A fleet of 17 Sandvik hydraulic crawler drill rigs is being used by contractor Construcões e Comercio Camargo Correa SA to drill granite on the massive Jirau hydroelectric project now under construction on the Madeira River in north-western Brazil.
The Jirau project, which will have a capacity of 3450MW generated by 50 turbines, is currently one of the largest hydroelectric schemes under construction in the Americas.
Construction is being undertaken by the consortium ESBR Sustainable Energy of Brazil, formed by companies GDF Suez of France (50.1%), Eletrosul (20%), Chesf (20%) and Camargo Correa (9.9%). Camargo Correa, one of Brazil’s largest contractors, is undertaking the civil works.
Jirau will have a rockfill dam 35m high and 550m long, flanked by two compacted earthen dikes, one 930m long and the other 1140m long. The reservoir will cover an area of 258km2. Powerhouses on each bank will house the turbines.
Fleet information
Camargo Correa’s fleet of 17 Sandvik trackdrill rigs include Ranger 600’s and 680RP’s, Dx600’s and seven recently delivered Sandvik Dx700 drill rigs to drill the granite on the riverbank where the dam, spillway and reservoir are being constructed.
The hydraulic, self propelled, crawler-based Dx700 surface drill rig is equipped with a FOPS and ROPS cab and a rod handling system. It is able to drill hole diameters between 64-115mm and has a production capacity of up to 1.2 mt/year.
Across the site, overall drilling conditions vary considerably with a wide variety of rock conditions. Similarly, depending on the application, i.e exploratory drilling, presplitting or drill and blast, determines the number of holes being drilled. Generally, however, the drilling contractor is achieving around 40m per hour.
All seven Dx700 rigs are fitted with 3 inch standard or 2.5 inch Retrac button bits to generally drill 11m deep holes. In order to offer increased longevity of the 76mm drill bits regrinding is carried out on site every 22 drilled metres – due to the hardness of the granite, with the contractor experiencing rock densities of around 2.65t/m³- ensuring extended bit life of up to 1000 drilled metres.
Cofferdams
The course of the river has been temporarily changed with the use of cofferdams to allow the construction work to take place, and also to allow the contractor to prepare the bed of what will be the reservoir.
The Madeira River is the largest tributary of the Amazon, with Jirau located 130km from the nearest town, Porto Velho.
Jirau’s massive site employs an estimated 16,000 workers, most of who are housed in camps at the site itself, and work is being carried out on a 24-hour basis.
Work began on Jirau in 2008 and power generation is expected to begin in 2012. The project is expected to operate at full capacity by October 2016.
