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Site No: 11192
<br /> IT collected quarterly groundwater samples from wells MW-5 through MW-7 on
<br /> March 9, 1992 (IT, 1992c). Although wells MW-1, MW-3, and MW-4 were still dry,
<br /> IT noted that the wells served as pressure monitoring points during the S VE pilot test and
<br /> recommended leaving the wells in place if an SVE system was to be installed in the
<br /> future. Benzene (6.2 ppb) and ethylbenzene (0.5 ppb) were detected in samples taken
<br /> from well MW-5, located on the east side of the former motor oil UST complex
<br /> (Table C-3).
<br /> Alisto collected groundwater samples on June 19, September 18, and December 9, 1992;
<br /> March 11, June 15, September 15, and December 22, 1993; and April 1, 1994 (Alisto,
<br /> 1992a, 1992b, 1993a, 1993b, 1993c, 1993d, 1994a, 1994b). Monitoring wells MW-3
<br /> and MW-4 were dry until the June 15, 1993, sampling event. TPH-G at 2,300 ppb was
<br /> detected in well MW-3 in December 1993, as well as BTEX (31 ppb benzene, 6.5 ppb
<br /> toluene, 120 ppb ethylbenzene, and 220 ppb xylenes; Table C-3). TPH-G (up to
<br /> 340 ppb) and BTEX (up to 2.6 ppb benzene, 1.3 ppb toluene, 30 ppb ethylbenzene, and
<br /> 43 ppb total xylenes) were detected in groundwater samples collected from well MW-7
<br /> in April 1994 (Table C-3). Alisto (1994b) indicated the groundwater flow direction
<br /> beneath the site was toward the north, consistent with previous determinations.
<br /> BP informed the San Joaquin Environmental Health Department that they planned to
<br /> sample monitoring wells MW-1, MW-4, MW-5, and WtW-6 on a semi-annual basis in
<br /> a cover letter to the February 3, 1994, Groundwater !Monitoring and Sampling Report
<br /> (BP, 1993).
<br /> 3. Regulatory Status and Other Issues
<br /> Site 11192 has a case file with the local regulatory oversight agency (San Joaquin
<br /> County, Public Health Services, Environmental Health Division). The file contained
<br /> UST permit applications from 1988 to 1992, tank fee information, tank tightness test
<br /> results, documentation concerning the removal of the USTs in 1991, and agency
<br /> sampling event reports dated Pune 15, September 15, and December 22, 1993. The file
<br /> also contained an UST release report filed on July 20, 1989, after the soil gas survey
<br /> discussed in Section 2 (San Joaquin, 1989). On January 28, 1992, the county issued a
<br /> Notice to Abate because "wash" solution was being discharged into a storm drain at the
<br /> site without a permit (San Joaquin, 1992). There is no evidence in the file of any
<br /> followup actions, either by BP or the county.
<br /> On March 12, 1993, the county asked BP to send them a workplan to either destroy or
<br /> use monitoring wells MW-1, MW-3, and MW-4 by April 15, 1993 (San Joaquin, 1993).
<br /> No workplan concerning BP's plans for these monitoring wells was found in the files
<br /> available to EMCON.
<br /> 8/'COs/RPT/I1192RFr.d07-94/LAM/1b:5 Rev. 0, 12/27/94
<br /> 0952-090,03 5
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