WILMINGTON—If a developer fails to prevent stormwater runoff and their neighbor is flooded with discharge, are they responsible? According to New Hanover County, not always.
A resident near Airlie Road caught stormwater discharge pouring into Airlie Gardens on video during Memorial Day weekend. The runoff came from Airlie at Wrightsville Sound, a State Street Companies development.
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The stormwater runoff was the result of approximately 4.26 inches of rainfall. That was the amount recorded by the National Weather Service in Wilmington. Pools of runoff remained on Airlie Gardens’ property days after rain ended on Monday.
Airlie Gardens is maintained and operated by New Hanover County. According to the county’s engineer, the developer did not breach its permits and will not be paying any fines to cover the overflow event.
Turbid water
When the 11.9-acre development was approved to be rezoned from residential to urban mixed-use on March 7, 2017, its engineering firm claimed overflow stormwater would run beneath Airlie Road.
That’s not what happened on Monday.
Background
At Wilmington City Council’s meeting to approve the development, Council members Paul Lawler and Kevin O’Grady both separately asked the development’s project engineer where stormwater would go in rain events that exceed the county’s minimum stormwater design requirement of 1.5 inches.
“Where would it go if we had above average rain?” O’Grady asked.
Richard Collier, project engineer of McKim & Creed told council members overflow runoff would follow “the natural drainage course” into an existing pipe under Airlie Road.
“It would cross under the road into an existing pipe,” Collier said.
O’Grady questioned, “under the road?” to which Collier responded, “Under the road, yes.”
At the same meeting, O’Grady asked Collier if the existing pipe under Airlie Road was adequately sized for the 11.9-acre project, which has recently been cleared to make way for a 57-lot single-family residential neighborhood.
“My gut would say no, it’s not adequately sized,” Collier said.
Collier currently serves as vice chairman of Wilmington’s Planning Commission, a group that makes recommendations to City Council on whether or not to approve proposed developments. He did not respond to multiple requests for comment.
Even before Memorial Day’s overflow event, State Street was in murky water with its neighbors on Airlie Road. Jeff Kentner, president of State Street Companies, likened the public hearing process during which neighbors were allowed to speak to a “WWF match.”
Listen below: Jeff Kentner, president of State Street Companies, presents to Wilmington City Council March 7, 2017.
No violation
The developer’s land disturbance permit, authorized under the county’s Erosion and Sedimentation Control Ordinance, states “no sediment shall leave the site.”
Jim Iannucci, the county’s engineer, said its erosion and sedimentation control program is designed to prevent sediment from escaping a development project while it is being constructed.
“The goal of that program is to reduce sediment from leaving sites,” Iannucci said.
The ordinance regulates development sites up to 10-year storm events, which translates to “7-inches of rain in 24 hours.”
Despite the National Weather Service measurement, the county found Memorial Day weekend’s rain exceeded the 10-year storm event ratio of approximately “5.5-inch rain event” between Sunday and Monday, the development did not breach its permit.
Robert Digiorgi, a Wilmington NWS meteorologist, said that though his organization’s official measurement for rainfall between Sunday and Monday was 4.26 inches, “rain is highly variable across the area.”
“The rainfall for the month was a record–over 14 inches,” Digiorgi said. “You’re talking about since official records began.”
Official records began in 1871.
With the soil already saturated from rainfall events the weekend prior, Iannucci said excess runoff had nowhere to go but above the road.
As a result, turbid water -“chocolate milk” as Iannucci describes it- pooled into Airlie Gardens property.
After the storm
At the time of the heavy rainfall on Monday, a silt fence had not been installed around the entire perimeter of the State Street Companies’ development. On Tuesday, contractors had installed silt fence.
Iannucci said the installation of additional silt fencing was above what the development is required under the county’s erosion and sedimentation control permit.
“Those measures were in addition to what they were required,” he said.
Still, even if silt fence had been installed along the entire perimeter of the property before the rainfall event on Memorial Day, Iannucci said the overflow may have outweighed the protective mechanism.
“The contractor out there seems to be working with us and is trying to rectify this as best as possible,” Iannucci said. “Typically we’re not going to go right out there and start writing huge fines.”
An absent root system
When soil is disturbed, erosion control becomes a priority. Foilage and root systems are natural mechanisms that prevent excessive stormwater runoff. In their absence, stormwater discharge can be accelerated.
“Sediment and erosion control comes when you disturb the soil,” Iannucci said. “Roots and things of trees, anything that’s going to hold soil, that’s going to help.”
Of the 579 total trees surveyed on the property before it was developed, 120 have already been removed or are slated to be removed, according to the State Street Companies’ tree removal permit. Eighteen of the 120 trees to be mitigated are considered “protected.”
The company plans to plant 163 trees upon project completion to make up for those lost during construction. Once the project is completed, the 57-lot neighborhood will answer to separate regulations under the city’s stormwater division.
“The drainage for this new subdivision is just temporary for now,” the county’s spokesperson, Jessica Loeper, wrote in an email. “Once the development is built, there will be an overflow pipe and it will be piped to a different location away from this low point.”
Though the county did not find State Street Companies to be in violation of its active permits, Iannucci said the Department of Environmental Quality could come to its own conclusion.
According to Tara Duckworth, director of Airlie Gardens, any damage incurred from recent stormwater events will be covered under North Carolina’s Clean Water Management Trust Fund grant.
“Luckily, we have recently been awarded a Clean Water Management Trust Fund Grant to help us initiate our new stormwater master plan that the Airlie Foundation funded,” she wrote in an email.
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