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v Third Quarter 2004 Groundwater Monitoring Report
<br /> Boyett Petroleum,419 S.Main,Manteca,CA
<br /> Page 3
<br /> . Table 2: Historical Groundwater Gradients
<br /> Date Approximate Flow Direction Monitoring Wells Utilized for Groundwater
<br /> and Groundwater Gradient Gradient Calculations
<br /> September 1, 1999 0.002 ft./ft.-Northwest
<br /> December t0, 1999 0.0010 ft./ft. -Northwest MW-1,MW-2,MW-3
<br /> March 27,2000 0.016 ft./ft. -Northeast MW-1,MW-2,MW-3
<br /> June 23,2000 0.0021 ft./ft. -Southeast MW-1,MW-2,MW-3
<br /> September 8,2000 0.004 ft./ft.-Southeast MW-1,MW-2,MW-3
<br /> December 2000"- 0.0021 ft./ft.-Southwest MW-2,MW-6,MW-8
<br /> March 5,2001* 0.0061 ft./ft.-Northeast MW-2,MW-6,MW-8
<br /> June 4, 2001* 0.005 ft./ft.-Northwest MW-2, MW-6,MW-8
<br /> September 10,2001* 0.0072 ft./ft. -Northwest MW-2,MW-6,MW-8
<br /> September 26,2002 ' 0,0058 ft./ft-Southwest MW-2,MW-6,MW-8
<br /> December 27,2002 0,0036 ft./ft.-Northeast MW-2,MW-6, MW-8
<br /> March 21,2003 0.0008 ft./ft.-South MW-2,MW-6,MW-8
<br /> June 25,2003 0.0085 ft./ft. -Southwest MW-2, MW-6,MW-8
<br /> July 22, 2003 0.0094 ft./ft. -Southwest MW-2, MW-6,MW-8
<br /> August 19,2003 0.0089 ft./ft. -Southwest MW-2, MW-6,MW-8
<br /> September 30, 2003 Not Calculated MW-2 dry; MW-6 and MW-8 purged dr
<br /> October 31,2003 Not Calculated Lack of Data
<br /> November 26,2003 0.0315 ft./ft. -Southwest MW-3, MW-4R,MW-10
<br /> December 31,2003 0.0057 ft./ft. -North MW-2,MW-6,MW-8
<br /> March 4,2004 0.0048 ft./ft. -Northeast MW-2,MW-6,MW-8
<br /> June 24,2004 0.0217 ft./ft.- South MW-2,MW-6,MW-8
<br /> September 28, 2004 Not Calculated MW-2 and MW-6 were dry
<br /> 1- Date inferred
<br /> .
<br /> 2- Condor began conducting quarterly groundwater monitonng at the Site
<br /> 1 Well collars surveyed;elevations are referenced to NAVD98 datum NGS Benchmark HS 4486
<br /> * Condor recalculated gradient
<br /> LABORATORY ANALYTICAL RESULTS
<br /> The groundwater samples collected from the monitoring wells were analyzed for benzene, toluene, ethyl
<br /> benzene, total xylenes (BTEX), and selected gasoline oxygenates/additives by EPA Method 826013, and
<br /> for total petroleum hydrocarbons quantified as gasoline (TPH-G) by EPA Method 8015B by Argon
<br /> Laboratories of Ceres, California. The selected oxygenatesladditives included MTBE, ethanol (EtOH),
<br /> tertiary-butanol (TBA), di-isopropyl ether (DIPE), ethyl tertiary-butyl ether(ETBE), tertiary-amyl methyl
<br /> ether(TAME), 1,2-dichloroethane (1,2-DCA), and 1,2-dibromoethane(EDB).
<br /> The laboratory analytical results for the third quarter 2004 quarterly groundwater monitoring event are
<br /> presented in Table 3, on the next page. A map presenting MTBE concentrations in groundwater is
<br /> included as Figure 5, attached.
<br /> 41s
<br /> �r� CONDOR
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