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59 <br /> Geoscience believes that the areal extent of soil contamination has been,adequately defined by <br /> the work done to date. <br /> Section 1.3.1, Pages 1-11 through 1-13 <br /> First Bullet Item <br /> I� <br /> The LUFT field manual does not specify cleanup levels for soil or ground water contamination. <br /> Cleanup levels for soil are left to the discretion of the local oversight agency and the Regional <br /> Water Quality Control Board. Therefore, Geomatrix' statement that the "LUFT field manual <br /> in effect at the time of the excavation required that soil be cleaned up to 10 ppm gasoline and <br /> 100 ppm diesel' is incorrect.- j <br /> Second Bullet Item <br /> Alton Geoseience does not agree with Geomatrix' statement that "...other uses, such as <br /> residential, are quite possible and should be considered in the final remediation plan. " A <br /> change in zoning from commercial/industrial use is not consistent with the City of Tracy zoning <br /> plan. According to the City of Tracy Planning Department, day care centers are not permitted <br /> in areas zoned for commercial or,industrial use (Villa, 1993). The exposure scenario evaluated <br /> in this assessment was selected, in part, on the basis of the proposed development of the <br /> Stonebridge Industrial Park. If an-alternate land use is proposed for the site, an alternative risk <br /> analysis, based on the site-specific zoning requirements, can be evaluated. However, a change <br /> in site use from commercial to residential will not result in any substantive changes in the <br /> qualitative results of the risk assessment. ' <br /> - I <br /> Section 1.3.3, Pages 1-14 through 1-17, and Appendix A <br /> First Bullet Item <br /> There is no evidence that separate-phase hydrocarbons exist at the site. This statement is based <br /> on the following observations: s <br /> • The highest concentrations of petroleum hydrocarbons in soil (AW-12 (W 10 fbg; 570 <br /> ppm and 3,700 ppm TPH-G'and TPH-D, respectively) are below the concentration which <br /> would suggest residual hydrocarbon saturation of soil. <br /> • Concentrations of petroleum hydrocarbons detected in ground`water are below the <br /> concentration which would suggest maximum hydrocarbon solubility in ground water. <br /> 3 <br /> • Separate-phase hydrocarlions have not been detected through visual observation of <br /> ground water samples collected during ground water monitoring and sampling activities. <br /> 9 <br /> i <br /> I <br />