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k., FQuarterlyGround-Waterd-Water Monitoring January 8, 1990 o. 502, Lodi, CaliforniaAGS $6041-7 by Environmental Protection Agency Method 602. The results of these vious laboratory analyses are summarized in Table 2. Copies of the . aoratory Analysis Reports are attached. The results of the laboratory analyses indicate that hydrocarbon constituen_; were not detected in the s-round-water samples collected from MW-2. MW-3, and MW-5 but were detected in the samples from MW-1 and MW-4. TPH as gasoline was detected at 0.210 parts per million (ppm) in the sample from MW-4 and at 0.150 ppm in the sample from MW-1. Concentrations of the BTEX compounds decreased since the July 21, 1989, sampling,with the exception of an increa,e in benzene detected in the sample from MW-4. Applied GeoSystems evaluated the groundwater gradient across the site on November 21, 1989. The elevation of the top of the casing to each well was evaluated by Moldenhauer Engineering Company,a licensed land surveyor of Davis,California on November 2'x,1989. Elevations were measured in feet relative to mean sea level ur,ing a local U.S. Geological Survey benchmark as a datum. The measurements of the depths to ground water were combined with the casing elevations to calculate the elevations of the ground-water surface. These data are summarized in Table 3 and were used to evaluate the gradient of the W groundwater surface at the time of this quarterly monitoring event (Plate P-3). The average ground-grater gradient was evaluated to be 0.005,with a flow direction towards the southwest; the magnitude of the gradient appears to be greater on the northeast end of the site. The orientation of the ground-water gradient is similar to that evaluated in previous sampling events. �+ Applied GeoSystems recommends that monitoring of ground water at the site be continued on-%-'quarterly basis. The next sampling event has been scheduled for the week of December 18. 1989. 2 L AppIleal GeoSystems