What Can Chapel Hill Learn from Mecklenburg County About Stormwater Management?

ENVIRONMENT

By Pamir Kiciman

Mecklenburg County is widely respected across North Carolina for its innovations in managing stormwater runoff in urban areas. Tuesday evening, members of Chapel Hill’s Booker Creek Working Group had the opportunity to hear from two Mecklenburg County stormwater experts, who offered ideas for how Chapel Hill can better address its own flooding challenges.

The working group was created in September when the Chapel Hill Town Council withdrew the approval they had previously given to construct six stormwater retention basins in the Booker Creek watershed (Piney Mountain, Red Bud, Daley Road, New Parkside, MLK and Willow Drive).

The withdrawal was a direct result of community activism; once residents became aware that construction of the storage basins would entail clearcutting as much as 50 acres of mature bottomland forest adjacent to residential areas and cost as much as $20 million, they mobilized in opposition to the proposal. After reversing its decision on the storage basins, the Town government appointed a working group comprising community members, advisory board representatives, experts and staff to assist the Town in developing alternative strategies for addressing flooding in the Booker Creek watershed.

In an email, John Morris (co-chair of the working group) explained that the two guest speakers were invited to help the working group carry out the task with which they have been charged, namely, to suggest ways to get the community engaged with efforts to reduce stormwater runoff on their own properties and to propose ideas to help reduce flooding during major storm events.

The first guest speaker was Leslie Vanden Herik, Conservation District Manager for the Mecklenburg Soil and Water Conservation District (MSWCD). According to Morris, Vanden Herik manages a program that uses funds from several different sources to help landowners install projects on their property to improve water quality, reduce erosion and restore natural stream channels. MSWCD provides funding—reimbursing up to 75% of the landowner’s costs— and oversight, while the landowner hires a contractor to do the work and agrees to maintain the projects for at least five years. “We hope that Chapel Hill may be able to develop similar funding sources,” Morris said, “and get projects underway that would help meet two of the Town’s goals for stormwater management: to improve water quality and to restore natural stream channels and riparian habitat.”

According to Herik, the highest priority practice in Mecklenburg County is stream restoration and stabilization. This is achieved by adhering to natural stream channel design principles, such as dimension correction, which entails ensuring that a waterway affords enough space to contain the volume of water it must convey.

Stream stabilization project in Mecklenburg County. Photo courtesy of Mecklenburg County.

Herik mentioned that planting riparian buffers to stabilize waterways, such as planting grass along stream banks, is another common practice that MSWCD funds.

The working group also invited David Kroening of Charlotte-Mecklenburg Storm Water Services to explain his agency’s program to reduce flood damage to structures. Kroening noted that there are ~5000 buildings in the flood plain his agency oversees. According to Morris, Kroening’s agency assigns each building at risk of flood damage a risk priority rating so they can target their assistance where it is most needed. “Charlotte Mecklenburg also uses a greater variety of damage reduction methods than used here,” Morris explained, to identify the most cost-effective method for each at-risk structure. “We [i.e., Chapel Hill] could take more advantage of some of these methods,” he wrote, “such as buying out at-risk properties, flood proofing structures, and elevating or moving at risk buildings.”

According to Kroening, the methodology his agency uses “focuses on assessing risk, deciding how to mitigate that risk, and then prioritizing those mitigation alternatives.” This, in turn, allows the agency “to develop a system through which we can report back to elected officials, report back to the citizens and [explain to them] how their investment is paying dividends to us as a community, through improvement of water quality or reduction of flood risk.”

According to Morris, the working group will next review Chapel Hill’s own stormwater programs so that all group members are familiar with the Town’s current activities. They will then hear from a few more outside experts to be sure that the group has surveyed the best current practices. “At that point,” Morris wrote, “we will have the knowledge base we need to begin to formulate our recommendations. We will work with Town leaders to get feedback as we go along.”