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Mr. Harlan Knoll February 2, 2001 <br /> Page 4 Project No.2007-0065-01 <br /> The system is unable to extract high flows from the subsurface even at high applied <br /> vacuums. The influent concentrations of the petroleum hydrocarbons continues to drop, <br /> as is typical in SVE systems, but mass extraction rates are low due to low flow rates. <br /> Attempts to increase flow rates by increasing vacuum are unsuccessful because the <br /> increased vacuum raises the water level in the vapor extraction well, submerging the <br /> screen interval. Stratus proposes to install a vapor extraction well screened above the <br /> water table to extract more soil vapors and increase mass extraction rates. <br /> The SVES has extracted a cumulative mass of 408.6 pounds (approximately 66 gallons of <br /> gasoline) quantified as TPHG from the subsurface. The mass extraction rates have <br /> decreased from 14.03 to 2.0 pounds per day, due to the decrease of influent TPHG <br /> concentrations. TPHG concentrations have decreased by approximately eighty-eight <br /> percent (88%) since startup. <br /> The SVES is in compliance with the SJVUAPCD. Stratus will continue to optimize and <br /> maintain the SVES in first quarter 2001. <br /> CONCLUSIONS <br /> • The highest concentrations of TPHG, TBA, and MTBE in groundwater were detected in <br /> the sample collected from monitoring well S-1. The highest concentration of benzene was <br /> detected in the sample collected from monitoring well MW-8. Groundwater flow <br /> direction was toward the south at an average gradient of 0.0035 ft./ft. The SVES has <br /> extracted a cumulative mass of approximately 185.6 pounds of TPHG during the fourth <br /> quarter 2000. <br /> STATEMENT OF LIMITATIONS <br /> The services described in this report were performed consistent with generally accepted <br /> professional consulting principals and practices. No other warranty, expressed or <br /> implied, is made. These services were performed consistent with our agreement with our <br /> client. This report is solely for the use of our client unless otherwise noted. Any reliance <br /> on this report by a third party is at such party's sole risk. <br /> If you have any questions, please contact Gowri Kowtha at (530 676-6001. <br /> Sincerely, <br /> 5rR X60 NMENTAL, lNC. <br /> o� owtha y J son, R.G. <br /> . Project Manager Pri cip Geologist <br /> CAProject ReAUSA Gaso1ine100651Qtr1y14Q00.doc 5rRArU5 <br />