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<br /> Third Quarter Groundwater Monitoring Report September 2003
<br /> Boyett Petroleum,419 S.Main,Manteca,CA
<br /> Page 6
<br /> Table 4: Groundwater Elevation Data (September 30, 2003)
<br /> Monitor Well TOC Elevation Screened Depth to Groundwater
<br /> Interval (b s) Groundwater ElevationZ
<br /> MW-1 36.16 13-33 24.09 12.07
<br /> MW-2 35.97 15-25 DRY NM
<br /> MW-3 36.18 15-25 22.15 14.03
<br /> MW-4 35.38 9-24 DRY NM
<br /> M W-5 35.93 10-30 DRY NM
<br /> MW-6 36.07 10-25 24.33 11.74
<br /> MW-7 36.42 10-25 23.21 13.21
<br /> MW-8 36.43 10-25 23.04 13.39
<br /> MW-9 35.95 40-50 22.46 13.49
<br /> 'TOC Elevation:Elevations arc referenced to NAD83 datum,NGS Benchmark HS 4486.
<br /> 'Groundwater 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 7, attached) estimated using depth to water measurements
<br /> from monitor wells MW-1, MW-3, MW-6, MW-7, and MW-8 and well survey data collected by Condor
<br /> indicate a relatively steep groundwater gradient to the southwest. An estimated groundwater gradient for
<br /> the third quarter 2003 was not calculated due to the low groundwater elevations in monitor wells MW-2,
<br /> MW-6, and MW-8. Water level measurements indicate that groundwater elevations at the site are at the
<br /> lowest recorded levels since monitoring activities were initiated in September 1999.
<br /> Historic groundwater gradients reported for the site have been highly variable (Table 5, below; Figure 8,
<br /> • attached). Review by Condor of historical groundwater gradient information indicates that the historical
<br /> groundwater gradient is predominantly in a westerly direction at the site. The highly variable gradient at
<br /> the site may be related to off-site domestic/supply well pumping.
<br /> Table S: 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 20001•* 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' 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 /> It 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 dry
<br /> `— Date inferred
<br /> '— Condor began conducting quarterly groundwater monitoring at the site
<br /> s— well collars surveyed;elevations are referenced to NAD83 datum NGS Benchmark HS 4486
<br /> *- Condor recalculated gradient
<br /> is CONDOR
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