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Table ES-2.Concept Level Capital and O&M Costs for Ultimate Demand <br /> Approach 2 Approach 4 <br /> Approach 1 Regional 3 ppItem Re Tonal Groundwater [Approach <br /> Con'unctive Status Quo <br /> g � Lime <br /> Surface Water`4 Lime Use <br /> go Softening <br /> Softening <br /> Capital Costs <br /> g _ <br /> 2040 Capital Costs $21790009000 $26090009000 $187,0009000 $190,0009000 <br /> Distribution System qm <br /> Phase D, Scenario 1 $67,000,000 $67,0002000 <br /> Phase D2, Scenario 2 $62,0003000 <br /> WTP and Wells $164,000,000 $2721 000,000 $2021 000,000 $4101 000,000 <br /> Capital Cost Total' $44890009000 $59450009000 $456,000,000 $600,000,000 <br /> Annualized Capital Cost $16 100 000 $21 500 000 $16 400 000 $21 700 000 <br /> (60 year) ' <br /> O&M Annual Costs <br /> WTP O&M $17500,000 $161400 3 000 $151 600,000 $18,1001 000 <br /> Booster Station O&M $440,000 $4407000 $4407000 <br /> WTP Repair& $5 900 000 $8 900 000 $6 000 000 $12 1 00 000 <br /> Replacement (2%) ' <br /> Distribution Repair and $1 600 000 $1 300 000 $1 600 000 <br /> Replacement (1%) ' <br /> O&M Cost Total' $25,000,000 $27,0009000 $2490009000 $30,0001000 <br /> Total Annualized Cost' $419300,000 $4855009000 $40,4009000 $51,7001000 <br /> Costs based on 2020 dollars; no escalation to date of construction. <br /> Summary of Findings and Implementation Considerations <br /> Key takeaways from this concept level study of alternative approaches to a Northwest Metro area <br /> regional drinking water supply system include: <br /> • The average day water demand in the Northwest Metro is projected to increase from 3.3 MGD in <br /> 2015 to 7.8 MGD in 2040 (140% increase). <br /> • The ultimate average day water demand in the Northwest Metro is 29 MGD (approximately 800% <br /> increase from 2015). <br /> • If the Northwest Metro cities continue to utilize only groundwater to meet water demands, an <br /> additional 54 wells will likely be needed to meet ultimate demands. A 2016 MCES report indicated <br /> drawdown in the Tunnel City-Wonewoc aquifer in 2040 when demands are only 27% of the ultimate <br /> demands. It is possible that the aquifer cannot sustain the ultimate demands of the Northwest <br /> Metro. <br /> • The Mississippi River has sufficient water quantity to serve the Northwest Metro communities. The <br /> water quality in the Mississippi River appears to be acceptable for a conventional surface water <br /> treatment plant. St. Could, St. Paul, and Minneapolis utilize the Mississippi River as their source of <br /> drinking water. <br /> • A regional surface WTP has the advantages of being a cost effective approach, eliminates the need <br /> for numerous addition wells, increases groundwater sustainability, provides fully softened water, <br /> and reduces chloride discharges to the Mississippi River. The disadvantages of a regional surface <br /> WTP is that it changes water taste and odor and relies heavily on one water source. <br /> • A regional lime-softening groundwater WTP has the advantages of providing fully softened water <br /> and reduces chloride discharges to the Mississippi River. The disadvantages of a regional lime <br /> softening groundwater WTP is that it is one of the most expensive approaches evaluated, may not <br /> be feasible due to groundwater drawdown, and relies heavily on one water source. <br /> Page—ES-7 I METROPOLITAN COUNCIL <br />