As the people of Greenville populate downtown, history is being made 100 feet below. A very important infrastructure operates out of sight — the sewer system. Even with Dig Greenville, the city’s biggest wastewater conveyance project, ReWa plans to keep it that way.
“Wastewater is the one thing that people really don’t give much of a thought until you flush your toilet and it suddenly, magically disappears,” ReWa CEO Graham Rich says. “I say it’s a miracle every time you flush because it travels a long, long distance.”
Right now, a 6,000-foot tunnel is being constructed underground. The tunnel will house a 7-foot-diameter fiberglass-reinforced carrier pipe to meet future needs. Running from Westfield Street to Cleveland Park, the construction is evident at only two sites and should be completed in 2021.
“Everything that goes right through downtown Greenville is not of impact, and no one will even know we’re constructing down there,” says Stephen O’Connell, Black & Veatch design and construction manager.
The result will be a gravity sewer tunnel, 11 feet in diameter, to accommodate Greenville’s 100-year projected growth. The tunnel will provide greater capacity from downtown into northern Greenville County.
The tunnel will also provide relief of rainwater to prevent sewer overflow into downtown. “We also have a lot of wet weather problems,” O’Connell says. “When it rains heavily, we get a lot of extra water into the existing sewer system.”
Once the 200-foot starter tunnel at Cleveland Park is constructed by hand, the tunnel-boring machine will mechanically excavate the remaining 5,800 feet.
ReWa’s engineering director, Greg Wright, says most tunnels carry wastewater into the ground to be later pumped out for treatment.
“We’re able to drop the wastewater under downtown, still connect it into our system without any pumping, and be able to continue to convey by gravity flow all the way to our treatment facility,” Wright says. “So we have a very low-end operation maintenance and a very sustainable solution.”
Rather than rebuilding the sewer system through downtown Greenville, ReWa chose to leave the existing system active and work underground to add the new pipe.
“Because our pipes run down the Swamp Rabbit Trail, run right beside the waterfall, it would be a very disruptive project to the community as a whole,” Wright says. “Plus, it would add significant environmental risk during construction that we can avoid by doing the tunnel project.”