And I'll just use EPA's preferred alternative,
15 which is Alternative 3, to try to give you an example
16 of what the treatment or what the action in the
17 alternative is that we are proposing.
18 We propose that extraction wells be
19 placed at the mouth of Puente Valley, so roughly in
20 this area here. That would be, the exact location of
21 those wells would be worked out probably -- well,
22 during the remedial design. Those wells would
23 essentially pump water out from the ground and treat
24 it through air stripping, and that's basically where
25 we take water and allow air to flow through .it. What
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1 that does is it takes the contaminants, like PCE and
2 TCE, and they go into the air. They volatilize into
3 the air, and that's how they're removed from the
4 groundwater.
5 THE AUDIENCE: And then the air is
6 contaminated.
7 MR. HENNING: Yes, and then the air is
8 contaminated. Then we would provide for another set
9 of treatment for that contaminated air to remove the
10 contaminants to levels that are acceptable, and then
11 that air would not present a risk to human health.
12 THE AUDIENCE: In a controlled bubble or
13 expand it out into the open? Excuse me for asking
14 this question.
15 MR. HENNING: No. It wouldn't be just
16 sort of out in the open where anything, anyone could
17 get exposed to it. It would be part of a design
18 treatment plant, you know, a facility in an area that
19 is enclosed. And then after that has been treated,
20 the water that has been treated is then pumped out
21 and discharged either to one of the surface water
22 bodies in the nearby area or to perhaps one of the
23 water purveyors.
24 THE AUDIENCE: What about, you have
25 wells that move water in the northern part -- in the
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eastern part of the area there, so that wells would
be pumping contaminated water. This is the eastern
part.
MR. BISHOP: I'll just answer that real
quick: Is that, in the eastern part there aren't any
production wells. The production wells are down in
this area here, and they have treatment on them right
now. And the proposed alternative would either use
that treatment, incorporate that, or add new wells
in. The ideai of the extraction is to have enough
extraction there to act as a barrier so that the
water doesn't continue on. It essentially becomes a
hydraulic barrier, and your question on perchlorate
that, as far as I know, there is no perchlorate found
in this area.
MR. HENNING: Some of the production
wells, those wells in the B7 wellfield area, were
tested for perchlorate, and we did from those
tests there was one result that we did get one result
that indicated there was perchlorate there. It was
well below the state level of 18 parts per billion.
It was 6 parts per billion. We'll be sampling again
this month, but there are no known sources of
perchlorate in the Puente Valley Operable Unit. It's
unlikely that; perchlorate will be an issue at
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1 Puente Valley.
2 THE AUDIENCE: The reason that I ask is
3 because I got a letter from my water supplier, and
4 they say that there is perchlorate in some of these
5 areas. And the reason that perchlorate comes from a
6 source is that with a production of munitions, and
7 also rocket fuel, and munitions are a powder. It
8 wasn't too long ago when that factories that blew up
9 in the Nevada area, you know, whether some of that
10 contamination would fly around. It naturally has to
11 settled down, and also the rockets that are sent up
12 into the space, they are to settle down also.
13 I'm not a rocket scientist. These are
14 questions from a ignorant man to the wise.
15 MS. ADAMS: I can just tell you a
16 little bit about where they've seen the perchlorate.
17 I believe our perchlorate expert isn't here tonight.
18 But I believe the La Puente wells, those wells that
19 service people did have some perchlorate in it; but
20 basically this really long groundwater, what we call
21 a plume, you show the groundwater area of
22 contamination. There's one company up there that did
23 manufacture and use the solid rocket fuel. And so
24 the perchlorate is basically within this area. But
25 as Eugenia said, the groundwater does move down to
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1 the Whittier Narrows.
2 So Department of Health Services has
3 been testing drinking water wells just to find out
4 what the extent of the perchlorate is. In
5 Puente Valley they will be doing some more testing,
6 but we haven't seen it so far except for that one
7 well.
8 THE AUDIENCE: My question is based on,
9 you know, like a patient, you give a patient a heart
10 bypass, and a heart valve, but then you found out
11 that he died four months later; or he died from
12 cancer and maybe the doctor didn't check for the
13 cancer when they gave him the heart transplant or the
14 heart bypass. They were interested in giving the
15 bypass and forgot to test for something else, and the
16 patient died of cancer.
17 MR. BISHOP: So yes, we have been
18 testing for perchlorate in the area to make sure that
19 we don't run into that exact problem.
20 MS. CHOW: Next month we are testing for
21 perchlorate throughout Puente. All the monitoring
22 wells we have here will be tested. The one hit that
23 we mentioned earlier is in this wellfield area right
24 here, and I believe there were some hits down here
25 that were coming down from Baldwin Park. They were
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1 further west.
2 THE AUDIENCE: Thank you.
3 MS. CHOW: Yes.
4 THE AUDIENCE: Since you have that map
5 up, from here it's pretty clear that the Baldwin area
6 is different in its form than Puente Valley. Does
7 the Puente Valley come below outward towards
8 Whittier Narrows? It looks like it sort of pulls.
9 MS. CHOW: Actually, it flows this
10 direction. It flows northwest, and if comes around
11 and goes through the Whittier Narrows. Whereas these
12 other areas, they just generally flow southwest, but
13 they do all go through the Narrows down here.
14 Does that help?
15 THE AUDIENCE: Yeah. So the
16 intermediate zone groundwater doesn't seep any
17 further deeper? It just kind of flows laterally;
18 right?
19 MS. CHOW: No. There is downward
20 migration as well. I should point out that this is a
21 composite map of the deep and shallow. So it
22 combines the information from both plumes. It was
23 really to give you an overview of where the plumes
24 are in the basin.
25 THE AUDIENCE: You didn't mean the
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1 Puente Valley has already reached Whittier Narrows?
2 MS. CHOW: No, as it's presented here.
3 THE AUDIENCE: Has the EPA done any
4 tests along the area south along the Baldwin Park
5 plume and the north area of the Puente Valley plume
6 to determine vrhether there is a barrier between the
7 two areas?
8 MR. HARRIS: We have no evidence of such
9 a barrier. If you mean a barrier separating
10 Baldwin Park from Puente Valley, we don't have any
11 direct evidence of anything like that. There has
12 been some testing.
13 MS. MC CRACKEN: If there are no other
14 questions, before we start the official comments to
15 the record, I just wanted to explain how that wo,rks
16 in case you haven't been to a meeting like this
17 before; and I also wanted to let you know that we're
18 going to be here, there's some information up here on
19 the maps, and I encourage you to talk with any of us
20 after the meeting or ask additional questions
21 one-on-one.
22 Go ahead at the back,
23 THE AUDIENCE: If the work is going to
24 be done through the current purveyors of water, will
25 they be charging their customers or residences some
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1 kind of fee for the interruption in their services?
2 MR. MOFFATT: Just for clarification
3 were you asking if there would be charges associated
4 with the interruption of service? Although the
5 details have not been worked out at this point, we
6 would not anticipate that there would be any
7 interruption of service. We don't anticipate that
8 the water purveyors would have reason to charge their
9 customers for the implementation of this remedy,
10 either the cost of implementing it or any other
11 aspects of the remedy. Does that answer your
12 question?
13 THE AUDIENCE: I just wanted to express
14 for the record our support for EPA's preferred
15 alternative
16 MS. MC CRACKEN: Can you hold on for one
17 minute? We'll get to you. Let me just explain how
18 this works. This is an opportunity for you to voice
19 your opinions and your comments for the official
20 record. It will be taken down by the court reporter.
21 If you would like your name to be recorded as part of
22 the comment, please say your full name and spell your
23 last name. That will help us keep an accurate
24 transcript.
25 Because this part of the meeting is only
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1 to strictly hear your comments and opinions, the EPA
2 representatives that have been answering your
3 questions will not respond to comments. The point of
4 this meeting is to collect those comments, not to
5 reply to them immediately, and then the
6 responsiveness survey that was mentioned before is
7 the document in which EPA will respond to comments.
8 The only exception to that is that if there's some
9 type of inaccurate information, we might go ahead and
10 correct that just so everybody can benefit from being
11 here tonight.
12 Your comments tonight as well as the
13 written comments that are submitted are used to make
14 .the final determination for the remedy selection
15 process. Those who make comments tonight will
16 automatically get the written response to comments
17 which will be prepared by EPA. Also, I will let you
18 know how to get a copy of that document, when they
19 are prepared, just as the meeting transcript tonight
20 will be placed in the document collection at the
21 information repositories for this.site, and those are
22 listed on page 9 of the Proposed Plan facts sheet.
23 Let's go ahead and move on to
24 comments. Just to help me figure out how many people
25 are going to make comments, raise their hands if
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1 they're planning to make a comment, just so I have a
2 sense of time.
3 Let's start at this table right here.
4 MR. GEOCARIS: I'm Jim Geocaris. I'm
5 working with the City of Industry, and we have a
6 short comment. As many of you at the agency know, we
7 have had an interest in this since at least 1994.
8 The City of Industry is pleased that the
9 U.S. EPA Region IX has selected Alternative 3 as the
10 Proposed Plan for the Puente Valley Operable Unit.
11 The alternative fulfills the fundamental purpose of
12 containing the horizontal migration of the existing
13 contaminants out of the Puente Valley into clean
14 groundwater areas in the main San Gabriel Basin, at
15 less cost than the competing pump-and-treat
16 alternative. That was our concern from
17 environmentalist standpoint. That's what this one
18 does.
19 We really need to stop the contamination
20 where it is. As such as being a more efficient
21 alternative, we think it's more likely to gain a
22 consensus support of all interested parties needing
23 to move to plan implementation. If we can get into
24 the ground, that's a lot better, and we think
25 Alternative 3 is the best for that.
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1 The City would like some things done to
2 clarify both physical features of the remedy and also
3 other aspects from the Superfund process that are
4 related, although not directly, with the physical
5 remedy. We will be submitting comments in detail.
6 Specifically, the PRPs who we'll be looking at to pay
7 this, the city and water companies that might
8 participate in other ways, and it's from that
9 perspective that we'll be submitting some official
10 comments and asking you some questions.
11 So again, we're glad you selected this
12 alternative. We think it will do the job. We're
13 working with you on refining things and getting more
14 specific. Thank you.
15 MS. MC CRACKEN: Why don't we take the
16 comment you started to make? If you could also spell
17 your last name.
18 MR. NICHOLSON: My name is
19 Bob Nicholson. I'm with San Gabriel Valley Water
20 Company, and again, wanted to express our support for
21 the EPA preferred Alternative 3. There's been some
22 reference made here tonight to the B7 wellfield,
23 which our company is at least part of that, and we
24 wanted to say that we stand ready to enter
25 discussions with EPA and the Puente Valley Steering
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1 Committee on how our wells in the B7 area might fit
2 into the plans in Alternative 3.
3 As has been mentioned, we already have
4 two treatment plants on our wells there. We are
5 cleaning up the water/ and it would seem to make
6 intuitive sense to incorporate that into the plan.
7 And I think the question of the permanence of that
8 San Gabriel Valley Water Company Water Unit as such
9 in the B7 wellfield are committed to the public use.
10 We have to supply water to the water customers in our
11 service areas. So we add an area of permanence
12 there, and again, it's already going on.
13 So I wanted to express our support, our
14 willingness to meet and confer with parties to see
15 how we can be a part of the plans, and that's all.
16 We will probably be submitting written comments also.
17 MS. MC CRACKEN: Thank you. Other
18 comments?
19 Go ahead, and then we'll go to the
20 back.
21 MR. WALTER: Good evening. My name is
22 Bob Walter from TRW, and I'm Chair of the Puente
23 Valley Steering Committee. The Puente Valley
24 Steering Committee is a group of businesses that
25 cover approximately 40 properties located in the
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1 Puente Valley Operable Unit. Our members include
2 various small businesses to very large businesses and
3 everything in between. These are the companies that
4 are actively involved in investigating and cleaning
5 up contaminants in their area. Not all of the
6 parties have been identified so far, and we believe
7 that we're only a portion of the parties that will
8 get involved in this situation.
9 Our group has been involved in this
10 project since 1993. We've been involved in
11 collecting the data that has gone into the RI/FS, and
12 we appreciate the opportunity to provide comments.
13 We'll provide brief, verbal comments tonight. We'll
14 also be providing more detailed, written comments in
15 the future.
16 We thank EPA for extending the comment
17 period for an additional 30 days. A couple of points
18 on a general nature.
19 We agree with EPA that localized,
20 facility-specific actions are an important component
21 of the remedy. We also appreciate the fact that EPA
22 has crafted performance criteria, that the final
23 remedy must achieve, and that those performance
24 criteria will provide a measure of flexibility in
25 this process,. The primary message that we want to
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1 deliver tonight is that our group appreciates EPA's
2 efforts and will continue to work with EPA and the
3 state agencies on this project.
4 And now I think we'd like to turn over
5 the presentation to Dave Chamberlin from
6 Camp Dresser & McKee who is our group consultant, who
7 will provide more detailed comments.
8 MR. CHAMBERLIN: Thank you, Bob.
9 We'd like to discuss three issues
10 regarding a proposed plan this evening-. First, the
11 description of health risks potentially posed in the
12 Puente Valley Operable Unit. Secondly, the
13 facility-specific actions in the
14 Puente Valley Operable Unit. And thirdly, the
15 proposed Alternative 3.
16 The first point is that we are very
1"7 convinced that EPA has greatly overstated the risk
18 posed by VOCs in the groundwater of the PVOU.
19 As affirmed by EPA in the Proposed Plan,
20 the drinking water in the area is safe. And there is
21 every reason to believe that it will continue to be
22 safe in the future. Yet the Proposed Plan seems to
23 ignore this point by claiming that based on
24 calculations by EPA, that an unacceptable risk for
25 exposure to contaminated groundwater is, quote,
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1 reasonably expected to occur, unquote. This risk
2 calculation is based on the highly unlikely scenario
3 that an illegal domestic water supply well would be
4 installed in the heart of a privately owned
5 industrial facility, into the highest known
6 contamination, and that the contaminated water would
7 be illegally distributed to the public for 30 years.
8 In fact, access to and delivery of the
9 groundwater, .is EPA knows, is carefully controlled.
10 Existing governmental controls, including but not
11 limited to Water Master Rule 28, California Title 22,
12 and California Department of Water Resources Division
13 regulations regarding water well installation, all
14 fully and unequivocally protect the public from
15 groundwater contamination in the PVOU.
16 EPA also states that the potential
17 presence of DNAPLs as Loren described it's an
18 acronym for dense non-aqueous phase liquids, meaning
19 pure solvent product is the principal threat in
20 the PVOU. However, there is no direct evidence that
21 such pure solvent product actually exists in the
22 groundwater today, nor is there any evidence that its
23 hypothetical existence would indeed pose a direct
24 threat or risk to the public.
25 EPA notes in the Proposed Plan that all
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1 of the PVOU aquifers are municipal water sources.
2 However, the shallow aquifer in the Puente Valley is
3 not a drinking water source due to the total
4 dissolved solids and nitrates which were not caused
5 by the industrial facilities. Because of the TDSs
6 and nitrate concentration, the shallow aquifer is not
7 used presently as a drinking water source.
8 The generalized site description in the
9 Proposed Plan suggested that contaminated groundwater
10 from the PVOU is flowing through Whittier Narrows and
11 into the Central Basin. As EPA has acknowledged, no
12 migration of contaminants from the PVOU to the
13 Whittier Narrows is occurring, nor do we expect that
14 it is likely to occur in the future.
15 These overstatements of risks, we
16 believe, should be eliminated from the Proposed Plan
17 because they will lead to the overdesign of the
18 remedy. There is no risk of exposure to contaminated
19 groundwater in the PVOU, and thus, the remedies
20 should not be justified on such an unlikely risk.
21 On our second point, the description of
22 the alternatives does not acknowledge the substantial
23 role and benefit that facility-specific remedial
24 agencies have already taken. At a number of the
25 facilities within the PVOU, the PRPs have undertaken
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1 and completed remedial actions, and many others are
2 ongoing. These facility-specific actions have
3 already successfully removed a sufficient amount from
4 shallow groundwater, thereby eliminating the VOCs as
5 threats to the groundwater quality.
6 Localized, site-specific actions have
7 removed more VOCs at a lower cost than the removal
8 EPA estimates will be achieved by proposed
9 Alternative 3. It is clear that facility-specific
10 actions are the most cost-effective means of removing
11 contaminants. And we agree with the agency's view
12 that they should be an integral part of this remedy.
13 With regard to the third point, we
14 believe that Alternative 3, as described in EPA's
15 feasibility study, a centralized, regional
16 pump-and-treat system for the shallow zone is not
17 appropriate. This description should not be carried
18 forward in the Proposed Plan or the Record of
19 Decision. This description does not take into
20 consideration recently collected data and the
21 importance of facility-specific actions. The PVSC
22 undertook an aggressive data collection program in
23 the fall of 1997. This program was designed to
24 provide critical information to support the selection
25 and definition of a remedy. The Proposed Plan does
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1 not acknowledge the availability of these data and
2 their impact on the proposed remedy.
3 For example, the recently collected data
4 show that the shallow groundwater contamination
5 occurs in several smaller sub-regional plumes rather
6 than the larger plume depicted by EPA in the
7 Proposed Plan. This will be unworkable. We believe
8 that the data collected by the PVSC in the fall of
9 1997 support an approach which is focused on
10 facility-specific actions with potential sub-regional
11 actions, rather the centralized, regional approach as
12 outlined in the Proposed Plan for costing purposes.
13 We recognize that the Proposed Plan
14 includes performance criteria to allow greater
15 flexibility in implementing the Alternative 3
16 remedy.
17 As Bob Walter indicates, we appreciate
18 EPA's attempt to maintain this flexibility, and we
19 continue to look forward to working with EPA to
20 further refine this performance criteria. We thank
21 you for the opportunity to present these limited,
22 oral comments this evening, and as stated previously,
23 the PVSC will submit additional comments to the EPA
24 in writing. And we look forward to working with EPA
25 to resolve these issues. Thank you.
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1 MS. MC CRACKEN: Other comments?
2 Yes, sir.
3 MR. ARIGHI: My name is Dan Arighi. I
4 am currently vice president of the water association
5 representing the producers of Central Valley. The
6 producers in the Central Valley support the
7 plan EPA proposed in Alternative 3, and would hope
8 that EPA works with the purveyors in the
9 Puente Valley to remediate and take care of the
10 problem up top here, working with the producers and
11 treatment devices in place. And even if that water
12 is not going to go to the Central, we hope that it
13 doesn't go down into the Central Basin.
14 So we hope that EPA would work with the
15 purveyors in this basin here to implement treatment,
16 and contain contamination up top here before it goes
17 to Central Basin and contaminates the uncontaminated
18 wells that are down in Central Basin.
19 Thank you.
20 MS. MC CRACKEN: Thank you. Other
21 comments?
22 Yes, ma'am.
23 MS. WILLIAMS: Carol Williams,
24 W-i-1-l-i-a-m-s. San Gabriel Basin Watermaster. I
25 just wanted to say that the Waterraaster is on record
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1 supporting Alternative 3, the Proposed Plan. The
2 spread of contamination to our drinking water wells
3 clearly indicates that "no action" or "monitor only"
4 is not sufficient. The Proposed Plan, Alternative 3,
5 is practical, is reasonable, and the performance
6 criteria that you've described allows sufficient
7 flexibility to keep cost minimum and the conditions
8 warranted.
9 MS. MC CRACKEN: Thank you.
10 Other comments?
11 MS. CHAU: Cathy Chau with
12 Suburban Water Systems. I'd like to express our
13 support for Alternative No. 3, and we will look
14 forward, and we will follow up with written
15 comments.
16 MS. MC CRACKEN: Any other comments?
17 Well, thank you very much for your --
18 first of all for your interest tonight. I think
19 we're really pleased with the turnout for your
20 questions and comments. As I said, we'll be here to
21 talk with you. We have the room for another hour or
22 so, and thank you again for attending tonight's
23 meeting.
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(Whereupon, at 9:00 P.M.,
the community meeting was concluded,
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STATE OF CALIFORNIA )
COUNTY OF LOS ANGELES )
I, FRANCINE DI GIORGIO, CSR No. 11404 in
and for the State of California, do hereby certify:
That said proceeding was taken down by
me in shorthand at the time and place therein named,
and thereafter reduced to typewriting under my
direction; and the same is a true, correct, and
complete transcript of said proceedings.
I further certify that I am not
interested in the event of the action.
WITNESS MY HAND this I c^\^ day of
, 1998.
ertified Shorthand Rporter
for the State of California
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