MEASUREMENT OF GROUNDWATER FLOW RATE AND DIRECTION IN THE ALLUVIAL FOUNDATION OF MICA DAM, BC, CANADA

摘要

The downstream shell of Mica Dam was constructed on alluvial deposits in the order of 40 m (130 ft) thick at mid-valley, and these primarily granular materials act as the downstream drain of the dam. Groundwater passing through the drain discharges directly into tailwater, and collecting this flow by conventional means such as weirs is not practical. Relative drainage rates are currently inferred from measurements of hydraulic gradient in the drain. BC Hydro has undertaken a pilot study to assess the viability of using a Heat Pulse Flow Meter (HPFM) deployed within a standpipe piezometer to monitor flow rate and direction in the drain. This paper provides background information on the geology and groundwater flow regime at the toe of Mica Dam, describes the planning and initiation of the pilot study, and presents preliminary data collected during the first 6 months of the study.