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Metropolitan Wastewater Management Commission Capital Improvement Program <br />AERATION BASIN IMPROVEMENTS – PHASE 2 <br />Description: <br />Aeration Basin (Phase 2): Recent recommendations are to evaluate and consider <br />improving some of the secondary treatment systems. Upcoming early work items to be <br />evaluated are changes to the existing air piping, change to the diffuser/mixing systems, <br />and consider upgrading older blower equipment. Future upgrades include adding step <br />feed, anoxic selectors, and fine bubble diffusers to 4 of the 8 cells of the aeration basins <br />and make hydraulic improvements. This project was originally the North Aeration Basin <br />Improvements project; however the Phase 1 study/design phase showed that <br />improvements to the four eastern most basins as a first phase would allow for better <br />hydraulics and more operational flexibility. <br />In January 2016, the project scope and cost (estimate $750K in 2015) increased to <br />include replacement of existing aeration basin gates, valves and spray system. <br />Status: <br />Planned for future implementation. <br />Justification: <br /> Improve secondary treatment process. Increase the dry weather aeration basin treatment <br />capacity with respect to ammonia (with nitrification) and increase the wet weather <br />treatment capacity. <br />Project Driver: <br />National Pollution Discharge Elimination System (NPDES) permit includes ammonia <br />limit requiring nitrification in dry weather and expansion of wet weather capacity to treat <br />wet weather flows to meet NPDES permit monthly and weekly suspended solids limits. <br />Project Trigger: <br />Address water quality requirements (need to evaluate the requirements based on the <br /> <br />MWMC next NPDES permit renewal). <br />Project Type: <br />50% Capacity; 50% Performance. <br />Improvement <br />SDC Eligibility: <br />58.7% <br />Estimated Project Cost: <br />$16,100,000 <br />Estimated Cash Flow: <br />FY 19-20 = $1,000,000; FY 20-21 = $1,475,000; FY 21-22 = $6,400,000; <br />FY 22-23 = $6,550,000; FY 23-24 = $675,000 <br />Prior2017-18 <br /> Expenditure/Category:YearsEst. Act.2018-192019-202020-212021-222022-23Total <br /> Design/Construction$0$0$0$1,500,000$4,600,000$6,000,000$4,000,000$16,100,000 <br /> Other$0$0$0$0$0$0$0$0 <br />Total Cost$0$0$0$1,500,000$4,600,000$6,000,000$4,000,000$16,100,000 <br />Page 50FY 18-19 BUDGET AND CIP <br /> <br />