• This redevelopment project reduced impervious surfaces on the site by 43%, from 9.26 acres to 5.30 acres.
• All existing pavement on the site was crushed and reused for sub-base below paved areas and for bulk aggregate fill. The site contained approximately 2,700 cubic yards of asphalt, 2,410 cu yd of concrete, 7,020 cu yd of aggregate stone sub-base, and 370 cu yd of railroad ballast.
• A series of four rain gardens filter and infiltrate stormwater runoff from the building and porous parking lot. One lined rain garden is on the street side of the building; the other three are unlined. The rain gardens are designed as wet plant communities and are eye catching aesthetic features.
• Carved granite runnels capture air conditioner condensate and carry it to a cistern and rain gardens.
• The site was designed as native plant communities with upland, lowland and wet habitats. Dragonflies, bees, other insects and some bird species have been observed on the site post-planting.
• A small urban farm dedicates a third of an acre to growing produce and has an outdoor classroom for educational programs.

Challenge:

The site was a former industrial brownfield with contaminated soil and zero permeability due to its most recent use as a parking lot. Virtually all of the stormwater generated on the site drained untreated into the municipal sewer system. The soil contained toxins, such as benzo-pyrene and various metals derived from slag from former industrial activities. The paved area was vast and its off-site disposal would contribute negatively to local landfills and require energy to transport the waste materials.

Solution:

The landscape architect chose to strive for a zero net waste approach to site construction. The design intent was for certain contaminated soil to be buried deeply on the site, which was achieved through a creative and complex grading scheme. (Regulation required that some toxic soil be disposed of off-site.) Nearly all of the site’s existing pavements were reused onsite. Approximately 12,500 cubic yards of materials were recycled and integrated into the construction of the parking areas, synthetic turf base, lawn base, paths, and structural fill. By determining the equivalent performance capabilities of the type of aggregate debris, each could be specified for maximum benefit at the site. The site was graded to include several rain gardens, which capture and filter the first inch of stormwater.

• Through extensive use of recycled materials and limited off-site disposal, the site was able to be developed for less than $19 per square foot.

• Contaminated sites require import of specialized soil. It is important to ensure that the soil is what was specified by conducting on site testing during landscape construction.
• Technologies such as cisterns and approaches to landscape (i.e. native plant communities), require client and staff education to ensure proper operation and maintenance. Landscape designs intended to act as living systems and to perform stormwater mitigation require attention in their early years. The project landscape architect provides regular assistance to the Salvation Army on a pro bono basis. He does this to ensure that irrigation and cisterns are functioning properly, that rain gardens are being cared for properly, that the landscape is being managed organically. He also wants to ensure that the client understands how to use the site systems to reduce costs and improve sustainability.
• Sustainable landscapes need comprehensive management plans and regular post occupancy attention to ensure that the ecological integrity of the site is maintained over time. The current PSI number indicates high ecological quality a year after the project was completed. That can change. Invasive species will come in from other sites and from the adjacent railroad corridor. Maintaining native plant communities requires diligence and field knowledge from both the landscape architect and landscape crews.
• With systems that the client will operate, such as irrigation, useful and accurate operation manuals should be required. At the time construction is completed, these systems should be tested and demonstrated with the contractor, landscape architect, and client in attendance. Collaboration between the system designer and the landscape architect is encouraged to facilitate ease of operation, observation, and maintenance. Irrigation systems require fine tuning and monitoring for success and must be designed to facilitate these activities.

Project Team:

Landscape Architect: Andropogon Associates, Ltd.
Architect: MGA Partners, Inc.
Civil Engineer: Duffield Associates, Inc.
Structural Engineer: CVM Engineers
Cost Estimator: Becker & Frondorf

Role of the Landscape Architect:

The landscape architect performed landscape programming, athletic programming, site planting and circulation design, balancing of cut and fill, grading, contaminated soils management plan, comprehensive stormwater management coordination with the architect and civil engineer, coordination of stormwater cistern and irrigation design team and long-term system management.

Case Study Prepared by:

Research Fellow: Mary Myers, PhD, RLA, FCELA, Department Chair, Temple University
Research Assistant: Andrew C. Hayes, PE, MLA Candidate, Temple University
August 2011