Characterizating a fractured rock aquifer with hydraulic testing at a contaminated municipal well using flexible liner methods and depth discrete monitoring
Two shut down contaminated municipal wells became the focus of an investigation to understand the local hydrogeologic regime so that options for re-use of these well could be assessed. This study involved the application of new methods including the use of FLUTe flexible liners as well as a pumping test to characterize the aquifer. Hydraulic apertures were calculated from transmissivity measurements to study the range and distribution of values and estimate bulk effective fracture porosity calculated to be 5x10-4. The low effective porosity suggests very rapid groundwater velocities through the aquifer and has important implications for contaminant transport times and aquifer vulnerability to contamination. Monitoring in nearby multilevel wells indicated that the Smallfield well has been acting as a conduit for vertical cross-connection and potential contaminant migration across mechanically isolated hydrogeologic units. Lengthy persistence of low level contamination is expected should the Smallfield well become operational in the future.