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Case Study: The Landing at Southpoint Condominiums in Durham, North Carolina

By Boylan Development

The Landing at Southpoint Condominiums

Executive Summary:

The Landing at Southpoint is a new condominium development in the Southpoint Mall area of Southern Durham, North Carolina. In June 2009, The Landing was Certified “Silver” by the U.S. Green Building Council.

The original civil engineering design for phase I called for three large underground sand filters and one wet pond for stormwater quality and quantity control. The cost estimate for the structures in this original design was over $360,000.00 for total materials, labor and equipment. In the value engineering stage, the design team approached the City of Durham with a revised stormwater management plan incorporating the FreeRain System for rainwater harvesting and a constructed wetland. The revised plan was enthusiastically supported by the City of Durham. Ultimately, the team was able to eliminate all three of the large sand filters. By installing the FreeRain System and constructed wetland, the owner saved $200,000.00.

Initial Design Detail:

The original civil engineering design specified three underground sand filters and one wet pond for all stormwater management quality and quantity control. The total estimated cost for all labor, materials and equipment was over $360,000.00.

Revised design with rainwater harvesting
and constructed wetlands detail:

In September 2008, The N.C. Division of Water Quality (DWQ) revised the stormwater regulations to make the use of cisterns for rainwater harvesting more advantageous to the commercial developer and designer. The regulation states that if roof water is collected in a cistern then the engineer can reduce the size of the bio-retention devices on a gallon-for-gallon credit basis. See “Technical Guidance: Stormwater Treatment Credit for Rainwater Harvesting Systems” dated September 22, 2008.

The design team elected to replace most of the expensive underground sand filters with a FreeRain System for rainwater harvesting and a constructed wetland. The developer installed a 22,000 gallon underground FreeRain System for capturing all of the rainwater from the roofs of the two buildings and reusing the water for irrigation and for recharging the constructed wetlands.

FreeRain Cistern InstallationCistern Installation

Stormwater runoff was diverted via swales and sheet flow to the constructed wetland where the suspended solids, nitrogen and other nutrients are filtered, naturally by the soils and plant materials in the constructed wetland. When the water reaches the bottom of the wetland it is pumped back up to the top so that it can cycle through again for continued filtration. By using a cistern and applying for the DWQ stormwater quality credits, the team was able to reduce the volume of the bio-retention areas by 19,100 gallons or 23%.

Wetlands RenderingConstructed Wetland Rendering


By using the FreeRain System in conjunction with a constructed wetland the design team was able to save the client $200,000.00. In addition, since the collected rainwater is being used for all irrigation, the condominium owners will benefit for years to come from reduced water bills. The FreeRain System contributed to valuable LEED credits that helped the The Landing become the largest, privately-funded Leed for Homes certified project in the United States.

Developer’s Project Overview:

“Green Living in the Heart of Durham!” The Landing at Southpoint is the Triangle's smartest and greenest condominium community - 54 luxury flats situated on a one-in-a-million site. Less than 5 minutes from RTP and less than 2 miles from Streets at Southpoint, the community borders a lush federally-protected waterfowl and wetland area. It is an oasis centrally located within the urban fabric Durham, NC.
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Did you know?

7250 Hwy 751 #1102
Durham, NC 27713
(800) 811-3226

Design Team:
Boylan Development
Raleigh, NC
(919) 256-3600

Landscape Architect:
J Davis Architects
Raleigh, NC
(919) 835-1500

Civil Engineering (Stormwater):
EDR Engineering
Raleigh, NC
(919) 301-0990

Rainwater Harvesting Solution: FreeRain
Cary, NC
(919) 460-1180