Manitoba Hydro took nearly 2 hours to stop gas leak after pipeline hit by tractor in 2021: safety board

Apipeline rupture inWestmanthat leaked natural gas for almost two hours was theresult of farm activity over shallow ground cover in a field that wasn't spotted by Manitoba Hydro.

That's one of several findings in aTransportation Safety Board of Canada report out Thursday that says the leak occurred on Oct. 5, 2021, after the pipelinewas scraped by a tractor blade ina field in theMcAuley area,near the Manitoba-Saskatchewan border.

No one was injured, but about 84,000 cubic metres of natural gas vented into the air from the Minell Pipeline, which is operated by Manitoba Hydro, over a period of one hour and 46 minutes.

Hydro's own standards aim for a response time of 60 minutes.

The Transportation Safety Board said the amount of soil covering the six-inch (15-centimetre)pipeline had gradually lessened due to agricultural activity. That wasn't noticed inManitoba Hydro damage prevention surveys, the TSB said.

The rupture occurred near TC Energy's Moosomin, Sask., compressor station, which supplies the Minell pipeline, but board investigatorssaid Manitoba Hydro failed to consider asking staff at the Saskatchewan compressor station to shut down the gas supplyon its end.

That resulted in a slower response time, the TSB suggests.

Rules implemented in the U.S. ayear ago require pipeline valves to be shut off within 30 minutes ofa rupture being identified.Canada has no specific response time regulations in place, the TSB said.

Barriers to getting quick help: TSB

The pipeline was hit by a tractor operated by the owner of the land where the leak occurred, the report says.

Both theMinell Pipeline, which wasacquired by Manitoba Hydro in 1999, and a TC Energy pipeline cross that person's land, which he has been aware of since heacquired the property decades ago, the safety board's report said.

After hitting the pipeline, the landowner who didn't have reliable cellphone service at that locationradioed home to tell afamily member what had happened.

Around 3:26 p.m., that family member reported the leak location to a TC Energy emergency number, then called the local volunteer fire department.

TC Energy sent a worker from theMoosomin compressor station. Firefighters also attended.

Roughly half an hour after the call, theTC Energy workerarrived and determined the ruptured line wasn't one of theirs.

The family member then called Manitoba Hydro at about 3:54 p.m., but Hydro was already aware, aftera sensor alarm went off at about 3:18 p.m., warning Hydro's gas system operator (GSO)of pressure and odour irregularities at the site, according to the report.

Hydro sent a technician from Brandon, a 145-kilometre drive away, to investigate.

In the meantime, another pressure alarm went off at a site over 60 kilometres downstream from the leak, at Hydro's gate station inRussell, Man.

Another Hydro technician, from Russell, then travelled toMcAuley and confirmed the leak. Hydro shut the entire Minell Pipeline down at 4:30 p.m.

Forty minutes after that, the technician from Brandon arrived and manually closed pipeline valves at onestation in McAuley and anotherdownstream of the leak site, which stopped the leak, the reportsaid. There was no way to remotely shut down that section of the pipeline.

Line full inspection in 2009

Hydro is required by the Canada Energy Regulator to perform pipeline surveys every 15 years.

Before the 2021 leak, the most recent full inspection of the Minell line was in 2009, though partial surveys were donein 2018 between theTC Energy Moosomin compressor station and the McAuley gate station, according to the safety board. Those surveys didn't detect soil depth issues near the leak site.

After the incident, the Canada Energy Regulator ordered Manitoba Hydro to do a soil depth survey across the entire length of the Minell Pipeline.

Thesurvey found 10 spots with less than 65 centimetres(just over two feet) of soil coverage, including the site of the leak, the report says. Those spots were barricaded off by Hydro and crews notified affected landowners.

Threeof those sites have been remediated and opened back up to landowners, according to Hydro.The other seven will be this year.

The safety board said when the Minell Pipeline was built in 1960, it was required to be buried at least 61 centimetres underground. Investigators determined the blade on the tractor struck the pipeline at only 12 centimetres beneath the surface.

But for several growing seasons the landowner had been removing weeds and silt from the drainage area where the pipeline was buried.

Landowners are generally required to get permission before carrying out activities that disturb the ground, though the safety board's report notes agricultural activity that doesn't go deeper than 30 centimetresdoesn't typically need authorization.

The landowner assumed he was in the clear because the weed and silt removal was something he had been doing in the area for years without Hydro telling him to stop, the report said.

The safety boardalso sent a letter to Hydro in early 2022 reminding the Crown corporation thatoperators need to keep tabs on soil cover depth over their pipelines "to ensure they are adequately protected against normal agricultural activities."

Hydro has met with landowners and "committed to taking the steps necessary to prevent such occurrences from happening in the future," a spokesperson said in a statement.

Hydro also recommends lawndowners alwayssubmit requests throughits website before doing any excavation work.