LIBERTY TWP., Ohio -- The first thing to be built at Liberty Center won't get much notice by shoppers who converge on the $300 million mega shopping, office and entertainment development targeted to open here in 2015.
It’s an underground detention basin that will be used to irrigate the 65-acre development off I-75 and Ohio State Route 129. The basin will also protect local streams from stormwater runoff, developers said.
“It seems to be a very environmentally friendly approach,” said Butler County Administrator Charlie Young. “You’re putting a lot of different new and cutting edge kind of thoughts into play with the pervious pavers, the water detainers under the garage and a variety of … innovative techniques, minimizing the change in run off patterns.”
The $12 million stormwater management system is being financed by a loan from the Ohio Water Development Authority, a state financing agency that started an alternative stormwater infrastructure program with the Ohio Development Services Agency last year. Butler County records show the agencies approved a 20-year loan with a 1 percent interest rate during construction, 2.5 percent after that.
“It fully meets the intent of the program, which was to see these kinds of innovative designs,” said Thea Walsh, ODSA’s deputy chief in the office of energy and redevelopment. “When you go shopping and you see those big retention ponds —you’re not going to see all that (at Liberty Center). It’s not going to be part of the viewscape.”
Environmental and zoning regulations require developers to control stormwater run off from new commercial construction. But fewer than 10 percent of projects use underground storage, said environmental consultant Don Fay.
“Underground retention has been around awhile, particularly in places where space is limited. It’s a better use of the real estate than having a big retention pond,” said Fay, vice president at TRC Environmental Corp. in Blue Ash. “I’ve not heard of any projects where they’re recycling the water for irrigation.”
Steiner + Associates Development Director Justin Leyda said retention ponds would have claimed more than seven acres at Liberty Center, a 1.1 million-square-foot development that aims to bring dozens of retail stores and restaurants to Liberty Township, along with a movie theater, hotel, office and apartment buildings.
By tucking a water storage facility under a parking garage, Liberty Center can regulate the flow of stormwater into the Mill Creek watershed.
“Up to a 100-year flood, it captures all that water,” said Leyda. “So, even in a 100-year storm, the water’s exiting at like a normal one-year storm quality. So, you’re not impacting that stream with this huge gush of water.”
A hole has been excavated for the massive underground storage tank and its steel bones are to be installed in June. The storage facility has two chambers for water from sewer pipes and rooftop gutters. Surface water carries sediment and pollutants that settle to the bottom of one chamber, where it can be scraped out periodically. The rooftop chamber acts like a giant rain barrel, providing water that feeds Liberty Center’s pocket parks.
The storage facility itself will cost between $8 million and $9 million, Leyda said. Pipes leading to the storage tanks add a couple million more to the price tag. Leyda said the system is 10 to 12 times more expensive to build than retention ponds, but it will be easier to maintain over time.
“If you’re going to try to clean out the sediment from a pond, that’s not very easy,” he said. “With ours, you’ve got a concrete box. We can send a machine down there and scrape it out with a dozer … or we can send down a vacuum and just vacuum it all out. So, it’s much more efficient, a much cleaner product.”
Here are the technical specifications for the Liberty Center detention basin, submitted to state officials last year: