Valence state: The combining capacity of an atom or radical determined by the number of electrons that it will lose, add, or share when it reacts with other atoms.
free product: A NAPL found in the subsurface in sufficient quantity that it can be partially recovered by pumping or gravity drain.
aerobic: Direct aerobic metabolism involves microbial reactions that require oxygen to go forward. The bacteria uses a carbon substrate as the electron donor and oxygen as the electron acceptor. Degradation of contaminants that are susceptible to aerobic degradation but not anaerobic often ceases in the vicinity of the source zone because of oxygen depletion. This can sometimes be reversed by adding oxygen in the form of air (air sparging, bioventing), ozone, or slow oxygen release compound (e.g., ORC(r)).
Aerobic dechlorination may also occur via cometabolism where the dechlorination is incidental to the metabolic activities of the organisms. In this case, contaminants are degraded by microbial enzymes that are metabolizing other organic substrates. Cometabolic dechlorination does not appear to produce energy for the organism. At pilot- or full-scale treatment, cometabolic and direct dechlorination may be indistinguishable, and both processes may contribute to contaminant removal. For aerobic cometabolism to occur there must be sufficient oxygen and a suitable substrate which allows the microbe to produce the appropriate enzyme. These conditions may be present naturally but often in the presence of a source area oxygen and a substrate such as methane or propane will need to be introduced.
Adapted from US. EPA 2006 Engineering Issue: In Situ and Ex Situ Biodegradation Technologies for Remediation of Contaminated Sites
anaerobic: Direct anaerobic metabolism involves microbial reactions occurring in the absence of oxygen and encompasses many processes, including fermentation, methanogenesis, reductive dechlorination, sulfate-reducing activities, and denitrification. Depending on the contaminant of concern, a subset of these activities may be cultivated. In anaerobic metabolism, nitrate, sulfate, carbon dioxide, oxidized metals, or organic compounds may replace oxygen as the electron acceptor.
Anaerobic dechlorination also may occur via cometabolism where the dechlorination is incidental to the metabolic activities of the organisms. In this case, contaminants are degraded by microbial enzymes that are metabolizing other organic substrates. Cometabolic dechlorination does not appear to produce energy for the organism. At pilot- or full-scale treatment, cometabolic and direct dechlorination may be indistinguishable, and both processes may contribute to contaminant removal.
Quoted from US. EPA 2006 Engineering Issue: In Situ and Ex Situ Biodegradation Technologies for Remediation of Contaminated Sites
architecture: "Architecture" refers to the physical distribution of the contaminant in the subsurface. Residuals that take the form of long thin ganglia or small dispersed globules provide a larger surface area that will dissolve much faster than if the same amount of liquid were concentrated in a competent pool.
Sources: For purposes of this discussion, a DNAPL source zone includes the zone that encompasses the entire subsurface volume in which DNAPL is present either at residual saturation or as "pools" of accumulation above confining units. In addition, the DNAPL source zone includes regions that have come into contact with DNAPL that may be storing contaminant mass as a result of diffusion of DNAPL into the soil or rock matrix.
source zone: For purposes of this discussion, a DNAPL source zone includes the zone that encompasses the entire subsurface volume in which DNAPL is present either at residual saturation or as "pools" of accumulation above confining units. In addition, the DNAPL source zone includes regions that have come into contact with DNAPL that may be storing contaminant mass as a result of diffusion of DNAPL into the soil or rock matrix.
focal ulceration: The process or fact of a localized area being eroded away.
metaplasia of the glandular stomach: A change of cells to a form that does not normally occur in the tissue in which it is found.
hyperplasia of the glandular stomach: A condition in which there is an increase in the number of normal cells in a tissue or organ.
histiocytic: Degenerative.
duodenum: First part of the small intestine.
microcytic: Any abnormally small cell.
squamous cell papillomas: A small solid benign tumor with a clear-cut border that projects above the surrounding tissue.
squamous cell carcinomas: Cancer that begins in squamous cells-thin, flat cells that look under the microscope like fish scales. Squamous cells are found in the tissue that forms the surface of the skin, the lining of hollow organs of the body, and the passages of the respiratory and digestive tracts. Squamous cell carcinomas may arise in any of these tissues.
jejunum: The middle portion of the small intestine, between duodenum and ileum. It represents about 2/5 of the remaining portion of the small intestine below duodenum.
ileum: The distal and narrowest portion of the small intestine.
squamous: Flat cells that look like fish scales.
metaplasia: A condition in which there is a change of one adult cell type to another similar adult cell type.
ossification: The process of creating bone, that is of transforming cartilage (or fibrous tissue) into bone.
clastogenesis: Any process resulting in the breakage of chromosomes.
neoplastic: Abnormal and uncontrolled growth of cells.
ulceration: The process or fact of being eroded away.
leucocytosis: An elevation of the total number of white cells in blood.
neutrophils: A type of white blood cell.
chromodulin: A small protein that binds four trivalent chromium ions.
biomagnification: The increased accumulation and concentration of a contaminant at higher levels of the food chain; organisms higher on the food chain will have larger amounts of contaminants than those lower on the food chain, because the contaminants are not eliminated or broken down into other chemicals within the organisms.
exencephaly: Cerebral tissue herniation through a congenital or acquired defect in the skull.
everted viscera: Rotated body organs in the chest cavity.
To Be Considered: Documents, such as federal or state guidances, that are not legally binding but may be relevant to the topic in question.
gaining: A gaining surface water body is one where groundwater flows into it.
losing: A surface water body is losing when there is a permeable sediment bed that is not in contact with the groundwater allowing the surface water to seep through it.
fluvial: Of or pertaining to flow in rivers and streams.
lacustrine: Of or pertaining to a lake as in lacustrine sediments—sediments at the bottom of a lake.
lipid: Any class of fats that are insoluble in water.
lipophilic: Able to dissolve in lipids—in this case fatty tissue.
organelles: A part of a cell such as mitochondrion, vacuole, or chloroplast that plays a specific role in how the cell functions and membranes.
RfD: The RfD is an estimate of a daily exposure of the human population (including sensitive sub-groups) to a substance that is likely to be without "the appreciable risk of deleterious effects during a lifetime." An RfD is expressed in units of mg/kg-day.
autonomic: That part of the nervous system that controls non-conscious actions such as heart rate, perspiration and digestion.
ataxia: Lack of muscle coordination.
funnel-and-gate configuration: A system where low-permeability walls (the funnel) placed in the saturated zone direct contaminated ground-water toward a permeable treatment zone (the gate)
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In Situ Characterization of NAPL with TarGOST® Laser Induced Fluorescence
The TarGOST®, a modified version of the Rapid Optical Screening Tool (ROST®), uses visible wavelength fluorescence spectroscopy to yield a monotonic response in the presence of coal tar in soil. The TarGOST® is capable of logging 300 to 500 ft/day at 10 to 20 separate probing locations.
Case Study: Confirmation of TarGOST Laser-Induced Fluorescence DNAPL Delineation with Soil Boring Data
M.B. Okin, S.M. Carroll, W.R. Fisher, and R.W. St. Germain. Land Contamination & Reclamation, Vol 14 No 2, p 502-507, 2006
The TarGOST® was used at a manufactured gas plant (MGP) site to provide a real-time, semi-quantitative assessment of the extent of coal tar contamination in an investigation that took place on land using a cone penetrometer test (CPT) rig and on water using a barge with a Geoprobe® to assess sediment contamination. Confirmation sampling agreed with the TarGOST® results. The investigation showed a strong correlation between the presence of coal tar as detected by TarGOST® and the presence of sandy layers in the subsurface. The investigation also indicated the presence of coal tars at some distance from source areas in thin, highly permeable seams found in lower permeability units. Without the use of the direct push equipment and the TarGOST® probe, these seams most likely would have been missed.
This report describes a characterization assessment framework for MGP DNAPLs. The report confirms the ability of laser fluorescence technology (TarGOST®) to vertically and horizontally delineate the extent of subsurface DNAPLs.
Gowanus Canal Superfund Site. IV: Delineation of Potentially Migrating NAPL Layers for ISS Treatment
Gee, G.L., D.G. Grubb, J.L. Gentry, C.D. Tsiamis, and J. Hess.
Journal of Hazardous, Toxic, and Radioactive Waste 26(3)(2022)
This paper presents the decision-making strategy applied to select areas to implement ISS to a depth of 5 ft into the native sediments at the Gowanus Canal Superfund site after dredging the overlying soft sediments in remedial target areas (RTAs)-1 and -2. Historic operation of three manufactured gas plants resulted in NAPL impacts. ISS target areas were developed primarily from in-canal Tar-specific Green Optical Screening Tool (TarGOST) analysis of sediments at a 2-in. (5 cm) layer resolution and an empirical correlation relating the TarGOST percent reference emitter response to the NAPL pore fluid saturation (PFS) in the cores, and the measured NAPL PFS threshold above which NAPL was potentially mobile. A volume accommodation model (VAM) evaluated the ability of various individual NAPL PFS exceedances and their associated layer thicknesses in the sediment to trigger a PFS exceedance above the threshold value of the entire overlying horizon, resulting in NAPL breakthrough from as deep as 10 ft into the native sediment. The output from the VAM was integrated with ArcGIS spatial mapping and visualization tools to generate Thiessen polygons that indicated the areas having overall NAPL exceedances. Mobile NAPL areas were identified and effectively targeted for ISS, totaling 82,798 and 227,297 ft2 (7,692 and 21,117 m2) in RTA-1 and -2, respectively, or 15,227 and 49,843 yd3 (11,642 and 38,128 m3) based on the ISS mass thickness. View abstract
In Situ Characterization of NAPL with TarGOST at MGP Sites
R. St. Germain, S. Adamek, and T. Rudolph. Land Contamination & Reclamation, Volume 14, Number 2, 2006, pp. 573-578(6)
Site characterization of former MGP sites where coal tars and associated chemicals are found can be challenging. The tendency for coal tar to sink into the subsurface following the path of least resistance can require a large number of discrete sample locations to properly delineate it; however, the number of discrete samples that can be subjected to laboratory analysis is restricted by the high cost of standard methods. The TarGOST®, an alternative to conventional methods, is a direct push probe that uses a laser-induced fluorescence (LIF) instrument for contaminant detection. As it is pushed into the subsurface, this tool is specifically designed to detect coal tars.
Using TarGOST® to Delineate the Presence of Coal Tar in Subsurface Soils
Electric Power Research Institute (EPRI), Palo Alto, CA. Report No 1012131, Aug 2005
The TarGOST® LIF profiling method was applied at the Former Hackensack Gas Works site and adjacent property. EPRI and PSEG SC evaluated the results and effectiveness of the tool to locate coal tar in the subsurface due to the availability of recently collected site characterization information and the need to characterize the presence of coal tar that appeared to have migrated from the site onto an adjacent property. This evaluation was accomplished by advancing the TarGOST® technology at as many boring locations as possible within a 5-day field period to build a robust data set. Selected TarGOST® probe locations were drilled both to compare soil conditions visually and to evaluate soils using the LIF technology. Information gathered during this technology evaluation program was to be used in the evaluation of remedial action objectives for the site. The investigators first used TarGOST® to characterize general subsurface conditions at the site and then to delineate the extent of coal tar formerly observed in specific areas of the site and to determine if coal tar exists beyond those points. Conventional DPT was used to collect soil cores for comparison with and evaluation of the effectiveness of TarGOST®. When the data were evaluated, the technology was found to be an effective coal tar characterization and delineation tool. TarGOST® is useful to site managers in the following applications: characterizing and delineating the extent of coal tar; limited differentiation between separate, unique sources of coal tar within a study area; better geologic characterization when coupled with conventional soil borings; and rapid screening of large areas before collecting confirmatory delineation samples.
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