HR: 0800h
AN: H21C-1361    [Abstracts]
TI: The Results of a Radial Divergent Tracer Experiment Conducted Over the Full Thickness of a Horizontally Fractured Dolomite
AU: * Melaney, M A
EM: melaney@civil.queensu.ca
AF: Queen's University, Department of Civil Engineering, Kingston, ON K7L3N6 Canada
AU: Novakowski, K
EM: kent@civil.queensu.ca
AF: Queen's University, Department of Civil Engineering, Kingston, ON K7L3N6 Canada
AB: In several recent field studies it was concluded that highly transmissive features are key to the movement of mass in horizontally-fractured bedrock aquifers. In many cases these features can be hydraulically identified in individual boreholes and correlated from borehole to borehole. The purpose of this investigation is to determine the relative role of these hydraulic features in transporting in the horizontal direction where the source of mass is distributed uniformly with depth. To explore this, a radial-divergent tracer experiment was conducted in a four-borehole array completed through a horizontally-fractured dolomite in Smithville, Ontario, Canada. The injection interval created by the dual packer injection system spanned over 8.6m vertically. This injection interval included several identified features located in the Upper Eramosa of the Lockport formation. Utilizing a fire hydrant as a water source, a flow field was established by injecting water at a rate of 21.4 L/min. After the flow field had been established, 500 L of Lissamine FF (a conservative fluorescent dye tracer at a concentration of 200mg/L) was injected at a rate of 23.25 L/min. To allow for a consistent flow field throughout the experiment, water was injected behind the tracer at 20.4 L/min. The sampling wells were fitted with a packer in order to isolate the entire Eramosa section. A submersible fluorometer outfitted with a pressure transducer was used to detect the arrival of tracer in the sampling wells. The pressure transducer was used to identify the exact depth where fluorescence signals were detected. Correlating the fluorescence signals at depth with hydraulically-identified features provided an in-situ measure that identified the role of each feature with respect to mass transport. Over 100 vertical fluorescent profiles were collected among the four wells, and the peak concentration profiles in each well exceeded 85 ppb. Preliminary analyses indicate that specific highly transmissive features carry more mass than other features of similar transmissivity. The data also indicates that each well exhibits a unique mass transport behaviour and unique fluorescent signature. The results of this experiment suggest that mass transport and the associated interactions are more complex than previously surmised.
DE: 1828 Groundwater hydraulics
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
DE: 1895 Instruments and techniques: monitoring
SC: Hydrology [H]
MN: Fall Meeting 2005