Written by Kelly Kaczala
February 20, 2009
More temporary flow meters are needed in the city’s sanitary sewer system that would help reduce or eliminate excessive storm water, or inflow and infiltration (I&I) from the wastewater collection system.
The city installed temporary flow meters at five locations last September in the sanitary sewer system
Significant rainfall sparked I&I issues last July, when several residents complained about flooded basements.
Flow monitoring, video detection and smoke testing help identify inflow and infiltration sources.
Oregon City Council on Monday will consider approving a $50,880 contract with Jones & Henry Engineers, LTD, to provide continued engineering services and install, operate and monitor temporary flow meters at the current five locations and at an additional six locations for four months.
“This ordinance is needed to continue the flow monitoring work that we’ve done,” Public Service Director Paul Roman said at a committee of the whole meeting last Monday.
Data collected from the meters was included in an interim flow monitoring report, said Roman.
“One of the biggest items that stood out is that there is a lot of I&I throughout the older sections of the city, which I call the Wheeling Street district,” said Roman. “The Wheeling Street district has really turned out to be, I believe, a big source of direct storm inflow into the sanitary sewer. I think this is, in my mind, the primary target, at least within the City of Oregon’s system, to do smoke testing.”
Flow monitoring, said Roman, will do two things: “As you try and monitor smaller areas, you get a better idea which subdivision is worse. It gives you more data to simply find where these sources are coming from. Flow monitoring is also going to tell you about infiltration - storm water that gets into the joints – and which areas are bad. There might be some subdivisions that have worse infiltration than others. You want to know through this data as to where you target your investigation. We do have data that there’s heavy I&I coming from the Northwest Sewer District as well. We need much further discussions with the Northwest Sewer District, especially on their contract, and what they’ve done,” said Roman.
The District has done a lot of I&I reduction already, said Roman.
“But I do question to what degree they’ve done it in the gravity sewer system that comes directly into Oregon. I know they’ve done it in the upstream reaches. I question how much they’ve done it with their larger sewer that comes across Northwood into the city. So there’s a lot of discussion there and it will continue. But Wheeling Street, in my mind, is the target.”
The contract will extend the program until June, he said.
“It would get us a lot of good data. It may be, come June, we extend some of it, or relocate some of the flow monitors to new areas. But I do believe Wheeling Street is our target area. And I do plan to do smoke testing starting in May or June. But the flow monitoring data is valuable to start that work as well,” said Roman.