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Treatability Study Report and Feasibility Evaluation for In Situ Petroleum Hydrocarbon Remediation Field Maintenance Shop #24, 8020 South Airport Way Stockton. California duration of the test to maintain between 40 to 50 scfm. At the end of the test, the applied vacuum had increased to approximately 55 in. w.c. at a flow of 41 scfm. Soil vapor was effectively removed from FMS-SVE1 at applied vacuums up to approximately 70 in. w.c. during the test without significant water production. A vacuum versus flow step test was performed at each of the short duration test wells. Vacuum and flow conditions at FMS-DPE1 ranged from an initial vacuum of 115 in. w.c. to a final vacuum of 25 in. w.c. with flows ranging from 123 scfm to 49 scfm, respectively. Vacuum and flow conditions at FMS-DPE2 ranged from an initial vacuum of 150 in. w.c. to a final vacuum of 70 in. w.c. with flows ranging from 96 scfm to 50 scfm, respectively. Vacuum and flow conditions at FMS-MW5 ranged from an initial vacuum of 190 in. w.c. to a final vacuum of 258 in. w.c. with flows ranging from 13 scfm to 16 scfm, respectively. Water production was minimal during the short duration tests. Results of vacuum versus flow step testing are summarized in the Pilot Test Summary Data sheets included in Appendix F. 3.2.2. Induced Vacuum Measurements During the SVE testing at FMS-SVE1, induced vacuum measurements were recorded at five observation wells. Induced vacuum responses were observed in observation wells at a distance of 9.3 feet (FMS-DPE1), 41.3 feet (FMS-DPE2), 94 feet (FMS-MW1), 116.7 feet (FMS-MW2), and 180.4 feet (FMS-MW4) at applied vacuums ranging from 25 to 143 in. w.c., At the end of testing under steady operating conditions with an applied vacuum of 55 in. w.c., the highest induced vacuum reading of 2.75 in. w.c. was observed at well FMS-DPE1, located 9.3 feet from the extraction well. The most distant observation well with measurable vacuum (FMS-MW4), was located 180.4 feet from the extraction well, and exhibited an induced vacuum influence of 0.11 in. w.c. Induced vacuum measurements were recorded on field data sheets and summarized in the Pilot Test Summary Data sheets in Appendix F. Induced vacuum measurements are also shown in the cross-sections enclosed as Figure 4 and Figure 5. Well FMS-MW5, despite its close proximity to the test well, did not show a vacuum response. Instead, the wellhead space exhibited a positive pressure ranging from 0.2 in. w.c. to 0.5 in. w.c. This is likely due to the fact that well FMS-MW5 is not screened across the upper sand interval intersected by well FMS-SVE1, as shown in the cross-sections of Figures 4 and 5. As the water table lifted under the applied vacuum at FMS-SVE1, it likely compressed the column of air within the FMS-MW5 well head, causing a positive change in wellhead pressure. 3.2.3. Advective Air Flow Measurements During vacuum ROI testing, a 1 -liter Tedlar° bag was filled with air and attached to a peripheral well (monitoring point) to evaluate advective airflow and to verify that airflow occurred at the monitoring point(s) where induced vacuums were observed. Observed advective airflow is an indication that vapors are being conveyed toward the extraction well. In addition, this airflow will promote oxygen introduction and biodegradation of hydrocarbons in the subsurface. Advective airflow may indicate that either a) SVE/biodegradation can occur at lesser -induced vacuums than the generally accepted threshold of 0.1 in. w.c., or b) SVE/biodegradation may not occur at the generally accepted threshold vacuum of 0.1 in. w.c., if advective airflow is not measured. OTIE 17