Automatic Delineation of Capture Zones for Pump and Treat Systems: A Case Study in Piedmont, Italy

Abstract

The design of a pump and treat (P&T) system for the hydraulic control of a contaminated plume in a confined aquifer is presented here. Being the system designed for the emergency containment of a nonaqueous phase liquid plume, the evaluation of the system’s short‐term efficiency was considered an important issue. For this reason, both time‐related and ultimate capture zones were defined. They were traced using the automatic protection area (APA) model, a capture‐zone delineation tool based on a hybrid forward‐backward particle tracking algorithm, that provides an automatic post‐processing encirclement of capture zones. Two simple indexes are here proposed for the evaluation of the performance of the hydraulic barrier, that is, the efficacy and efficiency indexes, calculated from the capture areas provided by APA. The discharge rates of the wells were dimensioned applying the APA algorithm, maximizing efficacy and efficiency of the barrier. Results proved both visually (via plotting of capture zones) and numerically (via calculation of the indexes) that the P&T system can provide a complete capture of the contaminated area and minimizes the volume of extracted water. Consequently, the APA algorithm was proved to be a useful tool in capture zone delineation. As a future perspective, it could be coupled with the real‐time measurement of pumping rates and water levels and be implemented as a part of a tuning tool for the management of the hydraulic barrier.

A Revised Conceptual Model to Reproduce the Distribution of Chlorinated Solvents in the Rho Aquifer (Italy)

“…In the metropolitan area of Milan (Northern Italy), chlorinated solvents are responsible for more than 50% of the total solute plumes observed (Provincia di Milano 2002). When aquifer pollution is detected, pump-and-treat (P&T) and slurry walls or barrier systems (BS) are commonly combined to promptly prevent the risk of the pollutant spreading to critical receptors in clean zones, such as drinking water supply wells (Tosco et al 2010).…”

The Value of Groundwater Modeling to Support a Pump and Treat Design

“…For the development of an effective P&T design, groundwater flow models can support decisions concerning well location and minimum groundwater extraction rates necessary to achieve the required capture zone, whether or not combined with an optimization model (USEPA ; Boice ; Chang et al ; Tosco et al ). Unlike trial‐and‐error simulation, optimization models succeed in identifying the optimal design solution within the required time horizon at a minimum cost (Chang et al ; Culver and Shoemaker ; Huang and Mayer ; Ahlfeld et al ).…”