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<br />I-IYDROGEOLOGISTS ^ ENGINEERS ^ ENVIRONMENTAL SCIENTISTS <br />October 6, 2009 <br />Rebecca Haug <br />Environmental Administrator <br />City of Ellt River <br />I iUbs Urono Parkway <br />Elk River, MN 55330 <br />R~~~ ~ BEd ~C . <br />T ~ ?~~,g <br />RE: Great River Energy (GRE) Proposal to feed Tire Derived 1~'uel (TDFj at the Elk River <br />Station <br />Dear Rebecca: <br />Liesch Associates, Inc: has reviewed the referenced proposal, the existing air emissions permit <br />for the Elk River. Station, and recent test burn'analytioal data provided by GRE. In Addition; a <br />meeting with,GRE representatives was attended to discuss the~proposal'and test, burn results in <br />more detail on September 2 i ; 2009. ' <br />The existing air emissions permit issued by the Miruiesota Pollution Control Agency (MPCA) <br />dated July 1, 2008 allows for the use of TDF. as a fuel-input at a rate not to exceed 200 tons per <br />day (tpd) in any 24-hour period and 100 tpd on a 30-day rolling average. <br />TDF is proposed to be delivered in covered trailers, off loaded and stored in the existing RDF <br />building. It will be conveyed to the power station using the existing RDF covered conveyor <br />system. Ash from the boilers will be removed and disposed of at the current ash landfill in <br />Becker. No changes in the current air pollution control systems are proposed. <br />A test burn of a RDFlTDF mixture was conducted on August 10-13, 2009. Interpoll <br />Laboratories, Inc. conducted the testing and analytical work. Ash and air emissions analyses <br />were completed. TDF vvas fed at rates from 85-.165 tpd but at an average rate of 135 tpd over <br />the last three days and up to approximately 20% of the total boiler fuel feed by weight. <br />Ash testing for metals was conducted on fly and combined fly and bottom ash. A sample of <br />TDF itself was also analyzed for metals. In addition; an ash sample was analyzed using the <br />TCLP procedure. to determine' :if TDF would change the toxicity of the ash causing it to be <br />regulated as a hazardous waste. 'The results of the ash analyses did not generally show any <br />significant changes to previous RDF ash characteristics or toxicity levels of metals. An <br />exception is zinc, which was present at approxiiYiately twice the previous average ash <br />concentration (from 1991-2008). The TDF feedstock has steel belting remnants present and is <br />believed to be a likely source of the zinc in the ash. <br />www.liesch.com <br />LIESCH ASSOCIATES, INC. ^ 13400 15TH AVENUE NORTH ^ MINNEAPOLIS, MN 55441 ^ 763/489-3100 ^ FAX: 763/489-3 I O I <br />