Stormwater Storage for CubeSmart Headquarters

Aug. 3, 2013

CubeSmart, the fourth largest owner and operator of self-storage facilities in the country according to the 2011 Self Storage Almanac, is a self-administered and self-managed real estate company focused on the ownership, operation, acquisition, and development of self-storage facilities in the United States.

CubeSmart owns or manages 479 self-storage facilities across the country and operates the CubeSmart Network, which consists of approximately 850 additional self-storage facilities. The company’s services include storage customization, logistics services, comprehensive moving services, organizational services, and office amenities. Its self-storage facilities are designed to offer affordable, easily accessible, secure, and, in most locations, climate-controlled storage space for residential and commercial customers, as well as boat storage and mini-storage.

Recently, the organization chose to expand its presence in Pennsylvania by opening a location in East Whiteland. Originally, the town envisioned that the site would consist entirely of office space, but when CubeSmart chose to purchase the space, the company decided to relocate its corporate headquarters here and use the other half for storage. The space is divided in half, including Class A offices for 160 employees currently operating out of the Wayne, PA, office, and self-storage facilities.

Photo: Lyons & Hohl Site Contractors

Engineers from Nave Newell Inc. were tasked with designing the new location, which would include the installation of a stormwater management system. Nave Newell is a full-service civil engineering, land planning, landscape architecture, and land surveying firm based in King of Prussia, PA. The firm specializes in land development design and approvals throughout Pennsylvania, New Jersey, Delaware, and Maryland.

The engineering team from Nave Newell collaborated with contractors at Lyons & Hohl Site Contractors to develop the new layout for the site and was faced with a number of onsite challenges when designing the stormwater management system. The engineers had to overcome a 60-foot topographic grade to establish the building pad and parking area. In addition, 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 both township and state regulations. Because the site is located atop a steep bluff, 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,” says Alex Tweedie, Nave Newell design engineer. “In order to prevent any chance of erosion, a pipe was extended outside the area to create a discharge site that would be able to adequately receive the runoff.”

Because only half of the site was dedicated to office space, the demand for parking was greatly reduced. Still, engineers were faced with optimizing the grading to create enough level pads for the parking and reserve parking areas. The most efficient solution was to install a subsurface stormwater system. A grass field for reserve parking was placed on top of the stormwater system, leaving space for approximately 100 additional parking spots.

Cultec stormwater chambers replace conventional stormwater retention or detention systems such as ponds, swales, pipe and stone trenches or beds, or concrete structures. The chambers may be used for drywells and may be installed in trench or bed configurations according to site restrictions and client preference. The contact area is maximized by the fully open bottoms and perforated sidewalls. The chambers are typically installed beneath parking areas to capitalize on use of space; however, they may also be placed below grassy areas.

Cultec offers the largest variety of chamber sizes and is able to accommodate almost any site parameter, whether large or small. With sizes from 8.5 to 48 inches tall, the chambers have storage capacities ranging from 0.819 ft3/ft to 17.62 ft³/ft.

Given the restrictions of the site terrain and the storage requirement of 93,397 cubic feet, Nave Newell engineers chose to use Cultec’s Recharger 330XL model for the system. With a capacity of over 400 gallons, this Cultec chamber is one of the largest available. It provided a balance of maximizing storage while using a small footprint and best satisfied the requirements of the CubeSmart site. The unit is 52 inches wide by 30.5 inches high and has an installed length of 7.5 feet with a bare chamber capacity of 7.5 cubic feet per linear foot. Because of its size, the chamber can help save land space and offer design flexibility. In all, the subsurface Cultec system provided 94,319 cubic feet of storage.

Cultec’s chambers are dome-shaped with perforated sidewalls and fully open bottoms to allow maximum infiltration. In addition, 25 HVLV FC-24 feed connectors were inserted into the side portals of the Cultec stormwater chambers to create an internal manifold system. The feed connectors have a larger flow capacity than a 12-inch (300-millimeter)-diameter pipe. Coupled with the plastic stormwater chambers, the manifold created an underground detention field that will hold water until it can be cast out.

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

Representatives of Lyons & Hohl Site Contractors, which specializes in residential and commercial turnkey sitework projects, installed the subsurface system in less than three weeks. The extensive bed included more than 700 chambers placed in 45 rows. Cultec’s No. 410 Filter Fabric encases the entire bed, preventing 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% 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,” says Mike Hohl, project manager with Lyons & Hohl. “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.”

According to Tweedie, Cultec systems were a natural decision due to the nature of the onsite conditions. The subsurface system solved the challenges of the topography while maximizing the space above for reserve parking.

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