COLUMBIA — When heavy rain falls in Columbia, sewage sometimes bubbles up from manholes or into private homes and businesses in older parts of the city.
The city hopes to solve that problem under a proposed agreement with the Missouri Department of Natural Resources that calls for upgrades to and maintenance of wastewater collection systems.
Steven Hunt, a civil engineer for the city's Public Works Department, presented the agreement to the City Council before its regular meeting Monday night. Hunt said work has already begun on several sanitary sewer basins in.
Sanitary sewer overflows are instances when untreated sewage erupts from storm basins during heavy rainfall. They often result from poorly maintained equipment and sewers, according the the Environmental Protection Agency's website. They are illegal because they harm the environment and threaten human health.
The city wastewater collection system was found to be in violation of the Missouri Clean Water Law for failing to maintain facilities and allowing water contaminants to pollute state water, according to the agreement.
An investigation last summer by the EPA found that Columbia experienced 409 sanitary sewer overflows over the past 10 years; 168 of those were backups into buildings and private properties.
The city will have to spend an estimated $56.9 million to repair its sewers and stop these overflows, based on the agreement with the natural resources department.
The city plans to finance the repairs with the proceeds of three bond issues. It would use $3 million of a $77 million bond issue that voters approved in 2008. It also plans to take a $29.8 million bond issue to voters in 2012 and a $24.2 million bond issue in 2017. If voters approve those, the average monthly residential sewer bill by 2017 would be $31.20, up $10.82 cents from the current average bill of $20.38.
The problem with sanitary sewer overflows has gone on for years. Thirty-one occurred between 1976 and 2007. Three large storms in 2008, 2009 and 2010 increased the number of overflows dramatically; 185 happened in those three years.
Mayor Bob McDavid asked Hunt at the work session whether the system is inherently flawed or whether excess rain during those years caused the problems.
"I guess somewhere in between," Hunt answered. He said that cracked pipes and clay blockages have become increasingly challenging problems as the system ages.
Ken Midkiff, conservation chair of the Osage Group of the Sierra Club, brought the problem to the state's attention in February when he said he saw raw sewage along the MKT Nature and Fitness Trail. The issue, he said, arises when older cities ignore the need to update sewer equipment.
"It would have been much cheaper if this had been done a long time ago," Midkiff said before the work session.
Council members now have to decide whether to sign the agreement with the natural resources department, which carries several benchmark requirements.
Within 180 days of signing, the city would have to create a system to track and manage information regarding sanitary sewer overflows that would allow easy analysis and computer access for city employees.
The city also would be required to create a work plan that would reduce the overflows over time. Hunt said that a completed survey of all basins gave each one a priority rating based on amount of inflow, sewer overflow and basement backups.
The plan requires the city to complete work on the top 25 basins by 2026. That is estimated to reduce inflow and infiltration, water that causes damage to pipes and equipment, by 80 percent. Hunt projected the work could be completed four years early.
If city officials do not comply with these stipulations, the natural resources department will sue. Late compliance will result in increasing fines of up to $2,500 per day.
Midkiff hopes the agreement and potential consequences set down by the natural resources department will cause the city to act.
"Nobody wants raw sewage running in places where it shouldn't go," he said.