Technical Report NTB 90-44

Stripa ProjectPrediction of inflow into the D-holes at the Stripa mine

Groundwater flow through three-dimensional networks of discrete fractures was modelled to predict the flux into a set of parallel boreholes, as part of the Site Characterization and Validation Project conducted during Phase 3 of the Stripa Project. Influx was predicted from fracture statistics derived from geological, geophysical, and hydrological site characterization data. Individual fractures were treated as probabilistic (random) features, whereas the major fracture zones inferred from geophysics were treated as deterministically located zones of relatively high fracture intensity. The flow predictions were produced by generating multiple Monte Carlo realizations of the fracture population, and by solving the flow equation for each population using the finite element method. The predictions thus produced are presented in the form of probability distributions for flux. The most likely value for total influx to the boreholes was predicted to be 90 litres/hour, with a 90 % confidence interval extending from 30 to 5700 litres/hour.