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1 09 September 2002 ' AGE-NC Project No. 98-0450 Page 4 of 6 1 gradient from the former dispenser system and the former UST area. ' Table 1 lists the screen intervals for monitoring wells BMW-1 through B1\4W-5 and MW-5 and the assumed screen intervals for monitoring wells BMW-1 and BMW-2. With the exception of MW-5, the wells were screened across the ground water table; analytical results obtained from these wells ' should be representative of the dissolved hydrocarbon concentrations in the shallow ground water. t3.2_ LABORATORY RESULTS OF GROUND WATER SAMPLES ' TPH-g was detected in three of the six ground water samples collected at the site at concentrations ranging from 350 micrograms per liter (Ag/1) in sample MW-5 to 6,400 gg/l in sample BMW-4 (former UST area). ' Benzene was not detected in the samples analyzed; the other BTEX compounds were detected at various concentrations with the highest concentrations occurring in BMW-4 (33 µg/1 of toluene). lie MTBE was detected in samples BMW-2 and MW-5 by EPA method 8260 Modified at concentrations of 9.2 µg/l and 110 gg/l, respectively. ' The Iaboratory report(MCI Laboratory I.D. No.0206031-01 to 06)),Quality Assurance andualit Q Y Control Data(QA/QC) and chain-of-custody forms are presented in Appendix B. The results of the ' analyses are summarized in Tables 2 and 3. ' 3.3. SOIL-VAPOR EXTRACTION The SVE/IAS system utilizing the vacuum blower operated at varying rates during the observation ' period. The duration of operation was recorded with an hour meter and recorded on field logs; the system only operated a total of 1186 hours over the reporting time, due to electrical fuse failures and limited hours of operation to conform with the City Of Lodi Municipal Code. Extraction flow rates were measured and calculated to range from 40 to 55 cubic feet per minute (cfrn). An induced vacuum of approximately 12 inches of water was typically measured in the piping between the blower and extraction wells. Utilizing a PID, hydrocarbon concentrations were measured in parts per million (ppm) at regular ' intervals at the SVE inlet, however a general concentration trend was not established from the PID • field measurements. Operational field measurements of the SVE unit are summarized in Table 4. ' Hydrocarbon concentrations (TPH-g) detected in influent soil-vapor samples were as high as ,' Advanced GeoEnvironmental,Inc.