In 2010 Council embarked on undertaking Urban Stormwater Masterplans (USMPs) for key townships within the district to identify the existing stormwater networks in the townships, determine their capacity, and identify options to improve their operation.
The township of Woodside was nominated as the first town to review due to the problems with Main St flooding and inundation of a number of residences in heavier storms.
Council is undertaking further USMPs for Lobethal and Birdwood, both towns with localised flooding issues, and subject to urban development which have placed further pressures on the network.
Information on the USMPs for each township can be found below:
Lobethal Link (to come)
Birdwood Link (to come)
As a general guide, common practice for stormwater designers is to ensure that all storms up to a 1 in 5 year event can be conveyed underground by the pipe network. For larger storms the 'flood' water is intended to be conveyed by the road network or larger creeks. Bear in mind however creeks are NOT controlled or maintained by Council, and are under the management of the Natural Resources Management Board.
They are undertaken using advanced stormwater modelling software and then the results calibrated against observed flooding events in storms (the heavy rains in later 2010 were ideal for calibrating against).
The modelling also provides the ability to consider the impact of development on a catchment, and the effect on the system if large parcels of vacant land are developed into residential blocks. This means Council can then be prepared for future development without adversely affecting current residents.