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<br /> September 11,2023
<br /> Brusca File No. 260-004 Anderson Barngrover Ranch
<br /> SITE DESCRIPTION AND BACKGROUND
<br /> A 1,000-gallon diesel UST was previously located on the westerly portion of an approximate 140-
<br /> acre parcel situated directly southerly of East Comstock Road and about 2,400 feet easterly of Jack
<br /> Tone Road in Linden, San Joaquin County,California. The majority of the parcel supports farmland
<br /> comprised of orchards. The UST was situated within the Anderson Barngrover farm facility,directly
<br /> easterly of an older, sizable walnut huller building and westerly of an office building (converted
<br /> residence) associated with the farm (see Plate 3). It is indicated that the UST was an exempt farm
<br /> tank and neither San Joaquin County permitting nor regulatory oversight was required or provided
<br /> for the UST removal. Following tank removal, the UST pit was backfilled for safety reasons with
<br /> soils obtained onsite.
<br /> Laboratory testing of soil samples collected at the time of UST removal revealed than an
<br /> unauthorized release(s) had occurred from the UST system; it is reported that diesel-range
<br /> petroleum hydrocarbons and related volatile organic compounds (VOCs), including benzene,
<br /> ethylbenzene,xylenes, and naphthalene,were detected in soil samples collected beneath the UST.2
<br /> The consultant that directed the UST removal and related soil sampling work (Advanced
<br /> Environmental Concepts Inc.) prepared a Soil Assessment Workplan dated December 28, 2022 for
<br /> exploratory drilling and additional soil sampling to further evaluate the nature and extent of the
<br /> petroleum hydrocarbon soil impacts attributable to the removed UST.3 The Soil Assessment
<br /> Workplan was initially submitted to the San Joaquin County Environmental Health Department
<br /> (SJCEHD) for review. The SJCEHD subsequently forwarded the case to the Central Valley
<br /> Regional Water Quality Control Board(CVRWQCB) for lead agency oversight.
<br /> Our firm implemented the investigative work outlined in the referenced Soil Assessment Workplan
<br /> earlier this year; that work included the advancement of four exploratory borings in the area of the
<br /> former UST for the collection of subsurface soil samples for laboratory analysis.4 Based on those
<br /> findings, it was determined that further site characterization was warranted, and we conducted
<br /> additional site investigation, including additional drilling for soil and groundwater sampling,
<br /> sampling of the onsite water wells, soil gas sampling, performance of a water well survey, and
<br /> comparison of site information to LTCP criteria;those results were presented in report dated June 8,
<br /> 2023.5 Our referenced June 8, 2023 report concluded that additional definition the limits of the
<br /> petroleum hydrocarbon plume at the site was necessary to address LTCP criteria. The CVRWQCB
<br /> prepared a review letter dated June 22, 2023 requiring further site assessment, including additional
<br /> borings for plume definition and collection of a soil gas sample for analysis from location SG3
<br /> where sampling was unsuccessfully attempted in May 2023 (the sampling equipment for that
<br /> 2 San Francisco Regional Water Quality Control Board Environmental Screening Levels(ESLs);July 2019.
<br /> 3 Advanced Environmental Concepts Inc., "Soil Assessment Workplan for Anderson Barngrover Walnut Huller,
<br /> 14290 E. Comstock Road,County of San Joaquin,Linden,California";December 28,2022.
<br /> 4 Brusca Associates,Inc.;"Soil Investigation,Area of Removed Underground Fuel Tank,Anderson Barngrover Ranch
<br /> Property,APN 091-030-130m 14290 East Comstock Road,Linden, San Joaquin County,California";April 7,2023.
<br /> s Brusca Associates, Inc.; "Additional Site Investigation, Area of Removed Underground Fuel Tank, Anderson
<br /> Barngrover Ranch Property, APN 091-030-130m 14290 East Comstock Road, Linden, San Joaquin County,
<br /> California";June 8,2023.
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