During the mid 1950’s, Plainwell constructed a wastewater treatment plant with a trickling filter as the secondary treatment. Prior to this, raw sewage was discharged to the Kalamazoo River. During the 1970’s, the area was growing and regulatory constraints were becoming an issue at the plant.
With help of an EPA grant it was time to expand the treatment plant. The project cost $3 million and was completed in the early 1980’s.
The improvements gave the plant a 1.3 million gallon per day capacity. Our current flow is 500,000 gallons per day. The new improvements included installation of two new 30′ screw pumps, conversion of the old primary & secondary tanks to just primary clarifiers, removal of the undersized trickling filter from service, and installation of new Rotating Biological Contractors (RBCs). A new sludge heat exchanger, a new secondary pump room, two new final clarifiers, and a new chlorine contact chamber were also added. As expanded, the Superintendent in charge of the new plant was required to have a class B State of Michigan wastewater treatment license.
In 1992, the City built a 500,000 gallon tank for additional bio solids storage.
In 1998, the City invested $500,000 to renovate some of the equipment from the 1980 project. This included improved primary clarifier flow distribution, new primary clarifier hardware, and a new “channel monster” for preliminary treatment. Major renovations to the digester building piping, and a new chopper pump for improved digester mixing. Two new secondary clarifier pumps and piping, and a new raw sludge pump and piping.
In 2002, the City built a second 500,000 biosolids holding tank. The construction cost for the pored wall tank was $780,000. The tank was designed to accommodate future walls that would be poured vertically to increase future storage needs.
In 2003, the City was awarded first place in the EPA’s “Award of Excellence.” The award is chosen from the five states which make up the region and is headquartered in Chicago. The Region 5 EPA award is for outstanding operation and maintenance of a medium secondary treatment facility.
In 2005, the City completed a $1.7 million expansion for bio-solids digestion and methane gas storage. The methane gas holding dome called “Dystor” cost $250,000 to install and enables the City to use and store 30% more gas than conventional tanks. The “Green Project” result of this technology allows the City to heat eight buildings with hot water including the Department of Public Works. The annual natural gas savings from the project each year is $18,000.