Modernizing Deep Groundwater Testing: Rapid Stacked-Dynamic Profiling with Long Screened Test Wells.

Area of Science:

• Hydrogeology
• Environmental Science
• Water Resource Management

Background:

• Conventional zone testing in pilot holes often underestimates constituent distribution in public supply wells.
• Stratified chemical distributions, particularly metals and radionuclides at lithologic boundaries, are frequently missed.
• This leads to wells failing to meet regulatory standards and increased treatment costs.

Purpose of the Study:

• To propose and validate a new approach for characterizing groundwater flow and chemistry in potential public supply wells.
• To minimize the risk of constructing non-compliant wells by providing high-resolution data prior to final installation.
• To integrate advanced sampling techniques with well design for improved water quality predictions.

Main Methods:

• Utilizing the tracer flowmeter and depth-dependent sampler (TFDDS) for detailed flow and chemistry profiling.
• Employing vertically stacked flow and mass balance chemistry profiling of long screened test wells (LSTWs) under pumping conditions.
• Integrating TFDDS data with a spectrum of drilling methods for rapid hydraulic and chemistry data acquisition.

Main Results:

• The proposed approach generates a detailed distribution of anthropogenic and geogenic constituents within saturated zones.
• Characterization includes both permeable sediments and contaminant-laden boundaries between sediment types.
• High-resolution data enables informed predictions of new well compliance with regulatory standards.

Conclusions:

• The integrated TFDDS and LSTW profiling approach enhances the accuracy of groundwater resource characterization.
• This method is crucial for designing public supply wells that yield compliant drinking water.
• Case studies demonstrate the utility for both new well design and managed aquifer recharge projects.