This is a carousel. Use Next and Previous buttons to navigate

The city of Manistee is currently rehabilitating problematic manhole covers and sanitary sewer lines. Some of that work entails lining pipes which protects the wastewater treatment plant from added influxes of groundwater while also adding decades to the lines' lifespan. (File photo)

Most streets in Manistee in 1932 featured interceptor sewer discharge points that directly went either to the Manistee River channel or Manistee Lake.  However, currently, the city uses a different system and it also has plans to rehabilitate problematic manhole covers and sanitary sewer lines. (Courtesy image)

EDITOR’S NOTE: This is the second in a three-part series on wastewater treatment in the city of Manistee. Part two focuses on how the processes and challenges have changed over the years for the city’s wastewater system.

MANISTEE — The state of wastewater treatment in the city of Manistee has seen some changes over the last 140 years.

According to the city, the original system was constructed in the 1880s “and consisted of open ditches that transported stormwater mixed with sanitary wastewater from homes and businesses directly into the Manistee River and Manistee Lake.”

Later, ditches were replaced with pipes but the wastewater mix was discharged into the lake and river in untreated form.

The pipes combined both stormwater and wastewater through the same pipe systems and are called combined sewer.

“During wet weather events, the combined sewer overflow structures were designed to overflow excess combined sewer flow into the Manistee River or Manistee Lake to keep from overwhelming the wastewater treatment plant and interceptor sewer,” reads a recent pamphlet created to update customers on ongoing sewer projects.

Jeff Mikula, Manistee Department of Public Works director, said that for various reasons, the city has typically changed the sewer system every 40 years.

“When the original system was built at the turn of the century, it was built as a combined sewer,” he said.

Mikula said at that time, the process was considered state of the art because there was no cesspool in the backyards or dumping into the ravines.

“Anything that was liquid or sewage was tied right into the sanitary pipe, was perfectly legal. So, people had rain gutters around the roofs of their house, those were typically tied into the sewer system; if they had a wet spot in their yard and wanted to pipe it to the sewer system, that was fine and it was legal.”

He said in the 1970s and early '80s, the city wanted to have separation between wastewater and stormwater.

“They started separating the sewers with the construction of new storm sewer so that the pipes from the street, the catch basin, flowed straight to the river and the lake as opposed to through the treatment plant,” he said. “That work continued through 2013.”

Then, he said all the drainage from the streets was completely disconnected making it what is called a separated system.

He said the city turned its attention to looking into sources of inflow that can further overwhelm the plant and increase overflow discharges of untreated wastewater into the lake.

“Following that (separation), the city and its engineers did studies to find out where yards drained, roofs drained, flat roofs, rain gutters, were tied in,” Mikula said adding that the city did three rounds of those studies. “We’ve got all of those that we know of have been disconnected.”

That inflow is now documented and accounted for, leaving infiltration from things like leaky pipes that allow groundwater to infiltrate the system which also contribute to overwhelming the treatment plant.

Mikula said about eight years ago, the city installed transducers in the plant’s final overflow area.

“The storm sewer side of that diversion chamber has a transducer and we also have one on the sanitary side,” he said. “So, we’ve been tracking lake levels, sewage flows, tracking precipitation and our engineers have been studying the correlation between all of those for quite some time.”

He said the conclusion is that most of the non-sewage entering the sewer system is probably coming from homes in the area.

“When those homes were built it was customary to put drains around the foundation and it appears that most of the flow we’ve got now (is) coming from those private sources,” he said. “A lot of the pipes were laid in the late 1800s, early 1900s. We’ve got a lot of pipes that have cracks in them … or leaky joints where those are underneath the water table. Then they also allow water to come into the system.”

He said the plant has been able to quantify how much comes into the plant on a daily basis from groundwater through the leaky pipes. Mikula said they are also able to pinpoint how much wastewater is entering the system during rain storm and snowmelt events.

Recently, there have also been changes to Manistee’s water tables and weather patterns, both of which add pressure to the current system.

Part one: How does it work?

Part three: Manistee city sewer projects in progress: What can customers expect in the end

MAP: This is where Manistee tests for E. coli after sanitary sewer overflow event

Manistee sewer agreement will lower certain costs

Council approves nearly $5M sewer revenue bond

City approves phase two loan application for sewer project