PNNL

Pump-and-treat (P&T) systems are one of the most commonly used methods for hydraulic containment and treatment of contaminated groundwater. These systems extract contaminated groundwater through pumping wells and utilize an above-ground treatment system to remove contaminants. Treated water can then be sent offsite and/or reinjected into the subsurface.

While P&T operations can be effective for groundwater remediation, maintaining their performance has been identified as a challenge at many sites. As the remedy progresses from initial design and implementation through continued operation over time, contaminant removal typically diminishes due to site complexities, such as heterogeneous geology, large capture zones requiring multiple pore volume flushes, the presence of source zones, diffusion-limited mass transfer, co-located and/or recalcitrant contaminants, and dispersed contaminant distributions. Furthermore, at many contaminated sites using P&T, short-term response actions were needed at the startup to focus on mitigating immediate risks to receptors. As a result, the initial design of P&T systems often focused on large-scale containment and bulk treatment rather than the most optimized system to provide maximized and/or sustained contaminant removal to achieve a certain end state, contributing to plume persistence and limited effectiveness of the P&T systems.

Performance-based optimization and/or management of P&T remedies is a critical strategy for maintaining contaminant removal effectiveness throughout the remedy’s lifetime and managing systems toward a certain end-state for site completion or a remedy transition.

In this Center for the Remediation of Complex Sites (RemPlex) seminar on February 20, Inci Demirkanli and Xuehang Song from Pacific Northwest National Laboratory will present a pre-screening tool developed to conduct end-state-driven P&T performance evaluations. They will discuss how the tool provides a systematic and adaptive approach that couples a simplified field-scale model with optimization algorithms to assess the potential impacts of various P&T management strategies and specific site features on multiple remedy objectives. The tool does not replace more comprehensive high-resolution P&T models but provides a pre-screening level comparison of P&T system behavior to achieve a certain end state.

The seminar is from 11:30 a.m. to 1:00 p.m. Pacific time. Registration is free and open to the public. Register in advance on Zoom and subscribe to the RemPlex newsletter to receive future announcements.