Hayley Pothier

The town of Bridgetown, Nova Scotia is considering switching its municipal fresh water supply from surface water to groundwater to help lower operational and maintenance costs. Preliminary chemical analysis of the groundwater has shown elevated uranium concentrations. The purpose of this study is to determine if the source of uranium in the groundwater is within the Triassic Wolfville Formation aquifer, which underlies the Bridgetown region. Drill core from Paradise, near Bridgetown, and well cuttings from the test wells at Bridgetown, were analyzed and logged to better understand the stratigraphy of the Wolfville Formation and to determine which, if any, horizons have elevated uranium that can be leached into the groundwater. Spectrometer assays were conducted on Paradise drill core and results indicated that horizons within the core have up to twice the background levels of uranium. Samples from these horizons along with well cutting samples from the Bridgetown wellfield underwent both acid and aqueous leachate testing. Test results indicate that leachable uranium is present in the rock, although concentrations in the leachate are still below values previously measured in well waters. These results suggest that the Wolfville Formation may indeed be a source of leachable uranium in the groundwater. Further leachate testing on bulk rock samples should be done, as results from the study on >74m sediment suggests that there is mobile uranium available even in these coarse grained fractions. The results of this study would also suggest that continued monitoring of uranium concentrations in production wells in Bridgetown be continued.

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Pages: 71
Supervisor: Anne-Marie Ryan