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DEVELOPMENT AND EVALUATION OF ALTERNAT~¥ES <br /> <br />characteristics of the fme screenings are so much different than those of the existing coarse <br />screenings. Once the flow passes through the screenings channels, separate grit removal <br />would be used for the expanded facilities. These grit removal facilities would be designed to <br />nnplement new technologies than used in the existing aerated grit chambers. Pretreated <br />effluent from the new facilities could then be routed back to the existing facility where the <br />effluent would be combined prior to preaeration, or the two separate pretreated effluents <br />could be combined downstream of grit removal and routed to primary clarification. <br />Additional grit and screenLngs loadout facilities would be required as part of the expansion. <br />The major new equipment and processes associated with this alternative include: <br /> <br /> Four (4) new fine screens (1/4-inch opening) <br />, Two (2) new screenings washer/compactors <br /> Four (4) Parshall flmes for flow measurement <br /> Four (4) new cyclordc grit separators <br /> Four (4) new grit pumps and cyclones <br /> Two (2) new grit classifiers <br /> Two (2) new screenings/grit hoppers <br /> <br />Alternative 2 - Construct New Pretreatment Facility <br />Alternative 2 considers constructing a new pretreatment facility east of the existing influent <br />screw pumps. This facility would be a new standalone facility that would require separate <br />influent pumping up to the influent channels. All of the technologies used ha Alternative 1 <br />would be applicable to Alternative 2 except all would be located in the new facility and <br />would be independent. Flows in excess of the new facility capacity would be routed and <br />processed at the existing pretreatment facility. The major new equipment and processes <br />associated wiff~ this alternative include: <br /> <br /> Four (4) new fine screens (1/4-inch opening) <br /> Two (2) new screenings washer/compactors <br /> Four (4) Parshall flumes for flow measurement <br /> Four (4) new cyclonic grit separators <br /> Four (4) new grit pumps, concentrators, and classifiers <br /> Two (2) new screenings/grit hoppers <br /> <br /> Results <br /> For Alternatives 1 and 2, the screenings channels and grit separators would be covered and <br /> the odorous air collected and treated in bioscrubbers. The cost comparison developed for <br /> each alternative is relative because it does not include the costs associated with odorous air <br /> ducting and treatment. The relative capital cost comparison and non-monetary comparison <br /> are summarized in Table 6.2.4-1. <br /> <br /> 0_REVI 1 DOC 6-15 <br /> <br /> <br />