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S E C 0 R
<br /> Attachment 2 �, I
<br /> Site History
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<br /> MW-62UA, MW-63A, MW-64B, and MW-65A) on January 21 through 29, 2003 Results
<br /> and findings of assessment activities are presented in the SECOR's Site Assessment
<br /> Report, dated March 5, 2003 I q�
<br /> During March of 2003, a 1,000-gallon transmix (tank ID 1842-6) underground storage
<br /> tank (UST) was removed and selected soil samples were collected from the tank pit
<br /> area Results of soil sampling indicated moderate levels of petroleum hydrocarbons
<br /> along the sidewalls of the tank pit
<br /> On September 3, 2003, Cascade completed 12 soil borings (C-3 5, C-4 5, C-6, C-8, D-4,
<br /> D-5, D-6, D-9, F-9, H-9, J-8, and K-8) Results of the 2003 offsite assessment indicate `
<br /> that concentrations of MtBE, tertiary amyl methyl ether (TAME), TPHd, and TPHg in t
<br /> groundwater are above water quality objectives (WQO's) in several offsite locations
<br /> Groundwater concentrations of MtBE, TAME, TPHd, and TPHg appear to be undefined '
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<br /> in the area around boring C-8 MtBE appears to be undefined to the north and northeast
<br /> of the site Groundwater and soil concentrations of TPHd and TPHg appear to be 3 5�
<br /> defined in the areas around previous borings NSB-1, NSB-3, NSB-6 and NSB-8, and
<br /> MtBE appears to be defined in the areas of previous borings NSB-1 and NSB-3 ;l
<br /> Although a low concentration of TBA was detected in the groundwater from K-8, existing ,
<br /> . wells MW-52A, MW-54 and MW-55 were below laboratory detection limits for TBA in
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<br /> June 2003
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<br /> On September 4, 2003, offsite Groundwater monitoring wells (MW-53A, MW-57A, MW-
<br /> 58A, and MW-59A) were destroyed by Cascade Monitoring wells were destroyed in
<br /> accordance with SJC-EHD well standards for well destruction '
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<br /> Between October 29, 2003 and October 31, 2003, SECOR supervised, Cascade during
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<br /> the advancement of 17 soil borings (TS-1 through TS-8, TS-10 through TS-17, and TS-
<br /> 19) located in the tank farm High levels of TPHg, TPHd, and benzene, toluene, ethyl
<br /> benzene, total and xylenes (BTEX) were detected in boring samples collected near the
<br /> capillary fringe High levels of TPHg, TPHd, BTEX, MtBE, tertiary butyl alcohol (TBA),
<br /> TAME, and lead were detected in shallow groundwater samples Groundwater �.
<br /> analytical results and field observations indicated the presence of SPH in the area
<br /> between aboveground storage tank (AST) #131 and AST#139 "
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<br /> Between December 1, 2003 and December 18, 2003, Cascade installed 65 groundwater kre
<br /> oxygenation wells (OW-1 through OW-65) to an approximate total depth of 20 feet with a Zvi
<br /> screening interval of approximately 2 feet The boring samples collected near '
<br /> groundwater monitoring well MW-11 reported moderate to high detections of TPHg,
<br /> TPHd, benzene, ethyl benzene, total xylenes, MtBE, and total lead in samples collected
<br /> at the capillary fringe The detections appear to be consistent with groundwater
<br /> monitoring well MW-3UA detections
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