RED DOG Mine Back Dam Project Cut Off Wall Client : Teck Resources Limited Suite 3300, Bentall 5 550 Burrard Street Vancouver, BC, Canada V6C 0B3 Period of time : 08- 2007 to 09-2010 Type of performance : • Diaphragm c ut off wall to r educe the seepage of a tailings pond for mining production water • Overall cut off wall: 53´000 m² • Cut off wall depth: 15 – 48. m • Wall thickness: 0.80 m • Equipment: BAUER BC 40 on Liebherr HS 885 with at- tached BAUER HTS 50, BAUER BE 500 desanding unit BAUER KBKT 150/400 Booster Pump MAT SK 30 Slurry Mixing Units various MAT Pumps Partner: GOLDER ASSOCIATES INNOVATIVE APPLICATIONS INC. 500, 4260 Still Creek Drive Burnaby, British Columbia V5C 6C6 Project description: The RED DOG Mine located in Alaska, USA is one of the world’s most efficient open-pit zinc and lead mines. Since 1989, the Canadian TECK Resources Limited is operating Red Dog as an open-pit truck-and-loader operation, using conventional drill and blast mining methods. Ore from the mine is shipped to TECK's metallurgical facilities in Trail, British Columbia, Canada and to cus- tomers in Asia and Europe The ore body of the main deposit will remain until 2012, so Red Dog Operations is currently in the permitting process for an extension of their operation by mining the so called Aqqaluk Deposit, which will guarantee a further operation at RED DOG until 2031. One of the licensing requirements was the enlargement of the ex- isting tailing pond for the ore production water coming from the mill. In August 2007, BAUER Resources Canada Ltd., as a subcontractor of GAIA Contractors, started mobilizing a BAUER BC 40 with all required auxiliary equipment. The major challenge of this project was the extremely challenging logistic. Since the Red Dog Mine is a remote site without any adequate road connection, equip- ment transport has to be organized via the mine’s own harbour 95 km west of the mine. The supply of wear and spear parts has to be planned and scheduled in advanced to avoid extra air freight trips to the site. Due to the arctic weather conditions, the work had to be executed between Mai and October. During three arctic summers, a diaphragm wall was executed in hard rock conditions. To avoid any seepage, even in case of melting of permafrost soil layers, the wall had to be cut into competent rock to a depth of 48 m. For embedment of the wall the trench had to be cut in rock with an axial strength (UCS Uniaxial Com- pressive strength) of more than 22,000 psi In September 2010 the 53,000m² cut off wall was successfully completed, characterised by excellent rela- tionships among owner, engineers and contractors. BAUER Resources GmbH, BAUER-Str. 1, 86529 Schrobenhausen, Germany Tel.: +49 8252 97 0, Fax: +49 8252 97 1845 .