SITE INFORMATION AND CORRESPONDENCE_FILE 1

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Mr. Timothy VanDomelen - 2 - 17 September 2009, J.R. Simplot, Lathrop technologies are available for both soil and groundwater impacted with ammonium, nitrate, and sulfate. One or more may be appropriate for the Lathrop site and may prove to be more effective than the alternatives presented in the FS. For example: • At the J.R. Simplot facility in Winton, a pilot study is underway to evaluate the effectiveness of treating nitrate and ammonium in extracted groundwater with carbon, prior to reinjection. • Bioreactors for denitrification of groundwater have been employed successfully at sites impacted by fertilizers. • In-situ technologies for soil, such as application of wood mulch to high- ammonium surface soils, can effectively denitrify soil. Application of primer compounds to soils may promote reducing conditions and the decomposition of both nitrate and sulfate compounds. Under the proper conditions, alternate soil and groundwater cleanup methods may result in greater mass reductions and a more efficient and cost-effective cleanup overall than the remedial alternatives selected in the FS. We request that you provide additional detail on in-situ remedial options as part of an addendum to the FS. 2. We support reuse of extracted groundwater as part of a cleanup plan. Land application of water containing plant nutrients, as described in the extraction and reuse remedial alternative, is potentially a beneficial use and may be an acceptable remedy. In order for LIS to evaluate this option, please provide information on the proposed crop(s) to be planted, a proposed application rate, expected nutrient concentrations in applied water, and an analysis of the total average concentrations of sulfate, nitrate, and ammonia that can be absorbed by these plants. Please provide this analysis in an addendum to the FS. 3. Geomatrix does not explain in the FS the treatment train for extracted groundwater, or how water can be segregated into "brine" and "suitable for irrigation," as described in Section 6.1.3. Please provide additional details on the proposed process that would allow extracted water to be segregated. 4. Use of the process water ponds to store extracted groundwater will require a revision to the Waste Discharge Requirements No. 97-229. Please take into consideration, it would likely take a minimum of 3 months to complete public notice and Central Valley Water Board Hearing procedures, when evaluating the feasibility of this alternative. 5. The Total Designated Levels (TDLs) for.inorganic constituents in soil are presented in Appendix E. Leachability factors for ammonia, nitrate, and sulfate were calculated using soil and Waste Extraction Test analytical results. Calculations of TDL assumed an environmental attenuation factor of 10 for ammonia, and 1 for both nitrate and sulfate. Please provide an explanation for use of an attenuation factor of 10 for ammonia at this site given the concentrations of ammonia in groundwater.