PB98-963151
EPA 541-R98-178
March 1999
EPA Superfund
Explanation of Significant Difference
for the Record of Decision:
Stringfellow Acid Pits
Riverside, CA
7/9/1998
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AN ANALYSIS OF STATE
SUPERFUND PROGRAMS:
50-State Study, 1998 Update
Copyright© 1998
Environmental Law Institute®
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SFUND RECORDS CT»
AZ096
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION DC
75 Hawthorne Street
San Francisco, CA 94105-3901
Explanation of Significant Differences
Stringfellow Add Pits Superfund Site
3490 Pyrite Street
Glen Avon, California
L Introduction
Tliis document presents the explanation of significant differences (BSD) for a proposed
change to the remedy chosen in the second Record of Decision (ROD2) for the Stringfellow
Superfund site (the "Site"). ROD2, dated July 18,1984, addressed the installation of an cm-site
pretreatment system for contaminated groundwater resulting from past activities at the Site.
The Site is located at 3490 Pyritc Street in Glen Avon, California. The primary agencies
with responsibility for the Site are the United States Environmental Protection Agency, Region
DC (US EPA), and the California Environmental Protection Agency, Department of Toxic
Substances Control (DTSC) located in Sacramento, California. DTSC is the lead agency for the
project proposed in this BSD.
Preparation and public notice of this ESD is required pursuant to section 117(c) of the
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), 42
U.S.C. section 9617 (c). This ESD will become part of the administrative record (the
"Administrative Record") for the Site. The Administrative Record is available for review in
several repositories including the Riverside Public Library, 3581 Mission Inn Avenue, Riverside,
California, and the Glen Avon Branch Library, Stringfellow Information Center, 9244 Galena
Street, Glen Avon, California during normal library hours.
Currently, contaminated groundwater is being extracted from a series of wells located in
the original disposal area of the Site and in downgradient, contaminated zones just to the south.
The extracted groundwater is pumped to the on-site Stringfellow pretreatment plant (the "PTP")
where the water is treated to remove site contaminants. The treated water from the PTP is then
transported by tanker truck and discharged into the regional wastewater collection system,
commonly known as the Santa Ana Regional Interceptor (SARI), that serves the upper Santa Ana.
River watershed area.
Since the time ROD2 was completed, the SARI has been extended and now passes within
1.5 miles of the Stringfellow PTP. DTSC has proposed constructing a pipeline to make a direct
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connection between the FTP and the SARL A direct pipeline to the SARI line would eliminate
the tanker truck trips on the regional highways and municipal streets, and result in a significant
reduction in operating costs of the Stringfellow FTP. '
H. Background
The Stringfellow Site consists of a 17-acre area at the head of Pyritc Canyon in the Jurupa
Mountains in western Riverside County, California. The Site was operated by the Stringfellow
Quarry Company as a bulk liquid disposal facility from August 21,1956 to November 19,1972.
During that period, approximately 34 million gallons of industrial wastes including acids.
solvents, pesticides, and heavy metals were disposed of in unlined evaporation ponds. Metals
and organic compounds have percolated into the underlying groundwater atraifer, and the
contaminant plume has migrated from the Site.
In 1982, the Site was placed on the National Priorities List for remedial action under
CERCLA. In September 1983, a Tast-Track" Remedial Investigation/Feasibility Study was
initiated, and in ROD2, US EPA decided that a pretreatment plant be constructed to treat
extracted groundwater followed by discharge to a Publicly Owned Treatment Works (POTW).
Construction of the PIP was completed in December 1985, with full operation in February 1986.
The US EPA operated the PIP from 1986 until June 1996 when DTSC took over operational
control. •
The objective of the Stringfellow FTP and groundwater extraction system at the Site is to
collect and remove contamination from three groundwater influent sources: Zone 1 (the historic
waste disposal areas), Zone 2 (the mid-canyon extraction system), and Zone 3 (the lower canyon .
extraction system just north of Highway 60). Zone 1 flows (Stream A) recdve pH adjustment,
heavy metal removal, and filtration polishing treatment before being combined with Zone 2 flows
(Stream B) and Zone 3 flows (Stream C) for organic treatment in the activated carbon system.
Treated effluent from the FTP is then transported and discharged into the SARI interceptor.
Currently, treated FTP effluent is trucked to a SARI collection point in the city of Corona,
approximately 20 miles southwest of the Site along Interstate 15. Approximately 20 trucks per
day, 6 days per week, are required to transport the effluent The Santa Am. Watershed Project
Authority (SAWPA), issues and enforces the waste discharge permit for the discharge of FTP
effluent into the SARL After discharge into the SARI, the FTP effluent, along with flows from
other industrial wastewater dischargers, is men conveyed to the main County Sanitation Districts
of Orange County (CSDOC) treatment facilities in Fountain Valley where the commingled
wastewater receives additional treatment prior to being discharged into the Pacific Ocean through
an ocean outfall.
HI. Discussion of Differences
When the FTP was originally being planned, consideration was given to installing a
pipeline to connect the FTP directly to the SARI line. However, this option was rejected in favor
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of the current method of trucking the treated water to a SARI disposal point This decision was
based in large pan on the high cost involved in constructing a pipeline to the SARI line which
was then about IS miles away. Since that time, the SARI line has been extended through the
Glen Avon area and is now within 1.5 miles of the PIP. Due to the significant reduction in the
distance to the SARI line, DISC Devaluated the cost analysis of the options for transporting FTP
effluent to the SARI line. The revised cost analysis indicated that the construction of the pipeline
was now cost effective and would result in a substantial reduction in the annual operating costs
of the Stringfellow FTP. Given that the PTP will be in operation for many years into the future,
these annual cost savings would result in a significant reduction in the future cost of PTP
operation. In addition to the operational and cost benefits of a direct pipeline connection to the
SARI, the planned PTP pipeline would eliminate, approximately 5000 tanker truck trips per year
along regional highways and municipal streets.
IV. Public and Support Agency Comments
DTSC has carried out a substantial public outreach effort on this project On November
7,1997, DTSC published a Negative Declaration on the proposal pursuant to its responsibilities
under the California Environmental Quality Act (QEQA). In addition, two public meetings were
conducted to discuss the project in November 1997. Comments were received from two local
agencies and from the Community Technical Advisor. DTSC addressed the concerns posed in
these comments in their response to comments dated December 22,1997. Many of the potential
construction related impacts on the local community were considered during project planning.
These issues were appropriately addressed by incorporating specific measures into the
construction plan to minimize such impacts. Based on die DTSC initial study and die comments
received, DTSC determined that the project would not have a significant effect on the
environment
EPA contacted DTSC, the RWQCB, and the Community Technical Advisor to discuss
the proposed BSD prior to distribution of the draft Neither agency nor the Community
Technical Advisor expressed concern with the proposed change to the selected remedy as
presented in die ESD. Both agencies and the Community Technical Advisor were sent draft
copies of the ESD for comment in June 1998 and expressed support for the ESD as described
above.
V. Affirmation of the Statutory Determinations
It is the determination of US EPA and DTSC that this modified remedy continues to
satisfy the statutory requirements of cleanup under the Superfund process. Considering both the
information that has been developed during the implementation of the remedy and the proposed
changes to the selected remedy, EPA and DTSC believe that the remedy will remain protective of
human health an the environment, will comply with Federal and State requirements that are
applicable or relevant and appropriate to this remedial action, and wfll be cost effective.
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VI. Availability of Administrative Record
The Administrative Record for this Site is avauaoie lor review and comment by any
member of the public at the locations mentioned above.
DECLARATION
The selected remedy is protective of human health and the environment, attain^ federal
and state requirements that are applicable or relevant and appropriate to the remedial action, and
is cost effective. This remedy satisfies the statutory preference for remedies that reduce toxicity,
mobility and/or volume as a principal element It also uses permanent solutions to the maximum
extent practicable.
Date Keith Takata, Director
Superfund Division
US EPA, Region DC
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