Elkhorn sending more water than it should for treatment
Engineering consulting firm Bonestroo developed the report that says the city sends an average 900 gallons per minute to the Walworth County Metropolitan Sewerage District for treatment. Of that, about 400 gallons are rain and ground water that get into the sewers through broken and cracked pipes.
The infiltration is about 44 percent of the total 473 million gallons treated each year and amounts to about 208.1 million gallons of clear water unnecessarily treated each year.
“If we can concentrate efforts to eliminate that, that’ll help us reduce the amount of water we have to pump into WalCoMet, and in turn, that would reduce costs to ratepayers,” said Tom Nennig, an engineer with Bonestroo and project manager of the Elkhorn report.
Elkhorn Administrator Sam Tapson said city officials will work with Bonestroo to collect and analyze data to develop a solution.
“We don’t have all of the information yet to take definitive action,” Tapson said. “You’re not going to pull the trigger on budgeting without knowing some more things.”
Bonestroo’s initial cost estimate to address the infiltration runs about $574,000 over five years
The estimate doesn’t include engineering and other costs, Tapson said, and the final price likely would be higher.
Elkhorn now pays about $1.4 million to WalCoMet each year, Tapson said. The city charges each payer about $1.49 per 100 cubic feet of water—about 748 gallons. About $414,000 in citywide excessive charges could be avoided if the sewer system was fixed.
The report was developed by dividing the Elkhorn sanitary sewer system into five sub-basins to monitor water flow. Engineers studied water flow in April, May and June 2009 to determine dry and wet weather flow patterns.
Basins one, two and three—downtown and north parts of the city—were found to have the highest potential infiltration. Basin five, the southernmost part of the city, had the lowest recorded flow for any of the basins.