Tuesday, September 26, 2023

$7.7M project to reduce flooding on New Centre, adjacent problem areas

City to install new infrastructure, improve stream to reduce erosion

A new $7.7 million drainage improvement, to be complete next year, will assist with the chronic, abundant flooding seen on New Centre Drive. (Courtesy/City of Wilmington)

WILMINGTON — A long-awaited project to fix the constant flooding between New Centre and Racine drives, near UNCW, is finally gaining funding and momentum. An area that can see upward of a foot of rain after major storms will be reduced to minimal impact.

Council approved Tuesday a $7.7-million contract to Wilmington-based East Coast Contracting Inc. for drainage improvement along College Acres and stream restoration for Clear Run Branch. Cape Fear Public Utility Authority, the owner of the water and sewer mains, is pitching in $780,000 toward engineering design and construction costs.

The multi-phased project will help alleviate flooding around New Centre Drive when it’s complete. (Courtesy photo)

Mayor Bill Saffo called it the “big enchilada” — the “largest stormwater project done to date.”

“We see the swimming pools every time there’s a hurricane, every national media organization is locked in at Bob King just to share [photos of] the big pool there,” Saffo said at Tuesday’s council meeting.

To tackle New Centre, first the city has to install new infrastructure in the area surrounding UNCW’s campus near the flood-prone road and create permanent drainage easements where there were none prior. The project will begin with Clear Run Branch, which suffers from severe erosion and adds to nuisance flooding, and the undersized drainage system along College Acres Drive. 

“In the past, especially following hurricanes when we could get 5, 6, up to 8 or 10 inches of rain, New Centre Drive and Racine Drive flood and create public hazards and deep water in the streets,” stormwater services manager Fred Royal told Port City Daily. “It also floods apartment complexes in that area; retail centers get flooded.”

Royal iterated this is just the first of two phases before complete flood reduction in that area will happen.

Phase one is set to begin in May, with installation taking place over the course of 12 months. The city will manage the new drainage system in perpetuity. It had to purchase easements in the residential neighborhood to retain full access to what was previously private property. 

The drainage improvement project was initially adopted and funded as part of the city’s fiscal year 2015 capital improvement budget. (The city was also awarded $1.4 million in October 2019 from a National Fish and Wildlife grant to cover the stream restoration portion.)

The seven-year lag time is due to multiple factors: The city had to coordinate and acquire 61 permanent easements from residential property owners, as well as from the state-owned UNCW campus. 

In addition, the aftermath of 2018’s Hurricane Florence shifted the city’s priorities to what Royal called “recovery mode.” Thus many capital projects were put on a back burner.

The global material shortages, supply chain issues and rising construction costs also played a role in its delay.

When construction begins next month, drivers can anticipate delays along Mallard Drive. Royal said the road will be reduced to one lane, limiting complete closure as much as possible, while concrete box culverts are installed. The pipes are designed to fully contain water equivalent to 8 inches of rain over a 24-hour period. 

College Acres will remain open only to residents, so travelers who use it as a bypass will have to find an alternate route.

CFPUA’s portion of the money will fund the replacement of 260 feet of water main and 700 feet of sewer main. In conjunction, 21 residential water service lines will be replaced and a temporary wastewater bypass will be installed to ensure no interruption of wastewater service for customers during construction.

Once all new infrastructure is in place, the roads will be repaved and a 5-foot sidewalk — funded by the city’s bike/ped committee with $76,165 — will be created along College Acres from Racine to Oriole drives.

While the long-term plan is flood reduction, Royal said there is an environmental factor involved. The Clear Run Branch stream, which flows to Bradley Creek — and ultimately the Intracoastal Waterway and the Atlantic Ocean — is unstable. This means the flood waters do not access the natural floodplains. As a result, it gets pooled in deep banks and erodes the land.

A new engineered stream will be created in its place to reduce erosion and grade a new floodplain. According to the city, this project will also improve the water quality, provide wildlife habitat and provide additional floodplain storage by increasing the amount of vegetation. More than 12,000 trees, shrubs, grasses and perennials will replace current vegetation.

Bradley Creek remains a priority project, Royal explained, based on the runoff effect over the last 50 years.

“Stormwater management is to try to slow down and reverse the negative impacts of development on water bodies, which in our case, is the coast,” Royal said.

Phase two, slated to begin next year, will include crews installing large culverts to capture and convey floodwaters under South College Road. This portion will reduce additional runoff into Clear Run Branch.

Royal said he hopes to move into the final design stage for phase two within the next six months.

To further assist with funding, city officials agreed Tuesday to apply for a Golden Leaf Flood Mitigation grant. The state-funded program awards local governments money toward infrastructure projects involving flood mitigation.

The maximum amount to be awarded per project is $250,000, and the city plans to apply for two: One of the College Acres project and one to assist with funding of flood mitigation at Pirate Cove subdivision.

The Pirate Cove drainage improvement plan was adopted and funded in the fiscal year 2020 capital improvement program within the city budget. The neighborhood also experiences frequent flooding during storms.

McGill and Associates was hired in 2020 to complete engineering design to figure out how the system can be improved. While behind on its schedule, the city wants to move into the final design and construction phase. The current estimate for construction is $850,000.

Royal said there are about five more projects like this scheduled for the future.

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