Province's 'tiger dams' found wanting

What is worse than having no flood protection when you need it? Reliance on flood measures that fail. The damage is as bad and your belief is shattered. In addition, all the costs and efforts to build the emergency dam are wasted. Thus, the efficacy and costs of alternative flood protection systems are important topics to consider as a new flood season looms.

In the last few years, a new system of water-filled orange tubes, called tiger dams, has appeared on the Manitoba scene.

The tiger dams are promoted as a stackable system, but they offer much less protection than homeowners may believe, unless that is, they remember pictures from the Winnipeg Free Press of these orange tubes with water lying on both sides.

A recent University of Manitoba engineering thesis compares four alternative means of temporary flood mitigation. The results are disturbing. The study assesses traditional sandbag dikes, tiger dams, aqua dams and TYPAR matrix in terms of stability, constructability, safety and cost.

The tiger dams are the least reliable system and most likely to slide when the water comes. If arranged in a stacked configuration, the orange tubes are neither stable nor safe, and pose the least resistance to flood waters.

The orange tubes are less expensive to deploy than sandbag dikes, but if they do not work, the price is irrelevant.

The problem begins with the specific site requirements of the tiger dams. Sharp objects, vegetation, snow, ice, and other structures must be removed from the ground. The tubes are susceptible to puncture by sharp objects, floating ice and debris.

Moreover, the ground cannot be porous. If placed on gravel, the water will seep underneath and cause the tube to become buoyant. If stacked in a pyramid formation, additional chocks and straps are required.

Currently, there is not an engineering design for the stakes or the placement of the straps and stakes. In response to this fact, the tubes cannot be considered safe in a stacked formation.

The lack of engineering design for the tiger dams reflects the weak research support for this technology. Setting up tubes in a flooded enclosure with a smooth concrete floor and no current or wave action does not constitute rigorous testing.

The company product-testing report supplied by the Hon. Steve Ashton, then minister responsible for emergency preparedness, would not qualify for an elementary school science project.

Based on this minimal research, millions of dollars were spent in the midst of an emergency on these orange tubes. Without putting too fine a point on the experience, it has all the hallmarks of danger opportunism.

International Flood Control (IFC), the company selling these orange tubes, is presenting an evening with former governor of California Arnold Schwarzenegger in Winnipeg next week.

As much as the community may appreciate IFC bringing Mr. Schwarzenegger to speak, the public might wonder why any more would be spent on unreliable flood protection.

Winnipeggers should take note of the flood that has been happening in Queensland, Australia.

We may have been lulled into a sense of complacency that the recently completed floodway expansion will save us from a 700-year flood.

Historically this is surely true. Looking forward, the claim is more uncertain. Climate change is predicted to result in more dramatic weather extremes in the next 100 years.

A record flood in Pakistan, a record flood in Queensland -- maybe these are the harbingers of the Red River flood in store for this spring.

The government of Manitoba can be given credit for identifying the flood risk early, and for taking proactive steps, like the recent delivery of another Amphibex floating backhoe.

Where more work needs to be done by the government is to scientifically test the efficacy of the orange tubes before any more are acquired or deployed.

No one wants to surround his or her home with a flood-control measure that is likely to fail. The ground preparation required for the orange tubes is excessive and impractical in an emergency situation when the ground is frozen and equipment is scarce. Until IFC can prove their tiger-dam technology can meet independent engineering tests, they should be barred from trying to pull the "orange wool" over an unsuspecting public's eyes.

Barry Prentice is a professor of supply chain management at the University of Manitoba.

Republished from the Winnipeg Free Press print edition January 19, 2011 A10