MARCH 2021 INFORMATION BULLETIN
ONE BAD BREAK How a small patch of road slush on a -16 Celsius winter day led to a week of disruption and a $25,000 repair bill.
The Town of Rocky Mountain House maintains 105 kilometres of water and sewer lines. These pipes bring water to your taps and take it away again after you flush. Despite regular maintenance and rehabilitation programs, sometimes a pipe fails. That's what happened in late February at the intersection of 60 St. and Hwy 11A. Doug Fraser, Water/Sewer Supervisor, explains: “It started innocently enough. Someone who knows us phoned in that water was leaking out of the ground. Not much to look at, is it? But it would go on to be one of the more technical, high risk water main repairs we’ve completed. “The problem was the location. A modern town is much like the human body, a maze of vessels, tubes, wires, pipes, and conduits that bring us all the utilities we depend on so much. Extending that analogy, in a very real way, we were doing surgery on the neck of the town."
Anatomy of the break storm sewer watermain Sanitary sewer water at surface
power
watermain break
Telecommunications Fibre optic/ cathodic protection wire old forcemain
forcemain (sanitary sewer)
(Overhead powerlines not pictured) natural gas
“Every type of underground hazard we have in town was present. High voltage power, natural gas, fibre optic, phone lines, and cable. And that’s just the lines owned by other agencies," says Fraser. “Talking about risks for a moment, Town-owned lines in this area are some of the most critical ones we have. Fifty per cent of Town drinking water flows through here as one of the watermains is one of two feeders leaving the plant. Seventy per cent of Town sanitary sewage (that’s just normal sewage to most folks) flows through here. Actually, it flows through twice. First, it arrives by gravity, then we pump it up 60 Street through what’s known as a forcemain. The old main lift station’s forcemain, still serviceable as far as we know, is there too. And finally, there are some major storm sewer lines in the area as well.” On Friday, Feb. 26, the Town ran emergency locates (always call or click before you dig!). Knowing it was going to be a big job, crews were able to isolate the break over the weekend while on-call staff kept an eye on it. Neighbouring residences and traffic wouldn’t have noticed a thing, but for a few locate flags and pylons on the corner.
The operation begins: Monday, March 1 By 8 a.m. the intersection was closed to traffic (and we thank parents on the morning school commute for their patience). Neighbouring residences were placed under a boil water advisory, as per Public Health direction.
“Fortunately, our friends in industry came running, and we had a contract hydrovac on scene shortly,” remembers Fraser. Soon after we found the gas line and could start digging in earnest. Crews chased the water leak to the edge of the locate area, but time was against them.
The first order of business was to daylight the gas line that was immediately near where the water was coming up. “This involves busting the asphalt out of the way, then hydrovacing down through the frost until we get eyes on the line," says Fraser. "Hydrovacing through frost is slow going. Despite getting seven feet deep, we couldn’t find the line." We called in more locates and continued hydrovacing, until the Town’s hydrovac truck suffered a rear-engine failure.
“As we began running out of daylight, we had to shut down. Almost the entire dig both days was directly under overhead power lines. This is hairy enough at the best of times; at night it’s quite dangerous.” Despite darkening skies and tiring crews, they had to bring the hole back to a safe condition for overnight. After 15 hours on the job, they were able to call it a day.
Day 1: digging to the limits of the locate area.
Day 1 ended by filling in the hole for safety
Day 2: Eureka! Monday, March 2 brought more emergency One Calls to expand the dig area. So marked, the first job was to daylight a Telus line in our immediate dig area. With so many underground conflicts we called up two hydrovac units, on top of the frost-ripper and diggers, to get the job done.
Locater marks on the surface - there is a lot going on down below!
There was a lot of iron working on this dig! Many thanks to the contractors.
Here, you can see the watermain all patched up and sporting a silver clamp. The green pipe visible above it is sanitary sewer, and the larger pipes above that are storm sewers. The actual break was located 40 feet away from where the slush first appeared on the road surface. The multitude of lines in the area are to blame. “As best we can tell, the water travelled along the outside of the sanitary sewer pipe, eventually running into the outside of a manhole,” explains Fraser. “Some of it got inside, and the rest pushed its way up to surface.”
“We are very fortunate to have the support we do, to be able to call for this much help when we need it,” said Fraser. “The lines are deep in this area. We were able to bust through the frost with the track hoe, but then from six feet deep down to 16 feet, we had to hydrovac to avoid damaging other lines.”
Found it! Despite best efforts to isolate the break, it was obviously still under pressure!
Here's what all the fuss was about. This pipe was installed in 1972.
Adding up to infrastructure replacement “We suspect the pipe was gouged at some point, and then rust eventually caused a hole,” explains Fraser. “In defense of whoever may have gouged it, in the era before hydrovacs, you had to get very close to the pipe with the digging bucket, sometimes ‘feeling’ your way along it. This is a tricky operation, and there are reasons we try to avoid it these days.” With the clamp in place and the line holding full pressure, crews set to work putting things back in order: filling the hole with dry, well-compacted materials and cleaning up the work area. After 14 hours, the job was done ... almost. Neighbouring residences were still under a boil water advisory. Town staff collected water samples and dispatched them to the provincial lab for testing. The results were back on Friday, March 5, and the advisory was lifted. It's not
$24,428.95 Total external invoices
159 staff hours These costs are in addition to the eventual replacement of the pipe. This is why we have an active underground replacement program! Recent projects include 52 Street between 50 Ave and 53 Ave, as well as 47 Street north of 50th Ave (to be completed this summer). Watermain repairs and deep utility replacement projects are inconvenient for adjacent residents. But, when we replace underground infrastructure it should serve its intended purpose for 100 years. With a little luck, residents won't be bothered by water breaks for another century!
over until everyone is home safe.
Learn more about the Town of Rocky Mountain House infrastructure maintenance and capital replacement plans online: www.rockymtnhouse.com/p/budget
