Landfill Litter Net Cell, Ebbw Vale
Ward
Jackson Associates was asked by Silent Valley
Waste Services Limited to prepare options for controlling litter
during high winds on its landfill site near Cwm, Ebbw Vale, in South Wales.
The chosen solution was a large contained area of suspended netting, 80 metre long and 26 metre clear span, with an open end towards the prevailing wind direction. Design for wind loadings from the netting onto the supports proved interesting because of the lack any established theory on the subject. The design process resorted to calculating loads on individual lengths of twin an multiplying these loads up to provide netting area loads. Various wind masking factors where considered from other netting panels and a judgement made on the safe factors to apply. Icing loads were also a major consideration in the design.
The off-site works consist of the fabrication of sixteen, 9 metre high, steel masts and supports with concrete block "kentledge" restraints and the manufacture of approximately 3,040 square metres of twine netting of mesh size 85 mm square, together with and extensive system of strengthening and supporting ropes.
A
suitable area of the site was prepared to allow for the handling and connection
of the netting and the ropes without damage and the connection of netting
panels and ropes. The design of the fabricated masts allowed for
relative ease of erection and for subsequent dismantling if the cell when
it needed relocating to keep ahead of the landfill process.
Hoisting of the netting was controlled using the permanent winches fitted
to each mast.
Ward Jackson Associates also acted as Planning Supervisor for the project, administering the health and safety requirements of the Construction (Design and Management) Regulations 1994.
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