ARCHIVED REPORTS_QUARTERLY GROUNDWATER MONITORING REPORT 1ST QUARTER 2016

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Quarterly Groundwater Monitoring Report - First Quarter 2016 L&M Operable Unit- West Weber Avenue and North Lincoln Street,Stockton, CA April 29, 2016 • 3.1.4 Historic DPE Mass Removal (Vapor) Between March 18, 2004 and March 27, 2014 the vapor extraction portion of the system removed approximately 17,972.7 lbs (2,964.3 gallons) of TPHg; 8.08 lbs (1.12 gallons) of TPHd; 13.4. lbs (1.8 gallons) of benzene; and 3.75 (0.61 gallons) of MTBE from the subsurface. Historic operating and analytical data can be found in Appendix D. 3.2 L&M OU AND APARTMENT SOIL VAPOR EXTRACTION SYSTEMS The on-site SVE remedial system was comprised of two units, one SVE unit to remediate under the former excavation footprint on the L&M OU property and a second unit to remediate beneath the Delta View Apartments. Both the L&M OU SVE and the Delta View Apartment ASVE on-Site SVE systems have been shut down since October 16, 2013. Historic operating and analytical data can be found in Appendix D. 3.3 OFF-SITE PRODUCT RECOVERY REMEDIATION SYSTEM SUMMARY A skimmer based product recovery remediation system was installed off-site in the Waterfront Towers (WFT) parking lot to recover SPH associated with the Site. The active product recovery system consists of an extraction point (MW-50) and a 247 gallon double walled product holding • tank with manual drain, level indicator, and leak detection alarm on a 7 ft. x 7 ft, skid. The holding tank is additionally coupled to two 55-gallon carbon drums connected in series. The product holding tank is supplied by a 5 hp Powerex model SES0508HP 4-2 rotary scroll air compressor and a 13 gallon receiving tank. The compressor is tied to a 2-inch SPG2 AutoGenie m skimmer bladder pump installed in MW-50 and capable of removing up to 160 gallons of SPH per day. Compressed air is supplied to the pump via independent piping and regulated by a QED Environmental Systems pressure regulator mounted inside the remediation enclosure. In addition to the active skimmer in MW-50, four passive skimmers are associated with the system. The passive skimmers are installed in wells 2AMW-14, MW-43, MW-48, and MW-49. A Notice of Permit Exemption was obtained from the SJVAPCD on January 16, 2013. The product recovery system was started on September 11, 2013. A system startup report detailing the startup, operation and maintenance, and recovery status of the free product removal system was submitted on February 13, 2014. 3.3.1 Product Recovery Remedtatlon System Operational Data The active skimmer system was found down on arrival on February 24, 2016. Upon inspection the supply line on the air compressor was found to be leaking as a result of a broken filter. The system was left off pending replacement of the filter. On March 17, 2016 the filter was replaced and the system restarted. The system operated without incident for the remainder of the • quarter. 5 Stantec 10