For this subsurface stormwater system in East Whiteland, Pa., engineers from Nave Newell chose to install an extensive bed, which included over 700 Cultec Recharger 330XL???(R)???AE???? chambers placed in 45 rows.

When CubeSmart, the fourth largest owner and operator of self-storage facilities in the country according to the 2011 Self Storage Almanac, decided to relocate its corporate headquarters to East Whiteland, Pa., they were required by both township and state regulations to install a stormwater management system.

Engineers from Nave Newell, Inc., based in King of Prussia, Pa., were given the task. The team collaborated with contractors at Lyons & Hohl Site Contractors to develop the system and was faced with a number of onsite challenges including a 60-foot topographic grade. Also, the site is the last piece of land to be developed at a prominent intersection and is located at the top of a steep bluff. Because of this, engineers were under close scrutiny by the township, county and state regulators and stakeholders, and had to be mindful of the quality of the receiving watershed.

Nave Newel engineers selected the Cultec stormwater system to detain, or temporarily store excess stormwater onsite, and allow for infiltration in accordance with regulations. Because of the bluff, the engineers had to be very careful in establishing the discharge location. Runoff could not be discharged directly over the side of the bluff for fear of erosion down the slope.

"We knew that any consistent flow of runoff going over the side of the bluff would eventually cause it to erode and set other potential dangers in motion," said Alex Tweedie, Nave Newell design engineer. "In order to prevent any chance of erosion, a pipe was extended outside of the area to create a discharge site that would be able to adequately receive the runoff."

Given the constrictions of the site terrain and the storage requirement of 93,397 cubic feet, Nave Newell engineers chose to install the Recharger 330XL???(R)???AE???? model for the system. Each unit is 52 inches wide by 30.5 inches high and has an installed length of 7.5 feet long with a bare chamber capacity of 7.5 cubic feet per linear foot. In all, the subsurface Cultec system provided 94,319 cubic feet of storage.

"We prefer to install an open chamber system over a pipe system because you get a much better overall footprint," said John Hogan, Nave Newell design engineer. "The Recharger 330XL is a very efficient chamber which has a lower volume in the early stages of a storm."

Lyons & Hohl Site Contractors installed the subsurface system in under three weeks. The extensive bed included over 700 chambers placed in 45 rows. Moreover, Cultec's No. 410• Filter Fabric encases the entire bed. The fabric prevents soil intrusion into the chamber bed. The system occupies 33,088 square feet. It also required 7,264 tons of stone, which provided a 40 percent void for the water. The void spaces between the stone add to the storage provided while also assisting in alleviating the load above the system.

"Cultec's chambers are created out of lightweight polyethylene making the installation fast and efficient," said Mike Hohl, project manager at Lyons & Hohl Site Contractors. "The entire system was installed with only a handful of workers. The chambers are durable and corrosion-resistant and their interlocking connections help facilitate a fast and foolproof operation."