#09 - Approve Water Supply Study Recommnedations

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STAFF REPORT DATE: February 20, 2024 REGULAR AGENDA ITEM: Approve Water System Study Findings, Recommendations and Next Steps SUBMITTED BY: Jack Griffin, City Engineer REVIEWED BY: Clark Schoeder, Interim City Administrator Marty Powers, Public Works Director Chad Isakson, Assistant City Engineer BACKGROUND: The city council held a workshop on water supply strategies on June 13, 2023 and directed staff to proceed with the necessary engineering evaluations for a revised Water Supply Infrastructure Plan. A revised plan is deemed necessary due to the inability to construct future wells within the White Bear Lake 5-mile radius. Staff worked closely with the MPCA to secure grant funding for the studies and the following studies were authorized by council. 1. September 5, 2023. Authorized engineering services to evaluate treatment for PFAS at Well 2, including options for temporary treatment versus more permanent infrastructure solutions. 2. September 5, 2023. Authorized engineering services to perform water distribution system modeling to determine performance and potential system changes needed with Lake Elmo accessing new water supply source locations. 3. October 17, 2023. Authorized engineering services for the preparation of a water supply plan to develop South Area Production Wells (Well 6 and 7) with treatment for PFAS. ISSUE BEFORE COUNCIL: Should the City Council approve the preliminary findings and recommendations and direct staff to initiate preliminary and final designs for certain improvements as recommended, and to apply for the applicable 3M Settlement Grant Funds? PROPOSAL DETAILS/ANALYSIS: With Well 2 impacted by PFAS, the City evaluated temporary and permanent treatment solutions to produce compliant potable water and maintain Well 2 production capacities until alternative water supply sources can be made available. A summary of the findings and recommendations are as follows: • Well 2 production capacities are needed to meet peak summer demands. Operate Well 2 on emergency basis only through peak 2024 summer demands. Initiate Well 2 rehabilitation and pump replacement in the Fall 2024. • Temporary Anion Exchange (IX) treatment for PFAS at Well 2 is feasible. However, it is unlikely that the proposed system will be available to meet peak demands in 2024. • A prefabricated trailer mounted 500 gpm GAC filter treatment system is not available for use in 2024. • Permanent Anion Exchange (IX) treatment for PFAS at Well 2 is dependent upon further evaluation and MDH approval for long-term use of a pressure cartridge filter for iron and manganese (Fe/Mn) pretreatment. Treatment for PFAS at Well 2 using granular activated carbon (GAC) filter media is not feasible. • Proceed with design phase engineering for an Anion Exchange (IX) Treatment at Well 2 using paired 8-ft high Streel Pressure Vessels. • Secure a Grant Agreement Amendment to fund design phase engineering services. • Obtain sampling and detailed testing of Well 2 for design purposes. • Prepare direct procurement package and order treatment system equipment for accelerated delivery.