Sandvik Drill Rigs Tackle Brazilian Hydropower TunnelsThe Simplicio power plant will be the second largest hydroelectric power plant in the state of Rio de Janeiro, with a 334 MW generation capacity. This will supply enough energy to a city with a population of of 1.5 million. In 2010, when it starts to operate, Simplicio will represent a 28% increase in the offered hydropower capacity in Rio de Janeiro, which currently relies on 10 hydroelectric power plants, with a 1,220 MW generation capacity. Simplicio is located by the Paraiba do Sul River, bordering the municipalities of Sapucaia and Três Rios (state of Rio de Janeiro) and Chiador (state of Minas Gerais). The investments in the power plant will create 4,000 direct and 10,000 indirect jobs, and also contemplates the construction of waste treatment stations and lakeside environmental preservation areas. Taking advantage of the topography of Brazil’s Vale do Paraiba do Sul with its high-sided slopes and strategically positioned cofferdams, the project features a powerhouse for three 102 MW turbines, eight water channels (C1 to C8), four tunnels (T1 to T4 and access tunnels, stretching for 12 km in total) and five reservoirs (Tocaia, Louriçal, Calçado, Peixe and intake channel) over a distance of 26 km to virtually introduce a new water course. The overall project also includes construction of a dam and a 2 x 14 MW power plant in the Paraiba do Sul close to the town of Anta. This construction includes a 30 m-high x 270 m-wide RCC dam, spillway and intake. The new reservoir will cover an area of 12 sq km and also feed water into the first channel at the start of the rerouted waterway.The contract for the operation and maintenance of both the Simplicio and associated Anta hydroelectric power stations has been awarded to Furnas Centrais Eléctricas. Furnas is responsible for generating almost 10,000 MW installed capacity from 11 hydroelectric and two thermoelectric power plants, which is approx. 11% of Brazil’s total energy generation.The Brazilian Development Bank (BNDES) and Furnas Centrais Elétricas signed on 27th March a BRL1 billion contract for the construction of the plant. The total investment is BRL1.6 billion, 62% being BNDES's participation. TunnellingThe Simplicio hydropower plant began its works at the end of 2006. Throughout the tunnelling operations, the JV is relying on five Sandvik jumbo drilling rigs including a DT11 (formerly named Axera T11), purpose-ordered by Andrade Gutierrez, and two DT8 (formerly Axera T8) by Norberto Odebrecht. The fleet also includes a second DT11 and a DT8 on-rental to the JV, all featuring three booms and TCAD (with the exception of the rental DT11). Visit www.miningandconstruction.sandvik.comThe Sandvik tunnelling jumbo DT11 has been designed for fast and accurate tunnelling excavation of 20-177 sq m and capable of operating in a 10.9 x 18.2 m tunnel. The Sandvik DT series is built from modular components and offers different size coverage areas and instrumentation / automation levels with operational features ensuring the most suitable unit for each job. The series offers uncompromised reliability and low operating costs with high penetration rates. An integrated drill carriage and optional stabilizer ensures smooth drilling even with long rods.TCAD (Tamrock Computer Aided Drilling) face drilling instrumentation ensures improved excavation quality with significant time and cost savings with accurate drilling to reduce overbreak and the corresponding amount of concrete use for lining. Drill patterns can also be optimized for maximum advance percentage. All five jumbos also feature Sandvik rock tools to offer further enhanced production including 4.3 m-long Sandvik R38, Hex32 and R32 rods, 51 mm-diameter R32 drill bits and R38 shanks. Face drillingThe rock type in all the tunnels is gneiss with a typical hardness of 200 MPa. Typically, a total of 135 holes are drilled for each blast, drilling 3 m-long holes to ensure an advance of 2.85 metres (95%) and a blasted 264 cu m volume of rock.Within the drilling pattern, 16 blast holes are drilled including three cut holes reamed to 102 mm. The drilling pattern typically features 14 foot holes across the 18 m width and 39 contour holes, with the remaining 66 holes spaced at radii of 5.05 m, 6.25 m and 8 m. Using Sandvik R32 button bits to produce 51 mm-diameter holes, the contractors are completing all 135 holes within 2 ½ hours. The sequence continues with 1-1 ½ hours charging, 40 minutes blasting and ventilation and up to two hours scaling and mucking out. Crews generally aim for three blasts a day on both faces inside the long tunnel, two on one face and one on the second face.The average life of the Sandvik tools in the gneiss rock was almost 5,000 drilled metres for the shank adapter and 2,500 metres for the H32 rod. Crews are also achieving 300 metres with the drill bits averaging seven holes before regrind. It is possible to regularly achieve six to seven regrinds with each bit, a good production rate. View pictures here.Route description and work progressWork was scheduled to start on channel C1 in April 2008 along a distance of 1.9 kilometres. Featuring a final width of 28 metres, the channel will have a water depth of 8 m and flow into the first tunnel T1. At 1,458 km long, the tunnelling was started earlier this year using the first Sandvik DT8 jumbo rigs drilling from the direction of channel C2.To date almost 50% of the preparation of C2 has been completed with more than 100,000 cubic metres of rock being excavated along the 1 km channel to lead into the Tocaia reservoir, the first of a series of five. Making use of the topography and a dyke, the valley forms a natural water storage area, before feeding into the 565 m channel C3 and second tunnel T2. Depending on the blasting sequence, the Sandvik DT8 jumbo is used for drilling tunnels T1 and T2.Work was also scheduled to begin in April for the start of the short 85 m-long channel C4 leading to tunnel T2A and a 105 m-long continuation of channel C4.The network continues with the Louriçal reservoir, the second of the project, which includes two dykes to hold back water before feeding into a natural channel and onto channel C5.The third reservoir in Calçado includes the largest dyke at 75 m high and 400 m wide. With a series of tributaries feeding all the reservoirs, Calçado includes a small penstock to release water maintaining a minimum amount into its natural river course.A short 73 m-long channel feeds into tunnel T3, the longest of the project. At 6.03 km, T3 is divided into six working faces with access relying on two 300 m-long access tunnels spaced approximately 2 km apart. Both access tunnels have been driven using a second Axera T8 jumbo rig on the 7 m-high x 8 m-wide access. Throughout tunnelling in T3, the JV is relying on four of the five Sandvik jumbos with each working on up to two faces.Tunnelling is currently underway on all six faces to excavate the top bench, with a 7.5 m height x 15 m width, the same size for all the tunnels. Once completed, work will begin on the lower bench to a height of 7.2 metres to provide a final tunnel height of 15.7 metres.By March excavation had progressed from the upstream portal to 700 metres and 400 metres from the downstream portal. In between advances of 300 metres, 200 metres, 100 metres and 80 metres had been made with advances of up to 6 m/day on each face.T3 feeds the 202 m-long channel C7 serving a fourth reservoir (Peixe) featuring three dykes to retain the water. The flow continues into the intake channel, dropping into three 300 m-long feed tunnels (one for each turbine) over an 80 m drop at a gradient of 12.48%.After the Simplicio powerhouse, a 760 m-long tailrace open channel feeds the water back into the Paraiba do Sul river, more than 26 km down the river. 22/08.