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Al Jesena - 8 - 1 March 2000 Draft RI for OU#3 NCTS, Stockton VOLUME IV Appendix NI—Statistical Evaluation of Waste Extraction Test and Subsurface Soil Metals Analytical Data 1. COPCs were identified but dismissed because they were "statistically different" from the background population. Please provide details explaining this determination by the Navy. 2. We reserve the right to further review details on the Statistical Evaluation of Waste Extraction Test and Subsurface Soil Metals Analytical Data with the next Draft RI report submittal. This decision is based upon the organization of the data. For instance, Table K-2 for IAS-03/04, Soil Inorganic Analysis Report includes total and WET results. Sample 187WETI3405S2 (Table K-2, 12/17/98, 4 to 7 feet) shows <0.46 for antimony. Table K-4, WET shows <1.2 for the same sample location. Because we do not have the raw data, we cannot check these results. Please rectify all tables as part of the next revised Draft RI and revisit any decisions related to this database. Appendix N. Water Quality Assessment Methods 1. Section 1.1.1.3. Natural Occurrences. We disagree that nonpetroleum hydrocarbons are naturally occurring. As above, please provide chromatograms fingerprinting these constituents. 2. Section 1.2.1. Pesticides have been detected in WET extracts from soil samples collected below the water table. The Navy concludes that these results do not represent contamination because pesticides were not detected in downgradient wells. Monitoring wells are contaminated with VOCs from a plume associated with site IAS-16 and Site 39 that is east and downgradient from IAS-03/04. The wells are also 250 feet east of the sample locations. Because of the complex, dynamic hydrogeology in the landfill area, it is difficult to predict what wells are downgradient to each individual site. In order to verify whether groundwater has been impacted from the landfills, hot spots, or soil, we recommend that the Navy propose a discrete groundwater sampling plan for all constituents that are found in the WET analysis that may pose a threat to groundwater and surface water quality. Past discrete groundwater samples were only analyzed for VOCs. Appendix S. Fate and Transport Modeling Because there is theoretically no attenuative capacity in 4—6 feet of soil above the groundwater table, we do not agree that modeling should be used to evaluate the fate and transport of inorganics. As discussed in our comments above, we prefer that discrete groundwater samples be pursued to verify whether water has been impacted by all COPCs. Additional monitoring wells should be installed to monitor whether landfills are or continue to be a source for polluting waters of the State. Nevertheless, we are providing comments on the use of VLEACHSM for your consideration. The following comments also anticipate the need for further explanation as to how data was manipulated and why/how particular assumptions were made by the modeler: