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16 S0TXj _ <br /> Environmental Technology Inc <br /> The eight water samples collected were stored in an ice chest maintained at 4"� <br /> degrees Celsius Appropriate chain of custody was prepared prior to <br /> transporting to a State certified laboratory Columbia Analytical Services <br />' Canoga Park, CA performed the laboratory analyses All the water samples <br /> were analyzed for Total Petroleum Hydrocarbons (TPH) as gasoline (Volatile Fuel <br /> Hydrocarbons), Benzene Toluene, Ethylbenzene, and Xylenes (BTEX) following <br /> EPA Methods 8015020 and, as requested by Mr Michael Infarna, Senior <br /> t REHS Site Mitigation Unit San Joaquin County, SOTA also analyzed for MTBE ./ <br /> (Methyl-tert-Butyl Ether) The test data are presented in Table 2 <br /> All laboratory analytical results including QA/QC are enclosed with this letter <br /> report Table 2 also includes the historical data for wells MW-1 through MW-8 <br /> The groundwater level observations (Table 1) indicated a decrease of <br /> approximately 0 77 to 0 24 feet for MW-1 to MW-6 during the reporting period <br /> (02/08/96 and 06/26/96) However MW-7 and MW-8 showed a groundwater <br />' level increase of 0 62 and 0 OG feet respectively It should be noted that the <br /> fluctuation in groundwater level is a common orcurrence in the Stockton area <br /> as reporters by Applied Consultanis Dita April 9, 1994 Figure 2 presents the <br /> groundwater contour map It appears that the general groundwater flow <br />' direction is toward the Southwest dui ing the reporting pei iod <br /> During the reporting period 02/08/96 through 06/26/96, TFH (gasoline) <br /> concentration in MI V-I has reduced from 60 µg/l (ppb) to ND (<50 ppb) MW-3, <br /> MW-5 and MW-8 have remained at ND (<50 ppb) However, NAV-2, 1Lf1YY-4 MW- <br /> 6 and MW-7 have incre� _armed from ND, 4,800, ND and 130 to 150, 11,000, 520 <br /> and 7600 pp respectively A TPH concentration contour xnap is preserited iii <br />' Figure 3 <br /> During; the reporting period 02/08/96 thi ough 06/26/96, Benzene <br />' concentrations in MW-2, MW-4, MW-6, MW-7, and MW-8 have zrease rom <br /> 1 0, 670. 2 3, 1 4, and ND (<O 30 ppb) to 76, 1,600, 180, 69, and 4 9 <br /> respectively However benrerie corceiiti atlon in MW-1 MW-3 and MW-5 <br /> showed a consistent decrease MW 1 decreased from 2 0 to 1 6 ppl) MPJ-3 <br />' decreased from 2 8 to ND (<0 5 ppb) and MIN-5 decreased from. 0 75 to ND (<O 5 <br /> ppb) A Benzene/concentration contour map is presented in Figure 4 <br />' Based on there and past observations, SOTA proposes 11iither gnarterly <br /> groundwater monitoring to evaluate the seasonal change in the groundwater <br /> contamination plume at this location <br />' Wastes generated dui irg the di zll.ng (October 1995) and periodic groundwater <br /> sampling operations at U-Haul, Stockton were temporarily stored in 55 gallon <br /> DOT approved drums at the U-Haul facility On July 31, 1996, Belshire <br />' Environmental Services Inc , following approval from SOTA Environmental <br /> Technolrgy Inc transported 17 drums of soil and 30 drums ref water to TPS and <br /> DeMenno Kerdc n respectively for treatment and eventual disposal Copes of <br /> the manifests'nand non-hazardous waste data form (water) are included in <br /> Appendix A <br /> 2 <br />