Combined street runoff and storm sewer drains contribute to problem
By SUE SUCHYTA
Sunday Times Newspapers
SOUTHGATE – Basement flooding, a longtime complaint of neighborhoods built in the 1950s, may be helped by backflow preventers, City Manager Dustin Lent said during a July 15 online City Council meeting.
A backflow preventer is a device designed to prevent water from backing up, a one-way check valve that only allows a fluid to flow in one direction.
However, Lent said the main cause of the basement flooding in older neighborhoods is street water runoff that is not separated from sanitary sewers, which overwhelms the system during heavy rain storms, and is the root cause of the problem, which cannot be easily fixed without a major infrastructure overhaul, which would have a price tag of half a billion dollars.
City Engineer John Hennessey said Southgate’s combined system allows street runoff water to merge with the sewer system, into the same pipes, which are separated in newer neighborhoods.
“What happened on Friday night (July 10) was we got approximately two inches of water in about an hour,” Hennessey said. “The street flooding overwhelms the sanitary sewer system, and the water within the sewer system can be so large that your footing drain water can’t get out.”
He said the energy in the sewer system is greater than the system coming from an individual house.
“It’s like trying to get on to a freeway, where it is completely blocked, and you can’t get on to the on ramp,” Hennessey said. “But we are working with Wayne County to implement a large sewer project to remove some of the street runoff from this region.”
He said backflow preventers can provide immediate relief to help prevent flooding basements. However, the city is mapping the areas in the city where flooding is occurring, and the city government is taking an aggressive approach to infrastructure rehabilitation.
“We have made some great strides, we’ve done millions of dollars in grants, but the problem that we are running into is we have got an older system that really wasn’t designed for these type of rain events that we are getting now,” Hennessey said. “The weather patterns have changed over the past 10 years.”
Hennessey said the infrastructure needs to accommodate the runoff changes.
Lent said that about 60 percent of Southgate’s residential neighborhoods, on the east side of town, have street water runoff combined with the sanitary sewer system. He said the 40 percent of neighborhoods with separated sewer systems are mostly on the west side of Dix-Toledo Road, from Eureka.
Lent said if an individual house has a 40-foot line as opposed to a 20-foot line going to the main, it would have twice the protection before water would back up into a basement, which is why one basement will have water backup while a neighbor will not.
He said when the city got a grant after the 2014 flooding and installed backflow preventers for low income seniors, the move was very successful.
“Unfortunately, it is a combination of us being a combined sanitary sewer system, the aging facility of any home built back in the ’50s, and the change of the weather patterns, and having more torrential downpours than we ever used to,” Lent said.
Lent said many older communities in Michigan and throughout the country face the same infrastructure challenges.
He said some of the aging sewer pipes have been relined, and the city is looking at creating a large relief drain area, which could potentially relieve basement flooding.
Lent said once Wayne County and the state of Michigan approve a relief drain area, it would still take about two years to complete.
Hennessy said there are redundant pumps to support the sanitary sewers as they carry waste water away from the city, and pump stations are supported by generators if electrical power is disrupted by a storm.
Mayor Joseph Kuspa said he remembers, as a child, helping to bail out his family’s basement on Helen Street.
“What a lot of people don’t realize is we use our basements, because of the small footprint of our homes, as livable space,” he said. “They weren’t intended that way when they originally were built, back in the ’40s and ’50s. People did not modernize their basements.”
Kuspa said using basements as livable space has exacerbated the problem.
“We have to try and come up with reasonable solutions to fix this, so that everybody is not in fear every time it rains, that there is going to be backflow into their basements,” he said.
Kuspa said the 2014 flooding set the course for the city to find long-term solutions to prevent future basement flooding.
He said while a large relief drain area will alleviate some problems, backflow preventers are also a crucial part of the long-term solution.
“We all live with an antiquated system, and it would be cost prohibitive to actually produce a separated system,” Kuspa said. “I think it would be half a billion dollars, was the last estimate I heard, to actually separate (the sewers) in those areas that were affected, in the older neighborhoods.”