Duke University
OP-27: Rainwater Management

University campus is divided into three areas: East Campus, Central Campus and West Campus and totals approximately 1,700 acres. The West Campus area encompasses approximately 600 acres and is generally bounded by public rights-of-way of Erwin Road, Cameron Boulevard, Duke University Road and Anderson Street. West Campus includes the Duke Medical Center, Administrative and Academic Buildings, Athletic Buildings and Playing Fields, Student Fields, Student Housing, Duke Gardens and forested conservation areas. The East Campus area encompasses approximately 90 acres and is bounded by public rights-of-way of Broad Street, Main Street, Buchanan Boulevard and Markham Avenue. The Duke University campus lies along the division line between two major river basins: the Neuse River Basin and the Cape Fear River Basin. The majority of the Duke Campus, including Duke Gardens, flows south into the Cape Fear River Basin. The majority of Duke’s East Campus flows north to the Neuse River Basin. The regulating authority for campus is the City of Durham. In 2004, Duke University submitted a Stormwater Impact Analysis (SIA) with the City of Durham and began to look at stormwater on a regional basis. The SIA model was originally divided into 48 sub-basins and is updated with each project on campus. The SIA model is a cover conditions model and is based on soil type from the Durham County soil survey information. Ultimately each sub-basin was analyzed and assigned a CN value. Cover conditions are updated with each project and CN values are calculated to determine impervious cover impacts or the need for detention. There have been many updates to the original 2004 SIA that added specific water quality requirements for each river basin. In addition to detention, ordinance updates in 2009 and 2010 outlined requirements for the 1-year storm analysis for the whole campus. This update required the original 48 sub-basins to be further sub-divided into 76 sub-basins for the Water Quality Model. The City of Durham also has specific Water Quality Control requirements for Total Suspended Solids, Nitrogen and Phosphorus based on established thresholds for each river basin. Duke’s stormwater facilities consist of the following: • Numerous streams and open channels: All streams have 50-ft naturally vegetated buffer with a 10-ft “no build” zone. • Over 250,000 gallons of cisterns-CIEMAS, CAE, Williams Field, SMART House, PG9 and DMP • Multiple ponds and bioretention areas-Gardens, Golf Course, Smith Warehouse, SMART House, Faculty Club, and Learning Center • A “SWAMP”: Stream and Wetland Assessment Management Park located on south side of West Campus • Reclamation Pond: Supply approximately 100 million gallons/year to Central Chiller Plant and overall reduction of stormwater volume and water quality treatment.

Duke analyzes the impacts of each individual project with a Stormwater Impact Analysis (SIA) model. Projects are analyzed on a pre and post condition for specific stormwater volume impacts of the 2 and 10 year storm at Duke’s property line and the 1 year water quality impacts and protection of natural streams on Campus. Stormwater facilities are designed based on the results of this analysis.

Duke has installed over 250,000 gallons of cisterns across campus. The majority of these systems are used for landscape irrigation or athletic field watering. Duke has also installed a grey water system at the newly constructed Environmental Hall for toilet flushing. Additionally, the Duke Reclamation Pond will come on line in the spring of 2015. This pond will provide approximately 100 million gallons/year of non-potable water to the Chilled Water Plant #2. This pond will provide an overall volume reduction for the 1, 2 and 10 year storm, act as a stormwater harvesting device with water quality benefits/nutrient reduction and reduce demand on the City’s water system. This pond promotes Duke’s Climate Action Plan and the overall water conservation efforts.

Duke has multiple Bioretention cells designed to treat and filter water prior to entering the natural environment. Projects that have incorporated Bioretention cells for stormwater treatment are as follows: • Home Depot Smart House (2 Bioretention Cells) • Learning Center • PG 9 (2 Bioretention Cells) • Marine Lab • Faculty Club (2 Bioretention Cells) Additionally, Duke maintains a 50-ft natural vegetated buffer on all streams. The naturally vegetated areas slow stormwater runoff and absorb water and pollutants.

University Hospital has a lobby-level green roof in the courtyard. Included in the green roof are test plots and sites for green roof plants and mosses. (http://www.dukehealth.org/health_library/health_articles/green_roof) The green roof atop the Home Depot Smart Home insulates the home from the cold of winter and the heat of summer. The roof’s soil also pre-filters water that passes throughout it, removing pollutants picked up from the atmosphere. (http://sustainability.duke.edu/academics/research/smarthouse.html) The French Family Science Center roof includes 15,000 square feet of sod to filter rainwater and cool the building. (http://sustainability.duke.edu/news_events/items/2007_10_30Buildings.html)

A group of Duke University students worked with KB Industries for their Markets and Management Capstone Course to install a KBI Flexi™-Pave demonstration site under two parking space reserved for Duke Zipcars outside of the Bryan Center. The Flexi™-Pave is made from recycled tires. (http://sustainability.duke.edu/news_events/items/2009_04_06FlexiProcessDuke.html)

Duke has employed the use of above and below ground cisterns to disconnect downspouts. This captured volume of water is mainly used for irrigation of grass and landscaping. The following projects have installed cisterns: • Environment Hall: 500 gallon grey water system • Environment Hall: 25,000 gallon irrigation system • Delta Smart House: 4,400 gallons • Ciemas: 71,000 gallon irrigation system • Parking Garage #9: 20,000 gallons irrigation system • DMP/CC: 100,000 gallon irrigation system • Williams Field: 40,000 gallon irrigation system

Duke has multiple Bioretention cells designed to treat and filter water prior to entering the natural environment. Projects that have incorporated Bioretention cells for stormwater treatment are as follows: • Home Depot Smart House (2 Bioretention Cells) • Learning Center • PG 9 (2 Bioretention Cells) • Marine Lab • Faculty Club (2 Bioretention Cells) Additionally, Duke maintains a 50-ft natural vegetated buffer on all streams. The naturally vegetated areas slow stormwater runoff and absorb water and pollutants.

Duke has multiple retention ponds on campus to control stormwater runoff. One large project is SWAMP: Stream and Wetland Assessment Management Park. (SWAMP) is located on the south side of Duke’s campus on a restored section of Sandy Creek in the Cape Fear River Basin. Duke’s Nicholas School of the Environment , Wetland Center, and the Pratt School of Engineering undertook the SWAMP ecosystem project as a research and laboratory project. SWAMP system consists of restoration of degraded streams, construction of a stormwater reservoir, and construction of a treatment wetland area. Components work as an overall system to treat stormwater runoff from approximately 1,361 acres to address the water quality problems in the Upper Sandy Creek watershed. This includes approximately 253 acres of total impervious surface (Duke & non-Duke) Reclamation Pond: The total drainage area to the pond is 265 acres and 135 impervious acres. Drainage area represents approximately 22% of total Campus. The overall benefits are as follows: Benefits: Water volume reduction • 1-year storm (64% reduction) • 2-year storm (54% reduction) • 10-year storm (40% reduction) Will act as a stormwater harvesting device Water quality & nutrient reduction (N, P, TSS) Reduced demand on the City’s water system Promotes water conservation efforts Restoring approximately 3000’ linear feet of degraded stream section Educational Benefits: Informational signs will serve as educational tool for the environment

Duke has established a proactive approach to natural resources on campus. Duke has restored approximately 2 miles of stream in connection with the SWAMP project and Reclamation Pond project. These were highly degraded streams as a result of years of development in an urbanized setting. These streams were essentially disconnected from the flood plain prior to the restoration efforts. Duke established this approach as a reinvestment in our natural resources and holistic approach to stormwater on campus with a focus on watershed based design techniques.

The University uses cisterns and stormceptors on campus for TSS removal. The university also has begun SWAMP: Stream and Wetland Assessment Management Park. (SWAMP) is located on the south side of Duke’s campus on a restored section of Sandy Creek in the Cape Fear River Basin. Duke’s Nicholas School of the Environment , Wetland Center, and the Pratt School of Engineering undertook the SWAMP ecosystem project as a research and laboratory project. SWAMP system consists of restoration of degraded streams, construction of a stormwater reservoir, and construction of a treatment wetland area. Components work as an overall system to treat stormwater runoff from approximately 1,361 acres to address the water quality problems in the Upper Sandy Creek watershed. This includes approximately 253 acres of total impervious surface (Duke & non-Duke) Reclamation Pond: The total drainage area to the pond is 265 acres and 135 impervious acres. Drainage area represents approximately 22% of total Campus. The overall benefits are as follows: Benefits: Water volume reduction • 1-year storm (64% reduction) • 2-year storm (54% reduction) • 10-year storm (40% reduction) Will act as a stormwater harvesting device Water quality & nutrient reduction (N, P, TSS) Reduced demand on the City’s water system Promotes water conservation efforts Restoring approximately 3000’ linear feet of degraded stream section Educational Benefits: Informational signs will serve as educational tool for the environment