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Mr. Rogcr Doak <br />Coal Ash Piloi Project Proposal <br />March I4, 21x10 <br />Pagc 2 of 2 <br />3. Background sampling has been performed on three occasions and the analytical results are <br />presented in Attachment B. A review of analytical data show analyze concentrations as <br />recommended by Mr. Ken Neiswonger of CDPH&E. It is anticipated that a minimum of four <br />sampling events will be conducted to determine background water quality. <br />4. CGRS has amended its analytical parameters to include alkalinity as carbonate and bicarbonate, <br />phosphorus, titanium, molybdenum, mercury, and uranium. Total cyanide was eliminated from <br />the suite, as it was not detected above any standards in any of the samples submitted during the <br />previous experiments. <br />5. As requested a QAPP for the Varta Coal Ash Project -Leaching Test is presented as <br />Attachment C. <br />6. It is our opinion that coal ash does not undergo significant physical or chemical changes with <br />time under atmospheric conditions. Calcium oxide (lime) can combine with carbon dioxide <br />to form calcium carbonate, but under dry (atmospheric) conditions this process is extremely <br />slow. Saturated paste tests using fresh ash and ash in excess of a year old (stored in a dry <br />state) resulted in negligible pH differences, which indicates the transformation of calcium <br />oxide to calcium carbonate is not prevalent. <br />Thermal transformation of major inorganic phases during coal combustion creates mineral <br />assemblages that are fairly stable when dry. When saturated with natural waters, secondary <br />mineral phases can occur as a result of the dissolution of elements in soluble salt or oxide <br />forms and reprecipitation of those elements into stable mineral assemblages. These <br />secondary mineral assemblages are generally highly insoluble under most natural conditions. <br />The purpose of this project is to determine the elemental leaching capability of unweathered <br />coal ash in contact with natural waters. All of the ash used in the proposed pilot study will be <br />reFlective of the ash used in the column study. As such, curing is not needed for this study. <br />if you have any questions regarding this letter or enclosures, please contact me at (970) 493-7780. <br />Sincerely, <br />CGRS, INC. , <br />~ Joby lr. Adams, P.G. <br />'nc' aUHydrogeologist <br />Attachments <br />cc: Mr. Chris Varta - Varra Companies <br />Mr. Dave Goss - PSC <br />dull',tin'Of~iHcckYltC3'Ilfid~Oatttttf"-Eiealtll•Depart[nent~ <br />Ms. Christina Kamnikar -Colorado Division of Minerals and Geology <br />