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A t ,
<br /> Second Quarter Groundwater Monitoring Report June 2003
<br /> Boyett Petroleum,419 S.Main,Manteca,CA
<br /> Page 3
<br /> . Table 2 Groundwater Elevation Data(June 25, 2003)
<br /> Monitor Well TOC Elevation' Screened Depth to Groundwater
<br /> Interval b s Groundwater Elevation
<br /> MW-1 36.16 .13-33 20.82 15.34
<br /> MW-2 35.97 15-25 20.55 15.42
<br /> MW-3 36.18 15-25 20.27 1591
<br /> MW-4 35.38 9-24 NM NM
<br /> MW-5 35.93 10-30 NM NM
<br /> MW-6 36.07 10-25 21.32 14.75
<br /> MW-7 36.42 10-25 20.59 15.83
<br /> MW-8 36.43 10-25 20.73 15.70
<br /> MW-9 35.95 40-50 21.28 14.67
<br /> 'TOC Elevation:Elevations are referenced to NAD83 datum,NGS Benchmark HS 4486.
<br /> 2Groundwater Elevation:Elevations are measured from the top of the well casings and are referenced to the benchmark indicated above.
<br /> Ail measurements are in feet.
<br /> NM=Not measured
<br /> The groundwater elevation contours (Figure 3, attached) estimated using depth to water measurements
<br /> from monitor wells MW-1, MW-2, MW-3, MW-6, MW-7, and MW-8 and well survey data collected by
<br /> Condor indicate a relatively steep groundwater gradient to the southwest. An estimated groundwater
<br /> gradient of 0.0085 ft/ft towards the southwest was calculated using water level data from monitor wells
<br /> MW-2, MW-6, and MW-8. The current southwest gradient is consistent with that reported in the First
<br /> Quarter Monitoring Report March 2003 dated April 3,2003.
<br /> Historic groundwater gradients reported for the site have been highly variable (Table 3, below). Review
<br /> by Condor of historical groundwater gradient information indicates that the historical groundwater
<br /> . gradient is predominantly in a westerly direction at the site. The highly variable gradient at the site may
<br /> be related to off-site domestic/supply well'pumping.
<br /> Table 3 Historic Groundwater Gradients
<br /> Date Approximate Flow Direction Monitor Wells Utilized for Groundwater
<br /> and Groundwater Gradient Gradient Calculations
<br /> September 1, 1999 0.002 ft./ft.-Northwest
<br /> December 10, 1999 0.0010 ft./ft.-Northwest MW-1,MW-2,MW-3
<br /> March 27,2000 0.0 16 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.-West/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.-West/Northwest MW-2,MW-6,MW-8
<br /> September 10,2001* 0,0072 ft./ft.-Northwest MW-2,MW-6,MW-8
<br /> Se tember 26,20021,' 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.-West/Southwest MW-2,MW-6,MW-8
<br /> June 25,2003 0.0085 ft./ft.-Southwest MW-2,MW-6,MW-8
<br /> `— Date inferred
<br /> 2 Condor began conducting quarterly groundwater monitoring at the site
<br /> '— Well collars surveyed;elevations are referenced to NAD83 datum NGS Benchmark HS 4486
<br /> '- Condor recalculated gradient
<br /> i
<br /> i CONDOR
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