State throws wrench in Chapel Hill rules for stormwater runoff in Blue Hill

Heavy storms can swamp retail sales floors and parking lots with polluted floodwater in just minutes at Eastgate Crossing, Mariakakis Plaza and other shopping centers east of downtown.

In September, the remnants of Hurricane Florence dumped 6 inches of rain, pushing floodwaters several feet high, swallowing parked cars, and forcing emergency crews to rescue 40 people from the muddy water.

The heart of Chapel Hill’s Blue Hill redevelopment district was built when developers didn’t worry about runoff or pollution. A form-based code was applied to the district in 2014 to encourage redevelopment of single-story strip malls and, in part, to start addressing longtime stormwater problems.

The town applies some of its toughest rules to the district, requiring developers to capture and filter runoff from at least half of the new and pre-existing rooftops and other impervious surfaces. Typical measures can include ponds that capture and slowly release water, rain gardens, and underground detention and filtration systems.

Developers also must leave a 50-foot, state-mandated vegetative buffer around creeks and streams.

In December, the state legislature voted to limit local stormwater requirements for redevelopment projects. Now, developers only have to treat stormwater running off any new impervious surfaces. That doesn’t offer much help in the Blue Hill District, where roughly 57% of the land is already impervious, and redevelopment is only expected to increase that to 60% to 70% over the next 20 years.

The legislature is “basically taking away our municipal power to remediate stormwater, so right now, we’re really just trying to do something quickly and easily that’s not going to [require] a huge public input process, that is not going to be a difficult process,” Mayor Pro Tem Jessica Anderson said recently. “We’re really just trying to make it so that people can’t do less than we want them to do on stormwater.”

An attempt Tuesday to reach state Sen. Harry Brown, the Republican Senate majority leader who sponsored the law, was unsuccessful.

Stormwater incentive

The town’s proposed incentive would reward Blue Hill developers with taller, denser projects and higher profit margins if they treat more stormwater than the state requires. It does not let developers build more than already was allowed under the town’s rules.

Developers who choose not to meet the town’s stricter but now voluntary requirements would face limits on building height and density. They also would have to meet the town’s Resource Conservation District rules, which require a 150-foot buffer around streams and creeks, and would face a longer review than the form-based code’s typical months-long approval process.

Under the code, Blue Hill projects only require Community Design Commission and town manager approval. Projects elsewhere in town face at least a year or two of public hearings, advisory boards and council reviews before a decision is made.

All buildings still would have to be at least two stories tall and dedicate at least 10 percent of available space to commercial uses.

The council will hold a public hearing and could vote on the incentive June 26.

Blue Hill stormwater changes.jpg
A proposed change to the stormwater requirements for Chapel Hill’s Blue Hill District would allow developers to build more dense, tall projects if they choose to voluntarily treat 50% of the new and existing runoff. Projects that only meet the state’s requirement to treat new runoff would be limited. Town of Chapel Hill Contributed

Developers who follow the conventional path could lose as much as 80 percent of their potential square footage — and corresponding profits — compared to those who meet the town’s Blue Hill stormwater rules, planner Corey Liles said.

“With that conventional path, we know that there’s going to be lower buildings and a smaller amount of buildable area, so we would expect it’d probably be some single-use commercial and residential buildings with enough leftover area to do surface parking,” he said.

Developers have said they would likely follow the town’s rules on a site with a stream buffer because they would have more space to build on, he added. That’s critical, because redevelopment and commercial growth are helping to pay the cost of fixing decades of poor stormwater and traffic planning.

Other options could come to the council in the future, include requiring projects to have more green space to filter runoff, promoting projects with a low environmental impact, and incentivizing the capture and reuse of rainwater.

Town staff also is looking for ways to spur more affordable housing, green spaces and environmentally sustainable projects. Anderson noted that the council also will talk in the future about the “massing” of buildings, or how much space they occupy on a site.

Some of the bigger Blue Hill projects — like the roughly three-acre projects, Berkshire Chapel Hill and Fordham Boulevard Apartments — have been criticized for their height and for covering nearly all of the available land. The town also has been criticized for allowing Ram Realty to build the Fordham Boulevard project roughly 50 feet from the banks of Booker Creek.

The developer is working with town staff on a $1.1 million expansion of a four-acre Booker Creek gully between the development, Eastgate Crossing and the Village Plaza shops on South Elliott Road. Construction on a bigger detention pond could start this summer.

Related stories from Raleigh News & Observer

Tammy Grubb has written about Orange County’s politics, people and government since 2010. She is a UNC-Chapel Hill alumna and has lived and worked in the Triangle for over 25 years.