January 24, 2018 – In the wake of the clean water public health catastrophe in Flint, Michigan, a dozen communities in Flint’s own Genesee County are now receiving drinking water from a new water treatment facility. Supplied by water from Lake Huron via the newly-built, $274-million Karegnondi Water Authority (KWA) pipeline, the $72-million Genesee County Water Treatment Plant is equipped with the latest-generation process technology, including CONTRAFAST® high-rate sludge thickening clarifiers and CenTROL® gravity filters in a cluster arrangement, designed by WesTech Engineering.
With the heightened emphasis on safe, potable water following the highly-publicized concerns over water safety in nearby Flint, Genesee County officials made rigorous efforts to ensure its water meets State and EPA requirements for the communities and residents serviced by the KWA pipeline and the county’s new water treatment plant.
When Genesee County decided to treat its own water, and build a new treatment plant, its choices included conventional treatment, reverse osmosis, and microfiltration. County officials chose a conventional treatment plant because they believed it was the best system to deliver the highest quality water to its residents.
Genesee County Drain Commissioner, Jeff Wright, told the Flint News: “We understand the importance of water safety. Our plant mirrors the first-class treatment process conducted by our previous water supplier, the Great Lake Water Authority, treating the same Lake Huron water.”
Central to the performance of the Genesee County Water Treatment Plant is its high-rate sludge thickening clarifier. As early as 2015, the County began testing the WesTech CONTRAFAST clarifier at one of the City of Saginaw’s reservoirs, which also receives water from Lake Huron.
The CONTRAFAST pilot operated like a miniature water treatment plant, pulling water from one of Saginaw's two 90-million-gallon reservoir cells. A filtration pilot column was included as part of the testing to determine filterability of the CONTRAFAST unit effluent. The process was designed to assess the effectiveness of the entire treatment process which Genesee County planned to use in its new plant, and ultimately did select.
“The clarifier utilizes a combination of internal and external solids recirculation, and tube-settling clarification,” said Jeff Easton, WesTech Process Engineer. “It is capable of running at four times the rate typically used for conventional clarifiers, and produces sludge with as much as 10 percent solids by weight, eliminating the need for a gravity thickener.”
The entire process takes place in a single basin, greatly reducing plant footprint.
Once the CONTRAFAST units have clarified the water, it passes through two CenTROL cluster filters. Each CenTROL unit includes four gravity filter cells arranged around a centrally located influent distributor box and backwash waste control column. An operating platform on top of the distributor box allows convenient visual inspection of four filter cells from this central location.
Inlet weirs within the distributors evenly divide flow between all online filter cells without the use of electro-mechanical flow control systems. Hydraulic flow control through the filter system eliminates potential flow surging, providing a consistent high-quality effluent.
The 94,000-square-foot treatment plant, accessory buildings and retention basins, positioned on 80 acres, put Genesee county at the forefront of water supply safety and innovation.
Shortly after the facility opened, Wright told the Division Index (MI) that the pipeline and treatment facility were constructed on time and under budget. He also said that the facility will save hundreds of millions of dollars over the next 30 years; stabilize water rates; ensure the lowest water rates in the Great Lakes region; and provide a solution that will last 100 years.