A short update on what was a very thorough presentation on Thursday night from the associate director of bridges at CH2M Hill (Halcrow's new name). I can't remember his name and hope I've got his job title correct.
For those who don't already know this is quite a tricky site to work with and has a lot of different parties with an interest in it. The brief from the council is for a 2m wide path with a 1.4m parapet. Which as I'm sure most are aware is wide enough to allow pootling rather than being a full width shared use path, the 1.4m parapet height is a cycling requirement though so good to see it included.
The solution will be designed to cope with a 1 in 200 year flood.
Ideally a light weight solution is required for construction in a very constrained site.
the finished appearance is currently heading towards wooden decking and railings with a steel substructure, similar to the WOL visitor centre.
There were 4 options presented although option D has already been ruled out.
Option A) Build a ramp over the rocky outcrop. This was originally considered to be 1 in 20 but is now designed as 1 in 12 due to space constraints. It is the lowest risk option as no river work is required. It would take 6 months to a year with the path likely to be shut for 6 months of that. the ramp on the north side would be about 180m wrong in an S shape and the steps could remain. The south ramp would be 150m long and the steps would be removed. The total cost would be c.£1.1million.
Option B) A cantilevered structure round the base of the rick. This option would have viewpoints and so easier passing than the ramp. A large chunk of the budget is for rock stabilisation contingency so even though the structure is less than half the length of option A the price remains at c.£900k. Half the length.
Option C) Is to infill the space and esentially use the river bed as support. This would require 300+ tonnes of material which would all need to be prewashed in the work compound to ensure SEPA approval. It uses 15% of width. It is the cheapest option at c.£500k. Although SEPA are currently unconvinced and would only approve if it was shown to be the best option regardless of cost. There is a risk of spending lots on modelling but results being unacceptable to SEPA and others.
Option D) Is 2 footbridges going into and out of Dalmeny. This has already been ruled out due to problems on the Dalmeny bank such as substantial tree clearance requirements and unsuitable paths. The cost would have been c.£1.6million
Other notes:
There is going to be a drop in session at Cramond Kirk in a couple of weeks time (currently scheduled for 5.30-7.30 on the 29th but this may be extended).
I think it was a member of the angling club who alluded to a "plan to reduce flow via a pipeline" but didn't provide details and the presenter was unaware of the plan.
There is a plan for a weir and mill to be removed although this is a separate project and appears to be fisheries related. A few details can be found on google, eg http://www.fishforth.co.uk/rfft/files/2012/04/riveralmond5yearmanagementplanv1_6.pdf
A PDF of the presentation will be made available, I have requested a copy of this.
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