SITE INFORMATION AND CORRESPONDENCE_1993-2003

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Draft Soils FS Memorandum 11- 14 September 1993 DDRW, Sharpe lead despite the presence of lead contamination just above the water table in the boring sample. j. Page 2-9, Section 2.2.2, Cleanup Levels Based On Protection of Ground Water: See Major Comment 1. k. Page 2-19, Section 2.2.2, Designated Level Methodology: See Comment 6 of the CVRWQCB Comments on the February 1992 Draft Soils FS. I. Page 2-19, Section 2.2.2, Economic Analysis: This section states that another groundwater treatment system will be operating in the Central Area by 1993. This should be changed to 1994. M. Page 2-22, Section 2.2.3, Presentation of Potential Cleanup Levels: The number for the cleanup level for TCE in soils is incorrect, and should be 0.05 mg/kg or 50 ppb. In addition, page 2-20 presented the cost effective treatment level for TCE contaminated soil at 44 µg/kg, and on page 2-22 this same number is presented as 44 it These units are in ppb and ppm, respectively, and therefore inconsistent. The Draft Final FS should be revised to reflect accurate cleanup levels and units. n. Page 2-24, Section 2.3.5, Historic Sites and Archaeological Findings: The last sentence should state that sixteen of the sites are located in Stockton, approximately 9 miles north of Sharpe, not south. o. Page 5-2, Section 5.1, Lead and Chromium Contaminated Soil: We do not concur that only the SWMU PS#4 is the only area which requires remediation in the Central Balloon Area. See Major Comment 1. This section does not discuss remediation of sites in the South Balloon Area (A#27, PS#7, S#29). It does not appear that the lead and chromium contaminated sites in the South Balloon Area will be considered for remediation, this is unacceptable (see Major Comment 1). The Draft Soils FS does not provide sufficient information to support no further action at these sites. p. Page 5-3, Section 5.1, Lead and Chromium Contaminated Soil: This section states that Figure 1.4-6 identifies all areas on the North Balloon Area which exceed the cleanup level of 500 µg/g of chromium. The figure referenced should be Figure 1.4-8. q. Page 5-29, Section 5.1.4, Alternative 4B - Removal and Disposal - Offsite Landfill: This section states that approximately 9,900 cubic yards of contaminated would be excavated from the site and transported offsite (probably Kettleman, CA) for final soil disposal. It also states that it is estimated that completion of this remedial alternative would require 4 days. The estimated time of 4 days to complete this remedial alternative appears unrealistic. The 4 day estimate would require over 123 truck loads of 20 cubic yards each load per day to remove this volume of material, not including the importing of backfill. A more realistic estimate