Due to high levels of ammonia in Hillsdale’s water for the past two years, the city of Hillsdale will spend approximately $6.9 million to upgrade deteriorating equipment and install new, energy efficient equipment at the Hillsdale Wastewater Treatment Plant. Since the final engineering and construction costs are not yet determined, there is no date for beginning the plant’s improvements.
“We will be borrowing money from the state of Michigan Revolving Fund; it will be a revenue bond,” acting City Manager Doug Terry said. “We will borrow through a revenue bond and pay it back through water and sewer fees.”
Some of the plant’s infrastructure is 67 years old, and the technology was last updated in 1992, Terry said.
“Sewage treatment has been around for a long time, but there has been some new technology introduced as well as new regulation,” Terry said.
Currently, the plant uses sand filtration to strain impurities out of the water. Part of the plant’s improvement plan will include a new filtration system that uses disc filtration.
“Disc filtration has microfibers — it’s a fabric filter — which is more effective in filtering,” Terry said.
BPU Director Rick Rose said the high ammonia levels have been a problem for the past two years, and if the city doesn’t fix the problem, it could get a court order from the Michigan Department of Environmental Quality, which would force it to confront the issue.
“We started getting high test results for ammonia about two years ago, and a year ago this last November we had a meeting in Jackson to talk about it,” Rose said. “We agreed we really needed to get something done. Some of the plant is in really bad shape.”
Because the BPU reports to the DEQ monthly, the DEQ knows Hillsdale is working to remedy the situation. Even though the ammonia levels are still high, they are not hazardous.
“As long as they’re aware of it and know we’re working towards fixing it, it’s not a big problem,” Rose said.
Other improvements include installing a generator, replacing three rectangular primary clarifiers with one round primary clarifier, replacing three rectangular secondary clarifiers with one round secondary clarifier, and refurbishing the anaerobic digester, said operator Mike Simons.
In Hillsdale wastewater treatment, untreated water undergoes treatment in the primary clarifiers (which remove solids, oils, and grease from the water) and treatment in the secondary clarifiers (which remove biological matter) before being oxidized, filtered, treated with chlorine, and released into the St. Joe River. The materials filtered out of the water are referred to as “sludge,” the byproduct of wastewater treatment.
Anaerobic digesters — which treat sludge and prepare it for other uses, such as farm fertilizer — emit methane gas, but the refurbished digester at the Hillsdale plant will recapture methane and use it as an energy source to provide some heating and electricity at the plant, Simons said.
“We are very excited to be given an opportunity to upgrade our wastewater treatment facility,” Terry said. “The renovations planned for our existing facility will help ensure environmental compliance for many years.”
