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FOOTS IILL .1 2793 PADDY CREEK LANE L LL<DD CA 9-9240 • hr111: 47 _ PH, (209) 36$-9381 FAX (209) 367-1163 Ms. Carol Oz October 25, 1999 San Joaquin County Public Health Services Environmental Health Division P. O. Box 388 Stockton, CA 95201 Site Code 9 038 Subject: Michael D. & Sharon Olivarez, 300 S. California St. Stockton, Ca. Monitoring Well Information and Results of Sample Analytical Testing of 7/19'90) Dear Ms. Oz: On 7119199, Del Tech Geotechnical Support Services secured water samples. from the monitoring wells on the above stated property. The work was supervised by Foothill Engineering. :ill monitoring wells were in good condition and samples were taken using the standard recomnlen:led procedures. All samples were extracted using the tube with check valve pump system. Pui-_Lc: volumes and the physical properties of the ground water are attached in the Del-Tech held log All samples were transported under chain of custody to Sherwood Labs of Hilmar, Cal ifornin for analysis by EPA methods 602 and 5030/8015 . Samples from each monitoring well were tra:-v po rte-d . from Sherwood Labs to Entech Analytical Labs, Inc. for oxygenate analysis, EPA method 8260V under chain of custody.All water sample analysis and groundwater elevations are summarized, in;IN,attached tabular form with original data also attached. FINDINGS The groundwater elevation in all of the wells has risen +/- 1.5' from the last samplil-!2 dL11 V (12/29/98). The direction of groundwater flow is to the Northeast (see attached map). r,41h'-1 and MW-2 were analyzed to have highest concentration of gasoline contamination at 71700 pph. ti9 and MW-3 produced groundwater samples with lower levels of TPHg than previous sample,; from the same well. MW-2 produced samples of higher concentrations of TPHg. All monitoring wells showed higher groundwater elevations than previously recon-Jed. `rhe groundwater hydraulic gradient was calculated at S=0.004 with the slope in the Northeasl dir:ctlOtl. New monitoring wells MW-IR, MW-2R, and MW-3R were sampled and analyzed as replaoir'enl wells for MW-1,MW-2,and MW-3 that have water elevations that produce over screen con.11i.:».s. The sampling of all monitoring wells on the site was done for comparison. CONCLUSIONS The groundwater elevation in all of the wells is approximately 1.5 feet higher than last sampled. The raise in groundwater in the calender year of 1999 is typical of all areas in the City of Snocklon. Up gradient monitoring well MW-3 has produced samples with lower concentrations of Ti,i-i c than 1