Large Charleston sinkhole not an isolated incident
Last week’s sinkhole on Quarrier Street wasn’t the first the Charleston Sanitary Board has repaired, and it likely won’t be the last, said general manager Larry Roller.
“We’re going to continue to have them because the [sewer] system is in excess of 100 years old, and things that are 100 years old start breaking,” Roller said. “We anticipate and prepare for fixing those kinds of issues.”
It’s unclear what caused the sinkhole, which shut down Quarrier Street between Brooks and Morris streets for parts of two days, Roller said. One lane of Brooks Street was closed, as well. Crews responded to the scene Wednesday evening and discovered a manhole and a storm water pipe that were both in disrepair.
“We couldn’t tell at that stage what had failed first,” Roller said. “It didn’t make any difference. It had to be fixed.”
Crews finished repair of the manhole, pipe and the road, by Friday morning.
The hole, about 6 feet long and 5 feet wide, was small compared to others the sanitary board has encountered. One sinkhole that opened earlier this year at Kanawha Boulevard and Morris Street was 30 feet deep, Roller said. There was another one of significant size at the Boulevard and Greenbrier Street that the sanitary board filled last year. They’re not uncommon on the East End, the oldest part of Charleston, Roller said.
The sanitary board is working on several capital improvement projects that are part of its long term control plan — a 15-year system upgrade meant to reduce sewer overflows that contribute to water pollution.
The sanitary board maintains 300 miles of pipeline, 200 miles of which are combined sewers that transport both sanitary discharges and storm water to the treatment plant. The treatment plant can process a maximum of 28 million gallons of waste and water per day, but typically sees about 21 million gallons per day, Roller said.
Those lines are also designed to overflow into streams when there is a heavy rainfall in the Kanawha Valley, Roller said. One inch of rainfall can bring 1.8 billion gallons into the valley, Roller said.
“Clearly, we can’t handle it,” Roller said.
Because that raw waste and excess water will overflow into streams and eventually the Kanawha River, the sanitary board has been working to upgrade its pipelines since 2008 to reduce Combined Sewer Overflows, Roller said. The improvements comes at a cost. The entire long term control plan was projected to cost $260 million in 2009.
The sanitary board has already completed its $54 million treatment plant upgrade, a $26 million sewer replacement project at Kanawha Two-Mile creek and an $11 million replacement on South Ruffner Road.
Many of the pipes beneath Charleston’s streets are not only aged, but also made of clay. This isn’t bad, and sometimes crews find clay pipes “in perfect condition,” Roller said.
“But, it is 100 years old, especially in the downtown area,” Roller said.
Charleston’s City Council recently approved a measure that would allow the sanitary board to take legal action to secure 16 easements in the Sherwood Forest subdivision for its next sewer upgrade, which will cost about $4 million.
The sanitary board needed to obtain 200 easements for the project that will allow it to work across properties to install pipeline.
Once that project is completed, the sanitary board will replace pipes at Porter Hollow, provided the sanitary board can find the money — about $15 million.
Reach Rachel Molenda