Resolution No. 4793 - Laserfiche WebLink

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MWMC FACIUTIES PLAN TABLE 6.2.4-1 Summary of Pretreatment Expansion Alternatives Comparison MWMC Famlrties Plan, Eugene. Spnngfield Capital Cost Alternative (millions of dollars) Non-Monetary Ratinga I - Expand Existing Pretreatment Facility $12.8 21 2 - Construct New Pretreatment Facility $17 19 Notes: a Non-monetary score is out of a poss~bte maximum score of 30 points. Capital costs associated with const~action of a new pretreatment facility are approximately 30 percent higher than for the expansion of the existing facility. The non-monetary evaluation of the mo alternatives indicates that expansion of the exis~_qg pretreatment facility is shghtly more favorable than constructing a new facility. Both alternatives will have 160 mgd of capacity to minimize operation of the existing pre~reatment facility, which would only need to be brought online for peak flows. It was assumed that the new pretreatment facility would have full grit removal capacity. As more detailed planning and design efforts proceed for the expansion of the exisQng pretreatment facility, both of Lhese assumptions should be evaluated more closely. It may be more cost-effective to provide only the required 102 mgd of additional capacity and provide flexibility to bring the existing pretreatment facffity online and offline more frequently, although this would be extremely labor-intensive from an O&M standpoint. An alternative to providing grit removal during pretreatment would be to degdt thin from the clarifiers. This avoid construction o£ removal primary sludge primary may facgities in the pretreatment expansion. As part of the approach to expand primary clarffier capaci~, the abihty to pump ti,in sludge and thicken the primary sludge outside of the clarifiers will be assessed. Grit accumulation in the primary clarifier centerwells is an issue of concern that would have to be addressed if the degritting primary sludge approach is pursued. Based on the alternatives analysis, it is recommended that Alternative 1, expansion of the existing pretreatment facility, be carried forward for faciLity planning purposes. Further investigation of pretrea~ent capacity and grit removal will be carried out during predesign. Upon further refinement of the pretreatment expansion, selection and comparison of specific equipment associated with the selected alternative will be evaluated more comprehensively. 6.2.5 Odor Contro It is anticipated that the WPCF will need to increase its odorous air treatment system to address the projected increase in air flow rates resulting from the addition of new process units throughout the plant. The existing odor control system consists of a three-cell, organic media biofilter with a design capacity of 18,000 cubic feet per minute (ff~/mi~ute) and a connected capacity of 15,000 ff3/minute. The new odor control system would have sufficient capacity to treat the existing odorous air flow rates and an additional 23,000 anticipated for the new process units. Representative sLzes for new facilit-zes requiz-Lng odor control have been selected and the resulC_~g air flow rates calculated using the applicable M~c_60_REVI 1.DOC,