AWWA MTC64548

In order to provide a new source of drinking water to residents of Central Brown County (CBCWA), Wisconsin, the Manitowoc Public Utilities (MPU) developed a project to design and construct a new 25 mgd submerged microfiltration (MF) plant that would draw water from Lake Michigan. The work at the WTP is one component of a joint project between MPU and the CBCWA to cost effectively bring Lake Michigan water to the region. The new MF facilities will be installed within MPU's decommissioned conventional treatment plant, offline since 2000 after the startup of a 12 mgd pressure MF plant. The new submerged MF facility includes space for an ultimate 45 mgd capacity of membrane equipment with pretreatment strainers and chemical cleaning equipment all housed within the space of a 10 mgd conventional filter gallery. The facilities also include a swing cell, which can operate intermittently as a secondary recovery skid, reducing residuals waste to less than 1% of plant flow during periods in which residuals must be discharged to the sewer. Other improvements associated with the joint project include a new 4,000 foot lake intake, 28 MGD raw water pumping station, 3 MG finished water reservoir, 25 MGD finished water pumping station, over 60 miles of transmission main, and over a dozen metering and pressure reducing stations. This paper provides interesting comparisons between the design of the pressure MF plant and the new submerged MF plant. The new submerged membrane system is in the final stages of construction and in the initial stages of startup and testing. Includes figures.