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I <br /> Mr.Roger Doak <br /> Coal Ash Pilot Project Proposal <br /> June 26,2000 <br /> Page 7 <br /> 15. We concur that a control trench would provide valuable comparison data. However, <br /> compliance associated with the coal ash trench will be based on water quality testing and <br /> comparing those test results to applicable standards. Varra Companies was awarded a research <br /> grant for the column study and permit phase and will apply for a grant to conduct the pilot test. <br /> If the grant is awarded the comparison testing will likely be performed; however, this testing <br /> cannot be guaranteed at this time. <br /> 16. The radioactivity in coal ash has been documented by the EPA and the USGS. A Fact Sheet <br /> regarding this subject is included in Attachment G. Analytical data for Fly and bottom ashes <br /> from PSCO's Cherokee plant (ashes used in the leaching tests were obtained from the USGS) <br /> are included in Attachment G as well. The radioactivity is consistent with typical radio suits <br /> documented by EPA and the USGS. In EPA's March 1999 report to Congress states that <br /> "Exposure from direct contact, inhalation and ingestion were estimated to fall below natural <br /> background radiation exposure levels even for a worker standing on the ash pile". EPA <br /> eliminated radionuclides from further study based on ongoing and previous studies. Uranium <br /> was analyzed as part of the modified column leaching study. As the data show, dissolved <br /> uranium concentrations were lower in the leachates than in the water used as the leaching <br /> medium. This shows that the ash is not contributing uranium at levels higher than background. <br /> In reply to Mr. Niswonger's letter of May 3, 1999 we offer the following comments and address <br /> his issues by item. <br /> I. Compositional data presented in our work plan were for ashes obtained from the PSCO <br /> Cherokee plant. Analytical data for the Cherokee plant ashes were provided; however, do not <br /> correspond with the ashes used in the leaching tests and were submitted to provide an overview <br /> of coal chemistry. Analytical data for the ashes used in the CSU and CGRS leaching <br /> experiments are provide in Attachment D and analytical data submittal. <br /> 2. The ash proposed for use in the Varra Test Project in Weld County will come from the <br /> Cherokee Generating Station in Denver, Colorado. The plant has four pulverized coal-fired <br /> boilers all of which burn coal from Moffat, Routt or Delta counties. These mines include West <br /> Elk, TwentyMile, Powderhorn, and ColoWyo. This coal is supplied under long term contracts <br /> that extend to the year 2007 or later. Under the terms of the contracts, the coal is required to <br /> meet certain specifications including Btu rating, ash content, mineral analyses, sulfur content, <br /> moisture, etc. Therefore, the chemical and physical properties of the coal (and resulting ash) do <br /> not change significantly from year to year. Comparisons of analytical data completed in the <br /> early 1990s with recent data indicate little variation in any of the ash constituents. These mines <br /> have supplied coal to PSCo for many years and the coal itself changes little over the course of <br /> time. Similarly, the ash resulting from the combustion of the coal exhibits little change as well. <br /> Analyses performed in 1990 and in 1999 are very similar with few variations. <br /> The coal is delivered in unit trains and stockpiled at the plant for burning. Coal is crushed <br /> prior to storage in silos above each coal mill. Multiple coal mills serve a single boiler and the <br /> mills further reduce the coal to particles of powder-like consistency. The coal is ignited in the <br /> boiler and heat generated. Heavier particles of unburned coal or inert matter fall to the bottom <br />