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'-41w- TA N i M, HcAL111 FOOTHILL ENGINEERING CREEK LANE LC1. 97 FEB 28 PM 1: 48 12pH. 20p)Dsbs-9-%St FAX C2M p367-1163 CA 95240 Mr. Ronald Rowe February 26, 1997 San Joaquin County Public Health Services Environmental Health Division P. O. Box 389 Stockton, CA 95201 Site Code-91038 Subject: Michael D. & Sharon Olivarez, 300 S. California St. Stockton, Ca. Monitoring Well Information and Results of Sample Analytical Testing Dear Mr. Rowe, On 1124197, Del Tech Geotechnical Support Services under the direction of Foothill Engineering, secured water samples from the monitoring wells on the above stated property. All monitoring wells were in good condition and samples were taken using the standard recommended procedures. Please note: During the sampling of the monitoring on this site, the operator used well identifications different than the numbering that was originally assigned to each well. The author has correct the numbering back to the original method (see the Chain of Custody map attached). FINDINGS MW-1 showed no evidence of a free product on the groundwater surface but had a light sheen. MW- 1 and MW-2 groundwater samples produced lower levels of TPHg than previous samples. MW-3 showed higher levels of TPHg than previous samples (see summary of sample analysis attached). All monitoring wells showed higher groundwater elevations than previously recorded. The groundwater hydraulic gradient was lower than previously recorded ( S=.02 vs. S=.007), with the slope in the south direction. This is a near 90 degree change from the last sample with groundwater elevations nearly two feet higher. CONCLUSIONS The groundwater elevation in all of the wells is much higher, which may account for the lower levels of TPHg. The change hydraulic gradient would account for the higher levels of TPHg in MW-3. Very high precipitation this year may be responsible for the higher groundwater elevations and the change in flow direction. RECOMMENDATIONS Due to the inconsistent results from the enclosed samples, it is recommended that further definition of the contaminated area wait until the results are consistent. Please review the enclosed data, and if you have any questions contact this office. Respectfully submitted, Qe,4FE4 8/{1,t,`' Foot ngl g � a� ;�-`. r 4 97r 9-L in Ri n , P cc: OlivarezT;