Toowoomba Regional Council (TRC) has received a key development approval for the Cressbrook Dam Safety Improvement Project (CDSIP).
TRC Mayor Geoff McDonald said the ERA16 approval was granted by the Queensland Government's State Assessment Referral Agency.
"This approval allows us to reuse materials removed for widening the spillway and deepening the plunge pool on other parts of construction.
"The TRC CDSIP team and our Alliance partners have successfully negotiated this approval which serves two main purposes, it provides a significant part of the project's path to construction and works to protect the local surroundings.
"Achieving this approval is critical in securing the authority to start construction. The application process required months of careful planning and consideration. Receiving this is a significant milestone for the teams involved," Mayor McDonald said.
"There's an extensive amount of technical review required in a project like this. We're assessing the new safety guidelines and integrating important data to future-proof the dam. As we do this, we're being guided by our engineers, the Cressbrook design team, and an independent panel of experts," Mayor McDonald said.
The CDSIP has been mandated under the Queensland Government's Water Supply (Safety and Reliability) Act 2008.
Deputy Mayor and spokesperson for Strategic Water Planning and Capital portfolio Councillor Rebecca Vonhoff said designing safety improvements for a dam built over 40 years ago is a detailed process.
"We're carefully analysing different data sets to ensure we design for the long-term. Data being analysed includes climate, hydrology, the dam's location, and geology.
"A detailed understanding of how the Cressbrook catchment responds to storm events is also needed.
"The dam's specific location also adds to the complexity of the design process, particularly in terms of hydrology. Cressbrook Dam sits below Council's Perseverance Dam, and we need to carefully consider how these dams impact one another during different weather events.
"The Cressbrook team is also reviewing the original as-built dam records to ensure they know what to expect on site once construction starts. They've spoken to engineers involved in the original construction to verify early geological testing and confirm what they've seen in historic construction photos.
"We need to understand what our findings are telling us about what actually took place during construction in the 1980s. Knowing where specific soil types are located on the crest significantly informs our next design decisions," Cr Vonhoff said.
TRC has also recently reached an agreement with Seqwater to store water that's released from Cressbrook Dam in Wivenhoe Dam.
