Project Overview

Person Street is a major route into downtown Fayetteville, North Carolina. In 2016, the city and North Carolina State University set out to make two blocks of that corridor greener, more welcoming to pedestrians, and better equipped to manage runoff before it reached nearby Blounts Creek. The redesign narrowed the roadway, added planted bump-outs and permeable parking areas, and reduced impervious surface by approximately 30%. These changes also created a more defined, calmer streetscape.

The stormwater strategy extended below ground. Silva Cells were installed beneath paved areas to hold planting soil for four street trees while adding bioretention capacity where there was little room for more planting at the surface. Together, the visible landscape and the underground tree systems allow Person Street to slow, absorb, and filter runoff close to where it falls.

How Silva Cells Manage Stormwater on Person Street

The planted bump-outs are the most visible part of Person Street’s stormwater system: runoff enters these landscaped areas and filters through soil. Silva Cells bring a similar process beneath the paved street. At the Silva Cell tree planters, curb openings admit runoff from the gutter, while rain can also pass through adjacent permeable pavers. Beneath the pavement, distribution pipes and planting soil spread and filter the water through the tree root zone. Across both sides of the street, a total of 130 (2x) Silva Cells create two connected soil areas, each shared by two trees. Each tree has access to nearly 900 cubic feet of shared soil, which serves as both root space and underground bioretention media. The combined green street features were designed with a goal of managing approximately 85% of rainfall on this section of Person Street.

• Capture: Curb openings and permeable paving bring water into the tree planting areas.
• Bioretention: Soil within the Silva Cells temporarily holds and filters water around the roots.
• Controlled Release: Underdrains and overflow connections provide a route to the storm system when water remains after treatment.

Monitored Success

NC State monitored the green street’s stormwater performance, completing its work in spring 2020 and delivering a final report to the city later that year. Fayetteville has described the completed project’s combination of bump-outs, Silva Cells, and permeable pavement as meeting its runoff volume and water quality objectives. In a subsequent city statement, it reported that the green street reduced the volume of stormwater entering Blounts Creek during normal rainfall. Silva Cells supplied underground soil and bioretention capacity alongside the project’s surface features, helping the city make stormwater management a function of the street itself.

Healthy Streetscape Trees

Person Street’s trees make that working landscape visible. Silva Cells give the four tree planters access to soil beneath surrounding pavement, where roots can grow and use some of the water the system captures. Water that remains can move through the underdrain rather than relying on the small tree openings alone to hold it. The city has continued to care for the greenscape, including refreshing plantings and maintaining the permeable pavers. Today, established trees and planted bump-outs help define a greener entrance to downtown — while the soil and stormwater infrastructure continue their work largely out of sight.