Shoemaker Green is a 3.75-acre site surrounded by two of the University of Pennsylvania’s most iconic athletic facilities, the Palestra and Franklin Field. At first glance, the site appears to be a typical collegiate quad space. However, it is actually a high performance landscape that absorbs, cleanses, and stores stormwater. Stormwater is captured through a series of trench drains and inlets that release the water by gravity into several feet of designed soils under the main green space. The vegetation within the lawn area removes a portion of the water through evapotranspiration. The remainder of the water percolates down through the sand-based soils, which act as a natural filter and remove pollutants from the water. The water is then collected at the bottom of the drainage layer through an innovative under-drainage system, a Smart Drain™, which wicks up water through capillary action, further removing particulate matter from the water. The system then conveys the water to the cistern for storage and reuse for irrigation.
Water that is not captured within the main green area is conveyed to a large rain garden at the bottom of the site. Water is released into the rain garden through a series of custom-designed trench drains. The water meanders through a series of vegetated and stone-lined swales and collects at a weir structure. The water then spills over the weir and is infiltrated into the designed soils and used by the native mesic plant community. Water that is not used by the plant material is collected in a similar fashion as described above and conveyed to the cistern.
Stormwater best management practices (BMPs) on the site include a large subsurface stone, slow-release storage bed and a slow-release bioretention area. The varied and sometimes exceedingly high infiltration rates throughout the site precluded the use of infiltration for stormwater management. All of the BMPs have been sized to provide the capacity to store the 1-inch water quality volume and to release stored runoff at a controlled rate as required by the Philadelphia Water Department (PWD).
The storage bed below the lawn is an aggregate storage that was installed directly over a large section of the existing tennis courts, which remained in place. This bed is located under approximately 36-inches of well-draining engineered soil and a newly planted lawn area. The existing paved tennis court surface prevents infiltration and allows the storage bed to function as a slow release detention system. A compacted earthen berm at the low end of the storage bed allows stored runoff to back up and reach bed capacity before discharge from the system. A slow release Smart Drain™ system allows the bed to slowly release stored runoff at rates below the allowable release rates for combined sewer areas. An emergency overflow was designed to allow for large storms to discharge from the system when the storage bed has reached capacity.
The slow-release water quality bioretention area is lined with a flexible impervious liner to prevent infiltration. The bioretention system is designed with a minimum of 36-inches of highly absorptive engineered planting soils and will pond to a maximum depth of 3-inches. The area is sized to provide storage for the 1-inch water quality volume and is also drained utilizing the Smart Drain™ under-drainage system and will release stored runoff at rates below the allowable PWD release rate for combined sewer areas. The bioretention area also provides water quality treatment and volume control as a result of evapotranspiration.
Funded via a student-composed application to the University of Pennsylvania’s Green Fund grant program, Shoemaker Green has the opportunity to become what green infrastructure seldom is: a monitored, high performance landscape that captures, filters, and effectively delivers clean water back to the environment. A five-year monitoring plan has been developed to allow landscape architects Andropogon Associates, University of Pennsylvania students and staff, and even the general public to interact with a truly “living system.” By examining the impact that integrated BMPs have on filtering stormwater, we can continue to effectively capture water, filter it, and deliver it safely back to the watershed.
Though it is too early to release conclusive data results, the site can offer some lessons learned regarding equipment costs and planning stages for monitoring. A monitoring plan was developed by Andropogon Associates for the University to identify monitoring processes and needed equipment. In January of 2013, a grant in the amount of $11,140 was awarded to the Department of Earth and Environmental Studies (EES). The monies were provided to purchase equipment and any necessary laboratory testing, no staffing costs were included. A project kick-off meeting took place in February and included representatives from Facilities and Real Estate Services, EES (staff and students), and Andropogon Associates (designer). Details of the proposed Shoemaker Green monitoring program, including project background, equipment list, monitoring parameters, and schedule, were presented. Funds for the equipment acquisition were transferred to the department in February 2013, and equipment was ordered in March 2013. The primary equipment procured included: pressure transducers, infiltrometers, tensiometers, stormwater grab sample bottles, an automatic stormwater sampler, a leaf porometer, an LP-80 to measure photosynthetically active radiation, a penetrometer, miscellaneous installation equipment such as suspension cable, NDS valve boxes, and various hardware.
In May, students and University staff installed the equipment. To date, stormwater quality measurements have been obtained for two storm events, stormwater quantity has been retrieved for the month of June, transpiration measurements have been taken once, compaction readings have been accessed three times, and behavior mapping has begun to understand how people use the site, all completed without monetary compensation. A significant amount of collaboration and commitment has been necessary to coordinate this unique partnership between University staff, students, and the site design team.
Watershed: Schuylkill River
Shoemaker Green is located on the University of Pennsylvania campus in Philadelphia, PA, in the Lower Schuylkill River Watershed.
Andropogon Associates – Landscape Architecture
Meliora Environmental Design – Engineering
Tim Craul – Soil Scientist
Monitoring Partnership – University of Pennsylvania: Craig Calabria Ph.D.,P.E., Faculty Advisor;
Grant Scavello, Master’s Candidate; Pablo Garza, Master’s Candidate
Andropogon Associates Ltd, Principal
10 Shurs Lane
Philadelphia, PA 19127