Challenges in Conducting a Hydrogeological Study and Results on a Potential Iron Deposit Located in a Remote Site within the Labrador Trough


Vincent Mlakar, Blumetric Environment inc; Rich Schmidt, Blumetric Environmental Inc.

BluMetric Environmental conducted a hydrogeological and geotechnical study to support the Bankable Feasibility Study and Environmental Impact Statement in northeastern Labrador.  The deposit is only accessible by air (helicopter) either directly from Schefferville, or via road from Schefferville to the camp site on the shore of Attikamagen Lake and then by helicopter. Considering the site is surrounded by water, that groundwater is encountered at about 30 m bgs and the pit will be about 150 m deep, it is likely that dewatering will be an issue for this Project.  Furthermore, the ore, its geology and possible structural faults crossing the region would be another indication of possible interaction between groundwater and surface water. A preliminary hydrogeological program was designed and executed to characterize the site, to predict potential impacts from pit dewatering on surface water bodies, to develop mitigation plans to address those impacts, and to develop and pit dewatering plan. The scope of the field program involved a drilling program and a testing campaign using diamond drilling to a maximum depth of 173 m, and targeting whole hydrostratigraphic units. A comprehensive packer test program was conducted to obtain information on hydraulic conductivity for various depth intervals. Subsequently, a pumping test program was carried out to determine bulk hydraulic properties and groundwater quality. The data collected in this field campaign was then applied to construct a groundwater model of the site to determine groundwater flow conditions and to determine preliminary pit dewatering requirements.  Simulations of the model allowed a preliminary assessment of potential impacts to surface water features as a result of pit dewatering The current presentation weighs in on planning a successful field campaign, focusing on the logistics of the field program and appropriate data collection methods under various constraints brought about by site accessibility, schedule and adverse seasonal weather.  The results of the investigations and the subsequent groundwater flow modeling will also be presented.
Mots Clés: hydrogeology,dewatering, impacts on surface water features, remote site,