Surfactant/cosolvent flushing is a DNAPL removal technology involving the injection and subsequent extraction of chemicals to solubilize and/or mobilize DNAPLs. The chemicals are injected into a system of wells positioned to sweep the DNAPL source zone within the aquifer. The chemical flood and the solubilized or mobilized DNAPL is removed through extraction wells and the liquids are either disposed or treated onsite. The technology is a mature technology in the petroleum-engineering field of Enhanced Oil Recovery (EOR), supported by decades of research and field tests. Environmental applications constitute a new usage for the technology, and have become more common in recent years. The technology has been shown to be effective for several DNAPL types, including spent degreasing solvents (TCE and TCA), dry cleaning solvents (PCE), heavy fuel oils and coal tar/creosote. Laboratory work has also demonstrated applicability to PCB-containing mineral oils. The primary appeal of the technology is its potential to quickly remove a large fraction of the total DNAPL mass. Technical challenges include locating and delineating the DNAPL source zone, estimating the initial DNAPL mass and spatial distribution, characterizing the hydraulic properties of the aquifer, delivering and distributing the injected chemicals to the targeted zone, and designing the optimum chemical formulation for a given DNAPL composition and soil type. Typical concerns include the cost of disposal of the effluent, regulatory permitting for underground injection of tracers or flushing agents, the overall impact of unremoved DNAPL, and the expertise of the personnel involved in site remediation.
The purpose of this training is to familiarize you with the recently released ITRC Technical and Regulatory Guidance for Surfactant/Cosolvent Flushing of DNAPL Source Zones (DNAPL-3). This document provides technical and regulatory information to help you understand, evaluate and make informed decisions regarding potential surfactant/cosolvent flushing projects. Included is a description of the technology, system operation, performance assessment, regulatory considerations, stakeholder concerns, case studies, and technical references.