A natural gas operator in Quebec experienced an over-odorization event on a 12-inch transmission line. Liquid odorant had entered the gas stream in volumes beyond what the line could safely carry, pooled at the low point of the pipeline, and saturated the surrounding section with odorant at concentrations far above the operator’s specification. Continuing to operate the line in that condition would have produced widespread false leak calls in downstream communities, exposed the operator to regulatory scrutiny, and risked equipment damage from the high odorant concentrations.
The operator needed the liquid odorant out of the pipeline. That meant locating the pool, accessing it without disrupting the broader system, draining the recovered material into safe containment, and de-odorizing the affected section before it could be returned to normal service. None of those steps could be performed remotely. The work had to come to the pipeline.
Approach
MRR mobilized to the site with the equipment and crews to perform a controlled pipeline drain and de-odorization.
The first task was locating the pool of liquid odorant within the line. Field assessment identified the low point where the liquid had collected. With the location confirmed, the crew excavated the zone to expose the pipe and installed 2-inch taps onto the line at positions selected to provide controlled access to the pooled liquid without compromising the pipe’s integrity.
The recovered odorant was drained from the line through the taps into drums for transport to incineration. The drum-by-drum recovery allowed the crew to track the total volume removed and verify when the pool had been fully drained. Sustained flaring at the site de-odorized the remaining gas in the affected section, bringing concentrations back within the operator’s specification before the line was returned to service.
The work continued for two weeks on site, covering the excavation, tap installation, drain operation, incineration, monitoring, and the restoration work required to close the access points and return the section to operating condition.
Outcome
The liquid odorant was successfully removed from the 12-inch line, the affected section was de-odorized to operator specification, and the pipeline was returned to normal service. The recovered material was transported to a licensed incineration facility. The site was restored, the taps closed, and the operator's section returned to normal monitoring.
The documentation produced through the response — volumes recovered, monitoring data, equipment used, site conditions, and final disposition records — became part of the operator’s incident file. The records support the regulatory follow-up that an over-odorization event of this scale typically generates.
Over-odorization events at transmission scale are not common, but they are exactly the kind of work that requires equipment, crews, and operational discipline that most pipeline contractors do not maintain. The Quebec response was handled end to end by MRR field teams trained for this work.
