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w. ��d9.. wrf':�erzmrieae =aPttr�nertaw. Subsurfece investigation aesetts 6131 pacific Ave., Stockton, CA. Aegis project No. 90.020 Page 9 2.8 SITE HYDROGEOLOGICI__REOIONAL GEOLOGY A complete review of the is included in Aegis' Pre-Tank Replacement Site Assessment Work Plan (Aegis March 6, 1990) . 2.9 WATER WELL INFORMATION A water well search will be conducted through the state of California Department of Water Resources to located water wells within 1/2 mile radius of the Site. 3.0 RESULTS OF SUBSURFACE INVESTIGATION A total of fourteen soil borings were advanced at the locations 's shown on Figure 5. Soil borings B-9 through B-14 were advanced to 21.0 feet below grade. Soil borings B--2 through B-S were advanced _ to 46.0. feet below grade, soil boring B-1 was drilled to 55 feet below grade. Lags of the soil borings are included in Appendix B. h A total of 28 soil samples from 'Che borings were submitted to a state-certified-laboratory for analyses. Copies of laboratory j reports are included in Appendix C. 3.1 SOIL CONDITIONS i Fourteen soil borings were drilled, sampled and logged, according to the methods described in Appendix A (B-1 was not sampled) . The soil borings ranged from 21.0 ft. to 55 ft. below grade. Soil Boring B-1 was advanced to ground water, away from suspected soil contamination. The soil boring logs were used to compile generalized cross section A-A, ' which is presented in Figure 6. As depicted in the cross section, silts varying from c3,ayey.to sandy composition were the predominant soil type encountered (Unified soil Classification System symbol ML) . Generally silty clays occurred at shallow depths, followed by interlayered horizons of sandy silts. Most of the deeper borings ended in clayey silts. Soil types ranged from a fine grained silty clays to medium grained silty sand, to sand. As shown on the cross section, soil types beneath the site generally coarsen with depth.