A National Guard Chinook helicopter Tuesday afternoon moved into position to help patch a flood-breached dike in the Columbia Canal, a job that will include sinking a barge at the gap in the dike then dropping some 700, one-ton sand bags to hold back the Broad River.
But the more crucial repair for the immediate viability of the city’s downtown water treatment plant will be completion of a boulder dam just upstream of the dike, said Columbia utilities director Joey Jaco.
The repairs, needed because of damage caused by historic floods, are being done simultaneously.
“We’ll be working into the night again tonight,” Jaco said Tuesday afternoon of city employees and private contractors who have been laying boulders from nearby Olympia’s Vulcan quarry since Monday night.
By 4:30 Tuesday afternoon, about half the span of the canal had been dammed, said Clint Shealy, the city’s water service superintendent.
The plant, located along the Broad River at Riverwalk Park in downtown Columbia, produces the drinking water for most Capital City residents, about half of the system’s 375,000 customers. Thousands for days have been without water. Everyone else has been dealing with low water pressure and has been advised to boil water because of contamination caused by ruptured waterlines.
The dam is likely to be completed Tuesday, Jaco said. It will create a temporary reservoir to keep water from draining from the canal into the river and allow the plant to continue to operate during repairs, Shealy said.
“This is pretty critical – that temporary dam,” he said. “That will save our water supply. It removes the vulnerability of the breach.”
Adding urgency to Shealy’s remarks about the importance of the dam, Jaco said, “Should we lose this, we would have about a half day to a day of back up at the water plant.”
The water level in the canal held stable all day Tuesday at 7 feet below normal at this time of year, Shealy said. A stable water level is a good sign for the plant. That means workers won’t have to tap the plant’s permanent reservoir or water stored on site.
Meanwhile, city and private contractors are scurrying to patch the dike.
The twin-propeller Chinook made an attempt earlier Tuesday afternoon to lift equipment, including an excavator, needed for the patch, Jaco said. The equipment was too heavy, so some of it had to be dismantled into smaller pieces. The chopper returned later to move the pieces into place, he said.
A 150-foot barge will be steered sideways into the 60-foot dike gash and sunk to the canal bottom, which is about 6 feet deep, the utilities director said. He hoped that would be accomplished before nightfall Tuesday.
Once the barge is in place, a second, smaller military helicopter will lift sandbags that have been piled onto adjacent State Museum property that overlooks the river. Bags filled with rocks will secure the barge and form the base of a makeshift patch. Jaco said most of that work is likely to happen on Wednesday because helicopter pilots are not flying at night.
Electrical lines and other South Carolina Electric & Gas Co. equipment along the canal and river posed safety hazards for pilots. The utility company was diverting power and was downing some lines to make way for the repairs, Jaco and Shealy said. Power poles stand at the upstream edge of where the dike ripped away.
A plug for the dike will allow the city to start permanent repairs, Jaco said. “That will give us the time to do the proper repairs. That (final repair) will probably be a couple of weeks.”
The boulder dam is being constructed upstream of the dike but downstream of the plant.
The stress on the plant’s water supply is occurring at the same time the plant has been pumping 10 million to 20 million more gallons daily to offset water losses because of waterline leaks caused by the weekend’s calamitous rainfall.
There are 15 verified water line leaks contaminating the water supply, Jaco said, adding that at least that many more are likely. “We’ve got a lot of holes in the system (that) we’re filling right now,” he said.
City Hall officials have declined to say how many customers have been without water. But according to Mayor Steve Benjamin’s Twitter page Tuesday morning, there had been 130,000 customers without water. That number later dropped to 42,000, Benjamin wrote at 8:30 a.m.
At about 3 a.m. Monday, the swollen Broad River flowed over the top of the earthen dike, and the dike gave way, Shealy said. The breach was first detected when plant workers noticed a drop in gauges that monitor the canal’s water level, he said.
Plant staff had known for 24 hours that floodwater was causing many water leaks, Shealy said.
Reach LeBlanc at (803) 771-8664.
Boil water advisory safety tips
Yes, your water may be clear. But should you drink it?
No, if you’re a Columbia water customer. Not yet.
Columbia still has not lifted its system-wide boil-water advisory as it works to restore water to 350,000 people in the city and beyond.
So what do you do? Here are some things to know to be safe:
- Even though water may 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