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C ►Vs 6 I Ms. Margaret Lagorio <br /> August 15, 2001 <br /> MASS REMOVAL BY GROUNDWATER EXTRACTION <br /> Constituent Total Removed <br /> Total Hydrocarbons 1.7 lbs <br /> MTBE 15.2 lbs <br /> Water 2,173,500 gals <br /> Initially, the GWE system was operated on a batch basis, in which a limited volume of water was <br /> extracted, stored aboveground, and then hauled offsite for disposal. Continuous discharge to the <br /> sanitary sewer was started on May 19, 2000. <br /> The system operated continuously during the second quarter of 2001, except for the period from <br /> May 22, 2001 to May 27, 2001 during a soil-vapor extraction (SVE) feasibility test and repair and <br /> replacement of the GWE pump. <br /> Carbon Changeouts: Cambria performed a carbon changeout on June 19, 2000 and restarted the <br /> system on June 20, 2000 after the carbon had been soaked overnight. Cambria shut the system <br /> down on July 12, 2000 when methyl tert butyl ether (MTBE) was detected in the GWE-system <br /> effluent. The carbon filter media in two of the three filter vessels was removed and replaced, and <br /> the PVC hoses between the carbons were replaced. The GWE system was restarted on a batch <br /> basis, resampled, and shut down on July 18, 2000 and August 10, 2000 pending approval from <br /> the City of Ripon to operate on a continuous basis. The GWE system was restarted on a <br /> continuous basis on September 19, 2000. <br /> Sampling and Analytical Frequency: Cambria monitored and sampled the remediation system <br /> on a bi-weekly basis during the quarter. The system effluent was sampled on a bi-weekly basis, <br /> and the other remediation system samples were collected on a monthly basis. The samples were <br /> analyzed for total petroleum hydrocarbons as gasoline, benzene, toluene, ethylbenzene, xylenes <br /> and MTBE by EPA Method 8020 and MTBE by EPA Method 8260. Analytical results for the <br /> GWE system are summarized in Table 2. <br /> SVE Feasibility Testing: Cambria performed an SVE feasibility test on wells EW-1, MW-1 and <br /> MW-413 on May 22, 2001. The purpose of the test was to determine if there are any <br /> hydrocarcarbons in the unsaturated zone below 22 feet below ground surface and above the <br /> groundwater table. The results of the test were included in Cambria's Soil Vapor Extraction <br /> Feasibility Test Report, dated June 22, 2001. <br /> • <br /> 2 <br />