Successful first demolition of Large Mining Equipment
The first of the dredger demolition works carried out today (Thursday 15 October) at the Hazelwood Rehabilitation Project proved a success.
Dredger 11 came down a little after 10am with the key objectives of the demolition realised. The main outcome, a safe and successful fell, was achieved with Dredger 11 on the ground.
Watch the demolition video here or below.
All of the blast cutting charges were fully expended with no misfires. A thermal imaging sweep conducted by drone after the controlled collapse showed no issues with hot spots. The immediate geotechnical surveys also showed no issues and batter stability throughout the mine was not compromised.
Post-blast monitoring will continue for a further 24 hours to ensure the overall area has not been impacted for batter stability.
The focus now switches to Dredgers 9 and 10, which will be demolished by the same process next Tuesday (20 October) and the following Tuesday (27 October) respectively.
A review process for Dredger 11 will take place today and tomorrow to assist with preparations for next week’s event. Dredger 25 is planned for December. All dredgers once demolished will be processed and the material recycled.
How many dredgers are being demolished?
There are eight Large Mining Equipment (LME) machines in the Hazelwood Mine area to be demolished, including five bucket wheel dredgers.
Four pieces of LME – Dredger 24, Mobile Slew Conveyor S94, Mobile Slew Conveyor S96 and the TS2 Travelling Stacker – will be demolished by conventional mechanical means.
The remaining four dredgers, 11, 9, 10 and 25, will be blast felled using an engineered controlled collapse due to the height of their superstructures. These four Dredgers are situated in the north-western corner of the mine void and are not visible from outside the mining licence area.
How will they be demolished?
Due to the height of their superstructures, Dredgers 9, 10, 11 and 25 require explosive demolition. They range between 21 to 40 metres high, from 70 to 85 metres long and the heaviest has a service weight of 1,790 tonnes.
Specialised cutting charge explosives will be placed on each machine to cut through steelwork at strategic positions and ensure they collapse safely. A compliant safety exclusion zone will apply for each demolition task.
The controlled felling methodology was selected by ENGIE Hazelwood’s demolition contractor Delta for health and safety reasons, following a detailed options analysis and risk assessment process in consultation with regulatory agencies (WorkSafe, EPA and ERR). The size and design of the four dredgers is such that attempts to demolish by conventional means are potentially dangerous – the explosive cutting charges will enable the weighty, suspended components of the dredgers to be brought to ground in a single event for safe dismantling and removal.
The dredger components will be progressively cut up and removed over a number of months, and the material recycled.
Are there any air quality considerations?
The decommissioned dredgers, as prepared for demolition, contain no asbestos. Any components suspected of containing asbestos were tested, and all asbestos containing material has been removed in preparation for demolition.
The blast will take place in a defined area at the western end of the mine, one of the furthest points from the Morwell township. The works are not expected to have any material impacts on surrounding air quality, however continuous air quality monitoring will occur.
Will demolition be noisy or cause vibrations?
Because of the location of each of the dredgers, significant noise or vibration issues are not expected to arise. The explosions may be audible within surrounding areas, but not at a level that will cause any concern.
As each dredger has been decommissioned it has been relocated to prepared demolition pads. Another damping pad has been installed at each dredger following geotechnical assessments to further reduce any impacts to the batters. No adverse affects are expected, however continual geotechnical monitoring will occur throughout the demolition process.
When will it take place?
The works are scheduled to begin in mid October 2020 and will take place over a number of weeks. The dredgers are scheduled for demolition between mid October and early December, subject to weather conditions.
Once demolished, material will be processed and removed from site over a number of months.
The demolition and clean up process requires manual and mechanical separation. All demolition work is to be undertaken by Delta in accordance with the ENGIE Hazelwood’s approved policies and procedures within the mine licence requirements.
What about any road closures?
No road closures are expected but we are working with Victoria Police and Regional Roads Victoria to ensure all issues are considered.
We will provide advice on the demolition process through a dedicated website www.hazelwoodrehabilitation.com.au as well as via our email database, local media, and direct mail to site neighbours. To join the email database, email email@example.com
ENGIE Hazelwood will seek to hold information sessions, subject to and guided by Government directions relating to COVID-19.
Sizes of the Dredgers requiring blast demolition:
Dredger 9 – 35m high x 85m long x 24m wide. Service weight 1565 Tonnes
Dredger 10 – 40m high x 82m long x 23m wide. Service weight 1790 Tonnes
Dredger 11 – 30m high x 85m long x 31m wide. Service weight 1675 Tonnes
Dredger 25 – 21m high x 70m long x 23m wide. Service weight 1010 Tonnes