Sites contaminated by chlorinated solvents present a remediation challenge. Chlorinated solvents are among the most difficult groundwater contaminants to remediate, especially at sites with dense, non-aqueous-phase liquid (DNAPL) still present in the source zone. Restoring sites contaminated by chlorinated solvents to regulatory criteria (low parts-per-billion concentrations) within a generation (~20 years) is difficult. Site managers … Continue reading
Type of DNAPL and DNAPL Properties Common DNAPL compounds include materials that have been or are still widely used in industrial and commercial processes, such as the following: chlorinated solvents coal tar creosote heavy petroleum—for example, No. 6 fuel oil products polychlorinated biphenyls (PCBs) pesticides DNAPLs are denser than water, with limited and varying solubility … Continue reading
Sites contaminated by chlorinated solvents present a daunting environmental challenge, especially at sites with dense nonaqueous phase liquid (DNAPL) still present. Restoring sites contaminated by chlorinated solvents to typical regulatory criteria (low parts-per-billion concentrations) within a generation (~20 years) has proven exceptionally difficult, although there have been successes. Site managers must recognize that complete restoration … Continue reading
Integrated site characterization (ISC) is a process for improving the efficiency and effectiveness of characterization efforts at DNAPL sites. It encourages characterization at a sufficient resolution to capture the effects of the heterogeneities that direct contaminant distribution, fate, and transport, and remediation effectiveness, so that an integrated three-dimensional conceptual site map (CSM) can be developed … Continue reading
The Tool Selection Worksheet offers a rapid method of identifying the appropriate tools and information for collecting geologic, hydrologic, and chemical data. Specific tools and techniques are listed in the following categories within the left column of the Tool Selection Worksheet: Geophysics surface geophysics downhole testing Hydraulic testing single well tests cross borehole testing Vapor … Continue reading
Tool List Description Geophysics Surface geophysics 1. Ground penetrating radar locate geologic materials based on reflection of electromagnetic pulse between layer of dielectric properties 2. High resolution seismic reflection seismic reflection for profiling stratigraphic layers to large depths 3. Seismic refraction seismic refraction for 2D interpretation of lithological layer 4. Electrial resistivity tomography indicate broad … Continue reading
Many technologies have been developed for source and plume treatment, all with specific advantages and limitations. Selecting a treatment technology requires evaluating several factors, including technical site features (e.g., geology, hydrogeology, and contaminant levels), regulatory requirements, sustainability, and community stakeholder interests. Traditionally, treatment technologies are applied individually at a site, with the expectation that one … Continue reading
A monitoring approach that relates remedy performance to site-specific SMART functional objectives is a critical element of an integrated strategy. The monitoring approach must include a spatially and temporally sufficient and reliable data set of the remedy performance. An appropriate monitoring program should be dynamic and adjusted to accommodate new data and changing conditions as … Continue reading
