Green Infrastructure

The City of Durham includes green infrastructure and green stormwater infrastructure practices throughout the City by incorporating them into larger city projects, through research projects and grants, partnerships with local organizations, and by working with other city departments.

What is Green Stormwater Infrastructure? Watch this short video to find out!

What is Green Stormwater Infrastructure?
Green Stormwater infrastructure is a type of stormwater management that tries to protect, restore, or mimic the natural water cycle. Green stormwater infrastructure combines elements of the natural environment and traditional stormwater drainage systems to improve water quality and restore ecosystems. Green stormwater infrastructure can refer to behaviors, practices, devices, as well as being a way to design stormwater systems. Green stormwater infrastructure can be promoted through regulations, including guidelines for landscaping that take advantage of ecological benefits provided by natural processes.

Bioretention Cells
One type of Green Stormwater Infrastructure is a bioretention cell. Bioretention cells are excavated areas designed to capture and filter stormwater runoff through specialized soil media and plants. For more technical information, visit the North Carolina Department of Environmental Quality's Minimum Design Criteria and Recommendations for bioretention cells

  • As part of the 2020 Stormwater Infrastructure Repairs (SD-2020-02) project, a bioretention cell is being constructed next to the General Services Department building. Once the project is complete, the bioretention cell will treat stormwater runoff from 0.85 acres of the General Services Department parking lot. This will help to improve water quality in the Ellerbe Creek watershed by reducing pollutants such as nitrogen, phosphorus, bacteria and sediment. Click here to read the August 2020 press release about the project.
  • Recently, the City of Durham partnered with Ellerbe Creek Watershed Association (ECWA) and other contributors to provide funding for the design and construction of two bioretention cells at the Pearl Mill Preserve. The bioretention cells treat stormwater runoff from 1.5 acres of residential area. Visit ECWA's website to learn more about this collaborative project.

Photo of a bioretention cell under constructionA bioretention cell under construction next to the General Services Department building

Duke Park Silva Cell Project
A new type of green stormwater infrastructure device has been installed in the Ellerbe Creek watershed. This winter, a contractor for the Public Works Department installed two Silva Cell  devices along Acadia Street near Duke Park in the Ellerbe Creek watershed. In a Silva Cell, stormwater is retained underground while trees and special filter media remove pollutants. These modular devices are well-suited for urban areas with limited space for larger, traditional stormwater control measures. The Public Works Department worked with staff from General Services and Parks and Recreation to find a suitable location and appropriate trees for these devices. North Carolina State University (NCSU) was awarded a grant from the Clean Water Management Trust Fund to study how well these devices work in Durham's clay soils. In addition to providing the tree with a source of water and nutrients these devices allow tree roots with room to grow. The City worked closely with NCSU and the manufacturer (DeepRoot) to design a system that will fit into the park setting. Researchers from NCSU's Stormwater Engineering Group will monitor and study the devices to understand how they can be used elsewhere in the city. 

Project update | 5/2/2019: What ARE those green boxes at Duke Park? The green boxes contain scientific monitoring equipment that will take samples of the stormwater coming out of the Silva Cells during rain events. NCSU researchers will analyze these samples to see how well these devices 'soak up' pollutants such as nitrogen, phosphorus, and metals. IMG_0488 - Copy

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Project update | 3/19/2019: The trees have been installed! Contractors have been waiting for drier and warmer weather to replace a section of sidewalk. Once completed, NCSU researchers will install monitoring equipment.