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Third Quarter 2003 Groundwater Monitoring Report Eckert Cold Storage,Manteca,California October 14,2003 Page 2 FIELD OBSERVATIONS No separate phase petroleum was noted in the wells, but a slight petroleum odor was noted in groundwater recovered from MW-8. On September 2, 2003 a Condor representative collected depth to water measurements at the site. A measurement could not be collected at MW-7, however, because plant roots were penetrating the well screened interval at approximately 20 feet below ground surface (bgs), thereby obstructing the water level probe from reaching groundwater. A Condor representative removed the root mass in MW-7 with a small-diameter auger on September 3, 2003. Field observation sheets are included in Attachment B. GROUNDWATER ELEVATIONS The average groundwater elevation was approximately 2.37 feet lower on September 2, 2003, than the previous sampling event conducted on June 5, 2003. The groundwater elevation contours (Figure 3, Attachment A) estimated from the depth to water measurements indicate the groundwater gradient was generally towards the northwest on September 2, 2003. Historical groundwater data collected by WHF, Inc. (previous consultant) indicates a highly variable gradient at the site. Review by Condor of historical groundwater gradient information provided by WHF indicates that the general historical groundwater gradient is predominantly towards the northwest at the site. The highly variable gradient at the site may be related to domestic/supply well pumping both on site and off site. At times in the past, the water table slope has been very flat (very gentle groundwater gradient). When this occurs, any slight variability in groundwater measurements and the tolerance for error for the water level measurement devices can result in apparent groundwater elevation contours that are not particularly coherent. Therefore, when the water table at the site is relatively flat, it may be more representative to depict the groundwater gradient with a three-point construction using groundwater elevation data from three site monitor wells. Consistent with this, Figure 4, Attachment A, shows the groundwater gradient direction and magnitude using monitor wells MW-4, MW-5, and MW-6. On September 2, 2003, the groundwater gradient was 0.0020 ft./ft. towards the northwest, as shown. Groundwater elevation data for September 2, 2003 are presented in Table 1, below. Table 1 --Groundwater Elevation Data (September 2, 2003) Monitoring Screened Interval(bgs) TOC Elevation Depth To Water Groundwater Well Elevation MW-1 13 -28 38.09 20.42 17.67 MW-2 15 -30 37.90 20.22 17.68 MW-3 15 -30 38.31 20.65 17.66 MW-4 12-27 37.84 20.46 17.38 MW-5 14-34 41.22 23.72 17.50 MW-6 13 -33 37.65 19.96 17.69 MW-7 13 -33 38.22 NM (Obstruction) NM MW-8 17-37 37.76 20.27 17.49 `TOC Elevation: Elevations are measured from the top of the well casing and are referenced to NGS Benchmark HS4486,elevation 35.03 feet using NAVD 88 datum. NM=Not Measured All measurements are in feet. A Z01� CONDOR