Winburndale Dam, 20km east of Bathurst, was originally designed and constructed by the NSW Public Works Department in 1936. The dam has a catchment area of approximately 88km² with a storage capacity of approximately 1,700ML and is currently Bathurst’s second major water storage. Studies indicated that the dam has insufficient flood capacity and consequently flood security upgrade works were proposed to allow the dam to meet modern practice safety standards.

Key project outcomes:

• NSW Public Works providing value to Council and the community by assisting with the securing of grant funding, dam safety assessments, specialist engineering design and advice, end-to-end technical project management.
• NSW Public Works leveraged top talent from across the business to tailor its service offering to the specific job and Council’s requirements.
• Working collaboratively with Council as an ‘extension of their team’ and the head contractor Eodo, a local and second-generation family business who use local sub-contractors.
• Small scale contractor taking on a ‘Tier 1’ job and upskilling its staff in the process on a complex engineering project, enabled by PWA’s technical experience and oversight.
• Collaborative approach to sharing risk through the use of a GC21 contract.
• Strong environmental consideration on the project including a staged tree clearing to allow for relocation of wildlife and posttensioning design instead of concrete buttressing (high carbon footprint).

The main features of the upgrade works are shown on the plan below. The proposed post-tension ground anchors will strengthen the dam wall and effectively stabilises the dam against the updated design flood surcharge loading. The existing 164.8m clear overflow length along the primary and secondary spillways is retained and additional spillway length is not required. The extent of post-tension works provided for the design flood loading is also expected to be more than sufficient to prevent earthquake related failure.