Douglas J. Daley, P.E.

Department of Environmental Resources Engineering

 
 

Research

Green Infrastructure: Rain Garden (Bioretention) for Managing Roof Drainage

Project Location: SUNY ESF, Syracuse, NY

Sponsor: USDA McIntire-Stennis

SUNY ESF Illick Hall bioretention cell

A bioretention cell 14’ W x 35’ L was constructed in the summer 2008 at the southeast corner of Illick Hall on the SUNY ESF main campus. The cell was designed to provide 0.5’ ponding depth for a peak flow of 2.1 cfs (100-year return interval). Native plants are supported by a 0.5’ mulch layer over 3.5’ planting soil over 2 feet compacted granular subbase. The cell receives drainage from approximately 10,270 square feet of the Illick Hall roof through a 2.5 x 4.0 ft influent weir box. A trench drain, which connects to the local storm sewer, underlies the bioretention cell. The cell was equipped with sensors to monitor flow, soil moisture and temperature in Spring 2009. Instrumentation is listed in Table 1. Water level sensors will be used in combination with V-notch weirs to measure influent and effluent flow.

Green Infrastructure at SUNY ESF

students have used the following resources for either undergraduate or graduate research projects.

SUNY ESF Porous Pavement

SUNY ESF installed a porous pavement (trade name Flexi-pave) in summer 2008 on an elevated walkway at Moon Library. The installation offers the advantage that the water which permeates the pavement is conveyed to an underdrain system, where the flow and/or volume can be measured at four outlets. Flexi-pave is a flexible paving material comprised of 3/8” (8mm) wire-free recycled tire granules, 3/8” to ½” aggregate and a proprietary binding agent. Installed depth is generally 1 to 2 inches. Flexi-pave advocates claim that its high porosity  reduces runoff to storm sewers and stormwater retention facilities.

SUNY ESF Green Roof

The SUNY ESF green roof installation on Walters Hall was completed c. 2005. Planting medium was installed over a PVC roof membrane. Plants are predominately sedum planted at 12” o.c. in approximately 6” of M-2 growth medium. An adjacent roof is covered with conventional builtup membrane roof materials. Some minor retrofit of the roof drain leaders will be needed in order to measure flow rate and obtain water quality samples from the two roof systems.

An urban watershed weather station is installed on the green roof (http://weather.esf.edu/ESFweather.htm) which provides current climate data.

TABLE 1: Instrumentation

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News:

August 22, 2010: Syracuse experienced a signficant rain event sustained for about 24 hours and over 10 cm inches of rainfall. The rain garden held substantial water volume, at least 15 cm deep, but even this type of event needed to go somewhere, in this case over the outfall weir. This was the second time in a week that the rain garden overflowed the outlet, and only the fourth time in my recollection since the garden came on line. Note the vegetation growth over two seasons and how readily the garden softens the hard edges of the quad.

April 2009: A new interpretive sign will be installed this summer to inform campus visitors. See the near final version by following the link (PDF) to Illick Raingarden Interpretive Sign_DRAFT

October 2008: The bioretention basin adds color to the campus.

July 2008: Planting is completed and the bioretention basin operational.

June 2008: The bioretention basin walls are pured and ready to be backfilled.

May 2008: the 6" underdrain is installed along the south face of Illick Hall.