Water Treatment Plant

The Comfrey Water Treatment Plant was built in 1999 at a cost of $450,000.00. It was paid for through grant money from the State of Minnesota and by user fees.
The Comfrey Water Treatment Plant has a maximum design capacity of 165,000 gallons per day.  It is a Class facility.
The water treatment plant system provides for removal of iron and manganese.  The filter unit is composed of three components:  an aerator, a detention tank; and a four cell sand filter.  The three components are stacked to save space with the total system height at over 25 feet.  The water is pumped from municipal wells No. 1,2 and 3 to the top of the aerator.  New well No. 4 was added in January 2000. The purpose of aerator is to enhance the oxidation of iron and manganese to an insoluble form so that it can be filtered from the water.  The aerator is comprised of numerous PVC slats in which the water is forced to cascade. A forced draft fan blows air through the aerator to further aid in the oxidation process.
From the aerator, the water falls into a detention tank whcih holds the water for approximately 30 minutes.  The detention tank allows for further oxidation of the iron and manganese.  The chemical Potassium Permanganate and Chlorine can be added prior to the detention tank to assist in the oxidation of iron and manganese.
After the detention tank, the water flows into the 4-cell filter area.  Each filter cell has approximately 10 sq.ft. of surface area and consists of an underdrain system, support gravel and filter media.  The underdrain system is comprised of a metal plate with diffusers spaced at 12 inches on center.  Fourteen inches of gravel is placed on top of the underdrain system and provides support for the media.  The filter media itself is composed of 30 inches of anthracite coal.  The anthracite coal filters out the iron and manganese which were oxidized to an insoluble form in the previous stages.
The treated water, which is now ready for distribution, flow into the clearwell which is located below the filter section.  Two high service pumps draw water from the clearwell.  These pumps distribute water to the tower as well as directly into the city water distribution system.  Before leaving the plant, the water is chlorinated to provide a disinfecting residual throughout the system and fluoridated to enhance public dental health.
The material which has been trapped by the filter beds are removed from the filters by a process called backwashing.  Backwashing is accomplished by means of reversing the flow of the water through the filter cells.  This water is discharged to the city sanitary sewer system for treatment.
The facility's main operator is Steven Berberich.