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INFORMATION SHEET CITY OF STOCKTON AUSTIN ROAD LANDFILL FACILITY CLASS III LANDFILL SAN JOAQUIN COUNTY The City of Stockton presently owns and operates a Class III landfill about seven miles southeast of Stockton,on Austin Road. The site consists of 184 acres,of which 124 acres are for landfilling,and 43 acres are used as a borrow area. The 184-acre facility was originally opened in 1955 and is currently accepting approximately 525,000 cubic yards(150,000 tons)of refuse per year. The Discharger proposes an expansion of 143.8 acres to the facility. The expansion will develop in Phases I through IV of horizontal expansion to the south,followed by Phases V and VI of vertical expansion over the existing and new landfill areas. Liners are required for all of the new landfill footprint. The expansion shall also include: a 126 acre borrow area north of LF-1;a 13 acre composting facility; a six acre Materials Recovery Facility; a leachate treatment and holding facility; and a sedimentation basin. The first water bearing formation is approximately 70 feet below the base of the landfill,with the hydraulic gradient to the north/northeast. The beneficial uses of ground water are domestic, municipal,and agricultural. A Solid Waste Water Quality Assessment Test in 1989 found a significant ground water quality impact. The following volatile organic compounds(VOCs)were found in the downgradient monitoring wells: vinyl chloride(11 µg/1),tetrachloroethane(210 µg/1),trichloroethane(39 µg/1),and cis-1,2-dichloroethane(36 µg/1), and numerous others. This was confirmed with r further sampling. Supplemental sampling results indicated that VOCs were detected in fur California Youth Authority(CYA)wells CYA-1 and CYA-2 at levels equal to or slightly above action levels. However,confirmation sampling of the CYA wells did not detect any VOCs. Sampling at a private well at 8106A Austin Road did find VOCs, and this was confirmed by further sampling. The Discharger constructed Well No. 14 between the 8106A Austin Road well and the confirmed plume location. Well No. 14 did not encounter the plume. Additional sampling and analysis are needed to determine if the plume extends to 8106A Austin Road. A Corrective Action Plan was proposed by the Discharger on 24 April 1991 to address the chlorinated hydrocarbon impact to ground water. The plan was approved by the Board staff on 10 June 1991 Two extraction wells were installed and about 305 gpm are extracted and treated through a stripping tower. The treated water is discharged to surface water under an NPDES permit.