Authors: R. Woolgar, A. Pryse-Phillips, J. Hiscock
Canadian Dam Association Conference, Winnipeg, September 2008
Abstract
Digital modeling of geological and hydrogeological data for the foundation design and analysis of the proposed Conawapa Generating Station in Northern Manitoba has been part of Manitoba Hydro’s Recommitment Study (Stage IV) following the project’s suspension in the early 1990s. 3D geological and hydrogeological models have been developed to consolidate and improve the designer’s ability to understand all of the information; and to assist in developing engineering alternatives which will
improve the overall confidence of the design. The tools are also being leveraged for use in environmental studies. Conawapa’s unique site location, geology, and groundwater conditions also present significant challenges related to amassing data collected during many years of investigations. The geological and groundwater models for Conawapa were constructed utilizing modularbased Mining Visualization System (MVS) and finite element FEFLOW programs, respectively. In house custom-built utilities were developed to extract model input information from existing geological data management systems (gINT). Other tools were also developed to enhance the exchange of datasets and visualization between MVS and FEFLOW. The site geological model combines topographic, bathymetric, geotechnical, and geophysical data, including bedrock fracture permeability, into a comprehensive visualization and analysis tool. The groundwater models were calibrated using detailed groundwater monitoring, pumping test and permeability test data, and were used as predictive tools to evaluate and visually describe the groundwater conditions. The tools will assist in the design and analysis of various critical conditions, such as grouting design assessment, seepage quantities during construction, and during impoundment and operation. While automated processes were employed to filter, segregate, and organize existing databases, the importance of a well planned conceptual model, and the subsequent manual
checking of all input data, is critical in constructing representative and robust hydrogeological models. These models will serve the full life cycle of the plant from design, construction and through performance monitoring.
