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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 5.3.6. Field Measurements of Vapor Concentrations VOC, %LEL (as methane), oxygen, and carbon dioxide concentrations in the extracted vapor were periodically monitored during HVDPE testing at wells FMS-MW5 and FMS-DPE1. VOC concentrations measured with the MiniRae 2000 PID ranged from 699 to 916 ppmv during the FMS-MW5 test, and 380 to 632 ppmv during the FMS-DPE1 test. VOC concentrations measured with the GasTech GT -408 ranged from 5,860 ppmv (11 % LEL, as methane) to >10,000 ppmv (28% LEL, as methane) during the FMS-MW5 test and 2,280 ppmv (4% LEL, as methane) to 4,140 ppmv (8% LEL, as methane) during the FMS-DPE1 test. Field measurements of vapor concentrations were recorded on field logs and are summarized in the Pilot Test Data sheets in Appendix F. 5.3.7. Vapor Sample Results Vapor samples collected from the extracted vapor stream at the beginning and end of HVDPE testing at well FMS-DPE1 show a decrease in TPH-g concentration from 4,700 to 1,100 ppmv, and a decrease in benzene concentration from 29 to 12 ppmv. TPH-g vapor concentrations collected for FMS-MW5 decreased from 5,900 ppmv at the start of testing to 2,400 ppmv prior to completion of testing. 1,2 -DCA was detected in the during vapor sampling at concentrations ranging from 3.0 to 3.6 ppmv at FMS-DPE1 and FMS-MW5. Vapor sample analytical results are reported in Table 4. Laboratory reports and Chain -of - Custody are provided in Appendix C. 5.3.8. Groundwater Sample Results The groundwater samples collected from the extracted groundwater stream at the beginning and end of testing at well FMS-MW5 show a decrease in TPH-g concentration from 17,000 pg/L to 15,000 pg/L. Similarly, benzene concentrations decreased from 6,300 pg/L to 5,900 pg/L over the course of FMS-MW5 testing. Groundwater samples collected from the extracted groundwater stream at the beginning and end of testing at well FMS-DPE1 show a decrease in TPH-g concentration from 19,000 pg/L to 9,900 pg /L. Benzene concentrations decreased from 2,700 pg/L to 2,100 pg/L over the course of FMS-DPE1 testing. Groundwater sample analytical results are reported in Table 3. Laboratory reports and Chain -of - Custody are provided in Appendix C. 5.3.9. Groundwater Production Rates and Drawdown To maintain drawdown in well FMS-MW5 with an applied vacuum of approximately 14 in. Hg, a groundwater pumping rate of approximately 0.8 gpm was required. Maintaining drawdown at an applied vacuum of 35 in. w.c. during the FMS-DPE1 test required pumping groundwater at approximately 2.0 gpm. Drawdown to the pump inlet was achieved and maintained for the duration of the HVDPE test in each of the test wells. Drawdown at FMS-MW5 ranged from 24.6 feet to 25.2 feet, and at FMS- DPE1 ranged from 23.6 feet to 28.6 feet bgs. Groundwater production rates and drawdown data were recorded on field data sheets and are summarized in the Appendix F. OTIE 33