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i Project No. E6576.001 Additional Groundwater Sampling/W. Clover Rml'ti 22 March 1995 RECOMMENDATIONS 1 - The results of analysis of the borings, monitor well, and confirmatory samples given E in Tables 1 through 3 indicate that only insignificant levels of contamination remain in the area where the three USTs were removed. These have been quantified herein. It is, therefore, the opinion of TERRASEARCH, ine., that closure be permitted at the Site after the actions below are completed. l Final Cleanup: Clean import sand and gravel will be used to fill the excavation to above the water rtable. The approximately 100 cubic yards segregated clean overburden stockpile will then be L placed in the excavation. During the backfill operation, the excavation will be dewatered; and a backhoe will be used to remove as much of the below-water trim and sluff(see Figure 3) as isp racticable. This material will be added to the "contaminated" stockpile. The backhoe, or a small loader/dozer will then push the backfill material into the excavation, working from the sides. Once the excavation has been backfilled above groundwater level, the loader or backhoe can break back the bank so that the loader, with a vibrating roller, can compact the remaining material, as the import and clean original sand is brought up to grade in layers. f Disposal of Stockpile of "Contaminated" Soil: j The existing 200 cy of material, as well as up to 30 cy of material added from the backfill operation described above, contains very little diesel. The first (most westerly) approximately 100 cy of material is almost all original sandy backfill material. The remainder consisted of randomly mixed sand and clay. Since only the westerly portion of this stockpile, as defined by the dashed line in Figure 5, showed any contamination, this portion shall be hauled by a certified hauler to either the Forward landfill in Modesto or the Vasco Road landfill near Livermore. The easterly portion shall be spread on the surface of the Site in a layer not exceeding 2 inches in thickness. Page 11 TERRASEARCH, INC.