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Impala Team on Track at #20 Shaft

Attitude may seem like a small thing, but it is attitude that has had a definite impact on the Impala No 20 Shaft contract.

"The approach by all involved in this project has been different and it shows. Our primary objective was always to make it work, and this was made simpler because the plan with which we started was realistic and achievable. This plan has enabled us to achieve significant milestones from the beginning, and each of these successive achievements has bred further success," says Freddie Geldenhuys, business manager, Murray & Roberts Cementation.

"Another factor is the fact that the team which started on the project has remained intact for the last 18 months. We have created a tidy site, which has had a positive impact on the productivity and mindset of workers by creating a pleasant working environment. Small things have made the difference - there have never been any squabbles, claims or any untoward behaviour and open communication between all parties. We have usually been able to find win/win solutions and this has proved successful," Gerrit Strydom, contract manager for Murray & Roberts Cementation, says.

The Impala No 20 Shaft Project is located north of the No 12 Shaft on the north west corner of Impala’s mining lease area. The scope of Murray & Roberts Cementation’s contract covers the sinking and equipping of a main downcast shaft, an upcast ventilation shaft, service infrastructure on the surface and all ancillary excavations and access development necessary to establish the footprint for a mine capable of producing 185 000 reef tonnes per month. Initially Merensky Reef will be mined and later it will be UG2.

The shafts at Impala No 20 shaft are strategically positioned in the centre of blocks A and B to mine the Merensky and UG 2 ore bodies. Rock removal and men and material transportation will be via a decline system situated below the Merensky reef plane. A conventional rail bound rock transport system positioned in the footwall below the reef on each mining level will provide reliable and cost effective production performance.

This system provides some flexibility to negotiate the frequent reef displacements caused by faulting. A foot wall decline situated close to the central axis of the reserves is equipped with a high capacity conveyor and will transfer rock from the haulage ore passes to the rock loading facilities at the hoisting shaft. Surface silos will store the rock for loading to the surface rail system for delivery to the concentrator.

"The sinking is currently approximately 80% complete, with the main shaft at 707 metres and the ventilation shaft at 865 metres. At the beginning of May 2006 we had completed one station on the main shaft, and were 100 metres away from the next," Strydom comments.

The main shaft will have five stations in total, while the ventilation shaft will have four. The ventilation shaft intersected the Merensky reef at 862 metres below surface and this is where Murray & Roberts Cementation is currently busy with the first station development; the other three will follow.

The method selected is a vertical shaft with a decline shaft system attached to it, as this minimises lateral development and will shorten the time to get to reef. This vertical shaft with decline system comprises a winder and cage to a single station on 90 level, which is about 900 metres below surface. There are two declines from 90 level – one a material decline which will be equipped with a material monorail and the other is an access decline equipped with a chair lift. On 94 level - 940 metres underground, there will be two more declines – one equipped with a belt which will bring ore to the main shaft and the other a service decline.

The main shaft will have a completed diameter of 8.5 metres to a depth of 1051 metres and the ventilation shaft will have a diameter of 6.5 metres and a depth of 977 metres. The main shaft will provide capacity to hoist up to 185 000 tonnes of ore and waste per month. Refrigerated air will enter the main shaft and be exhausted from the ventilation shaft.

The sidewalls are supported by means of cladding and splitsets with an overlapping system. From the sinking stage, the shaft concrete lining is placed concurrently with the sinking operations – with the exception of the breaking and lowering of the curb ring – during which time there are no activities at the bottom. The main sink is being carried out using multi-boom drill rigs and cleaning is done by means of cactus grabs loading into 10 ton and 12 ton kibbles.

The shaft bottom in the ventilation shaft will be reached during 2007 and the main shaft bottom in early 2008. On completion of sinking, equipping of the main shaft will commence and shaft bottom loading arrangements will be installed in the ventilation shaft. After this, Phase 1 access development will begin from the ventilation shaft with concurrent equipping of the main shaft. Handover of the project is planned for early 2009.

"The block of ground being mined goes from 600 metres down to 1000 metres in depth and is some 2.5 km x 3.5 km in extent. It is anticipated that the mine will reach full production in 2011 and is expected to have a 20-year life span. This is Impala Rustenburg’s last relatively shallow block of mining lease available," Alistair Hodgkinson, project manager for Impala, says.

The project was initially approved in October 2004, with site establishment taking place during October 2004. The main sink of the vent shaft began in June 2005 and the main shaft in August 2005.

"In the 12 months since site establishment, we have commissioned two full sinking shafts and completed 1000 metres between the two shafts. This is regarded as a significant milestone – we consider this to be a good figure to aim for on a new project i.e. 1000 metres on two shafts in a year, including commissioning," Strydom says.

This has been achieved with sinking on both shafts running at an average rate of 3.6 metres per day. This impressive achievement is on the back of a good safety record. On 5 April 2006, the team reached 500 000 man LTIF (Lost Time Incident Free) hours, which is a further milestone on the contract.

Another landmark worth mentioning is that from the start of the main sink in June 2005 to the beginning of May 2006 more than 100 metres per shaft per month have been achieved on five separate occasions.

Reflecting on these many notable achievements, the question is how the team has performed so well on a single project. "From the start, the plan was to achieve these high statistics and this is attributable to a number of factors including the excellent level of team work and communication," Geldenhuys comments.

This conventional shaft sinking project is operating with two teams, one that was previously responsible for the South Deep shaft and the team from Black Mountain. (South Deep was the deepest single hoist shaft in the world. The Black Mountain ventilation shaft was completed fatality free.) The crews within the teams depend on each other; the two teams have not worked together on the same projects

A team is dedicated to the vent shaft and the other main shaft. Everyone on the project knows what the primary objective is - to finish this project by the end of 2008 incident free, meeting internationally accepted quality and safety standards and ahead of schedule and on budget. "We are confident that this is will achieved," Strydom says.

To achieve this, the overall project objective is broken down for all individuals with daily, weekly and monthly targets to be achieved. These are unambiguous targets and are clearly understood by all. The project targets were put in place by Murray & Roberts Cementation and are closely controlled and monitored.

Another important factor is that on this project there is a single plan and everyone works to it, including the client which is Impala Platinum, the EPCM is TWP Consulting Ltd and the contractor Murray & Roberts Cementation. All three have a good working relationship.

With respect to the challenges on the project - during the first ten months while preparing for the main sink, there were multiple companies working in the same place simultaneously including civils, structural steel and electrical contractors among others.

"This had major implications for safety and quality. At one stage, during the peak of site establishment, there were two tower cranes and 17 mobile cranes, apart from other equipment and 800 people. This called for tight control of the site to ensure that the project remained on schedule and that safety and quality standards were met. We currently have an average of 550 people on site," Strydom says.

The project is surrounded by four communities which are jointly called Macharora and they have been involved from the initial assessment phase. "We have a good relationship, and from the start of the project have maintained good communication. Members of the local community are currently employed on the project and are being introduced into this business, with skills being gained and smaller contracts are being awarded to emerging contractors from this community. Impala is active within the local community and identifies people within the local community that are employable within the Impala structure and facilitates their employment on an ongoing basis," Tom Sertic, deputy project manager for Impala, says.

Training is ongoing at the Murray & Roberts Cementation training centre on site and at Bentley Park, where refresher training and skills training for machine operators are done. An on-site training officer implements site-specific training including HIV awareness.

"A further difference is that all skilled employees are housed in a town house complex in Rustenburg, providing greater stability for families. This underscores our belief that our employees are our most important asset," Geldenhuys says.

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