R. R. Branstrom | Daily Press A newly-constructed primary clarifier at Gladstone’s wastewater treatment plant will be put to use soon.

GLADSTONE — A large-scale project to overhaul Gladstone’s Wastewater Treatment Plant — an endeavor of roughly $20 million, loaned to the city by the state — has been underway while the existing facilities, built in 1974, continue regular operations. Engineering firm C2AE designed the plans, and Staab Construction Corporation is on the job. Physical work began in June of 2022 and is expected to wrap up this summer.

The plant at 413 Minneapolis Ave. takes in about 400,000 gallons of wastewater — from households and industries in City of Gladstone and Masonville Township — each day, estimated Gladstone Wastewater Superintendent Rodney Schwartz.

The rebuild intends to increase the capacity, add some newer technology, and in general set the plant up for better operation.

After first going through a coarse screen, which catches large objects like rags, wastewater is currently pumped up to a horizontal grit chamber, where flow slows and allows heavier inorganic material to settle.

In the new system, water will go through a rotary drum screen and a vortex grit removal system, which, according to EPA, removes a high percentage of fine grit and has “a consistent removal efficiency over a wide flow range.”

After grit is removed, wastewater goes into a primary clarifier where aluminum sulfate (“alum”) acts as a coagulant that helps organic waste bind together and sink to the bottom, where it’s pushed into a hopper and into a digester. The same bars, called flights, that scrape settlement into the hopper ride on chains along a cyclical track that also takes them up and along the surface of the water to scrape away the floating “FOG” (fats, oils and grease).

The wastewater treatment plant in Gladstone has been operating with one primary clarifier but will have two running soon.

“We’re adding another one because before, whenever we had an issue and we had to take that primary clarifier down… I’d have to call up EGLE (Michigan Department of Environment, Great Lakes and Energy) and let them know what we’re doing and why,” Schwartz explained, adding that in such a case, it might be eight or 10 hours that the clarifying part of treatment was bypassed, resulting in water that was not fully treated — but still completely compliant — leaving the plant. Having two primary clarifiers will give the option to divert the flow to one if the other needs servicing, leaving no step bypassed.

The plant has a new dual-fueled gas boiler, which can be fueled by methane created in a digester or by natural gas when there’s not enough methane. This boiler’s purpose is to create heat in the primary digester to break down sludge, which has previously been done just by running hot water through pipes.

The next area to get an upgrade is the biofilm process. The Gladstone plant’s new moving bed biofilm reactor (MBBR) replaces the old biodisc system. Both are aerated systems that employ microorganisms to break down pollutants.

After plans for the whole improvement project were first created by C2AE, they were approved by the City Commission, then gained approval from the State Revolving Fund (SRF) with 15% principal forgiveness.

The winning bid by Staab Construction was $17,433,000. Adding that to other costs — such as for engineering, plus a $1.2 million contingency built in in case costs rise — the estimated project total came to $21,306,908. Gladstone will be on the hook for 85% of that because of the SRF forgiveness. The anticipated interest rate is 2.125%, and the City expects to pay back the state in 30 years.

Currently, monthly requests for funds come before the Gladstone City Commission, then head to EGLE for approval before the State writes a check.

When all is said and done, some parts of the plant will have new purpose. They already have a new laboratory, where water is tested five days a week from three different stages of treatment.

“We’ll test the influent — what’s coming in — what’s coming out of the primary effluent tanks (clarifiers), and then what’s going out to the lake,” said Schwartz.

The plant will be doing the same job as it always has — just modernized and upsized.