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s <br /> Mr.Harlin Knoll December 8,2000 <br /> San Joaquin County Public Health Services Project No. 2007-0065-01 <br /> Environmental Health Division <br /> Page 3 <br /> The direction of groundwater flow was calculated to be towards the south with an <br /> average gradient of 0.004. Groundwater flow direction and gradient are consistent with <br /> previous monitoring events. <br /> SAMPLING, ANALYSIS, AND MONITORING PROGRAM RESULTS <br /> Groundwater samples were collected from 11 monitoring wells on September 22, 2000 <br /> and forwarded to Alpha Analytical, Inc. for analysis. Samples were analyzed for total <br /> petroleum hydrocarbons as gasoline (TPHG) using United States Environmental <br /> Protection Agency (USEPA) Method 8015B/DHS LUFT Manual and for benzene, <br /> toluene, ethylbenzene, and total xylenes (BTEX compounds) and five oxygenates (methyl <br /> tertiary butyl ether [MTBE], tertiary butyl alcohol [TBA], diisopropyl ether [DIPE], <br /> tertiary amyl methyl ether [TAME], and ethyl tertiary butyl ether [ETBE]) using USEPA <br /> Method 8260B. Certified Analytical Reports with chain-of-custody documentation are <br /> included in Appendix C. <br /> A summary of the groundwater analytical data is presented in Table 2. Petroleum <br /> hydrocarbons and fuel oxygenates were not detected in the samples collected from <br /> monitoring wells MW-1, MW-2, MW-6, MW-7, MW-9, and MW-10. TPHG, BTEX <br /> compounds, and MTBE were detected in the samples collected from monitoring wells <br /> MW-3, MW-8, S-1, and S-2. TPHG was detected in the sample collected from <br /> monitoring well MW-4 at a concentration of 0.052 mg/L. TBA was detected in the <br /> samples collected from monitoring wells MW-8, S-1, and S-2 at concentrations of 330, <br /> 5,500 and 340 µg/l, respectively. TAME was detected in the samples collected from <br /> monitoring wells MW-8, S-1, and S-2 at concentrations of 25, 22, and 45 µg/1, <br /> respectively. <br /> SOIL VAPOR EXTRACTION SYSTEM <br /> Stratus oversaw the construction and installation of a SVES in July and August 2000 <br /> under an authority to construct issued by the SJVUAPCD. The SVES consists of a 150 <br /> cubic feet per minute catalytic oxidizer with a 5 horsepower blower. Soil vapors are <br /> extracted from the subsurface by the blower and abated in a catalytic oxidizer before <br /> discharge to the atmosphere. <br /> A system startup and source test was conducted on August 15, 2000. The SVES has <br /> operated continuously since startup, with the exception of two intentional shutdowns. <br /> System shutdowns were to accommodate paving and the third quarter 2000 groundwater <br /> monitoring event. Tables 3, 4, and 5 show the operating time, air sample analytical <br /> results, and the destruction efficiency of the SVES, respectively. Field data sheets are <br /> C:Troject FileslUSA Gasoline10651Qtr1y13Q00.doc SrRAWS <br />