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1 <br /> Union Ice Company <br />' 1310 West Weber Avenue, Stockton, Calefornia July 11, 1994 <br /> Phase IVRemei iation Report of Findings Page- 5 <br />' Lithologies sunilar to those discussed above underlie the site to depths of several <br /> hundred feet <br />' SO <br /> Groundwater Conditions <br /> iFirst groundwater was encountered m Sand 1 at depths of 13 to 15 feet This aquifer is <br /> slightly artesian The piezometnc surface is from two to five feet (2 - 5') above the top of <br />' Sand 1 The piezometnc surface in the Sand 2 aquifer is about 16 feet below the piezometnc <br /> surface in the Sand i aquifer <br /> Aquifer properties of the Sand 1 aquifer vary greatly across the site Trarsmissibility vanes <br /> from 158 to 21,534 gpd/foot, and the co-efficient of storage vanes from 4 OxE-4 to <br /> 4 lxE-2 These variables result from thickness and permeability variations in the Sand 1 <br />' aquifer Sand 1 is not a uniform sand, therefore, its aquifer properties are not umfonn <br /> Sampling of the upper aquifer wells at this site show "ND's" for TPH and BTE&X Removal <br /> of most of the contaminated soil may be directly related to this phenomenon <br /> Well 4D, the lower aquifer well, sampled positive for minor levels (all below MCL's) of <br /> Toluene, Ethyl Benzene and Xylene in March, 1991 This well sampled "ND" for all <br /> constituents in April, 1991 Apparently there has been minor contamination of the lower <br /> aquifer, at this site <br /> 6.0 Conclusions and Recommendations <br /> IThe lateral extent of soil contarrunation has been defined by remedial excavation and verified <br /> by laboratory analysis of wall and floor soil samples Water sample analysis from the <br /> Iexcavation showed only minimal impact with Xylenes at 13 µg/L and Gasoline at 81 µg/L <br /> (Table 2) Heavy rainfall runoff from contaminated soils contributed to the groundwater in <br /> the excavation, and probably accounts for the Xylene and Gasoline concentrations noted <br /> above The excavation was backfilled with verified clean soil from another area on the site <br /> I The excavated contaminated soil was stockpiled on-site and has been undergoing bio- <br /> remediation in four lifts All lifts were sampled following plans approved by the San Joaquin <br /> County Public Health Department Lifts 1, 2, 3 have all tested "ND" Lift 4 tested "ND" for <br /> all samples except 4-19 and 4-20 wtuch had Xylene concentrations of 910 and 57 6 ug/kg, <br /> respectively <br /> WHF, Inc recommends closure of this site <br />