Limited local water supplies and recent droughts have highlighted the need to reduce water consumption across campus. Investments in reclaimed water, harvested rainwater, and water efficiency have reduced Carolina’s potable water use by 60% per square foot since 2000. Both the UNC campus and UNC Hospitals are more resilient to drought and supply disruptions from which the entire community benefits. In 2009, a reclaimed water system became operational that has helped to decrease potable water usage and costs.
Reclaimed Water and Non-Potable Water
In 2009, a reclaimed water system, developed in partnership with the Orange Water and Sewer Authority (OWASA), started providing cooling tower make-up water for the University’s chilled water plants, the largest water use on campus, and for athletic field irrigation. All five chilled water plants, accounting for 200 million gallons per year, or 25 percent of the University’s total water use, are connected to the “purple pipe” reclaimed water distribution system. As of FY 2015, nonpotable water accounted for 27% of UNC’s total water use, up from 4% in 2009. Chiller plants at the UNC Hospitals, which use 90 million gallons of water per year, are also served by the system. In addition, reclaimed water irrigates several NCAA athletic fields, using 10 million gallons of water per year, and flushes toilets in new buildings located near the distribution network, such as the Genome Sciences Building and Kenan Stadium.
Record 100-year droughts in both FY 2003 and FY 2008 highlighted the vulnerability of the hospital, the medical research facilities, the campus, and the town as a whole to water shortages. By investing in wastewater reclamation, OWASA and UNC will ultimately reduce the demand on the community’s potable water supply by 10 percent. UNC provided the funding for this system, investing more than $10 million in reclaimed water infrastructure to date.
Reclaimed water is highly treated and dually disinfected wastewater from the Mason Farm sewage treatment plant that is pumped to the University. The first UNC customer along the route is the LEED Platinum Botanical Garden Education Center, where the water is used to flush toilets. At the chiller plants, the reclaimed water is circulated through cooling towers that discharge the waste heat from University buildings. The water recirculates through the system six times, requiring 17% make-up water during each cycle. At the Genetic Medicine building, foundation drain water is recovered for use in the neighboring cooling tower at the South Chiller Plant. In 2008, the roof drains for the South Chiller Plant Annex were redirected to the cooling tower basin, providing 7,000 gallons of make-up water after each inch of rain.
Reclaimed water at UNC is integrated with the extensive rainwater harvesting program to create a unique, non-potable water supply system. At the former Bell Tower parking lot, an integrated, non-potable water system features a comprehensive water management strategy. Rainwater that falls on the roof of the Genome Sciences Building, is stored in a lined, stone-filled cistern capable of storing up to 350,000 gallons of water. This clean roof water is used to flush toilets in the Genome Sciences Building and Kenan Stadium and to irrigate the football field. If there is not sufficient rainwater for these purposes, reclaimed water is used as the backup water source.
A range of innovative stormwater management strategies significantly reduce sediment and nutrient loading in area watersheds and prevent downstream flooding.
Underground cisterns hold rainwater to irrigate the intensive green roof at Rams Head Plaza and Fetzer Field. There are two cisterns installed under the historic quad in front of Hanes Hall and beneath the parking structure at Boshamer Stadium. The cistern at Hanes is unique in that it is not provided with backup water from OWASA. The cistern at the Boshamer baseball stadium is the first to capture water used to irrigate the turf. This recycles the fertilizer and avoids sending nutrients downstream. The Boshamer cistern is also the first to use reclaimed water as a backup. The FedEx Global Education Center is the first building on campus to use rainwater to flush toilets. The Genome Sciences Building also features a 350,000 gallon cistern that captures rainwater from the roof to be used as reclaimed water.
Permeable pavement is another structural approach to stormwater management that has been employed extensively at Carolina. Gravel beds under the porous surface store rainwater until it slowly infiltrates into our clay soils. The soil then filters out pollutants conveyed from the parking lot. Porous pavement is installed at both the 800-space Friday Center park-and-ride lot and a remote parking lot for students with 465 spaces. The University saved approximately $500 per parking space in these lots by selecting a permeable pavement system instead of building an additional detention basin or drainage system. Additional porous asphalt lots have been installed at the Facilities Complex, on Cameron Avenue across from the cogeneration plant, in front of the EPA building on campus, and at the Hedrick lot. The park and ride lot in Chatham County is a porous lot designed to infiltrate into a sandy soil layer.
Coupled with infiltration beds and permeable pavement, there are now more than 180 structural best management practices installed across the campus. Energy Services maintains an inventory of all stormwater management features installed to date in the University’s geographic information system (GIS) that identifies the location and type of each installation. This facilitates long-term maintenance of the University’s large and growing stormwater system.
Water supply shortages, new water quality rules, and campus growth are driving this unprecedented and comprehensive approach to water management. As part of a $2.3 billion capital improvement program, UNC has completed the construction and renovation of 7.5 million square feet of space since 2010. This is more square footage than exists on most college and university campuses and equals 56 percent of UNC’s space in 2000. This expansion has occurred at a time when local, state and federal government agencies are working to regulate more stringently both the quantity and quality of stormwater runoff.
In addition to common stormwater management requirements for flood control and total suspended solids removal, the University also controls volume and nutrients. Infiltrating stormwater and harvesting rainwater for reuse benefits groundwater recharge and downstream habitat and reduces the volume of stormwater leaving campus following rain events. Regional Jordan Lake rules limit the amount of nutrients, namely nitrogen and phosphorous, leaving new development. The rules also require a 35 percent reduction in nitrogen runoff from existing development. The University is identifying retrofits in the current stormwater system to meet this goal.
To coordinate UNC initiatives designed to comply with these rules, a full-time stormwater engineer was hired by Energy Services in 2008. At Environment, Health and Safety (EHS), a water quality specialist was hired to monitor stormwater runoff and to educate members of the UNC community. Grounds Services staff maintains the stormwater infrastructure, including quarterly vacuuming of the University’s seven permeable pavement parking lots.
One of the requirements of the University’s National Pollutant Discharge Elimination System permit is to raise community awareness of the importance of stormwater management. Some of the outreach strategies to date include training sessions for shop staff, information tables at on and off campus events, and a new stormwater management website. To date, over a thousand University employees have participated in stormwater training sessions. Storm drain signage across campus asks people to refrain from dumping any waste products, and multiple creek cleanups are held each year.
The restoration of Chapel Creek is another effort to improve water quality. Approximately 1,400 linear feet of stream channel and five acres of riparian buffer were reconfigured to allow the creek to access its floodplain again and meander in a natural way. This project, on an unused portion of the old Finley Golf Course, was supported by the N.C. Ecosystem Enhancement Program and will provide educational opportunities in stream restoration processes. The entire area, currently used for running trails and environmental education, was replanted with a variety of native plants. A conservation easement was created to protect the area permanently.
- UNC Stormwater Management Overview
- UNC Energy Services
- UNC Environment, Health and Safety
- N.C. Ecosystem Enhancement Program
Potable Water Conservation
To reduce the demand for potable water, efficient fixtures and systems are being installed across campus. Some 330 toilets in 57 buildings have been retrofitted with dual-flush valves that reduce water consumption per flush by up to 0.5 gallons, or 30 percent. The savings result in less than a four-year payback. Recent retrofits have placed 47 pint urinals in campus buildings. At 1/8 gallon per flush, these urinals use 88 percent less water than the N.C. Plumbing Code allows. In the residence halls, water flows through 90 percent of the 2,640 showerheads at the rate of 1.5 gallons per minute or 40 percent less than code. Aerators are in place in 90 percent of the residence hall lavatories. Seventy percent of the washing machines are Energy Star certified, meaning they use both less water and less energy.
At the new Facilities’ Service Station completed in 2007, the wash bay was designed to recirculate 70 percent of the wash water. A clarifier filters out the solids and the heavy liquids such as motor oil and grease. Even the soap is reclaimed and recycled. Then, an ozone generator treats the water for reuse. Water used to clean the floor in the five service bays is also sent through the recirculation system. Once a year, the system is pumped out and the captured oil and grease are recycled.
Carolina Dining Services permanently discontinued using dining trays in 2007, saving 12,000 gallons of water per week and 500,000 gallons annually. After piloting trayless dining at UNC, the school’s dining contractor introduced the program to other customers nationwide. Additionally, the food pulper in Lenoir Dining Hall extracts and reuses 95% of the water removed from food waste, which reduces the weight and cost of transporting the food waste for composting.
Planting strategies and many existing landscapes have been modified to support low-maintenance, water-retentive landscapes. New irrigation systems apply water directly to the plant to eliminate evaporative losses. A centralized weather station electronically monitors 12 variables, including relative humidity and rainfall, and controls 21 irrigation controllers. This data is relayed by radio to the irrigation controllers. The amount of water used for irrigation is measured down to the gallon at each station. When water consumption figures are higher than anticipated, grounds technicians investigate for leaks or broken timers.