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First Quarter,2002 Quarterly Groundwater Monitoring Report Eckert Cold Storage,Manteca,California Page 2 Nature of contamination: BTEX, Range in concentrations: TPH-G, Benzene(µg/L) <0.5—440 TPH-D TPH-G(mg/L) <0.05—8.2 Oxygenates TPH-D(mg/L) <0.05— I.1 /Additives MTBE(gg/L) <0.5—23 Tertiarty butanol(Etg/L) <5.0— 190 1,2-DCA(µg/L) <0.5— 15 FIELD OBSERVATIONS No sheen or separate phase petroleum was noted in the wells, but a strong petroleum odor was noted in MW-1 and moderate petroleum odors were noted in well MW-3 and MW-8. Field observation sheets are included in Attachment B. GROUNDWATER ELEVATIONS The average groundwater elevation was approximately 1.4 feet higher on February 27, 2002 than the previous sampling event conducted on December 17, 2001. The groundwater elevation contours (Figure 3, Attachment A) estimated with the depth to water measurements and the new survey data collected by Condor indicate that the groundwater gradient was generally towards the northwest on February 27, 2002. It should be noted that the groundwater table was above the top of the well screen in MW-8. On April 8, 2002, Condor representatives re-surveyed the monitoring wells at the site using traditional and global positioning system (GPS) techniques in accordance with recent CRWQCB directives concerning UST site data to be submitted in Electronic Deliverable Format (EDF). The new survey data indicates potential discrepancies between the prior elevation data and the current elevation data, • particularly associated with MW-5. The top of casing elevations measured for MW-1, MW-2, MW-3, MW-6, MW-7, and MW-8 identified during the new survey were either 2.28 or 2.29 feet higher than measured by the prior survey conducted by WHF, Inc. (WHF). This indicates that there is good agreement between the data from both surveys for the relative elevations of those monitor wells. The top of casing elevations measured during the new well survey for MW-4 and MW-5, however, were 2.34 and 2.52 feet higher, respectively, than the top of casing elevations measured during the prior WHF survey. For MW-5 in particular, therefore, it is possible that the previous top of casing elevation was measured to be approximately 0.23 feet too low relative to the other site monitor well top of casing elevations. This may have occurred during the re-survey of the well on April 25, 2000 following repairs to the well as reported by WHF in previous quarterly monitoring reports. Historical groundwater data collected by WHF indicates a highly variable gradient at the site. Review by Condor of historical groundwater gradient information provided by WHF indicates that there are potential inconsistencies in the data and possibly components of the interpretation of those data, especially related to MW-5 measurements. However, Condor agrees 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 fiat, it may be more representative to depict the groundwater gradient with a three-point construction using groundwater elevation data from three site monitor wells that circumscribe th.- site, allowing triangulation of the contaminant plume, including the contaminant source area. Consistent with this, Figure 4, Attachment A is provided showing the groundwater gradient direction and magnitude using monitor wells MW-3, MW-4, and MW-6. On February 27, 2002 the groundwater gradient was 0.0042 CONDOR