Intent – To eliminate or minimise the risks of significant environmental harm as a result of the installation and operation of temporary waterway crossings

Critical Controls

  • Ecology professionals are consulted on the structural and hydraulic design for any waterways that have at least intermittent flow and connect with aquatic habitats
  • Temporary crossings are designed to be structurally stable for over-topping flow events, relevant to their anticipated design life and the design rainfall event. This is typically the 1 in 10 year, critical time of concentration rainfall event.
  • Temporary waterway crossings with culverts are designed with a maximum velocity of 0.3 m/s for culverts and with a minimum pipe size of 450mm
  • Temporary waterway crossings are constructed from clean rock >150mm in size
  • The temporary waterway crossing design includes a stabilised overtopping point/emergency spillway
  • Permanent waterways and named intermitted waterways are designed to have maintained the capacity of the existing bank full channel
  • Sediment controls are installed to manage construction runoff from the crossing surface and adjacent exposed areas
  • Approach roads are stabilised (e.g. graveled or trafficable polymer emulsion) and have appropriate flow diversions using cross banks. Cross banks and sediment traps are installed out of the waterway, on highbank floodplain terraces.

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