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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 Advective airflow was observed in all the monitoring points with induced vacuums greater than 0.1 in. w.c. The greatest advective airflow recorded during testing of FMS-SVE1 was in well FMS-DPE1. At an extraction wellhead vacuum of 60 in. w.c. and an induced vacuum of 2.75 in w.c. in well FMS-DPE1, a 1 -liter Tedlar® bag attached to the wellhead deflated in 38 seconds (airflow of 1.58 liters per minute [L/min]). At FMS-MW4, the most distant well with a measurable vacuum response, a 1 -liter Tedlar° bag attached to the wellhead deflated in 4 minutes and 40 seconds (airflow of 0.21 L/min). Please see the Pilot Test Summary Data sheets in Appendix F for advective airflow measurements in seconds and in L/min in the observation wells. 3.2.4. Field Measurements of Vapor Concentrations During the SVE testing at well FMS-SVE1, the extracted soil vapor was monitored with a hand- held PID and a GasTech GT -408 multi -meter. The VOC concentrations measured at FMS-SVE1 using the MiniRae 2000 PID (calibrated with 100-ppmv isobutylene) decreased from 272 ppmv at the beginning of testing to 235 ppmv at the end of testing. Readings collected using the GT -408 meter decreased from 1,980 ppmv (2% LEL, as methane) midway through the testing to 787 ppmv (2% LEL, as methane) at the end of testing. Vapor concentrations measured in the field were recorded on field logs and are summarized in the Pilot Test Summary Data sheets included in Appendix F. 3.2.5. Vapor Sample Results In addition to the field monitoring, two Tedlar® bag samples were collected from FMS-SVE1 for laboratory analysis at the start and end of the SVE test. TPH-g decreased from 1,100 ppmv in the initial sample to 750 ppmv in the final sample. The benzene concentration in soil vapor decreased from 11 ppmv to 6 ppmv over the course of testing at FMS-SVE1. A Tedlar® bag sample was collected at each short duration test well prior to completion of the testing. TPH-g results were 1,100 ppmv for FMS-MW5, 1,100 ppmv for FMS-DPE1, and 120 ppmv for FMS-DPE2. The soil vapor analytical results for testing at are summarized in Table 4. The laboratory analytical reports and chain -of -custody documents are provided in Appendix C. 3.2.6. Radius of Influence for Vapor Extraction Induced vacuum measurements collected from the observation wells during the SVE test performed at FMS-SVE1 have been plotted on versus the distance from the extraction well (Graph 1). The ROI determination method, referenced in this document as the 1% method," defines the ROI as the radial distance corresponding to a practical fraction of the observation well vacuum to the test well vacuum (0.01 or 1 %) as interpolated from the fitted distribution line plotted against radial distance from the extraction well on a semi -log graph (LaGrega, 1994). The induced vacuum measurements collected from the observation wells during SVE testing from well FMS-SVE1 have been expressed as a fraction of the test well vacuum of 55 in. w.c. and plotted versus the distance from the extraction well (Graph 1). Based on the plot, the ROI is depicted at 60 feet (Figure 6), as defined by the 1% method. The induced vacuum results at FMS-MW5, as discussed in Section 3.2.2, were omitted in the analysis of SVE ROI because of the location of the screened interval. OTI E 18