SITE INFORMATION AND CORRESPONDENCE_FILE 2

Home Browse Search

/4001.1 1a Valley Motors -4 - 27 January 2014 800 E. Main St. Stockton, San Joaquin County • The contaminant plume that exceeds water quality objectives is stable or decreasing in areal extent. • Staff concluded that the Site meets all the requirements for scenario 1 of the groundwater criteria of the State Water Board's LTCP. The contaminant plume that exceeds water quality objectives (WQOs) is less than 100 feet in length. The TPH-G isoconcentration contour map and the first quarter 2013 groundwater elevation contour map are included as Figures 3 and 4. • There is no free product. • The closest water supply well or surface water body is greater than 250 feet from the defined plume boundary. The closest water supply wells are greater than 2,000' from the Site. The closest surface water was identified as McLeod Lake approximately 1 mile west of the Site. 13)The Site meets the State Water Board's LTCP's Direct Contact and Outdoor Air Exposure media specific criteria. The Site is currently a wholesale used car lot with a large garage and is zoned commercial; surrounding land use is commercial. Soil analytical data tables are included as Table 1. Petroleum concentrations in soil samples from borings SB-1 through SB-5 at 10 feet bgs were not detected using EPA methods 8015M (<1 mg/kg) and 8020 (<0.003 mg/kg), , and did not exceed the commercial or residential soil screening values from the State Water Board's LTCP. Lead was detected at 820 mg/kg at 10.5 feet below ground surface. The US EPA Commercial (Tier 1) Screening Level for soil direct exposure is 320 mg/kg. The lead was detected at 10.5-11' bgs beneath the tank pit, which is below worker safety depths. 14)The Site meets the State Water Board's LTCP's Petroleum Vapor Intrusion to Indoor Air criteria for scenario 3, with a 10' bioattenuation zone, benzene concentrations in groundwater are less than 100 ug/L, and concentrations of petroleum hydrocarbons in soil are less than 100 mg/kg. Off-site soil gas sampling was not performed. Soil contamination does not extend off the property and groundwater is not impacted by petroleum in off-site wells. 15)Public participation through distribution of a Fact Sheet was performed in March, April and May 2014. The public participation period ran from 2 March through 2 May 2014 with no comments received. 16)The remaining 11 Site wells were destroyed under SJCEHD permits and all wastes removed 24 September 2014.