FIELD DOCUMENTS AND WORK PLANS 2004-2014

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Steven Ross and Siddharth Sewalia November 17,2008 DTSC/CRWQCB Total Nitrate Hexavalent Iron Manganese TDS TOC Sample Sulfate Arsenic Dissolved (pg1L) (pg/L (mg/L) Well I.D. Date as N (mg/L) (pg/L) Chromium Chromium (mg/L) (mgtL) (pg/L) (PgtL) 7/10/08 1.4 57.1 <5 3,300 3,240 298 20 367 <1 MW-206 10/22/08 4.6 278.0 <5 24,000 25,100 <100 60 993 3.5 The change in hexavalent chromium concentration reported in MW-206 is likely the affect of the soil flushing beneath the retort pit. The increase in hexavalent chromium in MW-206 supports the process that the flushing wells have mobilized elevated hexavalent chromium from the soil column beneath the retort pit area down to groundwater, as designed (attached Figure 7). The proposed supplemental horizontal injection treatment will consist of injecting approximately 90,000 gallons of treatment solution with the same mixture used for the deep vertical boring injections throughout the site (2% ethanol, 3% calcium polysulfide (CaSx), and 95% water by volume). The proposed mixture will be more concentrated than the initial horizontal injection treatment solution, which consisted of a mixture of 1% ethanol, 1.5% CaSx, and 97.5% water by volume. MWH has initiated preparation for this supplemental horizontal injection event, and would like to schedule this work as soon as possible due to the increases in hexavalent chromium concentrations moving downgradient from the former retort pit area. MWH is requesting an expedited response and approval to perform this injection from the CRWQCB and DTSC. Please do not hesitate to contact me at (916) 418-8354 if you have any questions regarding this matter or the project. Sincerely, MWH Americas, Inc. Tony P. Mikacich Project Manager Attachment: Figure 2—Site Plan Figure 7 —Process Flow Diagram cc: Dan McGrade, SPX Corporation Jim Lingo, SPX Cooling Technologies Steven Stuart,Dudek&Associates, Inc. Amy Wilson,TRC Harlin Knoll, SJC-EHD Page 2