Mike Gurr, the city’s utilities field services superintendent, said it may take time to know exactly how effective the ongoing steps have been in keeping rain from entering Hamilton’s sanitary sewers — the kind that are intended to convey waste from toilets, sinks and factories.
But judging from heavy rainfall on April 29 and this past week, far fewer properties had basement flooding, and those who did were scattered across the city, Gurr and Public Works Director Rich Engle said.
Credit: Greg Lynch
Credit: Greg Lynch
Gurr said as of late Thursday afternoon, only one basement that was flooded this week was caused by sewage. The rest had happened because of ponding water near the buildings.
And in April, “We sustained roughly 3 inches of rain, which is a significant amount of water coming into the area in a relatively short period of time,” Gurr said. “And we did not receive any calls at the city for sanitary backups, with any of our customers.”
On the other hand, last week, “Two Mile Creek overflowed and it caused Main Street to shut down,” Gurr added. “And so I believe with that, Two Mile Creek did cause some challenges with some of the residential customers, but that had nothing to do with sanitary (sewage).
“So that illustrates the amount of water that was in the area from rainfall, and with that being said, I’m happy to report that we did not receive any calls for sanitary backups,” Gurr said.
In understanding Hamilton’s flooding situation, it’s important to know the flooding of streets — which was more prevalent last week than last year, and more scattered across Hamilton — is caused by issues with the city’s storm-sewer system, which is intended to carry rain to streams and rivers. Last June and during other storms, the flooding of Main Street, Ross Avenue and other roadways was caused by that, at the same time basements were caused by the sewage system.
Here are approaches Hamilton continues to take to keep sewage from basements:
‘Smoke-and-dye testing’
Crews already have “smoke-and-dye tested” about 4,400 homes so far, with plans to eventually conduct such testing citywide.
They started in the areas of Highland Park and Ross Avenue, both on the West Side, because flooding in 2016 hit those areas hardest. Forcing high-pressure mist through the sewage system, crews can see when homes’ gutters and downspouts are improperly connected to the “sanitary sewers” with their sewage.” Of the 4,400 tested so far, about 90 properties had improper connections to sanitary sewers, sending huge amounts of rain into pipes that weren’t intended for such quantities, Gurr said. Property owners, many using plumbers, are disconnecting the improper links, many with financial help from the city.
Peeking inside pipes
The city has been running video monitors inside its sewer mains to see where they are cracked or have improper connections, and then repairing the faulty areas, either by re-installing sections of pipe, or installing resin-like linings that extend the lives of the pipes and seal the storm water away from the sewage on its way to being treated.
Sealing manhole covers
The city also is taking steps to seal manhole covers near the Great Miami River and Two Mile Creek. A traditional manhole cover has four one-inch holes for ventilation. But in areas where the covers are underwater, crews are using rubber “inflow dishes” inside manhole covers and has taken other steps to keep rain water out. That’s because those four holes, when under water, can allow 44 gallons per minute into the sewage system. Those extra gallons can cause sewage to back up.
Flow monitors inside sewage pipes
Last year, crews lined 10.3 miles of sewage mains, with three more miles planned this year. Workers last year replaced 1,200 feet of 8-inch mains; and just under 1,000 feet of 6-inch; and 60 feet of 18 inch sanitary-sewer replacements. Nearly another 2,100 feet of work on 8-inch mains are planned for this year.
In another key advancement, the city has installed 11 flow monitors in its sewage pipes, which record how much sewage is in a pipe, how fast it’s moving and other data, in five-minute intervals. Consultants are building a computerized model of the city’s sewage system so the data can be used to evaluate areas that are carrying too much liquid, as a way to determine pipes that need to be replaced with larger ones, or situations where too much rain is entering the system during storms. Each of the monitors costs between $3,000 and $4,000. More may be added after the computerized model is created and officials see how many more are needed.
Check valves installed
As a final defense against sewage backups, about 100 homes have had check valves installed, or soon will have them put in. Those one-way valves allow water to drain away from basement drains, but keep sewage from backing up into buildings.
Carolyn Smith, a longtime Highland Park resident who pleaded after the June flooding for city leaders to solve the longtime problem attended a council meeting in March and thanked officials for their help.
“I came here a year ago, frustrated and disillusioned with city government,” Smith said. “For years, the same problems were never solved, or even given the attention needed to identify and correct the issues. You listened, assured me that answers would come, but it would take time.”
“I had a glimmer of hope, but honestly, I thought I was at the bottom of the list,” she added. “But you were true to your word. Not only did you extensively work to identify the problems, you provided homeowners with a program to correct those problems. So thank you so much.”
“In my eyes, you’re good people,” she added, thanking city leaders “for your commitment to this community, its residents, and to problem-solving.”
Gurr said crews eventually will make their way all across Hamilton.
“If we haven’t made it to their location, just be patient. We’re working through. It’s a time-consuming process,” he said. “We’re going door-to-door, essentially, to each one of these homes or businesses to go through the various sanitary sub-basins. It just takes time, and we will continue to make this right as we go forward.”
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