Edmonton....Construction of a $5-million system, designed to prevent hydrocarbons from the Turner Valley Gas Plant from entering the Sheep River and groundwater, has reached an important milestone.

Concrete pouring and all other weather-sensitive work is complete, meaning the containment and groundwater treatment systems will be ready to go in time for spring run-off, when the risk of contaminants migrating off site is the highest.

"This is a positive step forward and demonstrates that we are well on our way to achieving our clean-up plan," said Denis Ducharme, Minister of Alberta Community Development. "We will continue to work with Alberta Environment, Alberta Infrastructure and Transportation, the health authority and residents to ensure a safe water supply."

The containment system consists of a bentonite (clay) slurry cut-off wall along the bank of the Sheep River and the northern border of the site. The groundwater treatment system is a concrete corridor that captures groundwater and carries it through a three-stage water treatment process. Once the treatment process is complete, the water is safely released back into the Sheep River. The site's erosion protection system features extended riprap bank protection all the way down to bedrock level. The bank height now exceeds water levels experienced in the June 2005 flood, which was the highest flood level in 110 years of recorded history, by at least 0.5 metres.

"We know we have a good design, but it is also crucial that we stay on schedule to be ready for the high-water levels typically experienced in the spring," said Ty Lund, Minister of Alberta Infrastructure and Transportation. "By completing all the weather-dependent work before winter, we ensure the remainder of the work will take place over the winter as planned."

• Containment wall is completed.
• All concrete has been poured.
• Erosion protection work is underway and is scheduled for completion by middle of February. The river isolation was completed August 31.
• Construction of the water treatment facility is underway and on track for completion in March 2007.

Water samples are being collected during any activities that could potentially release hydrocarbons into the river. Soil samples are also being taken, and water samples will be collected and tested for a period of two years after project completion. After that, an evaluation will be carried out to assess the need for further sampling and analysis.

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The Sheep River was diverted away from the gas plant in 2004 to create a buffer zone between the site embankment and the river. Severe flooding during the summer of 2005 destroyed part of the 2004 diversion. Subsequent work in the fall of 2005 re-established the diversion. River isolation work was completed at the end of August 2006 that allowed for the construction of the containment system.

Other contaminants on the site3/4 asbestos, sulphur and mercury3/4 have been removed or contained. This is in accordance with the 10-year clean-up plan, which is being achieved ahead of schedule.

In spring 2006, Alberta-based engineering companies MPE and Stantec designed the consolidated flood prevention/containment system that was approved by Alberta Environment. Quantum Environmental Group is contracted to complete the work, which is being overseen by Stantec and MPE on behalf of the Alberta government.

Stantec designed the containment system; MPE designed the diversion and river protection works. Iron Horse Earthworks was the construction contractor working on the river diversion works.

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Editors Note: For more drawings of the containment and groundwater treatment systems contact Darcy Scott at Alberta Infrastructure and Transportation (780) 422-1173.

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