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In addition to the digester volume required, additional sludge storage space is <br /> needed to meet the design conditions. In order to provide 180 days of storage for <br /> biosolids at 4 percent solids, the Elk River WWTF would need an additional 2.8 <br /> MG of sludge storage for Design Option No. 1 and 3.8 MG for Design Option <br /> No. 2. <br /> Do to the excessive land requirements for the required digesters and sludge <br /> storage, expansion of the anaerobic digestion system is not viewed as a feasible <br /> option and will not be analyzed any further in this report. <br /> 4.3.3. Heat Drying <br /> The heat drying process for biosolids treatment consists of aerated biosolids <br /> storage, dewatering, and heat drying. To implement this process at the Elk River <br /> WWTF, aeration equipment would be added to the existing biosolids storage <br /> tanks to provide aerated storage. A biosolids processing building would be <br /> constructed to house the dewatering and drying equipment as well as storage for <br /> the dried biosolids. The end product would be roughly 90 percent solids and <br /> would be stored until land application. Design of the heat drying system would <br /> include provisions to meet both design conditions. The location of the proposed <br /> biosolids building is shown in Figures 4.1 and 4.3 while a biosolids process flow <br /> diagram for this option is provided in Figure 4.5. <br /> 4.3.4. Regionalization <br /> Regionalization for biosolids treatment could be done with the City of Buffalo for <br /> contract biosolids treatment. In this partnership the City of Elk River would be <br /> responsible for hauling biosolids to the Buffalo WWTF which could be contracted <br /> out to a licensed biosolids hauler. The City of Elk River would also have to pay a <br /> set fee for treatment of biosolids based on total dry tons of sludge treated. <br /> City of Elk River—T12.104758 Page 26 <br /> Wastewater Treatment Facility Plan Prepared by Bolton&Menk,Inc. <br />