Resolution No. 4793 - Laserfiche WebLink

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MWMC FACILITIES PLAN clarifiers up to their modified capacity of 134-165 mgd. Pretreated flows in excess of this would be pumped directly the aeration basins, taking advantage of the large volume and long detention time. PE from the existing primary clarifiers in excess of the secondary treatment capacity would be diverted arotmd secondary treatment with a new pump station, resulting in primary and secondary treatment processes operating in parallel. The primary and secondary effluents would be disinfected separately and blended prior to discharge to the river. Figure 6.6.2-3 shows the process flow schematic for system alternative 5. ~ 30 mgd through Tertiary Filtration Secondary Flow Management ~ 160 mgd 4~~ ~ 160 mgd through Primary / Secondary Primary Flow Ma~gement ~ ~ FIGURE 6.6.2-3 Pro.ss Row Diagram for System Alternative 5--Parallel Pfima~ ~nd Seconda~ Treatment MWMC Facilities Plan, Eugene-Springfield 6,6,3 Matrix Evaluation Evaluation of the system alternatives includes both a relative cost comparison and a non- monetary evaluation. Improvements that are common to all system alternatives were not considered in the cost comparison; only improvements that were tmique to each system alternative were included. The results from the relative cost and non-monetary comparisons are summarized in Table 6.6.3-1. TABLE 6.6.3-1 Summary of Peak Flow Management Alternatives Companson MWMC Facilities Plan, Eugene~Spnngfietd Capital Cost System Alternative (millions of dollars) Non-Nlonetary Rating" 1 - No Action $0 16 2 - Additional Pnmary and Secondary Cladfiers, Aeration $57 17 Basin 3 - Additional Pnmary Clarifiers $31 20 4 - High-Rate Clarificabon $25 20 5 - Parallel Primary and Secondary Treatment $11 23 Notes: '~ Non-monetary score is out of a possible maximum score of 30 points. 6.54 MWMC_60_REV'f I DOC