Staff were asked in a recent Council resolution if we could leave the canal damaged pipe “as is”, with the fixes we completed in 2016; re-slope and add cover to the damaged area. We also discussed the expected life expectancy of the pipe repairs and what is involved and costs for an emergency response if more rock fall were to happen and damage the pipe during the irrigation season.
On a Geotechnical and safety stand point
• This area of the mountain is unstable and we may not get sign off from worksafe to have any equipment above the surface (we were cleared to work inside but not cleared outside originally).
• We would likely need another Geotechnical assessment of the stability of the work area and was noted previously that work could not be done during freeze thaw periods.
• T & A rock scaling noted to Geotechnical Engineer that they could continue to chase loose rock 30 to 40 feet north and south of bluff (and further up the mountain) work area and upon a completion of that; bolting would still be required after.
• The Rock Scalers also noted a large block of rock that was separating from rock face for another potential rockfall (picture attached).
• Would Helicopters get close enough to drop (sand) where they need to without being susceptible to any loose materials affecting or damaging their machines from above? Barging material and rock slinging would likely be a more suitable way to cover if we could.
• In 2013 the canal finished a capacity assessment that calculated that the Town could allow 105 to 110 cubic feet per second (cfs) through the canal diversion,
• Staff have determined the canal capacity (operationally) is estimated at 70% (of full capacity) now since working with the temporary fix the last three seasons.