United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R09-87/016
June 1987
3 EPA Superfund
Record of Decision:
Stringfellow Acid Pits, CA
-------
TECHNICAL REPORT DATA
'rleau rtaii tnttnictiont on tit rtvtnt to fort i
1. MtPORT NO.
EPA/ROD/R09-87/016
3.
3 »€Ci"6Nr 3 ACCESS.CN NO
I. TlTLi ANOSU«TITH
SUPERFUND RECORD OF'DECISION
Stringfellow Acid Pits, CA
Second Remedial Action
June 25, 1987
6. M«*OKMING ORGANIZATION COOi
7. AUl
«f I»OHT SO
IO Oi
10. 'MOGMAM
NO
12. SPONSORING AGgNCV NAMi ANO AOOftfSS
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. TYM Of MPORT ANO *€«ioo cove«eo
Final ROD Report
14. SPONSORING AQINCV COOS
800/00
It. SU?»klMINTAAY NOTIS
The Stringfellow site is located in Riverside County, California, approximately 1
mile north of the community of Glen Avon. Between August 1956 and November 1972, the
Stringfellow Quarry Company operated a hazardous waste disposal facility at the site.
Approximately 34,000,000 gallons of industrial waste, primarily from metal finishing,
electroplating, and DDT production were deposited in onsite evaporation ponds. Spray
evaporation procedures were used to accelerate the reduction of pond content volume. In
1972, the site was voluntarily closed. In 1969 and 1978, excessive rainfall caused the
disposal ponds to overflow into Glen Avon. In 1980 and 1981, the Santa Ana Regional
Water Quality Control Board (RWQCB) implemented an Interim Abatement Program at the
site, as the first phase of site closure. The program included removal of all surface
liquids; partial neutralization and capping of wastes; installation of a gravel drain
and an onsite downgradient well network; surface water diversion channels; and
construction of a downgradient clay core barrier dam and leachate collection system. A
July 1984 ROD approved of the installation of an onsite ground water facility using lime
precipitation for heavy metals followed by granular activated carbon treatment for the
removal of organics, with initial discharge to POTW and final discharge to the ocean.
The primary contaminants of concern affecting onsite and downgradient ground water
include: VOCs including TCE, organics, inorganics, and metals.
(See Attached Sheet)
17.
KIY WOMO* AMD OOCUMINT
oiscmrroM*
b.lOIMTI'IINS/OMN INOtO T|*M*
c. COSAti
Record of Decision-
Stringfellow Acid Pits, CA
Second Remedial Action
Contaminated Media: gw, sw
Key contaminants: organics, TCE, heavy meta
sulfates, nitrates, flouride
DISTRIBUTION STATIMINT
it. stcuiiTY C
None
39
29. StCuAiTv ClAU i Hit* p
-------
EPA/ROD/R09-87/016
Stringfellow Acid Pits, CA
Second Remedial Action
16. ABSTRACT (continued)
The selected remedial action for this site includes: installation of a ground water
barrier system in the lower canyon area and treatment of extracted ground water, if
necessary, followed by discharge to a POTW; installation of a peripheral channel around
the north end of the original site to direct upgradient surface water runoff; and
extension of the existing gunite channels southward to discharge surface water to Pyrite
Creek. The estimated capital cost for the selected remedy is J51,047,000-£l,136,000 with
annual O&M of $1,243,000-$!,408,000.
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Record of Decision
Early Implementation Action
Remedial Alternative Selection
Site: Stringfellow Acid Pits/ Glen Avon, California
DOCUMENTS REVIEWED
My decision is based in part on review of the following
documents describing the analysis of cost-effectiveness of remedial
alternatives for the Stringfellow site:
- Summary of Remedial Alternative Selection
(attached)
- Responsiveness Summary (attached)
- "Assessment of an Extraction Well Barrier in the Lower
Canyon/ a Proposed Early Implementation Action at the
Stringfellow Hazardous Waste Site/" Draft Report, SAIC,
December 16, 1986.
- "An Assessment of Drainage Improvements at the North
End of the Canyon, a Proposed Early Implementation Action
at the Stringfellow Hazardous Waste Site," Draft Report,
SAIC, February 3, 1987.
- July 18, 1984 Record of Decision for the Stringfellow Acid
Pits Site.
- Summary of Remedial Alternative Selection for the July 18,
1984 Record of Decision for the Stringfellow Acid Pits
Site.
- Responsiveness summary addressing the comments made by
governmental agencies and the public concerning the Fast
Track Remedial Investigation/Feasibility Study (Fast Track)
report for the Stringfellow site, Riverside, California,
issued May 18, 1984.
DESCRIPTION OF SELECTED REMEDY
- Installation of a groundwater barrier system in the lower
canyon area and treatment of extracted groundwater, if
necessary, followed by discharge to a POTW.
- Installation of a peripheral channel around the north end
of the original site to direct upgradient surface water
runoff.
-------
-2-
- Based on the July 18, 1984 Record of Decision, the existing
gunite channels will be extended southward to discharge
surface water to Pyrite creek. The length of extension of
the gunite channels will depend on an evaluation presently
being conducted by the State of California Department of
Health Services.
DECLARATION
Consistent with the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA)/ as amended by
the Superfund Amendments and Reauthorization Act of 1986 (SARA
or 1986 Act), and the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP), 40 C.F.R. Part 30C, 1 have
determined that at the Stringfellow site, the selected remedial
alternative is a cost-effective measure and provides adequate
protection of public health and welfare and the environment.
The State of California has been consulted and concurs with the
approved remedy. In addition, the action will require operation
activities to ensure the continued effectiveness of the remedy.
These activities will be considered part of the approved action
and eligible for Trust Fund monies until implementation of the
remedial action for final closure.
I have also determined that the action being taken is consistent
with Section 121 of SARA and is appropriate when balanced against
the availability of Trust Fund monies for use at other sites.
The State of California is currently conducting a full-scale
Remedial Investigation/Feasibility Study to identify and evaluate
methods to prevent or manage upstream groundwater and surface
water entering the site, to prevent migration of hazardous
substances off-site, and to define aquifer characteristics, the
extent of the contaminant plume, and methods of controlling
migration. A cost-effective remedial action for final site
closure will be developed. If additional remedial actions are
determined to be necessary, a Record of Decision will be prepared
for approval of future remedial actions.
B7
Date W John Wise
Deputy Regional Administrator
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SUMMARY OF REMEDIAL ALTERNATIVE SELECTION
(EARLY IMPLEMENTATION ACTIONS)
STRINGFELLOW ACID PITS
Glen Avon, California
SITE LOCATION AND DESCRIPTION
The Stringfellow site is located in Riverside County, ap-
proximately 5 miles northwest of the City of Riverside and
one mile north of the community of Glen Avon. The site is
located at the head of Pyrite Canyon which lies in the south-
ern portion of the Jurapa Mountains, approximately 4,500 feet
north of the intersection of U.S. Highway 60 and Pyrite
Street (see Figure 1). Stringfellow site investigation areas
referred to in this document are defined in Figure 2.
The watershed area tributary to the disposal site is approx-
imately 270 acres. Groundwater beneath the site moves in an
aquifer bounded by canyon walls t'o the north, east and west.
Water flows toward the south, exiting the canyon just north
of Highway 60 and entering the regional groundwater system
under the Glen Avon community, and then travels toward the
southwest. The groundwater supply is also used for indus-
trial and agricultural purposes. Surface runoff from the
canyon moves southwesterly from the site and collects in a
culvert drop box just north of Highway 60. Surface runoff
then flows under the highway through Glen Avon in lined and
unlined channels, and eventually to the Santa Ana River, a
total distance of approximately 7 miles.
The site is surrounded by undeveloped land which is primarily
used as rangeland. An operating quarry is located about a
quarter of a mile downgradient of the site on the western
side of the canyon.
SITE HISTORY
The site was operated by the Stringfellow Quarry Company
from August 21, 1956 to November 19, 1972 as a hazardous
waste disposal facility. Approximately 34 million gallons
of industrial wastes, primarily from metal finishing, elec-
troplating and DDT production, were deposited in evaporation
ponds on the site. Site operations also included spray ev-
aporation of pond contents to accelerate volume reduction.
The total disposal area was approximately 17 acres. The
site was voluntarily closed in 1972. In 1969 and 1978, ex-
cessive rainfall caused the disposal ponds to overflow. The
overflows extended south of Highway 60 into Glen Avon. In
1980 and 1981, the Santa Ana Regional Water Quality Control
Board (RWQCB) implemented an Interim Abatement Program at
the disposal site as the first phase of site closure. The
- 1 -
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SAN BERNARDINO COUNT*
RIVERSIDE COUNTY __'
*.--"
STRINGFELLOW
SITE
JURUPA MOUNTAINS
MISSION BLVO
GLEN AVON
ELEMENTARY
SCHOOL
GALENA ST
fEOLEY HILLS
FIGURE 1 Location of
WMM Dttpoul
-------
/
/UPGRADIENT
UPGRADIENT
\
\
•00
500
•CALi IN FEf T
1000
FIGURE 2 Stringfellow Site Jnvwtioation Area*
-------
program included removal of all surface liquids, partial
neutralization and capping of the wastes, installation of a
gravel drain and a network of extraction, interceptor and
monitoring wells onsite and downgradient of the site, diver-
sion of surface water around the site via concrete channels,
and construction of a clay core barrier dam and leachate
collection system downgradient of the disposal ponds to stop
migration of subsurface leachate.
An EPA-lead Past Track Remedial Investigation/Feasibility
Study (RI/FS) was conducted by EPA's contractor CH2M HILL
from September 1983 to May 1984' to identify and evaluate
alternatives to onsite groundwater extraction and offsite
disposal operations in practice at that time. The selected
alternative, or interim measure, would be implemented during
the 3 to 5 year period prior to completion of the full-scale
RI/FS and implementation of the final remedy.
Response actions including state-lead and EPA-lead
activities through July 1984 are described in the July 18,
1984 Record of Decision (ROD) for this site. Since July
1984, three main activities continue, as described below:
PRETREATMENT PLANT
Based on the results of the Fast Track RI/FS, the July 1984
ROD documented the selection of the interim measure to in-
stall a treatment facility onsite to treat contaminated
groundwater from the onsite and downgradient areas. It also
approved the installation of additional interceptor and mon-
itoring wells to assure effective interception of contam-
inated groundwater. The pretreatment system consists of
lime precipitation for heavy metals removal followed by
granular activated carbon treatment for organics removal.
Treated effluent is trucked to a local sewer line drop point
for disposal. Effluent receives additional treatment at the
publicly-owned treatment works (POTW) and then is discharged
to the ocean. Sludge from the pretreatment process is taken
to a RCRA approved land disposal facility.
The design of the pretreatment plant was completed and went
out to bid in October 1984. Construction of the plant began
near the site in the mid-Canyon area in January 1985 and was
completed in November 1985. Design and construction of the
pretreatment facility was performed through contractors of
the California Department of Health Services (DBS). EPA's
REM II contractor, Camp Dresser and McKee (CDM) began opera-
ting the plant in December 1985. Startup operations at the
plant began in December 1985 and were completed in February
1986. During this period, responsibility for the pretreat-
ment plant was transferred to the U.S. Army Corps of Engi-
neers under an inter-agency agreement (IAG) with the EPA. A
- 4 -
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request for proposals (RFP) for operations was issued in
February 1986, and this process culminated in the selection
of CDM for long-term operations in May 1986. The amount of
groundwater extracted and treated since the startup of the
pretreatment plant is approximately 150,000 gallons per week.
The treated effluent is being trucked to a local POTW system
drop point (Santa Ana Watershed Project Authority SARI sewer
line), so that it receives additional treatment at the County
Sanitation Districts of Orange County (CSDOC) POTW. The
sludge from the pretreatment plant is disposed of at a RCRA
approved facility.
FULL SCALE RI/FS
A full scale comprehensive RI/FS is being conducted by DHS
contractor SAIC to characterize the site and to identify and
evaluate alternatives for final site cleanup. Field inves-
tigations have been completed and the draft RI report is
expected to be released for public comment during spring of
1987. An assessment of 86 potentially applicable tech-*
nologies has been conducted, and reported in July 1985.
Applicable technologies were combined into remedial action
alternatives. Initial screening of the remedial action
alternatives was performed and a draft report issued in May
1986.** Detailed evaluation of the remaining alternatives
is being performed at this time. Also/ several treatability
studies are being completed. The FS report is expected to
be completed by early 1988.
ALTERNATIVE WATER
During analysis of water samples from onsite, mid-canyon/
and community wells, radiation was detected. In response/
DHS conducted a sampling of private drinking water supply
wells in the area. At the end of the summer of 1984, DHS
initiated an interim program to provide bottled water to
nearly 400 Glen Avon residences to eliminate any dependence
11 Stringfellow Facility Remedial Investigation/Feasibility
Study Draft Interim Report on Development and Screening of
Remedial Technologies And Alternatives" by Science
Applications International Corporation, Riverside,
California, July 31, 1985.
**
"Stringfellow Facility Remedial Investigation/Feasibility
Study Combined Tasks XI and XII Development And Initial
Screening of Alternatives" by Science Applications
International Corporation, La Jolla, California, May 30,
1986.
- 5 -
-------
on groundwater near the influence of contamination from the
Stringfellow site, and to give anyone in identified areas of
elevated groundwater radioactivity, regardless of the source,
an alternative supply of domestic water. In October 1985,
Senate Bill 1063 provided state funds to hook up residences
receiving state supplied bottled water to the Jurupa Commu-
nity Services District water supply. The first connections
occurred in June 1986. Approximately 75 percent (350 resi-
dences) of the hookups have been completed, and the remaining
hookups are expected to be completed by the end of 1987.
SITE STATUS
NATURE AND EXTENT OF CONTAMINATION
This section presents information based on the July 1984 ROD
and subsequent published information. The draft RI report
expected to be released during Spring 1987 will fully present
the most recent data that are not presented here.
In general, groundwater is heavily contaminated in the onsite
area and contaminant levels decrease in the downgradient
direction. The contaminants include metals, sulfates, ni-
trates, fluoride, chloride, and a variety of organics, in-
cluding TCE, chlorobenzene, chloroform, dichlorobenzene, and
phenol. These contaminants are consistent with the types of
wastes disposed at Stringfellow. An organic material (not a
"priority pollutant"), para-chlorobenzenesulfonic acid, is a
dominant component of the onsite wastes, comprising as much
as 50 percent of the total organic matter. Although ele-
vated radiation levels are found in onsite groundwater/
leachate, radiochemical speciation analyses have not indi-
cated any relationship between Stringfellow wastes and
detections of gross alpha radioactivity at just above drink-
ing water standards in some private community wells.
Contaminated groundwater seems to be following a relatively
narrow zone (300 to 400 feet wide) in the lower canyon area.
More recent ongoing RI activities indicate a wider zone of
contaminated groundwater (approximately 900 feet wide) in
the community area. This premise is supported by soil gas
sampling and groundwater analyses from wells in these areas.
Additionally, very low concentrations of contaminants may be
found outside of this zone. Figure 3 shows the monitoring
wells near the freeway and the TCE concentrations (SAIC rou-
tine sampling data 1985) in these wells ("Assessment Of An
Extraction Well Barrier In The Lower Canyon, A Proposed Early
Implementation Action At The Stringfellow Hazardous Waste
Site" by SAIC; La Jolla, California; December 16, 1986).
The thick line on Figure 4 indicates the approximate center
of the plume. In the lower canyon area the alluvium is the
most highly contaminated unit.
- 6 -
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M«-IU 302 to 403
LC-2AI NS
LC-ZA2 24 to M
LC-UU10 to U
r
rX-lA2 2t» to 43*
»C-l*3 NO
300
W.IM NO
LC-41 MS
t
LC-UZ S3 to
•.:-i«3 2 to s
LEGEND
NO - Net OitKttd
NS - Net SMelcd
TW1e«l
NH.17B »S te 361
Well *"
TCE wo* In yfl/1
Airing 1985 from SA1C routine
ling.
FIGURE 3
CONTAMINATION IN HWY. 60 WELLS USING
TCE AS AN INDICATOR
-------
*I1
3?
400
Approx. Cehter
of Plume
I |
FIGURE 4
PLUME WIDTH APPROXIMATION USING TCE AS AN INDICATOR
-------
For a summary of the hazardous substances present and their
concentrations, refer to Table 1 and Figure 5 in this docu-
ment from the ROD signed July 18, 1984. Since that time,
new weUs have been installed in the lower canyon and commu-
nity areas (see Figure 6). Monitoring of these additional
wells has detected groundwater contamination that has
migrated downgradient from the site. Stringfellow site
related contaminants have been transported at least as far
as the area monitored by Hell FC-558A2, in the community
approximately 8,000 feet downgradient of the site (U.S. EPA
NEIC analysis results from September 1985 Stringfellow site
samples: memorandum from Dr. Joe Lowry to Thomas Dahl;
March 18, 1986) and more recent data collected as a part of
the full-scale RI/FS effort indicate that the contaminants
have migrated about 2 miles downgradient of the site. Both
chloroform and trichloroethylene were found in the sample
from this well. Sulfate, calcium, magnesium and sodium have
been transported at least as far as the area monitored by
Well FC-251A2, approximately 7,000 feet downgradient from
the site into the community. Para-chlorobenzenesulfonic
acid (p-CBSA), a byproduct of the manufacture of DDT, has
been transported at least as far as the area monitored by
Well FC-1A2 which is approximately 5,000 feet downgradient
from the site and a little south of Highway 60 (U.S. EPA
NEIC analysis results from September 1985 Stringfellow site
samples: memorandum from Dr. Joe Lowry to Thomas Dahl;
March 18, 1986). Elevated concentrations of dissolved heavy
metals and rare earths are present in onsite and downgradient
groundwaters to the vicinity of MW-8B. The concentrations
of these constituents (excluding uranium) diminish to non-
detectable levels in the mid-canyon area between MW-8B and
IW-2.
Groundwater from some of the community area monitoring wells
is contaminated with organics (TCE, chloroform, chloro-
benzene, and dichlorobenzene) at parts per billion (ug/1)
concentration levels. Organic contaminants have travelled
further from the site than metals. The concentrations of
metals tend to decrease more rapidly with distance from the
site, presumably because the metals begin precipitating as
the pH becomes more neutral away from the site and also
because of interaction with soil matter (e.g., adsorption).
In summary, a subsurface barrier wall is in place at the
south end of the site, and groundwater extraction has been
conducted since 1982 to retard the flowrate of the contam-
inated plume. Additional groundwater monitoring has detected
site-related contaminants in a plume moving downgradient of
the site into the lower canyon area and the Glen Avon commu-
nity, indicating the need for additional actions to increase
- 9 -
-------
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CONPFNTRATIOM RANGED TOR fEI mED rnM^TIT1IFflT
-------
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SOUK*: Final Put-track Remedial Iimitigition PeulbiUty Study,
May 18,1984, prepared by CH2MHILL
FIGURE 5
STRINGFELLOW SITE PLAN
(from Jury. 1984 ROD)
-------
LOWES CANYON
\
NORTHERN*
f IT AREA
SOUTHERN
f IT AREA
mtumutt
ne_, "• •— MIO CANYON-*-
•ic-i
. 102. 113. 115)
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^264. 258. 252. 251,
(FC570. 564. 558. 552)
tlClMO
EXISTING MONITORING HELLS
INTERCEPTOR WELLS
A MONITORING WELLS
MONITORING WELL CLUSTERS
A SEEPAGE ZONES
FIGURE 0
LOCATION OF REflDFNTIAI AMD MOMITOniMH WELLS MMPITO «ND
-------
the effectiveness of the current interim measures. The major
mobile priority pollutants in these areas are trichloroethy-
lene (TCE), chloroform and chlorobenzene. The TCE, chloro-
form and chlorobenzene levels listed below were found in
September 1985 at several locations as shown on Figures 5
and 6.
Concentration (ug/liter)
TCE Chloroform Chlorobenzene
Mid-Canyon (Well No. IW-2) 960 140 16
Lower Canyon (Well No. MW-17B) 540 30 . 2
Community (Well No. FC-251A2) 100 5 0.3
U.S. EPA National Enforcement Investigations Center
analysis results from September 1985 Stringfellow site
samples (memo from Dr. Joe Lowry to Thomas Dahl, March 18,
1986).
POSSIBLE ROUTES OF EXPOSURE
Soil, air, groundwater, and surface water may all be poten-
tial routes of exposure to Stringfellow contaminants. Con-
taminated soil occurs onsite, below the kiln dust layer, and
immediately downgradient of the site. However, soil is not
considered a major exposure route since the site is capped
and fenced to isolate the area from general public exposure.
Also, preliminary data from air monitoring tests conducted
by SAIC in April 1985 indicate that the capped site does not
contribute, through volatilization or suspension of wind-
carried contaminated particles, adverse levels of contami-
nants to the air. The possibility of surface water exposure
exists from surface runoff during storm events. An abnor-
mally heavy rainfall may increase the potential for this
exposure route due to the possibility of heavy erosion.
The primary concern is exposure to the groundwater since the
water supply source can be used for a variety of purposes,
including human consumption. As groundwater flows through .
the site, contaminants are transported downgradient. The
movement of this downgradient plume appears to be controlled
- 13 -
-------
mainly by the alluvial flow, although fractures in the bed-
rock may also be contributing to the transmittal of the con-
taminated water.
POTENTIAL RECEPTORS
Numerous private wells are located downgradient of the site.
Also, three organizations supply water from wells in the
Chino Basin to residential, commercial, and industrial
customers in the Glen Avon area. These are the Jurupa Com-
munity Services District, the Mutual Water Company of Glen
Avon and the Santa Ana River Water Company. Three relatively
low volume service wells operated by the Feldspar Gardens
Mutual Water Company, and located just to the southwest of
the mouth of the Pyrite Canyon, are no longer in use.
Groundwater exiting the canyon mixes with the downgradient
regional aquifer. If the contamination spreads further into
this aquifer, it could eventually contaminate the drinking
water supply wells for residents in the Glen Avon and sur-
rounding areas as well as those wells used for industrial
and agricultural purposes. An alternative water supply is
being provided by DHS to about 400 resident households
directly downgradient of the site (refer to section under
"Site History").
Groundwater exits Pyrite Canyon into the Glen Avon sub-basin
aquifer, a unit of the Chino Basin aquifer. Without reme-
diation, the potential for environmental damage is signi-
ficant, because the entire Glen Avon sub-basin aquifer as
well as parts of the larger Chino Basin aquifer could become
contaminated. Contamination of the groundwater supply in
the aquifer under the Glen Avon community could expose those
who use this water to contaminants through ingestion and, to
a much lesser extent, through dermal exposure and inhalation
from volatilization of certain chemicals.
EXPOSURE POTENTIAL
The exposure potential to heavy metals is the same as that
addressed in the earlier ROD of July 18, 1984, since they
appear not to have migrated beyond mid-canyon. However,
several organic contaminants are in the groundwater in the
lower canyon and upper reaches of the Glen Avon community
areas. TCE and chloroform are the most mobile of the
priority^pollutants onsite in groundwater, and both chemicals
have been detected in the community, thus presenting the
greatest immediate danger to community groundwater users.
TCE has a relatively low acute toxicity, but exposure to
high doses can cause central nervous system depression,
long-term neurological effects, dermatitis, and peripheral
neuropatheis. Potentials for TCE as a human carcino.gen are
at present unknown, but it is a proven animal carcinogen.
Chloroform is a volatile compound that can cause nausea,
- 14 -
-------
dizziness, and acute central nervous system depression, as
well as chronic liver and kidney damage. This substance has
been listed as a human carcinogen by EPA.
The Clean Water Act criteria, adjusted for drinking water
(EPA/540/6-85/003) suggests the one in one million carcino-
genic risk concentrations of 2.8 ug/1 (micrograms per liter)
for TCE and 0.19 ug/1 for chloroform. Based on the TCE and
chloroform levels listed earlier in this section (under
"Nature and Extent of Contamination" and Well No. FC-251A2),
the community risk level for TCE and chloroform from drink-
ing contaminated grpundwaters may appear high. Health risks
from exposure to contaminated groundwaters are expected to
vary significantly throughout the community, and relate to
the source of the extracted groundwater relative to the loca-
tion of the contaminant plume.
The other significant exposure potential is through surface
water exposure from water onsite and from upgradient water
running on the site, especially during large storm events.
This exposure potential is limited because the site is
capped, some drainage improvements have been completed, and
normal rainfall amounts are relatively small. However, this
exposure potential can be limited to an even smaller poten-
tial improving surface drainage, especially in the upgradient
areas.
ENVIRONMENTAL ASSESSMENT
Vegetation in Pyrite Canyon and surrounding hills is sparse
and typical of a coastal sagebrush community, dominated by
coastal sagebrush, white sage, and black sage. According to
a map included in the Riverside County Comprehensive General
Plan, there are no unique plant communities in the Glen Avon
area. Also, there are no endangered, rare, or threatened
animal species in the area near the Stringfellow site. Even
though several birds, mammals, reptiles, and amphibians have
been seen in the vicinity of Pyrite Canyon, no significant,
rare or unique permanent habitat in the vicinity of High-
way 60 has been observed. Occasionally, rabbits and sheep
use this grasslands area in the lower canyon as a corridor
for movement.
ENFORCEMENT ANALYSIS
On April 21, 1983, the United States and the State of
California filed a civil suit in the United States District
Court for the Central District of California. Eighteen gen-
erators, four transporters, and nine owner/operators were
named as defendants in the lawsuit (refer to July 1984 ROD).
While this litigation proceeds, and EPA continues its efforts
- 15 -
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to recover past and future costs of cleanup from potentially
responsible parties (PRPs), specific discussions with some
PRPs are being held on the early implementation actions
(EIAs) -presented in this ROD Addendum. These discussions
have focused on the design and implementation of the EIAs
and they began in the. fall of 1986. The PRPs have been given
the opportunity to perform the design and implementation of
these EIAs subject to EPA and State approval and oversight.
However, negotiations have not been successful in producing
an acceptable agreement between the EPA, State, and PRPs.
ALTERNATIVES EVALUATION
REMEDIAL OBJECTIVES
The overall objective of the RI/FS for the Stringfellow site
is to determine a final remedy that protects public health
and the environment. The following specific objectives have
been identified for the final remediation process:
1. Prevent further plume migration.
2. Prevent clean water from becoming contaminated by iso-
lation and/or treatment of the contaminated soil/waste
mixture.
3. Manage community and site area groundwater which may
adversely affect public health or the environment.
4. Route runoff and run-on to prevent surface water
contamination.
5. Prevent air emissions from the site which may adversely
affect public health and/or the environment.
6. Prevent and control air emissions of contaminated mate-
rial during the implementation of the remedial action.
7. Manage the onsit,e area to prevent direct contact by the
general public.
ALTERNATIVES CONSIDERED
A screening of 86 potentially applicable remedial technolo-
gies was performed by SAIC. Remedial alternatives were de-
veloped by compiling suitable technologies into feasible
systems to manage and control the source waste material and
the migrating contaminant plume at the site. These remedial
actions were developed and screened for control and manage-
ment of four primary types of materials: (1) uncontaminated
surface water runoff from surrounding drainage areas; (2) uncon-
taminated groundwater from areas upgradient of the site;
- 16 -
-------
(3) the contaminated soil/waste mixture; and (4) contaminated
groundwaters from beneath the site and from the downgradient
plume.
After the initial screening of all remedial alternatives for
the site, except in the "no action" alternative, the follow-
ing two remedial actions are included in all Stringfellow
remedial alternatives regardless of the specific remedial
actions implemented in upgradient or onsite areas:
1. Diversion of upgradient surface waters with a new
peripheral channel north of the original site.
2. Mitigation of the downgradient contaminated plume
using a groundwater barrier system and management
of the extracted contaminated groundwater.
This ROD will deal with only these two remedial actions and
the "no action" alternative. The final remedy will not be
selected until at least another year. These remedial actions
are consistent with all the remaining potential remedial
alternatives and can be implemented now. In the following
sections the "no action" alternative will be compared with
each alternative with respect to selection of these remedies
as early implementation actions. Early implementation ac-
tions are those actions which are part of each alternative
remedial action remaining after the FS initial screening,
and which will increase the effectiveness of the existing
system in meeting the objectives of protecting public health,
welfare, and the environment. Therefore, they are desirable
to implement as soon as possible. Since the above two re-
medial actions are included in all alternatives remaining
for detailed evaluation, they could be selected as early
implementation actions if the "no action" alternative is
rejected, and if it is determined that they will increase
the effectiveness of the current remedial actions.
1. Upgradient Surface Water Management
Southward extension of the concrete channels on the east and
west side of the site was approved in the July 1984 ROD for
this site. Partial drainage channels to divert surface water
around the site are in place to the east and west of the
original site. An effective drainage control for the run-on
water would involve completing the drainage system by con-
structing a new peripheral channel, north of the original
site, which would tie into the existing east and west drain-
age channels. Thus, this action would be consistent with
the July 1984 ROD and the alternative to install concrete
channels. This would divert surface waters flowing from the
north around the original site. Currently, some surface
water enters the waste area during heavy rainfalls, and
- 17 -
-------
increases the probability of erosion and a potential source.
of contaminated surface water. Diversion of uncontaminatedj
surface water before contact with the onsite area is pref-
erable to control of contaminated surface water after contact
since it is more effective and cheaper to manage unconlam-
inated surface waters than treat contaminated surface water.
This action would contribute significantly to meeting reme-
dial objectives 4 (Route runoff and run-on to prevent surface
water contamination) and 2 (Prevent clean water from becoming
contaminated by isolation and/or treatment of the contam-
inated soil/waste mixture) listed earlier. It would also
increase the effectiveness of the existing drainage system.
The two alternatives for upgradient surface water management
are: (Al) No action; and (A2) Diversion of upgradient sur-
face waters with a new peripheral channel at the north end
of the original site.
2. Downgradient Plume Management
The July 1984 ROD approved a groundwater extraction barrier
in the mid-canyon area with treatment of the extracted con-
taminated water at an onsite treatment plant. This alter-
native for the lower canyon area is similar to and consistent
with the July 1984 ROD action for the mid-canyon area. A
groundwater barrier, the essential elements of which are
extraction wells, would be installed in the lower canyon
(Highway 60) area. The objective of this action is to
intercept the contaminated plume at a location just north of
Highway 60 in order to (1) remove contaminated groundwater/
and (2) stop additional contaminated groundwater from moving
south into the community of Glen Avon.
This action will contribute significantly to meeting reme-
dial objectives 1 (Prevent further plume migration) and 3 (Man-
age community and site area groundwater which may adversely
affect public health or the environment) listed earlier.
The action will significantly increase the effectiveness of
the current downgradient plume management system by prevent-
ing contamination movement through the lower canyon. This
will be accomplished by creating a hydrologic barrier using
a series of extraction wells (approximately 3 to 5) installed
perpendicular to the contaminated groundwater plume. Cleanup
standards for the overall remedy will be addressed in the
Record of Decision for the final remedy following the full-
scale feasibility study.
The necessary elements of the proposed action are:
1. Interception and extraction of the contaminated
groundwater.
2. Aboveground facilities for management of the extracted
groundwater.
- 18 -
-------
3. Proper disposal of the extracted groundwater.
There are several alternative methods to accomplish each of
the above elements, as shown schematically in Figure 7. The
only disposal method being considered for this early imple-
mentation action is disposal into the existing SARI line.
This is because the existing discharge permit to the SARI
line has an ample unused volume allocation, which can be
used now. In contrast, disposal by groundwater reinjection
into the aquifer or surface discharge to Pyrite Creek would
involve many months, even several years, of preliminary work
to obtain the necessary permits. However, it is emphasized
that disposal of treated effluent by groundwater reinjection
and surface discharge are still viable options for the final
remedial alternative at the Stringfellow site. If a disposal
system other than disposal to the SARI line is selected for
the final remedial alternative, most of the improvements
built for this early implementation action can be used in an
alternative system or as part of a backup disposal system.
For the Early Implementation Action being proposed," a new
separate treatment facility was not considered. However, a
new treatment facility in the lower canyon near Highway 60
and/or expansion of the existing mid-canyon treatment plant
remains a viable option for the final remedial alternative.
Referring to Figure 7, it can be seen that elimination of
any disposal method except the SARI pipeline, and elimination
of treatment other than at the existing mid-canyon treatment
plant, have reduced the number of alternative systems possi-
ble for this early implementation action to the following:
(Bl) No action, (B2) Extraction and no treatment, and (B3)
Extraction and treatment.
ANALYSIS OF POTENTIAL EARLY IMPLEMENTATION ACTIONS
1. Upgradient Surface Water Management
a. Alternative Al; No Action. If no action is taken to
manage (divert)the upgradient surface water, this
water could reach the Stringfellow site during periods
of heavy rainfall. This water could also infiltrate
upgradient to become groundwater and migrate to the
contaminated onsite area. The existing cap over the
site is not an adequate seal to prevent surface water
percolation into the contaminated material onsite, and
there would be a possible increase of infiltration at
the site. Compared to upgradient surface water manage-
ment conditions, no action (status quo conditions) is
- 19 -
-------
t« IMC I IPS
BAM HAHR
or
fitractlon
Mil
lyStem
Icmporarjr storage
prior 10 Itnk truck
loading. Including
truck loading ttatlon
f1 i
(wet well) prior to
fifopln) up-tanyon to
•Id-canyon prelreat-
renl plant
lank truck
transport
to aid-canyon
treatment
plant
Punp station
and plpcltnt
to •Id-can/on
treaiwnt
plant
temporary storage
prior to treatment
In the to»«r.canyon
Hoy 60 vicinity
No treatment, «•.. »
eitracted water can
be dlschirged to $AR|
plptlln* without
treat-sent
Iretliient at nld-canyon
plant for rtnoval of
total toilc organlci.
Attumct that SARI will
not accept «• traded
water without treat-
ment, at least Initially
treatment at mid-canyon
plant for rtiaoval of
contanlnantt to le««ll
acceptable for surface
water dltchargt
IreatAent at aid-canyon
plant for re««*al of
contanlnantt to Icvtlt
acceptable for ground-
watcr recharge
Separat* IrcaUnent near
llwy 60 for runoval of
o> total totlc organic!.
Aitu»c« that SARI Hill
not accept extracted
water •Ithout tre*went,
at lea»t Initially
Separate treatment war
llwy (0 for removal of
contaalnanti to level*
acceptable for surface
wter discharge
Separate treatment near
llwy 60 for rewoval of
contaminants to levelt
acceptable for ground-
water recharge
Of tmufdi
lank truck trans-
port to Cktttln?
*,AR| line
Olsposel to editing
SARI pipeline at
disposal station
pelently he Ing uteJ
tfroporary storage
for flow control
end nonltorlng
purpotes, Including
truck loading
station
• Possible fulurt dls-1
ji«tal to proposed |
i SARI pipeline e.ten-1
'slon in the *lclnll/l
I Of HWI 60 and P/rilj]
temporary storage
for flow contrul
and monitoring
purport
Pipeline to point
of disposal
lewporary storage
for flow control
and Mtnltorlng
purposes. Including
truck loading .
station
I S-jrf
• p| Into
I "I I (eln
1 U grou
J iout
I s>U
S-jrface JilCl.Jfl*
I Sank truck transport
to etlstlng SARI
line
lemaor.irv storage
for flo« control
and nonltorlng
purposes
Pipeline to point
of disposal
discharge
Into P>rltt Channel
Relnjection Into
groun
-------
currently resulting in an increased amount of contam-
inated water migrating downgradient from the site. It
also increases the potential for erosion of the exist-
ing cap* and of the contaminated soil onsite. Should
significant erosion occur, it would increase potential
public exposure to contaminated runoff water and in-
crease the amount of contamination migrating from the
site into the downgradient groundwater in the Glen Avon
area. In short, taking no action poses a threat to
public health, welfare, and the environment.
b. Alternative A2; Diversion of upgradient surface waters
with a new peripheral channel north of the original
site. This proposed measure would extend the existing
east and west side concrete channels along the eastern,
western, and northern edges of the original site (Fig-
ure 8). This measure would replace the existing unlined
channel and berm system on the upper part of the site
and ensure that all surface run-on is collected and
conveyed around the site. The extensions will consist
of 600 feet on the east side, 650 feet on the west side
and 500 feet on the north side. The design of the
extended channels will be similar to that of the exist-
ing channels. The lining will consist of 4-inch thick,
unreinforced, precast concrete, or gunite with mesh
reinforcing. The channel cross-section (Figure 9) will
be trapezoidal with a horizontal base 4 feet wide, side
slopes of 1.5 feet horizontal by one foot vertical, and
a depth of 4 feet. The slope will average 0.06 ft/ft,
giving a maximum capacity of 1,750 cfs, well above the
100-year flood peak flows for the channel extensions.
Culverts will be constructed at several locations to
allow vehicle access to gates in the site's perimeter
fence.
Table 2 provides a summary of the various aspects of the two
alternatives for upgradient surface water management.
2. Downgradient Plume Management
a. Alternative Bl; No action. A significant potential
threat to public health exists because of groundwater
contamination from the site. Water exiting the canyon
mixes with the regional aquifer under the Glen Avon
community, an important drinking water supply as well
as agricultural and industrial water supply. There are
more than 200 private wells in the Glen Avon area
downgradient of the site. To date, no private wells
- 21 -
-------
NEW
CHANNEL
INLET
NEW
EAST
CHANNEL
JOIN
EXISTING
CHANNEL
FIGURE 8
LOCATION OF PROPOSED EXTENSION
OF EXISTING LINED CHANNELS
-------
original
ground
surface
4"-tMck unrelnforced concrete^
with mesh reinforcing
^ .7
I'D"
4'-0"
SECTION
FIGURE 0
TYPICAL CHANNEL SECTION
-------
Table 2
SUMMARY OF UPGRADIENT SURFACE WATER MANAGEMENT ALTERNATIVES
Alternative
Al: No action
Estimated Cost ($1.000)
0
Implementabllity
Reliability
Not reliable during
periods of heavy
rainfall.
Environmental Impact Til
Estimated
to Implement
Increases amount of
contaminated water
Migrating downgradlent.
Increases potential
public exposure to
contaminated runoff
water.
A2t New peripheral
channel north of
site
Capital - 284
OEM • 10/yr
30-yr present worth
at 10 percent
discount rate * 291
System is basic civil
works construction and
can be readily Imple-
mented. Construction is
within the existing site.
No permits or other In-
stitutional constraints
anticipated.
System is reliable,
provided channels
are cleaned
periodically.
No adverse environ-
mental Impact
anticipated
Procurement of
design contractor
and detailed
design « 3 months
Construction »
3 to 4 months
Based on mid-1986 costs
SFR141/031
-------
currently being used as a source of drinking water have
become contaminated; however, the potential will in-
crease if no action is taken and additional contaminated
groundwater will migrate into the community.
Chemical analyses of water samples taken from recently in-
stalled monitoring wells during the ongoing RI/FS approxi-
mately 2 miles downgradient of the site indicate that levels
of TCE exceed drinking water guidelines. Monitoring wells
in the lower canyon area have detected TCE levels in excess
of 500 ug/1. In addition/ water from wells in this area
contains elevated levels of chloroform/ chlorobenzene, dichlo-
robenzene, sulfates, and chlorides. Unless action is soon
initiated, these contaminants (many are known human carcino-
gens) will migrate further downgradient and contaminate por-
tions of the regional aquifer under the Glen Avon community.
This contamination will be greater in magnitude and areal
extent than presently detected in the community areas. The
spread of contaminants threatens public health and environ-
mental quality.
Further spread of contaminants in the downgradient plume
will increase the cost of the final cleanup. The additional
costs for further spread of the contaminants may include the
installation of additional monitoring wells in the community
to define the extent of the-plume, additional sampling and
analysis, additional extraction facilities, and treatment of
additional water as the result of dilution.
b. Alternative B2; Extraction and No Treatment. This is
the no treatment alternative which presumes that the
existing SARI pipeline discharge permit can be modified
through discussions with SAWPA to allow discharge of
untreated groundwater that meets the quality require-
ments of the discharge permit. The alternative includes
extraction wells, temporary storage with truck loading
station either at the well field or at the mid-canyon
treatment plant, tank truck transport to the SARI pipe-
line, and disposal to the SARI pipeline.
Major components of this alternative are described below:
Extraction system. Preliminary conceptual design anticipates
installation of approximately 3 to 5 extraction wells perpen-
dicular to the contaminated groundwater plume. The extrac-
tion wells would be just north of Highway 60 in the vicinity
of the existing LC wells. The wells might use electric submer-
sible pumps or eductor pumps. Average depth will be approxi-
mately 70 feet. Observation wells will be installed to monitor
- 25 -
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the effectiveness of the extraction wells. Appurtenances
may include automatic controls (water level actuated), flow
meter, well head security cover, concrete pad, fenced enclo-
sure, and electric service.
Temporary storage. This can be done in the vicinity of the
extraction wells, or the extracted groundwater can be pumped
up-canyon to the mid-canyon treatment plant for storage and
truck-loading (not treatment). The major reason to do the
latter is to have all the monitoring and truck loading acti-
vity occurring at the mid-canyon, treatment plant instead of
occurring also at a separate truck loading station near
Highway 60 may result in more efficient management of opera-
tions. Also, the additional storage tanks at the mid-canyon
treatment plant are more strategically located for future
flexibility in system operation. Decision on the location
of the temporary storage will be made during the detailed
design phase of this remedial action.
During the detailed design, if it is decided to use temporary
storage in the vicinity of the extraction wells, storage
tanks will be installed on concrete pads in a fenced area
near Highway 60. If the storage tanks are full, the pumps
would automatically shut off. A truck loading station would
be included. Location and layout of the facility would allow
convenient access for large tank trucks. The station would
operate possibly 8 hours/day, 7 days/week, and an attendant
would be needed.
During the detailed design, if storage at the mid-canyon
pretreatment plant is decided, construction of a pump sta-
tion and pressure pipeline to transport the extracted
groundwater from the extraction well barrier to the plant
would be required.
The pump station would be located adjacent to the storage
tank and would include a small building, pumps, automatic
pump controls, motor control center, electrical service,
piping and appurtenances.
The pipeline would be approximately 2,600 feet long, begin-
ning at the pump station and terminating at the 4-inch dia-
meter Stream C pipeline recently installed from the area of
the mid-canyon pumping station up to the mid-canyon treatment
plant. The pipeline would be aligned adjacent to Pyrite
Road at a depth of about 3 feet. Appropriate valves, con-
trols, and other appurtenances would be installed to prevent
water hammer and achieve automatic pump shutoff if the pipe-
line experiences a significant break.
The existing truck loading station could be used and no land
would have to be purchased. The mid-canyon treatment plant
parcel has adequate space to construct the additional storage
tanks.
- 26 -
-------
Tank truck transport to the SARI line. Vacuum tank trucks
under contract would load untreated extracted water from a
storage tank after the tank's contents have been sampled,
analyzed, and approved for disposal to the SARI line. Using
5,500-gallon capacity tank trucks, and assuming an average
flow of 30 gpm, approximately 250 tank loads per month would
be hauled to the SARI line.
Discharge to the SARI line. The existing SAWPA permit for
treated Stringfellow effluent allows the discharge of
0.187 mgd (approximately 5.6 million gallons/month). This
permit expires at the end of 1987. This alternative and
other alternatives being considered for early implementation
are based on. the presumption that SAWPA will renew the permit.
c. Alternative B3; Extraction and Treatment. This alter-
native is the same as Alternative B2 with the addition
of treatment at the existing mid-canyon pretreatment
plant. It includes extraction wells, temporary storage,
tank truck or pipeline transport to the mid-canyon
treatment plant, treatment, temporary storage of treated
effluent, tank truck transport to the SARI pipeline,
and disposal to the SARI pipeline.
Major components of this alternative are described below:
Extraction system. Same as in Alternative B2.
Temporary storage in the vicinity of extraction wells. Pre-
liminary conceptual design anticipates installation of tem-
porary storage tanks on concrete pads in a fenced enclosure
near the extraction wells. The tanks would have a total
capacity of approximately 65,000 gallons. If the storage
tank is full, the pumps would automatically shut off. A
truck loading station would be included which could load
tank trucks at a rate of approximately 500 gpm. Location
and layout of the facility would allow convenient access for
large tank trucks. The proposed capacity of 65,000 gallons
would provide storage time of 54 hours at 20 gpm extraction
rate allowing 5 days/week operation of the tank trucks to
the mid-canyon. If the extraction rate is at a maximum of
45 gpm, the 65,000 gallons provide 24-hour storage requiring
7 days/week tank operation.
Transport to the mid-canyon pretreatment plant. During de-
tailed design it will be decided if tank truck transport or
transport by pipeline will be used. Assuming a vacuum tank
truck capacity of 5,500 gallons, an average round trip time
of 40 minutes, and 24-hour operation for 7 days/week per
truck, one truck could carry 1,386,000 gallons/week. At
- 27 -
-------
45 gpm, the extraction wells would produce 454,000 gallons/
week. Given these parameters, one 5,500 gallon capacity
tank truck would be needed for transport to the mid-canyon
treatme'nt plant. If pipeline transport is used, construc-
tion of a pump station near the extraction wells as well as
a pressure pipeline to transport the extracted groundwater
from the extraction well barrier to the treatment plant is
required.
Treatment at the mid-canyon treatment plant. In this alter-
native the extracted water (Stream C) is treated in the mid-
canyon pretreatment plant to reduce total toxic organics.
The addition of Stream C, at 30 gpm, to the mid-canyon pre-
treatment plant would increase the volume being handled at
the plant from the present 700,000 gallons/month (Stream A,
which is the extracted water from the onsite area plus
Stream B, which is the extracted water from the mid-canyon
area) to about 2,000,000 gallons /month. The pretreatment
plant has a design capacity of approximately 130 gpm. There
is adequate unused capacity to accept the additional Stream C
volume. Plant operation may have to be modified from its
present schedule of 8 hours/day, 5 days/week, to 8 hours/
day, 7 days/week.
Temporary storage at mid-canyon treatment plant.. Additional
storage of treated effluent would be required at the mid-
canyon treatment plant to allow sufficient storage time for
monitoring and truck scheduling. Present treated effluent
storage capacity is 80,000 gallons (4 tanks at 20,000 gallons
each) . To allow for 2 days storage of Stream C at 45 gpm,
an additional 130,000 gallons of storage would be required
with associated piping and appurtenances.
^ truck transport to the SARI line. Treated effluent
handling costs from the mid-canyon treatment plant to the
SARI line disposal point are $4.75/ton ($0 .018/gallon) under
an existing contract. The tanker trucks currently make about
130 round trips/month. This would increase to about
370 round trips/month with the addition of Stream C.
Discharge to the SARI line. Same as in Alternative B2.
Table 3 provides a summary of the various aspects of the
three alternatives for downgradient plume management.
COMPARISON OF ALTERNATIVES
Table 2 provides a summary of the two alternatives being
considered for upgradient surface water management. Table 3
provides a summary of the three alternatives being considered
for downgradient plume management. Several conclusions can
- 28 -
-------
Alternative
Bit Ho action
estimated
Coat ($1.000) Imp!
lUbllltl
Ui Extraction
mj QO'
treatment
Capital I Set Questionable. It I*
to TOT uncertala iatj »**•
« tlM Wbetfcer tte
04s) i I,on total toxic organic*
to i,OT) (tTO) froB the
untreated groundwater
would Beet to*
cnealcal constituent
limitations of the
SAMP* permits.
Quest lonabla because
of SAMP* Derail
modification.
Extended Us* needed
tO deannatratS COB-
pl lance •Itl) dla-
cbarge per*It quality
requirements.
Reliability
table 3
summit or DOMURADIQIT FUME MUUCQUMT ALTERNATIVES
Environmental Impact
Regional aquifer used for municipal,
agricultural, and Industrial water supply
become severely contaaloated.
uld
Fair, foaponents ara aacbanlcally proven
and reliable Uee alternative B3 below).
However, catracted (rater TtO» Mctlog SAHFA
peratt ItBltatlona are uncertain unleaa
proven operationally for aoae ll»e.
Cooatructlon activities Bay Incraaae dust and
nolle although altlgallona eilat. Olaturbanca
of native habitat due to construction. Drill
cuttings disposal In proper Banner. Loss of
natural cover. Energy and other resources COB-
Bltted for an Indefinite period. Reduction of
groundveter supply, Mhlcb Bay be advantageous
since area baton Hlglwey 60 Is eiperlenctng a
high uater table. Monitoring and Balntenanoa
coaBllajent. Slight release of volatile
ealsslons froB atorage tank and truck loading
station. Potential of truck accident which Bay
result In spill. Increase In traffic on route
to SARI line. Slight Increase In contaBlnate
Bass carried by SARI line to Orange County.
Threat to quality of regional aquifer la sig-
nificantly diminished. The adverse Impacts
can be alnlBlied through proper planning.
eatlBsted Tlae
fubllc Health lapact to lapleaent
Spread of contaal-
nanta (aany are knoao
huaaa carcinogens)
Into domgradlent
areas threaten*
public health.
Public exposure to Bine Booths,
contaBlnanta In aot Including
groundvaUr la . perelt
reduced with tlae. obtaining
Truck accldanl/splll tie* ehlch la
•ay Increase public uncertain.
evposure riska.-
Ut btractlon
and treatswnt
Capltal*i
to iSJ
Ta*
OM*i 1.1M
to 1,111
Oood.
difficulty expected
In the acquisition of
aaall property
parcels fro* ailstlog
owners adjacent to
Granite Hill Road on
the north elde of
Highway 60. These
parcels are needed
for the nev
extraction wells and
the atorage tank near
the wells. Also,
rlghts-of-way will be
required for the
pipeline.
Oood. Coaponenta are aecnanlcally proven.
Short shutdowns will not significantly
affect action objectives. In case of
electric power failure at extraction well
aysteB, a portable generator will be
available with adequate horsepower to keep
the ayatea operating. Equlpaent breakdown
will result In only a brief shutdown
because a spare puap and accessories will
be kept on hand. Controls would be
provided to automatically shut off the
wells If the storage tank reached capacity,
and an alara would be activated. If there
la a truck breakdown, a replacement truck
should be quickly available. In the
Interim, the treated water Bay be atored.
Straaa C will be provided with only carbon
treatment, which has been a reliable
operation at the plant. During mechanical
failures at the plant, the extraction water
Bay be stored. Treated effluent should
easily Beet the quality and quantity
requlreBcnta of the existing discharge
perelt, which la expected to be renewed at
the end of 1987.
Same as that for Alternative U above. Also,
slight Increase ID carbon used at the treatment
plant. Regeneration of carbon baa offslte
potential for transportation accident with
possible spill. Commitment of resources and
energy at the treatment plant. Alao, volume of
contaminated material reduced and concentrated.
Same as that for
Alternative Bl
above.
Mine to tea
Based on Bld-1966 costs. The first cost figure cited Is for alternative with truck transport, and the second figure Is for alternative with pipe transport.
SFRMl/Oll
-------
be drawn from the tables and the analyses in the preceding
sections.
1. Alternative Al (no action) has significant adverse
environmental impacts and should be ruled out from
consideration.
2. Alternative Bl (no action) threatens public health and
the environment, and should be ruled out from
consideration.
3. Alternative B2, the no treatment alternative, is clearly
less expensive than Alternative B3. However, its impla-
ment ability is questionable because of problems in
obtaining a permit from SAWPA to discharge untreated
water into the SAJRI line mainly due to the uncertainty
of the total toxic organics- (TTOs) from the untreated
groundwater meeting the SAWPA permit limitations. A
long-term operating and monitoring record of acceptable
untreated groundwater quality may have to be estab-
lished to demonstrate compliance with the discharge
permit quality requirements before Alternative B2 can
be implemented. This would extend the estimated
implementation time for Alternative B2 beyond the
9 months reported in Table 3.
4. The decision to transport extracted groundwater from
the Highway 60 area to the mid-canyon treatment plant
by tank truck or pipeline is based upon: (1) the rate
(gpm) at which water is extracted, and (2) the length
of time that the water will be transported to the mid-
canyon plant. Lower extraction rates (e.g. 15 gpm) and
short term use of the mid-canyon plant favor the econ-
omies of truck transport. Conversely, higher extraction
rates (e.g. 45 gpm) and a longer period of use of the
mid-canyon treatment plant favor pipeline transport.
Storage, delivery, and monitoring wells associated with
the downgradient plume management EIA should be ad-
dressed in further detail during the detailed design of
the remedial action. These systems should be reviewed
during the implementation phase after the system has
been operated for a period of time to determine effec-
tiveness of operation.
5. Discussions should be initiated with SAWPA to determine
if the discharge permit can be modified to allow future
disposal to the SARI line of untreated groundwater that
meets the disposal quality requirements without treat-
ment (Alternative B2). A program could be initiated to
provide a record of water quality from the extraction
wells to determine compliance with the discharge permit
quality requirements.
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COMMUNITY RELATIONS
Based on interviews conducted with the community in Riverside
County"and Orange County in May 1986, an updated Community
Relations Plan was prepared which forms the basis for imple-
mentation of community relations activities in the area.
The July 1985 SAIC report on screening of 86 potentially
applicable technologies and the May 1986 SAIC report on the
initial screening of alternatives have been presented to the
community for comments. Separate public meetings were held
in Glen Avon and Orange County in August 1985 to present the
results of the screening of the 86 technologies. A public
meeting was held in Glen Avon on August 21, 1986 to update
the community on project related events and issues and to
obtain their feedback. A similar public meeting was held in
Orange County on September 18, 1986. In addition, monthly
progress meetings (open to the public) with the Stringfellow
Advisory Committee have been conducted by the DBS and EPA
project officials in Glen Avon.
Reports on the proposed EIAs were released to the public and
a request for public comments was advertised in Riverside
County and Orange County newspapers in February 1987. The
Stringfellow Advisory Committee meeting of February 18, 1987
was also a publicized forum for receipt of public comments
on the EIAs. However, ho comment from the public was re-
ceived on this matter during or after the 3-weeJc public com-
ment period in February 1987.
The proposed early implementation actions are consistent
with other remedial actions taken that have community support.
CONSISTENCY WITH APPLICABLE OR
RELEVANT AND APPROPRIATE REQUIREMENTS
The July 1984 ROD identified other environmental laws that
may apply to the then proposed remedial measure. Since this
ROD is an extension of and consistent with the actions se-
lected in the July 1984 ROD, the discussion on consistency
with other environmental laws is applicable to the proposed
EIAs. The purpose of the upgradient surface water manage-
ment EIA is to increase effectiveness of managing clean sur-
face upgradient of the site. No applicable or relevant and
appropriate requirements (ARARs) were identified for the
surface water management EIA.
The objective of the downgradient plume management action is
to intercept the contaminated plume at a location just north
of Highway 60 in order to (1) remove contaminated groundwater
and (2) stop additional contaminated groundwater from moving
south into the community of Glen Avon. Since the extracted
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water will not be used for public water supply the Safe Drink-
ing Water Act does not apply to this remedy. The Clean Water
Act is applicable to this EIA because discharge (pretreat-
ment) requirements must be met. Since the Santa Ana Water-
shed Project Authority (SAWPA) has the authority to dictate
what treatment requirements are necessary for discharge to
their SARI sewer line, the ARARs for this remedy relate direct-
ly to the SAWPA requirements. The SAWPA permit water quality
limitations for discharge to the SARI sewer line are listed
in Table 4. These requirements are being met at the existing
mid-canyon pretreatment plant and will continue to be met by
the recommended EIA. The spent carbon from the plant will
be, as is being done now, transported by a RCRA and DHS licens-
ed hauler to a RCRA and state licensed and EPA-approved TSD
facility for thermal destruction of the adsorbed organics.
As concluded in the July 1984 ROD based on a memorandum from
the California Air Resources Board stating that the
operation of the treatment plant will have no adverse effect
on air quality, the Clean Air Act requirements are not
applicable to the recommended EIA; however, air monitoring
may be recommended as a precautionary measure. Although the
recommended EIA is not an "RCRA alternative," onsite tanks
required for this action will be designed to comply with
RCRA Part 264 Subpart J.
Table 4
SAWPA PERMIT WATER QUALITY REQUIREMENTS
FOR DISCHARGE TO SARI LINE
Maximum
Concentration Maximum Mass
Constituent Limits (mg/1) Limits (Ibs./day)
Arsenic 2.0 3.1
Cadmium 0.064 0.1
Chromium (total) 2.0 3.1
Copper 3.0 4.7
Cyanide (total) 1.2 1.9
Cyanide (free) 1.0 1.6
Lead ~ 0.58 0.9
Mercury 0.03 0.05
Nickel 3.51 5.5
Silver 0.43 0.7
Zinc 0.7 1.1
Total Toxic Organics (TTO)
excluding PCBs and Pesticides 0.58 0.9
PCBs and Pesticides .0.02 0.03
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RECOMMENDATION
Based on Section 121 of the Superfund Amendments and Reau-
thorization Act of 1986 (SARA) and Section 300.68 (i) of the
National Contingency Plan (NCP) [40 CPR Part 300, November 20,
1985] the appropriate extent of remedy shall be determined
by the selection of a cost-effective remedial alternative
that effectively mitigates and minimizes threats to and pro-
vides adequate protection of public health and the environ-
ment. Generally, this requires selection of a remedy that
attains or exceeds applicable or relevant and appropriate
public health and environmental requirements (ARARs) that
have been identified for this specific site. Additionally,
remedial actions that permanently and significantly reduce
the toxicity, mobility, or volume of the hazardous sub-
stances, pollutants, and contaminants are given preference
over remedial actions that do not.
Considering these objectives as well as the limited scope of
the EIAs, the following two remedial actions that will in-
crease the effectiveness of the existing remedial system and
that are consistent with the remedial actions selected in
the July 1984 ROD for this site are recommended by EPA:
UPGRADIENT SURFACE WATER MANAGEMENT
Alternative A2. Diversion of upgradient surface waters with
a new peripheral channel north of the original site.
Also, based on the July 18, 1984 Record of Decision, the
existing eastern and western gunite channels will be extended
to discharge surface water to Pyrite Creek. The amount of
extension of the gunite channels would depend on the evalua-
tion currently being conducted by the State of California
DHS. DBS has estimated the capital cost of implementation
of this action, based on extension of the gunite channels to
Highway 60, as approximately $667,000.
DOWNGRADIENT PLUME MANAGEMENT
Alternative B3. Installation of a groundwater barrier system
in the lower canyon area and transport of the extracted water
to the mid-canyon pretreatment plant for activated carbon
treatment. Treated effluent would be trucked to the SARI
line for disposal. The effluent would receive additional
treatment at the POTW and then be discharged to the ocean.
Since groundwater is being extracted, treated, and disposed
of, the volume and toxicity of the contaminants will be re-
duced by this remedial action. Transport of the extracted
water to the mid-canyon pretreatment plant will be by tank
truck or pipeline, to be decided in the detailed design of
- 33 -
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this alternative and reviewed during implementation (initial
operation). The estimated cost range of each EIA is listed
below:
Capital Cost O&M Cost
($1,000) ($l,000/yr)
Upgradient Surface Water Management EIA 284 10
Downgradient Plume Management EIA (initially) 763 to 852 1,233 to 1,398
Alternative B2 should be implemented at a later date if/
based on Alternative B3 operating data, a SAWPA permit modi-
fication is obtained for direct discharge of the untreated
extracted water into the local POTW sewer, the SARI line.
The main points made in the effectiveness evaluation pre-
sented earlier are summarized below:
OPGRADIENT SURFACE WATER DIVERSION CHANNEL
o The no action alternative was rejected because of
the threat of potential public exposure to contam-
inated runoff water during very large rainfall
events, and higher volumes of contaminated ground-
water migrating downgradient from the site. Flood
control measures immediately north of the original
site are inadequate to ensure that onsite erosion
and transport of contaminated soil and water to
areas downgradient of the site could not occur
during future periods of intense rainfall. Onsite
groundwater infiltration of surface water run-on
from the northern upgradient area would result in
an increased amount of contaminated groundwater
from the site. The upgradient surface water diver-
sion channel will decrease groundwater infiltration
at the site and reduce the possibility of increased
public exposure to contaminated runoff/sediments
during future periods of heavy rainfall.
o This action is included in all remedial alterna-
tives being evaluated in detail in the feasibility
study.
o J This action is consistent with and an extension of
actions implemented as a result of the July 1984
ROD. It is simple to implement, reliable, and is
relatively inexpensive, with low maintenance costs.
o This action has community support, has no signifi-
cant adverse environmental effects, and will help
in protecting public health, welfare, and the
environment.
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DOWNGRADIENT PLUME MANAGEMENT
o The no action alternative was rejected because
findings indicate that a significant potential
threat to public health exists as a result of
groundwater contamination migrating downgradient
from the site. High levels of groundwater contam-
inants have been detected in the lower canyon
area, and migration of these contaminants into the
community groundwater downgradient must be stopped
as soon as possible. , The groundwater barrier
system will help considerably in meeting this
objective.
o A groundwater barrier system in the lower canyon
area is included in all remedial alternatives being
evaluated in detail in the feasibility study.
Transportation of the extracted water to the exist-
ing mid-canyon pretreatment plant for activated
carbon treatment was determined to be the best and
most effective way to manage this water, at least
initially.
o This action is consistent with and an extension of
actions implemented as a result of the July 1984
ROD. It has been proven to be implementable and
reliable. Since groundwater is being extracted,
treated, and disposed of, the volume and toxicity
of the contaminants will be reduced by this reme-
dial action.
o This action has community support, has no signifi-
cant adverse environmental effects, and will play
a major role in protecting public health, welfare,
and the environment.
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OPERATION AND MAINTENANCE
Upgradient Surface Water Diversion Channel; $10/000 per
year. _These costs include allowances for debris removal and
channel repair.
Downgradient Plume Management;
System Element
Item
No.
1. Groundwater extraction system,
45 gpm max
2. Temporary storage in vicinity
of extraction wells
3. Transport to the mid-canyon
pretreatment plant
Item
No. System Element
4. Treatment at the mid-canyon
pretreatment plant, 30 gpm avg
5. Temporary storage at the
mid-canyon pretreatment plant,
2 days for 45 gpm
6. Tank truck transport to the
SARI line and monitoring costs
7. Disposal to the SARI line,
30 gpm
TOTAL
Annual O&M Cost
($1,000)
26
* **
6 to 45
* **
32 to 158
Annual O&M Cost
($1,000)
224
68
694
183
1,233* to 1,398**
Pipeline transport to pretreatment plant
**
Tank truck transport to pretreatment plant
The State of California (DHS) has made a commitment to pro-
vide 10 percent of the construction and operational costs of
the recommended EIAs.
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SCHEDULE
UPGRADIENT SURFACE WATER MANAGEMENT
Complete detailed design: September 1987
Award construction contract: March 1988
Complete construction: July 1988
DOWNGRADIENT PLUME MANAGEMENT '
Complete detailed design: September 1987
Award construction contract: March 1988
Complete construction: July 1988
Begin operation of groundwater
extraction and treatment system: August 1988
FUTURE ACTIONS
ElAs IMPLEMENTATION
A detailed design of the EIAs will be performed after their
approval in this ROD Addendum. Implementation of the EIAs
is expected to occur starting in early 1988. The State of
California will pay a 10 percent cost-share of construction
and operational costs of the EIAs unless the potentially
responsible parties agree to do the design and implementation
of these actions.
FULL-SCALE RI/FS
A full-scale RI/FS was funded under the cooperative agreement
with DBS. DBS.contractor SAIC is conducting the RI/FS for
the State. The FS/ expected to be concluded in late 1987,
will identify a cost-effective remedial action or actions
for final site closure that will protect public health/ wel-
fare/ and the environment. This will include other remedial
actions in conjunction with the EIAs recommended in this ROD
Addendum..
REMEDIAL DESIGN
A comprehensive ROD for the Stringfellow site will select
the appropriate remedial action(s) for the site in mid-1988.
This will be followed by remedial design of the actions
approved in the ROD.
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REMEDIAL ACTION
Upon completion of the remedial design/ implementation of
the full-scale remedial action for final site closure will
begin in 1988. It is anticipated that the State of Califor-
nia will apply for an amendment to the cooperative agreement
to implement final site closure. The State has agreed to
provide a 10 percent cost-share for remedial action activ-
ities unless the potentially responsible parties provide
funding of these activities.
SFR141/030
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RESPONSIVENESS SUMMARY
STRINGFELLOW ACID PITS
Glen Avon, California
Reports on the proposed EIAs were released to the public and
a request for public comments was advertised in Riverside
County and Orange County newspapers in February 1987. The
Stringfellow Advisory Committee; meeting of February 18, 1987
was also a publicized forum for receipt of public comments
on the EIAs. However, no comment from the public or govern-
mental agencies was received on this matter during or after
the 3-week public comment period in February 1987.
SFR141/081
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