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CLOSURE REQUEST REPORT Section No 2 0
<br /> Former American Forest Products Company 07/31/01
<br /> 2901 West Lane Page 2-2
<br /> Stockton California
<br /> Is.
<br /> gallon diesel tank, and 26 feet below grade at the location of the former 500-gallon waste-oil tank (Figure
<br /> 4) Excavation of impacted soil and construction of the on-site bioremedtation treatment cell was
<br /> conducted The excavation was backfilled with clean silty-sand from a local quarry, and capped with
<br /> asphalt Approximately 2,050 cubic yards of soil and associated material was disposed in November
<br /> 1990 As required by the R-WQ-CB—Ft uee d onitoring wells were abandoned, and four new wells
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<br /> (DMW-1 through DMW-4) were installed during July 1990 During June through November 1990, the
<br /> bioremediation cell operated to remediate excavated soil In March 1991, a quarterly monitoring report
<br /> was issued, which documented groundwater monitoring performed at the four new wells during August
<br /> and December 1990(Dames& Moore, 1991a)
<br /> In January 1991, PHS-EHD requested closure of the remaining underground piping area associated with
<br /> the previously removed USTs, and in April, Dames & Moore submitted an application to PHS-EHD for a
<br /> permit to close the UST-piping area (Dames & Moore, 1991b) In May 1991, PHS-EHD approved the
<br /> closure application for the fuel pipeline, and during the summer of 1991, the under r i in was
<br /> excavated and decontaminated In addition, approximately 150 cubic yards of soil in the area of the
<br /> underground fuel pipeline was excavated,removed, and disposed Site restoration included backfilling of
<br /> the excavation with pea gravel and capping with asphalt Dames & Moore submitted a quarterly
<br /> monitoring report to RWQCB, documenting groundwater monitoring performed in March and July of
<br /> 1991 (Dames & Moore, 1992a)
<br /> In May 1992, a Site Remediation Report was submitted to RWQCB and PHS-EHD (Dames & Moore,
<br /> 1992b) The report described in detail the soil and groundwater investigation, the soil excavation and
<br /> remediation in the area of the former USTs, and the remedial activities at the fuel pipeline
<br /> In December 1993, management of the site was reassigned to PHS-EHD At the request of the PHS-
<br /> EHD, the RWQCB reviewed the site file, and in a letter dated December 10, 1992, the RWQCB stated
<br /> that either additional soil remediation be conducted, or a feasibility study be prepared in order to assess
<br /> potential groundwater impacts The letter also stated that annual monitoring of groundwater wells was
<br /> required until site closure was approved
<br /> In January 1994, the PHS-EHD defined a soil cleanup level of 100 ppm, and stated that quarterly
<br /> groundwater monitoring was required until cleanup was deemed complete The PHS-EHD also stated
<br /> that a work plan to assess soil contannunation and conduct groundwater monitoring was required On
<br /> August 1, 1994, a Draft Amended Request for Closure was issued to PHS-EHD (Dames & Moore,
<br /> 1994a) A five-year monitoring program followed by closure was suggested, with the condition that
<br /> groundwater levels remain lower than 50 feet below surface level In an August 1994 letter, PHS-EHD
<br /> required (1) a feasibility study for reducing soil contamination to background levels at depths up to 35
<br /> feet, (2) additional soul borings, and 3) the installation of a monitoring well downgradient of the former
<br /> waste oil tank Dames &Moore subrmitted a work plan to PHS-EHD in compliance with the August letter
<br /> that described the proposed soil and groundwater investigations (Dames & Moore, 1994b) Dames &
<br /> Moore prepared a Technical Evaluation in November 1994, which provided an assessment of soil
<br /> remediation options (Dames &Moore, 1994c)
<br /> In March 1995, the PHS-EHD required the continuation of quarterly water level monitoring, annual
<br /> groundwater monitoring, and submittal of a work plan for the installation of a soil remediation option, as
<br /> described in the Technical Evaluation In May 1995, Dames & Moore submitted an addendum to the
<br /> work plan to meet the requirements of PHS-13141) A soil and groundwater investigation was conducted in
<br /> May 1995, and included the installation of two soil bonngs and one groundwater monitoring well
<br /> (DMW-5)
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