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Flowmeters help Allen County, Ohio, solve I&I problem
A long-range inflow and infiltration (I&I) plan is currently underway in Allen County, Ohio. The Wastewater Treatment Division operates three major treatment plants located in Bath, Shawnee and American Townships and three smaller package treatment plants located in Bath and Richland Townships. The Wastewater Collection Maintenance Division is responsible for the maintenance and operation of approximately 170 miles of sewer lines and 46 sewage lift stations located within American, Bath and Shawnee Townships.
Bill Horvath, superintendent for the Allen County Wastewater Collection Division, said "Like the rest of the country, we have some old leaky sewers that are the source of some of our I&I problems. We are under an order from the Ohio Environmental Protection Agency to close six sewer system overflows (SSOs) within the next 10 years. The SSOs flow into the Ottawa River that feeds Lake Erie."
As part of the initiative to identify and isolate I&I, Allen County has relined approximately 22,000 ft of sewer line over the last two years with plans to complete an additional 20,000 ft in 2006. A large number of flowmeters would also be required to accomplish the many monitoring tasks involved in their long range I&I program.
A new generation
Intrigued with the concept of a maintenance-free, non-contact flow sensor from Marsh-McBirney that allows personnel to simply "drive-up" to the site for flowmeter downloads, Allen County investigated further. The Flo-Dar family of products represents a new generation of flowmeters that provide a revolutionary approach to open channel and sewer flow monitoring. Flo-Dar combines digital doppler radar velocity sensing technology with ultrasonic pulse echo level sensing to remotely measure open channel flows.
A final decision was made in the summer of 2004 to purchase 22 portable Flo-Dar flowmeter systems, each composed of a Flo-Dar sensor with an optional surcharge velocity sensor as well as a portable Flo-Logger. In addition, six Flo-Tote 3 meters were purchased as part of a trade-in program for the county’s older Tote II meters.
Marsh-McBirney's Mobile Radio Frequency (RF) option was also purchased for the meters. This option would reduce confined space entry during site visits for data downloads, as well as keep flow monitoring personnel safe and out of the sewer as much as possible. The feature reduces routine data collection costs with the use of a "drive-up" data collection feature and quickly pays for itself in labor savings alone, not to mention the convenience and safety features mobile data collection offers. With Mobile RF, there is no need to remove the manhole cover because operation and data can be uploaded up to 100 ft from the monitoring site.
Saving time & money
"We've done a lot of work trying to isolate the I&I problem areas and to strategically stage the meters to get the most accurate flow data," Horath said. "We are also using the meters in areas where we have done some relining. We are doing some pre- and post-type monitoring to get an idea of how much impact the relining has had. The Flo-Tote 3s are permanently monitoring flow in the SSOs."
With the reduction of confined space entry at flow site visits and "drive-up" data uploads, Horvath noted they are saving money on manpower.
He added, "We really like the RF option because it saves us time and it’s working out real good. I'm not sure of the exact dollar amount we are saving but let me put it this way—we are doing it with one man [Wastewater Collection Operator II Dave Shrider] taking care of all of these. It is just incredible."