080121-08MN006-Sabina Hackett River Project Proposal ... - NIRB

Project Descriptionmultiple-culvert installations or large culverts). These culverts will be sized for runoff duringspring snow-melt, which will be high. There will be a bridge required over the Hackett Rivercrossing, and possibly other crossings as we the prefeasibility study assessment continues.One additional requirement for the spur road is that it should run close to a potential water sourcefor the mine. Sabina will be allowed to pump only a limited amount from each water source(which must therefore be large in area).Option 2, south road, is considered to be the most feasible alignment, which meets therequirements listed above and, in addition, crosses the Hackett River at a better location than doesoption 1, north road (which crosses the river at a point with high banks). In addition, suitablewater sources exist close to option 2 at D’Arcy Lake south of this alignment and another lakesoutheast of the spur road/BIPR connection.About 7 km west of the BIPR and south of a long narrow lake, option 1 crosses an area of veryrugged topography (bedrock). This harsh terrain will make it difficult to construct a road alongthis alignment and this would not be the preferred option from a constructability point of view.In addition, several archaeological sites exist along the Hackett River near the option 1 crossing.These sites would be difficult or impossible to avoid. Hence, option 2 is the preferred optionfrom an archaeological point of view.2.8.2.2 Evaluation of Geotechnical Conditions Along the AlignmentsPreliminary tasks before road alignment begins will include the identification of unsuitable areasof subgrade. Geotechnical conditions along the alignments will be evaluated from existing mapsand a site visit. The geotechnical engineer will pay particular attention to:• permafrost areas• eskers• swamps• unstable areas• potential borrow pits and quarry sites2.8.2.3 Establishment of Preliminary Road AlignmentOnce sufficient information has been accumulated to identify the potential engineering,hydrological, geological, archaeological and environmental problems, a roadway alignment willbe established that will minimize environmental impacts and maximize performance. The exactroute will be determined in conjunction with the appropriate government environmental agency.After evaluation of the preliminary road options, designers will develop a preliminary roadalignment for further analysis. They will, while avoiding unfavourable construction areas, suchas eskers, wildlife dens and habitat, areas with steep grades, and unstable areas:• design a vertical alignment without steep grades that will slow haul trucksJanuary 2008 Hackett River Project – Project Proposal Sabina Silver CorporationReport Version B.1 2–37 Rescan Environmental Services Ltd. (Proj. #833-2)