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<br /> Environmental Technology Inc — 400Vw
<br /> The eight water samples collected were stored in an ice chest maintained at 4 degrees
<br /> Celsius Appropriate chain of custody was prepared prior to transporting to a State certified
<br />' laboratory. Columbia Analytical Services Canoga Park, CA performed the laboratory
<br /> analyses All the water samples were analyzed for Total Petroleum Hydrocarbons (TPH) as
<br /> gasoline (Volatile Fuel Hydrocarbons), Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX)
<br />' following EPA Methods 8015/8020 and MTBE (Methyl-tert-Butyl Ether) The test data are
<br /> presented in Table 2
<br /> All laboratory analytical results including QA/QC are enclosed with this letter report
<br />' (Appendix A) Table 2 also includes the historical data for wells MW-1 through MW-8
<br /> The groundwater level observations (Table I) indicated a consistent decrease of approximately
<br />' 8 55 to 8 29 feet for all monitoring wells during the reporting period (06/26/96 and
<br /> 09/26/96). It should be noted that the fluctuation in groundwater level is a common
<br /> occurrence in the Stockton area as reported by Applied Consultants Data, April 9, 1994
<br /> Figure 2 presents the groundwater contour map It appears that the general groundwater
<br />' flow direction is toward the Northeast during the reporting period
<br /> During the reporting period 06/26/96 through 09/26/96, TPH (gasoline) concentrations in
<br />' MW-1, M-3, M-4, M-6 and MW-7 have increased from ND (<50 ppb), ND, 11,000, 520, and
<br /> 760 ppb to 290, 410, 41,000, 18,000 and 6,000 respectively MW-5 and MW-8 have
<br /> remained at ND (<50ppb) However, TPH (gasoline) concentration in MW-2 reduced from 150
<br /> to 78 ppb A TPH-g concentration contour map is presented in Figure 3
<br /> During the reporting period 06/26/96 through 09/26/66, benzene concentrations in MW-1,
<br /> MW-3, MW-4, MW-6 and MW-7 have increased from 1 6, ND (<0 5), 1,600, 180 and 69 ppb to
<br />' 96, 110, 6,400, 4,600 and 310 ppb respectively The benzene concentration in MW-5
<br /> remained consistent at ND (<0 5 ppb) However, during the reporting period, the benzene
<br /> concentrations in MW-2 and MW-8 decreased from 150 and 4 9 to 78 and ND (<0 50) ppb
<br />' respectively A benzene concentration contour map is presented in Figure 4 Additionally
<br /> MTBE (Methyl-tert Butyl-Ether) concentrations remained consistent for MW-1, MW-2, MW-3.
<br /> MW-5, and MW-8 at ND (<10 0 ppb) However, MW 4, MW 6, and MW-7 indicated an
<br /> increase MW-4 increased from 20 to <500 ppb MW-6 increased from ND (i e. <10 0) to
<br /> <200 ppb and MW-7 increased from ND (i a <10 0) to <50 ppb during the reporting period
<br /> (06/26/96 to 09/26/96)
<br /> t Should there be any questions regarding this transmittal please contact me or John
<br /> McAndrew at (619) 485-8100
<br /> Sincerely,
<br /> SOTA Environmental Technology, Inc .
<br /> Dakshana Murthy, Ph D , P E
<br /> Project Manager
<br /> cc Doug Dunham, U-Haul International, Phoenix, AZ
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