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Stormwater Management

Introduction

Consistent with our Campus Plan, the Sustainability Plan proposes an ambitious program of stormwater management that both reduces demand for purchased water by capturing and using rainwater, and helps to preserve the regional watershed by reducing erosion and minimizing stormwater-related pollution.

Figure 15: Stormwater Management Sites on Campus

Stormwater mitigation
The campus features a number of stormwater management sites including green roofs for absorbing stormwater and reducing runoff, stormwater recharge/detention systems under athletic fields, and rain gardens for filtering stormwater runoff. Click to enlarge (.pdf).

Goal & Progress

  1. Goal: Manage stormwater events with an integrated campus-wide ecosystem approach that enhances groundwater recharge, rainwater capture for reuse, water quality, stream health, tree vitality and more natural flows of water in the campus landscape.

    Progress:
    • Rainwater storage and reuse systems are in place in the form of underground storage tanks at Butler College (6,000-gallon) and at the new Frick Chemistry Laboratory (12,000-gallon). 
    • The Butler College green roofs are demonstrating a more than 60 percent reduction in peak stormwater runoff, compared to conventional roofs, according to an academic study. Real-time performance data are monitored by faculty and students (see graph below).
    • Rain gardens have been installed adjacent to the new Frick Chemistry Laboratory to absorb stormwater runoff from the surrounding area and help protect the Washington Road stream from excessive peak flows. The water undergoes bio-filtration and percolates back into surrounding vegetated areas.
    • Stormwater detention capacity is located beneath 1952 Stadium, and Finney-Campbell, Myslik and Plummer athletic fields to filter and retain runoff created by up to a 100-year storm (has a 1-in-100 chance of occurring in any given year). Powers Field at Princeton Stadium also has some capacity to filter and retain stormwater.
    • Several pathways and courtyards on campus, such as Shapiro Walk, Butler Green and Holder, Wilson and Forbes Annex courts, have been constructed to divert stormwater runoff toward planted areas.

Figure 16: Stormwater Mitigation


Figure 16: Stormwater Mitigation: This graph shows stormwater drainage from conventional (red line) and green (green line) mock roof models on Butler College. Peak runoff from the green roof pan occurred later than that of the conventional roof pan and was significantly less in total volume.

(Data courtesy of Eileen Zerba, senior lecturer in ecology and evolutionary biology)

What's Next

Short Term

  • Complete the Washington Road stream restoration (see sidebar photo).
  • Install real-time green roof performance data at the electronic performance dashboard in Butler College.
  • Study impact of Washington Road stream restoration on local water quality and during peak runoff events.
  • Assemble and analyze data on Frick Chemistry Laboratory rainwater and condensate collection.

Long Term

Figure 14: Synthetic Turf Subgrade Detail


Stormwater recharge systems underneath selected athletic fields have been engineered to retain the precipitation expected during a 100-year storm, significantly reducing surface runoff to local surface water systems.
Click to enlarge.




"The new landscape design around the Frick Chemistry Laboratory has transformed the once-20,000-square-foot asphalt parking lot into a diverse extension of the existing Washington Road woodland. The incorporation of two rain gardens will allow stormwater to infiltrate naturally through native plants and porous soil, saving the adjacent woodland stream from the typical stormwater burden of development."
—Michael Van Valkenburgh, Michael Van Valkenburgh Associates Inc., Landscape Architects



WashingtonRdStream

Alana Tornello, a member of Princeton's class of 2012, uses a monitoring probe to collect real-time data about the water quality of Washington Road stream. Tornello was a participant in the Princeton Environmental Institute's (PEI) Summer Undergraduate Research Training Program, one of several sustainability initiatives taking place around campus the summer of 2010. By analyzing the biological, chemical and physical characteristics of the stream, students in the PEI program could draw conclusions about the stream's health and habitat.