Vapor Extraction Unit Valued In LDC War On Leaks

An experienced gas utility field distribution crew struggled with frozen ground and sub-freezing January temperatures in northern Idaho a few years ago. They were seeking to pinpoint and resolve a natural gas leak in a rural corner of Avista Utilities’ three-state service area. Avista is based in Spokane, WA. The search for the leak was routine, at best, for the crew, but time-consuming.

Today, Bill Baker, gas training and codes coordinator for Avista, looks back with a measure of frustration on that incident that unfolded in a subdivision of five-acre residential properties.

Avista’s crew was attempting to mitigate the leak without knowing its precise source through a traditional hunt-and-peck method of punching a series of holes in the ground and allowing the migrating gas to escape harmlessly into the air.

Flash forward to 2011, and Baker cites the Idaho example as one from the costly, inefficient past. The same crew today relies on a trailer-mounted, mobile, diesel-powered Vapor Extraction Unit (VEU) that sucks up the migrating gas and pinpoints the leak’s source in hours – not days – at about 20% of the cost of the old methodology.

The unit that Baker and his colleagues at Avista now rely on is from M-B-W Inc., a Slinger, WI-based company. The concept for the unit was originally developed by Marc Chapman, director of operations at the Dallas-based Atmos Energy’s Mid-Tex Division. EGASCO LLC eventually patented and licensed the product to M-B-W for design, prototyping and manufacturing.

“It cost about $120,000 to mediate that situation in (northern) Idaho,” Baker said. “If we had had the VEU unit back then, we would have been in there less than five days and it would have cost us less than $20,000. And we would not have had to tear up all the (customers’ yards and then re-do them).”

A vapor extraction unit in use by M-B-W Inc.

Around the nation, other utility operations managers tell similar tales. They began with one VEU and have progressed to multiple units in distribution/transmission operations. Although they either don’t have, or do not want to make public, quantitative data on the equipment’s track record, the utilities are convinced that each unit they employ pays for itself.

“We have not tracked specific quantitative data (on the VEU’s applications, average hours of use/job, estimated cost savings),” said Reid Hess, operations supervisor at Salt Lake City-based Questar. “We do know that it saves us time and money, though.”

Hess emphasized the VEU’s ability to evacuate gas from the ground more quickly than the utility’s conventional method using an air mover. He likes the fact that crews can pull gas from either a broad area or a more compact coverage, varying with the number of hoses that are deployed.

“You may have a small area that gas is being pulled from and you may choose to limit the number of hoses and the area they are being deployed in,” Hess said. “If the area is larger, we may choose to use more hoses and spread the hoses in a larger area to pull gas from the wider space.”

Safety and cost-savings are two big benefits of the units, the utility operating representatives say, and - although none has tried it yet - longer term the units may be helpful in tracking and reporting greenhouse gas (GHG) emissions from natural gas utility operations. A few utilities are at least beginning to think about the VEU’s application here.