Agenda - Council Work Session - 09/13/2022

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7 • Approach 1: Regional Surface Water Treatment Plant • Approach 2: Regional Lime Softening Groundwater Treatment Plant • Approach 3: Regional Conjunctive Use System (Surface Water Augmented with Groundwater) • Approach 4: Status Quo (communities construct individual lime softening groundwater treatment plants) So that similar treated water qualities were being evaluated, Approach 2 and Approach 4 assumed that the communities would construct lime softening groundwater treatment plants. A potential driver ultimately requiring lime softened groundwater or the use of surface water is a chloride discharge limit in wastewater. A finding in the report as it relates to surface water treatment in the vicinity of Ramsey was that "The Mississippi River has sufficient water quantity to serve the Northwest Metro communities. The water quality in the Mississippi River appears to be acceptable for a conventional surface water treatment plant. St. Could, St. Paul, and Minneapolis utilize the Mississippi River as their source of drinking water." The capital cost of a surface water treatment plant is significantly higher than an iron and manganese groundwater treatment plant. Based on costs presented in the report, the project cost for a 10 MGD surface water treatment plant would be $50 million or more. In addition, the Operation and Maintenance costs of treating surface water is approximately twice as high as iron and manganese treatment. It should be noted that a surface water treatment plant could provide softened water to the residents of Ramsey; whereas an iron and manganese treatment plant would not provide softened water. However, residents that are concerned about hard water are likely already softening their water with a home softener. As of the preparation of this report, the Study was still in draft form. When the Study is complete, it will be available to the public on the MCES website. The citation for the report is: Metropolitan Council. 2020. Northwest Metro Area Regional Water Supply System Study. Prepared by Short Elliott Hendrickson Inc. Metropolitan Council: Saint Paul. Because it has been demonstrated that Ramsey should have sufficient groundwater available to meet future demands, a surface water treatment plant is not recommended at this time. A potential Ramsey groundwater treatment plant will be located close enough to the Mississippi River that it could be converted to a surface water treatment plant in the future if it became necessary. It is recommended that surface water features be designed into a potential water treatment plant. The additional cost of the surface water features is approximately $250,000. Water Treatment To remove manganese, iron, or hardness from Ramsey's drinking water, a centralized water treatment plant should be constructed. Adding the necessary processes to treat the water supply at each pump house would not be cost-effective. FEASIBILITY STUDY RAMSY 154354 Page 26