EPA Superfund Record of Decision: San Gabriel Valley (AREA 4) EPA ID: CAD980817985 OU 01 La Puente Ca 09/30/1998


                                    EPA/ROD/R09-98/083
                                    1998
EPA Superfund
     Record of Decision:
     SAN GABRIEL VALLEY (AREA 4)
     EPA ID:  CAD980817985
     OU01
     LA PUENTE, CA
     09/30/1998

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EPA 541-R98-083

                           INTERIM RECORD OF DECISION                       40106

                        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

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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 Alternative 1 — No Action
    8 . 2 Alternative 2 --- Ground-water Monitoring
    8.3 Alternative 3 --- Ground-water Control in the Shallow and Intermediate Zones
        at the Mouth of the Valley
    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
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
    9.7 Cost [[[  9-8
    9 . 8 State Acceptance [[[  9-8

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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/FS—Chemical-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.

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.

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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 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 llllF (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

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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 sguare 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 Surface 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 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
aguifer 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

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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).

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
silty 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.

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

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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 of Alhambra (Case Number 924128). This 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

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Gabriel Basin Watermaster.


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
subseguently 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 (AOQ 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  (CDM, 1993). Intrinsic to the
adopted approach was the assumption that parcel- or source-specific actions will coniinue 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 guality in the shallow zone.

The goals 1 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 guality 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.

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1 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.

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.
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 guestionnaires 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 reguest
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), reguesting 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 reguired 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) reguests 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, 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.
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 ineach
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 II 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
tributary 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 sguare 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
accomodates 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 RWQCB, 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.
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 reguirements (ARARs).

7.2 Exposure Assessment

Exposure assessment is the determination or estimation of the magnitude, freguency, duration,

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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

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:

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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).

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 guantitatively 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).

       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 noncarcinogenic and carcinogenic risks associated with them.

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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 -6 ). An
excess lifetime cancer risk of 1 x 10 -6 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 -6 as an acceptable incremental cancer risk above background, and an
excess lifetime cancer risk of one in ten thousand (1 x 10 -4) as the point at which action is
generally warranted at a site (EPA, 1991c), thus creating EPAs generally acceptable risk range
of 1 x 10 -4 to 1 x 10 -6.

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 guotient (HQ). An HQ less than one indicates that
noncarcinogernic effects from exposure to that chemical are unlikely. Hgs 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 -6 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 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 -4 in
well group 5. For the average inhalation scenario, the estimated excess lifetime cancer risk
ranges from 7 x 10 -7 in well group 1 to 2 x 10 -4 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 -5 in well group 1 to 3
x 10 -3 in well group 5. RME inhalation risks ranged from 2 x 10 -6 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

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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 and 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
guantitatively evaluate potential risk to current workers and futures workers and residents as a
result of exposure to contaminants in ground water through the transportof 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 guotient 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 aguatic 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 considerably higher than the detected
concentrations. Therefore, no adverse impact to aguatic 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.
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
aguifer 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) (1) (iii) (F)) .

The RAOs for the PVOU do not include numeric, chemical-specific objectives in the aguifer 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 the aguifer, 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

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• 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
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 dining the remedial design investigation.

Treatment

Extracted ground water will be treated by either air stripping with offgas treatment or
liguid-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 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.

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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 acition 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 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

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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.
9 Summary of Comparative Analysis of Alternative
The four remedial alternatives described in Section 8 are compared to the Superfund 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 adeguate 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 reguirement of Section 121(d) of CERCLA that
remedial actions at least attain legally applicable or relevant and appropriate
federal and state reguirements, 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 egually protective alternatives.

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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 reguires that all alternatives be assessed to determine whether they can adeguately
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 aguifer. 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 reguirement 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.

9.2 Compliance with ARARs

This evaluation criterion is also a threshold reguirement and is used to determine if each
alternative would attain federal and state ARARs, or whether there is adeguate 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 aguifer.

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Alternatives 1 and 2 are assigned low rankings because they do not meet this threshold
reguirement 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 adeguacy 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 aguifer.

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 modeling. 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 modeling 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. Modeling results indicate that only 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 guantity of treatment residuals that will remain following treatment

              9.4.1 Reduction of Toxicity, Mobility,  or Volume Through Treatment:  Evaluation of
              Alternatives

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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
liguid-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.

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 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

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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 unmitigable 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 unmitigable 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 reguired 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 reguired for construction and operation of the remedy

•      Availability of Services and Materials

         - Availability of necessary eguipment,  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.

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

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agreements for monitoring well installation. Implementation of Alternatives 3 and 4 would
reguire acguisition of property and/or easements for the construction of extraction wells,
treatment facilities, and conveyance facilities.

In addition, implementing Alternatives 3 or 4 would reguire 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 and Materials. Implementation of Alternatives 3 and 4 would reguire
fabrication of treatment plant eguipment. Reguired services and materials are believed to be
available, including gualified 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 reguired in Alternative 4 are more likely to lead to
schedule delays.

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,
eguipment, 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

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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.

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 guestions at the public meeting held in January 1998 to discuss EPA's plans. EPA
responded directly to the oral guestions and comments at the public meeting. The entire
transcript for the public meeting is included in the Responsiveness Summary in Part II 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.
10 Selected Remedy


After considering CERCLA's statutory reguirements, 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

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10 times the ARARs listed in Table 1 from migrating beyond its current lateral and vertical
extent as described in the RI/FS for 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 liguid-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 1 from 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.

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
              liguid-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 adeguate 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 guarterly 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.

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Imminent exceedence of the performance criteria at compliance wells indicates that ground-water
contamination is migrating, and hydraulic containment is reguired. Any actual or imminent
exceedence of the performance criteria at the compliance wells will reguire 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.

The "Shallow" and "Intermediate" Zones

The shallow zone generally encompasses the upper 100 feet of the saturated aguifer, 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 aguifer 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 (CDM, 1997).

The "shallow" and "intermediate" zones are terms intended to describe general horizons within
the aguifer(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 that
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 aguifer materials in the shallow zone
are variable. Remediation of migrating contamination in the shallow zone reguires careful
analysis of this variability, and an adeguate 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 adeguate 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
adeguately located to ensure that contamination above MCLs does not migrate away from the B7
Well Field Area.

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

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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 adeguate 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 reguirement prevents, for example, the installation of new 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.
11 Applicable or Relevant and Appropriate Requirements (ARARs)
Section 121(d) of CERCLA, 42 U.S.C. ° 9621(d) reguires that remedial actions at CERCLA sites
attain (or justify the waiver of) any federal or state environmental standards, reguirements,
criteria, or limitations that are determined to be legally applicable or relevant and
appropriate. These applicable or relevant and appropriate reguirements are referred to as
"ARARs." Federal ARARs may include reguirements 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
reguirements and that are identified by the state in a timely manner.

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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 reguirements are those cleanup standards,  standards of control,  or other
              substantive reguirements,  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
              reguirements may be applicable.

       •      Relevant and appropriate reguirements are those cleanup standards, standards of
              control,  and other substantive reguirements,  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 reguirements
              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, reguirements,  and
pertain only to onsite activities. Offsite activities must comply with all applicable federal,
state, and local laws, including both substantive and administrative reguirements, 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
              reguiring ARARs may include floodplains,  wetlands,  historic places,  and sensitive
              ecosystems or habitats.

       •      Action-specific ARARs are technology- or activity-based reguirements 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

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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.
00 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 adeguate 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) 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 reguirements
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 plant, 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) reguires 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

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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 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
reguirements 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 guantities 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
reguirements 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 reguirements 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 Antiguities Act, 16 U.S.C. °° 461-467, 40 C.F.R. Part
6.301(a), reguires 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 reguirements of the California H&SC, through local
air guality 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.

SCAQMD Regulation XIII, comprising Rules 1301 through 1313, establishes new source review
reguirements. Rule 1303 reguires that all new sources of air pollution in the district use best
available control technology (BACT) and meet appropriate offset reguirements. Emissions offsets
are reguired for all new sources that emit in excess of one pound per day.

SCAQMD Rule 1401 reguires that best available control technology for toxics (T-BACT) be employed
for new stationary operating eguipment, 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 -5).
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.

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              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 qround
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 arid 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
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 (N03-N + N02-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

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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 Planfor 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) reguires attainment
of background water guality or, if background levels cannot be restored, the best guality 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.

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 aguifer 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 reguirements for the management and disposal of hazardous wastes.
Ln 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 Reguirements

CCR Title 22 establishes reguirements applicable to generators of hazardous waste.
Lmplementation 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 eguipment). Hazardous waste may also be generated as a result of ground-water
treatment to remove VOCs (e.g., spent carbon). These reguirements 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
reguirements (55 Fed. Reg. 8691). Manifest reguirements are ARARs in the event that the remedial
action involve multiple water treatment units at different locations and reguire the movement of
hazardous wastes (e.g., spent carbon) between these locations.

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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.

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.
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

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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 aguifer and will permanently reduce the volume of contamination by
limiting the migration of contaminants and removing contaminant mass.

13. 4 Community Acceptance

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 received during the public comment period, along with
EPA's responses, are presented in Part II 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 adeguate 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.
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.

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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 CH2M
HILL. March 1994.

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.

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                                    Table 1
                     ARARs for Chemicals of Potential Concern
              Compound
1,1-Dichloroethane
1,1-Dichloroethene
1,1,1-Trichloroethane
1,1,2-Trichloro-l,2,2-trifluoroethane
1,1,2-Trichloroethane
1,1,2,2-Tetrachlorethane
1,2-Dichlorobenzene
1,2-Dichloroethane
1,2-Dichloroethene  (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-Ethylhexyl)phthalate
Bromochloromethane
Bromodichloromethane 2
Bromoform 2
Bromomethane
n-Butylbenzene
see-Butylbenzene
tert-Butylbenzene
Carbon Bisulfide
Carbon Tetrachloride
Chlorobenzene
Chloroethane
Chloroform 2
cis-1,2-Dichloroethene
cis-1,3-Dichloropropane
Dibromochloromethane 2
Dibromochloropropane
Di-n-butylphthaiate
Dichlorofluoromethane
Ethylbenzene
Isopropyl alcohol
Isopropyl benzene
Methylene Chloride
Naphthalene
Styrene
 ARAR
(Ig/L)
  5
  6
 200
1,200
  3
  1
 600
 0.5
 6 1
  5
  70

 600
 0.5
  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

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                                    Table 1
                     ARARs for Chemicals of Potential Concern

                                               ARAR
              Compound                         (Ig/L)         Source
Tetrachloroethene                               5        Federal MCL
Total petroleum hydrocarbons
Total petroleum hydrocarbons-volatiles
trans-1,2-Dichloroethene                       10        California MCL
trans-1,3-Dichloropropane
Trichloroethylene                               5        Federal MCL
Trichlorofluoromethane                         150       California MCL
Toluene                                        150       California MCL
Vinyl Chloride                                 0.5       California MCL
m,p-Xylene 3                                    -              -
o-Xylene 3                                      -              -
Xylenes, total                                1,750      California MCL

1 Value for the cis-isomer, value for trans-isomer is 10 Ig/L
2 These chemicals are trihalomethanes (THMs); the MCL listed is for all four THMs:
  chloroform, bromodichloromethane, dibromochloromethane, and bromoform.
3 Value for total xylenes is 10,000 Ig/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 RI  (PVSC monitoring
wells or Suburban Water Systems wells).

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                                                 Table 2
                 Estimated Total Noncancer Hazard Index from Domestic Use of Groundwater
                                        Puente Valley Operable Unit
                                  Average Exposure
Reasonable Maximum
     Exposure
      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
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
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
                                              Trichloroethene
                                              Trichloroethene
                                              2-Propanone
           Major Chemical Contributors
1,1-Dichloroethene, Trichloroethene
Tetrachloroethene, Trichloroethene
1,1-Dichloroethene,
1,1-Dichloroethene,
1,1-Dichloroethene,
1,1-Dichloroethene, Trichloroethene
Tetrachloroethene, Trichloroethene
Methylene Chloride, 2-Propanone, Trichloroethene
Tetrachloroethene Trichloroethene
Tetrachloroethene, Trichloroethene
1,1,-Dichloroethene, Trichloroethene

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                                                 Table 3
                 Estimated Total Excess Lifetime Cancer Risk from Domestic Use of Groundwater
                                        Puente Valley Operable Unit
      Wells
   Average Exposure

Ingestion     Inhalation
   Reasonable Maximum
        Exposure
Ingestion     Inhalation
Major Chemical Contributors
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
5x10 -7
3x10 -6
4x10 -6
4x10 -6
4x10 -5
7x10 -8
2x10 -7
5X10 -7
7x10 -7
8x10 -6
2x10 -6
1x10 -5
2x10 -5
1x10 -5
1x10 -4
3x10 -7
7x10 -7
2x10 -6
2x10 -6
3x10 -5
  2x10 -4
                 1x10 -4
                                  1x10 -3
                                                7x10 -4
1x10 -4
4x10 -4
4x10 -5
6x10 -5
4x10 -6
6x10 -6
2x10 -4
4x10 -6
2x10 -6
2x10 -6
4x10 -4
3x10 -3
2x10 -4
4x10 -4
2x10 -5
3x10 -5
2x10 -3
2x10 -5
2x10 -5
8x10 -6
                             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

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                                Table 4
                   Cost Comparison of Alternatives 1
                               ($l,OOOs)
                                                                           Net Present  Worth
      Alternative          Capital Costs           Annual O&M Costs          (30-years  @ 5%)
           2                  $2,344                   $360                     $7,878
           3                  $8,276                 $1,270                    $27,798
           4                 $11,751                 $1,634                    $36,869
1 Net Present Worth is based on discharge to San Jose Creek with treatment for VOCs  only.

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                      Table 5
                B7 Production Wells
             Puente Valley Operable Unit

Well Identification               Station Identification
152W1
147W1
105W1
134W1
15 OW1
147W3
B7E
B9
B11A
B7B
B7C
B7D
B9B
BUB
01900337
01901596
01901608
01901623
01902519
08000077
08000122
91901437
91901439
91901440
98000068
98000094
98000099
98000108

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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


                                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 guestions and comments were responded to directly at the public meeting. These
comments or guestions 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 receivied 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.

       1. 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 the shallow zone, the group of cooperating potentially responsible parties organized as
the Puente Valley Steering Committee  (PVSO) has collected data over the last several months
(PVSC)  demonstrating that the plume of contaminated groundwater in the shallow zone migrates as
three subplumes near the mouth of the PVOU, where the Proposed Plan recommends placing the
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

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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 reguirements 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 IXs position in favor of a
waiver of the Waste Discharge Reguirements (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 reguirement 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 them by
reference.

In supporting the Regional Board's grant of this waiver, USEPA Region IX should 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 IX should inform the Regional Board that the TDS and nitrate
waiver reguested for the PVOU superfund remedy is consistent with the applicable reguirements 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 ARAR for
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 guality standards, so long as the
discharge does not cause an exceedence of water guality 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 reguirements for nitrate and TDS. The water guality
standards for nitrate and TDS in San Jose Creek, the San Gabriel River and the Puente and Main

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San Gabriel basin groundwaters 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 IX'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 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 guality 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 justifiled 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 groundwater 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 of VOC 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 groundwater, 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 perform a
preliminary streamlined evaluation of the potential risks associated with contaminated ground
water in the PVOU. To assess potential risks, EPA is reguired 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

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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, inat 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 groundwater.

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 superfund remedy operates are not necessary.

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 Whittier 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

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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
surprisinq because the Remedial Investiqation and Feasibility Study contain extensive data
qathered over several years of qround water contamination in the PVOU byVOCs that are not
DNAPLs, but no direct detection of any DNAPL compounds.

While Reqion IX believes that some indirect evidence exists that "suqqests the possible presence
of DNAPLs, " makinq this mere suqqestion into a "principal threat " qreatly exaqqerates the real
evidence of the DNAPL threat to qround 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 qround 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 qround water at the PVOU, the concept of "principal
threat" does not apply, therefore it is not included in this Interim ROD.

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 followinq
is a list of these assessments:

Administrative
In-Lieu
Replacement Water
Make-up Water
Special.

The City and Aqency 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 qround water controls, replacement water charqes 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 existinq water supply wells and instead install their own
system, they probably will treat this qround 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 charqes, as well as some of the other Watermaster Assessments.

In the shallow zone, the preject sponsors probably will discharqe the qround water, which is
hiqh in TDS and nitrates into a lined portion of the San Jose Creek after they treat it for
VOCS. Such a discharqe may or may not be viewed as transport out of the Main San Gabriel Basin,
dependinq in part on the area where this discharqed water reaches unlined water bodies and
recharqes into qround 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 qround water from the Main San Gabriel Basin. Therefore, the Main San Gabriel Basin
Watermaster could impose the Replacement Water charqe. This charqe currently is $246.65 per
acre-foot. It probably will increase qradually over the years, because it is indexed to
Metropolitan Water District charqes, which are projected to rise in the future.

EPA's Response: The comment correctly points out the need to consider replenishment costs if
qround 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 lonq as the
treated water was discharqed/recharqed back into the San Gabriel Basin. The selected remedy
includes discharqe 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
charqed as a result of implementation of the selected remedy, and the Watermaster reiterated
their support for implementinq remedial actions that extract and treat contaminated qroundwater.

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City Comment IIA: USEPA Region IX should 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 IX should 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 IX for 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 IX to make a decision about all
individual properties, with the exception of properties where the responsible business or
landowner has resisted Board reguests 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 guickly 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 B pp. 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 gualify 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
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 reguires 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 reguired 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's past 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's past 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.

The goal of CBWA 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, Horton, 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
of PCE 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 pathway

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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 adeguately
addressed in the RI/FS for 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 guickly.

Response to Comments from the San Gabriel Valley Water Company (SGVWC),  dated March 11, 1998

SGVWC Comments: This letter supplements my statement at the public meeting held Wednesday,
January 28, 1998, at La Puente 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 28 public 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.

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 IX and 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

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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.

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 groundwater, 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 of VOCs from 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

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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
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 VOCs from 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 PVOU is the possibility
that Dense Non-Agueous Phase Liguids ("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 specie 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
aguifers.

EPA Response: This comment refers to overly conservative assumptions and the existence of
institutional controls as a mechanism for preventing human exposure to contaminated groundwater,
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 groundwater. 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 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

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contaminated ground water beneath and/or downgradient of their respective facilities. As
correctly described in the FS report:

        "[t]hese 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, Spectrol 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 Goe/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, Spectrol Electronics, Lansco
Die Casting, Utility Trailer, and Acorn Engineering. The FS report itself indicates that "[the
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 groundwater 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 modeling 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, if DNAPL layers are present beneath any
of these facilities, EPA's proposed groundwater extraction program may remobilize the DNAPLs
into less contaminated areas of the aguifer and/or deep aguifers.

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 adeguately 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 reguire 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 aground
water model for the PVOU which takes into account consideration the effects that site-specific
remedial actions will have in the overall reduction of VOC 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

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evaluated, new cost-effective remedial alternatives could be developed which meet the EPA' s RAOs
for 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 groundwater, 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
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 ID.

Response to Rovall K. Brown Comments, dated March 12, 1998

Rovall 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 rate
payers 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 tecknical [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 0,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 deter 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

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Alternative #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 tecknical [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 dewaterinq 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 Drinkinq Water Well Field.

Also I not the heavy pumpinq of wells South of the 10 Freeway and East of the 605 Freeway has
caused a pumpinq 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 pumpinq hole. As lonq as
this pumpinq depression continues the threat of any Puente Valey polluted qround water qettinq
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 Drinkinq Water wells, and b) the effects of deep pumpinq on
containinq contamination. The lack of mapped contamination in this area may primarily reflect a
lack of data from the shallow zone. The effects of deep pumpinq in the B7 well field are duly
noted in the Feasibility Study. These wells may be considered part of a reqional remedial action
if the appropriate assurances can be made on their continued pumpinq. In the absence of such
assurances, it cannot be assumed that this pumpinq will indefinitely prevent the miqration 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 larqe area,
167 Square Miles, and has been polluted for such a lonq 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 the followinq manner, which has now been put into motion with
our aqinq sewer problem, by assessinq every property within this area. Tryinq to sinqle out any
small qroup 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 unknowinq employees durinq our war years workinq for the safety of our Country, for this
Government and on the Instructions of this qovernment. These contracted small and larqe
Companies employees, while workinq on Government Contracts durinq this war time period
unknowinqly 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 lonq 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 qot to find ways to lead by exercisinq tolerance toward everyone. The Civil
Riqhts Act was passed in 1964 to insure [sic] these riqhts. Respect these riqhts in your
decision.

EPA's Response: EPA does not have the leqal authority to finance CERCLA (Superfund)
response actions by levyinq assessments on all property owners. EPA and the Reqional Board
have undertaken an extensive investiqation of the businesses and other facilities in the San
Gabriel basin (includinq dump sites) that miqht have been sources of VOC contamination in the
qround water. Of those facilities that EPA has identified as sources of contamination, EPA has
not sinqled out any subqroup 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

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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:

1. 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 Reguirements ("ARARs").
6. Puente Valley Operable Unit, Interim RI/FS, Final Remedial Investigation Report and
Appendices (Camp Dresser & McKee Inc., May 30, 1997).
7. PVSC 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
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 reguests 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.

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 aguifers
... in the PVOU are considered to be municipal water sources...." The Proposed Plan should

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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.

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 VOCs are
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 10 -3 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 of Puente 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.

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 guantifiable reasonable risk of exposure currently exists, nor is one expected
in the future. Furthermore, the Plan states that EPA's alternatives are "designed for 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 (5x10 -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

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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 in flow 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 PVSCs 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 of MCLs",  or otherwise affirming the use
              of multiple of MCLs.
       •       Recognizing that the buffer zone may  be defined differently for different areas of
              the mouth of the PVOU,  and should be  based on a number of factors including the
              aguifer characteristics,  use of aguifer, access restrictions,  etc.

EPA's Response:  EPA has permitted the PVSC to provide substantial input throughout the 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 broadplume 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 aguifer,
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 guoted 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

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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 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 of EPA'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 PVSCs use of
contaminant transport modeling. 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 modeling. However,
contaminant transport models are widely accepted tools to be used in concert with all field data
to assist in predicting the future distribution of VOCs. 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/analyzing 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 of EPA'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.

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

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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 eguipped 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 assumed in
evaluating Alternative 2 the illegal delivery of contaminated drinking water to the general
public. The PVSC 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 reguirements on the use of contaminated ground
water do not affect EPA' s determination that Alternative 2 would not adeguately 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 reguired 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

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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.

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 guantified 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 PVSC's
Section 1.2.4 have been deleted. These paragraphs described the poor water guality and
corresponding lack of domestic use of groundwater 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 aguifer 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 for potable uses to regulated public water supply systems. It should also include a
discussion of the containment of groundwater that is occurring as a result of the operation of
the "B7" wellfield by water purveyors, and the water management objectives of Watermaster 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 subseguent 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

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of drinking water. In addition, not all PVOU ground water has high levels of nitrate and total
dissolved solids (TDS) or poor aguifer 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 aguifers. A range of hydraulic
conductivity for the three aguifers 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 aguifers 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 feature that
affects the guantity 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 subseguent 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 "aguifers" 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 gualified.

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.

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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 "shallow groundwater" discussion is based
on data from facility wells that are part of the EPA database but were not a specific component
of PVSCs 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 offsite 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 the
extent of VOC 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.

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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 B11B and B7C. 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. "EPA1 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 technigues since the early 1980s, when guantitation limits for these compounds were
typically 5 Ig/1. 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 and B11B (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 guality results in SWS wells is attributable to the
purging methodology; the text is inconsistent with the language that the PVSC and EPA 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 correlatable with "deep" zones in mid-valley and mouth of the valley. Section
1.4.1.1 appears to show the same high concentrations of VOCs 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 RI data 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 aguifer" in that area.

EPA's Response: EPA agrees that the extent of the deep zone may need to be expanded further,
however for the purposes of this Interim Action, these differences of interpretation of the East
Valley are not significant.

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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

•      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 listed as having
      PCE concentrations of ND to over 444 Ig/1, 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

•      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 Ig/1 is from
       Ajax well B-19, which is  screened from 20 to 40 feet bgs, and the reported highest TCE
       concentration of 1,036 Ig/1 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 conseguence 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.

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

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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 guality 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 PVSCs text, which described existing data and modeling 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 conseguences 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 aguifer 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
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 guality 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 aguifer 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 modeling 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 B11B 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: There two statements should not be read as contradictory. The continued
migration of contaminants into the B7C and B11B 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 gpm for 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 aguifer upgradient of the B7 wellfield." EPA's statement regarding

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contaminated groundwater in the subdrain re-entering the aguifer upgradient of the B7 wellfield
should be gualified (i.e., contaminated groundwater re-entering the aguifer 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 of desorption 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 of desorption 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 guantification 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 modeling 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 PVSCs 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 aguifers, anaerobic
degradation of VOCs is insignificant. However, in the Puente Valley, the aguifers 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 ofthe groundwater plume over the last 11 years, as cited elsewhere in the FS, is
another factor consistent with biodegradation of contaminants. Conseguently, 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 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
cosidered 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 adeguate
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 "hot

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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 guantitative 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
reguirements 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 deleted from this section are "Similar controls are
available to the Puente Basin Watermaster, although they have been unnecessary since no
extracted groundwater from the Puente Basin is used for drinking water" and "Watermaster
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 unigue 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, which, consistent
with the Safe Drinking Water Act, have protected the public from exposure to contaminants in
excess of MCLs.

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 RI to 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 jails to note that the BRA was broader in scope than the RI/FS and
that, accordingly, not all the general conclusions of the BRA are relevant to the FS. The PMEs
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 Ig/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
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 reguired
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 reguired 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, though, 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 bycertain
entities holding water rights.

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:

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No. Remediation Goal
1. "Preventing exposure of the
public to contaminated
groundwater including but not
limited to, attaining MCLs for
VOCs measured at the point of
compliance."

2. "Inhibiting contaminant
migration from more highly
contaminated portions of the
aguifer to less contaminated
areas or depths of the
aguifer."

3. "Reducing the impact of
continued contaminant
migration on down-gradient
water supply wells."

4. "Protecting future uses of less
contaminated and uncontami-
nated areas and depths of the
aguifer."

5. "Initiating efforts designed to
attain MCLs and MCLGs that
are relevant and appropriate
within the PVOU."
Specified
Acceptable
Exposure

MCLs for
VOCs
Identified
Risk
None
None
None
None
None
None
None
None.
None.
Comment
Generalized statement that represents
SDWA policy. "[M]easured at the point
of compliance" is inappropriate for a
remediation goal, which measures con-
centrations at the point of exposure.
This is a description of a remedial activity
rather than a remediation goal.
The water supply wells are not themselves
a point of exposure to unacceptable risk.
This is a policy statement rather than a
remediation goal as defined by the NCP.
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
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 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 ROD's performance criteria.

The NCP does not reguire 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
contaminated 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:

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RAO
Specified
Contami-
nant of
Concern
Specified
Medium of
Concern
Specified
Exposure
Pathway
Specified
Remedia-
tion Goal
                                                                              Comment
"Prevent exposure of the
public to contaminated
groundwater"

"Inhibit contaminant mi-
gration from the more
highly contaminated por-
tions of the aguifer to the
less contaminated areas
or depths"*

"[T]o reduce the impact
of continued contaminant
migration on
downgradient water sup-
ply wells."*

"[T]o protect future uses
of less contaminated and
uncontaminated areas."*
                              None
  None
              Ground-
              water
              None
                                                      None
                          None
RG#1
                                      RG#2
  None
              None
                          None
                                      RG#3
None   None   None   RG#4
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.
            Merely reiterates RG#4
            which is itself a deficient
            RG.
[*These RAOs are grouped in one bullet point in °3.1.2.5]

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EPA itself has noted that "[r]emedial 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, above. 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) (1) (iii). But EPA's general expectation to restore ground
waters to their beneficial uses does not supersede the reguirements 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 guotation of Section 300.430(a) (1) (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
expectations "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 guoted 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 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 PVOU. EPA's RAOs donor
specify accurate exposure pathways.

EPA's Response: See EPA's responses to PVSC Attachment A Comment 39 and City Comment IE1.

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 PVOU for 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

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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 9234.1-01 (USEPA 1988), 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.

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 contamination, are reguired 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 of aguifer
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
PVSCs 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 reguired to develop interim remedial action alternatives that are
consistent with the expected final remedial action (40 C.F.R. ° 300.430(a) (1) (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 modeling 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.

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PVSC Attachment A, Comment 45: EPA states that delaying action will increase the burden of
responding to the contamination on water purveyors. This statement is unsupported by the RI.
This statement is contradicted by data, referenced in Section 1.4.2.1 of PVSC's FS but omitted
here, that show that wellhead treatment costs will not increase in the absence of an EPA-imposed
pump 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 likelihood 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 reguire 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 conseguently increase the cost, difficulty, and time reguired to contain
contamination or restore the aguifer. 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 sorbed phase 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 aguifer, 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 conseguently increase costs,
difficulty, and time reguired 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. °
300.430(1) (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 PVSCs 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 well as potential future processes and activities. PVSC believes that it
is consistent with the Superfund Administrative Reforms to identify existing control mechanisms,
including both natural processes and institutional ones, as part of performing a realistic

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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/FS process. 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
and RCRA reguirements will be observed), yet assumes that SDWA reguirements 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
aguifer restoration, particularly in a fine-grained aguifer. Although EPA states that aguifer
restoration is an ultimate goal, any attempt to restore the Puente Valley aguifers to pristine
conditions would be impractical and fiscally irresponsible. Conseguently, PVSC's discussion
should be restored so the public is not misled into thinking EPA or any agency will pursue
aguifer restoration.

EPA's Response: The deleted text contained a short discussion about the difficulties of aguifer
restoration under circumstances that might be relevant to the PVOU. EPA will consider the
practicality of restoring the aguifer when EPA evaluates final remedial action alternatives.
There is no basis, and no need at this time, to conclude that aguifer 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 of the "No Action"
alternative does not represent realistic background conditions in the absence of CERCLA action.
A realistic description should recognize that established functions 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 reguirements. 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 and SDWA reguirements.

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 PVSC. 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

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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 guality 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 the production wells will continue to pump into the future to provide containment
over the life of the CERCLA remedy, this FS does 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 wellfield pumping 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, Spectrol, 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.

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 of VOC's could occur from one zone to another, due to "downward
gradient". These statements regarding downward gradient are repeated throughout Sections 4 and

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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 aguifer. EPA's statement
appears to be based on overly simplistic analysis that looks only at the hydraulic gradient.
Water guality data, pumping tests, and contaminant transport modeling indicate that the aguitard
below the intermediate aguifer precludes the downward migration of significant quantities of
contamination. These sections of the FS should include this interpretation 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 wellfield 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 [intermediate zone ground water at mouth of the valley] if continued operation
and treatment can be ensured, costs are reasonable, and ongoing monitoring 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 Groundwater
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 Ig/L range.

EPA's Response: The deep zone is an existing source of drinking water. VOCs in the 5-10 ug/L
range may exceed drinking water standards.

PVSC Attachment A, Comment 63: Section 4.1.2 - Objectives of the monitoring network include work
that should actually be part of further data collections (such as delineating the nature and
extent of contamination). This work should be performed prior to selection of a remedy. One of
EPA's justifications for additional monitoring wells apparently is related to the fact that B7
wellfield extraction is not considered as part of Alternative 2. If operation of these wells was
assured, fewer or possibly even no additional monitoring wells might be required

EPA's Response: Extraction from the B7 wellfield is considered as an option in Alternative 2.
EPA supports early performance of data collection activities, however, does not agree that it is
required in order to select a remedy.

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PVSC Attachment A, Comment 64: Section 4.1.2.1 - EPA proposes to install additional mid-valley
monitoring wells in the intermediate and deep aquifers. Water quality data and contaminant
transport analysis indicate that existing monitoring wells in the mid-valley area are adequate
to monitor the intermediate and deep aquifer in that area, particularly since water quality data
and contaminant transport modelling indicate that significant migration of contaminants from the
intermediate aquifer to the deep aquifer is not expected to occur. Even if mid-valley pumping
from the intermediate aquifer is implemented, the existing network of monitoring wells is
expected to adequately monitor up- and downgradient conditions.

EPA's Response: EPA does not agree that existing mid-valley monitoring wells are sufficient.

PVSC Attachment A, Comment 65: In Section 4.1.3, EPA asserts that "there are several water
purveyors in Puente Valley that may be interested in accepting treated water". This statement
appears to be without substantiation.

EPA's Response: At the public meeting for EPA's Proposed Plan several water purveyors stated
their interest in accepting treated water (see transcript of public meeting).

PVSC Attachment A, Comment 66: Also without substantiation is the statement that the RWQCB will
issue a waiver for discharge of water with elevated TDS and nitrates. EPA should 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 modeling. 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 confusing. It
does not consider LARWQCB-led actions, 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 ofthe B7 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
should 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

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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
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 subseguent response actions. No-Action alternatives do not include
institutional 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 B7 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 "l-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 reguirements 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 reguired for... restoration of the aguifer". Aguifer
restoration in a site such as the PVOU is generally considered to be technically 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 reguired to achieve compliance at the tap. An unstated advantage of Alternatives 1 and 2
is avoidance of the expense of a potentially unnecessary treatment alternative.

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
aguifer restoration is infeasible. See EPA's response to PVSC Attachment A Comment 50. EPA

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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 1 is properly characterized, it is apparent that
all four alternatives are egually 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. Alternatives 3 and 4
must re-invent the Watermaster system and the SDWA 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 guality.

PVSC Attachment A, Comment 74: Section 5.1.2 - EPA states that "Alternatives 1 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
redundant measure in view of the wellhead treatment and blending that is occurring at the B7
wellfield. Modeling 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 concentrations are
expected at production wells, this is unsupported. Water guality 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: Modeling is a simplification of actual processes and must be interpreted with
respect to the assumptions made during the modeling 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 RAOs for 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 aguifer to MCLs is not an
appropriate consideration. In any event, restoring the Puente Valley aguifer(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 1 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

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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 1 and 2 would
comply with ARARs - the FS just 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.

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) (1) (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 there are no ARARs. It states that since this is an interim remedy,
drinking water standards will not be ARARs for aguifer 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 egual 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 uncontaminated
ground water and production wells.

PVSC Attachment A, Comment 79: Section 5.3, first paragraph - The in-situ ground water should
not he 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 1 and 2 as "low" in Section 5.3.2. The contaminant transport modeling and the water
guality data both show that there is no significant migration of contamination from the shallow
aguifer into the intermediate aguifer, nor is there significant migration of contamination from
the intermediate aguifer to the deep producing aguifer. A hydraulic gradient by itself is no
basis to conclude that there is significant contaminant transport through an aguitard.

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
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 of VOCs in ground water that discharges to San Jose

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Creek and pumping of the B7 wellfield are removing contamination from the system. Again,
EPA's evaluation of alternatives in the FS is contrary to the results of contaminant transport
modeling and reasonable interpretation of water guality 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 Alternatives 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 guantities. The FS notes and supports
facility-specific remediation of contamination in both the unsaturated and shallow saturated
zones.

PVSC Attachment A, Comment 83: Section 5.5.2 - All alternatives are essentially egual 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
achievement of proper RAOs, then all alternatives are also egual.

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 1 is properly not ranked for the
criterion of implementability. Alternative 2 is properly ranked higher than alternatives 3 and
4.

This section also deals with implementability issues surrounding water rights and discharge
options. The analysis should have conservatively recognized that these maybe 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 eguality 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 CERCIA 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 if RO
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 "would probably
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.

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 FS from 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 aguifer 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 Modeling), and replaces it with particle tracking presented in Appendix
B. The contaminant transport modeling conducted by the PVSC, which has been accepted by EPA and
is included in part of this FS, is much more accurate in predicting 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's particle tracking results to current
water guality data and the results of PVSCs contaminant transport modeling 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 reguires numerous
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 modeling 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 modeling
studies and presented in the original Appendix A.6 has been inappropriately deleted from the EPA
version.

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 aguifer zones are minimally
aerobic and not conducive to anaerobic dechlorination...". The revised text deletes the
minimally, and implies that the aguifers 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 PVSCs Section A. 6.7.1 PCE Migration, a bullet discussion
addressed the downgradient impact of a DNAPL source in the vicinity of MW6-4/6-5. 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 and B-21 referenced in Section B.3.2 for
the simulation of Alternative 2, these figures suggest that the B7 wellfield is operational.
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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 1            SAN GABRIEL VALLEY SUPERFUND SITE





 2        PUENTE VALLEY OPERABLE UNIT PROPOSED PLAN





 3





 4        TRANSCRIPT OF COMMUNITY MEETING on San Gabriel





 5  Valley Superfund Site Puente Valley Operable Unit





 6  Proposed Plan held at La Puente High School,





 7  15615 East Nelson Avenue, La Puente, California,





 8  Wednesday, January 28, 1998, at 7:10 P.M., before





 9  FRANCINE DI GIORGIO,  CSR No. 11404.





10





11





12  APPEARANCES:





13        ELIZABETH ADAMS





14               U.S. EPA Superfund Division





15        CATHERINE MC CRACKEN





16               U.S. EPA Office of Community Involvement





17        EUGENIA CHOW





18               U.S. EPA Remedial Project Manager,





19               Superfund Division





20        LOREN HENNING





21               U.S. EPA Remedial Project Manager,





22               Superfund Division





23        JON BISHOP





24               Los Angeles Regional Water Quality





25               Control Board








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 1  APPEARANCES (Continued.)





 2





 3        BRETT MOFFATT





 4               U.S. EPA Office of Regional Counsel





 5        DR. JACALYN SPISZMAN





 6               Department of Toxic Substances Control





 7        DOUG FRAZER





 8               U.S. EPA Remedial Project Manager,





 9               Superfund Division





10        BELLA DIZON





11               U.S. EPA Remedial Project Manager,





12               Superfund Division





13        RANDY WITTORP





14               U.S. EPA Media Relations Office





15        JON HARRIS





16               CH2M HILL





17





18





19





20





21





22





23





24





25








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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 guestions 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








          DEPO DEPOT CERTIFIED COURT REPORTERS (800) 891-7950

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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 guestions 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








          DEPO DEPOT CERTIFIED COURT REPORTERS (800) 891-7950

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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








          DEPO DEPOT CERTIFIED COURT REPORTERS  (800)891-7950

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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 durinq 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 qoinq to





 7  do is collect those before a short break, and we can





 8  qo throuqh them and take additional questions. That





 9  will help us move more efficiently.





10              There are two other items that you miqht





11  want to refer to durinq 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 durinq





14  the presentations and discussions on the back table





15  which may be helpful.





16              After the questions and answers we will





17  be takinq formal comments for the record. As you can





18  see, we have a court reporter here toniqht. This is





19  Francine. She's qoinq to be providinq us with a





20  transcript of the meetinq. 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 paqe 9 of the fax sheet, the local





25  libraries here and the Superfund Center in








          DEPO DEPOT CERTIFIED COURT REPORTERS (800) 891-7950

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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 guestions during





 9  presentations,  we'll be happy to cover them in the





10  guestions 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








          DEPO DEPOT CERTIFIED COURT REPORTERS  (800)  891-7950

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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








          DEPO DEPOT CERTIFIED COURT REPORTERS (800) 891-7950

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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








          DEPO DEPOT CERTIFIED COURT REPORTERS  (800) 891-7950

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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





 7  individual site investigations and in some cases





 8  reguiring 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








          DEPO DEPOT CERTIFIED COURT REPORTERS (800) 891-7950

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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








          DEPO DEPOT CERTIFIED COURT REPORTERS (800)  891-7950

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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 aguifer 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 period 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.





 8              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 aguifer to less contaminated areas or depths of





15  the aguifer; 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 reguired to evaluate a No Action Alternative





23  basically to provide a base for comparing all the





24  other alternatives. It answers the guestion:  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 guality 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              Both 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 reguirements.  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 guestions after break.





18             MS. MC CRACKEN: I think we will take a





19  ten-minute break. And if people do have guestions on





20  the guestion  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 guestion forms,  and we'll also





23  take other guestions 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 out of the hat.  It's:  "How





 2     does the EPP plan to comply with California





 3     Department of Health Services Memo 97-05 regarding





 4     the use of 'highly impaired,'  unguote,  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 qlossary 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 an 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 guestion 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 guestion 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 guestion 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 and answer those





11     two guestions.





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 guestions,  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     guestions that those who wrote down guestions 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     guestion. 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 guestion 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.





           DEPO DEPOT CERTIFIED COURT REPORTERS (800) 891-7950

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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 qround without pumpinq





 9     it and filterinq it and puttinq it back into the





10     qround? If I understand,  you're tryinq to qet it at





11     the mouth of the contamination portion of the area.





12     All that qroundwater runs where it can be probably





13     not be stopped but pumped out of the qround and





14     filtered before it qets to the mouth, otherwise you





15     have about five miles -- you said about five miles





16     accordinq to my sheet here -- and by my judqment





17     here, you have about five miles lonq 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 qet under there and





22     say, "We're qoinq to stop it here and qo another





23     way." It's like tryinq to stop water in the ocean,





24     tryinq to keep the warm current from runninq away.





25     How do you propose to do that? I don't know.





            DEPO DEPOT CERTIFIED COURT REPORTERS (800)  891-7950

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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 messinq up your question,





 7     but I think basically you want to know more





 8     specifically how are we actually qoinq to treat the





 9     water? How are we qoinq to clean? How are we qoinq





10     to address the qroundwater contamination? That's





11     your first question; riqht? 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 qive you an example





16     of what the treatment or what the action in the





17     alternative is that we are proposinq.





18                  We propose that extraction wells be





19     placed at the mouth of Puente Valley, so rouqhly in





20     this area here. That would be, the exact location of





21     those wells would be worked out probably -- well,





22     durinq the remedial desiqn. Those wells would





23     essentially pump water out from the qround and treat





24     it throuqh air strippinq, and that's basically where





25     we take water and allow air to flow throuqh it. What





           DEPO DEPOT CERTIFIED COURT REPORTERS (800)  891-7950

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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





              DEPO DEPOT CERTIFIED COURT REPORTERS (800)  891-7950

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 1     eastern part of the area there,  so that wells would





 2     be pumping contaminated water.  This is the eastern





 3     part.





 4                  MR.  BISHOP: I'll just answer that real





 5     quick: Is that, in the eastern part there aren't any





 6     production wells. The production wells are down in





 7     this area here, and they have treatment on them right





 8     now. And the proposed alternative would either use





 9     that treatment, incorporate that, or add new wells





10     in. The idea of the extraction is to have enough





11     extraction there to act as a barrier so that the





12     water doesn't continue on. It essentially becomes a





13     hydraulic barrier, and your question on perchlorate





14     that,  as far as I know, there is no perchlorate found





15     in this area.





16                  MR.  HENNING: Some of the production





17     wells, those wells in the B7 wellfield area, were





18     tested for perchlorate, and we did -- from those





19     tests there was one result that we did get one result





20     that indicated there was perchlorate there. It was





21     well below the state level of 18 parts per billion.





22     It was 6 parts per billion. We'll be sampling again





23     this month, but there are no known sources of





24     perchlorate in the Puente Valley Operable Unit. It's





25     unlikely that perchlorate will be an issue at





            DEPO DEPOT CERTIFIED COURT REPORTERS  (800) 891-7950

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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 naurally 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     guestions 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





            DEPO DEPOT CERTIFIED COURT REPORTERS (800) 891-7950

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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 guestion 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





            DEPO DEPOT CERTIFIED COURT REPORTERS (800)  891-7950

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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 it 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





           DEPO DEPOT CERTIFIED COURT REPORTERS  (800) 891-7950

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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 whether 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     guestions, before we start the official comments to





15     the record, I just wanted to explain how that works





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 guestions





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





            DEPO DEPOT CERTIFIED COURT REPORTERS (800) 891-7950

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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     guestion?





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





            DEPO DEPOT CERTIFIED COURT REPORTERS (800)  891-7950

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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





            DEPO DEPOT CERTIFIED COURT REPORTERS (800)  891-7950

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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 bad 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.





            DEPO DEPOT CERTIFIED COURT REPORTERS (800)  891-7950

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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





            DEPO DEPOT CERTIFIED COURT REPORTERS  (800)  891-7950

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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 guestion 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





            DEPO DEPOT CERTIFIED COURT REPORTERS (800)  891-7950

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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





            DEPO DEPOT CERTIFIED COURT REPORTERS (800) 891-7950

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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





17    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,  guote,





            DEPO DEPOT CERTIFIED COURT REPORTERS (800)  891-7950

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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, as 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





            DEPO DEPOT CERTIFIED COURT REPORTERS  (800) 891-7950

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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 drinkinq 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 drinkinq water source.





 8                 The qeneralized site description in the





 9    Proposed Plan suqqested that contaminated qroundwater





10    from the PVOU is flowinq throuqh Whittier Narrows and





11    into the Central Basin. As  EPA has acknowledqed,  no





12    miqration of contaminants from the PVOU to the





13    Whittier Narrows is occurrinq, 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 overdesiqn of the





18    remedy. There is no risk of exposure to contaminated





19    qroundwater 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 acknowledqe the substantial





23    role and benefit that facility-specific remedial





24    aqencies have already taken. At a number of the





25    facilities within the PVOU, the PRPs have undertaken





            DEPO DEPOT CERTIFIED  COURT REPORTERS (800)  891-7950

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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 guality.





 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 art 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





            DEPO DEPOT CERTIFIED COURT REPORTERS  (800) 891-7950

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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.





            DEPO DEPOT CERTIFIED COURT REPORTERS (800)  891-7950

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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 Watermaster is on record





            DEPO DEPOT  CERTIFIED COURT REPORTERS (800)  891-7950

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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    guestions 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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           DEPO DEPOT CERTIFIED COURT REPORTERS (800) 891-7950

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 1                       (Whereupon, at 9:00 P.M.,





 2              the community meeting was concluded.)





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          DEPO DEPOT CERTIFIED COURT REPORTERS  (800) 891-7950

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 1    STATE OF CALIFORNIA    )





 2                           )





 3    COUNTY OF LOS ANGELES  )





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 5                 I, FRANCINE DI GIORGIO, CSR No. 11404 in





 6    and for the State of California,  do hereby certify:





 7                 That said proceeding was taken down by





 8    me in shorthand at the time and place therein named,





 9    and thereafter reduced to typewriting under my





10    direction; and the same is a true, correct, and





11    complete transcript of said proceedings.





12                 I further certify that I am not





13    interested in the event of the action.





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               DEPO DEPOT CERTIFIED COURT REPORTERS (800) 891-7950

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