A second collapse of part of the Columbia Canal dike pushed workers to pump Broad River water into the canal Wednesday and prepare to pipe more river water into a reservoir at the water treatment plant, the mayor said late Wednesday night.
Asked if the setback to canal repairs that began Monday raise the chance of shutting down the plant that supplies water to about 188,000 customers, Mayor Steve Benjamin said, "I can't speak to that likelihood."
But Benjamin assured the 375,000 customers in the metropolitan area that the water distribution system will be fixed.
"Day by day, we'll continue to restore service," he said. "But it's a process."
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He said the second collapse this week in the wake of historic flooding over the weekend did not fully breach the dike as did Monday's failure that forged a 60-foot tear. The river has not penetrated at the site of the latest collapse, but it turned the focus of repairs to a third task.
City workers, S.C. National Guard personnel and private contractors have been concentrating on plugging the gash as well as building a temporary boulder dam in the canal that would help raise the water level so that the treatment plant could continue operating.
Workers are trying to strike a balance between slowing the amount and speed of river water in the canal and maintaining a water level that’s sufficient to keep the downtown plant operating for most capital city customers.
Workers were using a diversion spillway at the plant to stem the flow of water so a temporary boulder dam could be completed in the canal, Joey Jaco, Columbia's director of utilities said before the late afternoon work slowdown. Some work continued on placing the boulders. Jaco had hoped the dam would have spanned the canal overnight Tuesday.
Now, their work is compounded by worries over how to repair another weakened section of the earthen dike.
Benjamin said Tuesday that 130,000 were without water at one point, even as city administrators insisted they did not know the number. He said Wednesday evening that fewer than 5,000 did not have water. Still, a boil water advisory remains in effect for all customers but those in the town of Chapin and its vicinity.
“We’re trying to cut the flow in order to work,” Jaco said of the job that began Monday. “We can control the flow rate ... to where it’s manageable. We can’t cut it completely.”
By mid-afternoon Wednesday, the temporary dam spanned about two-thirds of the roughly 125-foot width of the canal.
The dam is intended to create a reservoir that will raise the water level in the canal to a normal depth of 20 feet to 25 feet. The level had dropped to about 7 1/2 feet below normal on Wednesday from the 7 feet below normal earlier in the week, Jaco said.
If the diversion spillway doesn’t do the job, the city has called for as many as six pumps to help slow the flow, Jaco said. “We’re reaching out to everybody we can,” he said.
A request by City Hall on Wednesday for customers to control how much water they use is “an extra conservative effort ... to help us pressurize and replenish the system,” Jaco said.
In addition to the problems at the canal, at least 15 water line leaks have been confirmed, with at least that many more yet to be verified, he said on Tuesday.
Some of the leaks in city water lines -- also caused by floodwaters -- have been repaired, assistant city manager Missy Gentry said Wednesday without disclosing how many.
The plant is pumping 30 million to 35 million gallons daily, he said. City water system supervisor Clint Shealy said Tuesday that is a normal volume for this time of year.
S.C. National Guard troops are to place 750, one-ton sandbags into the gap in the dike. Some sandbags also are being added to the canal’s east bank to control erosion, Jaco said.
It now appears that sinking a barge at the base of the dike will not be necessary, Jaco said. He said he does not know when the dike repair would be completed. The dike gave way before dawn on Monday after the weekend’s soaking by record-setting rain.
Reach LeBlanc at (803) 771-8664.
Columbia calls for water conservation
Water customers were asked Wednesday to minimize their water usage until further notice. A boil water advisory remained in place for all 375,000 water customers in metropolitan Columbia, with the exception of the town of Chapin and surrounding areas, which had their ban lifted Wednesday afternoon.
Here are some things to know to be safe:
▪ Even though water might look clear, it should still be boiled for one full minute before drinking or cooking.
▪ Don’t use any appliances that might require drinkable water, such as ice machines, coffeemakers and drinking fountains.
▪ You can use your dishwasher if it heats the water to 160 degrees Fahrenheit.
▪ Dispose of any ice that might have been made during the boil water advisory.
▪ Turn on taps to flush out water lines.
▪ Water is still safe to use for showering, shaving and other cleaning purposes.
▪ If used to brush teeth, do not swallow the water unless it has been boiled.
Source: City of Columbia