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The UV disinfection system for Elk River's WWTF is designed at 65% UV <br />transmittance with dose of 30 mJ/cm2 for 7.0 MGD flow. During the study period the <br />lowest observed UVT was 45%, which is well below the design value. Trojan <br />Technologies (manufacturer of existing UV system) was contacted to receive <br />recommendation for UVT at the City's current flow of 1.3 MGD. Trojan would not <br />give any recommendation for UVT at flows lower than 7.0 MGD and stated that if the <br />UV disinfection system runs below the designed UVT of 65%, they would not <br />guarantee the performance of the system. <br />However, based on the City's experience of meeting fecal coliform results while <br />running at 50% UV transmittance with a trickling filter plant and Bolton and Menk's <br />experience with similar application, we recommend that Elk River's WWTF can <br />handle a leachate flow that equals to approximately 2% of the City's average flow <br />and still maintain proper UV disinfection of approximately 50% UV transmittance. <br />The 2% ratio currently equates to a leachate volume of approximately 25,000 to <br />27,000 gpd. It should be noted that as the flow to the city's WWTF increases, the <br />City should be able to accept additional leachate due to increased dilution factor. <br />If the City of Elk River and Waste Management decide to enter into a treatment <br />agreement for the City to accept leachate, following are a few items that need to be <br />considered: location of disposing leachate and odor control, the recommended <br />leachate flow (ratio of leachate to city's flow), and additional biosolids generated. <br />Prepared by: Bolton & Menk, Inc. Conclusion <br />Waste Management/Elk River Leachate Pilot Study I T21.109643 Page 18 <br />