Demanding Stormwater Controls in Louisville
The Germantown Mill Lofts project in Louisville, KY, involves extensive renovation of an entire city block in the middle of town. Previously, the site was the location of a cotton mill, dating to 1889. The property now consists of more than 250,000 square feet of apartments, multiuse facilities, and other buildings spread over nearly 8 acres.
Because of a variety of factors, stormwater management had to be very precise. For one, the local stormwater agency, the Louisville-Jefferson County Metropolitan Sewer District, is operating under a federal consent decree due to discharges of wastewater and sewage into the Ohio River and local streams.
“This resulted in a requirement to detain the post-100-year flows down to the predeveloped 10-year flows. That’s why we ended up going with an underground detention system,” explains Eric Senn, engineering manager with Land Design and Development, the engineering firm for the Germantown Mill Lofts project. “We actually had to over-detain.”
Demanding Stormwater Controls in Louisville The Germantown Mill Lofts project in Louisville, KY, involves extensive renovation of an entire city block in the middle of town. Previously, the site was the location of a cotton mill, dating to 1889. The property now consists of more than 250,000 square feet of apartments, multiuse facilities, and other buildings spread over nearly 8 acres. Because of a variety of factors, stormwater management had to be very precise. For one, the local stormwater agency, the Louisville-Jefferson County Metropolitan Sewer District, is operating under a federal consent decree due to discharges of wastewater and sewage into the Ohio River and local streams. “This resulted in a requirement to detain the post-100-year flows down to the predeveloped 10-year flows. That’s why we ended up going with an underground detention system,” explains Eric Senn, engineering manager with Land Design and Development, the engineering firm for the Germantown Mill Lofts project. “We actually had to over-detain.”
Another issue was ground contaminants onsite, ruling out infiltration. According to Senn, HDPE pipe also wasn’t an option for stormwater control. “HDPE pipe just isn’t large enough for what we needed,” he says. “That’s why we went with a metal pipe.
“We ended up going with a closed system for a number of reasons. Because of the contaminants, we couldn’t have infiltration, and because the area uses a combined sewer system, they didn’t want the possibility of having wastewater backing up into the facility.”
Furthermore, the site location was challenging, with a very tight footprint that was locked on all four sides.
Ultimately, the engineers selected a detention system from Contech Engineered Solutions. It consists of 955 linear feet of 78-inch-diameter aluminized steel corrugated metal pipe that provides over 237,000 gallons of water storage.
Among the water-quality units that Contech provided is a Vortechs stormwater treatment system. This hydrodynamic separator works to keep trash, debris, sediment, and hydrocarbons from entering the detention area.
Installation took place over a two-week period in the fall of 2014, using excavators with straps to place the pipe, gaskets and steel bands for the joints, and a rock thrower to backfill around and between the pipe barrels.
Senn notes that since the installation, a number of large storm events have passed through the area, including some that have caused flooding, but the detention system has been working according to plan, without any unpleasant surprises.