Facilities (Campus Spaces)

Catching the Rain

capturing rainwater

PHOTO COURTESY OF C&S COMPANIES

College sports fans are no doubt familiar with the Carrier Dome, which has been featured in countless live television broadcasts of the home-team Syracuse Orange football, basketball and lacrosse contests. The Dome, as it is simply known to Syracuse University (SU) and surrounding community, has gotten several facelifts in its now almost 35 years of existence. A new, nearly complete improvement project there will show less obvious benefit to fans in attendance, but sustainability champions are cheering nonetheless.

The Dome is a 50,000-seat, air-supported sports stadium. It is one of the last remaining air-supported stadiums of its kind in the U.S., and the largest on any college campus. Beyond SU athletics, the facility hosts annual high school football championships, marching band competitions, national recording artist concerts, special entertainment events and community activities. Sitting atop the mega-structure is a 6.5-acre Teflon-coated, fiberglass roof.

More than six and a half million gallons of rainwater are estimated to fall on the Dome roof annually. This fact led university officials to wonder if rainwater harvesting technology could help alleviate some of the burden placed on municipal water systems currently serving the facility. A resultant feasibility study determined that water collected from the roof runoff could indeed be used to replace municipal water for some of the Dome’s plumbing systems, while in turn reducing the quantity of rainwater that flows into Onondaga County’s combined sanitary/storm sewer.

In particular, reuse of this “greywater” was considered ideal for public restroom urinals and toilets throughout the Dome. Glamorous? No. Functional and sustainable? Most definitely.

One of the First

The collection, storage, treatment, pumping and use of the rainwater from the Dome’s roof is one of the first systems of its kind for such a stadium. Runoff from the roof is collected by a large gutter system that runs around the entire perimeter of the Dome and contains a total of 36 roof drains that tie into rain leaders distributed around the facility. The roof and gutter system is also heated to melt snow during the winter months. This provides for a year-round source of available rainwater.

The harvesting system includes rainwater collection infrastructure that utilizes two 25,000-gallon below-grade fiberglass cisterns to collect and store rainwater for use in the public restrooms. The sizing of the cisterns is based on scheduled events and usage per event within the facility. In addition, a treatment package used to treat the rainwater consists of vortex filter/solids separators, UV lights, chlorine injection, two 4,000-gallon indoor day tanks, system booster pumps and blue-colored dye injection.

National codes and local authorities having jurisdiction required a high level of treatment of the rainwater so that it could be used to flush toilets and urinals. The resulting water is close to the levels required for potable water. In addition, the blue dye was required to alert the public that the water was not drinkable.

System controls are composed of a standard industrial grade PLC controller, electronic sensors and valve operators. The vortex solids separators are tied into existing rain leaders to divert solids such as leaves, twigs, bird droppings and other contaminants from the water flowing into the cisterns. The underground cisterns are single-wall fiberglass tanks. A standard (100 gpm) submersible pump transfers stored rainwater from the cisterns to the mechanical room treatment equipment. The treatment equipment consists of a cleanable 100-micron sediment filter, 25-micron bag filter, 120-gpm UV light system, chlorine injection/recirculation within the day tanks and dye injection system. A triplex booster pump, capable of pumping 450 gpm at 90 psi, draws water from the two 4,000-gallon day tanks and supplies the public restrooms to meet the demand.

Overcoming Challenges

Some of the challenges faced during the project included finding a location for the two large below-grade cisterns next to the Dome amongst the large amount of existing below-grade utilities; efficiently packaging treatment and pumping equipment to be effectively positioned for public viewing; and tying into the existing rain leader system with minimal disruption to the facility.

Due to the critical nature of the public restroom water supply system, and the fact that the restrooms cannot lose water supply during an event when 50,000 fans are in attendance, a municipal water backup system was included in the project. This system automatically switches the water supply to the restrooms from rainwater to municipal water when cistern and/or day tank water levels drop to a pre-set level.

Unlike most mechanical systems that serve public buildings, which are typically hidden away from view, this system was designed and laid out to be highly visible and easily understood by the general public. To engage the public in this project and highlight the innovative sustainability measures the university is taking, the system components are put on display. Throughout the system, rainwater piping is bright purple and clearly labeled. The mechanical room, which contains the majority of the rainwater treatment, storage and pumping equipment, was designed with a curtain wall of glass and interpretive signage to allow the public to see the components from the lower concourse of the Carrier Dome.

As with other universities today, Syracuse has integrated sustainability concepts into many of its curricula, and this project posed another learning opportunity that was not to be missed. Therefore, in addition to the technical aspects of designing and constructing the project, several accompanying features are being incorporated to help educate students and the visiting public about rainwater harvesting and other sustainable practices throughout the university. These items include: colorful wall murals within the restrooms, with graphics and text discussing rainwater harvesting; the aforementioned purple piping that can be tracked within the Dome; and a large touchscreen kiosk outside of the mechanical room glass wall that interacts with colored LED spotlights to highlight specific equipment as it is being profiled.

This highly visible display of the rainwater system provides a rare opportunity to offer a richly diverse sector of the public to see what the engineering profession can and does create, and how that profession benefits not only the campus, but also the community at large.

Looking at the Benefits

The use of rainwater in lieu of highly treated and processed municipal water to flush urinals and toilets not only saves energy, but also helps to conserve one of our most precious natural resources. In addition, the reduction of stormwater entering the county’s combined sewer system helps to reduce pollution in nearby Onondaga Lake. Because of this and other sustainability-driven projects in the area, the lake is improving and on the path to again become a great recreational resource for residents and visitors. Having the lake available for fishing, swimming and boating, along with the development that comes with those activities, will create an economic boost that the university can share with the community.

The reduction in the use of municipal water by the Carrier Dome is, in fact, a cost savings for the university, but that savings is minor taken in context of all the other operating expenses required to run the behemoth facility. Larger benefits include the educational component for the campus community and visitors, along with the positive public relations by which SU demonstrates its commitment to sustainability. Because the Carrier Dome is nationally known, that public relations component travels far.

The engineering design consultant and Syracuse University worked closely as a team during the entire project, from investigation through design and during the construction process. This close working team relationship allowed the university to incorporate specific items into the design that will allow for ease of maintenance and operation of the completed system well into the future.

Final construction cost for this innovative project, to be completed this month, is approximately $1.25 million.

This article originally appeared in the November 2014 issue of College Planning & Management.

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