Allowing contractors to work around-the-clock would cut six months off Renewable Water Resources’ largest-ever underground sewer tunnel project, but it will take a variance from the city’s noise ordinance to put that plan in place.
ReWa Engineer Greg Wright said the city’s noise ordinance allows construction from 7 a.m. to 9 p.m. but nighttime limits are 55 decibels, about the volume of a conversion. But ReWa said the noise could reach 60 decibels, about the volume of an open office or an air conditioning unit 15 feet away. While Wright said ReWa anticipates meeting the noise limitations at all residences, he said a variance will be requested because the anticipated noise level nears allowed levels. While the tunnel boring itself won’t be able to be heard, heard, the train cars that will transport the bored rock out of the tunnel will have to be dumped once an hour. once an hour are dumped. Acoustical barriers could be used during construction to mitigate noise if there are concerns, Wright said.
The $46 million project calls for a 1.3 mile-long tunnel through granite rock 100 feet underground for a new sewer line that will run from Cleveland Park near the Greenville zoo to near Hudson Street.
The project is expected to meet the sewer needs in the Reedy River basin for the next century. The underground tunnel will be 10 feet in diameter and house a 7-foot diameter pipe. Construction is expected to begin in January.
Access shafts will have to be constructed at each end of the tunnel. Rock blasting will occur at each end of the tunnel. The tunnel itself is constructed without blasting by utilizing a tunnel-boring machine that cuts the rock as it moves along the tunnel alignment. Wright said the location of the access shaft at the Hudson Street end of the project had to be moved because of the lack of rock in the area where the shaft was originally planned.
“Normally, finding no rock is good for a construction project. In our case, we need the rock,” he said.
Part of the parking lot off Cleveland Park Drive in Cleveland Park will be used as a construction staging area during the project. ReWa will add parking spots on the Washington Street side of the Cleveland Park playground to make up for the loss of those spaces during construction. After the project is completed, ReWa will restore the parking area used for construction, resulting in 146 additional parking spaces for Cleveland Park/Greenville Zoo.
A community meeting will be held May 2 from 5 p.m. to 7 p.m. at the Kroc Center.