SITE INFORMATION AND CORRESPONDENCE_FILE 2

Home Browse Search

A GEOMATR[X Ms Mary Meays San Joaquin County Public.Health Services' 29 September 1993 Page 7 easily excavated using standard backhoe and-dewatering equipment, there is no reason. that this contamination can't be cleaned up. We agree with the citation of the LUFT field manual quoted by Alton; ...it is.desirable to clean up soils.and groundwater.to the maximum extent practical to reduce any future risks." The LUFT field manual in•effect at the time.of the excavation required that soil be cleaned up to 10 ppm gasoline and 100ppm diesel'. Alton states that the area surrounding-the site is zoned primarily for commercial/industrial use.-:.: However, unless,deed restrictions are placed.on.the property, other uses, such as residential;.are quite possible and"should be considered in the final remediation plan.. 'Also, some commercial•uses might include a day care center or other sensitive commercial use, which should be consideredin the final plan. Section 1.3.3, Pages 1-14 through 1-17, and Appendix A. - Alton states that the final remediation plan:addresses Hydrocarbon-affected soil and ' Iow-level dissolved-phase hydrocarbons in groundwater. As discussed above, the final remediation plan should address separate-phase hydrocarbons.. - Alton's review of proven remedial'technologies in.Appendix A is completely inadequate for evaluating the feasibility and costs associated with the technologies'..'- Alton places most emphasis-on "economic concerns.`" - . The term "passive remediation is used to describe the recommended remedy in Appendix A, but it is clearly just'a,monitoring program as described in .Section . . - . Section 2.4, Pages 2,3 and 2-4 J - Alton uses its incorrect value-for.groundwater velocity (11.2 ft/yr) to argue that the" site groundwater does not pose a threat to off.-site wells. ' Considering the correct groundwater velocity value is likely to be greater; -this statement should be reevaluated. Alton should also consider the potential for on-site wells screened to 25 feet and'below x to be conduits for cross-coritamination.