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Former Exxon Service Station No. 73942 Page 3 of 4
<br /> 4444 North Pershing Avenue November 3, 2014
<br /> Stockton, California 95207
<br /> less than 3,000 pg/L. Also total petroleum hydrocarbons as gasoline were reported at or above
<br /> 20,000 pg/L in these same three wells. Based on the high concentrations of petroleum
<br /> hydrocarbon contaminants in these and other wells at this site, the EHD is of the opinion that
<br /> additional remediation is necessary before this site can be considered for closure.
<br /> Included in Semi-annual Groundwater Monitoring Report, Second Quarter 2014, were metal and
<br /> inorganic analytical results for groundwater collected on 10 June 2014 from wells MW1, MW12,
<br /> MW13, RW4, SW1, UVB-MW1, V3 and V4. All of the constituents requested by the Regional
<br /> Board except sodium, hexavalent chromium, ammonia and bromate were analyzed and
<br /> reported for these wells. It seems reasonable that the analytical results for groundwater
<br /> collected from MW12 during the June 2014 sampling event should be evaluated to determine if
<br /> any of the concentrations exceed the water quality objectives established by the Regional
<br /> Board. If any water quality objectives are already exceeded, then remediation by PersulfOx will
<br /> no longer be considered an option.
<br /> The EHD agrees to meet with responsible parties and representatives from Cardno, EMES, and
<br /> the Regional Board, as requested by Cardno and EMES to discuss current site conditions and
<br /> remedial options, with consideration to cost effectiveness, to move this case to closure. The
<br /> EHD proposes to meet with all interested parties at the EHD office located at 1868 East
<br /> Hazelton Avenue, Stockton, California 95205 on Wednesday, 3 December 2014 at 1:00 p.m.
<br /> Please respond at your earliest convenience to confirm this date.
<br /> The EHD also directs that the sensitive receptor survey, first completed in October 2001, be
<br /> updated and submitted to the EHD by 01 December 2014. Include surface water bodies,
<br /> schools, hospitals, daycares, etc., as well as domestic, municipal, industrial, and other wells
<br /> within a 2,000-foot radius of this site. Contact the Department of Water Resources, municipal
<br /> water suppliers, and nearby industries for well information, and submit any known construction
<br /> details of the wells. Perform a physical search of the area to identify all wells, including the
<br /> potential presence of a domestic well approximately six hundred feet west of the site, and show
<br /> the location of all wells on a map, relative to the location of this site.
<br /> Cardno has reported that well IP3A, a well proposed by Cardno to be an injection well for
<br /> PersulfOx, has not been sampled since 2011 because of a well obstruction. This well must be
<br /> repaired or a work plan to destroy this well, along with nested well IP3B, must be submitted to
<br /> the EHD by 24 November 2014.
<br /> One of the underground storage tanks removed from this site on 22 July 1986 was a five-
<br /> hundred-gallon waste oil tank. During the tank removal, soil samples were collected at
<br /> approximately six feet below surface grade and analyzed for total lead, halogenated compounds
<br /> by Environmental Protection Agency (EPA) method 8010, six non-halogenated volatile organic
<br /> compounds by EPA method 8015 and volatile organic compounds benzene, toluene,
<br /> ethylbenzene and total xylenes (BTEX) by EPA method 8020. The Regional Board requires
<br /> that soil samples collected during waste oil tank removals be analyzed for gasoline, diesel,
<br /> volatile organic compounds by EPA method 8260, semi-volatile organic compounds by EPA
<br /> method 8270, oil and grease by EPA method 1664A, polychlorinated biphenyls by EPA method
<br /> 8082, and Title 22 metals. Unless it can be demonstrated that these additional analyses were
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