Renovation of a water / sewer project in Mankato, Minnesota. Conceptual plans call for the renovation of a water / sewer project.

Replacement of 640 membrane modules. The facility has 8 membranes filter skids consisting of 80 modules each making a total of 640 filter modules total in the facility. 320 modules were replaced in 2017 and 320 in 2018. I would like to begin replacement in 2027 by completing a 50% replacement the middle of the year. This will begin to spread out future module replacements. The membranes cannot be stored on site. They must be put into service when purchased since there is no guaranteed shelf life if they are not actually on-line receiving water. As the filter modules age the small internal strands become brittle and break. Detection is through declining Log Removal Values (LRV), increase Membrane Integrity Testing (MIT)-water flow testing, and the use of sounding gear. The WTP maintenance department is spending one full day every month to maintain an acceptable LRV. The MN Department of Health requires an LRV of 4.0 for potable water. The WTP has set a standard of removing a filter from service for repair if an LRV falls below 4.30. We feel that this proactive approach will keep our team ahead of any arising issues. It will also allow us the time to attend to other emergency repairs before completing membrane repairs. Due to the regulations, extended lead time and increasing maintenance costs it is critical that these be replaced in a timely manner. *The LRV is a number that is calculated by using the last known filtration volume, last known pressure/trans membrane pressure, and the displaced flow on the Membrane Integrity Panel. This test is done daily to record any perforations in the membrane surface where contaminants would have the possibility to pass. *Membrane pinning is a process where the leaks are isolated to the A or B side of the filter. Maintenance will conduct a MIT Diagnostic on the filter in question. At this time they will use an electronic stethoscope to listen for fiber breakage. All vessels with possible leaks are recorded. The filter is then drained and locked out. The modules are pulled and submerged in a water bath, the filtrate side of the fiber is pressurized with air. If there is a leak, air bubbles will expose themselves from one of the 10,000 fibers on the module surface. As of May 21, 2025, The project is include in the City's 2025-2029 Capital Improvement Program (CIP) *Project information has been obtained through a public capital improvement plan (CIP). A CIP is a financial schedule for short- and long-range projects which is updated regularly. Information listed in the CIP often evolves based on funding availability and the project details, including timeline and value, are subject to change. The content management team will continue to pursue additional details as they become available.