SITE INFORMATION AND CORRESPONDENCE

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S� t CLEANUP AND ABATEMENT ORDER NO. 5-00-700 • 2 FLAG CITY CHEVRON 6421 CAPITOL AVENUE LODI, SAN JOAQUIN COUNTY Maximum concentrations of soil and groundwater contamination from tank pit sample TPHg TPHd Benzene Toluene Ethyl benzene X lenes Soil m 1,500 NA 81 140 26 180 Water 18,000 1,400 230 300 160 860 4. In July 1996, three groundwater monitoring wells were sampled, and all samples were less than detection limits for TPHg, TPHd, and benzene, toluene, ethyl benzene, and xylenes (BTEX) constituents. Although TPH was non-detect at the site, methyl-tertiary-butyl ether(MtBE)was identified at 310 µg/1 in monitoring well MW-1, near the underground storage tanks (USTs). MtBE was also identified up to 3.7 µg/1 from two nearby monitoring wells. 5. Subsequent soil and groundwater investigations were completed, and four additional monitoring wells were installed. Eight groundwater sampling events have been completed between July 1996 and June 1999. Groundwater samples were found to contain up to 480 µg/1 of TPHg, 1,500 µg/1 of TPHd, and 1,600 µg/1 of MtBE. 6. A Small Public Water System (Transient Water System) well at Rocky's Restaurant, 14659 Thornton Road, was sampled in February, April, June, and December 1999, and MtBE was identified up to 18 µg/l. 7. The California Department of Health Services Drinking Water Action Level for MtBE is 13 gg/l, and the Secondary Maximum Contaminant Level for taste and odor is 5 µg/1. 8. MtBE has also been identified in monitoring wells located west of Flag City Chevron at the Three B's Truck Plaza, 14749 Thornton Road in Lodi. The Three B's Truck Plaza, formerly owned by Richard Bokides and his two brothers, also has an active investigation for petroleum hydrocarbons, however MtBE has not been identified in the area of the former USTs at the Three B's site. 9. Two municipal wells identified as Flag City Well #1 and #2 are about 1,600 feet and 700 feet southeast of the Flag City Chevron underground storage tanks site, respectively. The Flag City wells are Non-Community Water System (Non-Transient Water System) wells that provide water to Flag City businesses east of Thornton Road. A groundwater analysis for petroleum hydrocarbons has not been provided for these wells. While both the Flag City wells are currently upgradient from Flag City Chevron,the well screens are set below the MtBE contamination and therefore could induce flow of contaminated groundwater to the well. The wells are used daily at an estimated flow rate of 1,000 gallons per minute. 10. On 24 September 1999, on behalf of the Discharger, Advanced GeoEnvironmental,Incorporated (AGE), submitted a Remedial Investigation/Feasibility Study Work Plan (Workplan) to the County for continued investigation of petroleum hydrocarbons. The County approved the Workplan on 6 October 1999; however, the Workplan has not been implemented to date. AGE is scheduled to complete quarterly monitoring of all monitoring wells and water supply wells by late February 2000.