Tender Details
The SCA is currently undertaking a major risk and reliability project for Warragamba dam that includes a review of the reliability of the dam crest gates and all associated equipment involved in their operation. The works will be undertaken as part of Task 13 of the Warragamba Risk and Reliability Project.
The dam has four radial gates and one central drum gate within the crest spillway. There have been recent upgrades to the crest gate systems including work on the electric supply and control systems but most of the mechanical items are still original (circa 1960).
A detailed quantitative Fault Tree Analysis (FTA) including human factors has been undertaken by MWH New Zealand on the gates using the Reliability Workbench V10.2 software supplied by Isograph (Fault Tree+ module). The gates are normally operated during flood events by a REMOTE AUTO mode using a particular H14 protocol. There are however several other backup modes of operation that have varying levels of reliability.
The FTA has included all hazards/issues etc. that are reasonably likely to occur including earthquake, fire, flooding, lightning etc. with specific attention to common cause failures. Due to the age of the dam and restricted access availability in an existing structure, common access systems (e.g. pits, conduits, channels etc.) are an issue.
The results of the FTA identified a few key risks that are the more dominant contributors to the overall level of reliability of the gates. The assessed level of overall reliability for gate operation is deemed to be below that warranted for such an important, critical and extreme consequence category dam.
Location
RFT Type
RFT Preview Document(s)
Additional Details / Instructions
Meeting followed by site visits
10.00am – 12.30pm Tuesday 2nd September 2014
Warragamba Operations Meeting Room
Farnsworth Avenue, Warragamba
(Please meet at boom gate heading down to Warragamba office)
(Site visit will give a general understanding of the crest gates and their operating and control systems)