Tuesday, March 8, 2016

Redesign of Springbank Dam may be faulty

Canoeists prepare to run the river below the dam.
The question many are asking in London is: "Should the out-of-operation Springbank Dam be reactivated?" Maybe a better question would be: "How much will it cost to reactivate the Springbank Dam?" I have a gut feeling it could take quite a lot of money.

I was there when the rebuilt dam was first tested back in 2008. Many of those present had serious concerns about the design of the the new gates. Almost all the folk with whom I talked told me, off the record, that bottom-hinged tilting flap gates demand sophisticated engineering to operate reliably. One of the most common problems encountered with this design, I was told, was stream debris interfering with the operation of the submerged hinges. Not just the gates were being tested but the quality of the engineering was also being tested.

I got in touch with the reporter who was with me at the initial test. The reporter confirmed he believed those present thought they would encounter some teething problems bringing the new dam online. That original test was not just some perfunctory operation done to satisfy bureaucratic demands. It was a genuine test conducted to discover the strengths and weaknesses of the new dam design. And, it appears they did discover a weakness -- a weakness that a simple tweak or two was not going to set right.

As most folk know, the initial test of the new dam design had to be aborted when one of the four gates failed. Some blamed stream debris. In mid-summer of 2015 the three remaining gates were retested. Two passed but yet another one failed. Should more money be sunk into repairing a dam which has now failed two tests? Are there serious design flaws at work here?

According to writer Larry Cornies, the new design allows "year-round, dynamic adjustment of water levels in the river." In other words the dam can be fully open, fully closed or anything in between at any time it is felt necessary. Really?

Springbank Dam sits, gates down, out-of-commission.
Based on my talks with those present at the initial test, I believe the present design does not allow frequent adjustment of the position of the gates. Two tests and two failures. This does not inspire confidence. I have read that when operational reliability is paramount there must be a way of clearing debris away from the submerged hinges at the bottom of tilting flap gates.

How much will it cost to correct the faults in the present dam design? Would jets of water or bursts of compressed air clear debris? Possibly filtered river water could be used to flush the hinges before the flaps are raised or lowered. Possibly the design of the gates needs to be altered to modify the water flow pattern as it passes over the hinges.

Restricting the operation of the gates to being lowered in the spring and raised in the fall, as was done in the past, may be necessary. And possibly divers will have to be present to guide the operation and clear debris. Using divers whenever the gates are moved may not be the most elegant solution but it may be the least expensive.

The new dam design may be doomed. I say, remove Springbank Dam. In the past, the river water trapped behind the dam could be damn foul. I used to write the Celebrate the Thames feature for The London Free Press. I can tell you that the river in the area of the Greenway Pollution Control plant was the foulest section of river I encountered during my year and a half of traveling the river from its headwaters to where it discharges into Lake St. Clair.

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