Reaching out for sand and gravel

In the Irish county of Westmeath, contractors Donal Walsh Dredging Ltd have recently added a New Holland E805 excavator – the first such machine in Ireland – to their fleet of equipment already working on a long-term extraction contract at the Derryarkin sand and gravel facility. The site is managed by a joint venture between Bord na Móna (a government organization with responsibility for land usage) and Roadstone Provinces Ltd.

To meet customer requirements, a standard 80-tonne E805 excavator, the largest model in the New Holland range, was configured with a 5.0m3 bucket, an extended dipper arm to give a reach of almost 16m, and other modifications which took the operating weight up to 90 tonnes. The machine was supplied through Roscommon-based McSharry Bros Ltd, Ireland’s only full-line New Holland dealer.

‘Given the highly competitive rates for sand and gravel, we had to consider the best solution for the work’, commented Donal Walsh. ‘The machine had to have a reach of at least 52ft. Fuel consumption and reliability were also extremely important. In addition, we were looking for an excavator that would allow the operator to work at the highest level of productivity.’

The 8m deep gravel bed at Derryarkin lies beneath a layer of peat bog, which for many years had been stripped off to provide fuel for a nearby power-generation plant until the facility closed down. Working in flooded pits approximately 20m wide, the gravel is deposited in stockpiles adjacent to the extraction site prior to loading on to a 1m wide x 650m long field conveyor for delivery to the processing plant.

The crushing, washing and screening facility, which has the capacity to handle 450 tonnes per day, processes the material into various grades from 40 microns up to 50mm. Most of the high-quality product is used for concrete production, roof tiles and drainage stone.

According to joint-venture manager Stephen Murphy, the gravel is currently being extracted from an area of 80ha within a total available area of over 400ha. The current phase has remaining deposits for at least six years and as it is completed the area will be rehabilitated and landscaped to provide a lake and adjacent parklands for community purposes.

The Bord na Móna and Roadstone Provinces joint venture is very aware of the sensitive nature of the work and its responsibility to future generations. By extracting the sand and gravel to create a community feature, they say they are facilitating better usage of the land from which the peat had already been stripped. This work has been acknowledged with the joint venture winning several environmental awards. The finished scheme will encourage wildlife to repopulate the area and is expected to become a tourist attraction.

The company is also conscious of its health and safety responsibilities and has strict procedures for all operatives working on site. This policy has proven so successful that there have been no serious accidents at the quarry since it opened four years ago.

Donal Walsh is very specific about his equipment needs. Established over 10 years ago, his company has contracts at six quarries where the marginal profits demand maximum efficiencies and return on capital investment in equipment.

The contract at Derryarkin includes stripping of the 1m thick layer of peat bog in those areas where it still remains, removal and stockpiling of the overburden and dredging of the gravel beds.

Working a single shift, 5-days a week, the long-reach New Holland E805 is proving to be well suited to these operations. The machine is powered by an Isuzu 6WG1TC turbocharged and aftercooled direct-injection diesel engine, which delivers 340kW at 1,800 rev/min. To increase fuel economy, an auto-idling selector returns the engine to minimum rev/min when all the controls are in neutral.

Further efficiencies stem from the advanced hydraulic system and APS (Automatic Priority System), which, working in conjunction with an engine speed-sensing controller, ensures optimal hydraulic power according to need. The operator can select the preferred work mode from automatic, standard, heavy or light options.

In standard configuration, the E805’s maximum digging depth is 10.5m with a 5.6m dipper stick. Forward reach is 15.65m and dump height is 9.55m.