Assessment of Vertical Hydraulic Connectivity in a Multilayered Aquifer-Aquitard System in Response to Deep Bedrock Pumping Using High-Resolution Spatiotemporal Monitoring

Abstract

This study investigates a multilayered fractured bedrock aquifer-aquitard system overlain by complex moraine and ice-marginal deposits in Guelph, Ontario where a new bedrock municipal supply well is proposed adjacent to a provincially significant wetland as a complement to an established municipal well field. The main objectives of this study are to assess the vertical hydraulic connectivity and potential hydrologic impacts across the multi-layered bedrock and overlying Quaternary sediments through an improved conceptualization of hydrostratigraphic units within the complex lithostratigraphic sequence in response to a 30-day pumping test. Multiple high-resolution datasets collected in one bedrock borehole and four Quaternary boreholes were used to inform the design and installation of custom-built multi-port systems instrumented with pressure transducers for continuous monitoring of hydraulic head. Regression deconvolution was used to separate multiple anthropogenic and natural signals from the water level data and generate constant rate pumping response functions, which were used to determine and interpret the hydraulic responses to pumping. This research will support decisions regarding the municipal well capture zone and sustainable pumping rate to minimize impacts to shallow groundwater and the natural environment.