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r r WATER TABLE ELEVATIONS AND GRADIENT The static water table at the time of the second sampling (l0/19/98) in all monitoring wells has lowered about two feet from the samples taken on 6/11/98 (see SUMMARY OF WATER TABLE ELEVATION) The third set of samples showed an additional groundwater raising of four feet over the recorded elevations of 10/19/98 As a result of the change in water table elevations, the hydraulic gradient of the water table has changed The original direction of flow gradient was South 75 degrees East, and on 10/19/98 it was almost due East The latest down slope direction is North 80 degrees East with S=0 002 Pump rates for purging continue to be between 1 0 gpm and 2 0 gpm WATER SAMPLE ANALYSIS In general, monitoring well samples taken on 4/01/99 tested higher in compound concentrations than did the samples taken on 10/18/98(see BTEX&PURGEABLE HALOCARBONS summary) Analysis by EPA test Method 8260A were made on a]1 monitoring wells and all samples were non- detect CONCLUSIONS BETX compounds in the MW#3.S remain near the same concentrations as the last sampling event This monitoring well is receiving the highest impact of all the wells due to TANK#I( the Stoddard's Solvent tank), which is Northwest of MW#3S All other monitoring wells are below detection limits for BETX Chlorine compounds are present in Iow concentration in all but MW#4S The Halocarbons concentrations in water samples are about the same as the last testing period RECOMMENDATIONS The author recommends that all monitoring wells be sampled in the second quarter of 1999 to expand and reinforce the present monitoring well data Please contact this office at 209/368-9381 if any questions arise from this report Respectfully submitted, Foothill Engtnee t 0 i UP Ervin Ri enbu , RC �r cc Helen Higgins 2