Sand from the Neuse River is wearing on Smithfield’s water treatment plant.
Sand is entering the plant through the pumps that pull water directly from the Neuse River, said Earl Botkin, director of public utilities. The sand, he said, is corroding the intake pumps before settling in the town’s reservoir.
The sand isn’t harming water quality, but it’s causing damage that will prove costly to fix, Botkin said. The town wants to conduct a study to find a solution, but money for the study is wrapped up in the financial woes of the N.C. Rural Economic Development Center.
The sand problem has surfaced only in the last eight years, Botkin said. “It seems like the dynamics (of the river) have changed,” he said. “There appears to be more sand in the water, and also the river levels seem to be much lower than what they once were.” Botkin said he suspected the additional sand was coming from erosion tied to development.
Water comes into the treatment plant through three intake pumps on the Neuse River, which is the town’s water source. The intake pumps have a grate to keep out large objects, but the fine sand gets through. The water then travels into the reservoir, where it sits until pumped directly into the water-treatment plant. The sand is mostly affecting the intake pumps and the reservoir, Botkin said.
Botkin said an intake pump typically lasts about six years and costs $30,000 to $40,000 to rebuild. The town rebuilt one intake pump two years ago, but it is already showing signs of damage and wear because of the sand, he said.
Sand also builds up around the intake on the river, and the cost of dredging is about $3,500. The town used to perform dredging just once or twice a year, Botkin said, but now it does so four or five times annually.
After coming in from the river, the sand settles in the town’s reservoir, which now has a sandbar of 3,000 to 4,000 cubic yards, Botkin said. That pile of sand is near the pumps that transport water from the reservoir into the treatment plant, which means sand is likely entering the treatment system. Botkin suspects the sand could already be damaging the pipes feeding into the treatment plant.
Earlier this year, the Rural Economic Develop Center agreed to award Smithfield a $30,000 grant to study the problem, with the town providing $32,250. But since a News & Observer investigation exposed misuse of money, the flow of grant dollars has slowed to a trickle as the McCrory administration evaluates each application.
Botkin said he had spoken with Rural Center officials who gave him verbal assurances Smithfield would get the money. But Botkin is waiting to proceed with the study until he has a written promise, he said.
Until then, Botkin will have to be patient. The town doesn’t need to address the problem immediately, he said, but it will have to act soon.
“It’s not a water-quality thing; it’s just a more of an equipment issue,” he said. “The longer it goes, the more wear and tear from the sand on our equipment, and the more it will cost just to maintain status quo with our pumps.”
Chandra Coats, Johnston County’s public utilities director, said sand isn’t affecting the county’s water treatment plant.
The county’s plant is located near Wilson’s Mills, and that area of the river has a different underwater topography, Coats said. She said the underwater topography, called bathymetry,impacts the way the river flows and where the sand is.
“Our intake was put in an area where it’s just not a problem,” she said.
Neuse River and development
Smithfield’s problem is increased sedimentation, said Matthew Starr, who monitors the upper Neuse River for of the Neuse Riverkeeper Foundation. Anything that disturbs soil – including land clearing and construction in fast-growing Johnston – can lead to increased sedimentation as stormwater carries sediment into waterways, he said.
The telltale sign: Stormwater should be clear. “But if it looks like muddy soup, then that’s the fine sedimentation particles in the water,” Starr said. “And when that enters a storm drain or a tributary to the Neuse, it all gets flushed to the Neuse and settles to the bottom.”
“Look at Smithfield 10 years ago,” Starr said. “It’s really grown.”
“But look at what’s happening upstream as well,” he added, citing development not only in Clayton but also in Wake and Durham counties. “All that sedimentation gets funneled to the Neuse, and we send it downstream. It’s directly contributed to the growth (of sedimentation) within the basin.”
Starr said two things can prevent sedimentation. One is vegetative buffers between construction zones and water sources. The other is making sure construction companies follow what are called “best management practices” to keep sediment on construction sites.
Starr said sedimentation is a form of water pollution. “Sedimentation causes a wide variety of issues, from thermal pollution to dissolved oxygen levels to decreased water due to the river filling in,” he said.
Starr said the area’s growth needs to continue responsibly to keep sedimentation from becoming an even bigger problem.