Over the weekend, Cranbrook Public Works crews went into emergency mode as a number of pipes burst all over the south side of Cranbrook. The bursts happened late Saturday night and into Sunday morning. By Sunday night all but two of the leaks were fixed and by Monday morning they were all patched.
On Wednesday Joe McGowan, director of Public Works, allowed this reporter to sit down with three of the water works crew that helped patch up Cranbrook’s leaking pipes and get residents’ water back up and running as fast as possible. They are Bruce Benson, senior utility operator, Jason Perrault, foreman, and Kent Keiver, lead hand.
At 11:30 p.m. on Saturday night, there was a malfunction at Pressure Reducing Station no. 4. Each Pressure Reducing Station has a pilot control — miniature pressure valves. One of the components failed and caused over pressurization to that zone which caused the eight water main breaks.
“There is a surge relief that doesn’t allow the valve to open up fully,” noted Perrault. “If that failed we’d have been even worse off.”
The pressure reached 20 psi higher than the normal levels. But it was that sudden rush that found the weakest parts of the system at that time.
Pressure Reducing Station 4 usually has a discharge pressure of 54 psi.
McGowan said that water mains are designed to have a normal working pressure of 150 psi, with Perrault adding that they are usually tested at up to three times that.
The first break was recorded at around 3:30 a.m. Benson said there were two personnel out monitoring the leaks as they showed up. As the leaks surfaced, they had to decide whether they would shut them off right away — if they were in danger of flooding the neighbourhood with gushing water — or throttle the pipes down to keep them on until crews got there to fix the leaks.
At around 6:30 a.m. crews started to arrive, including contractors. Benson said they had about 20 workers in total out or headed out by then.
Benson made the calls to locate the gas line, electrical and telephone lines — so crews could work around those lines.
Six of the breaks were fixed on Sunday. The last two breaks were not finished, so on one block crews fed hoses overhead so the houses could have water overnight.
The other leak was throttled down.
“So nobody was without water Sunday overnight,” Benson said. “Then we repaired the two on Monday morning.”
Some of the workers had worked up to 20 hours that day, with most working 16 hours.
The event was a rare occurrence, and they hope it’s not something that will occur again any time soon.
Most of the main lines are between seven to ten feet below the ground, so it took time for the water to make it’s way to the top.
Benson said it isn’t difficult to spot a leak.
“Usually water is pouring down the road like a river for the big ones,” he said. “Little ones people usually say they can hear the noise in the house. The big ones can do a lot of damage in a short amount of time. You get a big two, three, four inch hole, you gotta get to them as quick as you can to try to shut them down.”
They also try to keep a positive pressure on the lines when they are digging a leak, that keeps the mud and dirt from entering into the pipe and contaminating the water.
Benson worked to pull everyone together. He called companies such as Fortis BC to find out where the hydro lines, natural gas and other infrastructure was buried.
They had to bring in five truck drivers and one machine operator.
Kent Keiver was the lead hand out on the field.
Keiver said he prioritized the breaks from most pressing to least.
“Basically we just went from an area that had two or three in one area, so I wasn’t criss-crossing back and forth across town,” he said. “The ones that were out of water of course, we had to deal with them first.”
There were breaks on 5th Avenue South, 3rd Avenue, 2A Street, 9th Street, 20th Avenue, 3rd Street and Brookview Crescent.
Perrault explained why the breaks happened in one specific area of town.
“We have five district metered areas — so pressure zones,” Perrault said, adding that the majority of the breaks happened in one pressure zone. “So you can see in this pressure zone you have PR4 (Pressure Reducing Station 4), which was the problem — that’s the one that over pressurized. Also PR3 feeds that whole zone.”
So when one station over pressurized, the other shut down and all of the flow was going through the one area, he said.
“That’s why they are all contained in this general area, instead of down in the valley, or the college area, or up higher,” he said.
Cranbrook has 13 pressure reducing stations. The station reduce the pressure that builds up as the water moves downhill.
“Water pressure is a function of elevation,” McGowan explained. “At the top of a hill, water pressure is minimal. At the bottom of a hill the pressure is greater, because you calculate pressure based on the weight of the water. The further down you are, the lower elevations of the pressure zones, is the area you would expect to see failures.”