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The following sections replace the identically numbered sections in the Revised Draft Work <br /> plan, "Subsurface Investigation / Soil Removal, Naval Communication Station, Rough and <br /> Ready Island, November 1998"by Tetra Tech, Inc. <br /> 3.9 Waste Disposal <br /> All soil designated for backfill will be analyzed for TPH and 20 Title 22 Metals by TTLC and <br /> CA DI-Wet methods. The analytical results will be compared to the background screening <br /> metals for NCS Stockton listed in the following tables. These tables are reproduced from Tables <br /> ES-1 and ES-2a found in PRC Environmental Management's "Comprehensive Long-Term <br /> Environmental Action Navy (Clean I), Final Technical Memorandum Background <br /> Concentrations and Ambient Pesticide Concentrations in Soil, NCS Stockton" October 1997. If <br /> the soils contain concentrations below the screening levels, then the soil will be utilized as <br /> backfill. Soils with levels above these background screening levels will be disposed off-site at <br /> the Forward Inc. Landfill. <br /> TOTAL METALS' SCREENING LEVELS <br /> Metal Soil Type Detection Data Mean Std. Max. Background <br /> Frequency Distribution Screening <br /> Level <br /> (mglkg) <br /> Aluminum Sand 100% Normal 9,759 4,107 17,800 22,080 <br /> Silt&Mineral Clay 100% Normal 20,609 5,764 41,600 37,901 <br /> Org.Clay 100% Normal 30,450 7,709 39,900 53,578 <br /> Antimony All Soil Types 45% None --- --- 1.0 0.942 <br /> Arsenic Sand 100% Lognormal 4.8 3.15 15.7 14.2 <br /> Silt&Mineral Clay 100% Lognormal 10.5 8.19 47.8 35.1 <br /> Org. Clay 100% Normal 14.0 8.27 30.9 38.8 <br /> Barium Sand 100% Normal 111.0 52.4 244.0 268.0 <br /> Silt& Mineral Clay 100% Normal 212.0 61.6 362.0 397.0 <br /> Org. Clay 100% Normal 257.0 72.7 398.0 475.0 <br /> Beryllium Sand 43% --- --- --- 0.49 0.487 <br /> Silt&Mineral Clay 97% Normal 0.745 0.247 1.40 1.49 <br /> Org. Clay 100% Lognormal 0.992 0.158 1.20 1.46 <br /> Cadmium All Soil Types 5% --- --- --- 1.50 0.667 <br /> Chromium Sand 100% Normal 22.1 9.80 39.5 51.5 <br /> Silt&Mineral Clay 100% Normal 40.0 12.3 63.3 76.9 <br /> Org. Clay 100% Normal 63.6 14.6 88.2 107.0 <br /> Chromium VI All soil types 0% --- --- --- --- --- <br /> Cobalt Sand 100% Normal 7.68 3.15 13.8 17.1 <br /> Silt&Mineral Clay 100% Normal 12.7 2.27 16.3 19.5 <br /> Org. Clay 100% Lognormal 15.3 4.05 28.4 27.4 <br /> Copper Sand 100% Lognormal 13.2 9.9 23.8 42.9 <br /> Silt&Mineral Clay 100% Normal 33.8 20.9 138.0 96.5 <br /> Rough&Ready Island 1 Tetra Tech, Inc. <br /> Final Work Plan Addendum December 11, 1998. <br />