C — September 27 - October 10, 2013 — Shopping Centers — Mid Atlantic Real Estate Journal


R etail S ervices & ICSC H ighlights

ne of the many chal- lenges property own- ers face is how to im- By Christopher Gubeno, P.E., Urban Engineers Design concepts that hold water: Cost-effective stormwater retrofits for commercial properties O

prove their p r o p e r t y ’ s sustainabil- ity, stormwa- ter manage- me n t , and overall vis- ibility and at- tractiveness. This can be accomplished

Existing Shopping Center

After Applying Stormwater reStore

• 10 Acres • Five Trees

• 92 Trees • 1,270 LF of Greenway along Adjacent Roadway • 21,875 CF of Infiltration or Storage of Stormwater Runoff • 129,100 SF of Pervious Surfaces & Plantings

Christopher Gubeno

• 92,100 SF of Pervious Surfaces & Plantings • No Infiltration or Storage of Stormwater Runoff

through adopting green storm- water retrofit features into current retail, commercial, or industrial sites, which can pay dividends with reduced operat- ing and ongoing maintenance costs. The following case study presents scalable, cost-effec- tive stormwater management and pedestrian friendly design strategies that can transform retail shopping centers, com- mercial centers, and industrial facilities into sustainable, com- munity-oriented sites. The overarching design concept, called Stormwater reStore, is a prototype for future green stormwater infrastructure projects and demonstrates the return on investment of such projects for property owners. A Closer Look: Grays Ferry Shopping Center The basis for the Stormwater reStore design is the Grays Ferry Shopping Center located in Philadelphia, PA. This prop- erty is typical of the 1980’s and 1990’s bleak shopping centers that include large parking ar- eas with buildings set far from the roadway and entrances. These sites are more vehicle than pedestrian friendly and usually present minimal and poorly maintained landscap- ing and trees. The Stormwater reStore design leverages high performance landscaping, such as rain gardens and native vegetation, along with out- door community spaces and improved community connec- tivity to draw people into the shopping center while creating a gateway to the neighborhood, sparking redevelopment along the adjacent roadway, and improving stormwater man- agement. This 10-acre property comes with a $3,400-per-month stormwater bill because of the vast amount of impervious sur- face area on the property. The proposed stormwater manage- ment features would bring the bill to $550 per month, an 84% reduction.

The Design Process The Stormwater reStore design process evaluated a comprehensive list of sustain- able stormwater features that could be used to achieve these three objectives: • Create cost-effective op- portunities to improve the stormwater management on the site, adjacent properties, and roadways; • Create a more inviting and pedestrian friendly property; and • Identify cost effective, en- ergy reducing, and sustainable building and site initiatives. There were a number of solu- tions that included bio-swales, rain gardens, infiltration beds, underground stormwater infil- tration and storage systems, porous pavements, green and blue roofs, green screens, dis- connection of the building and parking lot stormwater systems, and capturing storm- water runoff for reuse in land- scape irrigation. Selected strategies included only those that provided the highest return, were adaptable on other sites, did not require significant building or site modifications, and could be phased to minimize impacts to the property and parking lots. The resulting design concept reconfigures the drive aisle widths in the parking lot to incorporate rain gardens and bio-swales between rows of parking. The conversion of an existing unused pad site and a portion of the central entrance driveway into educational and public gathering space cre- ate additional opportunities for stormwater storage and infiltration. The design also includes a green corridor along the adjacent roadway as a pe- destrian friendly streetscape. Other stormwater infra- structure improvements such as green or blue roofs, and pervious pavements alterna-

tives were not incorporated due to their high cost and ef- fort to install when compared with their impacts on overall sustainability. Stormwater reStore Key Features The Stormwater reStore design incorporated these sus- tainable and pedestrian friend- ly features. • Energy Reducing and Sustainable Building Ini- tiatives Incorporating solar power and LED fixtures into the external building and site lighting provides a signifi- cant long-term savings for a relatively low installation and implementation cost. Installing solar power and LED fixtures in addition to low flow fixtures inside buildings is also rela- tively minimal in cost and can be implemented during annual maintenance of the facility. • Pedestrian Friendly and Community Oriented Design Providing pedestrian friend- ly paths and incorporating community oriented ameni- ties are important and unique components of the Stormwater reStore design, in that they also serve as stormwater man- agement features. The design includes improved pedestrian routing and areas for public gathering spaces that include an outdoor café or community pop-up market, in addition to local trail connections. • Greening the Site and Local Roadway Connec- tions Streetscape improvements along the adjacent roadway en- courage pedestrian movement in the area and strengthen the connection to nearby shops, paths, and trails. By modifying the street frontage and using existing excess parking that may not be needed (except to meet zon- ing codes), widened pedestrian

Renderings credit: Mathews Nielsen Landscape Architects

walkways can accommodate street trees and rain gardens that act as a buffers between the roadway, sidewalk, and parking lot. The addition of trees, shrubs, and native veg- etation, improve the look and feel of the property, making it more inviting while provid- ing usable outdoor gathering spaces. • Roof Drain Gardens The roof of the shopping cen- ter is approximately 1.8 acres in size and drains directly into the stormwater system that extends around the rear. The roof drainage presents an enor- mous opportunity for stormwa- ter collection. By repurposing unused or underused areas around the edges of the build- ings or site, the stormwater runoff can be rerouted into landscaped stormwater basins or underground storage and infiltration basins. If the larger unused or un- derused areas are envisioned as a community amenity, the site could operate as a stop for bicyclists or pedestrians and serve as an opportunity to incorporate tables and chairs and provide space for outdoor gathering. • Capture Islands With an oversized parking lot, it becomes possible to cre- ate space for rain gardens and

plantings between the park- ing rows by reconfiguring the parking and drive aisles and reducing the number of park- ing spaces. The rain gardens can be introduced without a complete regrading and resur- facing of the parking lot. They serve to intercept stormwater runoff before entering the ex- isting stormwater system. Adding trees and vegetation in the parking lot mitigates the urban heat island effect and also removes pollutants from the air. Additionally, the vegetation adds a pedestrian scale to the site and a more inviting parking experience for the visitor. Summary The Stormwater reStore design concept works because it is generally adaptable to retail shopping centers, com- mercial buildings, or any site with large parking lots. Ap- plying any of the strategies or features mentioned on an existing site not only improves the stormwater management for the property and other properties downstream, but also creates a more sustain- able and inviting facility. Christopher Gubeno, P.E., is the director of land development for Urban Engineers. n

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