Greenville is receiving the largest green infrastructure loan in state history to help fund the replacement of a roughly 90-year-old culvert in the heart of the city's Uptown district.
Construction on the Town Creek Culvert Project is set to begin early next year after the Greenville City Council unanimously approved a $22 million contract with Trader Construction Company in New Bern last Thursday. Because the project includes green infrastructure that will absorb and clean the storm water, the city has received a $16.3 million interest-free loan from the state's Clean Water Revolving Fund.
Porous pavers will reduce the amount of rain water that drains into the culvert, but the major piece of green infrastructure is a regenerative stormwater conveyance system, which will improve water quality as the storm water moves through a series of step pools, said Kevin Mulligan, the city's public works director. After the storm water flows through the new underground pipes, it will enter a green valley across from East Carolina University, where layers of sand and stone will remove nitrogen and phosphorus from the water before it reaches the Tar River, he explained.
The system will look like a scene in nature situated in an urban environment, Mulligan said. "If you were hiking in a mountainous area and you saw a stream coming down a mountain, it levels out at a point and then drops down. And those areas where it's dropping down, that's those step pools," he said.
He describes the project as "fiscally responsible" because the interest free state loan will save the city $7 million, Mulligan said. The new 84-inch concrete pipes are designed to withstand 25 year storms, which amounts to about eight inches of rainfall within 24 hours. By comparison, the current pipes can only handle drainage from two year storms. The entire project will take about two and a half years to complete after construction begins.