Johnson & Johnson’s objective for the Spring House corporate campus was to mitigate the stormwater impacts in connection with the construction of future facilities. A 150,000 sq. feet clinical development, laboratory, and office space addition was announced in May 2007 and will finish construction in 2009. Full build-out of the site will not be completed until 2014. The incorporation of Best Management Practices (BMPs) reduces non-point site pollution and flash flooding in this prone area. These sustainable development practices will reduce the expansion project’s runoff levels by 15% compared to pre-development runoff rates. The porous pavement parking lot has been completed, but the wetlands are not yet under construction.
Integrated into Johnson & Johnson’s site expansion are the following stormwater Best Management Practices (BMPs): Porous pavement and underground infiltration gallery, Bioretention swales, and Constructed stormwater wetlands.
Porous Pavement and Underground Infiltration Gallery
Testing was conducted concluding that the site was suitable for the installation of both porous pavement and an underground infiltration gallery. Percolation testing determined that the infiltration rate would be 1.04 inches per hour and that the two elements would capture about 42% of stormwater volumes. For a diagram of a typical porous pavement section with underground infiltration gallery, please click here. The subsequent project phases to incorporate other BMPs like bioretention swales, wetlands, and other non-structural methods are meant to retain or filter the remaining runoff.
The construction of the porous pavement included the digging of divided subsurface water storage cells, measuring 60 feet by 60 feet by an average of 3 feet deep. These cells were lined with geotextile fabric. Before AASHTO No. 1 gravel was put in place, perforated pipes connected to the main storm sewer pipes were set at different grades to provide conveyance and diffusion of stormwater into the storage cells. Only one building under construction is presently hooked up to the system; per the master plan, the storage capacity of this reservoir anticipates all future runoff volume from buildings at subsequent stages of site development.
When the underground infiltration gallery reaches its maximum storage capacity excess stormwater flows through a custom “upwell” pipe relieve system. The stormwater is filtered through graded vegetated swales before flowing into stormwater drains. Native shrubs, trees and ornamental grasses, all salt and moisture tolerant, were planted in the parking lot islands to both absorb stormwater volume and dissolve common pollutants from vehicular traffic. The swales were covered with decorative gravel (river stone) for maintenance purposes. The porous asphalt works so well that these swales do not encounter much runoff. For a list of native plants used on the islands in between the parking lot bays, please click here.
Constructed Stormwater Wetlands
This is a future project, expected to be completed after 2014. Details will be added as they become available.
Watershed: Neshaminy Creek
The 101-acre Johnson & Johnson Spring House corporate campus is located at Welsh and McKean Roads in Spring House and is the hub of East Coast clinical research development.
Manager of Global Environmental Affairs