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17 July 2000 <br /> AGE-NC Project No 98-0511 <br /> Page 3 of 4 <br /> 32 ANALYTICAL RESULTS OF WATER SAMPLES <br /> TPH-g and BTEX compounds were detected in the ground water samples collected from MW-1 at <br /> concentrations of 3,500 parts per billion (ppb, reported as micrograms per liter), 180 ppb, 210 ppb, <br /> 110 ppb and 590 ppb, respectively <br /> MTBE was detected by EPA Method 8020 in the ground water sample collected from MW-3 at a <br /> concentration of 10 ppb MTBE was detected by EPA Method 8260 in the ground water samples <br /> collected from MW-3 at a concentrations of 8 1 ppb No other fuel oxygenated compounds were <br /> detected above laboratory reporting limits <br /> Analytical results of ground water samples are summarized on Table 2 The laboratory report (MAI <br /> Laboratory ID 40186-40189) and chain-of-custody forms are included in Appendix B <br /> 33 RECEPTOR SURVEY <br /> Two municipal wells were Identified within the 2,000-foot search radius Lathrop City Well #1 is <br /> located approximately 300 feet south of the site The second municipal well, Lathrop County Water <br /> Well is located approximately 600 feet southwest No domestic wells were Identified during the field <br /> reconnaissance in the 2,000-foot radius, but a search of Department of Water Resource Records <br /> indicated three possible Iocations The nearest domestic well down-gradient from the site is <br /> approximately 1,000 feet southwest (Lathrop Grammar School) Three monitoring wells are located <br /> approximately 300 to 1,000 feet east of the site A map depicting well locations is presented in <br /> Figure 4 A summary of well Information is included on Table 3 Drillers reports are presented in <br /> Appendix C <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> Based upon data collected from the site, AGE concludes the following <br /> • The ground water gradient was calculated to be 0 001 ft/ft directed S 89° W <br /> • TPH-g and BTEX compounds were detected in MW-1 <br /> • Petroleum hydrocarbons were not detected in MW-2 through MW-4 <br /> • MTBE was detected at concentrations as high as 10 ppb in monitoring well MW-3, <br /> exceeding the State of California's secondary MCL of 5 ppb, but not exceeding the State of <br /> 46 California's action level of 13 ppb <br /> Advanced GeoEnvironmental,Inc <br />