HR: 1330h
AN: H42B-1073    [PDF]
TI: An Analysis of Core Log Quality and Hydraulic Test Interval Length on Estimation of Fracture Aperture Statistics
AU: * West, A C
EM: awest@civil.queensu.ca
AF: Queen's University, Ellis Hall Queen's University, Kingston, ON K7L 3N6 Canada
AU: Novakowski, K S
EM: kent@civil.queensu.ca
AF: Queen's University, Ellis Hall Queen's University, Kingston, ON K7L 3N6 Canada
AB: The density of fracturing (i.e. fracture spacings) and the distribution of flow among fractures (i.e. fracture apertures) both play a crucial role in controlling the ability of a bedrock aquifer to attenuate the movement of solute away from a contaminant source. One way to determine these parameters is through hydraulic testing of discrete intervals along boreholes. When the density of fracturing is high compared to the density of test intervals, however, the statistical properties of the fractures are masked by the averaging effect of the testing method. Fracture data collected from the core log can alleviate this problem, but caution must be used in its interpretation. In this study, the relationship between sampling interval length and estimates of the mean and variance of individual fracture spacings and apertures is explored. It is shown that larger test intervals are more useful for estimating the mean of aperture, while smaller test intervals are more useful for estimating its variance. Transmissivities measured at 2 m and 0.5 m spacing across the thickness of a bedrock aquifer in Smithville, Ontario, as well as data from three separate loggings of the core are used to illustrate the relative importance of accurate core logging vs. greater density of hydraulic testing in predicting solute arrival times at a point down-gradient of a contaminant source in a fractured bedrock aquifer.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2003 Fall Meeting