South West Rocks Drainage Investigation

A stormwater drainage study identifying existing drainage network deficiencies within the South West Rocks catchment

Storm Consulting were commissioned by Kempsey Shire Council to undertake a stormwater drainage study to identify existing drainage network deficiencies, within the South West Rocks catchment, and to ascertain any future works necessary to appropriately manage stormwater within the township.
The scope of the drainage study included:

  • A hydraulic and hydrological assessment of the existing drainage infrastructure within South West Rocks, assessing the networks capability to manage stormwater during minor and major events.
  • A risk assessment and ranking system prioritising the necessity of future works to the existing stormwater drainage network.
  • Concept plans and cost estimates for any recommended upgrades.

In total the township was delineated in 72 separate sub-catchments which ultimately drain to Trial Bay.
DRAINS was the hydraulic software used for the extensive modelling; this allowed for a suitably detailed assessment of gutter flow depths and velocities, pipe and inlet capacities, and ponding depths at trapped sag points. The analysis of the existing network was based on the criteria in Council’s Stormwater Drainage Specification.
Following the analysis of the existing infrastructure a project specific risk and priority ranking system was developed to ascertain which sub-catchments were most critical and warranted mitigation measures.
Ultimately 3 sub-catchments were identified for future works, with a cost effective and practical solution proposed for each.
The reporting and modelling carried out for this study will form the basis for future drainage works in the township of South West Rocks; with detailed catchment specific investigations to follow.