Schlumberger Water Services worked as part of the Kennecott pre-feasibility team to conduct a detailed surface water and groundwater characterization program for the proposed Collom open pit coal mine.  The scope included surface water characterization, installation of flumes, spring and seep surveys, installation of piezometers and monitoring wells, water sampling, single and multiple hole pumping tests and development of regional and site-specific groundwater models.  Piezometer installations included single-hole standpipes and multiple level, spring loading vibrating wire piezometers that could be grouted into the hole without using filter pack material.

The proposed mine is planned to be over 650 feet deep so that requirements for mine dewatering and slope depressurization were carefully evaluated during the pre-feasibility study.  A site-specific finite element model was used to predict hydraulic head conditions for various slope configurations and depressurization measures.  The model results were integrated into the geotechnical slope stability model done by others.  A regional groundwater model was developed that included the proposed mine area, an existing mine and periphery areas.  The model incorporated the complex layering of the coal deposits, a regional water balance and observed head conditions.  It was calibrated to steady-state and transient pumping conditions and forms the basis for evaluation of potential hydrologic consequences of mining.  The results of the work provide a basis for both the pre-feasibility report and for environmental permitting documents.