Laserfiche WebLink
r <br /> V <br /> Monitoring wells MW-13 and MW-14A, and vapor wells VM-1 and VM-2 bound the lateral <br /> extent of TPHg and benzene in groundwater. Until its removal in 1994, monitoring well MW-2 <br /> bound the horizontal extent to the south. <br /> The 1999, 2000, and 2001 investigations were performed to collect data for vertical <br /> characterization. The vertical TPHg extent in groundwater ranges from 14 m (46.5 ft) bgs to 20 <br /> m (66 ft)bgs. <br /> In 1999, vertical groundwater sampling was performed for MW-13, MW-14 and VM-2 (URS, <br /> 2000). TPHg concentrations in MW-13 were 540 pg/L at 16.6 m (55 ft) bgs, 1,100 pg/L at 20 m <br /> •� (66 ft)bgs, 490 pg/L at 22.5 m(75 ft) bgs, and 560 pg/L at 25.5 m(85 ft)bgs. Benzene <br /> concentrations were 240 pg/L at 16.6 m (55 ft)bgs, 430 pg/L at 20 m(66 ft) bgs, 200µg/L at <br /> �. 22.5 m(75 ft) bgs, and 240 pg/L at 25.5 m (85 ft)bgs. The maximum concentrations reported <br /> for MW 13 were in 1998, which were 10,000 pg/L. for TPHg and 4,200 p g/L for benzene when <br /> groundwater was at 15 m (49 ft) bgs. <br /> TPHg and BTEX concentrations were not detected in MW-14 during the 1999 sampling event. <br /> The maximum concentrations reported for MW 13 were in 1996, which were 11,000 pg/L for <br /> TPHg and 3,200 pg/L for benzene when groundwater was at 18 m (61 ft) bgs. <br /> The 1999 VM-2 TPHg concentrations were 29,000 µg/L at 14 m (46.5 ft)bgs and 30,000 pg/L at <br /> 18 m (59.5 ft)bgs. Benzene concentrations were10,000 pg/L at 14 m (46.5 ft) bgs and <br /> +— 9,000 pg/L at 18 m (59.5 ft) bgs. The maximum levels were detected in 1997, which were <br /> 72,000 pg/L for TPHg and 28,000 pg/L when groundwater was at approximately 17 m (56 ft) <br /> bgs. <br /> In 2000, discreet vertical groundwater sampling was performed for VM-1 and MW-13 (Ninyo <br /> and Moore 2000). TPHg and benzene concentrations were less then the detection limit at 14 m <br /> (47 ft)bgs. TPHg and benzene concentrations were 3,000 pg/L and 192 pg/L, respectively, at <br /> �.. 17 m (57 ft)bgs. The maximum contaminant levels (MCLS) were detected in 1998, which were <br /> 42,000 pg/L for TPHg and 9,600 pg/L for benzene when groundwater was at 15 m (50 ft)bgs. <br /> ` TPHg and benzene concentrations for MW-13 were less then the detection limit at 16.5 m (55 ft) <br /> bgs and at 22.5 m(75 ft)bgs. TPHg was also less then the detection limit at 19.5 m(65 ft) bgs. <br /> +- Benzene was detected at a concentration of 980 pg/L at 19.5 m (65 ft)bgs. <br /> In 2001, vertical groundwater sampling was also performed for CPT-1 (Geocon, 2001). TPHg <br /> and TPHd were only detected in the shallowest sample,between 16.5 m(55 ft) and 17 m (58 ft) <br /> w. <br /> SacGP•MistcOP120021PA,APJ81B31632894.2ab.doc 2-3 <br /> (0102A000J <br />