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S E C Q R -
<br /> **Awl ..i
<br /> 7-Eleven Store#14117
<br /> Corrective Action Plan
<br /> October 12, 2007
<br /> Page 2
<br /> concentrations of 12.5 milligrams per kilogram (mg/kg) (GP-17@20'), 42,900 mg/kg (GP-
<br /> 15@15'), and 234 mg/kg (GP-14@10'), respectively (Table 2).
<br /> On May 13 and 14, 1999, four groundwater monitoring wells (MW-1 through MW-4) were
<br /> installed to 25 and 30 feet below ground surface (bgs) (Table 1). Benzene, TPHg, and
<br /> MtBE in soil were reported at maximum concentrations of 2.89 mg/kg (MW-3-15'), 429
<br /> mg/kg (MW-3-15'), and 0.119 mg/kg (MW-4-20'), respectively (Table 2).
<br /> On October 30, 2001, three groundwater monitoring wells (MW-5, MW-6, and MW-7) were
<br /> installed to 20 feet bgs (Table 1). TPHg, benzene, toluene, ethylbenzene, xylenes (BTEX),
<br /> and MtBE in soil were not detected above laboratory reporting limits, except for 0.006
<br /> mg/kg total xylenes (MW-7@20') (Table 2). Selected halocarbons also present in the soil
<br /> samples indicated possible dry cleaner plume contributions (IT Corporation, 1999).
<br /> On August 14, 2003, deep groundwater monitoring well (MW-8) and one soil boring (SB-1)
<br /> were advanced onsite. SECOR summarized this assessment in the February 27, 2004
<br /> Additional Site Assessment Report and Fate and Transport Model, which also presented
<br /> calculations of the lateral migration of dissolved MtBE in groundwater.
<br /> Per the request of the SJCEHD, groundwater monitoring and sampling is coordinated with a
<br /> former Exxon site (currently a USA Gasoline station) immediately east of the 7-Eleven site.
<br /> On July 22, 2004 , SECOR submitted a proposal for a Field Test Program for Evaluation of
<br /> Oxidation Capacity of Groundwater to the RWQCB. The RWQCB conditionally approved
<br /> the proposal in a letter dated October 4, 2004.
<br /> On July 27, 2004, SECOR submitted a Work Plan for Additional Offsite Assessment to the
<br /> SJCEHD. The work plan was approved by the SJCEHD in a letter dated August 23, 2004.
<br /> The work plan proposed the installation of two offsite groundwater monitoring wells (MW-9
<br /> and MW-10), advancing three offsite soil borings (GP-1 through GP-3), two offsite CPT
<br /> borings (CPT-2 and CPT-3) and one onsite CPT boring (CPT-1).
<br /> Between April 26 and April 28, 2005 SECOR supervised the installation of oxygen injection
<br /> well 1-1 and the advancement of soil borings GP-1, GP-2, and CPT-1 through CPT-3 by
<br /> Gregg Drilling and Testing. With the exception of 4.0 micrograms per liter (Ng/L) of MtBE in
<br /> CPT-3 (CPT-3-70') the lateral extent of deep groundwater contamination was defined to the
<br /> northeast and east. The lateral limits of shallow contamination in soil and groundwater was
<br /> defined to the north, west, and southwest of the site. Proposed groundwater monitoring well
<br /> MW-10 could not be installed due to the presence of underground utilities around the
<br /> proposed location. Access to install proposed well MW-9 was not granted by USA Gas,
<br /> therefore MW-9 was not installed. SECOR submitted the Additional Site Assessment and
<br /> Site Conceptual Model report to the SJCEHD on September 30, 2005 summarizing the well
<br /> installation and assessment activities.
<br /> On December 2 and 16, 2005, SECOR conducted oxygen capacity testing into well 1-1 as
<br /> outlined in the July 22, 2004 Field Test Program for Evaluation of Oxidation Capacity of
<br /> 14117 CAP 10-12-07.doc SECOR Intemational,Inc.
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