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it Public Works, Stockton - 2 - 9 September 2022 hydrocarbons above reporting limits. As such, existing data appears sufficient to conclude that the Site release consisted of only petroleum hydrocarbons. I 2. Site conditions meet three of the four criteria (a, b, and d) of LTCP Groundwater Media-Specific Class 2: (a) the maximum extent of petroleum hydrocarbon impact to groundwater above water quality objectives is less than 250 feet in length, (b) there is no free product, and (d) maximum dissolved benzene and methyl tertiary butyl ether (MTBE) concentrations are less than 3,000 micrograms per liter (ug/L) and 1,000 ug/L, respectively. There are two public water supply wells located within 1,000 feet of the defined extent of the Site plume, and thus criterion c is not met. California Water Service Company (CalWater) wells are located approximately 580 feet south and 990 feet northwest of the Site. However, these wells are listed as inactive and are located up- and cross-gradient, respectively. As such, risk to human health and safety and the environment from the Site release is low, and Site conditions meet LTCP Groundwater Media-Specific Class 5 criteria. A proposal for a new/revised remediation approach is not necessary at this time. 3. The Site remains an active fueling facility. There are an office building and a maintenance shop located immediately north and south of the Site source area (former USTs), respectively. Dissolved benzene greater than 1,000 ug/L extends to or under the office building to the north. Well MW-2, which currently contains 2,800 ug/L benzene, is approximately 30 feet from both the office and maintenance buildings. Additionally, soil collected from the well OW-7 borehole, located immediately adjacent to the north side of the maintenance building, contained up to 9,400 milligrams per kilogram (mg/kg) total petroleum hydrocarbons (TPH; combined TPH as gasoline and as diesel) at 5 feet bgs, and 5,480 mg/kg TPH at 10 feet bgs. Based on these data, Central Valley Water Board staff believe an unacceptable vapor intrusion health risk may exist, and thus the active fueling facility exemption is not met. Soil gas sampling is needed near the office and maintenance buildings to properly evaluate the vapor intrusion risk. 4. Site conditions meet LTCP Direct contact and Outdoor Air Exposure criteria. Benzene and ethylbenzene concentration in shallow soil are below thresholds established in Table 1 of the LTCP. While no historical shallow soil naphthalene data exists for the Site, the risk from naphthalene is low due to the current Site usage which includes active fueling. Additionally, the likelihood of direct contact with soil is low as the Site property is covered entirely with asphalt or concrete. 5. By 11 November 2022, please submit a work plan for the installation and sampling of permanent soil gas wells to evaluate vapor intrusion risk to the office and maintenance buildings located immediately north and south of the Site source area. Central Valley Water Board staff recommends installation and sampling of