Characterization of chlorinated solvent contamination in limestone using innovative FLUTe® technologies in combination with other methods in a line of evidence approach

Integrity of Clay Till Aquitards to DNAPL Migration: Assessment Using Current and Emerging Characterization Tools

“…The variable saturation conditions are seen as a main challenge with regard to linking the FACT concentrations to possible DNAPL presence. Modeling has recently been used for improved interpretation of FACT concentrations under saturated aquifer conditions (Broholm et al ). For clay till aquitards with more uniform saturation conditions (i.e., below the water table), it may also be possible to better correlate contaminant concentrations in the formation and on the FACT.…”

“…Parker et al () have made detailed field investigations of the matrix diffusion of trichloroethene (TCE) into a glaciolacustrine clayey silt aquitard with DNAPL pooled on top of the formation. Further studies can be aided by current and emerging characterization tools for direct and indirect DNAPL detection such as intact core subsampling with depth‐discrete VOC quantification (e.g., Griffin and Watson ; Parker et al ; Rivett et al ); hydrophobic dye test for direct visual confirmation of DNAPL through dye partitioning into the DNAPL, for example, Sudan IV (Cohen et al ; Griffin and Watson ; Parker et al ; Rivett et al ); Flexible Liner Underground Technolog (FLUTe) liners, for example, impregnated with a hydrophobic dye for visual confirmation of DNAPL upon contact with the liner membrane (Griffin and Watson ; Broholm et al ); membrane interface probe (MIP) for continuous depth‐discrete data obtained by volatilization of contaminants, diffusion through the semi‐permeable membrane and vapor detection by flame ionization detector (FID) (Griffin and Watson ; Adamson et al ; Rivett et al ); organic vapor analysis (OVA) screening of soil samples (headspace) or along intact cores with vapor detection by FID (Griffin and Watson ); partitioning tracers (aqueous or gaseous) with an affinity to be detained in the DNAPL, for example, in the form of partitioning interwell tracer tests (PITTs) (Mariner et al ; Hartog et al ) or soil gas surveys of naturally occurring partitioning tracers such as radon, Rn 222 (Semprini et al ; Höhener and Surbeck ; Schubert et al ); laser‐induced fluorescence (LIF) with continuous depth‐discrete detection of emissions from DNAPL with inherent fluorescent properties, for example, aromatic compounds (Kram et al ; D'Affonseca et al ) or the modified dye‐enhanced LIF (Dye‐LIF) with injection of a hydrophobic dye and subsequent detection of fluorescent changes in the presence of DNAPL, for example, chlorinated solvents (St. Germain et al ); and the Waterloo profiler with depth‐discrete low‐purge collection of groundwater samples (direct push) (Pitkin et al ; Parker et al ). Some of these characterization tools have previously been combined in a multiple‐lines‐of‐evidence approach and compared for DNAPL characterization at sandy industrial sites (Griffin and Watson ; Parker et al ; Rivett et al ).…”

Transport of Tracers and Pesticides Through Fractured Clayey Till: Large Undisturbed Column Experiments and Model‐Based Interpretation

“…Single major fractures/macropores with large apertures may act as rapid transport pathways for the contaminants and dominate the contaminant transport over larger areas. This work highlights the benefit of extensive investigation based on multiple lines of evidence (Broholm et al, 2016;Parker et al, 2019) and on the combination of experimental observation with model-based interpretation, as well as the need of mapping connected hydrological features in clayey till geologies.…”

A Large Undisturbed Column Method to Study Flow and Transport in Macropores and Fractured Media

“…Controlled laboratory experiments in porous media are essential to investigate flow and contaminant transport in the subsurface (Werth et al ; Rolle et al ; Haberer et al , ; Ye et al ). Such experiments often need to include natural geological heterogeneity and preferential flow pathways, for example, fractures, earthworm holes and root channels, because these often control contaminant transport in otherwise low permeability geological units such as clays, shales, and limestones (Grisak et al ; Harrison et al ; Parker et al ; Klint and Gravesen ; Berkowitz ; Jørgensen et al ; Cherry et al ; Rosenbom et al ; Kessler et al , ; Libby and Robbins ; Broholm et al ). Well‐controlled laboratory studies are essential to complement field investigations, because in the latter it can be difficult or even impossible to establish, control, and manipulate boundary conditions.…”