Low flow caused sewage woe

By Collin Gallant on July 21, 2018.

cgallant@medicinehatnews.com @CollinGallant

Current work on sewer lines under Carry Drive is, at least in part, a lingering result of failed real estate development on the other end of town, the News has learned.

Utility officials confirm a $4.5-million repair project, now underway, is needed due to the type of piping used in an expansion 14 years ago, along with less than expected sewage.

That volume would have arrived via a cross-town connection to the failed Cimmaron development in the city’s southwest.

The resulting lack of flow caused buildups of corrosive gas that pitted the particular type of pipe used in the Carry Drive sewers from Scholten Hill to Southview Drive.

“The deterioration … is the result of the combination of the particular piping material and the low-flow environment within that specific line segment,” Brian Murphy, the general manager of the environmental utilities department, tells the News.

“Because much of this development has not occurred as originally anticipated, flows in the Carry Drive line segment are lower than the design flow rates.”

The circumstances were alluded to but not fully explained this spring when council approved a $4.5-million tender to coat the lines beneath the busy roadway this summer.

Council members wondered at the time why the work was required so soon after the $6-million line replacement was done in 2004.

Most newer south-end communities are now complete, and the entire area had boomed since the early 2000s.

The 2004 upgrade was done to extend lines to the new community of Southlands, south of the Trans-Canada Highway, and a larger than required pipe was installed along Carry Drive to handle expected volumes from Cimmaron, as well as long-standing plans for housing in the Holsom Road area.

Plans for the Cimmaron community, west of south Boundary Road, haven’t gone ahead since its two subsequent owners declared bankruptcy.

Such “upsizing” of utility projects is common in city planning, and is typically a good way to avoid cost and construction, as development occurs over time and more capacity is required.

In sewers however, larger pipe diameter results in lower flow rate, and without more sewage, the longer frame allows hydrogen sulfide gas to build up with damaging effects.

The current work will see the inside wall of the Carry Drive pipes coated to fill pits, reinforce the structure and guard against similar erosion in the future, said Murphy.

Coating the pipe is “significantly” less expensive than full repair, and because the specific piping was localized, pitting shouldn’t be a problem elsewhere in the system, he said Murphy.

The $4.5-million project was awarded in April to Instiform Technologies. Some general excavation work is being conducted by MJB Entrerprises, but the process doesn’t require the length of the pipe to be exposed, thereby saving the roadway.

In 2009, Medican announced a 20-year plan to build housing and commercial developments on about 870 acres of farmland near South Boundary Road.

But, the Cimmaron plan was sold in 2010 before the company entered receivership. The buyer, the Foundation Group of Companies, collapsed amid fraud allegations in 2013.

Recent city planning department outlooks state they expect no development in the area in the medium term, until at least 2025 or later.

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