Handheld hydraulics in aboriginal arts protection
2009-08-28
Aboriginal artefacts on heritage listed rock and a mine with economical interests have been the basis for an unusual and technically difficult job carried out in Werris Creek Mine, Australia. Handheld hydraulic products from Atlas Copco have been the key to carry out this sensitive job successfully.
The heritage listed artefacts are cut out carefully
The open cast operation is located on property that extends over 1500 acres in hilly countryside, 80 km inland from Tamworth. Aboriginal artefacts had been found in the mine area already in the early 1900´s. On the top of a hill nine locations of rock holding rubbing grooves had been identified as aboriginal artefacts as well. Five of them have been firmly attached to the conglomerate rock forming the hill, four of them laid loose on the ground.
A considerable volume of coal was lying under this hill. Atlas Copco was asked to find a method to remove them without damage and store them in a safe place, until they could be placed back in their original locations after renaturation of the area.
Since land development in classified heritage listed areas is generally prohibited, a potential cultural conflict was to be prevented. Negotiations were difficult, but at the end an agreement was reached between Mine Management, an Archaeologist appointed to the project and four aboriginal tribes who had links to the site.
Under very strict controls, permission was given to undertake the project, supervised by an archaeologist with an Aboriginal tribal elder present to ensure adherence to their religious and cultural needs.
Mopieka Holdings Pty. Ltd., owned by Bruce Garland, the contractor of this job, decided to use the following Atlas Copco equipment:
- LP 18 Twin PE power pack, used to power the following
- LCD 15 Core Drill, for drilling core holes and creating stress lines
- LWP 2 Water pump, for pumping water from a dam into tanks on a trailer
- LS16 Cut-off saw, for cutting stress lines and isolating smaller rocks
- LH23M rock drill, back up in case water became an issue.
The floating artefacts have been removed first by using high pressure water to clear away roots and subsoil. In a next step Bruce Garland and his team excavated round the rocks with firm connection to the bedrock. The rocks had to be lifted in such a way, that natural flaws in the rock could not be stressed, resulting in a break and create a heritage and cultural disaster.
Once the rock had been excavated around to a sufficient depth, Garland´s team stitched a series of 48mm holes along a line that would create a break line when the splitters are activated. The holes are going through the rock after it had been split, this is where the operators placed the lifting steels of 50 mm rebar. Extension rods were used on the LCD 15 core drill with a 48x450 mm core bit to go through the 1.4 m width of rock.
Once the lifting rods were in place, a mobile crane lifted the rock onto a truck with a bed of loose stone chips on it to protect the rock during transportation.
The working conditions have been tough: the temperature was in the mid 40 degree range, no shade and the likelihood of being surprised by a large venomous brown snake quite high. During blasting operations in the mine, the work area had to be abandoned by persons and machinery 1 hour prior to blasting and up to two hours afterwards. The portability and ease of use made handheld hydraulic products the most effective equipment for this kind of work.
"My original comment to the mine manager on the initial survey is still valid today" says Danny Mitchell, NSW Area Manager Atlas Copco Construction Tools. "Just because something has never been done before, does not make it impossible, improbable maybe, but thinking outside the square, makes anything possible."