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ARCO Products Company 3 ARCO Service Station#4493,205 North Center Street.Stockton,CA July 7,1999 compound) by EPA Method 8015/8020 and fuel oxygenates and volatile organic compounds by EPA Method 8260A. Additionally, one sample from each boring was analyzed for lead by EPA 6010a. TPH-g had reported concentrations of 1.80 mg/kg and 1.56 mg/kg in soil samples MW-4@20'and MW-4@25', respectively. Benzene had a maximum concentration of 0.118 mg/kg (MW-4@25'). MtBE had reported concentrations of 0.345 mg/kg (MW-3@25') and 1.52 mg/kg (MW-4@25'). Lead had reported concentrations of 12.3 mg/kg and 141 mg/kg in soil samples MW-1 @ 10'and MW-2@ 10', respectively. TCE and PCE were reported as nondetect. Soil analytical results are presented in Table 1. Field and laboratory procedures are presented as Attachment C. Certified analytical reports and chain-of-custody documentation are presented as Attachment D. • Groundwater Monitoring Well Development, Sampling, and Surveying. After installation, the groundwater monitoring wells were developed by rigorously surging over the length of the screen interval and by purging ten casing volumes of water. Groundwater samples were collected from the newly installed groundwater monitoring wells on February 16, 1999. Groundwater samples were analyzed for TPH-g and BTEX by EPA Method 8015/8020 and fuel oxygenates and volatile organic compounds by EPA Method 8260A. TPH-g was reported in two wells at concentrations of 231 ppb (MW-1) and 15,000 ppb (MW-4). Benzene was reported in two wells at concentrations of 1.35 ppb (MW-1) and 503 ppb (MW-4). MtBE was reported in monitoring wells MW-3 and MW-4 at concentrations of 7.06 ppb and 9,990 ppb, respectively. TBA, TAME, DIPE, and EtBE were reported as nondetect in all wells. TCE was reported in three wells at a maximum concentration of 433 ppb. PCE was reported in well MW-2 at 2.50 ppb. Groundwater analytical data is presented in Table 2 and is shown on Figure 2. Field and laboratory procedures are presented as Attachment B. Groundwater sampling parameters are included on the field sheets in Attachment E. The wells were surveyed to mean sea level by Morrow Surveying, a licensed surveyor. Attachment F contains the surveyor's site plan showing the locations and elevations of the wells. • Groundwater Flow Direction. Depth to groundwater at the site ranged from 13.35 feet bgs to 14.64 feet bgs. Based on monitoring data collected on February 16, 1999, groundwater flow was to the east-northeast at 0.008 ft/ft and is shown on Figure 3. 76600-022-02/well install