PB97-964511
EPA/541/R-97/133
January 1998
EPA Superfund
Record of Decision:
Modesto Groundwater Contamination
Modesto, CA
9/26/1997
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THE "MODESTO GROUND WATER CONTAMINATION" SITE
MODESTO, STANISLAUS COUNTY
CALIFORNIA
EPAID#: CAD 981997752
Interim Record of Decision
September 1997
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TABLE OF CONTENTS
Section Page
PART 1 — DECLARATION '. 1
1.1 SITE NAME AND LOCATION 1
1.2 STATEMENT OF BASIS AND PURPOSE 1
1.3 ASSESSMENT OF THE SITE 2
1.4 DESCRIPTION OF THE SELECTED REMEDY 2
1.4.1 Role of this Operable Unit within the Overall Site Strategy 3
1.4.2 Major Components of the Selected Remedy 3
1.5 STATUTORY DETERMINATIONS 5
PART 2 — DECISION SUMMARY 6
SECTION 1 SITE NAME, LOCATION, AND DESCRIPTION 6
SECTION 2 SITE HISTORY AND ENFORCEMENT ACTIVITIES 9
SECTION 3 HIGHLIGHTS OF COMMUNITY PARTICIPATION 13
SECTION 4 SCOPE AND ROLE OF INTERIM REMEDIAL ACTION WITHIN
SITE STRATEGY 14
SECTION 5 SUMMARY OF SITE CHARACTERISTICS 16
5.1 Site Geology and Hydrogeology 16
5.2 PCE Sources and Migration Pathways 21
5.3 Groundwater Results 24
5.4 Soil Results 28
5.5 Soil Gas Results 28
5.6 Potential for Presence of DNAPL 30
5.7 Radionuclides 31
SECTION 6 SUMMARY OF SITE RISKS 31
6.1 Risk Assessment 31
6.2 Rationale for the Limited Scope of the Action 35
6.3 Risks of an Interim Action 36
SECTION 7 DESCRIPTION OF ALTERNATIVES 36
7.1 The Selection of Treatment Technologies and Development of Alternatives .... 36
7.2 Groundwater 36
7.3 Soils 40
7.4 Assembly of Alternatives 41
7.4.1 Alternative 1: Groundwater Extraction and Treatment (4 Extraction
Wells); Monitoring and Evaluation of Downgradient Edges of the
Plume 42
7.4.2 Alternative 2: SVE and Groundwater Extraction and Treatment (4
Extraction Wells); Monitoring and Evaluation of Downgradient
Edges of the Plume 44
7.4.3 Alternative 3: Air Sparging, SVE, and Groundwater Extraction and
Treatment (4 Extraction Wells); Monitoring and Evaluation of
Downgradient Edges of the Plume 48
7.4.4 Alternative 4: Groundwater Extraction and Treatment of Main Source
Area (1 Extraction Well); Monitoring and Evaluation of Downgradient
Edges of the Plume 49
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TABLE OF CONTENTS (cont'd)
Section
7.4.5 Alternative 5: SVE and Groundwater Extraction and Treatment of
Main Source Area (1 Extraction Well); Monitoring and Evaluation of
Downgradient Edges of the Plume 50
7.4.6 Alternative 6: Air Sparging, SVE, and Groundwater Extraction and
Treatment of Main Source Area (1 Extraction Well); Monitoring
and Evaluation of Downgradient Edges of the Plume 51
7.4.7 Alternative 7: No Action 52
SECTION 8 ARARs 53
8.1 Definition of ARARs 53
8.2 Discussion of ARARs 54
SECTION 9 SUMMARY OF THE COMPARATIVE ANALYSIS 57
9.1 Comparison of Alternatives 57
9.1.1 Overall Protection of Human Health and the Environment 57
9.1.2 Compliance with ARARs 59
9.1.3 Long-Term Effectiveness and Permanence 59
9.1.4 Reduction of Toxicity, Mobility, or Volume 60
9.1.5 Short-Term Effectiveness 61
9.1.6 Implementability 61
9.1.7 Cost 62
9.1.8 State Acceptance 63
9.1.9 Community Acceptance 64
SECTION 10 THE SELECTED REMEDY 64
SECTION 11 STATUTORY DETERMINATIONS 75
11.1 Protectiveness 75
11.2 Compliance with ARARs 75
11.3 Cost-Effectiveness 76
11.4 Use of Permanent Solutions, Alternative Treatment, or Resource Recovery
Technologies 76
11.5 Preference for Treatment as a Principle Element 76
SECTION 12 DOCUMENTATION OF SIGNIFICANT CHANGES 76
PART 3 - RESPONSIVENESS SUMMARY 78
PART 4 - BIBLIOGRAPHY 82
Appendix
A INDEX OF DOCUMENTS IN THE ADMINISTRATIVE RECORD A-l
B APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
in
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TABLE OF CONTENTS (cont'd)
Section Page
(ARARS) B-2
IV
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LIST OF FIGURES
Figure Page
1-1 SITE LOCATION MAP 7
1-2 WELL LOCATION MAP 8
5-1 CROSS-SECTION A - A' 17
5-2 CROSS-SECTION B - B' 18
5-3 CROSS-SECTIONS LOCATION MAP 19
5-4 GROUNDWATER ELEVATION - MARCH 15, 1996 22
5-5 HIGHEST PCE CONCENTRATIONS IN SOIL 26
5-6 PCE CONCENTRATIONS IN GROUNDWATER (AUGUST 1995) 29
10-1 SCHEMATIC ILLUSTRATION OF THE SELECTED REMEDY 70
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LIST OF TABLES
Table
2-1 SUMMARY OF REMEDIAL INVESTIGATION ACTIVITIES
AND RESULTS 11
5-1 GENERAL WATER QUALITY PARAMETERS, PHASE III RI 20
5-2 HISTORICAL PCE CONCENTRATIONS IN GROUNDWATER
PHASE III RI 25
5-3 SUMMARY OF SOIL GAS ANALYTICAL DATA, PHASE III RI 30
5-4 SUMMARY OF RADIONUCLIDES IN GROUNDWATER SAMPLES
PHASE III RI 32
6-1 SUMMARY OF ESTIMATED RISK VALUES BASELINE HUMAN
HEALTH RISK ASSESSMENT, MODESTO GROUND WATER
CONTAMINATION SITE 34
7-1 ESTIMATED SVE PARAMETERS FOR ALTERNATIVES 2 AND 5 47
9-1 SUMMARY OF INDIVIDUAL EVALUATIONS OF FINAL
ALTERNATIVES 65
VI
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LIST OF ACRONYMS
ARARs
bgs
CERCLA
DHS
DNAPL
DTSC
E&E
EPA
FASP
FS
GAC
gpm
>
H2O
IRA
IROD
MCL
MSL
MW
NCP
PCE
ppb
ppm
pCi/L
PP
PRP
psig
RA
RD/RA
RI
RI/FS
ROD
RWQCB
SARA
scftn
SVE
TDS
applicable or relevant and appropriate requirements
below ground surface
Comprehensive Environmental Response, Compensation and Liability Act
California State Department of Health Services
denser-than-water nonaqueous-phase liquid
California State Department of Toxic Substances Control
Ecology and Environment, Inc.
U.S. Environmental Protection Agency
field analytical support project
feasibility study
granular activated carbon
gallons per minute
greater than
water
interim remedial action
interim record of decision
maximum contaminant level
mean sea level
monitoring well
National Oil and Hazardous Substances Pollution Contingency Plan
tetrachloroethene
parts per billion
parts per million
pico Curies per liter
Proposed Plan
potentially responsible party
pounds per square inch gauge
risk assessment
remedial design/remedial action
remedial investigation
remedial investigation/feasibility study
record of decision
California State Regional Water Quality Control Board
Superfund Amendments and Reauthorization Act
standard cubic feet per minute
soil vapor extraction
Total Dissolved Solids
micrograms per liter
VII
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PART 1 — DECLARATION
SECTION 1
1.1 SITE NAME AND LOCATION
The "Modesto Ground Water Contamination" Site
Modesto, Stanislaus County
California
EPAID#: CAD 981997752
1.2 STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected interim remedial action (IRA) for the Modesto
Ground Water Contamination Site in Modesto, Stanislaus County, California, which was chosen in
accordance with the Comprehensive Environmental Response, Compensation, and Liability Act of
1980 (CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986
(SARA), and, to the extent practicable, the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP). This decision is based on the administrative record for the site.
The State of California, through the California Environmental Protection Agency (Cal-EPA)
Department of Toxic Substances Control (DTSC) and the Regional Water Quality Control Board
(RWQCB), concurs with the selected remedy.
Releases of tetrachloroethene (PCE) from a leaking dry cleaning machine at the dry cleaning
establishment and the sanitary sewer line leading from the dry cleaning establishment have contami-
nated groundwater at the Modesto site with volatile organic contaminants (VOCs).
An interim, rather than final, Record of Decision (ROD) was developed because of uncertain-
ties over whether any available remedial approach is capable of achieving groundwater cleanup
standards throughout the plume, and the necessity of further delineating the downgradient edges of the
plume. Upon commencing the RD/RA, U.S. Environmental Protection Agency (EPA) will collect
additional data to determine if federal and state requirements can be met throughout the groundwater
plume and to better delineate the plume. This data collection activity will also provide valuable
information to determine what future actions are appropriate. EPA will select a final remedy that will
achieve appropriate clean up levels or EPA will demonstrate that a waiver of these standards is
justified. With this in mind the specific IRA objectives, in addition to those stated above, are as
follows:
• Eliminate and contain the highest contaminant levels at the source (source
control).
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• Prevent exposure to contaminated groundwater, above acceptable risk levels,
to protect human health and the environment.
• Minimize the impact of interim cleanup measures to the community.
• Collect data to determine if federal and state requirements can be met
throughout the aquifer.
• To delineate more clearly the downgradient edges of the plume and to
prevent its further migration.
This interim remedial action will provide source control, which will hydraulically contain the highest
contaminant levels. Contaminants will also be removed and treated during this interim action.
1.3 ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this site, if not addressed by
implementing the response actions selected in this Interim Record of Decision (IROD), may present
an imminent and substantial endangerment to public health, welfare or the environment.
1.4 DESCRIPTION OF THE SELECTED REMEDY
This alternative calls for the design and implementation of an interim remedial action to
protect human health and the environment. The goals of this remedial action are to:
1) eliminate and contain the highest contaminant levels at the source [source
control];
2) prevent exposure to contaminated groundwater, above acceptable risk levels,
to human health and the environment;
3) minimize the impact of interim cleanup measures to the community;
4) collect data to determine if federal and state requirements can be met
throughout the aquifer; and
5) to delineate more clearly the downgradient edges of the plume and to prevent
its further migration.
During the IRA, operation of the extraction well will draw groundwater in the most contaminated,
source-area portions of the plume to the well, thus inhibiting downgradient migration of those source-
area contaminants.
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1.4.1 Role of this Operable Unit within the Overall Site Strategy
The overall objectives of the interim remedial action (IRA) at the Modesto Ground Water
Contamination Site are to eliminate and contain the highest contaminant levels at the source (source
control) and to prevent potential exposure of human or environmental receptors to PCE or other
organic compounds (e.g., toluene) released to the soil and groundwater. EPA will collect data on the
aquifer, and contaminant response to the remediation measures. The aquifer remedial goals will be
determined in a final ROD for the site. This remedial action will be monitored carefully to determine
the feasibility of achieving these goals and to ensure that hydraulic control of the contaminated plume
is maintained. After a period of approximately 18 to 24 months, EPA will arrive at a final decision
for the site, and a final ROD for groundwater, which specifies the ultimate goal, remedy and
anticipated remediation timeframe, will be prepared. This interim system may be incorporated into
the design of the site remedy specified in the final action ROD.
Although reference is typically to PCE contamination, all remedial alternatives will address
each of the organic contaminants known to be present. PCE had previously been detected in
groundwater extracted by Modesto's Municipal Well 11. However, since this well has been taken out
of service, there currently is no known exposure to contaminants from this well. If not treated,
contaminants may continue to migrate from the source areas and may potentially impact operating
municipal wells throughout the city. Furthermore, this aquifer is considered viable for use as
drinking water in the event that additional wells are installed in the affected parts of the aquifer.
1.4.2 Major Components of the Selected Remedy
The primary components of the selected remedy include groundwater extraction, groundwater
treatment by air stripping with carbon adsorption, discharge of treated groundwater to the City of
Modesto's water system, and soil vapor extraction (SVE) followed by carbon adsorption. The
selected alternative is expected to remove a substantial portion of dissolved PCE from the groundwa-
ter. EPA will be monitoring the downgradient edge of the plume to determine if the remaining PCE
would be removed through natural attenuation. If necessary to comply with discharge requirements,
extracted groundwater will also be treated using an ion exchange unit to remove naturally occurring
uranium.
These components are summarized as follows:
• Groundwater Extraction - A pumping rate of 50 gallons per minute (gpm),
which includes one or more extraction wells, will be used to achieve a
capture zone of approximately 250 to 300 feet. This will remove the most
contaminated groundwater near the source area and hydraulically isolate this
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area from the surrounding aquifer. EPA will be monitoring the downgradient
edge of the plume to determine if natural attenuation is occurring since there
will be no continuing source of contamination.
• Groundwater Treatment by Air Stripping - Air stripping is a simple,
straightforward technology to transfer volatile organic compounds from a
dissolved liquid phase to a vapor phase. Air will be sparged into a packed
column or shallow trays designed to maximize interfacial surface area and
shear, resulting in high mass transfer rates. The solvent-laden gas will then
pass over a bed of activated carbon to remove PCE and other organic vapors
from the off-gas stream.
• Discharge of Treated Groundwater - Pending approval of a groundwater
discharge permit by the City of Modesto, treated groundwater will be
discharged to the sewer system. Although uranium is naturally occurring,
and is a regional feature unrelated to this site for which cleanup standards are
not required, additional treatment of extracted groundwater to remove
uranium may be necessary in order to satisfy groundwater disposal require-
ments. Treatment may be required to meet the City of Modesto's uranium
pretreatment requirements if disposal is to the City of Modesto's sewer
system, or the drinking water standards if treated water is supplied to the
City of Modesto's drinking water system.
• Soil Vapor Extraction - SVE in the vadose zone will be used to increase the
rate of removal of contaminants that are diffusing from the groundwater to
the vadose zone. SVE removal efficiency will be evaluated through the IRA.
Some SVE wells will be screened near the water table to achieve effective
removal. The solvent laden gas would then pass over a bed of activated
carbon to remove PCE and other organic vapors from the off-gas stream.
Based on data collected during the IRA, EPA will calculate the threat to
groundwater from the soil. EPA will also calculate the extent to which the
SVE system accelerates groundwater cleanup. EPA will cease SVE when the
soil no longer poses a threat to groundwater and no longer accelerates
contaminant removal from groundwater.
• Institutional Controls - Institutional controls will include signing and
fencing around the treatment area. These institutional controls will be
maintained for the duration of treatment, and the need for additional institu-
tional controls will be evaluated in the final remedy.
EPA will develop a final remedial action that will address the applicable aquifer cleanup
standards. EPA will select a final remedy that will achieve appropriate groundwater cleanup levels or
EPA will demonstrate that a waiver of these standards is justified.
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1.5 STATUTORY DETERMINATIONS
This IRA is protective of human health and the environment complies with federal and state
applicable or relevant and appropriate requirements (ARARs) for this limited-scope action, and is
cost-effective. Although the scope of this IRA is not intended to fully address the statutory mandate
for permanence and treatment to the maximum extent practicable, the IRA utilizes treatment and thus
is in furtherance of that statutory mandate. Although this is an interim action, the statutory
preference for remedies that employ treatment that reduce toxicity, mobility, or volume as a principal
element, are partially addressed in this remedy and will be addressed by the final response action.
Subsequent actions are planned to fully address the threats posed by the conditions at this site.
Because this remedy will result in hazardous substances remaining on-site above health based levels, a
review will be conducted within 5 years after commencement of the remedial action to ensure that the
remedy continues to provide adequate protection of human health and the environment. Because this
is an interim action ROD, review of this site and of this remedy will be continuing as EPA continues
to develop final remedial alternatives for the site.
Keith A. Takata Date
Director, Superfund Division
*****
EPA Region IX
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PART 2 - DECISION SUMMARY
SECTION 1 SITE NAME, LOCATION, AND DESCRIPTION
The Modesto Ground Water Contamination Superfund site is located in Modesto, Stanislaus
County, California. The site was included on the final National Priorities List on March 31, 1989.
The site initially included Municipal Well Number 11 (Well 11), which is contaminated with PCE
above the federal and state maximum contaminant level (MCL) of 5.0 parts per billion (ppb), and
potential groundwater contamination sources that may contribute to groundwater degradation in the
Well 11 's zone of influence. Well 11, located at the corner of Magnolia and Mensinger Avenues, is
owned by the City of Modesto. The site is currently defined to include contaminant sources.
Through the RI and other investigations, Halford's Cleaners located at 941 McHenry Avenue, was
determined to be the primary source of PCE contamination at Well 11. The immediate area around
Halford's Cleaners and the proposed extraction well location is light industrial and residential. This
land use is consistent with projected future land use. If contaminated groundwater entered the
Modesto municipal system through one of its supply wells, as many as 150,000 residents could be
affected.
The City of Modesto is located in Stanislaus County, approximately four miles south of the
Stanislaus River and five miles west of the Tuolumne River in the San Joaquin Valley. The city
encompasses approximately 12 square miles and has a population of approximately 170,000. Major
industries include canneries; wineries; and dairy, meat, poultry, and frozen food processing plants.
The climate is characterized by hot, dry summers and mild winters. The mean annual
precipitation is 12 inches with 87 percent of this occurring between October and May. Groundwater
is the primary source of supply for municipal, industrial, and agricultural water use in the City of
Modesto. Water supplies include 49 wells owned by the City of Modesto, 62 owned by the Del Este
Water Company, and numerous private domestic wells.
A site location map is presented as Figure 1-1 and a well location map is presented as Figure
1-2. The investigation area lies at an approximate elevation of 90 feet above mean sea level (MSL).
The site and vicinity are nearly flat with a gentle slope to the west at a gradient of approximately
0.001.
Dry Creek, a naturally occurring stream located approximately one mile to the southeast, is
the closest drainage to the site. Dry Creek flows west to the Tuolumne River, a tributary to the San
Joaquin River. Water delivery laterals extend from the Modesto Main Canal and run east-west at
distances of 0.8 mile to the north and 0.3 mile to the south of the site (see Figure 1-2).
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Base map source: USGS 1:2-1.000 Riverbank (PR 1987) and Salida (PR 1987). CA quadrangles
Ecology and Environment. Inc.
Figure I -1
SITE LOCATION MAP
Modesto Groundwater Contamination Site
ZS6IOI.97.a (Zip) 07/3U«t.
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(WNU.4WIR0
MEHSINGEFt AVENUE
MW-7
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Ool Furniture
MJxtSoaeoui Shop
WEST FAIRMONT AVE
MW-
Bk'i lodge
.MW-1_
I I'm kirn)
SV-
MW-
HoHoid's
Cleoners
SV-2 and _% | totomMIe Dalmly
MW-8 '
private property
GR1SWOLD
Stop
MW-4
AVENUE
UJ
DM Parts
Home
SoMen
Stole
Aulo
UJ
S
Ul
tt
Ul
I
0
5
r
Hfr
0 50 100 200 300 feet
Approximate well location
©1997 Ecology and Environment. Inc.
Figure 1-2
WELL LOCATION MAP
Modesto. California
ZS6IOI.n (ZIP) 07/31/97
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SECTION 2 SITE HISTORY AND ENFORCEMENT ACTIVITIES
Contamination at Well 11 was initially detected in September 1984, due to PCE contamination
in Well 11 at 16.7 ppb, which is above the federal and state MCL of 5 ppb. Well 11 was 1 of 12
wells initially sampled by the City of Modesto under the provisions of California Assembly Bill 1803.
Within a few weeks after contamination was detected in Well 11, local regulatory agency representa-
tives raised the possibility of Halford's Cleaners being a source of the PCE contamination. Halford's
Cleaners was suspected because of its proximity to Well 11 (approximately 1,000 feet southeast), and
the likely use of PCE at the cleaning facility. In April 1985, the Stanislaus County Department of
Environmental Resources conducted a groundwater investigation in the immediate vicinity of
Halford's Cleaners, which included sampling an inactive air conditioning well at the Elks Lodge,
approximately 100 feet northwest of Halford's Cleaners. Results indicated 84.6 ppb PCE in
groundwater from the Elks Lodge well. Following the groundwater investigation, the county
collected two soil samples (at 16 inches and 32 inches) at Halford's Cleaners in the area near a dry
cleaning machine. Results revealed a maximum PCE concentration in soil of 176,000 ppb.
After being deactivated in 1984 when PCE contamination was initially detected, Well 11 was
reactivated in April 1987, after continuous monitoring indicated no detectable levels of PCE or other
chlorinated solvents. In February 1989, Well 11 was again taken out of service after concentrations
of 8.28 ppb PCE were detected in December 1989. The well remained out of service until a
wellhead Granular Activated Carbon (GAC) treatment system was installed by the City of Modesto in
May 1991. Well 11 was returned to service in June 1991 and operated until October 1995 when the
City indefinitely deactivated it due to naturally occurring levels of uranium above the MCL of 20 pico
Curies per liter (pCi/L).
In August 1985, the City of Modesto collected sludge and sediment samples from sewer lines
to the north and south of Halford's Cleaners. A maximum concentration in sludge of 1,360 ppb PCE
was found in the main sewer line immediately downgradient from the connection with the private
service line originating from Halford's Cleaners.
In 1987, Radian Corporation, under contract to the California Department of Health Services
(DHS), conducted an investigation of potential groundwater contaminant sources in Modesto.
Objectives of the DHS/Radian investigation were to identify businesses that potentially use PCE and
could be associated with contamination of 10 Modesto domestic water supply wells; identify
previously unknown surface contamination; evaluate potential health risks associated with the drinking
water supply and potential contaminant sources; and develop a list of remedial alternatives. Results
indicated that 106 businesses warranted further investigation as potential contaminant sources.
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Follow-up evaluations eliminated 73 businesses from the 106, leaving 34 which were considered for
soil gas sampling.
During the Phase 1 remedial investigation, EPA investigated 17 of the 34 commercial sites in
the City of Modesto that were possible sources of PCE contamination that had been detected at Well
11. Seventeen were eliminated because they were not within one mile of Well 11; one mile was
selected as a conservative estimate of Well 11's radius of influence. Although significant levels of
PCE were detected at four separate dry cleaning facilities, only Hal ford's Cleaners was located within
the radius of influence of Well 11, which was determined via a pump test to be 1,750 feet. Well 11
is located approximately 0.25 mile northwest of the Halford's Cleaners location.
In December 1989, EPA's Emergency Response Section collected soil and soil gas samples
in the vicinity of Halford's Cleaners. Results of five samples at approximately 5.8 feet bgs indicated
a maximum of 6,050 parts per million (ppm) PCE in the soil near the northwest corner of the
building at Halford's and an elevated PCE concentration of 1,965 ppm in soil gas adjacent to the
automobile dealership immediately south of Halford's Cleaners. Both soil and soil gas data indicated
lower PCE concentrations away from Halford's Cleaners.
A second EPA Emergency Response Section investigation in July 1990 consisted of drilling
and sampling six boreholes in the vicinity of Halford's Cleaners, and sampling the neighboring Elks
Lodge well. The highest PCE concentrations in soil (up to 21,000 ppb) were within five feet of the
surface at the borehole closest to Halford's Cleaners. Groundwater sample results from the Elks
Lodge well indicated PCE at 73 ppb. EPA will contact the owner/operator of the Elk's Lodge well to
discuss abandoning (sealing off) this well during the IRA.
In March and April of 1990 the RWQCB conducted a soil gas investigation to delineate
potential contaminant plumes associated with City of Modesto Wells 11, 14, and 21. Investigation
results indicated that the "Halford Plume," just west of McHenry Avenue and south of Roseburg
Avenue, is affecting Well 11. Discharges from Halford's Cleaners to the sewer line are the source of
contamination. Halford's Cleaners is believed to be the source of this plume.
On September 25, 1990, the EPA Emergency Response Section issued an order to the
Halford's Cleaners PRPs for treatment of contaminated soil at the Halford's site. The removal action
was initiated in February 1991. An SVE system was installed at Halford's Cleaners in February
1991. The system was operated until the rate of removal had diminished. EPA determined that a
larger SVE system was required to adequately address the extent of contamination.
EPA began the RI in 1991 to more completely define the extent of soil and groundwater
contamination, and to obtain information necessary for the FS and RA. The RI was conducted in
three phases; a summary of specific objectives and conclusions of each phase is presented in
10
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Table 2-1
SUMMARY OF REMEDIAL INVESTIGATION ACTIVITIES AND RESULTS
Phase 1 RI Activity
Area wide soil gas survey to locate potential sources
of PCE contamination that could impact Municipal
Well 11.
Soil sampling near Halford's Cleaners. Soil samples
collected while drilling four new monitoring wells.
Ground water sampling in four monitoring wells.
Aquifer pump test to determine the radius of
influence for Municipal Well 11.
Phase 2 RI Activity
Soil gas survey in the immediate vicinity of Halford's
Cleaners.
Groundwater sampling in four monitoring wells.
EPA performs a Human Health Risk Assessment.
Phase 3 RI Activity
Groundwater sampling in existing monitoring wells
and five new wells.
Soil gas sampling at Halford's Cleaners.
EPA revises Human Health Risk Assessment to
include Phase 3 RI data.
Result
Halford's Cleaners is the major source of
contamination at Municipal Well 1 1 .
The highest levels of PCE contamination were found
at or below the water table.
PCE was found in each groundwater monitoring
well. Highest PCE level is 2,800 ppb in monitoring
well MW-4 near Halford's Cleaners.
Halford's Cleaners is within die radius of influence
for Municipal Well 11, which is 1,000 feet away.
Result
PCE is present in small quantities in the soil gas near
Halford's Cleaners and the adjacent sewer line.
Highest PCE level is 4,200 ppb in monitoring well
MW-3 near Halford's Cleaners.
Groundwater extracted at the source area, near
Halford's Cleaners, would not be safe to drink;
currently it is not a drinking water source.
Result
Highest PCE level is 74,000 ppb in monitoring well
MW-8 at Halford's Cleaners. Toluene is also
present at MW-8 at 13,200 pg/L. Uranium
concentration exceeded MCLs at most wells.
PCE is present in all samples.
Final Risk Assessment conclusions are consistent
with the initial conclusions.
11
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Table 2-1. Before conducting the first phase of the RI, EPA notified parties potentially responsible
for the remediation of the site that, unless they objected, EPA would itself conduct the RI/FS rather
than using the settlement procedures under CERCLA Section 122. EPA had previously sent general
notices to these PRPs, but has not sent special notices.
EPA had previously considered a remedial alternative that used well-head treatment of water
collected in Well 11. However, because the City's municipal wells may not always be operating
(i.e., Well 11 has been shutdown due to high concentrations of naturally occurring uranium), this
approach cannot be relied upon to ensure remediation goals are achieved.
12
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SECTION 3 HIGHLIGHTS OF COMMUNITY PARTICIPATION
The public was encouraged to participate in the selection of the interim remedy for the
Modesto Ground Water Contamination Site during a public comment period from July 14 to August
13, 1997. The Proposed Plan presented seven alternatives, considered by EPA, DTSC and the City of
Modesto to address groundwater contamination. The Proposed Plan was released to the public on July
14, 1997, and copies were sent to all known interested parties, including elected officials and
concerned citizens.
The Proposed Plan summarized available information regarding the site. Additional materials
were placed in the information repository at the Stanislaus County Free Library. The Administrative
Record, which includes materials considered or relied on in the selection of the remedial action, is
located at the information repository. The public is welcome to inspect materials in the Administrative
Record and the information repository during business hours.
Interested citizens were invited to comment on the Proposed Plan and the remedy selection
process by mailing comments to the EPA Remedial Project Manager, by calling a toll-free phone
number to record a comment, or by attending and commenting at a public meeting on July 29, 1997.
Display advertisements in the Modesto Bee included information regarding the information
repositories, the toll-free telephone line, and an address for submitting written comments.
The Responsiveness Summary, Part 3 of this document, summarizes and addresses public
comments on the Proposed Plan.
This decision document presents the selected IRA, chosen in accordance with CERCLA as
amended by the Superfund Amendments and Reauthorization Act (SARA) of 1986, and, to the extent
practicable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). The
decision is based on the Administrative Record; an index to the documents contained in the Adminis-
trative Record is provided in Appendix A.
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SECTION 4 SCOPE AND ROLE OF INTERIM REMEDIAL ACTION WITHIN SITE
STRATEGY
This section includes the rationale for conducting the IRA, the scope of the IRA, and potential
future remedial actions at the Modesto Ground Water Contamination Site. Interim actions are
specified by EPA under two scenarios, both of which apply to the Modesto Ground Water Contami-
nation Site:
• To prevent further plume migration and initiate cleanup while RI/FS and post
RI/FS activities are being completed; and
• To obtain information about the response of the aquifer to remediation
measures in order to define final cleanup goals that are practicable for the
site.
While the groundwater contamination is being contained during the IRA, this action will be
monitored carefully to determine the feasibility of achieving groundwater cleanup standards through-
out the aquifer for the final remedial action. It is EPA's goal to determine a final remedial decision
for this site within 18 to 24 months from implementing the IRA. With this in mind, the specific IRA
objectives, in addition to those stated above, are as follows:
• Eliminate and contain the highest contaminant levels at the source (source
control).
• Prevent exposure to contaminated groundwater, above acceptable risk levels,
to protect human health and the environment.
• Minimize the impact of interim cleanup measures to the community.
• Collect data to determine if federal and state requirements can be met
throughout the aquifer.
• Delineate more clearly the downgradient edges of the plume and to prevent
its further migration.
The IRA involves groundwater extraction at the source area near Halford's Cleaners and
treatment of the water by air stripping. Pending approval of a groundwater discharge permit by the
City of Modesto, treated groundwater will be discharged to the sewer system. Although uranium is
naturally occurring, and is a regional feature unrelated to this site for which cleanup standards are not
required, additional treatment of extracted groundwater to remove uranium in order to satisfy
groundwater disposal requirements may be necessary. Treatment may be required to meet the City of
14
-------
Modesto's uranium pretreatment requirements, if disposal is to the City of Modesto's sewer system;
or to MCLs if treated water is supplied to the City of Modesto's drinking water system. EPA will
monitor groundwater for uranium to determine if treatment for uranium is necessary.
In addition to directly treating the groundwater by air stripping, an SVE system will also be
installed to remove PCE from the groundwater via the vadose zone. The solvent-laden gas from the
air stripper and the SVE system will be passed over a bed of activated carbon to remove PCE and
other organic vapors from the off-gas stream.
The IRA is expected to remove 90-to-95 percent of dissolved PCE from the groundwater;
EPA will monitor the downgradient edge of the plume to determine if the remaining dissolved PCE
will be removed through natural physical mechanisms (i.e., natural attenuation). If monitoring
reveals that natural attenuation is not occurring, the edges of the plume will be addressed in the final
remedy. Specifically, one or more downgradient extraction wells will likely be installed.
As part of the preferred alternative, EPA will collect additional data to determine whether
other measures are necessary to achieve groundwater cleanup standards within a reasonable
timeframe. At this time, EPA need not meet MCLs in the aquifer because these standards are outside
the scope of this IRA.
EPA's expectations for a final remedy include returning the groundwater to its beneficial uses
to the extent practicable within a reasonable timeframe given the circumstances at the site, and the
elimination of potential risks to human health and the environment. By reducing source area
contaminant and contaminate migration through groundwater extraction and treatment and SVE, this
IRA will be fully consistent with EPA's expectations and remedial goals for this site.
15
-------
SECTION 5 SUMMARY OF SITE CHARACTERISTICS
5.1 Site Geology and Hydrogeology
Fresh ground water occurs in two aquifer systems in the Modesto area: a semi-confined
(upper) aquifer above the Corcoran Clay, and a confined (lower) aquifer, which lies below the
Corcoran Clay and extends to a depth of approximately 700 feet bgs. The semi-confined upper
aquifer includes both younger and older alluvium deposits. The confined lower aquifer includes the
older alluvium and unconsolidated continental deposits. Where the Corcoran Clay pinches out, the
upper and lower aquifers are hydrologically interconnected. The Corcoran Clay is an important
aquitard, or confining layer, southwest of this site, and separates the water table aquifer above it from
the regional confined aquifer below it. It has been reported that the Corcoran Clay pinches out near
the site and interfingers with sand near its edge. The upper aquifer is used as a drinking water
source, although there are no known active drinking water wells in the immediate vicinity of the site,
and Municipal Well 11 is currently not in use. Sediments encountered during drilling at the Modesto
site are typical of alluvial fan deposition in the San Joaquin Valley. The sediments consist of
discontinuous interbedded sands, silts, and clays. The beds or layers encountered while drilling were
usually less than ten feet thick. Most of the sand encountered was fine-to medium-grained, with
occasional coarser sand units present.
As seen in the generalized cross-sections in Figures 5-1 and 5-2, most of the sedimentary
layers are discontinuous across the site. Figure 5-3 shows the locations of the cross-sections. Many
of the sedimentary changes are gradual, grading from sands to silty sands to sandy silts. As seen in
Figures 5-1 and 5-2, sediments near the water table in the lithologic logs for MW-4 and MW-6 are
fine-grained. Sediments to the north are coarser grained (MW-2, MW-7, and MW-9). .
A predominantly fine-grained layer, silty clay to clayey silt with thin sand interbeds, was
encountered at approximately 95 to 145 feet bgs while drilling the borehole for MW-9. Whether this
is the Corcoran Clay is unknown. Sediments from the fine-grained layer in MW-9 were described as
olive or light olive brown, while the Corcoran Clay has been described as gray or blue in color
(Balding and Page, 1973). MW-9 is screened below this fine-grained layer from 144 to 154 feet bgs,
while all other monitoring wells are screened above it, from 60 to 90 feet bgs.
General mineral analysis of groundwater samples indicate the water from MW-9 is similar to
water from nearby MW-8 (Table 5-1). The presence of PCE in both MW-8 and MW-9 indicates that
some lateral migration likely occurs. However, the concentration of PCE was 74,000 ptg/L in a
groundwater sample from MW-8 (screened at _+ 80 feet bgs), but only 40 /zg/L from MW-9 located
16
-------
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-------
MENSINGER AVENUE
MW-7
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jttortftweow Stopj
WEST . FAIR MONT AVE
ltn Parts
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GR IS WOLD I AVENUE
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0 SO 100 200 300 feet
Approximate well location
©1997 Ecology and Environment. Inc.
Figure 5-3
CROSS-SECTIONS LOCATION MAP
Modesto, California
ZS6IOI.b (ZIP) 07/31/97
-------
Table 5-1
GENERAL WATER QUALITY PARAMETERS, PHASE HI RI
Fluoride
Chloride
Nitrite-N
Bromide
Nitrate-N
Ortho-Phosphate P
Sulfate
Total Alkalinity (as CaCO3)
Hardness
Sulfide
Ammonia
Total Organic Carbon (TOC)
Chemical Oxygen Demand (COD)
Biochemical Oxygen Demand
(BOD)
Total Dissolved Solids (TDS)
Total Suspended Solids (TSS)
Concentration (mg/L)
MW-1
<0.4
46.7
<0.02
0.13 L,J
12.1
<0.06
28.1
294
312
<1.0
<0.1
10.8
<20.0
<4J
558 J
<10J
MW-2
<0.4
45.6
<0.02
0.13 L,J
11.0
<0.06
27.6
300
336
<1.0
<0.1
9.3
<20.0
<4J
559 J
<10J
MW-3
<0.4
36.3
<0.02
0.19 L.J
11.3
0.10L.J
25.5
310
302
<1.0
<0.1
13.0
<20.0
<4J
916 J
75 J
MW-4*
<0.4
16.8
<0.02
0.10 L.J
6.4
<0.06
22.4
230
214
<1.0
<0.1
6.2
<20.0
<4J
380 J
<10J
MW-S
<0.4
76.1
<0.02
0.19 L.J
12.2
<0.06
22.8
284
378
<1.0
<0.1
9.5
<20.0
<4 J
630 J
325 J
MW-6
<0.4
98.9
<0.02
0.27 L.J
4.5
<0.06
46.4
470
470
<1.0
<0.1
11.7
<20.0
<4J
789 J
<10J
MW-7
<0.4
76.2
<0.02
0.19 L,J
17.0
<0.06
38.3
429
486
<1.0
<0.1
14.0
<20.0
<4J
798 J
<10J
MW-8
<0.4
36.4
0.02
0.10 L,J
10.2
<0.06
16.7
298
312
<1.0
<0.1
8.5
<20.0
<2J
478
3> H
MW-9
<0.4
24.1
<0.02
0.06 L.J
5.4
<0.06
11.5
194
196
<1.0
<0.1
4.5
<20.0
<2J
346
<10J
WeU 11
<0.4
46.8
<0.02
0.10 L.J
7.4
<0.05
29.1
324
324
1.0
<0.1
12.5
<20.0
<2J
525
<10J
EPA Drinking
Water Standard
1 .4 - 2.4 T
1
10
250 S
500 S
* = Average value of duplicate samples.
J = Laboratory estimated value
L = Below the requied quantitation limit.
S = Secondary standard.
T = Temperature dependent.
-------
10 feet away (screened at ± 150 feet bgs). This PCE concentration difference appears to indicate
that the fine-grained layer separating the screened zones between these two wells generally retards
downward movement of PCE at this location.
Groundwater levels, gradient, and flow direction near Halford's Cleaners all vary with
pumping at Well 11 and possibly other local wells (E & E, 1993). When Well 11 was pumping the
local groundwater flow at the site was to the northwest toward Well 11. Previous water levels have
shown that the groundwater flow direction at the site has varied from southeast to southwest to the
north by northwest. The groundwater gradient, or slope, is flat.
When the wells were sampled in August 1995, the depth to groundwater was approximately
66 feet bgs, or an elevation of 25 feet above MSL. When Well 11 was pumping, the depth to water
was approximately 70 feet bgs in May 1992 (E & E, 1993). The depth to groundwater reflects
surrounding well usage and recharge. Analysis of a pump test conducted in May 1992, indicated that
the aquifer is unconfined to semi-confined, heterogeneous, and fairly permeable (E & E 1993). Well
11 was designed to pump from this aquifer at 1,200 gpm, indicating that this aquifer is capable of
yielding significant amounts of water.
When site water levels were measured in March 1996, the depth to groundwater was
approximately 58 feet bgs, or an elevation of about 32 feet above MSL. Figure 5-4 is a map of the
piezometric groundwater surface in March 1996. At that time, groundwater flow was to the west
without any pumping from Well 11. During March 1996, the horizontal gradient was about 0.00043
feet/foot. There is an upward gradient between the deep well, MW-9, and the shallow well, MW-8,
approximately 10 feet away, of 0.01 feet/foot. This upward gradient tends to slow the downward
migration of PCE in the groundwater.
5.2 PCE Sources and Migration Pathways
PCE is the primary contaminant of concern at the Modesto site and relatively high concentra-
tions have been detected in soil, soil gas, and groundwater near Halford's Cleaners. The RI indicates
two main sources of PCE contamination that originated at Halford's Cleaners. In 1985, an old
leaking dry cleaning machine was discovered. It was then replaced with a new machine with no
leaks. Wastewater discharged from the old-style machines often contained low levels of PCE
contamination. Halford's Cleaners old machine discharged wastewater into the sewer line for many
years, and it appears that there were leaks from the sewer system. MW-8 is located near the private
sewer connection and MW-8 also had the highest levels of PCE contamination. MW-5 is located in
the vicinity of the old leaking machine and also had high levels of PCE contamination.
21
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50 100 200 300 feet
FAIRMONT AVE
SGRISWOLD AVENUE
MW-4
•
32.52
Approximate well location
Groundwater elevation in
feet above mean sea level
r
©1997 Ecology and Environment. Inc.
Figure 5-4
Groundwater Elevation - March 15, 1996
Modesto. California
ZS6IOI.O (ZIP) 07/31/97
-------
According to a 1992 Central Valley RWQCB report, (Dry Cleaners - A Major Source of PCE
in Ground Water, March 27, 1992) there are five likely mechanisms by which PCE can penetrate
sewer lines:
1. Through breaks or cracks in the sewer pipes.
2. Through pipe joints and other connections.
3. By leaching in liquid form directly through sewer lines into the vadose zone.
4. By saturating the bottom of the sewer pipe with a high concentration of PCE-
containing liquid and then PCE volatilizing from the outer edge of the pipe
into the soils.
5. By penetrating the sewer pipe as a gas.
The report states that all sewer lines leak to some extent and that mechanisms 3,4, and 5
probably occur in all piping.
Whether PCE is discharged directly to the environment or leaks from sewer lines, it
subsequently migrates downward through the unsaturated zone to the saturated zone. PCE separates
into three phases upon entering the subsurface environment: a vaporous phase which migrates
through the vadose zone; a dissolved (miscible) phase, which is entrained in groundwater and
migrates according to groundwater flow patterns; and an undissolved (immiscible) phase which sinks
through the unsaturated and saturated zones.
The undissolved, or denser-than-water nonaqueous phase liquid (DNAPL), typically travels
downward through unsaturated soils and groundwater until it encounters an impermeable soil layer
where it can accumulate and act as a long term source of contamination. DNAPL may be present,
primarily in the saturated zone. Most DNAPLs undergo limited degradation in the subsurface, and
persist for long periods while slowly releasing soluble organic constituents to groundwater through
dissolution. Even with a potentially moderate DNAPL release, which may be the case at the Modesto
Site, dissolution may continue for hundreds of years or longer under natural conditions before all the
DNAPL is dissipated and concentrations of soluble organics in groundwater return to background
levels. DNAPL can exist in the unsaturated and saturated soils as both free-phase DNAPL and
residual DNAPL. When released at the surface, free-phase DNAPL moves downward through the
soil matrix under the force of gravity or laterally along the surface of sloping stratigraphic units. As
the free-phase DNAPL moves, blobs or ganglia are trapped in pores and fractures by capillary forces.
The amount of the trapped DNAPL, known as residual saturation, is a function of the physical
properties of the DNAPL and the hydrogeologic characteristics. After the interim action, EPA will
23
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have a better idea if DNAPL is present at the site. EPA will collect additional data during this IRA
to determine if applicable aquifer remediation requirements can be met.
PCE levels in soil and groundwater are highest behind Halford's Cleaners where Halford's
private sewer line joins the sewer main lateral. Figures 5-1 and 5-2 show that elevated concentrations
(above 70 /ig/kg) of PCE in the unsaturated soils are limited to this area. The PCE concentrations in
soil samples from the deep well (MW-9), drop below 70 /ig/kg at 82 feet bgs. The fine grained units
starting at about 100 feet bgs, and the upward hydraulic gradient apparently retards downward
movement of PCE. The upward gradient between the deep well, MW-9, and the shallow well, MW-
8, approximately 10 feet away, is 0.01 feet/foot. These wells have an approximate 60 foot difference
in screened intervals. The retarded downward movement of PCE is demonstrated by the fact that the
concentration of PCE in groundwater from shallow well MW-8 (74,000 ng/L) is three orders of
magnitude greater than from MW-9 (40 /xg/L). The low relative PCE levels in the unsaturated soil,
and the high relative levels in saturated soil and groundwater indicate that most of the PCE has
reached the water table. Once PCE enters the groundwater much of it dissolves and migrates from
the source area according to the groundwater flow direction.
During the Phase 1 RI, MW-1 through MW-4 were installed, and the remaining wells were
installed during the Phase 3 RI. PCE concentrations in groundwater samples from Well 11 and the
monitoring wells are presented in Table 5-2. PCE concentrations are consistently above the MCL in
the wells closest to Halford's Cleaners (MW-3, MW-4, MW-5, MW-8, and MW-9). Table 5-2
shows that PCE levels fluctuate, which may be due to pumping rates of nearby municipal wells. At
Well 11, PCE concentrations generally decrease when the well is inactive. When Well 11 is active, it
likely draws contaminants toward it; when it is inactive, contaminants tend to be drawn in other
directions. In 1993 Well 11 was pumping and the PCE concentration was 32 jig/L. In 1995 the PCE
concentration was 0.7 /xg/L when the well was not pumping.
In summary, it appears that PCE which leaked from Halford's Cleaners and/or the sewer
leading from Halford's migrated to the groundwater. Based on the levels of dissolved PCE in
groundwater, undissolved PCE or DNAPL, may also be present. PCE-contaminated groundwater
migrated to Well 11, although levels have decreased at Well 11 since it became inactive. Based on
the levels of dissolved PCE in groundwater, undissolved PCE or DNAPL may also be present.
5.3 Groundwater Results
Figure 5-5 is a map showing the distribution and concentration of PCE in groundwater from
the most recent sampling in 1995. Similar to the PCE distribution in soil, the concentration in
groundwater is highest in wells near Halford's Cleaners (MW-3, MW-4, MW-5, and MW-8). The
24
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Table 5-2
HISTORICAL PCE CONCENTRATIONS IN GROUNDWATER
PHASE mRI
WeU
Number
MW-1
MW-2
MW-3
MW-4
MW-5
MW-6
MW-7
MW-8
MW-9
WeU 11
PCE Og/L)
March 1992
71
47
900
2.800
—
-
—
-
—
7
November 1993
340
51
4,200
1.500
-
-
-
-
—
32
August 1995
145.5
171.8
2.706
904
17,300
44
4.2
74,000
40
0.7
- = Well was not installed until 1995.
Well 11 was taken out of active use in October, 1994.
25
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MENSINGER AVENUE
GEER AVE.
*
*"g-
MW-6
44.0 X
X
y
.-'< y
— / ...
/
s
s
s
s
s
X"
u
OX 1
GROVE
r
50 100
200
300 feet
MW-6
•
44.0-
PCE concentration in groundwater
* Well MW-9 was screened at a deeper level
than surrounding wells and was not used in
preparing this map. The PCE concentration
in MW-9 was 40 ng/1-
©1997 Ecology and Environment. Inc.
ZS6IOI.f (ZIP) 07/31/97
Figure 5-5
PCE Concentrations in Groundwater (August 1995)
-------
federal and state MCLs for PCE in drinking water is 5.0 /ig/L. The MCL was exceeded in all wells
except MW-7, and the highest concentration of PCE was 74,000 /ig/L in MW-8 near Halford's
Cleaners sewer connection to the main line. The other shallow groundwater sample near Halford's
Cleaners (MW-5) indicated 17,300 /ig/L PCE. MW-7, which was placed upgradient of Halford's
Cleaners, indicated the lowest PCE concentration of 4.2 /ig/L; based on this low relative concentra-
tion, an upgradient source of contamination appears unlikely. MW-6, which was placed down-
gradient of Halford's Cleaners to help define the lateral extent of contamination, indicated 44.0 /tg/L
of PCE. In summary, PCE was found at high levels near Halford's Cleaners and decreases as a
function of distance away from Halford's.
Toluene was found at MW-8 at 13,200 /ig/L; the State MCL for toluene is 150 /ig/L. Since
toluene is not a breakdown product of PCE and is not typically associated with the PCE manufactur-
ing process, the presence of toluene may indicate a separate source of contamination. Toluene was
not detected at other wells near Halford's Cleaners. Low levels were detected at MW-6 (8.2 /ig/L)
and MW-7 (4.0 /ig/L). Other volatile organic analytes were acetone, chloroform, and chloromethane.
Of these, chloroform was found at MW-7 at 1.6 /ig/L (MCL = 100 /tg/L), and acetone (3/tg/L),
chloroform (0.4 /ig/L) and chloromethane (0.3 /ig/L) were found at Well 11. Phase 1 RI groundwa-
ter samples were also analyzed for cis-1,2 DCE; 1,1,1-TCA; benzene; ethylbenzene; and xylene.
These analyses were not conducted during the Phase 3 RI because of the low levels found during the
Phase 1 RI.
Chloroform was found at MW-7 at 1.6 /ig/L, below the MCL of 100 /ig/L, and low levels of
acetone (3 ng/L), chloroform (0.4 /ig/L), and chloromethane (0.3 /ig/L) were found at Well 11.
Acetone and chloroform are common laboratory contaminants.
Metals in groundwater were below drinking water standards except for manganese. The
secondary MCL for manganese was exceeded in unfiltered samples from MW-3, 5 and 7. Drinking
water standards were exceeded for nitrate at MW-1, 2, 3, 5, 7, and 8, and for Total Dissolved Solids
(TDS) at MW-1, 2, 3, 5, 6, 7, and Municipal Well 11. Since these data show no apparent correla-
tion to PCE contamination (i.e., are not site related) they will not be addressed in the remedy.
However, EPA will meet permit discharge requirements during the IRA with respect to manganese
and nitrate, and the Agency will collect additional data to determine if these concentrations represent
background levels.
Based on available data, PCE-contaminated groundwater is migrating away from Halford's
Cleaners and could impact future drinking water wells in the event drinking water wells were installed
within the plume. Under a worst-case scenario, PCE migration could impact additional municipal
drinking water wells (other than Well 11).
27
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5.4 Soil Results
Figure 5-6 is a map showing the aerial distribution of PCE concentrations from the Phase 3
RI in (unsaturated) soil above, and (saturated) soil below the water table (also see cross sections,
Figures 5-1 and 5-2). Elevated concentrations of PCE in the unsaturated soils were only found in
samples from MW-5 and MW-9. The highest PCE concentration in unsaturated soil was 248.4 jtg/kg
at 31.5 feet bgs in boring MW-5, near the former location of the leaking dry cleaning machine.
Samples from other borings in the immediate vicinity of Halford's Cleaners (MW-8, MW-9, and
SV-1) also indicated detectable levels of PCE in the unsaturated zone. Samples from outlying borings
(MW-6 and MW-7) indicated no detectable levels of PCE in the unsaturated zone.
Elevated PCE concentrations in saturated soils were found in samples from MW-3, MW-4,
MW-5 and MW-9. The highest PCE concentration found in saturated soil was 555 /xg/kg at 67.5 feet
bgs in boring MW-8, near Halford's Cleaners sewer connection to the main line. Detectable levels of
PCE were found in saturated soil samples from all other borings, although the outlying borings again
indicated the lowest levels. Maximum PCE levels in saturated soil from the two outlying borings
were 32.7 pg/kg at MW-6 (90 feet bgs) and 4.8 Mg/kg at MW-7 (90 feet bgs).
Headspace vapor analyses during the Phase 3 RI indicated PCE concentrations up to 2,300
Mg/kg (MW-5 at 24 feet and 66 feet bgs) and also generally increased closer to the water table.
Consistent with soil and groundwater data, soil headspace data demonstrated the highest PCE
concentrations near Halford's Cleaners (MW-5, MW-8, MW-9, SV-1) and lower concentrations at the
outlying wells (MW-6, MW-7). The highest PCE concentration at MW-6 was 23 jig/kg at 85 feet
bgs and MW-7 had no detectable levels of PCE.
In summary, the highest levels of PCE in soil were found closest to Halford's Cleaners, and
levels in saturated soil are higher than those in unsaturated soils.
5.5 Soil Gas Results
1995 soil gas data are presented in Table 5-3. PCE was present in each soil gas sample and
concentrations ranged from 200.0 pg/L in SV2-C (32 to 34 feet bgs) to 1591.7 /xg/L in SV1-A (50-55
feet bgs). Soil gas sampling during the Phase 1 and Phase 2 RIs consisted of shallow sampling
(between 3 and 20 feet bgs) near Halford's Cleaners, and along the sewer line downstream of the
Halford's Cleaners sewer connection. These data indicated high relative PCE concentrations near
Halford's Cleaners and the sewer and decreasing concentrations away from these areas.
Since the highest PCE levels were found closest to the water table, there may be a net
migration (off gassing) of PCE from the groundwater to the soil vadose zone. Therefore, to the
extent that the groundwater plume migrates, soil vapor contamination may also migrate. If DNAPL
28
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-------
is present, it would act as a more concentrated and permanent source of PCE for off gassing and PCE
migration through ground water.
Table 5-3
SUMMARY OF SOIL GAS ANALYTICAL DATA
PHASE m RI
Monitoring
Well
SV2-B
SV2-C
SV-1 A
SV-1 B
SV-1 C
Screen Interval
(feet/bgs)
50-52
32-34
50-55
30-32
23 -25
PCE
0
-------
trapped in the subsurface can act as a continuing source of dissolved contaminants to groundwater,
inhibiting the restoration of the aquifer.
EPA will collect additional data during this IRA to determine if the applicable aquifer cleanup
requirements can be met.
5.7 Radionuclides
Naturally occurring uranium is present throughout the Central Valley. Sedimentary layers
beneath Modesto were deposited approximately 10,000 years ago, when glaciers eroded granitic rocks
in the Sierra Nevada mountains. The crystalline structure of granitic rocks naturally contain small
amounts of uranium which eventually become dissolved in the groundwater.
In addition to uranium, RI groundwater analyses also included gross alpha and beta levels,
radon 222, and radium 226 and 228. Gross alpha and beta levels were obtained to determine the
overall extent of radioactivity in groundwater and will be used in estimating radionuclide loading on
future treatment systems. Radon 222, radium 226 and radium 228 levels were obtained because these
compounds are breakdown or daughter products of uranium 238.
Radionuclide analyses were conducted for groundwater samples only. Radionuclides in soil
are less significant than in groundwater for assessing risk and determining remedial options because
there is no current exposure pathway for radionuclides in soil; the site area is paved and any uranium
in the soil would not be mobile. However groundwater consumption could be an exposure pathway if
drinking water wells were installed at the site or, potentially, if Well 11 were put back in use.
Radionuclide data and corresponding MCLs are presented in Table 5-4. In general, radionuclide
levels were highest at MW-6 and MW-7 (see Figure 1-2). These wells are the furthest south and
furthest north, respectively, from Halford's Cleaners. In general, radionuclides in the groundwater
were not found at concentrations above MCLs, with the exception of gross alpha levels which were
exceeded at all locations but MW-9. The MCL for uranium was also exceeded at MW-4, MW-6 and
MW-7.
SECTION 6 SUMMARY OF SITE RISKS
6.1 Risk Assessment
In 1994, EPA conducted a baseline human health risk assessment which was revised and
updated in 1997 to incorporate the Phase 3 RI data. The risk assessment evaluated residential
groundwater ingestion and inhalation of indoor air exposure pathways. Current and future land and
groundwater use scenarios were evaluated using soil gas and groundwater data collected during the RI
31
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Table 5-4
SUMMARY OF RADIONUCLIDES IN GROUNDWATER SAMPLES
PHASE III RI
Well
Number
MW-1
MW-2
MW-3
MW-4
MW-5
MW-6
MW-7
MW-8
MW-9
Well 1 1
Gross Alpha
(pCi/L)
19 ± 2.8
18 ± 2.3
26 ± 2.6
10 ± 1.7
24 ±2.8
70 ± 4.9
52 ± 4.7
21 ± 1.8
7.8 ± 1.1
24 ± 2.0
Gross Beta
(pCi/L)
12 ± 2.4
14 ± 2.0
18 ± 2.1
12 ± 1.6
13 ± 2.7
37 ± 3.5
24 ± 3.5
19 ± 1.9
4.8 ± 1.3
16 ± 1.9
Radium-226DA
(pCi/L)
<0.20
0.31 ±0.11
0.19 ± 0.069
0.22 ± 0.077
0.42 ±0.11
0.24 ± 0.094
0.15 ± 0.071
<0.22
<0.20
<0.18
Radium-228
(pCi/L)
<0.66
<0.78
<0.77
<0.80
0.75 ± 0.39
0.96 ± 0.48
1.1 ± 0.45
0.89 ± 0.44
1.0 ± 0.45
<0.79
Uranium-234
(pO/L)
14 ± 1.7
17 ± 1.2
6.2 ± 1.0
20 ± 1.5
19 ± 1.5
40 ± 1.8
31 ± 2.4
18 ± 1.4
6.7 ± 0.81
15 ± 1.1
Uranium-235
(pCi/L)
<0.35
0.69 ± 0.25
0.21 ± 0.19
0.47 ± 0.23
0.81 ± 0.32
1.3 ± 0.33
2.1 ± 0.63
0.54 ± 0.25
0.31± 0.17
0.40 ± 0.18
Uranium-238DA
(pCi/L)
12 ± 1.6
12 ± 1.0
5.3 ± 0.95
15 ± 1.3
15 ± 1.3
32 ± 1.6
30 ± 2.4
14 ± 1.3
3.9 ± 0.62
12 ± 0.98
Radon-222
(pCi/L)
<100
<100
250 ± 17
1,700 ± 38
910 ± 28
1,100 ± 30
850 ± 27
1,200 ± 32
200 ± 16
490 ± 21
Drinking Water Standards:
Constituent
Gross Alpha
Gross Beta1
Uranium1
Total Radium (226+228)
Radium 226
Primary MCL (pCi/L)
15
50
20
5
3
The result is in boldface if the MCL is exceeded.
1 State of California MCL.
-------
for PCE and other VOCs. The inhalation of volatile chemicals released during routine household
water use (e.g., showering and dish washing) also was evaluated. For the current land use scenarios,
risks were estimated for exposure to indoor vapors based on modeling of soil gas concentrations. The
future land use scenario assumed ingestion of untreated site groundwater from a "hot spot" near
Halford's Cleaners. Average and reasonable maximum exposure (RMEs) were calculated to assess
carcinogenic and noncarcinogenic risks.
In conducting the risk assessment, conservative upper-bound exposure values developed by
EPA were used to calculate the "theoretical excess cancer risk." The theoretical excess cancer risk is
an estimation of the probability of developing cancer over and above the normal background incidence
of cancer. A number of assumptions were made in the risk assessment that were designed to err on
the side of health protection in order to avoid underestimating the risk to the public. Moreover, the
chemical concentrations used to estimate the increased individual carcinogenic risk assumed that
continuous exposure occurs over a 30-year period; therefore, the actual probability of cancer is likely
to be much lower than the estimates and may even be as low as zero (EPA 1989a).
EPA has adopted the policy that acceptable exposures to known or suspected carcinogens fall
within an excess upper-bound lifetime cancer risk of between one in 10,000 (10"*) and one in a
million (lO^5) (EPA 1991a). For noncarcinogens, a hazard index of 1 or less is recognized as the
level at which no adverse health effects would be expected.
As shown in Table 6-1, current and future carcinogenic risks for inhalation of soil gas for
indoor air range from 9 x 10'7 (9 in ten million) to 9 x 10"6 (9 in one million) while the hazard indices
range from 0.1 to 0.5. Under future land use conditions, carcinogenic risks from ingestion and
inhalation of contamination range from 1 x 10'2 (1 in 100) to 5 x 10'2 (1 in 500) while the hazard
indices range from 100 to 400. The ingestion of untreated groundwater at the hot spot and inhalation
pathways contribute the greatest risk.
Inhalation risks associated with current land use scenarios were generally within acceptable
risk levels; however, the risks associated with a future exposure scenario, which assumed consump-
tion of untreated site groundwater at the hot spot (i.e., MW-8), were above the currently acceptable
risk standards (EPA 199la) and levels exceeded drinking water MCLs.
In summary, the risk assessment found the current risk levels are within EPA's acceptable
levels; however, for the hypothetical future scenario in which an individual ingests untreated
groundwater directly from the hot spot, the risks were found to be outside EPA's acceptable levels,
warranting site remediation. If not treated, contaminants may continue to migrate from the source
33
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Table 6-1
SUMMARY OF ESTIMATED RISK VALUES
BASELINE HUMAN HEALTH RISK ASSESSMENT
MODESTO GROUND WATER CONTAMINATION SITE
Pathway
Hazard Index
RME
Hazard Index
Average
Cancer Risk
RME
Cancer Risk
Average
^^K^^m^: '*/& K^W^ilH-^ ^-'" 'v;> V'X ^'>>~$ '*
Indoor Air:
Inhalation of Soil Gas
Total Risk
0.5
0.5
0.1
0.1
9x 10-6
9x10-*
9 x 1C'7
9xlO-7
4p^$j$!$$3^^ , -f <
Indoor Air:
Inhalation of Soil Gas
Drinking Water:
Digestion and Inhalation
Total Risk
0.5
400
400
0.1
100
100
9x 10-6
5 x 10-1
5xlO-J
9 x 1C'7
1 x lO'2
1 xlO"2
RME = Reasonable Maximum Exposure
Average = Average of typical exposure parameters
34
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area and may potentially impact operating municipal wells throughout the City. As many as 150,000
residents could be affected.
Although, as Table 6-1 shows, inhalation of soil gas for current and future land use scenarios
are below acceptable risk levels, SVE will assist the groundwater remediation effort.
EPA also considered potential ecological risks and determined that there was no unacceptable
risk because there is no exposure pathway.
6.2 Rationale for the Limited Scope of the Action
An interim, rather than final, ROD was developed because of uncertainties over whether any
available remedial approach is capable of achieving groundwater standards throughout the plume, and
the necessity of further delineating the downgradient edge of the plume. The interim action will
significantly control the source of contamination by removing and hydraulically containing contami-
nants in the source area.
This IRA includes directly treating the groundwater by air stripping and SVE to remove the
PCE from pore spaces in the soil zone directly above the water table. Although this action is limited
in scope, it is expected to remove 90-to-95 percent of the dissolved PCE from groundwater. It is
significantly more cost effective than other alternatives because it will generate less treated water to
be discharged and also avoids unnecessary negative impacts to the community.
As previously discussed, EPA performed a human health risk assessment to evaluate the risks
associated with PCE and other volatile organic chemicals in the groundwater and soil gas. EPA's risk
assessment found that current risk levels for soil and groundwater do not exceed EPA standards.
Unacceptable risks, however, are predicted in a hypothetical future scenario in which an individual
ingests untreated groundwater from the area of highest contamination near Halford's Cleaners. If not
treated, contaminants may continue to migrate from the source area and may potentially impact
operating municipal wells throughout the city. Removal of contaminants during the IRA will decrease
potential threats to human health and the environment while the final remedial action is being
developed.
Furthermore, this aquifer is considered viable for use in the event that additional wells are
installed in the affected parts of the aquifer. EPA expects to return usable groundwater to their
beneficial use wherever practicable, within a timeframe that is reasonable given the particular
circumstances of the site. When restoration of groundwater to beneficial uses is not practicable, EPA
expects to eliminate the highest contaminant levels at the source (source control), prevent further
migration of the plume, prevent exposure to the contaminated groundwater, and evaluate further risk
reduction.
35
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6.3 Risks of an Interim Action
This section evaluates the risk associated with EPA's preferred remedy. Volatile contami-
nants would be removed from the subsurface through extraction followed by treatment by air stripping
and by SVE. Generated vapors from the air stripper and SVE system would be captured by activated
carbon, which would prevent possible exposures to the surrounding community. Little or no hazards
to workers would be expected during remedy installation. Standard personal protection practices
would protect workers from potential exposures.
SECTION 7 DESCRIPTION OF ALTERNATIVES
This section describes the alternative remedies and technologies for the site that EPA has-
evaluated.
7.1 The Selection of Treatment Technologies and Development of Alternatives
Contamination at the Modesto Ground Water Contamination Site consists primarily of PCE.
Contamination is present in both the vadose zone of the soil and, to a much greater extent, in
groundwater. DNAPL is also suspected to be present, primarily in the saturated zone. Considerable
experience exists for addressing sites with this type of contamination. EPA has developed the
presumptive remedy program in an effort to use prior experience to streamline the selection of
remedial technologies for Superfund sites.
EPA had previously considered a remedial alternative that used well-head treatment of water
collected as part of the City of Modesto's existing water-extraction program. However, because the
city's municipal wells may not always be operating (for example, Well 11 has been shut down due to
naturally occurring uranium), this approach cannot be relied on for continuous treatment. Therefore,
well head treatment cannot be relied on to ensure source control.
7.2 Groundwater
This section evaluates technologies for remediation of groundwater contamination. OSWER
Directive 9283.1-12 iterates the general objectives of a groundwater remedial program as follows:
• Prevent exposure to contaminated groundwater above acceptable risk levels;
• Prevent or minimize further migration of the contaminant plume (plume
contaminant);
• Prevent or minimize further migration of contaminants from source materials
to groundwater (source control); and
36
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• Return groundwaters to beneficial uses whenever practicable.
This guidance establishes presumptive technologies and remedies applicable to groundwater
contamination sites, as discussed below. Three types of in situ treatment can be performed:
biological, chemical, and physical. Evaluations of each are discussed below.
Biological
PCE is difficult, though not impossible, to degrade biologically. PCE and other chlorinated
solvents have been found to degrade naturally in the subsurface through anaerobic reductive
dechlorination. This process occurs naturally, but can be accelerated by the addition of nutrients such
as nitrates and phosphates. Considerable research has been conducted on the aerobic degradation of
chlorinated solvents, as aerobic processes are much faster than anaerobic processes. However, the
successful implementations to date require the addition of organic cosubstrates that act as electron
donors. Most research has focused on the use of methanol as the preferred electron donor. Other
cosubstrates, including some aromatic hydrocarbons, have been evaluated in studies of other
chlorinated solvents. One aromatic hydrocarbon, toluene, is present in the groundwater at some
locations, most notably at MW-8 during the Phase 3 RI, where it was detected at 13,200 fig/L. This
sample location also exhibited the highest detected PCE concentration of 74,000 ng/L. However,
toluene is generally present throughout the aquifer at levels too low (< 10 jig/L) to be useful as a
biotreatment cosubstrate. Addition of inorganic nutrients to accelerate either anaerobic or aerobic
biodegradation, or addition of organic cosubstrates would not be acceptable since the aquifer is used
directly as a drinking water source (although there are no known drinking water wells within the
contaminant plume). Due to these implementability considerations, in situ biotreatment is not
considered appropriate for this site.
Chemical
Chemical in situ treatment of chlorinated organics has received more attention lately with the
development of treatment systems using zero-valent iron to dechlorinate these compounds to ethane
and chloride. However, this technology would not be applicable to this site. This technology
requires a stable and consistent groundwater flow pattern. This is required so that the permeable
treatment beds containing the iron filings can predictably intercept the groundwater plume and thus
treat the contamination. Because of changing groundwater pumping patterns in response to municipal
water supply needs, the subsurface flow patterns may vary considerably, making it difficult to
correctly place the permeable treatment beds. Furthermore, this technology benefits greatly from
37
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having an impermeable layer to act as a lower barrier to the groundwater flow. This is necessary to
prevent groundwater from simply flowing under the treatment beds. At the Modesto Ground Water
Contamination Site, no subsurface barriers exist close enough to the surface to adequately contain the
lower portion of the plume. For these reasons, in situ chemical treatment is not considered for this
site.
Physical
Physical in situ treatment involves the removal, not destruction, of contaminants from the
groundwater. The only way to physically remove the dissolved PCE is as a vapor. This would be
accomplished through sparging air into the aquifer to strip the PCE from the groundwater. The
resultant vapors, now present in the vadose zone, would have to be collected with an SVE system.
This approach is integrated into two of the remedial alternatives.
Ex situ Treatment
Ex situ treatments for groundwater require collection of the groundwater with wells or
collection trenches, followed by above-ground treatment. The extracted groundwater will be pumped
to a treatment facility that would be located in the open area behind Halford's Cleaners, or nearby.
Groundwater treatment will be by air stripping, the preferred technology for this site. Other
groundwater treatment technologies evaluated were carbon adsorption and UV/oxidation. Under the
.EPA Presumptive Remedy Guidance, air stripping, carbon adsorption and UV/oxidation are all
presumptive technologies for ex situ groundwater treatment for VOCs. Air stripping was selected
because it is the most cost effective. Air stripping can be accomplished either through a packed
tower, or through lower profile tray strippers. Either technique will produce effluent concentrations
at or below required discharge permit requirements. Aqueous-phase carbon adsorption will not be
required to "polish" the effluent to meet cleanup standards. However, carbon could be used to guard
against untreated groundwater passing through the system during process upsets. Such events could
also be avoided with proper operational controls and interlocks. The need for carbon will be
determined in the design phase after final arrangements have been made for treated groundwater
discharge. Vapor-phase carbon will be used in this alternative to treat off gas from the air stripper.
This carbon will remove organic compounds from the off gas.
Treated Groundwater Disposal
The site is located in an urban area, which limits the options for discharge. There are no
available surface waterbodies located near the site. Thus, disposal options are limited to:
38
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• Discharge to the vadose zone;
• Reinjection to ground water;
• Discharge to the City of Modesto drinking water supply system; and
• Discharge to the City of Modesto sewer system.
Because of planned SVE treatment of soil in the vadose zone, discharge to the vadose zone
would not be preferred. Discharge to the vadose zone would interfere with extraction of vapors by
saturating the soil and disrupt soil gas flow patterns.
Furthermore, reinjection to groundwater would be difficult and expensive to implement.
Treated groundwater would be reinjected beyond the area from which extraction is taking place. This
is required to prevent dilution of extracted groundwater (limiting the efficiency of the remedial
program), and to make sure that reinjected groundwater does not cause further migration of the plume
away from its current extent or from the extraction program. Such a reinjection program would
require the pumping of treated groundwater for several city blocks, increasing the cost of the remedial
program. Since the surrounding area is a heavily developed residential and commercial area, the
reinjection may have to be performed on private property or adjacent to private property used as a
residence or business. This may be difficult to implement. Reinjection can also be expensive due to
the pressure needed to inject the water and the added maintenance required to keep the injection well
free from clogs that can inhibit reinjection.
It is technically possible to treat the extracted groundwater and discharge it the drinking water
system. When Well 11 was operating during the early 1990's with granular activated carbon
treatment of the extracted groundwater prior to distribution, treated groundwater was in fact being
discharged to the drinking water system. However, it is expected to be more difficult to implement
the discharge of treated groundwater to be extracted from the most contaminated portions of aquifer.
To discharge to the City of Modesto sewer system, a permit application must be submitted to
and approved by the City of Modesto. If approved, the permit will specify the degree of treatment
required for the contaminants of concern and possibly for naturally occurring compounds or elements
as well. Based on preliminary discussions with the City of Modesto, PCE would be required to be
treated to the detection limit of no higher than 5 /ig/L prior to discharge. Other requirements may be
imposed by the discharge permit, and will have to be met by the treatment system prior to discharge.
This disposal option appears to be the most implementable and cost-effective disposal option.
However, final determination of treated groundwater disposal will depend on agreement on discharge
permit requirements.
39
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If treated groundwater is discharged to the sewer system, a connection will be made to the
sewer line located behind Halford's Cleaners, which is located less than 100 feet from where
treatment would likely take place. This sewer line will be able to accommodate the complete 50 gpm
flow rate estimated to be needed to remediate the site.
The presence of naturally occurring uranium in the groundwater may complicate treated
groundwater disposal options. Groundwater that has been treated to remove organic contaminants
may require additional treatment to remove radionuclides prior to disposal. Although these naturally
occurring elements cannot be considered contaminants, their removal by ion exchange may be
required to comply with the permits issued to allow treated groundwater discharge.
The ion exchange treatment system would use ion exchange columns, packed with anion
exchange resin, in series to remove the uranium oxide/carbonate complexes from the groundwater.
Resin usage rates were conservatively estimated assuming uranium was encountered at the higher
concentrations seen in MW-6 and MW-7 at the farther edges of the plume. Spent resin would be
disposed of rather than regenerated because regeneration would produce a liquid radioactive waste
that would only have to be resolidified before disposal. Although this removal technique is easy and
straightforward to implement, several options exist for disposal of the spent resin, and these can vary
considerably in cost. Until the process is implemented, it is difficult to predict which of these
approaches would be used, as such disposal arrangements are done on a case-by-case basis. The
options for disposal of the resins include disposal in a low-level radioactive waste (LLRW) facility,
or, as presented in the EPA guidance document Suggested Guidelines for Disposal of Drinking Water
Treatment Wastes Containing Radioactivity (June 1994), in a RCRA hazardous waste facility.
Commitments by disposal facilities on acceptability and costs of disposal can only be made as EPA
prepares to actually dispose of these materials.
For costing purposes, it was assumed that spent resins would be disposed of at a LLRW
facility. A number of avenues were explored for disposing of the spent resins. Disposing of the
spent resins involves removal of the resins from the ion exchange tanks, performing any pretreatment
that might be required (such as dewatering), transportation, and disposal.
7.3 Soils
This section evaluates technologies for remediation of soil vapor contamination. For soils
contaminated with VOCs, the EPA has identified SVE as the primary presumptive remedy (EPA,
1993). The Modesto Ground Water Contamination Site is well suited for SVE for the following
reasons:
40
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• The vadose zone soils contain significant amounts of sandy materials which
has a fairly high vapor transmissivity and would facilitate contaminant
removal. Interspersed in the sandy materials are zones and lenses of less
permeable clayey and silty soils. While these zones may limit the effective-
ness of SVE, proper design of the system can take these into account to
achieve effective removal. Much of the soil gas contamination may emanate
from sources in the saturated zone. By screening some SVE wells near the
water table, the potential impacts of these levels may be avoided. Halford's
Cleaners, the principal source of the contamination, operated an SVE system
in the early 1990s, and this system was successful in removing some PCE
contamination. The success of this operation indicates that operation of a
larger program to capture more of the PCE contamination would be effec-
tive. Removal of soil gas from near the water table should also accelerate
the rate of groundwater remediation.
• The area of the PCE release is urban. Soil excavation would be difficult and
implementation would be disruptive to the surrounding area. Thus, in situ
approaches such as SVE are preferred.
• Contamination is generally limited to PCE (some toluene was also found at
significant-concentrations in one sample). Nonvolatile compounds, which
would not respond to this type of treatment, are not present.
For these reasons, SVE will be the only technology considered for remediation of the soils.
In four of the six action alternatives developed below, SVE is incorporated in two ways. The first is
as a principal stand-alone soil vapor treatment technology, and second as a complementary component
of an air-sparging groundwater treatment approach. In either case, the SVE system would extract
contaminated soil vapor from the vadose zone. In the second case, migration of PCE vapor from the
groundwater would be enhanced through air sparging. Extracted soil vapor would be treated using
vapor phase GAC.
7.4 Assembly of Alternatives
The soil and groundwater treatments identified above as being appropriate for this site (SVE
for soil, and extraction and treatment for groundwater) are combined below to create six action-
oriented remedial alternatives for this site. Alternatives 1 and 4 are the basis for the two alternatives
that follow them. Alternatives 2 and 5 add SVE to the groundwater extraction and treatment
programs in 1 and 4. Likewise, Alternatives 3 and 6 add air sparging. Together with the no action
alternative, the six remedial alternatives for the IRA for the Modesto Ground Water Contamination
Site are:
• Alternative 1: Groundwater Extraction and Treatment (4 Extraction Wells);
Monitoring and Evaluation of Downgradient Edges of the Plume;
41
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• Alternative 2: SVE and Groundwater Extraction and Treatment (4 Extraction
Wells); Monitoring and Evaluation of Downgradient Edges of the Plume;
• Alternative 3: Air Sparging, SVE, and Groundwater Extraction and Treat-
ment (4 Extraction Wells); Monitoring and Evaluation of Downgradient
Edges of the Plume;
• Alternative 4: Groundwater Extraction and Treatment of Main Source Area
(1 Extraction Well); Monitoring and Evaluation of Downgradient Edges of
the Plume;
• Alternative 5: SVE and Groundwater Extraction and Treatment of Main
Source Area (1 Extraction Well); Monitoring and Evaluation of Down-
gradient Edges of the Plume; and
• Alternative 6: Air Sparging, SVE, and Groundwater Extraction and Treat-
ment of Main Source Area (1 Extraction Well); Monitoring and Evaluation
of Downgradient Edges of the Plume.
• Alternative 7: No Action
Each of these alternatives is described briefly below. These descriptions are provided to
present the main components of each alternative, including treatment, containment, and general
components. Component costs are addressed in Table 9-1. Each action alternative also includes the
following institutional controls: signing and fencing around the treatment area. These institutional
controls would be maintained for the duration of treatment. The need for additional institutional
controls will be evaluated in the final remedy. In addition, during the RD phase for each action
alternative, the downgradient edges of the plume will be delineated.
7.4.1 Alternative 1: Groundwater Extraction and Treatment (4 Extraction Wells); Monitoring
and Evaluation of Downgradient Edges of the Plume
This alternative performs direct remedial action only on the groundwater medium. This
alternative calls for extraction of groundwater from portions of the aquifer exceeding 5 jtg/L PCE.
To implement this alternative, additional monitoring wells would be required to better define this
extent of contamination.
Groundwater extraction rates and screened intervals can be evaluated by considering site
stratigraphy and vertical contaminant distribution. The potential extraction rates evaluated were
selected assuming extraction wells screened over a 40-foot interval (roughly 65 to 105 feet bgs).
Contamination has been detected above 5 /*g/L at depths greater than 105 feet bgs at the site. For
example, MW-9, installed near the apparent source area behind Halford's Cleaners, was screened at a
42
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depth interval of 144-154 feet bgs, and was found to contain 40 /xg/L of PCE. However, this level is
significantly lower than adjacent wells screened at higher elevations (e.g., MW-8, located next to
MW-9 but screened from 60 to 90 feet, with a PCE concentration of 74,000 ng/L). A layer of finer-
grained sediments located below approximately 100 feet bgs appears to significantly limit the
downward migration of contaminants. It is believed that this layer provides a significant barrier to
contaminant migration, both as dissolved species and as a DNAPL, limiting the amount of contamina-
tion that would be present in the deeper regions. Thus groundwater removal would focus on the
upper part of the saturated zone.
Although modeling conducted for the Feasibility Study cannot take the potential variations in
regional flow patterns into account, the results from this model can be used to estimate the pumping
requirements for remediating the groundwater plume. The modeling results show pumping a single
well at 30 gpm within a year captures groundwater within about 18,500 yd2 (3.8 acres), and a single
well pumping at 60 gpm within a year captures groundwater within about 38,400 yd2 (8 acres). The
size of the plume, as defined by the estimated 5 pg/L PCE concentration contour, is difficult to
estimate using the nine wells at the site, one of which is a deep well not monitoring the zone of
highest contamination. Figure 5-5 presents estimated groundwater concentration contours to 10 ppb
based on August 1995 sampling data. The plume delineated by these contours is assumed to stretch
northwest toward the Well 11, since PCE contamination has been detected there. However, no other
wells are present in that direction between Well 11 and MW-2.
Contamination in Well 11 was first detected in 1984. By 1987, continued monitoring showed
that no PCE was present. However, PCE was again detected two years later in 1989. Once the City
of Modesto added activated carbon treatment, Well 11 was brought back into service in 1991. It was
shut down again in 1995 due to the presence of naturally occurring uranium. Previous shutdowns of
this well described above indicate that, while it is apparent that Well 11 draws contaminants from the
Halford's Cleaners location towards the well, this migration pattern diminishes or stops upon
cessation of pumping at the well. This is demonstrated by the lack of contamination present in 1987
after a few years of no pumping. As Well 11 has been out of service since 1995, the effects of Well
11 on the shape of the plume, including its downgradient edges, will be minimal by the time a
groundwater IRA remedial program is instituted at the site. Thus, for the purpose of estimating the
requirements of a groundwater IRA, it is assumed that the plume will not extend significantly towards
Well 11 (i.e., to the northwest). Rather, the extent of the plume will be limited to about 400 feet to
the northwest of the source area—about the same as is estimated for the northeast and southwest
directions (the southwest component of the plume is estimated to be larger, as demonstrated by the
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higher PCE level of 44 /*g/L in MW-6). Based on this analysis, the area of the plume is estimated to
be about 86,000 yd2 (18 acres).
Since the areal extent of the plume is estimated to be about 86,000 yd2 and a 30 gpm well
would capture an estimated 18,500 yd2, and a 60 gpm well 38,400 yd2, a total of about 130 to 140
total gpm of groundwater needs to be extracted to fully address the estimated extent of the groundwa-
ter plume. This alternative would require approximately 4 extraction wells. The exact number,
location, and pumping rate of the extraction wells would be determined during the IRA design phase.
During that phase, issues such as limitations on well placement from the presence of buildings and
other structures can be fully taken into account. Further delineation of the plume, including its
downgradient edges, will also be conducted at that time.
The extracted groundwater would be treated and disposed. Treatment would be by air
stripping and vapor phase GAC for the off gas from the air stripping unit. Disposal options include
reinjection to the aquifer, discharge to the sanitary sewer (leading to a publicly-owned treatment
works [POTW]), and use as drinking water (see Section 7.2). Treatment residuals (e.g., spent GAC)
would be recycled or disposed.
7.4.2 Alternative 2: SVE and Groundwater Extraction and Treatment (4 Extraction Wells);
Monitoring and Evaluation of Downgradient Edges of the Plume
This alternative incorporates all of Alternative 1, but it would also extract vapor phase PCE
from the soil and dissolved PCE from the groundwater. As described in Alternative 1, saturated-zone
PCE would be removed through groundwater extraction (potential DNAPL would have to diffuse and
dissolve into the groundwater to be removed). Vadose zone contamination (both adsorbed and free
vapor) would be removed as vapor. The area of groundwater contamination to be remediated through
this alternative is the same as estimated for Alternative 1.
The extraction of both soil vapors and groundwater can be implemented in a number of ways.
One approach is to use the same boreholes to remove both the vapor and liquid contamination, a
process called dual phase extraction. Dual phase extraction can be implemented in three ways:
• Direct suction on a well screened both above and below the water table.
This technique mainly pulls vapors from the vadose zone, but also entrains
some groundwater through the high flow rate and low pressure of the gas
and vapors drawn into the well. This would not be appropriate for this site
as most of the contamination is in the groundwater.
• Drop tube extending into the water table. This technique also relies solely
on a vacuum for removing both vapors and groundwater. However, rather
than screening a well in both zones as with the above technique, this ap-
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proach uses an unscreened well terminating with an open casing below the
water table. When a vacuum is drawn on this pipe, groundwater is removed
by suction until the groundwater table is lowered to the level of the pipe. At
that point, groundwater and vapors are alternately removed via suction. This
approach allows a certain degree of in-well air stripping to occur during
extraction. This approach is not well suited to this site because of the depth
of groundwater (greater than 60 feet). Such great depths would require too
great a vacuum to remove the water.
• Submersible pump and vacuum pump. This approach uses the same borehole
to install two separate recovery systems: slotted casing screened in the
vadose zone to collect vapors via a vacuum pump located at the surface, and
a separate screened section below the water table, where groundwater is
collected via a submersible pump. As far as general removal efficiency is
concerned, this approach would be most appropriate: the deep groundwater
would require the use of submersible pumps, while separate vapor and
groundwater removal mechanisms would allow better control of the removal
rates of these two media. However, for well location reasons discussed
below, this approach would also not be appropriate for this site.
Groundwater extraction and SVE can also be implemented in two completely separate
systems. One set of wells would be installed to remove groundwater, while a separate set of wells
would be installed for removal of soil vapor. This approach would be preferred over dual phase
extraction for the following reasons:
• The optimum locations of the SVE and groundwater extraction wells would
not be in the same place. The groundwater plume extends over 500 feet,
migrating with groundwater flows that often change direction depending on
the rate of municipal well pumping. PCE in the soil, on the other hand,
migrates downwards as a liquid, and, to a lesser extent, horizontally as a
vapor. Although vapors have traveled further laterally throughout the vadose
zone than liquid phase contamination, and have been detected in an areal
range similar to the groundwater plume, the vastly smaller mass of this
phase's contamination would make it unreasonable to collect vapor from
areas other than the primary source area, behind Halford's cleaners. It is
this area where PCE in the soil may be acting as a source of future ground-
water contamination, whereas the vapors detected farther afield may actually
be emanating from the contaminated groundwater itself.
• The vast majority of the PCE contamination is in the saturated zone.
Whereas an estimated 895 kg of PCE are present in the groundwater (not
including PCE adsorbed to soil below the groundwater table), less than 0.1
kg is estimated to be present in the vadose zone (as estimated in the Phase 3
RI), although this may underestimate the amount in the vadose zone due to
problems accurately measuring volatiles in this medium. Thus the design
and objectives of these two removal processes will be quite different in
scope, with the vapor removal component expected to be completed well
before the groundwater removal component. Keeping these two processes as
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completely separate processes will allow more flexibility in the remedial
operations.
• PCE in the vadose zone is more likely to be found in the strata of lower
permeability silty and clayey soils. To effectively remove PCE from these
zones, the vapor extraction wells would have to be screened directly in these
zones, or else the vacuum would primarily withdraw cleaner soil gas from
the more permeable sandy layers. Although placement of groundwater
extraction wells would not require quite as specific placement, it may still be
difficult to locate wells that provide optimum locations for both soil vapor
and groundwater extraction.
For these reasons, groundwater, and soil gas would be extracted for this alternative using separate
wells systems.
The groundwater extraction system would be the same as described for Alternative 1. The
SVE system would be installed to help remediate the contaminated soils in the vadose zone as well as
remove vapors emanating from the saturated zone, thus accelerating groundwater cleanup. The
lithology of the soils at the site is quite variable. Layers of highly permeable soils and low permeable
soils exist. This heterogeneity complicates the design and operation of an SVE system. The biggest
issue regarding the vadose zone at the Modesto Ground Water Contamination Site is the distribution
of contamination and the placement of extraction well screens. The migration and distribution of free
phase organics such as PCE is a complex issue controlled by a number of factors. Vapor well
screens should be placed across areas of higher PCE contamination. Based on expected vertical
migration patterns of PCE in the vadose zone, one would expect to see higher concentrations of PCE
at the base of sandy layers which are underlain by silt or clay layers (PCE accumulating on top of
low permeable layers). Furthermore, one would expect higher concentrations in silty sands or clayey
sands since this type of soil is permeable enough to allow PCE migration, but has enough organic
content to retain some of the PCE. In general, one would not expect to see very high concentrations
in the very middle of thick clay layers. The highest PCE vapors would be found near the water table,
emanating from the saturated zone.
It would not be prudent to install extraction wells that are screened across the entire vadose
zone. Only the most permeable zones or layers adjacent to a highly permeable zone would be
remediated under this scenario. A more viable approach would be to screen wells in different
lithologic sections. For example one set of wells would be screened in high permeable sands and
gravelly sands, and another set of wells would be screened in moderately permeable soils such as silty
sands. A third set of wells could be installed, if necessary, in low permeable soils such as silts and
clays. Each set of wells would be piped separately to the blower or blowers and isolated with valves.
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It is possible that one blower might be adequate; however, only one zone can be remediated at a time.
The blower would have to operate over a wide range of flows and vacuum. When the higher
permeable zones were being remediated, the blower would operate at high flows and low vacuums.
When the lower permeable zones were being remediated, the blower would operate at low flows and
high vacuums. If one blower is used, it must be able to operate at low flows without the use of an air
dilution valve.
In order to assess design requirements for the different soil types, EPA used its computer
model Hyperventilate. Since the model is geared toward petroleum contaminants, a petroleum
constituent with a vapor pressure similar to PCE was selected as the modeled contaminant. The
model output includes flow rate estimates and removal rates. The theoretical radius of influence was
estimated based on experience and calculations at other sites. Based on these data, modeling, and
experience, SVE operating parameters have been estimated for this site. These parameters are
summarized on Table 7-1. This information is developed from the limited information available from
the RI, and would need to be verified prior to a final design. The area the SVE system will draw
contaminants from will be determined through a pilot study during the design phase.
Based on data collected during the IRA, EPA will calculate the threat to groundwater from the
soil. EPA will also calculate the extent to which the SVE system accelerates groundwater cleanup.
EPA will cease SVE when the soil no longer poses a threat to groundwater and no longer accelerates
contaminant removal from groundwater.
Table 7-1
ESTIMATED SVE PARAMETERS FOR ALTERNATIVES 2 AND 5
Soil Type
Medium sand (high permeability)
Silty sand (moderately permeable)
Clayey silt (low permeability)
Screen Length
(feet)
25
20
25
flow
(scfm)
53 to 532
1 to 12
0.2 to 2
Vacuum
(inches H2O)
20
60
100
Radius of
Influence
(feet)
60
40
30
Key:
scfm = Standard cubic feet per minute.
The area that would be subject to SVE would be the main PCE source area and some of the
surrounding regions through which PCE may have migrated in the vadose zone; this is likely to
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include the area west of Halford's Cleaners, and south along the sewer line. Approximately 30 SVE
wells will be required. Treatment residuals would be managed in the same manner as for Alterna-
tive 1.
7.4.3 Alternative 3: Air Sparging, SVE, and Groundwater Extraction and Treatment (4 Ex-
traction Wells); Monitoring and Evaluation of Downgradient Edges of the Plume
This alternative is similar to Alternative 2, but includes air sparging. By injecting air into the
saturated zone, air sparging mobilizes dissolved and adsorbed PCE into vapors which can be collected
using an SVE system. This approach is analogous to in situ air stripping. The subsurface soils at
this site range from well graded sands and gravelly sands to inorganic clays. Numerous lenses of silts
and clays are also present. RI data interpretation indicates that a significant lower-permeability layer
at around 105 feet bgs has limited (but has not prevented) the migration of contaminants below this
depth. EPA has assumed that sparge wells would terminate at a depth of 105 feet bgs. The sparge
wells would have 2 to 5 feet of screen and be placed 30 to 50 feet apart (based on compilation of
literature values for sandy soils). Air would be injected at a rate of 5 to 10 scfm into each well using
either an air compressor or blower operating at 20 to 25 psig (assuming injecting air 40 feet below
water table).
The area addressed through air sparging would be larger than the area addressed by vapor
extraction alone in Alternatives 2 and 5. Since the goal of the sparging is to remove dissolved and
adsorbed contaminants from the saturated zone, the concentrations in the groundwater dictate the area
to be addressed, which is larger than the vadose zone soil or soil gas contaminated area. For the
purposes of the definition of this alternative, the area subject to air sparging is set as the entire area
described for SVE, plus any additional areas within the area of highest groundwater contamination
(roughly defined by the 1,000 ng/L PCE concentration contour in Figure 5-5) not included in this
region.
In practical terms, this means that portions of the private property lot located southwest of the
source area would have to be included in the air sparging and recovery program. Given its current
residential use, this area would not necessarily be included in the proposed SVE area because of the
probable difficulties in installing remedial facilities. However, with SVE alone, it is possible to
include a slightly smaller than optimal area in the remedial program. SVE is an inherently extractive
technology that would draw contaminants from beyond the immediate area of operation. Sparging, on
the other hand, is meant to mobilize contaminants within the saturated zone. Thus, at a minimum,
the SVE component of the sparging program must be of greater extent than the scope of the sparging
wells. This would mean a required encroachment onto the private property located immediately
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southwest of the spill area. Furthermore, while the lower viscosity and higher diffusivity of
contaminants in the soil vapor (compared to dissolved contaminants) means that areas of vadose zone
contamination not directly addressed by SVE would quickly migrate to areas where extraction is
applied; the lower viscosity, diffusivity, and potentially stronger adsorption to aquifer materials in the
saturated zone means that contaminated areas not addressed by sparging would at most be minimally
impacted by sparging operations nearby. This suggests that sparging should be applied throughout the
areas of high contamination, which includes the northeast portion of the private property.
The air sparging component of this alternative would provide for the accelerated removal of
PCE from the saturated zone. However, the air sparging activity would be focused on the area
behind Halford's Cleaners, where the principal source areas are located. As discussed for Alterna-
tive 1, the groundwater plume extends over a much larger area, up to an estimated 18 acres. To
address the groundwater contamination not impacted by the sparging, a groundwater extraction
program similar to the one described for Alternative 1 would be employed. Extraction rates and
groundwater concentrations would be similar as described for Alternative 1; however, due to the air
sparging action, the concentrations might decrease more rapidly over time.
Extracted vapor would be treated using vapor phase GAC. Treatment residuals would be
managed in the same manner as for Alternatives 1 and 2.
7.4.4 Alternative 4: Groundwater Extraction and Treatment of Main Source Area (1 Ex-
traction Well); Monitoring and Evaluation of Downgradient Edges of the Plume
This alternative is similar to Alternative 1; it uses groundwater extraction and treatment
technology to address groundwater contamination. In contrast to Alternative 1, where the groundwa-
ter extraction and treatment program would directly pump and treat contaminated groundwater from
the entire area of the plume exceeding applicable requirements (except for that portion located below
the low permeability layer noted starting at about 100 feet bgs, as discussed in Section 7.4.1),
Alternative 4 focuses on extracting and treating the more highly contaminated groundwater located
near the source of contamination behind Halford's Cleaners. By focusing remedial actions on this
most contaminated groundwater, the rate of PCE removal (in pounds per day) would be almost as
great as would be realized with Alternative 1, yet substantially less groundwater would have to be
extracted, treated, and disposed of. This approach would remove the highest levels of contamination
at the source area (source control). Operation of the extraction well would hydraulically isolate the
surrounding aquifer. Meanwhile, the areas serving as continuing sources of groundwater contamina-
tion would be hydraulically isolated from the surrounding aquifer. With isolation of the source of
contamination, the lower concentration fringes of the plume would be expected to dissipate through
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natural alternative processes. Monitoring of these outlying areas would be incorporated to ensure that
concentrations decrease upon source area containment and additional remediation of these outlying
areas, if necessary, will be addressed in the final ROD.
Based on the estimated capture zones, pumping at a rate of only 50 gpm would be sufficient
to capture an area of around 250 to 300 feet, which would address an area encompassing 90-to-95
percent of the mass of PCE in ground water. For reference, this area roughly corresponds to the area
defined by the 1,000 /tg/L contour (see Figure 5-5). This zone would more than include the
suspected sources of continuing groundwater contamination, based on what is known of the releases
from Halford's Cleaners and the nearby sewer. One or more extraction wells are anticipated for this
alternative; the exact number and location of the extraction wells would be determined during the
design phase. Treatment residuals would be managed in the same manner as for Alternatives 1 and 3;
however, the amount of treated groundwater and thus the associated cost of disposal would be
significantly less for this alternative.
During the IRA, operation of the extraction well will draw groundwater in the most
contaminated, source-area portions of the plume to the well, thus inhibiting downgradient migration of
those source-area contaminants.
7.4.5 Alternative 5: SVE and Groundwater Extraction and Treatment of Main Source Area (1
Extraction Well); Monitoring and Evaluation of Downgradient Edges of the Plume
This alternative is nearly identical to Alternative 4; however, in addition to groundwater
extraction and treatment (source control), SVE treatment of the soil would be performed. The area of
groundwater contamination to be remediated through this alternative is the same as estimated for
Alternative 4. The SVE component of this alternative would be identical to that described in
Alternative 2. The SVE treatment would be aimed at removing vapors in the vadose zone. These
vapors originate in part from PCE in the vadose zone, and to a greater extent from sources within the
saturated zone. Removal of vapors originating from the saturated zone will accelerate the rate of
aquifer remediation.
Based on data collected during the IRA, EPA will calculate the threat to groundwater from the
soil. EPA will also calculate the extent to which the SVE system accelerates groundwater cleanup.
EPA will cease SVE when the soil no longer poses a threat to groundwater and no longer accelerates
contaminant removal from groundwater. Treatment residuals will be managed in the same manner as
for Alternatives 1 through 4.
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7.4.6 Alternative 6: Air Sparging, SVE, and Groundwater Extraction and Treatment of Main
Source Area (1 Extraction Well); Monitoring and Evaluation of Downgradient Edges of
the Plume
This alternative combines the air sparging remedial component of Alternative 3, with the
groundwater pumping scope of Alternatives 4 and 5. The air sparging component would be exactly
as described for Alternative 3. By injecting air into the saturated zone, air sparging mobilizes
dissolved and adsorbed PCE into vapors, which can be collected using an SVE system. Although this
removal process would address much of the source area, there would still be segments of the
groundwater plume beyond the area addressed by the air sparging. As discussed for Alternative 3,
the area addressed by sparging would be the area addressed by SVE in Alternative 2 and 5, plus
additional areas characterized by high PCE concentrations (roughly corresponding to the 1,000 /ig/L
groundwater concentration contour in Figure 5-5). Although both the groundwater extraction
program and the vapor extraction program would have the same general aim of removing the most
contaminated portions of the saturated zone, the area designated for sparging is slightly different from
the area identified in Alternatives 4 and 5 (roughly the area delimited by the 1,000 /ig/L concentration
contour) for possible action by source area groundwater extraction. This is because groundwater
extraction and vapor extraction would be operated under different constraints. Because of the
presence of the car dealership and private residence to the south, and the Elk's Lodge to the north of
the original source areas, it would be difficult to implement air sparging in these areas. Although it
would be possible to install air injection wells in parts of these areas, provided the appropriate
easements are obtained, all injected air and mobilized contaminants must be recovered. This would
require placing the vapor recovery wells even further out from the source areas than the injection
wells, which may be difficult due to the placement of existing surface structures and other land
developments and uses.
The groundwater collection program, on the other hand, would be able to address a greater
area of saturated zone contamination. Because the groundwater extraction program would be
inherently an extraction program, rather than an injection and subsequent removal process, there are
fewer restrictions on placement of the wells to meet the remedial goals. Although accurate placement
is still preferred to most efficiently capture the contaminated groundwater, slight shifting of locations
to accommodate above-surface conditions will only minimally affect performance. On the other hand,
the air sparging wells must be more accurately placed in the areas of high concentration, and it is
more important and more difficult to collect all the mobilized contaminant vapors.
Because the air sparging would not address all the more highly contaminated areas potentially
acting as sources, this alternative would also include a groundwater extraction program like the one
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described for Alternatives 4 and 5. This would capture some of the contaminants beyond the zone
impacted by the air sparging program, and would complement the air sparging program in accelerat-
ing the remedial process in the main source area behind Halford's Cleaners. Treatment residuals
would be managed in the .same manner as for Alternatives 1 and 5.
7.4.7 Alternative 7: No Action
This alternative would call for no remedial measures to be performed at the site. Monitoring
would continue at the municipal wells to see if PCE or other contaminants are reaching these sources
of drinking water. No other action would be taken, nor would anything be done should contamina-
tion be detected in these wells, which would likely be shut down at that point.
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SECTION 8 ARARs
This section identifies potential applicable or relevant and appropriate requirements (ARARs)
for the remedial action selected.
8.1 Definition of ARARs
Section 121(d) of CERCLA requires remedial actions to attain federal or state environmental
standards, requirements, criteria, or limitations that are determined to be legally applicable or relevant
and appropriate (unless waiver of such compliance is justified). Federal ARARs may include
requirements under federal environmental laws. State ARARs may only include promulgated,
enforceable environmental or facility-siting laws that are more stringent or broader in scope than
federal requirements and that the State of California has identified to EPA in a timely manner.
An ARAR may be either "applicable" or "relevant and appropriate" but not both. If there is
no specific federal or state ARAR for a particular chemical or remedial action, or if the existing
ARARs are not considered sufficiently protective, then other criteria or guidelines "to be considered"
(TBC) may be identified and used to ensure the protection of public health and the environment. The
definitions of "applicable", "relevant and appropriate" and "to be considered", drawn from the NCP,
are presented below.
• Applicable requirements are those cleanup standards, standards of control,
and other substantive environmental protection requirements, criteria, or
limitations promulgated under federal or state environmental or facility siting
laws that specifically address a hazardous substance, pollutant, contaminant,
remedial action, location, or other circumstances found at the CERCLA site.
Only those state standards that are identified by a state in a timely manner
and that are more stringent than federal requirements may be applicable.
• Relevant and appropriate requirements are those cleanup standards,
standards of control, and other substantive environmental protection require-
ments, criteria, or limitations promulgated under federal or state laws that,
while not "applicable" to a hazardous substance, pollutant, contaminant,
remedial action, location, or other circumstances found 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 by a state in a timely manner and that are
more stringent than federal requirements may be relevant and appropriate.
• To be considered (TBCs) are those advisories, criteria, or guidance devel-
oped by EPA, other federal agencies, or states that may be useful in develop-
ing CERCLA remedies. The TBC values and guidelines may be used as
EPA deems appropriate.
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Table B-l in Appendix B analyzes the ARARs for EPA's preferred interim remedy at the
Modesto Ground Water Contamination Site. Additional ARARs, such as those discussed in the
Feasibility Study, may apply to the final remedial action at the Site. For example, ARARs consisting
of the standards to which the groundwater aquifer is to be remediated, may apply to the final remedial
action, but are beyond the scope of this interim remedial action during which EPA will evaluate the
feasibility of achieving groundwater standards throughout the aquifer.
8.2 Discussion of ARARs
In determining whether a requirement is applicable or relevant and appropriate, EPA
considers the hazardous substances present, the remedial actions contemplated, the physical character-
istics of the site, and other appropriate factors.
Pursuant to CERCLA § 121 and the National Contingency Plan (NCP), only substantive, not
administrative, requirements are ARARs, and federal, state, and local permits are not required for
those portions of a CERCLA cleanup that are conducted entirely on site, as long as those actions are
selected and carried out in compliance with CERCLA § 121.
Classification of ARARS. There are three classifications of ARARs: chemical-specific,
action-specific, and location-specific. These categories are defined below.
• Chemical-specific ARARs are health- or risk-based concentration limits,
numerical values, or methodologies for various environmental media (i.e.,
groundwater, 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.
• Action-specific ARARs are technology- or activity-based requirements that
are triggered by the type of remedial activities under consideration. Exam-
ples are RCRA regulations for waste treatment, storage, or disposal.
• Location-specific ARARS are limitations on certain types of activities based
on specific site characteristics. Federal and state location-specific ARARs
are restrictions placed on the concentration of a contaminant or the activities
to be conducted because they are in a specific location. Examples of special
locations possibly requiring ARARs are flood plains, wetlands, historic
places, and sensitive ecosystems or habitats.
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Identification of Potential ARARs. CERCLA and the NCR generally do not provide explicit
standards for determining whether a particular remedy will result in adequate cleanup at a particular
site. Rather, CERCLA recognizes that each site has unique characteristics and factors that must be
evaluated to determine which requirements are ARARs. Examples of such unique characteristics and
factors are exposure pathways, sensitive receptors, hazardous materials, and suggested remedial
alternatives.
Federal, California, and local requirements and criteria have been analyzed to determine
potential ARARs.
This section discusses ARARs for the site and issues related to them. The ARARs and TBCs
are depicted in Table B-l in Appendix B.
• Chemical-Specific ARARs: Treatment of Groundwater. Federal and state
MCLs are not ARARs for the aquifer cleanup standards for this interim
action because such a determination is outside the scope of this
interim/source remedy. Groundwater cleanup standards will be determined
in the final remedial action decision for the site. All alternatives except the
no-action alternative include groundwater extraction followed by treatment
and disposal of the treated groundwater. If disposal is off site, the disposal
must comply with federal and state requirements, but these are not consid-
ered ARARs under the NCP. Several possibilities exist for the disposal of
groundwater. If EPA discharges treated groundwater to the Modesto sewer
system, it will comply with the applicable permit requirements. EPA intends
to treat the pumped groundwater on site to the lowest detectable level, using
a detection limit of no more than 5 /tg/L (MCL for PCE).
If naturally occurring radiation is found in the extracted groundwater, that
groundwater will be treated to remove the naturally occurring radiation in
order to meet the City of Modesto's treatment standards for disposal to the
Modesto sewer system, although these requirements also are not ARARs.
• RWQCB Resolution No. 68-16 implements the federal Clean Water Act
nondegradation policy and limits discharges that will lead to degradation of
the beneficial uses of waters of the State of California. Resolution 68-16
will not be an ARAR if groundwater is disposed to a POTW because that is
an off-site disposal, and by definition, ARARs are on-site requirements.
Even if Resolution 68-16 applies to the discharge to the POTW as a govern-
ing law, EPA understands that the limits imposed by the POTW would meet
the requirements of Resolution 68-16. In any event, EPA will meet the
Resolution 68-16 nondegradation requirement waters of the State of Califor-
nia by treating groundwater contaminants to MCLs before any discharge,
thereby protecting the potential beneficial use of that groundwater as drinking
water.
Federal and state RCRA requirements will not be triggered by the disposal of treated
groundwater to the Modesto sewer system for two reasons: (1) the exemption for
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disposal to publicly-owned treatment works (22 CCR 66261.4(b), citing 40 CFR
261.4); and (2) EPA's exemption for contaminated media that has been treated to
health-based levels such as MCLs (e.g., EPA memorandum from Sylvia K.
Lowrance to Jeff Zelikson, January 24, 1989).
Chemical-Specific ARARs: Soil. No chemical-specific remediation numer-
ical standards currently exist for the vapor-phase remediation.
Although there are no ARARs that pertain to the soil, the risk assessment for this
site has shown that the risk posed by the soil vapors is within the acceptable EPA
risk range. However, soil vapor remediation will accelerate the rate of groundwater
remediation. Based on data collected during the IRA, EPA will calculate the threat
to groundwater from the soil. EPA will also calculate the extent to which the SVE
system accelerates groundwater cleanup. EPA will cease SVE when the soil no
longer poses a threat to groundwater and no longer accelerates contaminant removal
from groundwater.
Action-Specific ARARs. Organic contaminants, once removed by the
treatment process, may be considered hazardous wastes, and therefore may
be subject to certain RCRA-based action-specific ARARs (22 CCR, Division
4.5).
Location-Specific ARARs. No special characteristics exist at this site to
trigger any location-specific requirements. Therefore, EPA has determined
that there are no location-specific ARARs for the Modesto Ground Water
Contamination Site.
56
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SECTION 9 SUMMARY OF THE COMPARATIVE ANALYSIS
9.1 Comparison of Alternatives
This section summarizes the extensive comparative analysis of the seven alternatives presented
in the site Feasibility Study (FS), and also included in Section 7 herein. The FS evaluated each
alternative according to nine regulatory criteria specified by the NCR, which are discussed below.
The evaluation of the seven alternatives and the nine criteria is summarized on Table 9-1 at the end of
this section.
9.1.1 Overall Protection of Human Health and the Environment
This criterion addresses whether a remedy provides adequate protection of human health and
the environment, and describes how risks are eliminated, reduced, or controlled through treatment,
engineering controls, or institutional controls. Alternatives 1 through 3 are adequately protective of
human health and the environment by extracting and treating all known contaminated groundwater
exceeding MCLs. Alternatives 4 through 6 are adequately protective of human health and the
environment by directly extracting and treating substantial contamination, and by monitoring whether
the remaining contaminants reduce by natural attenuation. All six alternatives reduce potential site
risks posed by the possibility of future use of the groundwater as drinking water.
Future human health risks could result if contaminants migrate to drinking water supply wells
or if new drinking water wells are installed in the plume. Alternatives 1, 2, and 3 will employ a
more extensive groundwater extraction program to actively remediate all of the known contamination
within the plume above MCLs, whereas Alternatives 4, 5, and 6 actively remediate the most
contaminated portion of the plume, roughly the area within the 1,000 ppb contour shown on Figure
5.5. During this IRA, EPA will be monitoring the downgradient edge of the plume to determine
whether the remaining PCE will be removed through natural attenuation mechanisms. If the
monitoring reveals that natural attenuation is not occurring, the edges of the plume, which will be
delineated by the IRA, will be addressed in the final remedy.
Alternatives 2 and 5 use SVE and groundwater extraction to remove PCE from the saturated
vadose zone. The vadose zone may act as a source of continuing groundwater contamination;
however, the extent to which vadose zone PCE may act as a groundwater contamination source is
unknown. The vadose zone consists of sandy soil interlaced with many horizontal zones of low-
permeability clays and silts. This stratigraphy makes it difficult to accurately quantify PCE in the
soil, as contamination would accumulate to higher concentrations in clays and silts than in sandy
zones; PCE would migrate downward more easily in sand through the force of gravity. This leads to
57
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a complex concentration distribution. This complex structure also makes it difficult to accurately
model contaminant migration, even if comprehensive contaminant distribution is known. Despite the
obstacles to quantitatively predicting future impact of vadose zone PCE on the aquifer, the levels of
PCE measured (less than 1 mg/kg) and with PCE soil vapor present at less than 5 percent of PCE's
vapor pressure, in the vadose zone the potential for creation of new groundwater contamination from
vadose zone PCE would be low, compared to potential sources from saturated zone DNAPL.
On the other hand, SVE is likely to accelerate groundwater remediation. Much of the PCE in
soil gas may emanate from the contaminated groundwater and/or DNAPL in the saturated zone. By
removing the soil gas, concentration gradients between the soil gas and the subsurface sources will
increase, thus accelerating transfer of organic contaminants from the groundwater to the soil gas, and
to the SVE off-gas treatment system. This mechanism will operate in addition to the extraction of the
groundwater itself. Thus, the duration of groundwater remediation may be reduced by SVE in
Alternatives 2 and 5, increasing protection of human health and the environment provided by the
groundwater extraction components of these alternatives. Based on data collected during the IRA,
EPA will calculate the threat to groundwater from the soil. EPA will also calculate the extent to
which the SVE system accelerates groundwater cleanup. EPA will cease SVE when the soil no
longer poses a threat to groundwater and no longer accelerates contaminant removal from groundwa-
ter.
Alternatives 3 and 6 employ air sparging to accelerate the rate of contaminant removal from
the saturated zone. Supplementing groundwater extraction, air sparging mobilizes dissolved and
adsorbed contaminants in the groundwater into the vapor phase, from whence they would be collected
through an SVE system. This might decrease the time required to meet groundwater cleanup goals,
thereby protecting human health and the environment. However, because air sparging mobilizes
contaminants in an uncontrollable way, it may decrease protection of human health and the environ-
ment.
In summary, there are three distinguishing factors among the considered alternatives affecting
overall protection of human health and the environment. These are:
• Scope of groundwater extraction program;
• Use of SVE; and
• Use of air sparging.
58
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Alternatives 4, 5, and 6, with a smaller groundwater extraction system, will provide similar
protection as Alternatives 1, 2, and 3 with a larger groundwater extraction scope. All six alternatives
will protect human health and the environment by decreasing site risks. The SVE component
implemented with Alternatives 2 and 5 is expected to add benefit to the IRA by accelerating the
removal of contaminants from the subsurface, potentially reducing the duration of groundwater
treatment needed in the final remedy. Finally, air sparging technology offered by Alternatives 3 and
6 may uncontrollably release contaminants, and thus present a risk to human health and the environ-
ment.
9.1.2 Compliance with ARARs
This section addresses whether a remedy will meet all ARARs or federal and state environ-
mental statutes and/or provide grounds for invoking a waiver.
As discussed in Part I, Section 1.2 of this IROD, the EPA is addressing the Modesto Ground
Water Contamination Site with an IRA because it needs to collect additional data to determine if the
ARARs, especially aquifer remediation requirements, can be met.
Each of the alternatives meet ARARs applicable to the IRA, as discussed in Section 8.
Alternatives 2 and 5 may accelerate the removal of PCE from the subsurface, including the top of the
water table, and thereby reduce the time required to meet ARARs in the aquifer. Alternatives 3 and
6, which employ air sparging, might further accelerate the removal of PCE from the subsurface.
All of the action alternatives would discharge treated air and groundwater. The technologies
specified for each of these alternatives, including air stripping for groundwater treatment and carbon
adsorption for off-gas treatment, are capable of reliably attaining chemical-specific and action-specific
ARARs pertaining to releases to the atmosphere and discharges of treated groundwater and disposal of
treatment residuals (e.g., spent carbon).
9.1.3 Long-Term Effectiveness and Permanence
This section discusses the ability of a remedy to maintain reliable protection to human health
and the environment over time, once cleanup goals have been achieved.
A goal of all action alternatives is source control and protection of human health and the
environment, and to determine if reductions in organic contaminant concentrations to groundwater
cleanup standards throughout the region of the aquifer impacted by Halford's Cleaners can be
accomplished. As such, "long-term effectiveness and permanence" is not directly applicable to this
IRA. The actions comprising each of the action alternatives will be consistent with the final remedy
and will make significant progress towards achieving long-term, permanent remediation of the site
59
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after the final ROD. Because DNAPL is suspected to be present in the saturated zone, this may limit
the ability to permanently meet all applicable requirements in the final remedy.
For Alternatives 3 and 6, which employ air sparging, there are potential limitations in
effectiveness due to the heterogeneity of the subsurface, which cause unpredictable flow patterns of
the injected air for the sparging component of these alternatives.
Certain lower concentration downgradient areas of the groundwater plume will not be directly
addressed by Alternatives 4, 5,-and 6. However, with active remediation directly addressing an
estimated 90-to-95 percent of the mass of dissolved contaminants and hydraulically isolating the
source, the outlying areas of the plume will likely be addressed through natural attenuation processes.
EPA will monitor the outlying areas of the plume to determine if natural processes, which decrease
concentrations of PCE, are occurring. Thus, the remedial technologies implemented by these
alternatives will provide an effective approach that, as part of a final remedy, will be capable of
meeting applicable requirements, providing an effective long-term remedy.
9.1.4 Reduction of Toxicity, Mobility, or Volume
This refers to the anticipated ability of a remedy to reduce the toxicity, mobility, and volume
of the hazardous components present at the site.
All the action alternatives call for the removal of contaminants from the subsurface. By
significantly controlling the source of contaminants, all alternatives will reduce the mobility of
contaminants. Concentration of the contaminants onto carbon media following air stripping and SVE
constitutes a reduction in volume and mobility. Spent carbon will be sent off site for regeneration,
resulting in destruction of the adsorbed contaminants. This will constitute a reduction in toxicity.
Alternatives 4, 5, and 6 will include monitoring to observe whether natural attenuation
mechanisms are addressing approximately 5-to-10 percent of the remaining dissolved PCE in the
aquifer not extracted and treated. These mechanisms do not constitute reductions in mobility and
volume. However, because concentrations in the groundwater will be expected to decrease through
natural attenuation processes, the toxicity of the groundwater in these areas will be decreased.
Alternatives 3 and 6 call for the use of air sparging as an element in the collection of the
subsurface contaminants. If properly designed and executed, such a plan may accelerate the rate of
contaminant removal. However, as discussed in the Section 7.4.3, it may be difficult to properly
implement air sparging technology. Air sparging that is operated such that not all the generated
vapors are removed would result in the forced migration of contaminants, which may constitute an
increase in contaminant mobility above its previously adsorbed state.
60
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9.1.5 Short-Term Effectiveness
This section addresses the period of time needed to complete the remedy and any adverse
impacts on human health and the environment that may be posed during the construction and
implementation period until cleanup goals are achieved.
None of the alternatives poses any short term hazards to workers or the community.
However, Alternatives 3 and 6 could possibly present increased hazards to nearby residents or other
potential receptors in the area. This is due to the mobilization of contaminants in the saturated soil
via air sparging. It would be difficult to recover the vapors generated by the sparged air. Uncollect-
ed vapors could migrate to the surface where they may expose residents or other receptors. Because
of the unpredictable path of the mobilized contaminants, it is not known where such releases would
occur, if they occur. Thus it would be difficult to put in place a program to track such releases.
Because of the potential presence of DNAPL, treatment durations may extend indefinitely into the
future for all alternatives considered; and remedy duration will be addressed in the final remedy.
9.1.6 Implementability
This section discusses the technical and administrative feasibility of a remedy, including the
availability of materials and services needed to carry out a particular option.
Alternatives 1,2, and 3 require the installation of extraction wells on private property
hundreds of feet from the source area, and pumping the extracted groundwater through new, buried
conduits to a treatment facility near the source area. Because of the highly developed character of
this area, including many residences and businesses, this component of these alternatives may be
difficult to implement. Not only would installation of such facilities be disruptive to the nearby
residential areas, these facilities would require long-term easements from the property owners to
operate throughout the duration of groundwater treatment. To a limited extent, Alternatives 3 and 6
suffer from additional implementability limitations, as air sparging and vapor extraction wells would
have to be installed in the residential property adjacent to the site to implement the air sparging
component of this alternative. There are no significant implementability issues with regard to SVE
for Alternatives 2 and 5.
Based on these analyses, Alternatives 1, 2, and 3 are less implementable than Alternatives 4,
5, and 6, based on the limitations on installation of off-site extraction facilities and the increased
difficulty in disposal of higher volumes of treated water. Alternatives 3 and 6 would also require
installation of remedial equipment in a residential area, though not to the extent as the larger
groundwater extraction program called for by Alternatives 1, 2, and 3, presenting additional
implementability concerns.
61
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The extraction and treatment technology for groundwater remediation called for by all six
treatment alternatives is well proven and readily implementable. Pending approval of a discharge
permit by the City of Modesto, EPA will discharge to the City of Modesto's sewer system.
Alternatives 1, 2, and 3 may be harder to implement than Alternatives 4, 5, and 6 as they call for a
higher rate of pumping and discharge (140 gpm compared to 50 gpm). The City of Modesto's
POTW is currently operating at capacity and thus would be more open to accepting a lower rate of
treated groundwater discharge.
In the event that uranium exceeds the discharge permit requirements, uranium would be
removed via ion exchange prior to discharge to the sewer system. Although a reasonable and cost-
effective disposal solution is expected to be developed for this waste, its disposal could pose an
implementability limitation of each alternative.
Treatment residuals would consist principally of spent carbon from the off-gas treatment.
This material can be sent off site for regeneration /disposal. The carbon would adsorb radon during
operation. However, due to radon's short half-life (3.8 days), nearly complete dissociation prior to
regeneration/disposal could be achieved. Dissociation products would include the radionuclide lead-
210. However, the resulting levels of this radionuclide are expected to be about 10 /iCi/g or less,
which are not expected to complicate disposal options. Thus this issue is not expected to limit the
implementability of any of the alternatives.
9.1.7 Cost
This section evaluates the estimated capital costs and operation and maintenance (O & M)
costs of the alternatives.
The estimated costs for the action alternatives fall into three sets. Alternatives 1 and 4, which
call for groundwater treatment only, are less expensive than Alternatives 2 and 5, which include SVE.
All four of these alternatives are considerably less expensive than Alternatives 3 and 6, which include
air sparging. Air sparging adds capital costs for the injection network and for increased off-gas
treatment capacity. These additional requirements add nearly $2,000,000 to the capital costs of the
alternatives. O & M costs also increase substantially with air sparging. This is due to the increased
need for organic vapor recovery, as well as additional electrical power requirements. For costing
purposes, it was assumed that soil vapor extraction (without air sparging) would only be required for
one year until it is no longer effective, because complete vadose zone contaminants are removed
because no further decreases in extracted vapor concentrations appear possible, or because it appears
that SVE will not further assist the groundwater remedy's duration. On the other hand, it is assumed
that sparging of air into zones of DNAPL contamination would continue to produce significantly
62
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contaminated vapors throughout the 30-year horizon used to estimate present worth costs. Although a
reduction in expected off-gas PCE concentrations (from about 700 /*g/L to about 200 ^g/L) was
assumed after one year of operation, further reductions in concentrations and/or treatment durations
may be possible. Such further reductions would decrease the large estimated differences in present-
worth O & M costs between the sets of alternatives.
Comparison of Alternatives 4, 5, and 6 to Alternatives 1, 2, and 3 shows that decreasing the
scope of the groundwater collection and treatment program would reduce both the capital and O & M
costs. Capital costs are increased by approximately $73,000 for Alternatives 1, 2 and 3 due primarily
to the costs incurred to install an estimated three additional extraction wells in the outlying portions of
the plume and to pump them to a central treatment facility near the source area. O & M costs
increase more dramatically for these alternatives because of the per-gallon cost for disposal of the
treated groundwater to the City of Modesto sewer system. O & M costs after the first year of
operation increase by only approximately $26,000 for continued operation of the SVE system.
Treatment (as opposed to disposal) costs themselves do not dramatically increase for Alternatives 1,
2, and 3 as treatment costs are driven mainly by carbon regeneration costs. Despite the higher flow
rates for Alternatives 1, 2, and 3, there is not expected to be a significantly greater mass of PCE
treated, and thus carbon usage rates would not greatly increase.
The differential in O & M costs between Alternatives 1 through 3 and Alternatives 4 through
6 would be much greater if the EPA is required to treat uranium as part of the requirements of the
permit to discharge to the sewer system. The amount of uranium to be removed would be propor-
tional to the amount of water treated, and thus the O & M (and thus present worth) costs of uranium
removal for the higher flow rate Alternatives 1, 2, and 3 are much greater. The present worth cost
for uranium removal for Alternatives 1, 2, and 3 is estimated at $1,160,000 more than the present'
worth cost of Alternatives 4, 5, and 6.
9.1.8 State Acceptance
This section indicates whether, based on review of the information, the state concurs with,
opposes, or has no comment on the preferred alternative.
As previously stated, the State of California, through Cal-EPA's DTSC, and the RWQCB,
concur with the selected remedy.
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9.1.9 Community Acceptance
This section indicates whether community concerns are addressed by the remedy and whether
the community has a preference for a remedy. Although public comment is an important part of the
final decision, EPA is compelled by law to balance community concerns with all previously men-
tioned criteria. A summary of oral comments received at the public meeting held on July 29, 1997,
is included in Part 3. EPA received no oral or written comments objecting to the preferred remedy
during the Public Comment Period. EPA also did not receive any statements of preference for any
particular alternative. EPA believes the community accepts the chosen remedy.
SECTION 10 THE SELECTED REMEDY
Based on the comparative analysis conducted in the FS and summarized in the preceding
section, EPA has selected a remedy. The selected remedy (Alternative 5) includes groundwater
extraction with at least one single extraction well, located near the main source areas behind Halford's
Cleaners, and will eliminate the highest contaminant levels at the source area (source control) and will
hydraulically contain contaminants in the source area. The primary components of this remedy
include groundwater extraction, groundwater treatment by air stripping with carbon adsorption,
discharge of the treated groundwater, and SVE followed by carbon adsorption (see Figure 10-1). In
addition, although uranium is naturally occurring, and is a regional feature unrelated to this site for
which cleanup standards are not required, additional treatment of extracted groundwater to remove
uranium in order to satisfy disposal requirements may be necessary. Treatment may be required to
meet the City of Modesto's uranium pretreatment requirements if disposal is to the City's sewer
system, or to MCLs if disposal is to the City's drinking water system.
The extracted groundwater would be pumped to a treatment facility that would be located in
the open area behind Halford's Cleaners or nearby. Groundwater treatment would be by air
stripping, the preferred technology for this site. Air stripping could be accomplished either through a
packed tower, or through lower profile tray strippers. Either technique would produce effluent
concentrations at or below required discharge permit requirements. No aqueous-phase carbon
adsorption would be required to "polish" the effluent to meet cleanup standards. However, carbon
could be used to guard against untreated groundwater passing through the system during process
upsets. Such events could also be avoided with proper operational controls and interlocks. The need
for carbon would be determined in the design phase after final arrangements have been made for
treated groundwater discharge.
64
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Page I of 5
Table 9-1
SUMMARY OF INDIVIDUAL EVALUATIONS OF FINAL ALTERNATIVES
Criterion
Alternative 1
Groundwater Extraction and
Treatment (Four extraction
wells); Monitoring and Evalua-
tion of Downgradient Edge of the
Plume
Alternative 2
SVE and Groundwater Extrac-
tion Treatment (Four extraction
wells); Monitoring and Evalua-
tion of Downgrading Edge of the
Flume
dV^uiPRorecrf^::>^y ^ * *v •*
Human Heilth
Environment
No current groundwiter or soil
vapor exposure risks. Potential
future risks reduced through en-
traction and treatment.
Significant environmental risk not
anticipated.
No current groundwater or soil
vapor exposure risks. Potential
future risks reduced through ex-
traction arid treatment.
Significant environmental risk not
anticipated.
Chemical-specific
ARAKi
Action-specific ARARs
Operation of tail alternative as pin
of the IRA would help determine
whether chemical-specific AKARs
could be met.
No compliance issues are anticipat-
ed with respect to action-specific
ARARi.
Operation of this alternative as pan
of me IRA would help determine
whether chemical-specific ARARs
could be met.
No compliance issues ire anticipat-
ed with respect to action-specific
ARARs.
Alternative 3
Air Sparging, SVE, and Ground-
water Extraction and Treatment
(Four extraction wells); Monitoring
and Evaluation of Downgradlenl
Edge of the Plume
Alternative 4
Groundwater Extraction and
Treatment of Main Source Area
(One Extraction Well), Monitoring
and Evaluation of Downgradient
Edges of the Plume
Alternative 5
SVE and Groundwater Extraction
and Treatment of Main Source
Area (One Extraction Well),
Monitoring and Evaluation of
Downgradient Edges of the Plume
Alternative C
Air Sparging, SVE, and Groundwa-
ler Extraction and Treatment of
Main Source Area (One Extraction
Well), Monitoring and Evaluation of
Downgradient Edges of the Plume
Alternative 7
No-Action
*r*?lfe^"^ '' < <>^f|v:« , '.* - \
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Page 2 c
Table 9-1
SUMMARY OF INDIVIDUAL EVALUATIONS OF FINAL ALTERNATIVES
Criterion
Alternative 1
Groundwater Extraction and
Treatment (Four extraction
wells); Monitoring and Evalua-
tion of Downgndlent Edge of the
Plume
^praSMES '*' ** < . v '" • '/^ / ' v.pP^>
Because planned action is considered
interim, some residual risk will re-
main. However, the actions compar-
ing this alternative would be consis-
tent with the final remedy that would
minimize residual risk. Air sparging
may increase degree of potential
DNAPL removal but may spread
unruptured contamination, increasing
risk.
Due to heterogeneity of subsurface
soils, air sparging would not be reli-
able.
Yes
Because planned action is considered
interim, some residual risk will
remain. However, die actions com-
paring this alternative would be
consistent with the final remedy that
would minimize residual risk. Dur-
ing the IRA, outlying edges of the
plume will be monitored to ensure
that contaminant concentrations are
decreasing. Alternative does not
address PCE present in vadose zone.
However, concentrations in vadose
zone are low and do not pose signif-
icant risk.
Reliable method for controlling
majority of contamination at the
source area.
Yes
^^SfeF^c^»^^^8^WIW^^^^**^^4"t'^f* ' "" •' "X '-WS^'^.. :>'
Treatment process used
Amount destroyed or
created
Contaminant collection via air
stripping, concentration onto car-
bon, destruction through carbon
regeneration.
Alternttive would be' consistent
with the final remedy which would
probably treat groundwater plume
lo applicable requirements.
Contaminant collection via air
stripping and SVE, concentration
onto carbon, destruction through
carbon regeneration.
Alternative would be consistent
with the final remedy which would
probably treat groundwater plume
to applicable requirements. Va-
dose zone soil gas contamination
would be reduced.
Contaminant collection via air strip-
ping and air sparging/SVE, concentra-
tion onto carbon, destruction through
carbon regeneration.
Alternative would be consistent with
the final remedy which would proba-
bly treat groundwater plume to appli-
cable requirements. Vadose zone soil
gas contamination would be reduced.
Contaminant collection via air strip-
ping, concentration onto carbon,
destruction through carbon regenera-
tion.
Alternative would be consistent with
the final remedy which would proba-
bly treat groundwater plume to
applicable requirements. However,
approximately 5-10% of dissolved
PCE would not be destroyed, but
would disperse or be addressed in
the final RA.
Because planned action is considered
interim, some residual risk will
remain. However, the actions com-
paring this alternative would be
consistent with the final remedy that
would minimize residual risk. Dur-
ing the IRA, outlying edges of the
plume will be monitored to ensure
that contaminant concentrations are
decreasing. Outlying edges of
plume rely on natural attenuation
mechanisms to reduce concentra-
tions, which may increase the time
required to meet cleanup standards.
Reliable method for majority of
contamination of the source area and
most reliable method for expediting
vadose zone remediation.
Yes
V? s- -,- tv
Contaminant collection via air strip-
ping and SVE, concentration onto
carbon, destruction through carbon
regeneration.
Alternative would be consistent with
the final remedy which would proba-
bly treat groundwater plume to
applicable requirements. Vadose
zone soil gas contamination would
be reduced. However, approximate-
ly 5-10% of dissolved PCE would
not be destroyed but would disperse
or be addressed in the final RA.
Alternative 6
Air Sparging, SVE, and Groundwa-
ter Extraction and Treatment of
Main Source Area (One Extraction
WeH), Monitoring ind Evaluation of
Downgradlent Edfea of the Flume
V
Because planned action is considered
interim, some residual risk will remain.
However, the actions comparing this
alternative would be consistent with the
final remedy dial would minimize
residual risk. Air sparging may in-
crease degree of DNAPL removal.
During the IRA, outlying edges of the
plume will be monitored to ensure that
mntimin.nl concentrations are decreas-
ing. Outlying edges of plume rely on
natural attenuation mechanisms to
reduce concentrations, which may
increase the time required to meet
cleanup standards.
Reliable method for controlling; majori-
ty of contamination at the source area.
However, due to heterogeneity of
subsurface soils, air sparging would not
be reliable.
Yes
»>^;-' v£8$&' :'V:'' '^'
Contaminant collection via air stripping
and air sparging/SVE, concentration
onto carbon, destruction through car-
bon regeneration.
Alternative would be consistent with
the final remedy which would probably
treat groundwater plume to applicable
requirements. Vadose zone soil gas
contamination would be reduced.
However, approximately 5-10% of
dissolved PCE would not be destroyed
but would disperse or be addressed in
the final RA.
Alternative 7
No-Action
,;-<*?•" v ^
No change from
existing potential
risks.
No controls over
potential risks estab-
lished.
N/A
None
None
09:rzSOTO_SFI7«|MOD_IIOD_T» I.
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Page 3 of}
Table 9-1
SUMMARY OF INDIVIDUAL EVALUATIONS Of FINAL ALTERNATIVES
Criterion
Reduction of toxicity,
mobility, or volume
Irreversible treatment
Type and quantity of
residuals retraining after
treatment
Alternative 1
Groundwater Extraction and
Treatment (Four extraction
wells); Monitoring and Evalua-
tion of Downgradient Edge of the
Plume
Volume reduced through concen-
tration onto carbon. Touchy
reduced during carton regenera-
tion. Extensive groundwater ex-
traction program would reduce the
mobility of the plume by prevent-
ing it from migrating further.
Yes.
Spent carbon.
Alternative 2
SVE and Groundwater Extrac-
tion Treatment (Four extraction
wells); Monitoring and Evalua-
tion of Downgradlcnt Edge of the
Plume
Volume reduced through concen-
tration onto carbon. Toxicity
reduced during carbon regenera-
tion. Extensive groundwater ex-
traction program would reduce the
mobility of the plume by prevent-
ing it from migrating further.
Yes.
Spent carbon.
Alternative 3
Air Sparging, SVE, and Ground-
water Extraction and Treatment
(Four extraction wells); Monitoring
and Evaluation of Downgradient
Edge of the Plume
Volume reduced through concentra-
tion onto carbon. Toxicity reduced
during carbon regeneration. Air
sparging may uncontrollably increase
the mobility of some contaminants.
Extensive groundwater extraction
program would reduce die mobility of
the plume by preventing it from mi-
grating further.
Yes.
Spent carbon.
Alternative 4
Groundwater Extraction and
Treatment of Main Source Area
(One Extraction Well), Monitoring
and Evaluation of Downgradienl
Edges of the Plume
Volume reduced through concentra-
tion onto carbon. Toxicity reduced
during carbon regeneration. Mobility
of contaminants reduced through
source control. Approximately 3-
10% of dissolved PCE would not be
destroyed. However, natural attenu-
ation processes would reduce the
concentrations in, and thus the toxic-
ity of, the groundwater in these
areas or be addressed in the final
RA.
Yes.
Spent carbon.
Alternative S
SVE and Groundwater Extraction
and Treatment of Main Source
Area (One Extraction Well),
Monitoring and Evaluation of
Dowugradlenl Edges of the Plume
Volume reduced through concentra-
tion onto carbon. Toxicity reduced
during carbon regeneration. Mobili-
ty of contaminants reduced through
source control. Approximately 5-
10% of dissolved PCE would not be
destroyed. However, natural attenu-
ation processes would reduce the
concentrations in, and thus the toxic-
iry of, the groundwater in these
areas or be addressed in (be final
RA.
Yes. ,
Spent carbon.
Alternative 6
Air Sparging, SVE, and Groundwa-
ter Extraction and Treatment of
Main Source Area (One Extraction
Wefl), Monitoring and Evaluation of
Downgradienl Edges of the Pume
Volume reduced through concentration
onto carbon. Toxicity reduced during
carbon regeneration. Mobility of con-
taminants reduced through source
control. Approximately 5-10* of dis-
solved PCB would not be destroyed.
However, natural attenuation processes
would reduce (he concentrations In, and
thus the fDxidty of, ibe groundwater hi
these areas. Air sparging may uncon-
trollably increase the mobility of some
contaminants or be addressed in the
final RA.
Yes.
Spent carbon.
Alternative 7
No-Action
None
No.
N/A
0*rZMO*>_SFI»|MODJ>OO_T9J.D»«7«9/IW7-[>l
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Page 1 of
Table 9-1
SUMMARY OF INDIVIDUAL EVALUATIONS OF FINAL ALTERNATIVES
Criterion
Alternative 1
Groundwaler Extraction and
Treatment (Four extraction
wells); Monitoring and Evalua-
tion of Downgradlent Edf e of the
Plume
Community protection
Woricer protection
Environment impact
Time unWSttion rs
complete
ftpMUEMENTABILirv
Aviillbility of technolo-
gies
Availability of required
services, equipment,
materials, specialists and
labor
Ability to obtain approv-
als and coordinate with
other agencies
Ability to construct and
operate
Significant community risk not
anticipated.
No significant risk to workers if an
adequate safely program is fol-
lowed.
Significant environmental risk not
anticipated.
To be determined in final RA.
Ni- ,,;^;^s^?ISI
Readily available
Higher extraction rale compared to
other alternatives may impact
availability of discharge to the
POTW. whkh is already operating
ai capacity.
Problems not anticipated.
Proven construction and operation
methods exist. Construction of
extraction wells on privite property
hundreds of feet from source area
and pumping from that distance
may be difficult.
Alternative 2
SVE and Groundwafer Extrac-
tion Treatment (Four extraction
wells); Monitoring and Evalua-
tion of DowBfndlent Edge of the
Flume
Alternative 3
Air Sparging, SVE, and Ground-
water Extraction and Treatment
(Four extraction wells); Monitoring
and Evaluation of Downgradlent
Edge of the Plume
8^^^KSSilliPmf''''^'
Significant community risk not
anticipated.
No significant risk to workers if an
adequate safety program is fol-
lowed.
Significant environmental risk not
anticipated.
To be determined in final RA.
Js Xi>'\ ^" - 4 /""s* S N ~\
>v- * •-A'&Ss.^s&'.to .
Readily available.
Higher extraction rate compared to
other alternatives may impact
availability of discharge to the
POTW, which is already operating
at capacity.
Problems not anticipated.
Proven construction and operation
methods etiit. Construction of
extraction wells on private property
hundreds of feel from source area
and pumping from that distance
may be difficult.
Potential exists for some residential
exposure to vapors mobilized by the
air sparging system if this system does
not operate as designed due 10 hetero-
geneous subsurface conditions.
No significant risk to workers if an
adequate safery program is followed.
Significant environmental risk not
anticipated.
To be determined in final RA.
A-. .
Readily available
Higher extraction rale compared to
other alternatives may impact avail-
ability of discharge to the POTW,
which is already operating at capacity.
Problems not anticipated.
Construction of extraction wells on
private property hundreds of feel from
source area and pumping from that
distance may be difficult. Il is likely
impossible to icliably collect all va-
pors generated from sparging. These
may escape and potentially cause
exposure.
Alternative 4
Groundwater Extraction and
Treatment of Main Source Area
(One Extraction Well). Monitoring
and Evaluation of Downgradlent
Edges of the Plume
Significant community risk not
anticipated.
No significant risk to workers if an
adequate safety program is followed.
Significant environmental risk not
anticipated.
To be determined in final RA.
S" ' '• Oi.' & - v.,- ,
Readily available.
Readily available.
Problems not anticipated.
Proven construction and operation
methods exist.
Alternative 5
SVE and Groundwater Extraction
ind Treatment of Male Source
Area (One Extraction Well),
Monitoring and Evaluation of
Downgradient Edges of the Plume
Alternative 6
Air Sparging, SVE, and Groundwa-
ler Extraction and Treatment of
Main Source Ana (One Extraction
Well), Monitoring and Evaluation of
Downgradlent Edges of the Plume
Alternative 7
No-Action
' vv r'^'4V" * * * %o> L> *
> •- • spf^-'-A^Y^-
Significant community risk not
anticipated.
No significant risk to workers if an
adequate safety program is followed.
Significant environmental risk not
anticipated.
To be determined in final RA.
Readily available.
Readily available.
Problems not anticipated.
Proven construction and operation
methods exist.
Potential exists for some residential
exposure to vapors mobilized by the air
sparging system if this system does not
operate as designed due to heteroge-
neous subsurface conditions.
No significant risk to workers if an
adequate safery program is followed.
Significant environmental risk not
anticipated.
To be determined in final RA. .
' <«•*<•'&•$ -^kia^a.:
Readily available.
Readily available.
Problems not anticipated.
It is likely impossible to reliably collect
all vapors generated from sparging.
These may escape and potentially cause
exposure. Installation of air sparging
equipment in residential areas may be.
difficult.
Significant communi-
ty risk not anticipat-
ed.
No action requiring
workers.
Significant environ-
mental risk not antic-
ipated.
N/A
SUS ' - - .
N/A
N/A
N/A
N/A
5FI74JMOI\FOI\TV_I
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Page 5 of i
Table 9-1
SUMMARY OF INDIVIDUAL EVALUATIONS OF FINAL ALTERNATIVES
Criterion
Ability to monitor effec-
tiveness
Implementation of addi-
tional action if needed
Alternative I
Groundwaler Extraction and
Treatment (Four extraction
wells); Monitoring and Evalua-
tion of Downgradient Edge of the
Plume
Effectiveness can be easily moni-
tored by sampling groundwater
wells and treatment system efflu-
ent.
Additional extraction wells can be
installed as necessary.
Capital cost
First-year O & M cost
Subsequent year 0 & M
cost ^~—
Total 30-year present
worth
Capital cost for uranium
treatment, if required
O & M cost for uranium
treatment, if required
30-year present worth
for uranium treatment, if
required
$495.000
$207,000"
$172.000"
$2.902,000"
$265,000
$158.000
$2.440.000
Alternative 2
SVE and Groundwater Extrac-
tion Treatment (Four extraction
wells); Monitoring and Evalua-
tion of Downgradient Edge of the
Plume
Effectiveness can be easily moni-
tored by sampling groundwater
wells and treatment system efflu-
ent.
Additional extraction wells can be
installed as necessary.
Alternative 3
Air Sparging, SVE, and Ground-
water Extraction and Treatment
(Four extraction veils); Monitoring
and Evaluation of Downgradienl
Edge of the Plume
Effectiveness can be easily monitored
by sampling groundwater wells and
treatment system effluent. It is diffi-
cult to monitor the effectiveness of air
sparging.
Additional extraction wells can be
installed as necessary.
$1.023.000
J3I5.000"
$199.000"
$3,872.000"
$265.000
$158.000
J2, 440.000
$2.883.000
$737,000"
$388,000"
$8.571.000"
$265.000
$158.000
$2,440.000
Alternative 4
Groundwater Extraction and
Treatment of Main Source Area
(One Extraction Well), Monitoring
and Evaluation of Downgradienl
Edges of the Plume
Effectiveness can be easily moni-
tored by sampling groundwater wells
and treatment system effluent.
Additional extraction wells can be
installed as necessary.
Alternative S
SVE and Groundwater Extraction
and Treatment of Main Source
Area (One Extraction Well),
Monitoring and Evaluation of
Downgradient Edges of the Plume
Effectiveness can be easily moni-
tored by sampling groundwater wells
and treatment system effluent.
Additional extraction wells can be
installed as necessary.
'
$422,000
$153.000
$119.000
$2.088.000
$159,000
$81.000
$1.279,000
$950,000
$261.000
$144.000
$3,058.000
$159.000
$81.000
$1,279.000
Alternative 6
Air Sparging, SVE, and Groundwa-
ter Extraction and Treatment of
Mala Source Are* (One Extraction
Well), Monitoring and Evaluation of
Downgradienl Edges of the Plume
Effectiveness can be easily monitored
by sampling groundwater wells and
treatment system effluent. It is difficult
to monitor the effectiveness of air
sparging.
Additional extraction wells can be
installed as necessary.
$2,840.000
$689.000
$338.000
$7,844,000
$159,000
$81.000
$1,279.000
Alternative 7
No-Action
N/A
N/A
l^P^Sixl*::
$0
$5,200
$5,200
$71 ,000
-
-
—
1 Higher 0 & M and present worth costs compared to corresponding lower flow rate alternatives primarily due to (he unit cost of discharging treated ground water to the sewer.
-------
Groundwater
| Pump and Treat
EXTRACTION
WELL
at the
"HOT SPOT'
Clean Treated
Air Vented to
Atmosphere
Air
Stripping
to Remove
Tetrachlorethene
(PCE)
HALFORD'S
CLEANERS
Clean Water
to Sewer
System
Sewer Main
Figure 10-1
Schematic Illustration of the Selected Remedy
-------
Vapor-phase carbon would be used in this alternative to treat off gas from the air stripper.
This carbon would remove organic compounds from the off gas. The vapor phase carbon would also
adsorb radon gas stripped from the groundwater. However, because of the short-half-life of radon, it
would dissociate substantially. Spent carbon would either be regenerated or disposed.
Pending approval of the discharge permit by the City of Modesto, the treated groundwater
would be discharged to the City of Modesto sewer system. An existing sewer line located behind
Hal ford's Cleaners could be used for this discharge. In the event EPA cannot meet discharge permit
requirements for uranium, an ion exchange unit would be added to treat the groundwater prior to
discharge. The costs for the uranium removal are presented as a separate component. Since the ion
exchange treatment would be an add-on component to the treatment process, and its costs are not
affected by other components of the treatment train, the capital, O & M, and present worth costs for
ion exchange treatment of uranium can be simply added to the capital, O & M, and present worth
costs of this or other alternatives as otherwise developed.
It is difficult to estimate the duration of treatment required to meet the cleanup objectives for
the final remedy with this alternative. Estimation of the duration, and indeed treatment itself, is
hampered by the suspected presence of DNAPL in lower permeability silts near the top of the
groundwater table. The potential presence of DNAPL could represent a continuing source of
contamination to both the groundwater and the soil gas. Although the groundwater recovery program
is intended to remove contamination adsorbed within these zones, removal rates would be limited by
low diffusional transport rates out of the low permeability zones and into the higher permeability
zones where greater removals via convection could be accomplished. For cost estimation purposes, it
is assumed that the groundwater treatment components of remediation would be required throughout
the entire 30-year time horizon that contributes significantly to the present worth of the alternative.
The actual duration of treatment until remedial action objectives are met may be longer. Through the
operation of an IRA under an IROD, information will be developed that will allow a better estimate
of treatment duration.
The capture area for groundwater would be roughly that area within the 1,000 ppb contour.
The regions of the plume beyond the capture area would not undergo active remediation during this
IRA. With the source of contamination hydraulically contained at the start of the remedy, and
substantially or completely removed over time, concentrations in the plume beyond the capture area
will gradually decrease through natural attenuation and dispersion, and to a lesser extent, volatiliza-
tion. The presence of detectable amounts of PCE in soil gas in the vadose zone above entire regions
of the plume indicates that the volatilization mechanism is active at the site. (This transfer to the gas
phase has not been observed to create any exposure threats through inhalation to potential receptors
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above the plume.) Monitoring of these outlying areas would be conducted to ensure that concentra-
tions decrease through these natural attenuation mechanisms upon source area remediation. The
degree to which PCE concentrations decrease in these outer portions of the plume would be
documented by data gathered during the operation of the IRA.
SVE would both remove PCE from the vadose zone so that it would no longer act as a
potential source of groundwater contamination, and, more importantly, remove PCE vapors emanat-
ing from the top of the saturated zone, thus accelerating groundwater cleanup. Since vadose zone
contamination is likely to be originating from groundwater contamination, SVE treatment will focus
on areas where PCE discharge occurred, behind Halford's Cleaners. Precise locations of SVE wells
will be influenced by existing buildings, other structures, and property uses in the area will be
determined during the design phase. Based on data collected during the IRA, EPA will calculate the
threat to groundwater from the soil. EPA will also calculate the extent to which the SVE system
accelerates groundwater cleanup. EPA will cease SVE when the soil no longer poses a threat to
groundwater and no longer accelerates contaminant removal from groundwater.
The SVE system will consist of a combination of wells screened in different zones, based on
their soil type and, hence, permeability. Much vadose zone PCE contamination may be expected to
be found in lower permeability silty lenses. Yet simply placing SVE wells in the subsurface would
draw most of their vapor from the higher permeability sandy soils. Thus, wells must be placed in
each of these types of soil formations and operated alternately and separately to recover the maximum
amount of vadose zone contaminants. Based on the projected area of SVE treatment and the
estimated radii of influence, approximately 13 wells would be placed in sandy soils, and 13 wells
placed in lower permeability silty or clayey soils.
To maximize recovery of contaminants from the different soil types, wells in the higher
permeability and lower permeability regions would be operated separately on an alternating basis.
Any continuous operation scheme would tend towards drawing contaminants solely from lower
permeability zones, even if wells were installed only in the silty/clayey zones. Based on interpreta-
tion of modeling results, the total flow rate from the wells would range from about 500 scfm while
drawing from the sandy soils to 150 scfm while drawing from the lower permeability soils.
Measured soil gas data are used to provide an estimate of expected soil gas concentrations. Using this
approach, the assumed SVE gas concentration was calculated to be about 350 ^g/L. Better estimates
of actual achievable extracted soil gas concentrations could be measured during operation of the IRA.
Vapors generated by both the air stripping and the SVE system would be treated by vapor
phase carbon adsorption. A pair of units each consisting of two carbon beds, each containing about
2,000 Ibs of carbon would be suitable to remove all the organic vapors from the off-gasses. The
72
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carbon would have to be replaced at intervals of 10 days at the start of remedial operations. The
interval between changeouts would increase as contaminant concentrations decrease in the subsurface.
Treated off-gas would be discharged directly to the atmosphere at the site within acceptable air
contaminant prevention requirements. The carbon would also capture and remove radon gas stripped
from the ground water.
Considerably less contamination is present in the vadose zone than in the saturated zone.
Therefore, the SVE component of this alternative would require considerably less time to implement
than groundwater extraction and treatment. For costing purposes, it is assumed that only one year of
SVE operation would be required until the remedial action objectives were attained, namely that PCE
concentrations in the extracted gas either drop to non-detect, or have asymptotically plateaued,
indicating that the extent of feasible soil gas extraction has been reached or that SVE no longer assists
the groundwater remedy.
If removal of naturally occurring uranium is required to meet discharge requirements for
treated groundwater, the ion exchange treatment system would use ion exchange columns, packed
with anion exchange resin, in series to remove the uranium oxide/carbonate complexes from the
groundwater. Resin usage rates were conservatively estimated assuming uranium was encountered at
the higher concentrations seen in MW-6 and MW-7 at the farther edges of the plume. Spent resin
would be disposed of rather than regenerated because regeneration would produce a liquid radioactive
waste that would only have to be resolidified before disposal. Although this removal technique is
easy and straightforward to implement, several options exist for disposal of the spent resin, and these
can vary considerably in cost. Until the process is implemented, it is difficult to predict which of
these approaches would be used, as such disposal arrangements are done on a case-by-case basis.
The options for disposal of the resins include disposal in a low-level radioactive waste (LLRW)
facility, or, as presented in the EPA guidance document Suggested Guidelines for Disposal of
Drinking Water Treatment Wastes Containing Radioactivity (June 1994), in a RCRA hazardous waste
facility. Commitments by disposal facilities on acceptability and costs of disposal can only be made
as EPA prepares to actually dispose of these materials.
For costing purposes, it was assumed that spent resins would be disposed of at a LLRW
facility. A number of avenues were explored for disposing of the spent resins. Disposing of the
spent resins involves removal of the resins from the ion exchange tanks, performing any pretreatment
that might be required (such as dewatering), transportation, and disposal.
Total capital costs for this alternative without uranium treatment are estimated at about
$950,000. O & M costs are estimated to range from $261,000 the first year (with the SVE system
operating and the highest levels of PCE in the extracted groundwater being treated) to $144,000 in
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subsequent years, with no more SVE treatment and assuming concentrations in the extracted
groundwater would drop to half those observed in the first year. The present worth of this alternative
is estimated at about $3,060,000.
If ion exchange treatment were required for removing uranium from the treated groundwater
prior to disposal, then additional costs would be incurred. These additional costs are estimated to be
a capital cost of $159,000 and an annual O&M cost of $81,000, for a 30-year present worth cost of
$1,280,000.
During the IRA, operation of the extraction well will draw groundwater in the most
contaminated, source-area portions of the plume to the well, thus inhibiting downgradient migration of
those source-area contaminants.
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SECTION 11 STATUTORY DETERMINATIONS
The applicability and compliance of the following statutory determinations are addressed in
this section:
• Protectiveness
• Applicable or Relevant and Appropriate Requirements
• Cost-Effectiveness
• Use of Permanent Solutions, Alternative Treatment, or Resource Recovery
Technologies
• Preference for Treatment as a Principle Element
11.1 Protectiveness
The IRA protects human health and the environment from the groundwater exposure pathway.
Currently, the City is not supplying water from the area of groundwater contamination. However,
future human health risks could result if contaminants continue to migrate to drinking water supply
wells or if new drinking water wells are installed in the plume which may present an imminent and
substantial endangerment to human health or the environment. This alternative would remove the
source of groundwater contamination through vapor and groundwater extraction, which would prevent
migration from the source areas to drinking water supply wells. Wells in the outlying portions of the
plume would be monitored during implementation of the IRA. In the event that PCE concentrations
do not decrease from natural physical processes, the final ROD would include actions to directly
address these portions of the plume.
Site security and institutional controls will be implemented during this IRA to enhance
protection to human health and the environment.
There are no short-term threats associated with implementation of the selected remedy that
cannot be mitigated. Further, no adverse cross-media impacts are expected from the remedy.
11.2 Compliance with ARARs
The ARARs governing this interim remedial action include chemical and action-specific
regulations concerning the discharge of treated air from the air stripper, the discharge of treated
groundwater, and the disposal of any treatment residuals that may be considered hazardous waste.
75
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These ARARs are listed in Table B-l in Appendix B. This interim remedial action will attain or
comply with these ARARs.
11.3 Cost-Effectiveness
The selected remedy provides overall effectiveness proportionate to its costs and represents a
reasonable value. The remedy is cost-effective because it protects human health and the environment
by significantly controlling the source of contamination for a lower relative cost than other alterna-
tives. Although some alternatives may remove more contamination, this alternative provides for
effective source control at lower costs. Also, relatively low quantities of treated water will be
discharged to the sewer system, which reduces cost and minimizes additional loading at the Modesto
wastewater treatment plant.
11.4 Use of Permanent Solutions, Alternative Treatment, or Resource Recovery Technologies
The selected remedy uses permanent solutions and treatment technologies to the maximum
extent practicable to control the source of the contamination. The selected alternative will reduce the
toxicity and mobility of contaminants through groundwater extraction, treatment, and discharge.
Although other alternatives may offer a somewhat higher degree of long-term effectiveness and
permanence for groundwater remediation, this alternative will significantly control the source of the
contamination and represents the best balance of tradeoffs among alternatives with respect to the
pertinent criteria given the limited scope of the action.
11.5 Preference for Treatment as a Principle Element'
By treating extracted groundwater and soil vapor to address the threat by the site, the
statutory preference for treatment as a principal element is satisfied by the selected interim remedy.
The remedy employs air stripping, soil vapor extraction and carbon treatment units which should
significantly control the source of contamination. The final decision document for this site will more
completely and definitively address this preference.
SECTION 12 DOCUMENTATION OF SIGNIFICANT CHANGES
EPA issued the Proposed Plan (PP) for this remedy at the Modesto Ground Water Contamina-
tion Site for public comment in July 1997. The Proposed Plan identified Alternative 5, SVE, and
Groundwater Extraction and Treatment of Main Source Area (1 Extraction Well); Monitoring and
Evaluation of the Downgradient Edge of the Plume, as the preferred alternative. EPA reviewed all
written and verbal comments submitted during the public comment period. After reviewing these
76
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comments, EPA has determined that no significant changes to the remedy, as originally identified in
the Proposed Plan, are necessary.
77
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PART 3 - RESPONSIVENESS SUMMARY
Introduction
This section presents public concerns regarding the selected remedy identified during the
public comment period. The public comment period began July 14, 1997, at which time the Proposed
Plan was mailed to concerned citizens and other members of the community; the availability of the
Proposed Plan and the time and place of the public meeting were advertised in the Modesto Bee on
July 14, 1997. The public meeting was held at the Modesto Senior Citizens Center at 211 Bodem
Street in Modesto on July 29, 1997. The meeting format consisted of a formal presentation by EPA,
followed by a question and answer period. The meeting was recorded using a cassette tape recorder.
Questions from the community and corresponding responses are presented in this section. In some
cases, questions and responses are paraphrased. Cal EPA and City of Modesto personnel also
responded to some questions.
The transcript of the public meeting will be made available upon written request. An audio
cassette copy is available in the Administrative Record.
Oral Comments from the Public Meeting
Q: "How is this system going to address the uranium problem that I'm reading about? ... What
does this system do to take the uranium out?"
Oral Response:
R: "... In the feasibility study, we've built in a contingency, and are currently negotiating a
discharge permit with the city of Modesto. They will give us discharge requirements that we
cannot exceed, and we'll be monitoring our discharge for uranium as well as PCE and other
constituents."
"If we were to exceed the concentration for uranium that the city sets up for us ... we've set
up a contingency system where we would put an ion exchange unit on to the treatment train,
where we will be adding into the system that will be treating for uranium ... and that is
naturally occurring. We don't address that because it is a naturally occurring constituent ... If
this were a nuclear power plant, that would definitely be a major portion of this remedy.
But because it is naturally occurring we need to address it only in so far as cleaning up the
PCE."
Additional Information:
Accordingly, in the IROD, it is stated that the ion exchange .treatment system would use ion
exchange columns, packed with an ion exchange resin, in series to remove the uranium
oxide/carbonate complexes from the pumped and treated groundwater.
78
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Q: Wasn't that the reason in 1995 that it (Well 11) was shut down?
Oral Response:
R: "That was the reason that Municipal Well 11 was shut down in 1995. It didn't have to do
with PCE. The city had put a treatment unit on that particular well to take out the PCE
... but what they found was they had levels of uranium that exceeded the state/federal require-
ment."
Additional Information:
As stated in the ROD, Well 11 operated intermittently until October 1995 when the City
indefinitely deactivated it due to naturally occurring levels of uranium above the MCL of 20
pico curies per liter (pCi/L).
Q: Shouldn't this, right at the start, be addressed? In 1995 they had this high uranium and they
shut the well down because of it ... Isn't there still going to be an ongoing problem with
uranium?
Oral Response:
R: "...Not necessarily. It is my understanding that the city ... may even bring municipal Well
11 back on line, because the uranium levels have dropped ...."
Additional Information:
Moreover, as stated in the IROD, the uranium is naturally occurring and is a regional feature
unrelated to the site for which ground water cleanup standards are not required.
Q: Is it true that Well 11 will go back on line?
Oral Response:
R: "If, and only if it meets federal and state standards. They are continuing to monitor that....
But the uranium concentrations have dropped."
Q: How much would you say?
Oral Response:
R: "I would have to check."
"Uranium concentrations become very high if you pump a lot of water .... Well 11 was
pumping for years before it became problem
"Municipal Well was pumping at about the rate of 1,200 gal per minute .... and we're going
to be pumping at 50 gallons per minute ..."
"Uranium doesn't have a tendency to be very mobile either. So, you may have a pocket of
high uranium levels in one area, and not necessarily see it in another area."
79
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Q: So what you're saying is this pumping system is only going to be run to do a purification.
The City isn't going to go back on line using the well during the cleanup period?
Oral Response:
R: "... If I'm understanding you correctly, there may be two different issues. We may go ahead
and implement this remedial action and the city may say ... the water is fine so we're going
to start pumping Municipal Well 11."
Q: ...Looking at this layout that you have for the'system that's going to go on the back end of
the property, how much area is that going to cover and will the tenants from the other side of
that building still have adequate parking to run their business?
Oral Response:
R: "....What I can tell you right now about the placement of the system is that it will be in the
general area of Halfords. We're not sure exactly where we are going to put it ..."
"This is something we are having internal discussions about...
"Of course if it were on or near your property we would be negotiating and having discus-
sions with you."
Q: At this point it doesn't look like its going to be on the (Halford's Cleaners) property?
Oral Response:
R: "I am not sure on that ... The standard treatment unit size is 20 x 10 feet and 8 feet high.
There may be two of these."
Q: What is the time frame for treatment?
Oral Response:
R: "After collecting data, we'll have a much better idea of the time frame for operating the
system. It will be more than a few years ... I can tell you that."
As indicated in the ROD, it is difficult to estimate the duration of treatment required to meet
the cleanup objectives for the final remedy with this alternative. Estimation of the duration,
and indeed treatment itself, is hampered by the suspected presence of DNAPL in lower
permeability silts near the top of the groundwater table. The potential presence of DNAPL
could represent a continuing source of contamination to both the groundwater and the soil gas.
Although the groundwater recovery program is intended to remove contamination adsorbed
within these zones, removal rates would be limited by low diffusional transport rates out of
the low permeability zones and into the higher permeability zones where greater removals via
convection could be accomplished. For cost estimation purposes, it is assumed that the
groundwater treatment components of remediation would be required throughout the entire 30-
year time horizon that contributes significantly to the present worth of the alternative. The
actual duration of treatment until remedial action objectives are met may be longer. Through
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the operation of an IRA under an IROD, information will be developed that will allow a
better estimate of treatment duration.
Written Comments
This section summarizes and responds to the written comment EPA received. EPA received
only one written comment on the proposed remedy.
Comment: The figure diagrams in the Proposed Plan do not show the exact location of the
sewer lateral nor the direction of flow of the sewer lateral.
Response: The sewer lateral runs north-south, parallel to McHenry Avenue, behind the Elks
Lodge property, Hal ford's Cleaners, and the neighboring properties. The flow is
to the south. The lateral joins the main sewer at Griswold Avenue, where flow
turns to the west.
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PART 4 - BIBLIOGRAPHY
City of Modesto Groundwater Investigation: Summary Report on the Records Search and Business
Interviews, California Department of Health Services, Northern California Section (DHS-
NCS), Doc. Control No. 87-214-123-07-11 (Radian), June 3, 1987.
Cohen and Mercer, 1993. DNAPL Site Evaluation. CK Smolev, Boca Raton, Florida.
Dry Cleaners - A Major Source of PCE in Groundwater, Central Valley Regional Water Quality
Control Board, March 27, 1992.
Ecology and Environment, Inc. (E & E), 1997, Feasibility Study for the Modesto Groundwater
Contamination Site, Modesto, California, prepared for EPA Region 9, June.
, 1997, Baseline Human Health Risk Assessment, Modesto Groundwater Contamination
Site, Modesto, California, prepared for EPA Region 9, July.
Guide to Developing Superfund No Action, Interim Action, and Contingency Remedy RODs, U.S.
EPA Office of Solid Waste and Emergency Response Publication 9355.3-02FS-3, April 1991.
Interim Final Guidance on Preparing Superfund Decision Documents, U.S. EPA OSWER Directive
9335.3-02, October 1989.
Page, R.W. and Balding, C.O., Geology and Quality of Water in the Modesto-Merced Area San
Joaquin Valley, 1973.
Phase 1 Remedial Investigation Report, Modesto Groundwater Contamination Site, EPA Region 9,
Doc. Control No. ZS6045.1 (Ecology and Environment, Inc.), January 25, 1993.
Phase 3 Remedial Investigation Report, Modesto Groundwater Contamination Site, EPA Region 9,
Doc. Control No. ZS6101.1.1 (Ecology and Environment, Inc.), December 20, 1996.
Record of Decision Checklist for Interim Ground Water Actions, U.S. EPA Office of
Emergency and Remedial Response, Undated.
Suggested Guidelines for Disposal of Drinking Water Treatment Wastes Containing Radioactivity
(June 1994) EPA.
Suggested ROD Language for Various Ground Water Remediation Options, U.S. EPA OSWER
Directive 9283.1-03, Undated.
U.S. Environmental Protection Agency (EPA), 1993, Presumptive Remedies: Site Characterization
and Technology Selection for CERCLA Sites with Volatile Organic Compounds in Soils, EPA
OSWER Directive 9355.0-48.0-49FS, EPA/540-F-93-035.
, 1996, Presumptive Response Strategy and Ex-Situ Treatment Technologies for
Contaminated Ground Water at CERCLA Sites", EPA OSWER Directive 9283.1-12, EPA
540/R-96/023.
82
-------
, Drinking Water Standards And Health Advisories Table, 1996, November.
, 1991a, Update on OSWER soil lead cleanup guidance, Memorandum from Don R.
Clay, Assistant Administrator, Office of Solid Waste and Emergency Response, 29 August,
1991, OSWER Directive 9355.0-30.
83
-------
APPENDIX A
INDEX OF DOCUMENTS IN THE ADMINISTRATIVE RECORD
-------
Page 1
07/10/97
Modesto Groundwater Contamination
Modesto. California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER .
AR *
ROLL * FRAME #
DATE
yy/mm/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 1 01
AR 2 01
0001 00/00/00 Ecology I Environment.
Inc
0017 00/00/00
AR 3
01
0025 81/07/00
Clark Londquist
US Oept of the Interior
Geological Survey
Memo: Site history,
w/well sampling data
Enforcement plan
alternatives for cleanup
t abatement of
perchloroethytene fr
HaIford Dry Cleaners
operations
Digital model of
unconsol(dated aquifer
system in Modesto area
Stanislaus ft San Joaquin
counties
AR 4
AR 5
01
01
0036 86/07/28
0371 86/09/15 Gail Wax Peggy Harris
City of Modesto - Dept of CA Dept of Health
Utility Services Services - Toxic
Substances Control Div
AR 6
AR 7
AR 8
01
01
01
0374 87/02/19 Radian Corp
0398 87/02/19 Radian Corp
0433 87/06/03 Radian Corp
AR 9
AR 10
01
01
0539 87/06/03 CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
0647 87/06/05 Radian Corp
CA Oept of Health
Services - Toxic
Substances Control Oiv
CA Dept of Health
Services • Toxic
Substances Control Div
CA Oept of Health
Services • Toxic
Substances Control Div
Radian Corp
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
HRS package (ref A-P)
Ltr: Soil tests inside
Halford but Iding •
transmits wellhead
diagrams ft usage map for
property near well *11,
u/map only
Final rpt health ft safety
plan (HSP), City of
Modesto groundwater ftI
Final rpt risk assessment
for groundwater, phase 1,
City of Modesto gw RI
Sunaary rpt on records
search & business
interviews. City of
Modesto groundwater
investigation, w/maps
Final sunoary rpt re
records search ft business
interviews (PRP search).
w/apps A-E ft maps
Geologic surinary rpt, RI
AR 11
01
0680 87/07/31 Radian Corp
CA Dept of Health
City of Modesto
-------
Page 2
07/10/97
Modesto Grounduater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE IKOEX
AR NUMBER ORDER
AR «
ROLL * FRAME *
DATE
yy/on/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 12
01
0751 88/07/29 Radian Corp
AR 13
AR 14
AR 15
AR 16
AR 17
01
01
01
01
01
0773 88/10/13 Radian Corp
0825 88/10/13 Radian Corp
0877 89/03/20 Radian Corp
0942 89/09/16
Victor tzzo
CA Regional Water
Pollution Control Board
*5
0957 90/02/28 Planning Research Corp
AR 18
90/03/07
Ecology A Environment,
Inc
AR 19
AR 20
01
01
1007 90/04/15
1016 90/04/15
Services • Toxfc
Substances Control Div
CA Dept of Health
Services - Toxic
Substances Control Div
CA Dept of Health
Services • Toxic
Substances Control
Div
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
CA Dept of Health
Services - Toxic
Substances Control
Div
Environmental Protection
Agency - Region 9
Environmental Protection
Agency • Region 9
Jerry Clifford
Environmental Protection
Agency - Region 9
Jerry Clifford
Environmental Protection
Agency • Region 9
Shantilal Jamnadas
HaIford's Cleaners
Steven Lyon
Conklin Bros
groundwater
investigations
Final rpt on follow-up
interviews t records
search for City of
Modesto groundwater
investigation
Final rpt on follow-up
interviews t records
search. City of Modesto
groundwater investigation
Final grounoVater
investigation rpt re
follow-up interviews (PRP
search)
Draft final rpt for City
of Modesto groundwater
investigation
Dry Cleaners, major
source of PCE In
groundwater, w/maps
Final responsible party
(PRP) search for
nunictpal well fll, w/TL
to C Davis fr S Uald
2/28/90
Proposed workplan for
Modesto municipal well
fll site assessment
project (privileged, FOIA
exs 4 t 5)
Ltr: General
notice/104(e) request for
information, w/o nail
receipt *P841396391
ttr: General
notice/104(e) request for
information, w/o mail
receipt I»P841396393
-------
Page 3
07/10/97
AR t ROLL * FRAME
DATE
yy/m/dd
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AUTHOR
ADDRESSEE
SUBJECT
AR 21 01 1024
AR 22 01 1032
AR 23 01 1040
AR 24 01 1048
AR 25 01 1050
90/04/16 Jerry Clifford
Environmental Protection
Agency - Region 9
90/04/16 Jerry Clifford
Environmental Protection
Agency • Region 9
90/04/16 Jerry Clifford
Environmental Protection
Agency - Region 9
90/06/15 Russel Tonda & Diane
Tonda
Halford'c Cleaners
90/07/02 Robert Fores
Gtanelli, Brew & Mayol
AR 26 01 1052
90/07/02 Robert Fores
CtanelU, Brew ft Mayol
AR 27 01 1054 90/07/16
AR 28 01 1056 90/08/17
AR 29 01 1061 90/08/17
Robert Fores
Gianelli, Brew ft Mayol
Susan Lyon
Susan
Conklin Bros
Russell Tonda
Halford's Cleaners
Diane Tonda
Halford'c Cleaners
Environmental Protection
Agency - Region 9
Clifford Davis
Environmental Protection
Agency - Region 9
Clifford Davis
Environmental Protection
Agency - Region 9
Clifford Davis
Environmental Protection
Agency - Region 9
Ltr: General
notice/104(e) request for
information, w/o nail
receipt «P841396392
'Ltr: General
notice/104(e) request for
information, w/o nail
receipt *P841396395
Ltr: General
notice/104(e) request for
information, w/o nail
receipt *P841396394
Ltr: Response to 104(e)
Itr of request,
w/insurance policies
(privileged, FOIA ex 4)
Ltr: Response to general
notice/104(e) request for
information of 4/16/90 re
Shantilal Jannadas,
u/attchs (privileged,
FOIA ex 4)
Response to general
notice Itr re Shantilal
Jamnadas, financial
information (privileged,
FOIA ex 4)
Ltr: Response to 104(e)
Itr of request,
w/flnancial information
(privileged, FOIA ex 4)
Victor Izzo Jerry Bruns Memo: Well investigation
CA Regional Water Quality CA Regional Water Quality program (WIP), City of
Control Board • Central Control Board • Central Modesto wells 11, 14, ft
Valley Region Valley Region 21 • soil, gas survey
Victor Izzo Jerry Bruns Memo:.Well investigation
CA Regional Water Quality CA Regional Water Quality City of Modesto wells 11,
Control Board - Central Control Board - Central 14 t 21 - soil survey,
Valley Region Valley Region w/TL to M Gilton fr V
Izzo 8/24/90
AR 30 01 1067
90/08/28 Paul Martin
William Lewis
Memo: Phase 2 results of
-------
Page 4
07/10/97
Modesto Groundwater Contamination
Hodesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR * ROLL * FRAME * DATE AUTHOR ADDRESSEE. SUBJECT
yy/on/dd
Environmental Protection Environmental Protection soil borings t well
Agency • Region 9 Agency • Region 9 sampling for tuiicipal
well 111 site
investigation
AR 31 01 1105 90/09/21 Robert Bernstein Jean Rice Memo: Transmits pages of
Environoental Protection Environmental Protection site assessment, u/attch
Agency - Region 9 Agency • Region 9
AR 32 01 1109 90/09/25 Jeff Zelikson HaIford's Cleaners Administrative order in
Environmental Protection matter of HaIford
Agency - Region 9 Cleaners, et al, docket
WO-19, w/attchs A. B
(field Inves *
tetrachloroethene) * C
(soil boring data)
AR 33 01 1127 90/10/01 Robert Fores Jeff Zelikson Ltr: Inform that S
Glanelli, Brew t MayoI Environmental Protection Jamnadas will comply with
Agency • Region 9 terms of AO 090-19
AR 34 01 1130 90/10/16 Site management plan,
municipal well f11.
w/maps (privileged, FOIA
ex 5}
AR 35 01 1132 90/10/24 Draft site management
plan,.w/maps (privileged,
FOIA ex 5)
AR 36 01 1134 90/10/25 Condor Earth Technologies Environmental Protection Uorkplan for compliance
Agency • Region 9 with AO 090-19, w/TL to J
Clifford fr R Fores
10/26/90
AR 37 01 1142 90/11/02 Robert Bornstein Robert Fores Ltr: Review of proposed
Environmental Protection Gianelll, Brew t MayoI workplan prepared by
Agency - Region 9 Condor Earth Technologies
-------
Page 5
07/10/97
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR *
ROLL * FRAME *
DATE
yy/im/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 40
01
1181 90/12/03
Environmental Protection
Agency - Region 9
Robert Fores
Gianelll, Brew A KayoI
Dufour I Scharff
Jean Rice
Environmental Protection
Agency - Region 9
delay in receiving health
I safety plan, AO f90-19
Transacts health,
safety A environmental
protection policy,
w/attch
AR 41
01
1202 90/12/05
Robert Bornstein
Environmental Protection
Agency - Region 9
Robert Fores
Gfanelll, Brew & Mayo I
Ltr: Proposed health I
safety plan prepared by
Condor Earth Technologies
(GET) on 12/3/90, AO f90-
19
AR 42
OT
1205 90/12/10
AR 43
AR 44
01
01
1207 90/12/10
1209 90/12/10
Clifford Davis
Environmental Protection
Agency - Region 9
Clifford Davis
Environmental Protection
Agency - Region 9
Robert Bornstein
Environmental Protection
Agency - Region 9
John Lucey
Environmental Protection
Agency - Region 9
John Lucey
Environmental Protection
Agency • Region 9
Russel Tonda
HaIford's Cleaners
Mem: Baseline PRP search
rpt, w/di rectory, susaery
sheets, PRPs, ROCs, data
displays, notes, trip
rpt, permit t RPM note
book (privileged, FOIA ex
5)
Mean: Baseline PRP rpt
(privileged, FOIA ex 5)
Ltr: Follow-up to
10/25/90 Itr pursuant AO
#90-19, to begin taking
action to contain t
•itigate soil
contamination
AR 45
01
1211 90/12/10
Robert Bornstein
Environmental Protection
Agency - Region 9
Susan Lyons
Conklln Bros
Ltr: Follow-up to
10/25/90 Itr pursuant AO
*90-19, to begin taking
action to contain i
mitigate soil
contamination
AR 46
01
1213 90/12/10
AR 47
01
1215 90/12/10
Robert Bornstein
Environmental Protection
Agency - Region 9
Robert Bornstein
Environmental Protection
Agency - Region 9
Steve Lyons
Conklin Bros
Shantllal Jamnadas
HaI ford's Cleaners
Ltr: Follow-up to
10/25/90' Itr pursuant AO
*90-19, to begin taking
action to contain I
mitigate soil
contamination
Ltr: Follow-up to
10/25/90 Itr pursuant AO
*90-19, to begin taking
-------
Page 6
07/10/97
Modesto Grounduater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
Aft NUMBER ORDER
AR « ROLL * FRAME * DATE
yy/nn/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 48 01 1217 90/12/10 Robert Bornstein Diane Tonda
Environmental Protection HaIford's Cleaners
Agency • Region 9
AR 49 01 1220 91/00/00 CA Regional Water Quality
Control Board
AR SO 01 1269 91/00/00 Jerry Clifford Steven Lyon
Environmental Protection Conklin Bros
Agency - Region 9
AR 51 01 1272 91/00/00 Jerry Clifford Susan Lyon
Environmental Protection Conklin Bros
Agency - Region 9
AR 52 01 1275 91/00/00 Jerry Clifford Russell Tonda
Environmental Protection HaI ford's Cleaners
Agency • Region 9
AR 53 01 1278 91/00/00 Jerry Clifford Diane Tonda
Environmental Protection Halford's Cleaners
Agency - Region 9
AR 54 01 1281 91/01/00
AR 55 01 1439 91/01/02 Robert Fores Steve Lyon, Russ Tonda
Glanelli, Brew & MayoI Conklin Bros
AR 56 01 1442 91/01/02 Robert Bornstein Russel Tonda
Environmental Protection Halford's Cleaners
Agency - Region 9
action to contain &
mitigate soil
contamination
Ltr: Follow-up to
10/25/90 Itr pursuant AO
f90-19, to begin taking
action to contain &
mitigate soil
contamination
Possible source of PCE
contamination in Modesto
drinking water wells.
w/attchs
Ltr: 104(e) request for
information, w/mail
receipt fP347537149
Ltr: 104(e) request for
information, w/o mail
receipt 0P347537150
Ltr: General
notice/104(e) request
Information, w/o mail
receipt fP347537151
for
Ltr: General
notlce/104(e> request for
information, w/o mail
receipt fP3475371S2
Staff rpt, cleanup t
abatement order for PCE
dischargers in Turlock,
w/maps
Ltr: Request to set
meeting re cleanup of
soil contamination at
HaIford
Ltr: Follow-up to 1/21/91
extension pursuant AO
*90-19, to begin
implementing effective
treatment system to
remove organic solvent
-------
Page 7
07/10/97
Modesto Groundwater contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR *
ROLL # FRAME *
DATE
yy/on/dd
AUTHOR
ADDRESSEE
SUBJECT
contamination
AR 57 01
1444 91/01/02
Robert Bornstein
Environmental Protection
Agency - Region 9
Shentilal Jarmadas
HaIford's Cleaners
Ltr: Follow-up to 1/21/91
extension pursuant AO
#90-19, to begin
implementing effective
treatment system to
remove organic solvent
contamination
AR 58 01
1446 91/01/02
Robert Bornstein
Environmental Protection
Agency - Region 9
Susan Lyons
Conklin Bros
Ltr: Follow-up to 1/21/91
extension pursuant AO
•90-19, to begin
implementing effective
treatment system to
remove organic solvent
contamination
AR 59 01
1448 91/01/02
Robert Bornstein
Environmental Protection
Agency - Region 9
Steve Lyons
Conklin Bros
AR 60 01
1450 91/01/02
Robert Bornstein
Environmental Protection
Agency - Region 9
AR 61 01
1452 91/01/17
Robert- Fores
Gianellt, Brew ft Mayo I
Diane Tonda
Halford's Cleaners
Robert Bornstein, Jean
Rice
Environmental Protection
Agency - Region 9
Ltr: Follow-up to 1/21/91
extension pursuant AO
#90-19, to begin
implementing effective
treatment system to
remove organic solvent
contamination
Ltr: Follow-up to 1/21/91
extension pursuant AO
#90-19, to begin
implementing effective
treatment system to
remove organic solvent
contamination
Ltr: Confirms that
Halford Cleaners
representative met with R
Tonda ft S Lynos re work
required by EPA, AO #90-
19
AR 62 01
AR 63 01
1456 91/01/28. Robert Bornstein
Environmental Protection
Agency - Region 9
1458 91/02/07
Robert Bornstein
Environmental Protection
Agency - Region 9
Russel Tonda
Halford's Cleaners
Russel Tonda
Halford's Cleaners
Ltr: Review of workplan &
health I safety plan
submitted by ACC on
1/24/91, AO order #90-19
Ltr: Receiving work
schedule submitted by
ACC, 2/5/91, removal
order #90-19
-------
Page 8
07/10/97
Modesto Grounduater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR f ROLL * FRAME * DATE
yy/nn/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 64
AR 65
AR 66
AR 67
AR 68
AR 69
AR 70
AR 71
Aft 72
AR 73
AR 74
01
01
01
01
01
01
01
01
1460 91/02/20
1463 91/03/20
1492 91/04/09
1495 91/04/09
1498 91/04/29
1505 91/04/30
1507 91/05/08
1509 91/05/13
Robert Bornstein
Environmental Protection
Agency - Region 9
Modesto Interagency
Committee
01
01
01
Jerry Clifford
Environmental Protection
Agency - Region 9
Jerry Clifford
Environmental Protection
Agency - Region 9
Environmental Protection
Agency • Region 9
John Lucey
Environmental Protection
Agency - Region 9
Doug Frazer
Environmental Protection
Agency - Region 9
Shentilal Jamnadas
HaIford's Cleaners
Shentilal Jamnadas
Halford's Cleaners
Interagency Members
Memo: Initiation of work
at Hat ford Cleaners
pursuant to EPA removal
order 090-19, u/map
Statement of work (SOU),
phase 1 RI, w/amendment
f 1 t 2
Ltr: General
notice/104(e) request for
information, w/o mail
receipt «P3475371S4
Ltr: 104(e) request for
information, w/o mail
receipt *P347537153
EPA review Garments on
EtE draft workplan
Memo: Interagency review
of draft project plans
John Lucey '
Environmental Protection
Agency • Region 9
Philip Isorena John Lucey
CA Regional Water Quality Environmental Protection
Control Board ' Agency - Region 9
1513 91/05/16
1525 91/05/22
1527 91/05/23
Emmanuel Mensah
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
John Lucey
Environmental Protection
Agency • Region 9
Victoria Taylor
I C F Technology, Inc
John Lucey
Environmental Protection
Agency • Region 9
Interagency Members
John Lucey
Environmental Protection
Agency - Region 9
Memo: Comments on phase 1
workplan - revision 0
Ltr: Connents on phase 1
RI workplan, sampling ft
analysis plan (SAP) I
quality assurance project
plan (QAPP)
Ltr: Review of draft
project plans for well
f11. w/attch
Memo: Interagency review
of draft sampling I
analysis plan (SAP)
Memo: Connents on draft
workplan & quality
assurance project plan
(QAPP) for phase 1 RI
-------
Page 9
07/10/97
AR *
ROLL » FRAME *
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
DATE
yy/nn/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 75
AR 76
AR 77
AR 78
AR 79
01
01
01
01
01
1530 91/05/28 Jerry Clifford
Environmental Protection
Agency - Region 9
1541 91/05/28
1552 91/05/28
Jerry Clifford
Environmental Protection
Agency - Region 9
Jerry Clifford
Environmental Protection
Agency • Region 9
1563 91/05/28 Jerry Clifford
Environmental Protection
Agency - Region 9
1573 91/05/30
AR 80
01
1581 91/06/04
John Lucey
Environmental Protection
Agency • Region 9
Philip Isorena
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
Lynn Stinson
Stinson-Heath Mazda
Bill Edwards
Parts House 3
Jack Hart
HaIford's Cleaners
Adam Hart
HaI ford's Cleaners
Cheryl Robinson
Ecology ft Environment,
Inc
John Lucey
Environmental Protection
Agency - Region 9
Ltr: 104(e) request for
information, u/attch A ft
mail receipt *P347509976
Ltrr 104(e) Itr of
request, w/mail receipt
#P347509977
Ltr: General
notice/104(e) request
information, w/mail
receipt *P347509979
for
Ltr: General
notice/104(e) request for
information, w/mail
receipt *P347509978
Mean: Transaits EPA
review comments on draft
quality assurance project
plan (QAPP) & health ft
safety plan (HSP) for
phase 1 RI, u/attch
Ltr: Comments on sampling
4 analysis plan (SAP),
phase 1 RI
AR 81
AR 82
AR 83
AR 84
AR 85
01
01
01
01
01
1586 91/06/12
1589 91/06/12 Sripriya Chari
I C F Technology, Inc
Site description ft
1592 91/06/14
John Lucey
•Environmental Protection
Agency - Region 9
1604 91/06/19 Robert intner
1611 91/06/25
Bill Edwards
Parts House 3
John Lucey
•Environmental Protection
Agency - Region 9
Cheryl Robinson
Ecology ft Environment,
Inc
Clifford Davis
Environmental Protection
Agency - Region 9
Jerry Clifford
Environmental Protection
Memo: Comments on draft
workplan for phase 1 RI
Memo: Transmits EPA
review comments on draft
field sampling plan
Itr of request re Adam &
Jack Hart, w/o mail
receipt 0P805772990
Response to 104(e) Itr of
request, financial
-------
Page 10
07/10/97
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR *
ROLL * FRAME f
DATE
yy/nm/dd
AUTHOR
ADDRESSEE
SUBJECT
Agency - Region 9
AR 86
AR 07
AR 88
AR 89
AR 90
AR 91
AR 92
AR 93
AR 94
01
01
01
01
01
01
01
01
01
1708
1712
1716
information, w/attchs
(privileged, FOIA ex 4)
1613 91/07/10
1675 91/07/10
Ecology I Environment,
Inc
Chris Lichens
Ecology I Environment,
Inc
Environmental Protection Final draft health I
Agency - Region 9 safety plan (HSP), phase
1 RI
1679 91/07/10 Chris Lichens
Ecology & Environment,
Inc
1684 91/07/12
1696 91/07/15
Chris Lichens
Ecology I Environment,
Inc
John Lucey
Environmental Protection
Agency - Region 9
John Lucey
Environmental Protection
Agency - Region 9
John Lucey
Environmental Protection
Agency - Region 9
Philip Isorena Hal Slnidian
CA Regional Water Quality Modesto Steam Laundry &
Control Board • Central Cleaners
Valley Region
Mean: Response to EPA
connents on phase 1 Rt
final draft workplan
Mean: Response to
connents on draft quality
assurance project plan
(QAPP) ft health ft safety
plan (HSP)
Mean: Response to EPA ft
ESAT connents on phase 1
RI final draft field
sampling plan
Ltr: Transmits analytical
results of reclaimer
uastewater sample taken
during visit of 6/14/91,
w/attch
91/07/23 Victoria Taylor
I C F Technology,
Inc
91/07/25 Victoria Taylor
I C F Technology, Inc
John Lucey
Environmental Protection
Agency - Region 9
John Lucey
Environmental Protection
Agency - Region 9
Comments on final
draft field sanpling plan
(FSP) for phase 1 Rt,
w/attch
Mean: Comments on final
draft quality assurance
project plan (QAPP) for
phase 1 RI, w/attch
91/08/01 Doug Frazer John Lucey Mean: Comments on final
Environmental Protection Environmental Protection workplan for phase 1 RI
Agency • Region 9 Agency - Region 9
1719 91/08/06
Robert Intner
Law Office of Robert J
Intner
Clifford Davis
Environmental Protection
Agency - Region 9
Ltr: Response to 104(e)
request re Jack & Adam
Hart, w/financial
statements & property
sale contract
(privileged, FOIA ex 5)
AR 95
01
1721 91/08/08 Victoria Taylor
John Lucey
Memo: Comments on final
-------
Page 11
07/10/97
Modesto Groindwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR f ROLL * FRAME f DATE AUTHOR ADDRESSEE SUBJECT
yy/iw/dd
I C F Technology, Inc Environmental Protection draft field ft coupling
Agency • Region 9 plan (FSP) for phase t
RI, w/connents on revised
final draft quality
assurance project plan
(QAPP)
AR 96 01 1724 91/08/19 Ecology ft Environment, Environmental Protection Uorkplan, phase 1 RI
Inc Agency • Region 9
AR 97 01 1771 91/08/19 Ecology ft Environment, Environmental Protection Field sampling plan,
Inc Agency • Region 9 phase 1 RI
AR 98 01 1902 91/08/19 Ecology ft Environment, Environmental Protection RI/FS, quality assurance
Inc Agency - Region 9 project plan (QAPP),
phase 1
AR 99 01 1971 91/08/19 Chris Lichens John Lucey Mew: Revisions to final
Ecology t Environment, Environmental Protection draft workplan, field
Inc Agency - Region 9 caopling plan (FSP) ft
quality assurance project
plan (QAPP) for phase 1
RI, w/attch
AR 100 01 1975 91/09/03 John Lucey Michael Cilton Ltr: Uorkplan. FSP, QAPP
Environmental Protection City of Modesto ft HSP for phase 1 RI, M/O
Agency - Region 9 ends
AR 101 01 1977 91/09/03 John Lucey Philip Isorena Ltr: Workplan, FSP. QAPP
Environmental Protection CA Regional Water Quality t HSP for phase 1 RI, u/o
Agency • Region 9 Control Board ends
AR 102 01 1979 91/09/03 John Lucey Enunuel Meraah Ltr: Uorkplan. FSP, QAPP
Environmental Protection CA Oept of Health ft HSP for phase 1 RI, u/o
Agency - Region 9 Services ends
AR 103 01 1981 91/09/03 John Lucey Robert Fourt Ltr: Uorkplan, FSP, QAPP
Environmental Protection Stanislaus County - Oept ft HSP for phase 1 RI, u/o
Agency • Region 9 of Environmental ends
Resources
AR 104 01 1983 91/09/04 Ecology ft Environment, Environmental Protection Health 4-safety plan
Inc Agency - Region 9 (HSP), phase 1 RI
AR 105 01 2046 91/09/Z4 Ron Franz John Lucey Ltr: Response to 9/3/91
City of Modesto Environmental Protection Itr re disposal of
Agency - Region 9 Monitoring well
production water at Water
Quality Control Plant at
1221 Suiter Ave, w/ltr of
-------
Page 12
07/10/97
Modesto Groinduater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR HUKBER ORDER
AR *
ROLL * FRAME *
DATE
yy/nm/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 106
01
2051 91/10/01
Philip Isorena
CA Envirornentat '
Protection Agency - Dept
of Toxic substances
Control
John Lucey
Environmental Protection
Agency - Region 9
9/19/91
Ltr: Comments on final
plans for phase 1 RI/FS
AR 107
01
2056 91/10/30
AR 108
AR 109
01
01
2059 91/11/12
2062 91/11/12
John Lucey
Environmental Protection
Agency - Region 9
Robert Bornstein
Environmental Protection
Agency - Region 9
John Lucey
Environmental Protection
Agency - Region 9
Michael Gilton
City of Modesto
Modesto Interagency
Committee
Ltr: EPA plans to conduct
aquifer pump test at well
#11 to obtain
hydrogeologic information
in vicinity of well
Memo: Transmits PID
sampling results at
Halford Cleaners, w/attch
Philip Isorena Ltr: Follow-up to
CA Regional Water Quality telephone conversation on
Control Board 9/26/91 re contents on
FSP t QAPP
AR 110
01
2066 91/11/12
John Lucey
Environmental Protection
Agency - Region 9
Philip Isorena Ltr: Discussion of
CA Regional Water Quality comnents received 10/1/91
Control Board re final phase 1 Rl
workplan, field saopling
plan (FSP) A quality
assurance project plan
COAPP)
AR 111
01
2070 91/12/05
AR 112
AR 113
AR 1U
01
01
01
2076 91/12/16
2078 92/00/00
Robert Bornstein
Environmental Protection
Agency - Region 9
Dave McCain
McCain Environmental
Services
Modesto Interagency
Committee
Robert Bornstein
Environmental Protection
Agency • Region 9
2080
Memo: Operation of soil
vapor extraction system
(SVE) at Halford, w/memo
of 11/26/91, lab rpt t
chain of custody
Moao: Operation of soil
vapor extraction system
at Halford Cleaners
Package' containing
docunents re removal
action (privileged, FOIA
ex 4)
92/01/07 Philip Isorena Wendy Cohen Memo: Modesto well
CA Regional Water Quality CA Regional Water Quality investigation summary,
Control Board - Central Control Board - Central w/TL to D Hoi ton fr W
Valley Region Valley Region Cohen 1/7/92, w/maps
-------
Page 13
07/10/97
AR «
ROLL * FRAME *
DATE
yy/nw/dd
Modesto Groindwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AUTHOR
ADDRESSEE
SUBJECT
AR 115
01
AR 116
AR 117
01
01
AR 118
01
AR 119
AR 120
AR 121
AR 122
01
01
01
01
2100 92/01/13 Clifford Davis
Environmental Protection
Agency * Region 9
2102 92/03/00 Environmental Protection
Agency - Region 9
2107 92/03/02 Robert Fourt
Stanislaus County - Dept
of Environmental
Resources
2116 92/03/04 Randa Bishlawi
Environmental Protection
Agency. - Region 9
2122 92/03/09 George Broun
Geological Technics, Inc
216? 92/03/09 Michael Milich
City of Modesto
2188 92/03/11 Chris Lichens
Ecology A Environment,
Inc
2190 92/03/18 Chris Lichens
Ecology & Environment,
Inc
AR 123 01
AR 124 01
2192 92/03/30
Michael Gilton
City of Modesto
John Lucey
Environmental Protection
Agency - Region 9
Michael Milich
City of Modesto
Robert Fourt
Stanislaus County • Dept
of Environmental
Resources
Randa Bishlaui
Environmental Protection
Agency - Region 9
John Lucey
Environmental Protection
Agency - Region 9
Alan Cozby
City of Modesto • Water
Dept
John Lucey
Environmental Protection
Agency - Region 9
2205 92/04/24 Keith Takata Friederich Von Eichel-
Envlronmental Protection Streiber Frlede
Trip rpt of 1/9/92 to
Modesto to perform tasks
re ownership I business
activities at property at
931 McHenry Ave
(privileged, FOIA ex 5}
Fact sheet: Investigation
of groundwater
contamination begins
Memo: Transmits uell
boring logs, generalized
site.plans A cross
sections for Unocal bulk
plant #438, u/attchs
Ltr: 104(e) request for
inforation re video
inspection of sewer
line*, w/TL 3/4/92 ft
message confirmation
Mean: Transmits data
requested re Deet Eichle
or Chuck Hillery
properties, w/attch
Ltr: Response to 104(e)
Itr of request re video
inspection of sewer lines
Mean: Task 4.2 costs,
u/sumnry of cost budget
Increase for WAF
(privileged, FOIA ex 4)
Ltr: Conducting aquifer
pump test to determine
radius of influence t
characteristics of
aquifer-underling area
around veil #11
Ltr: Transmits well water
analysis for wells #2,
11, 14, 17 ft 21, w/attch
Ltr: General
notice/104(e) request for
-------
Page U
07/10/97
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR * ROLL * FRAME * DATE AUTHOR ADDRESSEE SUBJECT
yy/sn/dd
Agency - Region 9 R Lewie • U Rea A Co information, w/o nil
receipt «P686926482,
u/attch A
AR 125 01 2215 92/05/H Roland Stevens Randa Bichlawi Ltr: Sleeving Hal fords
City of Modesto Environmental Protection sewer line
Agency - Region 9
AR 126 01 2217 92/05/19 Randa Bishlawi Michael Nillch. Roland Ltr: 104 request for
Environmental Protection Stevens information re video
Agency • Region 9 City of Modesto inspection of sewer
lines, w/TL 5/19/92 ft
confirmation
AR 127 01 2222 92/05/21 Roland Stevens Randa Bishlawi Ltr: Response to 104(e)
City of Modesto Environmental Protection Itr of request re
Agency • Region 9 videotape inspection of
•ewer lines
AR 128 01 2224 92/05/27 Lynne Baungras Robert Fourt Ltr: Permission to
Ecology £ Environment, Stanislaus County • Oept dispose of drill cuttings
Inc of Environmental I investigation-derived
Resources residuals, w/analytical
testing on soil £
composite samples
AR 129 01 2228 92/08/00 Ecology t Environment, Environmental Protection Community relations plan
Inc Agency - Region 9
AR 130 01 2264 92/09/01 John Lucey Michael Gil ton Ltr: Recently discovered
Environmental Protection City of Modesto water supply well was
Agency - Region 9 formerly used by private
water company located at
505 McNenry Ave in
Modesto
AR 131 01 2266 92/10/07 Chris Lichens John Lucey Memo: Specific
Ecology t Environment, Environmental Protection recomnendation for
Inc Agency - Region 9 additional site
characterization
AR 132 01 2269 92/11/19 Keith Takate Steven Lyon A Susan Lyon Ltr: 104(e) request for
Environmental Protection Conklin Bros • information, w/mall
Agency - Region 9 receipt 0P424453333
AR 133 01 2273 92/11/19 Keith Takata Russell Tonda t Diane Ltr: 10<(e) request for
Environmental Protection Tonda information, w/mail
Agency • Region 9 HaI ford's Cleaners receipt 0P686926S58
AR 134 01 2278 92/11/19 Keith Takata Friederich Von Eichel- Ltr: 10A(e> request for
-------
Page 15
07/10/97
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR * ROLL * FRAME * DATE AUTHOR ADDRESSEE SUBJECT
yy/im/dd
Envlroraental Protection Streiber information, u/nail
Agency • Region 9 R Lewis - U Rea ft Co receipt fP424453332
AR 135 01 2281 92/12/09 CA Environmental Dom Diebert Memo: Review of final
Protection Agency • Dept CA Environmental draft RI rpt, w/maps
of Toxic Substances Protection Agency - Dept
Control of Toxic Substances
Control
AR 136 01 2286 92/12/09 Dom Diebert Greg Baker Ltr: Review of final
CA Environmental Environmental Protection draft RI rpt
Protection Agency - Dept Agency - Region 9
of Toxic substances
Control
AR 137 01 2288 93/01/22 Roray Angle John Lucey Ltr: Response to general
R Lewis - W Rea ft Co Environmental Protection - notice/104
-------
Page 16
07/10/97
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR
ROLL * FRAME *
DATE
yy/om/dd
AUTHOR
ADDRESSEE
SUBJECT
of Toxic Substances
Control
AR 145
AR 146
AR 147
AR 148
01
01
01
01
2469 93/04/01
2475 93/04/01
John Lucey
Environmental Protection
Agency • Region 9
John Lucey
Environmental Protection
Agency » Region 9
Russell Tonda ft Dia
Tonda
Halford's Cleaners
Shantilal Jannadas
Halford's Cleaners
Ltr: 104(e) request for
Information, w/mail
receipt KP424454712
Ltr: General
nottce/104(e) request
information,, w/mail
receipt *P424454711
for
2479 93/04/01 John Lucey Steven Lyon ft Susan Lyon Ltr: 104(e) request for
Environmental Protection Conk I in Bros Information, it/mail
Agency • Region 9 receipt 4P424454713
2485 93/04/06
AR 149
AR 150
AR 151
AR 152
AR 153
01
01
01
01
01
2517 93/04/12
2519 93/04/15
2521 93/04/15
2527 93/05/12
2529 93/05/14
Shantilal Jamnada
Halford's Cleaners
John Lucey
Environmental Protection
Agency • Region 9
Steven Lyon
Steven
Conklln Bros
Steven Lyon
Conklin Bros
Alice Tulloch
City of Modesto
Emenuel Mensah
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
John Lucey
Environmental Protection
Agency - Region 9
Alice Tulloch
City of Modesto
John Lucey
Environmental Protection
Agency • Region 9
John Lucey
Environmental Protection
Agency - Region 9
John Lucey
Environmental Protection
Agency - Region 9
John Lucey
Environmental Protection
Agency - Region 9
Ltr: Response to 104(e)
Itr of request,
w/manifests ft technical
papers, u/o mail receipt
•P157223692
nt of 2
Ltr: Abandonw
private wells
Response to 104(e) Itr re
financial information
(privileged, FOIA ex 4}
Ltr: Response to 104
-------
Page 17
07/10/97
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR *
ROLL * FRAME *
DATE
yy/im/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 155
AR 156
AR 157
AR 158
AR 159
AR 160
AR 161
01
01
01
01
01
01
01
2541 93/06/10 John Lucey Chris Lichens
Environmental Protection Ecology ft Environment,
Agency • Region 9 !nc
25U 93/06/10
2548 93/06/15
2550 93/07/13
2552 93/07/29
John Lucey
Environmental Protection
Agency - Region 9
John Lucey
Environmental Protection
Agency - Region 9
Chris Lichens
Ecology ft Environment,
Inc
John Lucey
Environmental Protection
Agency • Region 9
AR 162
01
AR 163
01
2556 93/08/13 Ecology ft Environment,
Inc
2586 93/08/23 Lynne Baumgras
Ecology ft Environment,
Inc
2590 93/08/23 Lynne Baumgras
Ecology ft Environment,
Inc
2595 93/09/16 Chris Lichens
Ecology ft Environment,
Inc
Chris Lichens
Ecology ft Environment,
Inc
Alice Tulloch
City of Modesto
Christine Beach
Environmental Protection
Agency - Region 9
Chris Lichens
Ecology ft Environment,
Inc
Envirornental Protection
Agency • Region 9
Robert Fourt
Stanislaus County • Dept
of Environmental Health
John Rivera
City of Modesto • Water
Quality Control Facility
John Lucey
Environmental Protection
Agency - Region 9
AR 164 01
2597 93/09/17
CA Regional Water
Pollution Control Board
fS
Memo: Coanents on draft
workplan for phase 2 RI
4/5/93
Technical nemo: Directive
for conducting risk
assessment
Ltr: Abandonment of 2
private wells
Ltr: Coanents on
additional costs ft LOE,
w/o workplan (privileged,
FOIA ex 4)
Memo: Comments on final
draft workplan for phase
2
Workplan, RI phase 2
Ltr: Request for
permission to dispose of
drill cuttings ft soil
cores at Fink Road
Landfill, w/attchs
Ltr: Request for
permission to dispose of
monitoring well
production water in city
sewer, w/attchs
Memo: Workplan for
additional phase 1 RI
funding ft LOE, w/neno #2
(11/6/92) ft nemo «1
(4/5/91) (privileged,
FOIA ex O
Mtg agenda: Meeting of
9/17/93
AR 165 01
2603 93/09/23
John Lucey
Environmental Protection
Agency - Region 9
Emmanuel Mensah
CA Environmental
Protection Agency
Dept
Ltr: update of schedule
activities, info re
proposed plan & FS
-------
Page 18
07/10/97
Modesto Grounduater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR
ROLL * FRAME *
DATE
yy/na/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 166 01
AR 167 01
2606 93/09/28
2609 93/09/28
AR 168
01
26U 93/09/29
John Lueey
Environmental Protection
Agency - Region 9
John Lueey
Environmental Protection
Agency - Region 9
of Toxic Substances
Control
Art Motulewfcz
Art Hotulewicz
Modesto Elks Lodge 11282
David Jones
Environmental Protection
Agency • Region 9
Janes Tjosvold
CA Environmental
Protection Agency • Dept
of Toxic Substances
Control
Ltr: Closure of Elks
Lodge well
Ltr: Request for closure
of contaminated
groundwater well,
w/response Itr to J Lueey
fr A Motulewicz re
agreement to well closure
12/2/93
Ltr: Request for State
ARARs analysis, w/encl
AR 169
01
2626 93/09/29
AR 170
AR 171
AR 172
AR 173
AR 174
01
01
01
01
01
2638 93/10/11
David Jones
Environmental Protection
Agency • Region 9
Chris Lichens
Ecology t Environment,
Inc
JMKS Tjosvold
CA Environmental
Protection Agency • Oept
of Toxic Substances
Control
John Rivera
City of Modesto - Water
Quality Control Facility
2640 93/10/22 CA Regional Uater Quality
Control Board - Central
Valley Region
2644 93/10/28
2814 93/10/28
2892 93/11/04
Ecology * Environment,
Inc
Ecology A Environment,
Inc
Emmanuel Mensah
CA Environmental
Protection Agency • Dept
of Toxic Substances
Control
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
Ltr: Request for State
ARARs analysis, w/attch
Ltr: Request for
permission to dispose of
monitoring well purge
water into city sewer
Ntg agenda: Metting of
10/22/93
RI/FS rpt, quality
assurance project plan
(QAPP), phase 2
Field sampling plan
(FSP), phase 2 RI (final
rev)
Philip Isorena Ltr: Identifying State
CA Regional Water Quality applicable or relevant I
Control Board appropriate requirements
(ARARs)
-------
Page 19
07/10/97
Modesto Grounduater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR * ROLL * FRAME
DATE
yy/mn/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 175 01 2895
AR 176 01 2898
AR 177 01 2901
AR 178 01 2904
AR 179 01 2907
AR 180 01 2909
AR 181 01 2913
93/11/04 Ennanual Mensah
CA Environmental
Protection Agency • Dept
of Toxic Substances
Control
93/11/04 Ennanual Mensah
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
93/11/04 Eoraanual Mensah
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
93/11/04 Ennanual Hensah
CA Environmental
Protection Agency • Dept
of Toxic Substances
Control
93/11/23 Wendy Cohen
CA Regional Water
Pollution Control Board
*5
93/12/27 Jeff Zetlkson
Environmental Protection
Agency • Region 9
94/02/22 Talin Kaloustian, Joel
Greger
M P D S Services, Inc
Jim Simpson
Stanislaus County - Dept
of Environmental
Resources
John Mayer
City of Modesto
Mark Schonhoff
Stani•I BUS County
Harvey Collins
CA Dept of Health
Services
Eonanual Mensah
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
AR 182 01 2927 94/03/11 I C F Technology, Inc
Penny Silzer
Union Oil Co of
California
Environmental Protection
Agency • Region 9
AR 183 01 2932
94/04/13 William Crooks Addressee
CA Regional Water Quality
Ltr: Identifying State
applicable or relevant C
appropriate requirements
(ARARs)
Ltr: Identifying State
applicable or relevant ft
appropriate requirements
(ARARs)
Ltr: Identifying State
applicable or relevant t
appropriate requirements
(ARARs)
Ltr: Identifying State
applicable or relevant I
appropriate requirements
(ARARs)
Nemo: Water board
applicable or relevant &
appropriate requirments
(ARARs), w/o attch
Policy on shared
financing for remedial
projects involving public
water supply use of
treated groundwater
(unsigned)
Ltr: Quarterly data rpt
re former Unocal Bulk
plant 00438, w/TL to
Stanislaus County fr D
Harding 3/10/94. w/maps &
attchs
Case narrative - volatile
organics analysis (VOA)
of water sample 0SYA431
Ltr: Transmits notice of
public hearing, draft
-------
Page 20
07/10/97
Modesto Grounduater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR *
ROLL f FRAME *
DATE
yy/wi/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 184 01
2941 94/04/25
AR 185 01
2979 94/04/25
AR 186 01
AR 187 01
AR 188 01
AR 189 01
3030
Control Board • Central
Valley Region
Doon Diebert
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
Dam Diebert
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
Dom Diebert
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
94/05/00 Ecology A Environment,
Inc
3017 94/04/29
3094 94/05/02
3097 94/05/17
CA Environmental
Protection Agency • Dept
of Toxic Substances
Control
Kent Kitchingman
Environmental Protection
Agency - Region 9
Kent Kitchingman
Environmental Protection
Agency - Region 9
Kent Kitchingman
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
Environmental Protection
Agency • Region 9
settlement agreements.
cleanup/abatement order t
PCE pollution in
Turlock/Stanislaus
County, w/nap
Ltr: Transmits applicable
or relevant t, appropriate
requirements (ARARs),
w/attch
Ltr: Applicable or
relevant I appropriate
requirements (ARARs)
Ltr: Review of final
draft FS, u/memo re
cgamuts on FS & TL to J
Lucey fr E Mensah
Baseline human health
risk assessment, w/maps
Agenda for EPA t DTSC
conference call
Draft dispute briefing
document, w/marginalia
AR 190 01
AR 191 01
AR 192 01
3101 94/05/17
Draft dispute briefing
document, w/marginalia
3105
3107
94/05/19 Laurence Pearson John Lucey Notice of public hearing
CA Regional Water Quality Environmental Protection (revised)
Control Board - Central Agency - Region 9
Valley Region
94/05/23 Karen Johnson
Ecology & Environment,
Inc
John Lucey
Environmental Protection
Agency - Region 9
Memo: Groundwater
screening ecological
assessment (EA), w/map &
appendix A (field
photography log sheet)
AR 193 01
3120 94/06/01 Ecology & Environment, Environmental Protection fS rpt, u/maps
-------
Page 21
07/10/97
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR HUMBER ORDER
AR
ROLL * FRAME #
DATE
yy/nn/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 194
01
32H 94/06/06
Inc
David Jones
Environmental Protection
Agency - Region 9
Agency • Region 9
James Tjosvold
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
Ltr: Mutual agreement
between EPA t DTSC to
implement new
technologies
AR 195
AR 196
01
01
3217 94/06/06
3219 94/06/06
Alt 197
AR 198
AR 199
AR 200
01
01
01
01
3222 94/06/10
3279 94/06/14
3281 94/06/28
David Jones
Environmental Protection
Agency - Region 9
Chris Lichens
Ecology A Environment,
Inc
James Tjosvold
CA Environmental
Protection Agency • Dept
of Toxic Substances
Control
John Lucey
Environmental Protection
Agency • Region 9
3294
90/07/03 Irene Murata, Robert
Fores
Gianelli, Brew I Mayol
Environmental Protection
Agency - Region 9
AR 201
00/00/00 Todd Uiedemeier
Parsons Engineering
Science
AR 202
00/00/00 Environmental Protection
Agency - Region 9
Agenda for EPA DTSC
conference call
Ltr: Mutual agreement
between EPA ft DTSC to
inplenent new technology
Memo: Results of phase 2
RI, w/map
Mtg agenda: City of
Modesto groundwater
contamination issues
Compendium of CERCU
response selection
guidance for Modesto
Groundwater Contamination
Ltr: Response to item #17
general notice/104(e)
request for info re
Shantilal Jamnadas dba
Halfords cleaners,
w/insurance info
(privileged, FOIA ex 4)
Article: Overview of
technical protocol for
natural attenuation of
chlorinated aliphatic
hydrocarbons in
groundwater, w/TL header
fr E&E 3/28/97
Brief suimary of site
history
AR 203 i/\ bt t\d,4.(~ 00/10/10 Henry Longest
Environmental Protection Memo: Suggested ROD
-------
Page 22
07/10/97
AR *
ROLL * FRAME *
DATE
yy/mn/dd
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AUTHOR
ADDRESSEE
SUBJECT
Environmental Protection Agency
Agency - Washington, D C
language for various
groundwater remediation
options
AR 204
AR 205
AR 206
AR 207
85/04/02 Van Suttzer Mike Kloberdanz Ltr: Transmits data for
City of Modesto - Dept of Stanislaus County • Dept samples taken from Welts
Utility Services of Environmental Health 2 I 11, w/attchs
85/04/02 Van Switier Mike Kloberdanz Ltr: Requests assistance
City of Modesto - Dept of Stanislaus County * Dept in follow-up testing on
Utility Services of Environmental Health A8 1803 Study re wells *2
t *11, w/attchs
AR 208
AR 209
AR 210
AR 211
AR 212
85/10/31 California Water
Laboratories, Inc
86/08/11 Gall Wax Robert Grioshaw
City of Modesto - Oept.of CA Oept of Health
Utility Services Services - Sanitary
Engineering Branch
90/00/00 A C C Environmental
Consultants, Inc
90/00/00 Agriculture ft Priority
Pollutants Labs, Inc
90/00/00 City of Modesto - Fire
Dept
90/03/01 City of Modesto - Dept of
Utility Services
AR 213
90/03/07 Ecology t Environment,
Inc
90/04/00 Environmental Protection
Agency - Office of
Emergency & Remedial
Response
Environmental Protection
Agency - Region 9
Saspling results A chain
of custody record for
samples collected
10/31/85
Ltr: Transmits test
results for well #14
indicating presence of
tetrachloroethene (PCE)
contamination, w/o encl
Workplan A site safety
plan for cleanup at
Halford's Cleaners. w/TLs
Radioactivity * organic
chemical analyses for
Well 11
Modesto Fire Oept Permit
01259 for Halford's
Cleaners
Primary water analysis
for sampling at wells 11
thru 14
Proposed workplan for
Modesto municipal well
f 11 site assessment
project (Redacted, FOtA
exs 4 I 5)
Fact sheet: Guide to
selecting Superfund
remedial actions
-------
Page 23
07/10/97
AR *
ROLL * FRAME *
DATE
yy/m/dd
Hodesto Groundwater Contamination
Modesto. California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AUTHOR
ADDRESSEE
SUBJECT
AR 214
AR 215
AR 216
AR 217
AR 218
AR 219
AR 220
90/05/00 Environmental Protection
Agency - Office of
Emergency I Remedial
Response
90/05/07 Ecology & Environment,
Inc
Dan Shane
Environmental Protection
Agency - Region 9
90/07/00 Environmental Protection
Agency - Office of
Emergency & Remedial
Response
90/08/00 City of Modesto • Dept of
Utility Services
90/10/25 Condor Earth Technologies
AR 221
AR 222
AR 223
AR 224
90/11/02 Robert Bomstein
Environmental Protection
Agency - Region 9
91/00/00 A C C Environmental
Consultants, Inc
91/00/00 A C C Environmental
Consultants, Inc
91/03/29 Robert Bomstein
Environmental Protection
Agency - Region 9
91/04/00 Environmental Protection
Agency - Office of
Emergency t Remedial
Response
91/04/04 Steven Wolfe
Ecology & Environment,
Inc
Robert Fores
Gianelli, Brew t MayoI
Modesto Interagency
Comrittee
Robert Bomstein
Environmental Protection
Agency • Region 9
Fact sheet: Guide to
developing Superfund
proposed plans
Mono: Presents proposed
workplan for remainder of
Modesto Municipal Uell 11
site assessment project
Fact sheet: ARARs Os I
As, state grounduater
antidegradation issues
List of wells out of
service, 8/90
Uorkplan for compliance
with EPA Order 90-19,
H/TL fr ft Fores to J
Clifford 10/26/90
Ltr: Approves 10/26/90
proposed workplan
Supplemental workplan to
address residual PCE soil
contamination I potential
sewer line replacement,
u/TLs
Remediation workplan,
w/TL fr S Wolfe to J
Lucsy 5/22/91
Mean: Transmits 4
documents re Halford's
Cleaners removal action,
w/o encls
/
Fact sheet: Guide to
developing Superfund no
action, interim action &
contingency remedy RODS
Ltr: Notice of intent to
conduct borings to assess
condition of sewer
-------
Page 24
07/10/97
Modesto Croundmter Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR *
ROLL * FRAME *
DATE
yy/nn/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 225
AR 226
AR 227
AR 228
AR 229
AR 230
AR 231
AR 232
AR 233
AR 234
91/04/08 Robert Bornstein
Environmental Protection
Agency - Region 9
Modesto Interagency
Connittee
Hemo: Notice of intent to
conduct borings to assess
condition of sewer
91/04/29 Robert Fourt Robert Bornstein Ltr: Cements on proposed
Stanislaus County - Dept Environmental Protection workplan for soil
of Environmental Agency • Region 9 remediation, u/env
Resources
91/04/29
91/OS/01
91/05/01
91/05/06
91/05/06
Robert Fcurt
Stanislaus County - Oept
of Environmental
Resources
Steven Wolfe
Ecology t Environment,
Inc
Steven Wolfe
Ecology & Environment,
Inc
Robert Bornstein
Environmental Protection
Agency • Region 9
Robert Bornstein
Environmental Protection
Agency - Region 9
Robert Bornstein
Environmental Protection
Agency - Region 9
Philip Isorena Robert Bornstein
CA Regional Water Quality Environmental Protection
Control Board - Central Agency • Region 9
Valley Region
Eonsnucl Nensah
CA Environmental
Protection Agency - Oept
of Toxic Substances
Control
Robert Bornstein
Environmental Protection
Agency - Region 9
91/05/06
Philip Isorena Robert Bornstein
CA Regional Water Quality Environmental Protection
Control Board - Central Agency • Region 9
Valley Region
91/05/07 Robert Bornstein Modesto Interagency
Environmental Protection Connittee
Agency • Region 9
91/05/09 Robert Bornstein
Environmental Protection
Agency - Region 9
Steve Wolfe
A C C Environmental
Consultants, Inc
Ltr: Coanents on workplan
for soil remediation at
HaIford's Cleaners
Ltr: Transmits results fr
soil borings & sanpling
performed at HaIford
Cleaners, w/encl
Ltr: Transmits results fr
soil borings to assess
condition of sewer
Ltr: Coanents on proposed
workplan for soil
remediation
Ltr: No comments on
workplan for cleanup of
soil
Ltr: Cements on workplan
for remaining work at •
HaIford Cleaners
Mean: Transmits results
fr soil borings t
sanpling performed at
HaIford Cleaners, w/o
encl
Ltr: Garments on workplan
I sewer boring results
AR 235
91/06/20 Robert Bornstein
Jim Jacobs
Ltr: Concerns over delay
-------
Page 25
07/10/97
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR * ROLL # FRAME
DATE
yy/mm/dd
AUTHOR
ADDRESSEE
SUBJECT
Environmental Protection
Agency - Region 9
A C C Environmental
Consultants, Inc
AR 236
AR 237
AR 238
91/06/21
91/06/24
Philip Isorena Steven Wolfe
CA Regional Water Quality A C C Environmental
Control Board - Central Consultants, Inc
Valley Region
Robert Bernstein
Environmental Protection
Agency - Region 9
Tony Mendes
Stanislaus County • Air
Resource Board
in Implementing soil
vapor extraction system
Ltr: Comments on final
workplan for soil
remediation at HaIford
Cleaners, w/attchs
Ltr: Request for approval
of air permits as quickly
as possible
91/07/01 Robert Bornstein Philip Isorena Ltr: Requests support for
Environmental Protection CA Regional Water Quality source control actions at
Agency - Region 9 Control Board - Central HaIford Cleaners under
Valley Region Administrative Order 90-
19
AR 239
AR 240
AR 241
AR 242
AR 243
91/07/30 Robert Bornstein
Environmental Protection
Agency - Region 9
91/09/25 Ecology t Environment,
Inc
91/11/10 Dave McCain
McCain Environmental
Services
91/11/18 Joe Spano
CA Oept of Health
Services - Office of
Drinking Water
91/11/21 Robert Bornstein
Environmental Protection
Agency - Region 9
Modesto Interagency
Committee
Robert Bornstein
Environmental Protection
Agency - Region 9
John Lucey
Environmental Protection
Agency - Region 9
Steve Lyons
Conklin Bros
Memo: Sunmary of 7/25/97
mtg to discuss operation
of coil vapor extraction
system
Soil gas data sheets for
8/30 - 9/25/91
Ltr: Notification of
results of air monitoring
of vapor extraction
system at Halford
Cleaners, 10/18/91-
11/8/91
Mean: Transmits chemical
contamination tracking
sheets for wells 11, 14,
17, I 21 (handwritten),
w/attchs
Ltr: Requests PIO testing
data be received on
weekly basis, also
requests plan & schedule
for disposal and/or
treatment of drums behind
cleaners
AR 244
91/11/26 Dave McCain
McCain Environmental
Services
Robert Bornstein
Environmental Protection
Agency - Region 9
Ltr: Transmits results of
air sampling analysis
taken fr vapor extraction
-------
Page 26
07/10/97
Modesto Grounduater Contamination
Modesto. California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR
ROLL 0 FRAME *
DATE
yy/om/dd
AUTHOR
ADDRESSEE
SUBJECT
system at HaIford
Cleaners on 12/23/91
AR 245
91/12/06 Mary Hart
I C F Technology, Inc
Environmental Protection- Data validation rpt: Case
Agency • Region 9
AR 246
91/12/06 Rameen Moezzi
I C F Technology, Inc
Environmental Protection
Agency - Region 9
AR 247
91/12/09 Mary Hart
I C F Technology, Inc
Environmental Protection
Agency - Region 9
AR 248
91/12/10 Lisa Hanusiak
I C F Technology, Inc
Environmental Protection
Agency - Region 9
AR 249
AR 250
AR 2S1
92/01/15 Stephen Lyon
Conklin Bros - Contract
Div
92/01/29 Dave McCain
McCain Environmental
Services
92/02/25 Dave McCain
McCain Environmental
Services
Robert Bernstein
Environmental Protection
Agency - Region 9
Robert Bornstein
Environmental Protection
Agency - Region 9
Robert Bornstein
Environmental Protection
Agency - Region 9
•XV1S59, new *03. 3 soil
saaples for RAS
volatiles, collected
9/18/91 i 9/23/91, u/TL
to J Lucey fr V Taylor
Data validation rpt: Case
M.V1S59. nemo #4. 20 soiI
samples for RAS t SAS
volatile*, collected
9/18/91-9/25/91, u/TL to
J Lucey fr V Taylor
Data validation rpt: Case
«LV1S59, nemo 001, 6 soil
samples for RAS ft SAS
volatiles. collected
8/29/91-9/6/91, u/TL to J
Lucey fr V Taylor
Data validation rpt: Case
*LV1S59, memo #02, 21
soil saaples for RAS t
SAS volatiles, collected
9/10/91-9/20/91. u/TL to
J Lucey fr V Taylor
Ltr: Notification that
all remaining drill
cutting dniBs at Hal ford
Cleaners belong to
Ecology A Environment,
Inc
Ltrt Transmits results of
1/24/92 air sampling
taken fr vapor extraction
system at HaIford
Cleaners, u/marginalia &
attchs
Ltr: Transmits results of
2/23/92 air sampling
taken fr vapor extraction
system at HaI ford
Cleaners, w/attchs
-------
Page 27
07/10/97
Hodesto Grounduater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR 0
ROLL 0 FRAME 0
DATE
yy/m/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 252
AR 253
AR 254
92/03/03 Robert Bernstein Steve Lyons
Environmental Protection Conklin Bros
Agency - Region 9
92/03/23 US Dept of Health & Hunan
Services
92/04/15 Jack Sheets
I C F Technology, Inc
Environmental Protection
Agency - Region 9
AR 255
92/04/23
Raneen Moezzi
I C F Technology, Inc
Environmental Protection
Agency - Region 9
AR 256
92/04/24
Dave McCain ,
McCain Environmental
Services
AR 257
92/04/29 Ian Jensen
I C F Technology.
Inc
Robert Bernstein
Environmental Protection
Agency - Region 9
Environmental Protection
Agency • Region 9
AR 258
92/05/01 Barbara Gordon
I C F Technology, Inc
Environmental Protection
Agency - Region 9
AR 259
92/05/05 Barbara Cordon
I C F Technology,
Inc
Environmental Protection
Agency - Region 9
Ltr: Requests that PID
readings continue to be
taken weekly to ensure
carbon canisters are
functioning properly
Interim preliminary
health assessment, w/TLs
Data validation rpt: SAS
07047Y, memo 002, 9 gu
samples for SAS metals &
molybdenum, collected
2/24/92 ft 2/25/92, w/TL
to J Lucey fr V Taylor
Data validation rpt: Case
0LV2S32, nemo #4, 9 water
samples for RAS
pesticides/PCBs,
collected 2/24/92 C
2/25/92, w/TL to J Lucey
fr C Studeny
Ltr: Recommends
installing 3rd sampling
port at HaIford Cleaners
I taking 3rd lab sample
on 6-week basis, w/attch
Data validation rpt: Case
017812, memo 01, 18 soil
samples for RAS
volatiles, collected
2/10/92 1 2/13/92, w/TL
to J Lucey fr C Studeny
Data validation rpt: Case
0LV2S32, memo Ml, 9
water samples for RAS ft
SAS volatiles, collected
2/24/92 4.2/25/92, w/TL
to J Lucey fr C Studeny
Data validation rpt: Case
017718, memo 001, 14 soil
samples for RAS
volatiles, collected
2/3/921-2/5/92, w/TL to J
Lucey fr C Studeny
-------
Page 28
07/10/97
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR *
ROLL * FRAME *
DATE
yy/im/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 260
92/05/13 Ian Jensen
I C f Technology, Inc
Environmental Protection
Agency - Region 9
AR 261
92/05/13 Ian Jensen
I C F Technology, Inc
Environmental Protection
Agency - Region 9
AR 262
92/06/11 Lisa Hanusiak
I C F Technology, Inc
Environmental Protection
Agency - Region 9
AR 263
92/06/18 Lisa Hanusiak
I C F Technology, Inc
Environmental Protection
Agency - Region 9
AR 264
92/07/14 Frances McChesney
CA Regional Water Quality
Control Board - Central
Valley Region
AR 265
92/07/16 Ann Do
I C F Technology, Inc
Environmental Protection
Agency - Region 9
AR 266
92/07/16 Anh Do
I C F Technology, Inc
Environmental Protection
Agency • Region 9
Data validation rpt: Case
•XV2S32, memo #3, 9 water
samples for HAS
semlvolatiles, collected
2/24/92 I 2/25/92, w/TL
to J Lucey fr C Studeny
Data validation rpt: Case
(TLV2S32, memo #3. 9 water
samples for RAS
semivolatiles, collected
2/24/92 ft 2/25/92, w/TL
to J Lucey fr C Studeny,
u/attchs
Data validation rpt: SAS
•7047Y, mean MS, 9 water
samples for
radioactivity, collected
2/24/92 & 2/25/92, w/TL
to J Lucey fr C Studeny
Data validation rpt: SAS
•7047Y, memo #05. 9 water
samples for
radioactivity, collected
2/24/92 ft 2/25/92
(revised), w/TL to J
Lucey'fr C Studeny
Memo: ARARs, to-be-
considered requirements
(TBCs) & permit
requirements of CERCLA,
w/attchs 1-3
Data validation rpt: SAS
«7047Y. memo *06, 9 water
samples for SAS
herbicides, collected
2/24/92 & 2/25/92, w/TL
to J Lucey fr C Studeny,
w/attchs
Data validation rpt: SAS
I7047Y. memo *06, 9 water
samples for SAS
herbicides, collected
2/24/92 & 2/25/92, w/TL
to J Lucey fr C Studeny
-------
Page 29
07/10/97
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR tf
ROLL 0 FRAME #
DATE
yy/ran/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 267
AR 268
93/09/22 City of Modesto
93/11/15 Blake Brown
I C F Technology, Inc
Environmental Protection
Agency - Region 9
AR 269
93/12/03 Frank Arceneaux
I C F Technology, Inc
Environmental Protection
Agency - Region 9
AR 270
AR 271
93/12/03 Margie Ueiner
I C F Kaiser Engineers,
Inc
93/12/30 Fernando Contreras
I C F Technology, Inc
John Lucey
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
PCE (tetrachloroethylene)
results - historical data
well 11 (tables)
Data validation rpt: Case
#21046/79430-02, memo
#01. 6 water samples for
total suspended solids,
collected 10/18/93, w/TL
to J Lucey fr C M Weiner
Data validation rpt: Case
421046/SAS 80190-02, nemo
#02, water samples for
organ!cs, collected
10/18/93 (amended), w/TL
to J Lucey fr M Ueiner
TL: Data validation rpt.
Case 21046/80190-02, Memo
#02, 8 water samples for
SAS volatiles (11/24/93.
amended 12/3/93)
Data validation rpt: Case
#21046, memo #03, 8 water
samples for RAS total
metals, collected
10/18/93, w/TL to J Lucey
fr N Ueiner
AR 272
AR 273
AR 274
94/01/19 Fernando Contreras
I C F Kaiser Engineers,
Inc
94/01/21 An]ana Vig
I C F Kaiser Engineers,
Inc
94/02/04 City of Modesto • Public
Works C Transportation
Dept
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
Data validation rpt: Case
#21046, memo #04, 8 water
samples for RAS dissolved
metals, collected
10/18/93, w/TL to J Lucey
f r H Weiner
Data validation rpt: SAS
#8220T-01, memo #01, 14
soil gas samples for SAS
votatflea, collected
11/21/93-11/23/93, w/TL
to J Lucey fr M Ueiner
Water quality data for
PCE & TCE, w/TL fr M
Gil ton to J Lucey 2/10/94
AR 275
94/07/15 Yugal Luthra
Enmanuel Mensah
Memo: Review of baseline
-------
Page 30
07/10/97
Modesto Grwndwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR *
ROLL * FRAME 0
DATE
yy/nn/dd
AUTHOR
ADDRESSEE
SUBJECT
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
risk assessment
AR 276
94/07/27 David Parson
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
Eonanuet Nensah
CA Environmental
Protection Agency • Dept
of Toxic Substances
Control
Memo: Review of FS
(feasibility study)
AR 277
94/07/27 Erananuel Hensah
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
John Lucey
Environmental Protection
Agency - Region 9
TL: Transmits comments on
FS (feasibility study) &
rick assessment
AR 278
AR 279
AR 280
AR 281
AR 282
AR 283
94/08/29 Emmanuel Mensah
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
95/03/00 Lockheed Idaho
Technologies Co
95/03/15 Ecology A Environment,
Inc
95/05/15 Ecology A Environment,
Inc
John Lucey
Envi ronmentaI Protect < on
Agency • Region 9
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
Ltr: Transmits comments
on FS (feasibility study)
A risk assessment, w/o
attch
Draft treatment
alternatives rpt, w/TL fr
C Hulet to 1C Brown
3/14/95
Phase 3 RI (remedial
Investigation) workplen
(Privileged, FOIA exs 4 A
5)
Phase 3 RI (remedial
investigation) workplan
(Redacted, FOIA exs 4 A .
5)
95/05/24 Bruce Diamond Environmental Protection Nemo: Final policy toward
Environmental Protection Agency owners of property
Agency - Region 9 containing contaminated
aquifers .
95/07/21 David Parson
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
Ennanuel Hensah
CA Environmental
Protection Agency - Dept
'of Toxic Substances
Control
Mono: Review of Phase 3
RI (remedial
investigation) field
sampling QAPP, w/attch A
AR 284
95/08/00 Ecology & Environment, Environmental Protection Phase 3 field sampling
-------
Page 31
07/10/97
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR *
ROLL * FRAME *
DATE
yy/mm/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 285
AR 286
AR 287
AR 288
AR 289
AR 290
AR 291
AR 292
Inc
95/08/11 Mark Petersen
Environmental Protection
Agency - Quality
Assurance Management
Section
95/09/00 Patricia Mack
Environmental Protection
Agency - Region 9
95/10/23 Karen Pettit
I C f Kaiser Engineers,
Inc
95/10/23 Karen Pettit
I C F Kaiser Engineers,
Inc
95/11/17 Mi til Dooley
1 C F Kaiser Engineers,
Inc
95/11/21 Mitzi Dooley
I C F Kaiser Engineers,
Inc
95/11/21 Mitzi Dooley
I C F Kaiser Engineers,
Inc
95/11/22 Caron Sontag
I C F Kaiser Engineers,
Agency - Region 9
John Lucey
Environmental Protection
Agency - Region 9
John Lucey
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
Environmental Protection
Agency • Region 9
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
QAPP
Memo: Approves final
field sampling quality
assurance project plan
, phase 3 remedial
investigation
Memo: Transmits soil &
groundwater data for
samples collected 8/21 -
9/22/95, w/attch
Data validation rpt: Case
423953, memo #01, ° water
samples for total metals,
collected 8/29/95-
8/31/95, w/TL to J Lucey
fr M Ueiner
Data validation rpt: Case
£23953, memo 4102, 9 water
samples for dissolved
metals, collected
8/29/95-8/31/95, w/TL to
J Lucey fr M Weiner
Pata validation rpt: Case
(TCMS-95-03S, memo «01, 2
toil samples for bulk
density, collected
9/11/95, w/TL to J Lucey
fr N Weiner
Data validation rpt: Case
WMS-95-03S, memo #02. 20
soil samples for bulk
density, collected
8/21/95-8/30/95, w/TL to
J Lucey fr N Weiner
Data validation rpt: Case
#CMS-95-03S, memo #03, 17
soil samples for bulk
density, collected
8/31/95-9/7/95, w/TL to J
Lucey fr M Weiner
Data validation rpt: Case
#24035, memo #01, 8 water
-------
Page 32
07/10/97
Modesto Crounduater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR 0
ROLL 0 FRAME 0
DATE
yy/sm/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 293
95/11/22
tnc
Caron Sontag
I C F Kaiser Engineers,
Inc
Environmental Protection
Agency - Region 9
AR 294
AR 295
AR 296
AR 297
AR 298
AR 299
95/11/22 Patricia Mack
Environmental Protection
Agency • Region 9
95/11/22 Margie Ueiner
I C F Kaiser Engineers,
Inc
95/11/28 Mike Mclntosh
I C F Kaiser Engineers,
Inc
95/11/29 Mike Mclntosh
I C F Kaiser Engineers,
Inc
95/11/29 Mike Mclntosh
I C F Kaiser Engineers,
Inc
95/11/29 Margie Weiner
I C F Kaiser Engineers,
Inc
John Lucey
Environmental Protection
Agency - Region 9
John Lucey .
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
John Lucey
Environmental Protection
Agency • Region 9
samples for total ft
dissolved netals,
collected 9/19/95, w/TL
to J Lucey fr M Ueiner
Data validation rpt: Case
0R95S78, memo «01. 9
water samples for
dissolved ft suspended
solids, collected
8/29/95-8/31/95, w/TL to
J Lucey fr M Ueiner
Hew: Transmits
groundwater data for
samples collected 8/21 &
8/23/95, w/attch
Mean: Notification of
transarittal of
unvalidated data ft data
reporting qualifiers to .
Chris Lichens of Ecology
ft Environment, Inc
Data validation rpt: Case
0CMS-95-04S, memo 001, 20
soil samples for total
organic carbon, collected
8/21/95-8/30/95, w/TL to
J Lucey fr H Ueiner
Data validation rpt: Case
«CMS-95-04S, memo 002, 17
soil samples for total
organic carbon, collected
8/31/95-9/7/95, w/TL to J
Lucey fr N Ueiner
Data validation rpt: Case
fCHS-95-04S, mem 003, 2
soil samples for total
organic carbon, collected
9/11/95, w/TL to J Lucey
fr M Ueiner
Mean: Notification that
unvalidated data ft data
reporting qualifiers have
been forwarded to Chris
-------
Page 33
07/10/97
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER.ORDER
AR *
ROLL * FRAME
DATE
yy/mn/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 300
AR 301
AR 302
95/12/04 Joe Eidelberg
Environmental Protection
Agency - Region 9
9S/12/06 Mitzi Dooley
I C F Kaiser Engineers,
. Inc
95/12/12 Mitzi Dooley
1 C F Kaiser Engineers,
Inc
Environmental Protection
Agency • Region 9
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
AR 303
AR 304
AR 305
AR 306
95/12/21 Mike Mclntosh
I C f Kaiser Engineers,
Inc
95/12/22 Mike Mclntosh
I C F Kaiser Engineers,
Inc
95/12/27 Mike Mclntosh
I C F Kaiser Engineers,
Inc
95/12/27 Karen Pettit
I C F Kaiser Engineers,
Inc
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
Lichens of Ecology I
Environment, Inc
Data validation rpt: Case
0R95S78, 5 groundwater
samples for various
factors, collected
9/19/95 A 10/11/95. w/TL
to J Lucey fr J Eidelberg
Data validation rpt: Case
#24067, meno «01, 2 water
samples for total I
dissolved metals,
collected 10/11/95, w/TL
to J Lucey fr H Ueiner
Data validation rpt: Case
*R9SS78, meno *02, 5
Mater samples for total &
dissolved solids,
collected 9/19/95 &
10/11/95, u/TL to J Lucey
fr H Ueiner
Dats validation rpt: Case
*CMS-95-13D. memo «01, 14
water samples for radon-
222, collected 8/29/95-
10/11/95, w/TL to J Lucey
fr M Ueiner
Data validation rpt: Case
*CMS-95-12D, memo 001, 14
water samples for
radioactivity, collected
8/29/95-10/11/95, w/TL to
J Lucey fr M Ueiner
Data validation rpt: Case
*CMS-95-05S, memo Ml, 20
soil samples for particle
size, collected 8/21/95-
8/30/95, w/TL to J Lucey
fr M Ueiner
Data validation rpt: Case
0CMS-95-05S, memo #02, 17
soil samples for particle
size, collected 8/31/95-
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Page 34
07/10/97
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
Aft * ROLL * FRAME
DATE
yy/nn/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 307
AR 308
95/12/27 Karen Pettit
I C F Kaiser Engineers,
Inc
96/02/08 Mitzi Dooley
I C F Kaiser Engineers,
Inc
Environmental Protection
Agency - Region 9
Environmental Protection
Agency - Region 9
AR 309
96/02/15 Caron Sontag
t C F Kaiser Engineers,
Inc
Environmental Protection
Agency - Region 9
AR 310
AR 311
AR 312
AR 313
96/03/08 Joe Eidelberg
Environmental Protection
Agency - Region 9
96/03/11 Patricia Mack
Environmental Protection
Agency - Region 9
John Lucey
Environmental Protection
Agency - Region 9
AR 3H
96/05/02 CA Regional Water Quality
Control Board - Central
Valley Region
96/05/02 CA Regional Water Quality
Control Board - Central
Valley Region
96/05/06
9/7/95, w/TL to J Lucey
fr H Weiner
Data validation rpt: Case
*MS-95-05S. memo «03, 2
soil samples for particle
size, collected 9/11/95,
w/TL to J Lucey fr N
Weiner
Data validation rpt: Case
fOS-95-060 t CMS-95-070,
memo #01, 14 water
samples for uranium I
radium, collected 8/95-
10/95, w/TL to J Lucey fr
M Weiner
Data validation rpt: Case
M95S78. nemo *03, 14
water samples for
biochemical oxygen
demand, collected
8/29/95-10/11/95, w/TL to
J Lucey fr M Weiner
Data validation rpt: Case
fR95S78, 9 groundwater
samples for various
factors, collected
8/29/95-8/31/95, w/TL to
J Lucey fr J Eldelberg
Memo: Transmits soil data
for samples collected
8/21 I 9/13/95, w/attch
Regional Board ARARs for
groundwater remediation,
w/marginalia
Regional Board ARARs for
groundwater remediation
(addendum to 4/25/94
subaittal) w/TL to M
Shut! fr E Nensah
Sign-in sheet for 5/6/96
Modesto water quality mtg
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Page 35
07/10/97
Modesto Groundwater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AR
ROLL « FRAME tf
DATE
yy/nn/dd
AUTHOR
ADDRESSEE
SUBJECT
AR 315
AR 316
96/07/00 Environmental Protection
Agency - Office of
Emergency & Remedial
Response
96/07/29 Chris Lichens
Ecology ft Environment,
Inc
Alice Tulloch
City of Modesto • Public
Works & Transportation
Dept
AR 317
AR 318
AR 319
AR 320
AR 321
96/08/20 Antonio Tovar Chris Lichens
City of Modesto - Public Ecology ft Environment,
Works & Transportation Inc
Dept
96/09/00 Environmental Protection
Agency - Region 9
96/10/02 CA Regional Water Quality
Control Board
96/12/20 Ecology A Environment,
Inc
User guide to VOCs in
soils presumptive remedy
Ltr: Requests input on
acceptable levels of
tetrachl'oroethylene (PCE)
& naturally occuring
uranium discharged to
sewer or drinking water
system
Ltr: Provides acceptable
levels of
tetrachloroethylene (PCE)
I naturally occuring
uranium discharged to
sewer or drinking water
system, w/o encl
Article: Use of natural
processes in CERCLA
groundwater remedies
(final draft)
Amended resolution #92-
49, H/TLs
Environmental Protection Phase 3 Rt (remedial
Agency - Region 9 investigation) rpt
97/02/07 Michelle Schutz
Environmental Protection
Agency - Region 9
Eananuel Mensah
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
Ltr: Request for CA state
applicable or relevant t
appropriate requirements
(ARARs) analysis for site
AR 322
AR 323
AR 324
97/03/00 Ecology ft Environment,
Inc
97/03/26 Michelle Schutz
Environmental Protection
Agency - Region 9
97/04/24 Environmental Protection
Agency - Region 9
Environmental Protection Draft FS (feasibility
Agency - Region 9 study)
Wendy Cohen Ltr: Requests comments on
CA Regional Water Quality transmitted Draft FS
Control Board - Central (feasibility study) w/o
Valley Region encl
Mtg agenda: EPA/State of
CA meeting re feasibility
study for site
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Page 36
07/10/97
AX ff
ROLL 0 FRAME «
DATE
yy/m/dd
Modesto Grounduater Contamination
Modesto, California
ADMINISTRATIVE RECORD CUMULATIVE INDEX
AR NUMBER ORDER
AUTHOR
ADDRESSEE
SUBJECT
AR 325
AR 326
AR 327
AR 328
AR 329
AR 330
AR 331
AR 332
97/04/25 Phillip Toralin
City of Modesto - Public
Works I Transportation
Oept
97/05/06 Environmental Protection
Agency - Region 9
97/05/08 Emnnuel Mensah
CA Environmental
Protection Agency - Dept
of Toxic Substances
Control
97/06/00 Ecology & Environment,
Inc
97/06/30 Richard Hume
CA. Environmental
Protection Agency - Dept
of Toxic Substances
Control
97/07/00 Environmental Protection
Agency - Region 9
97/07/00 Ecology I Environment,
Inc
97/07/09 Environmental Protection
Agency
Michelle Schutz
Environmental Protection
Agency - Region 9
Michelle Schutz
Environmental Protection
Agency • Region 9
Environmental Protection
Agency - Region 9
Michelle Shutz
Environmental Protection
Agency - Region 9
Memo: Transmits pages
froB Modesto Municipal
Code regarding local
industrial limit, w/attch
Agenda A handouts
5/6/97 remedial
alternatives mtg
for
Ltr: Comments on Draft FS
(feasibility study)
FS (feasibility study)
Ltr: Comments on FS
(feasibility study)
Fact sheet: Proposed plan
for gu cleanup project
Environmental Protection Baseline hman health
Agency • Region .9 risk assessment
List of EPA guidance
docunents consulted
during selection of
clean-up action
No. of Records:332
\araricro3.rpt
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APPENDIX B
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS (ARARS)
-------
TaReB-1
Federal and State
Applicable or Relevant and Appropriate Requirements (ARARs)
Porter-Cologne
Water Quality
Control Act, Cal.
Water Code §
13000,13140,
13240
State Water Resources
Control Board Resolution
No. 88-63, -Sources of
Drinking Water Policy"
Applicable
Specifies that, with some exceptions, all ground-
and surface waters are considered suitable, or
potentially suitable, for municipal or domestic
water supply.
Action-specific ARAR that applies in
determining beneficial uses for waters affected
by waste discharges. Under this Resolution,
groundwater at the Site is a potential source of
drinking water.
Safe Drinking
Water Act, 40
U.S.C. § 300f, et
seq.; Cal. Safe
Drinking Water
Act, Cal Health &
Safety Code §
4010
National Primary Drinking
Water Regulations, 40 CFR
part 141, § 141.61 (PCE
MCL); Title 22 CCR.S
64444, Table 64444-A
(toluene MCL)
Potentially
Applicable
Requirements applicable to public water systems.
Establish "maximum contaminant levels" (MCLs),
the maximum permissible level of a contaminant in
water which is delivered to any user of a public
water system. MCLs are health-based standards.
Establish "maximum contaminant level goals"
(MCLGs), heath goals at which no known health
effects would occur.
Federal and state MCLs are not ARARs for
groundwater cleanup for this interim action
because such a determination is outside the scope
of this interim/source remedy. Groundwater
cleanup standards will be determined in the final
remedial action for the Site. Federal and state
MCLs apply to treated water that is served to
users of a public water system and would apply
to any water supplied to the Modesto water
system under this interim action.
Federal Clean
Water Act, §1251,
et seq., and 40
CFRpt. 122
National Pollution
Discharge Elimination
System, implemented by
State Water Resources
Control Board Orders 92-
08 and 92-13
Applicable
Requirements for certain industrial and
construction activities to ensure storm water
discharges do not contribute to a violation of
surface water quality standards. Includes measures
to minimize or eliminate pollutants in storm water
discharges and monitoring to show compliance.
Potentially applicable to construction of
treatment units, as determined during the
remedial design phase.
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Table B-l
Federal and State
Applicable or Relevant and Appropriate Requirements (ARARs)
Porter-Cologne
Water Quality
Control Act, Cal.
Water code §§
13140-47,13172,
13260,13263,
13267,13304
Title 23 California Code of
Regulations, Division 3,
Chapter 1S,§ 25 ll(d)
Relevant and
Appropriate
Exempts public agency cleanups from Chapter 15
regulations if waste is discharged according to Art
2 of Chapter 15 for waste disposed to land.
Requires compliance with Chapter 15 requirements
"to the extent feasible" if the remedial action will
contain wastes at the Site.
Action-specific ARAR is not applicable, but
relevant and appropriate, because Chapter 15
applies to only specifically enumerated waste
management units, which do not include this
Site. Exempts public agency remediations from
most requirements of Chapter 15. Requirement to
comply with Article 2 is potentially relevant and
appropriate to disposal of any wastes to land.
Art 2 does not apply to wastes that may be
discharged directly or indirectly to waters of the
State of California.
Clean Air Act, 42
U.S.C..§7401,et
seq.
California State
Implementation Plan (SIP).
Relevant and
Appropriate
The SIP describes how the air quality programs of
the State will be implemented to meet compliance
with the Clean Air Act standards, including
ambient air standards.
Remedial actions should comply with relevant
substantive requirements of the SIP.
Clean Air Act, 42
U.S.C.§7401,et
seq.
San Joaquin Valley Unified
Air Pollution Control
District, Rule 2201
Applicable
New and modified stationary sources rule requires
application of best available control technology to
new or modified emissions unit if unit would
increase emissions more than 2 pounds per day.
Action-specific ARAR for controlling air
emissions from soil vapor and groundwater
treatment units, applicable depending on quantity
and types of air emissions.
Clean Air Act, 42
U.S.C. § 7401, et
seq.
San Joaquin Valley Unified
Air Pollution Control
District, Rule 4101
Applicable
Visible emission limits prohibit emission of more
than 3 minutes/hour of certain types of visible
emissions.
Action-specific ARAR for controlling air
emissions from soil vapor and groundwater
treatment units
Clean Air Act, 42
U.S.C. §7401, et
seq.
San Joaquin Valley Unified
Air Pollution Control
District, Rule 4102
Applicable
Prohibits discharge of air contaminants that will be
a nuisance or will endanger the public.
Action-specific ARAR for controlling air
emissions from soil vapor and groundwater
treatment units.
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TlBle B-l
Federal and State
Applicable or Relevant and Appropriate Requirements (ARARs)
Clean Air Act, 42
U.S.C. § 7401, et
seq.
San Joaquin Valley Unified
Air Pollution Control
District, Rule 4201
Applicable
Paniculate matter emission standard prohibits
emission of dust, fumes or total suspended
paniculate matter of greater than 0.1 grain per
cubic foot of gas at dry standard conditions.
Prescribes certain EPA analytical methods.
Action specific ARAR for controlling air
emissions from soil vapor and groundwater
treatment units.
Resource
Conservation and
Recovery Act, 42
U.S.C. § 6901, et
seq.
Air Emission Standards for
Process Vents, 40 CFR
Part 264, SubpartAA
Applicable
Air emission standards for process vents associated
with air stripping operations managing hazardous
wastes with organic concentrations of at least 10
ppmw.
Action-specific ARAR potentially applicable to
air strippers used in groundwater remediation,
depending on concentrations of extracted
groundwater.
EPA Guidance
OSWER Directive No.
9355.0-28
Applicable
Guidance on the control of air emissions from air
strippers for groundwater treatment at Superfund
sites, limiting emissions to 15 pounds per day.
Action-specific ARAR for the air stripper to be
used in the groundwater treatment remedy.
22 CCR§ 66261.24(8)
Applicable
Establishes methods for determining hazardous
waste classifications and sets characteristic of
toxicity level for PCE.
Chemical-specific ARAR for determining waste
classifications.
22 CCR § 64445.2
Relevant and
appropriate
Establishes sampling requirements for treated water
and source water for certain public water supplier.
Action-specific requirements for certain public
water suppliers are not applicable because the
Site is not a water supplier. Relevant and
appropriate ARAR for monitoring of treatment
of groundwater if treated groundwater is
delivered to the public drinking water supply
system.
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Table B-l
Federal and State
Applicable or Relevant and Appropriate Requirements (ARARs)
Resource
Conservation and
Recovery Act,
Subtitle C, 42
U.S.C. §6921, et
seq.; Hazardous
Waste Control Act,
Cal. Health &
Safety Code §
25100, et seq.
Cal. Code of Regulations,
Title 22, Division 4.5,
Chapter 18, § 66268.7(a).
Applicable
Requires generators to determine whether waste is
subject to land disposal restrictions.
Requirement to determine whether carbon
filtration units from treatment of vapors are
subject to land disposal restrictions is applicable.
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