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Mr.Roger Doak <br /> Coal Ash Pilot Project Proposal <br /> June 26,2000 <br /> Page 9 <br /> 7. This table was generated not to indicate anticipated leaching potentials of various materials but <br /> to provide a comparison of elemental compositions of coarse or unfiltered leachates of various <br /> materials against recognized numerical standards. An indirect purpose of this project is to <br /> compare coal ashes to material considered inert, and in our opinion Table 6 strongly indicates <br /> that coal ash should be given consideration as an inert material when compared to recycled <br /> materials. <br /> 8. As was demonstrated by the modified leaching tests, coal ash can be deposited in saturated <br /> conditions with minimal effects. EPA has never contemplated wet management techniques that <br /> are being proposed and probably has never considered that isolating coal ash from the <br /> weathering cycle may be counter productive. Studies in the Netherlands indicate that the <br /> weathering process inhibits heavy metal leaching in coal Fly ashes and a paper supporting this <br /> conclusion is presented as Attachment J. <br /> The vast difference in permeabilities of the native soil and the ash is what we believe what will <br /> allow the safe use of ash as fill material in a saturated environment. Groundwater will saturate <br /> the ash with a minimal volume of water passing through the ash deposit. The interaction of <br /> natural water and the ash will induce weathering and secondary mineral formations, which will <br /> hinder leaching processes. As shown with model results, boron and selenium levels, without <br /> considering retardation, should be below background or any regulatory levels within 50 feet of <br /> the trench. As such the potential for adverse impact for this project is considered minimal. <br /> 9. A QAPP was submitted for the leaching experiment and an amended QAPP for the pilot <br /> project is submitted with this correspondence. <br /> 10. We agree with Mr. Niswonger's comment. <br /> The results of the modified column leaching test demonstrate that coal Fly ash can be placed in a <br /> saturated environment without creating significant environmental risk. The pilot project poses no <br /> threat to adjacent water users as a result of hydraulic modifications and water quality issues should <br /> not be an issue any significant distance downgradient of the trench. Varra companies will be <br /> required to provide financial assurance and if required abatement activities will be implemented. <br /> The proposed monitoring program is rigorous and will provide early warning to any possible <br /> adverse impacts. Analytical data show that the average concentration of elements in column <br /> leachate samples are below regulatory standards. This combined with analytical advection and <br /> dispersion solutions support a conclusion that adverse impact to waters of the state is unlikely. The <br /> data this project will provide are invaluable to the regulatory and scientific community, and will <br /> provide insight to issues not addressed by EPA or other scientific studies. It is our opinion that the <br /> data presented to date support a finding that the proposed pilot project is technically feasible. <br />