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<br /> First Quarter Groundwater Monitoring Report March 2003
<br /> Boyett Petroleum,419 S.Main,Manteca,CA
<br /> Page 3
<br /> Table 2 Groundwater Elevation Data arch 21, 2003)
<br /> Monitoring Well TOC Elevation Screened Depth to Groundwater
<br /> Interval(b s) Groundwater ElevationZ
<br /> MW-1 36.16 13-33 18.08 18.08
<br /> MW-2 35.97 15-25 17.83 18.14
<br /> MW-3 36.18 15-25 18,03 18.15
<br /> MW-4 35.38 9-24 17.25 18.13
<br /> MW-5 35.93 10-30 DRY NM
<br /> MW-6 36.07 10-25 18.02 18.05
<br /> MW-7 36.42 10-25 18.33 18.09
<br /> MW-8 36.43 10-25 18.34 18.09
<br /> MW-91 35.95 40-50 17.91 18.04
<br /> `TOC Elevation: Elevations are referenced to NAD83 datum by post-processing the base station against the Condor Stockton(CNDR) CORS
<br /> Station NGS Benchmark HS 4486,elevation 35.03 feet.
<br /> 20roundwater Elevation:Elevations are measured from the top of the well casings and are referenced to the benchmark indicated above.
<br /> All measurements are in feet
<br /> NM=Not measured
<br /> The groundwater elevation contours (Figure 3, attached) estimated using depth to water measurements
<br /> from monitoring wells MW-1, MW-2, MW-3, MW-6, MW-7, and MW-8 and well survey data collected
<br /> by Condor indicate a relatively gentle groundwater gradient to the west/southwest. An estimated
<br /> groundwater gradient of 0.0008 ft/ft towards the west/southwest was calculated using water level data
<br /> from monitor wells MW-2, MW-6, and MW-8. The current west/southwest gradient represents a reversal
<br /> from that reported in the Fourth Quarter Monitoring Report December 2002, dated February 12, 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. -Nortliwest
<br /> December 10, 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. -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 /> September 26,20022.3 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 /> '— Date inferred
<br /> 2— Condor began conducting quarterly groundwater monitoring at the site
<br /> 3— Well collars surveyed,elevations are referenced to NAD83 datum by post-processing the base station against the Condor Stockton(CNDR)
<br /> CORS Station NGS Benchmark HS 4486,elevation 35.03
<br /> - Condor recalculated gradient
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<br /> �� CONDOR
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