Grosse Pointe News | January 18th, 2018 | Grosse Pointe News - Jan. 18, 2018 - News section, 1A
Water Plant’s ‘Wheeler Bottom’ passing inspection By Melissa Walsh
Grosse Pointe Farms — The water filtration plant at Kerby and Moross brings Farms and City residents the priceless gift of clean water each day.
As part of his role in ensuring water quality, Farms Water Superintendent Scott Homminga is overseeing the inspection of the plant’s underdrain system, which hasn’t been viewed since 1995. The system is known as the “Wheeler Bottom” of the station’s eight filters.
“Of all of the plants I’ve ever worked at, I’ve never seen the bottoms,” Homminga said.
Since earning a degree in water purification from Bay College in Escanaba in 1990, Homminga has worked in water filtration and treatment in Wyandotte, Ann Arbor, Howell and Marine City. He started in the Farms in 2003.
The facility built in 1929, Homminga said “has really provided the community with great water ever since. This plant is run more gently. It’s not pushed to the limit.”
The Farms Water Treatment Plant is rated for handling 10 million gallons of water per day; but the average is five, he said, with low backwash rates.
“When we backwash to clear the filters and water backs up,” Homminga explained, “the ceramic cells disperse the water evenly.”
This underdrain’s ceramic material layer, or “Wheeler Bottom,” is being inspected by a representative of F.B. Leopold Co., manufacturer of the material. The layer consists of 10 inch x 10 inch cones fitted with inverted pyramids, each containing 3-inch ceramic spheres, supported by a 1-inch ball.
A 14-inch layer of graded gravel is placed on top of the ceramic material to support the filtration media and distribute backwash water. Another 14-inch layer of granular activated carbon, or GAC, lies on top of that.
Preparing the filters for inspection, Homminga is overseeing the removal of 40 tons of this filtration material. Four of the eight filters have undergone the removal of the filtration material, and their underdrain ceramic material layer has passed inspection, he said, requiring only minor regrouting work.
GAC, which is like a sponge soaking up and removing organics from the water, Homminga explained, is replaced every five years. Other communities, such as those depending on inland river water, may need to replace GAC as frequently as twice a year. The communities depending on Lake St. Clair water, he said, are lucky.
“Fortunately, Lake St. Clair has been a very good source for water,” Homminga said. “Lake St. Clair replenishes itself every day. The water moves in and out all the time.”
Homminga’s staff runs turbidity tests of the lake water hourly, measuring inorganic and organic matter. He said the water is consistently below the .3 EPA standard.
“I haven’t had an issue with the source water. But I can’t speak to future regulations,” Homminga said.
Currently, he said, “It’s an extremely regulated process.”
The process begins with pumping water into the plant from Lake St. Clair. Next, the water is chlorinated and a sedimentation coagulation process is applied using a polyaluminum chloride solution whereby smaller sediment particles form into larger particles to settle for removal. The water enters the station’s eight large filter basins, where GAC cleanses the water of organics, including chlorine. An ultra-violet disinfectant is applied before the water is re-chlorinated per end-of-distribution regulations. Last, the water is cleared from the well at the rate of at least 2 1/2 gallons per day to enter the water distribution systems in the Farms and City.