Blasting during construction

Major blasting activities for the Cotter Dam enlargement have now been completed. During the different stages of construction of the new dam blasting was required to attain rock. Wherever possible, mechanical means were used to excavate the rock, but failing this blasting was required.

The Enlarged Cotter Dam Blast Management Plan is the overarching document that outlines roles, responsibilities, procedures and legislative requirements for undertaking blasting activities. The plan is endorsed by the Commissioner, Emergency Services Agency, Territory and Municipal Services, Environmental Protection Authority (EPA), the Manager, Compliance Office of Regulatory Services, and the Department of Justice and Community Services.

Individual blast plans are developed for each and every blast undertaken. Every blast plan is required to be submitted to and approved by ACT WorkCover prior to the blast occurring. As part of ACTEW Corporation’s quality control system for the project, inspection and test plans will be developed by an engineer for the blasting operations, and verification checklists will be signed and dated by the foreman and engineer for each blast. A blast report (including a blast video and monitoring data) is generated for each blast and submitted to ACT WorkCover.

Blasting is monitored at a number of selected compliance points (sensitive receivers) around the perimeter of the blast zone. Monitoring results are collected for dust, noise and vibration and documented in environmental reports issued to the EPA on a weekly basis.

Safety

Three zones of responsibility are established around every blast to mitigate risks and control hazards (see figure 1). The blast zone is a 300m zone around the blast area that is controlled by the shot firer. The exclusion zone is a 700m radius zone around the blast area that is controlled by the construction team. Prior to blasting we will ensure the exclusion zone has been cleared of people. A community zone has been established and represents all sensitive receivers as well as our community interface outside of the exclusion zone.

Community notifications

The size of the community zone has the potential to increase with each blast and current weather conditions. Should blasting be necessary, signage around the area will be updated, and information will be posted to ACTEW’s website. Twenty-four hours prior to a blast, ACTEW will notify the ACT Emergency Services of blasting operations occurring.

Traffic management

To ensure the safety of local traffic all blasts require a Traffic Control Plan to be submitted to Territory and Municipal Services (TAMS) for approval. Traffic stoppage times are minimised as road closures are only in effect immediately prior to and during the blasting operations until the all clear is given (approximately 15-20 minutes). Traffic controllers are used to ensure all vehicles have exited the exclusion zone. Notification to public motorists is provided by signage located at the outer limits of the exclusion zone.