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GEOMATRIX Mr. Philip Isorena California Regional Water Quality Control Board September 14, 2000 Page 6 As discussed in the response to Item E, CEMC will provide an estimate of the mass of residual petroleum in soil and groundwater and discuss mass reduction and estimated time to remediation in the final closure request document. Comments from RWQCB,Fresno Branch Office The RWQCB Fresno Branch Office comments regarding the Draft Site Closure Request are presented below in italics, followed by our response. We have reviewed the subject document and conclude that the sites should not be closed as low risk since: I. No source removal is proposed at the sites. Most petroleum sites are closed with the assumption that natural bioremediation will cleanup wastes that remain in soils/groundwater. However, natural bioremediation will not be effective at these sites with the large mass of petroleum that is proposed to be left in soils/groundwater. Source removal, including "hot spot" removal, should greatly increase the effectiveness of bioremediation and decrease cleanup time frames. The document indicates that excavation is a cost prohibitive alternative and would be $8 million per site. However, the cost estimates appear to be too high and it is unclear if reuse of impacted soils was used in the estimate. Crude impacted soils excavated from other petroleum sites have been beneficially reused for tank berms and road base. As shown in Table 1 of the draft closure request, it would cost approximately $8 million to perform complete removal of affected soil because it would be necessary to re-route Byron Road, the railroad, and the drainage canal and to de-water the excavation to remove affected soil beneath the water table. In the final closure request, Geomatrix will provide additional detail to support our cost estimate. As described in the draft closure request, removal of easily accessible soil (e.g., soil not beneath Byron Road, the railroad, or the canal) could be performed for a lower cost($1.5 million); however, a significant mass of petroleum will remain and the time frame to fully complete remediation of biodegradation byproducts in groundwater will not be significantly decreased from the remaining alternatives. RWQCB suggests "hot spot" removal to expedite the cleanup time frame. When soil is affected by petroleum at the site, TPH concentrations (quantified as crude oil) are generally a few hundred to a few thousand milligrams per kilogram. As such, no particular"hot spot" can be identified. RWQCB also suggests consideration of reuse of affected soil for tank berms and road base. Reuse was not considered because no such reuse options are available at the Bruns site. If reuse options were available, the reused soil would still be in proximity to the water table, which occurs at approximately 7 feet below ground surface (bgs). Therefore,