ThisWeek CW 04/19/2012
One broken manhole cover near U.S. Route 33 allowed more than 700,000 gallons of water to enter the city’s sewer system during a single rainstorm.
“We were lucky to find a significant thing like this,” Public Service Director Matt Peoples told city council’s service committee at its meeting April 16. “Something as small as a 5-gallon leak can cost thousands of dollars over time, and you may struggle to find that.”
Steve Smith, the city’s water reclamation manager, said a severe rainstorm early this year alerted officials to the problem after they realized the city was pumping nearly 3 million gallons of water per day as opposed to the average of 1 million to 2 million gallons.
The infiltration was equivalent to 80 percent of the entire inflow at the Route 33 lift station, he said.
“We were having infiltration from the Route 33 area, but we don’t have meters on the pumps at the (Route 33) lift station, so what we did was, when we started seeing increased flow, we judge it by the pump capacity and how many hours the pumps ran,” Smith said.
According to Smith, employees realized they could not locate all the city sewer system manhole covers during inspections in 2010.
“My plan has always been to inspect 25 percent of the manholes per year so they are inspected on a four-year cycle,” Smith said. “We began searching for these manholes and couldn’t find them starting back in November of 2010.”
Smith said the area they needed to search is a peat bog that had become too full of water and overgrown with vegetation.
Last month, the area was dry enough so city crews could use a smoke test to find the leak, Smith said. This is a process by which a machine creates smoke that fills the empty spaces in sewer plumbing; the smoke rises into the air wherever a leak occurs.
“Last week, we were finally able to get out there. So we ran a smoke test for this and we saw a pile of debris in the middle of the field with smoke billowing out of it. We pulled away some rubble to find a broken manhole,” he said. “We found that gap was letting in 700,000 to 800,000 gallons of water a day.”
The smoke test also revealed a leak in a nearby resident’s basement, Smith said. He said the new pumps were significantly more efficient, so the cost of this leak is not as bad as it could have been.
“I haven’t quantified the cost. If we hadn’t found the problem, we may have ended up with a sanitary sewer overflow, which would have caused us problems with the Ohio EPA,” he said. “Of course, with this inflow water pumped at the lift station as well as the treatment plant, our power costs increase.”
The real win, according to Smith, was that by finding and fixing the problem, residents will not experience flooded basements and other property damage related to the inflow and infiltration issue.