By Kevin Bunch, IJC
When it comes to drinking water, new technologies often mean more data. Water managers at treatment plants, such as one serving Grand Rapids, Michigan, can use data to more accurately prepare and treat drinking water coming into the system and handle sewer overflows.
Communities throughout the Great Lakes region rely on water treatment plants to deliver safely treated water to homes and businesses. Knowing how to treat water on a day-to-day basis has been made easier using new monitoring and computer modeling technologies, said Mike Grenier, superintendent at the Lake Michigan Filtration Plant, which pulls water from the lake about a mile out from shore.
In Grand Rapids, this involves using online monitoring stations throughout the water system, as well as grabbing water samples to test in labs. This data is pulled from the Grand River, pipes in the distribution system and Lake Michigan. Different substances have different testing requirements and time periods.
That monitoring data is used to determine, using computer models, how to adjust the coagulant used to treat the water, depending on contaminant levels, weather conditions and specific water chemistry. These models project what chemical levels and water conditions should be expected when setting up the specific water treatments. Grenier said that if water managers are off on their contaminant expectations, the treatment could prove insufficient to make the water safe to drink.
Additionally, Grenier said water managers sample for other chemicals of interest, such as PFAS compounds – which he noted are safely low at this time based on testing.
Water managers discuss treatment options for new contaminants periodically in the event they discover a potentially dangerous spike. This includes sharing information with other treatment plant superintendents throughout the Great Lakes basin, as well as researchers trying to build a long-term picture of water quality in the Great Lakes.
“Once a month we meet up with superintendents (of other water treatment plants) to see what each other is doing in the Great Lakes,” he said. “We’re always looking out for what’s next.”
Contaminants aren’t the only aspect that water managers consider. Long-term trends suggest that water coming from Lake Michigan has been becoming more acidic, Grenier said. It’s nothing that has affected the treatment work at this time, he added, as the shifts have been fairly minor so far.
“At some point in time we’ll need to switch coagulants,” Grenier said. He added that they’ve also seen an increase in chloride in the water, which translates to the lake becoming saltier.
Water quality beyond the treatment plant
Grand Rapids has been instituting other measures to optimize its water infrastructure and improve water quality. In 1969, the city had 47.6 million kiloliters (12.6 billion) gallons of raw untreated sewage enter the Grand River, according to a presentation prepared by Grand Rapids Environmental Assessment Supervisor Nicole Pasch for the 2018 International Association for Great Lakes Research Conference in Toronto.
To reduce overall runoff and pollution, Pasch said Grand Rapids was using a “water resource recovery facility” to treat wastewater, including from industrial sources, and reuse it within the water system – and treating around 151,416 kiloliters (40 million gallons) and recovering an estimated 1,362 kiloliters (360,000 gallons) of water each day.
As of June 2018, Pasch noted there were no reported combined sewer overflows (caused by combined stormwater and wastewater sewer lines overflowing during precipitation or snowmelt events), with 59 specific points where stormwater would flow untreated into the stream eliminated. She added the city had been separating its stormwater and wastewater sewer lines to reduce the chance of contaminated overflows, completing that project in 2015.
Aside from the existing stormwater model, Pasch said a water quality computer model for the Grand River is in development. Once completed, the city’s utilities can keep track of contaminants of concern, such as sediment or E. coli bacteria, said Michael Lunn, environmental services manager for Grand Rapids. This is especially important after the city sees a rain event.
“The stormwater intercepts that river almost directly, whereas wastewater only touches it downstream after it comes out of the treatment plant,” Lunn said.
Grand Rapids has been working with outside organizations to restore the Grand River and reduce stormwater runoff using rain gardens as ways to keep runoff and pollutants out of the water system. Pasch said they’ve been looking at opportunities upstream and downstream to improve the watershed’s health, including habitat restoration along the waterfront and runoff reduction opportunities using green infrastructure.
Looking ahead, Pasch and Lunn said Grand Rapids has been open about sharing data and practices with other communities and organizations, from water quality to air quality.
“I think we’re all trying to find our way in this,” Lunn said.