Dear Editor:
The City installed a liner in the main water tank last year (2009) and according to Brian Mallet (Director of Engineering for the City), it should be good for about 5 years. I understand that it cost +/- $115,000. My question to council is , why are we replacing the tank this year?
The article (Times Review dated Dec.22/10) stated that Dayton & Knight didn’t know about replacing the valve house and related piping is very hard to swallow. Dayton & Knight has been 100 % involved from 1995 – 1996 onward. They have written more reports on this valve house, designed and overseen the implementation of the altitude value, the increased pressures on the lines, etc.
From the valve house back to the east is the most vulnerable piece of our main system. The valves no longer shut off completely ,but the bigger problem is the A&B lines running from the valve house back to the East end of Upper Alpine Lane. These lines were installed in 1961. The pipe itself has no problem with the increased pressures being placed on them, but the joints do. When this was originally installed, the tank was designed to fill and then continuously overflow. The pressure on A & B was minimal, maybe 20 – 30 psi when open. With the installation of the Treatment Plant, we could no longer overflow due to the chlorine content of the water. This is when the altitude valve was installed (designed and tested by Dayton & Knight). At this time the pressures on A & B increased to +/- 100 – 120 psi when the tank was not filling. This is when the problems started. In the last 3 – 4 years of myself working there (end of 2006), my co-workers and I fixed approximately 6 – 8 leaks, which only became evident when they worked their way to the surface of the ground. Each one was identical. The 0-ring seals at the joints where flattened at a spot, perhaps by being forced together with not enough lubrication. These start to leak because of the increased pressure. AC pipe, by design, is vulnerable to cutting by the water under pressure leaking out – over time these became big enough that I could place my hand on it’s side into the cut. Needless to say, the leaks where significant in nature. A & B lines are directly above the area of Clearview Heights that slid in the late 1950’s, due to excessive water saturation in the ground caused during the TCH construction.The MOTH has the lawsuit on file. A&B lines are approx. 1 km long, the pipes are 4m in length totaling approximately 500 joints. The pipe is buried anywhere from +/- .75m to 4 m deep due to the lay of the land. There is no way to check if these are leaking because the valves in the lines are so badly barnacled that they do not seal at all, so no way to pressure test.
There is no way to determine if any or how many joints are leaking unless they come to the surface of the ground. With the history of Clearview Heights Slide and the number of leaks already found, these lines become very critical in terms of possible leakage already occurring or that may occur.
It is my understanding that a Senior Staff decision to increase the pressure from Greeley during high flow demands to ensure Hillcrest has sufficient pressure, only compounds the strain on A & B lines. (Hillcrest has been repeatedly told to install a pressure pump on the their own line as there has always been water available, just no pressure).
In closing the line from the KOA Junction to A & B is a single 14” line that also needs to be upsized as well. By putting a liner in the water tank in 2009, this has bought some valuable time in which to replace the valve house and at least A & B lines. To replace the tank this year is a waste of the +/- $115,000 spent on the liner and leaves the area below A & B lines in an increasing level of potential jeopardy if they are left to some future point.
Based on Brian Mallet’s math, if Dayton & Knight’s detailed estimate was $1,550,000 as stated, and the reduced cost for the tank is $1,400,000, it therefore would be logical to assume the cost of the valve house is $150,000. Given these facts, then coupled with the Building Canada Fund of $644,000 plus the $322,000 from the City of Revelstoke, it is very feasible to conclude that the value house and A & B lines and possibly a segment of the 14” line could be completed under this grant. That would save us a need to borrow an additional $600,000 for the tank alone and the $115,000 spent on the liner is not wasted by doing the tank now.
Bob Melnyk
Revelstoke
