Matthew Lambourne, Mullumbimby
It’s hard to satisfy Jim Mangleson, isn’t it? In my original letter on 19 September I pointed out that Council asked the developers to restore road access at the outlet site, but did not ask or order them to close the outlet. In his reply (Letters, 26 Sept) Jim agreed that ‘Council requested the developers to restore the sand-mining road’.
Now Jim again claims that Council ‘requested the developers block the outlet’ (Letters, 10 Oct) and claims that ‘Council documents’ support this claim. They don’t – I challenge Jim to produce a Council document that supports this claim.
Jim then suggests that the modelling of the flood outlet showed little benefit because they modelled it ‘without the original connection of the old Billinudgel Creek’. The only connection between the outlet and Billinudgel Creek, which is in Tweed Shire at Wooyung, is about 2.5km of wetlands, which were included in the model.
More relevantly, the modelling included ‘a hydraulically efficient link between the existing drainage system and the outlet’ (Notes to Accompany Flood Outlet Runs – June 1995). Basically, this would mean something approaching the size of the Capricornia Canal extending from the canal to the outlet to allow a free flow of floodwater, and reduces the flood level at the canal by 69mm in a 1-in-100-year flood, as I wrote in my letter of 3 October.
Jim then claims that when the outlet was ‘remodelled with the connection’ there was a reduction of 354mm at South Ocean Shores. No so. The result Jim is referring to is in an attachment to a letter from the then Shire engineer Greg Alderson dated 25 June 1991, and is for the 1987 flood with the flood outlet, the connecting channel, and the dredging of Marshalls Creek. The dredging is claimed to reduce flood levels at South Ocean Shores by 322mm, and adding the flood outlet and channel contributes a whole extra 32mm to make up Jim’s 354mm.
In the past Jim has wanted the rock walls at Readings Bay removed, but now it seems he thinks the ‘Council had better shut the big opening at Brunswick Heads called the Brunswick River’ (Letters, 10 October). I’m not sure that would work at Bruns, but according to the mayor at one of the meetings after last year’s flood, the flood modelling showed that completely blocking the Belongil entrance would reduce design flood levels in Byron Bay.