ARCHIVED REPORTS XR0001261 - Laserfiche WebLink

Home Browse Search

t the highest concentrations of TPHG, STEX, and MTBE EMCON evaluated third quarter data and selected wells MW-4 and MW-6 to be analyzed for these oxygenates Well MW-4 contained 58 micrograms per liter of MTBE No other oxygenates were detected in the samples from wells MW-4 and MW-6 (see Table 2) The remediation system was started up on January 24, 1997 The remediation system consists of a King, Buck and Associates MMC-5A Catalytic Oxidizer rated at 100 cubic feet per minute The remediation system is connected to vapor extraction wells VW-4 through VW-13 The system was operational for 35 percent of the time and extracted a total of 1,411 pounds of TPHG during the fourth quarter The low uptime was due to power failures in the local area from adverse weather A cumulative amount of 9,095 pounds of TPHG has been removed since commencing SVE activities (see Table 5) Figure 5 presents cumulative mass of TPHG removed versus time and TPHG extraction rate versus time Vapor extraction wells VW-10, VW-11 (adjacent to the former underground storage tank complex), and VW-12 (adjacent to pump islands) are still contributing to influent soil vapor petroleum hydrocarbon concentrations The remediation system has been extracting soil vapors from these wells since the other vapor wells provided minimal hydrocarbon concentrations EMCON, on behalf of ARCO, will continue to operate, maintain, and optimize the remediation system Monitoring data indicates that Benzene is declining in influent vapor concentrations, therefore, EMCON will evaluate suspending vadose remediation In situ dissolved oxygen (DO) levels were not measured due to field equipment malfunction EMCON, however, used a field kit to obtain ranges for DO, and all DO levels in the wells ranged between 0 and 2 milligrams per liter • ATTACHMENTS: • Table 1 Groundwater Monitoring Data • Table 2 Groundwater Analytical Results for Oxygenates • Table 3 Operational Uptime Information of Soil Vapor Extraction System • Table 4 Flow Rates and Analytical Results of Air Samples • Table 5 Extraction and Emission Rates • Table 6 Vapor Extraction Well Status • Figure 1 Site Location Map • Figure 2 Generalized Site Plan • Figure 3 Groundwater Contour Map (November 17, 1997) • Figure 4 TPHG Concentration Vs Time • Figure 5 Extraction Rate and Cumulative Mass of TPHG Removed Vs Time • Appendix A Field Procedures • Appendix B Laboratory Analysis Reports for Groundwater Samples and Chain-of-Custody Records • Appendix C Operation and Maintenance Field Data Sheets • Appendix D Laboratory Analysis Reports for Air Samples and Chain-of-Custody Records • Appendix E Groundwater Monitoring Field Data Streets cc Elizabeth Thayer, California Regional Water Quality Control Board Kai Chen, San Joaquin Valley Unified Air Pollution Control Board SACIN\PJM805\08051461 0ES-981Qzusrner2