New Paper Available: Cross-hole fracture connectivity assessed using hydraulic responses during liner installations in crystalline bedrock boreholes.

We are pleased to announce the publication of a new article in the Journal of Hydrology from the G360 Institute Team.

Cross-hole fracture connectivity assessed using hydraulic responses during liner installations in crystalline bedrock boreholes:
Persaud*, E., Levison, J., Pehme*, P., Novakowski, K., Parker, B.L
DOI: 10.1016/j.jhydrol.2017.11.008

The authors would like to acknowledge time and effort of G360 staff, especially Ryan Kroeker and James Hommersen, for the field activities involved in this study. Thank you also to Peter Kitanidis, Paul Hsieh and three anonymous reviewers whose constructive comments helped to improve the quality of this manuscript.

This work was supported by a Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant [grant number 03973]; the NSERC Canada Graduate Scholarship Program (Master’s); and the Ontario Graduate Scholarship Program.

In order to continually improve the current understanding of flow and transport in crystalline bedrock environments, developing and improving fracture system characterization techniques is an important area of study. The presented research examines the installation of flexible, impermeable FLUTe™ liners as a means for assessing cross-hole fracture connectivity. FLUTe™ liners are used to generate a new style of hydraulic pulse, with pressure response monitored in a nearby network of open boreholes drilled in gneissic rock of the Canadian Shield in eastern Ontario, Canada. Borehole liners were installed in six existing 10–15 cm diameter boreholes located 10–35 m apart and drilled to depths ranging between 25–45 m. Liner installation tests were completed consecutively with the number of observation wells available for each test ranging between one and six. The collected pressure response data have been analyzed to identify significant groundwater flow paths between source and observation boreholes as well as to estimate inter-well transmissivity and storativity using a conventional type-curve analysis. While the applied solution relies on a number of general assumptions, it has been found that reasonable comparison can be made to previously completed pulse interference and pumping tests. Results of this research indicate areas where method refinement is necessary, but, nonetheless, highlight the potential for use in crystalline bedrock environments. This method may provide value to future site characterization efforts given that it is complementary to, and can be used in conjunction with, other currently employed borehole liner applications, such as the removal of cross-connection at contaminated sites and the assessment of discrete fracture distributions when boreholes are sealed, recreating natural hydraulic gradient conditions.

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