Costly tunnel for sewage? Alternative sought here
Clintonville's old system fills river during heavy rains; EPA looking for creative, less-expensive solutions
Ohio Environmental Protection Agency officials have selected a large swath of Clintonville for a test of innovative approaches toward keeping the Olentangy River clean.
If engineering firms being asked to submit proposals to Columbus' Department of Public Utilities can't find creative ways to halt heavy rainfalls from causing sewer overflows, the alternative is a $2 billion tunnel project.
Under a 2005 consent decree with the Ohio EPA, a tunnel 170 feet deep already is being constructed Downtown to divert storm water runoff from the Scioto River.
Susan Ashbrook, assistant director for sustainability with the Department of Public Utilities, and Dax Blake, administrator of the Division of Sewerage and Drainage, attended last week's Clintonville Area Commission meeting to give the community a "heads-up on a project we're pretty excited about," Ashbrook said.
"No decisions have been made," she said, but added with requests for proposals out to engineering companies, word soon could leak out about Clintonville's status as a possible pilot project.
The problem that needs to be addressed under the city's agreement with the state, Ashbrook said, is the pollution that flows into the Olentangy when heavy rains overwhelm the drainage system in northern and central Clintonville -- an area that covers 1,000 acres and encompasses around 3,000 homes. Minor leaks in sewer pipes that normally aren't an issue allow raw sewage to be discharged into the river during these wet-weather overflows.
The website of Nicholson Construction, one of the companies involved in the tunnel project under construction Downtown, says sewer systems originally built in many cities were designed to carry storm water and raw sewage away from homes and businesses in a single, combined pipe.
Prior to sewage treatment plants, the contents of these combined sewer systems would be transported to the nearest river.
In the 1950s, based on the development of sewage treatment plants, the contents of combined sewer systems were diverted to sewage plants for treatment and sterilization. Overflow pipes were installed in the existing systems in order to better manage higher quantities of sewage and storm water in the pipes, according to the website.
Many cities still use these systems, which function well in dry weather -- but during heavy rains, they are designed to overflow into streams and rivers, rather than back up into homes and businesses, the website says.
The tunnel -- 20 feet in diameter and paralleling the Olentangy River -- is one possible solution, and might still be the one that gets the green light, Ashbrook told CAC members. Construction on the Olentangy Scioto Interceptor Sewer Augmentation Relief Sewer in downtown Columbus began in September 2010, according to the city's website. The cost of the first phase is estimated at $264.5 million.
"This sewer tunnel will intercept wet-weather overflows that currently empty into the Scioto River and carry the flows instead to the city's Jackson Pike and Southerly wastewater treatment plant," the website states.
Rather than duplicate that project, Ashbrook said city officials negotiated with their Ohio EPA counterparts for permission to seek other means of keeping clean water out of the sewer lines. EPA administrators agreed to put the tunnel project on hold until September 2015.
In the meantime, the Department of Public Utilities is asking engineering firms to determine if rain gardens, additional tree lawns and other ideas might work better and at less expense, Ashbrook said.
The hope is that engineering outfits can come up with "ways to mimic nature" in capturing heavy rainfall, she said.
"It's really just in a study phase," Blake said.
Clintonville was selected as the guinea pig because of the age of its sewer system, Ashbrook said.
The sewage overflows that would be captured by the proposed tunnel would be necessary only a handful of times a year, she said.
The tunnel project would stretch out over the next four decades, she said, while the alternative plans being solicited are more likely to occur within the next 30 years.
Blake pointed out the U.S. EPA has "substantial changes pending" in terms of storm-water regulations for cities across the country.
"We're trying to get ahead of the game here," he said.
"This is just the beginning," Ashbrook said.