The Big Rocks Weir Business Case has made substantial progress since Townsville Enterprise Limited signed the Grant Deed with the State Government in late October 2019, the Business Case has been funded by the Federal Government through the North Queensland Water Infrastructure Authority. This has been achieved with the assistance of our two major consultants, GHD and KPMG, and the community and stakeholders of the Charters Towers region. This newsletter is an update on the progress of the project since the public meeting was held on 12 February 2020 in Charters Towers. The Australian government has already committed $30 million towards construction of the weir should the final business case show it is viable.
The major milestones that have been achieved:
- Milestone 1 Delivery of the Project Management Plan
- P50 Preliminary Cost Estimate to construct Big Rocks Weir
- Reference Design Bases of Design Report
- P90 Cost Estimate Report
The major works currently being undertaken:
- Water allocation options
- Irrigation/cropping options
- Cost Benefit Analysis
- Draft Business Case Scheduled for 30 June 2020
- Final Business Case Scheduled for 31 July 2020
The following reports are due in December 2020:
- Environmental Impact Statement
- Cultural Heritage management plan
Big Rocks Weir Design Details
The Big Rocks Weir project comprises of four main components:
- Weir and storage area
- Saddle dam
- Access tracks
The objectives of Big Rocks Weir is to establish a new water source that provides additional supply security for irrigated agriculture, improved reliability of town water supply, the potential to support future growth of industry and recreational benefits.
The key statistics of the proposed Big Rocks Weir and impacted storage area are summarised in Table 1 (below) based on the current design progress to date. This data will be refined as the Business Case analyses and reference design progresses. The overall layout for the Weir is shown in the figure below.
Studies to date have not identified any significant adverse geological conditions or potential for additional flood impacts following construction as a result of the proposed development.
Native title, cultural heritage investigations, engagement with adjacent landowners and environmental investigations have commenced for the project.
Table 1. Weir design summary
||An uncontrolled gravity ogee weir constructed using conventional concrete and a saddle dam on the south bank high flow channel, nominally up to 4.4 m high
|Full supply level
||RL 250.9 m AHD approx.
|Storage at full supply level
|Impoundment length (main channel) at full supply level)
|Height above riverbed
||Approx. 13.3 m
||Saddle dam on the right bank 4.4m high and 50.0m long
Access track off the Gregory Development Road leading to Big Rocks for construction and weir maintenance.
Fishway connected to the weir