Environmental Remediation Glossary

Definitions for key terms used in in situ remediation, environmental drilling, and groundwater treatment — from IET's expert team with 28+ years of field experience.

A

Activated Persulfate: A chemical oxidation process in which persulfate (S₂O₈²⁻) is activated by a catalyst — most commonly ferric iron (Fe³⁺) — to generate highly reactive sulfate radicals (SO₄•⁻ at 2.60V) and ferrate (Fe⁶⁺ at 2.20V). IET holds U.S. patents on ferric iron-activated persulfate technology (US Patent No. 9,126,245), which simultaneously provides chemical oxidation and sustained secondary bioremediation lasting 2+ years.; See also:ISCO Services IET Patents
Aerobic Bioremediation: A biological treatment process in which naturally occurring or introduced microorganisms degrade organic contaminants using oxygen as the terminal electron acceptor. Aerobic biodegradation is highly effective for petroleum hydrocarbons (BTEX, TPH) but is not effective for chlorinated solvents, which require anaerobic conditions for reductive dechlorination.; See also:Bioremediation
Anaerobic Bioremediation: Biological degradation of contaminants under oxygen-depleted (anaerobic) conditions. This is the primary mechanism for reductive dechlorination of chlorinated solvents such as PCE and TCE. Microorganisms use halogenated compounds as electron acceptors, sequentially removing chlorine atoms. IET stimulates anaerobic conditions through electron donor injection.; See also:Bioremediation
Aquifer: A subsurface geological formation of permeable rock, sediment, or soil that stores and transmits groundwater. Contamination of aquifers by chlorinated solvents, petroleum, and other chemicals is the primary driver of environmental remediation projects. Aquifer characteristics — permeability, porosity, depth, flow direction — govern remediation technology selection.
Attenuation: The natural or engineered reduction of contaminant concentration in soil or groundwater over time and distance from a source. Mechanisms include dilution, dispersion, sorption, volatilization, and biodegradation. Monitored Natural Attenuation (MNA) is sometimes used as a stand-alone remedy or as a component of active remediation programs.

B

Benzene: A volatile aromatic hydrocarbon (C₆H₆) and known human carcinogen commonly found at petroleum release sites including gas stations, refineries, and underground storage tank (UST) sites. Benzene has the lowest MCL (maximum contaminant level) of the BTEX compounds (5 µg/L). IET remediates benzene using ISCO, enhanced bioremediation, and combined approaches.; See also:Petroleum Treatment
Bioaugmentation: The injection of specialized microbial cultures into contaminated groundwater to supplement or introduce populations capable of degrading specific contaminants. Commonly used when native dechlorinating bacteria (such as Dehalococcoides) are absent or insufficient to drive complete reductive dechlorination of TCE/PCE to ethene. IET uses bioaugmentation as part of enhanced ERD programs.; See also:Bioremediation
Bioremediation: The use of living microorganisms to degrade hazardous contaminants in soil and groundwater to less toxic or non-toxic forms. Enhanced bioremediation involves adding nutrients, electron donors, or specialized bacteria to accelerate natural degradation processes. IET specializes in enhanced reductive dechlorination (ERD) for chlorinated solvents and aerobic/anaerobic approaches for petroleum.; See also:Bioremediation Services
Biostimulation: The addition of nutrients, electron donors, or other amendments to stimulate the growth and activity of indigenous microorganisms capable of degrading contaminants. Distinguished from bioaugmentation in that no external microbes are added — existing populations are stimulated. Common amendments include vegetable oil emulsions, lactate, and molasses for anaerobic dechlorination.; See also:Bioremediation
BTEX: An acronym for Benzene, Toluene, Ethylbenzene, and Xylene — a group of volatile aromatic hydrocarbons commonly found in gasoline and crude oil. BTEX compounds are primary contaminants of concern at petroleum release sites. Benzene is classified as a human carcinogen. IET treats BTEX contamination using ISCO (ferric iron-activated persulfate), enhanced bioremediation, and combined approaches.; See also:Petroleum Treatment

C

Chemical Oxidation: See In Situ Chemical Oxidation (ISCO).; See also:Chemical Oxidation
Chlorinated Solvents: Organic compounds containing chlorine atoms, widely used as industrial degreasers and dry cleaning agents. Common examples include PCE (perchloroethylene/tetrachloroethene), TCE (trichloroethylene), 1,1,1-TCA, and DCE (dichloroethene). These compounds are persistent groundwater contaminants that form DNAPLs. They are degraded by reductive dechlorination (anaerobic) or chemical oxidation (ISCO).; See also:Chlorinated Solvents Treatment
Cone Penetration Test (CPT): A geotechnical investigation method in which a cone-tipped probe is pushed into the subsurface at a constant rate to measure soil resistance and friction. CPT provides continuous stratigraphic profiles without soil sample retrieval, enabling rapid site characterization. IET uses CPT with Membrane Interface Probe (MIP) logging for simultaneous contaminant screening.; See also:Geoprobe Services
Contaminant Rebound: The return of contaminant concentrations to pre-treatment levels after an active remediation program ends. Rebound commonly occurs after ISCO when oxidants are exhausted and contaminants continue to dissolve from NAPL, sorbed phases, or back-diffuse from low-permeability zones. IET's patented ferric iron-activated persulfate technology specifically addresses rebound by sustaining secondary bioremediation for 2+ years post-injection.; See also:ISCO Services
Creosote: A complex mixture of PAHs, phenols, and heterocyclic compounds produced from coal tar distillation, historically used as a wood preservative for utility poles and railroad ties. Creosote is a dense, viscous DNAPL contaminant that is particularly persistent in the subsurface. IET specializes in creosote site remediation using ISGS (In Situ Geochemical Stabilization) and EZVI technologies.; See also:NAPL Treatment ISGS

D

DCE (Dichloroethene): A chlorinated solvent that is a degradation daughter product of TCE and PCE during reductive dechlorination. The cis-1,2-DCE isomer is the most commonly observed intermediate. Complete dechlorination continues from DCE to vinyl chloride (VC) and ultimately to non-toxic ethene. DCE "stall" — where dechlorination halts at DCE — is a common site challenge IET addresses through bioaugmentation and geochemical optimization.; See also:Bioremediation
Dehalococcoides (DHC): A genus of anaerobic bacteria that are the primary organisms responsible for complete reductive dechlorination of chlorinated ethenes (PCE → TCE → DCE → VC → ethene). Dehalococcoides require hydrogen as an electron donor and are uniquely capable of dechlorinating vinyl chloride to harmless ethene. IET uses molecular tools to confirm DHC presence and determine if bioaugmentation is needed.; See also:Bioremediation
Direct Push Technology (DPT): A drilling method in which small-diameter sampling tools or probes are advanced into unconsolidated soils by applying hydraulic pushing force, without rotating or removing cuttings. DPT using Geoprobe® or AMS equipment is faster, cheaper, and generates less waste than conventional drilling. IET uses DPT for soil/groundwater sampling, plume delineation, and injection point installation for ISCO and bioremediation programs.; See also:Geoprobe Services Direct Push Drilling
DNAPL: Dense Non-Aqueous Phase Liquid — a contaminant that is denser than water and does not mix with it, causing it to sink through the water table and accumulate in zones of low permeability. Common DNAPLs include chlorinated solvents (PCE, TCE), coal tar, and creosote. DNAPLs are highly persistent subsurface contaminant sources and require specialized treatment technologies such as EZVI, ISGS, or aggressive ISCO.; See also:NAPL Treatment EZVI Technology

E

Electron Donor: A substance that provides electrons in a chemical or biological reaction. In enhanced reductive dechlorination (ERD), organic compounds such as vegetable oil, lactate, or molasses serve as electron donors, providing hydrogen that Dehalococcoides bacteria use to sequentially remove chlorine atoms from PCE/TCE. Selecting the appropriate electron donor type (fast-release vs. slow-release) is critical to ERD program design.; See also:Bioremediation ISCR Services
Enhanced Reductive Dechlorination (ERD): An enhanced bioremediation approach in which fermentable organic substrates (electron donors) are injected into anaerobic groundwater to stimulate reductive dechlorination of chlorinated solvents. ERD drives the sequential degradation PCE → TCE → cis-DCE → vinyl chloride → ethene. IET designs and implements ERD programs using controlled-release substrates and bioaugmentation.; See also:Bioremediation ISCR Services
EZVI (Emulsified Zero Valent Iron): A NASA-patented remediation technology (U.S. Patent No. 6,312,194) consisting of nanoscale zero-valent iron particles suspended in a vegetable oil-water emulsion. The lipophilic outer membrane allows EZVI to mix directly with DNAPL chlorinated solvents, enabling abiotic reductive dechlorination at the source. IET is licensed to apply EZVI and has completed 50+ DNAPL source zone applications nationwide.; See also:EZVI Technology

F

Fenton's Reaction: A chemical process in which hydrogen peroxide (H₂O₂) reacts with ferrous iron (Fe²⁺) to generate highly reactive hydroxyl radicals (OH• at 2.80V) that destroy organic contaminants. Modified Fenton's reagent (also called catalyzed hydrogen peroxide or CHP) is used in ISCO for rapid treatment of petroleum hydrocarbons and some chlorinated solvents. IET practices Fenton-based ISCO as one of several oxidation approaches.; See also:ISCO Services
Ferrate (Fe⁶⁺): A supercharged iron species with an oxidation potential of 2.20V generated when persulfate is activated by ferric iron. Ferrate functions as both an oxidant and a coagulant, directly destroying organic contaminants while simultaneously improving aquifer geochemistry. Ferrate generation is a key feature of IET's patented ferric iron-activated persulfate technology, providing a multi-mechanism oxidation system.; See also:ISCO Services
Free Product: Contaminant present in the subsurface as a separate, non-aqueous phase liquid (NAPL) — either floating on the water table (LNAPL) or sinking below it (DNAPL). Free product recovery typically requires specialized extraction techniques before dissolved-phase treatment can be effective. IET uses ISGS and EZVI to address free product that cannot be practically recovered.; See also:NAPL Treatment EZVI Technology ISGS Technology

G

Geoprobe®: A brand name for direct push drilling equipment manufactured by Geoprobe Systems®. Geoprobe rigs are widely used in environmental drilling for soil/groundwater sampling, monitoring well installation, and remediation injection point installation. IET operates one of the largest fleets of Geoprobe equipment in the eastern United States, with multiple models including the 6610DT, 7822DT, and 8040DT.; See also:Geoprobe Services
Groundwater: Subsurface water occupying the saturated zone below the water table. Groundwater is the primary pathway for contaminant migration from release sites to drinking water wells and surface water receptors. Most IET remediation projects target groundwater contamination by chlorinated solvents, petroleum, or heavy metals.

H

Hexavalent Chromium (Cr VI): A highly toxic, mobile form of the heavy metal chromium found in groundwater at electroplating facilities, tanneries, and sites where chromate compounds were used. Cr(VI) is a human carcinogen regulated at extremely low levels (0.1 µg/L in some states). IET uses ISCR with zero-valent iron to permanently reduce Cr(VI) to the immobile, non-toxic Cr(III) form.; See also:ISCR Services Heavy Metals Treatment
Hollow-Stem Auger: A conventional drilling method in which a helical steel auger with a hollow center is rotated into the ground, allowing soil samples and monitoring wells to be installed through the hollow stem. HSA drilling is commonly used for environmental site investigations and permanent monitoring well installation in unconsolidated soils.; See also:Environmental Drilling
Hydraulic Profiling Tool (HPT): A direct push tool that measures groundwater injection pressure as it is advanced into the subsurface, providing a continuous log of relative hydraulic conductivity versus depth. HPT data is combined with MIP contaminant screening to identify permeable zones where contaminants are concentrated — critical for optimizing injection well screen placement and reagent delivery.; See also:Geoprobe Services
Hydrogen Peroxide (H₂O₂): A strong chemical oxidant used in ISCO, typically at concentrations of 1–10%. When catalyzed by iron (Fenton's reaction), hydrogen peroxide generates hydroxyl radicals that rapidly destroy petroleum hydrocarbons, BTEX, and some chlorinated compounds. H₂O₂ is fast-acting but short-lived in the subsurface due to rapid decomposition, making it best suited for source zone treatment.; See also:ISCO Services

I

In Situ: Latin for "in place." In environmental remediation, in situ refers to treatment methods that destroy or immobilize contaminants underground without excavating or extracting soil and groundwater. In situ approaches avoid hazardous waste disposal costs, minimize site disruption, and can treat deep contamination inaccessible by excavation. All primary IET technologies are in situ.; See also:Remediation Overview
In Situ Chemical Oxidation (ISCO): An in situ remediation technology in which chemical oxidants are injected into contaminated soil and groundwater to chemically destroy organic contaminants in place. Common ISCO oxidants include persulfate, permanganate, hydrogen peroxide, and ozone. IET holds patented ferric iron-activated persulfate technology (U.S. Patent No. 9,126,245) that prevents contaminant rebound through sustained secondary bioremediation.; See also:ISCO Services
In Situ Chemical Reduction (ISCR): An in situ remediation technology using reducing agents — primarily zero-valent iron (ZVI), activated carbon, or chelating amendments — injected into contaminated groundwater to reduce and stabilize metal contaminants (e.g., Cr(VI) → Cr(III)) or reductively dechlorinate chlorinated solvents. ISCR provides long-term reducing conditions lasting 5–10+ years.; See also:ISCR Services
In Situ Geochemical Stabilization (ISGS): IET's proprietary, exclusively licensed technology using modified sodium permanganate (NaMnO₄) solutions for the in situ treatment of non-aqueous phase liquids (NAPL). ISGS reacts with NAPL contaminants to form stable mineral precipitates (birnessite: MnO₂) that physically encapsulate NAPL surfaces, reducing contaminant flux and stabilizing source zones. IET holds the exclusive North American license from Evonik Corporation for ISGS.; See also:ISGS Technology NAPL Treatment
ISCO: See In Situ Chemical Oxidation (ISCO).; See also:ISCO Services
ISCR: In Situ Chemical Reduction — an in situ remediation technology that injects reducing agents (zero-valent iron, dithionite, or ferrous sulfate) into contaminated groundwater to chemically reduce and immobilize contaminants in place. ISCR is the primary treatment for hexavalent chromium (Cr(VI) → Cr(III)), uranium, and other redox-sensitive metals, and also promotes abiotic reductive dechlorination of chlorinated solvents. IET combines ISCR with bioremediation for synergistic treatment of mixed chlorinated solvent and metals sites.; See also:ISCR Services Heavy Metals Treatment

L

LNAPL: Light Non-Aqueous Phase Liquid — a contaminant that is less dense than water and floats on the water table. Common LNAPLs include gasoline, diesel, heating oil, and other petroleum products. LNAPL creates a floating lens of product that continually dissolves into groundwater. IET treats LNAPL-contaminated sites using ISCO, enhanced bioremediation, and combined approaches.; See also:NAPL Treatment

M

MCL (Maximum Contaminant Level): The legally enforceable maximum concentration of a contaminant in public drinking water, as established by the U.S. EPA under the Safe Drinking Water Act. MCLs are used as cleanup standards for many groundwater remediation sites. Common MCLs include TCE at 5 µg/L, PCE at 5 µg/L, and benzene at 5 µg/L.
Membrane Interface Probe (MIP): A direct push downhole tool that continuously screens soil for volatile organic compounds (VOCs) as it is advanced. The MIP heats soil and transfers volatile contaminants across a semipermeable membrane into a carrier gas stream, which is analyzed at the surface by a PID or FID detector. MIP profiling provides continuous depth-specific contaminant distribution data critical for ISCO and bioremediation injection design.; See also:Geoprobe Services
MGP (Manufactured Gas Plant): A facility that historically produced gas from coal for municipal use (1800s–1950s). MGP sites are characterized by complex NAPL contamination including coal tar, creosote, benzene, and PAHs. Hundreds of former MGP sites remain contaminated across the US. IET specializes in MGP site remediation using ISGS for NAPL stabilization and ISCO for dissolved-phase treatment.; See also:NAPL Treatment ISGS
Monitoring Well: A groundwater well installed for the purpose of sampling groundwater to track contaminant concentrations, water table elevations, and remediation performance over time. Monitoring wells are typically 1", 2", or 4" diameter PVC or stainless steel screens installed at specific depths. IET installs monitoring wells as part of site characterization and remediation performance monitoring programs.; See also:Monitor Well Installation
MTBE: Methyl tert-butyl ether — a fuel oxygenate added to gasoline to reduce air emissions. MTBE is highly water soluble and mobile in groundwater, forming large dissolved plumes from small releases. It is resistant to biodegradation under anaerobic conditions. IET treats MTBE-contaminated sites using ISCO (activated persulfate or Fenton's) and enhanced aerobic bioremediation.; See also:Petroleum Treatment

N

NAPL: Non-Aqueous Phase Liquid — a contaminant that does not dissolve in water and forms a separate liquid phase in the subsurface. NAPLs are classified as LNAPL (lighter than water — floats) or DNAPL (denser than water — sinks). NAPLs are persistent groundwater sources that continually dissolve, sustaining plumes for decades. Treating NAPL source zones is essential for achieving site closure.; See also:NAPL Treatment
Natural Attenuation: The reduction of contaminant concentrations in soil and groundwater through natural physical, chemical, and biological processes including dilution, dispersion, sorption, volatilization, and biodegradation. Monitored Natural Attenuation (MNA) uses performance monitoring to demonstrate that natural processes are reducing contamination at acceptable rates. MNA may be used alone or combined with active remediation.

O

ORP (Oxidation-Reduction Potential): A measurement (in millivolts) of the tendency of a solution to accept or donate electrons, indicating the prevailing redox conditions. Positive ORP values indicate oxidizing conditions; negative values indicate reducing conditions. ORP is a critical indicator in bioremediation — anaerobic dechlorination of chlorinated solvents requires strongly reducing conditions (ORP < -100 mV). Geochemists monitor ORP to track bioremediation progress.

P

PAH (Polycyclic Aromatic Hydrocarbon): A class of organic compounds consisting of multiple fused aromatic rings, formed by incomplete combustion of organic matter. PAHs are found at creosote sites, MGP sites, gas stations, and areas affected by wildfire or industrial burning. Many PAHs are carcinogenic. IET treats PAH contamination using ISGS, ISCO (activated persulfate or permanganate), and enhanced bioremediation.; See also:NAPL Treatment
PCE (Perchloroethylene / Tetrachloroethene): A widely used dry cleaning solvent and industrial degreaser (also called PERC or tetrachloroethene, chemical formula C₂Cl₄). PCE is the most common chlorinated solvent at dry cleaner sites and a frequent groundwater contaminant. MCL is 5 µg/L. PCE degrades sequentially under anaerobic conditions: PCE → TCE → DCE → vinyl chloride → ethene. IET treats PCE using ISCO (persulfate/permanganate), ERD bioremediation, and EZVI for DNAPL zones.; See also:Chlorinated Solvents Bioremediation
Permanganate: A common ISCO oxidant (potassium permanganate, KMnO₄, or sodium permanganate, NaMnO₄) effective for oxidizing chlorinated ethenes (TCE, PCE, DCE) and some other organic contaminants. Permanganate is stable and persistent in groundwater, providing extended treatment. It produces manganese dioxide (MnO₂) as a reaction byproduct, which can reduce aquifer permeability if over-applied. IET uses permanganate in both ISCO and ISGS applications.; See also:ISCO Services ISGS
Permeable Reactive Barrier (PRB): A passive in situ treatment technology in which a reactive material (typically zero-valent iron) is placed in a subsurface trench perpendicular to groundwater flow. As contaminated groundwater passes through the barrier, contaminants are treated by reduction/degradation. PRBs require no energy input and provide long-term passive treatment, making them cost-effective for plume management.; See also:ISCR Services
Persulfate: A strong chemical oxidant (S₂O₈²⁻) used in ISCO remediation. When activated (by heat, alkaline conditions, or ferric iron), persulfate generates highly reactive sulfate radicals (SO₄•⁻, 2.60V) that destroy a wide range of organic contaminants. IET holds patented technology for ferric iron-activated persulfate (U.S. Patent No. 9,126,245) that simultaneously generates multiple oxidants and supports sustained secondary bioremediation for 2+ years.; See also:ISCO Services IET Patents
Phase II ESA: A Phase II Environmental Site Assessment — a subsurface investigation conducted to characterize soil and groundwater contamination at a property. Phase II ESAs include soil borings, groundwater sampling, and laboratory analysis to identify, delineate, and quantify contamination. IET provides drilling and sampling services to support Phase II ESAs conducted by environmental consulting firms.; See also:Environmental Drilling
Piezometer: A small-diameter groundwater monitoring point used to measure hydraulic head (water level) at a specific depth. Unlike monitoring wells, piezometers are typically used for water level measurement rather than groundwater sampling. IET installs piezometers as part of hydrogeologic site characterization programs.; See also:Piezometer Installation
Plume: A zone of dissolved contamination that migrates from a contaminant source through groundwater, typically in the direction of groundwater flow. Plume delineation — defining the lateral and vertical extent of dissolved contamination — is a critical site characterization step that guides remediation design. IET uses direct push tools (MIP, HPT) and monitoring wells to characterize contaminant plumes.

R

Reductive Dechlorination: The sequential removal of chlorine atoms from chlorinated solvents by anaerobic bacteria that use the compounds as electron acceptors. The dechlorination sequence for PCE is: PCE → TCE → cis-DCE → vinyl chloride → ethene (non-toxic). Complete dechlorination requires Dehalococcoides bacteria, adequate hydrogen as an electron donor, and strongly reducing geochemical conditions.; See also:Bioremediation
Remediation: The process of treating contaminated soil, groundwater, or sediment to reduce contaminant concentrations to acceptable levels that protect human health and the environment. Remediation technologies include in situ chemical oxidation (ISCO), enhanced bioremediation, in situ chemical reduction (ISCR), NAPL treatment, and ex situ approaches such as pump-and-treat.; See also:Remediation Services

S

Soil Vapor Extraction (SVE): An ex situ remediation technology that removes volatile organic compounds (VOCs) from the unsaturated (vadose) zone by applying vacuum to extraction wells. SVE is effective for relatively permeable soils contaminated with high-volatility compounds such as chlorinated solvents and gasoline. IET installs soil vapor points and SVE extraction wells as part of site investigation and remediation programs.; See also:Environmental Drilling
Source Zone: The area of highest contamination where residual or free-phase NAPL is present. Source zones continuously dissolve into groundwater, sustaining dissolved-phase plumes downgradient. Treating source zones — using ISCO, ISGS, EZVI, or excavation — is essential for achieving plume containment and site closure. IET specializes in aggressive source zone treatment using multiple technologies.
SPT (Standard Penetration Test): A geotechnical field test used to evaluate subsurface soil resistance by driving a split-spoon sampler into the ground with a standardized weight dropped a set distance. SPT "N values" are used for geotechnical design of foundations, retaining walls, and slopes. IET performs SPT testing for geotechnical investigations.; See also:Geotechnical Drilling
Sulfate-Reducing Bacteria (SRB): Anaerobic microorganisms that use sulfate (SO₄²⁻) as a terminal electron acceptor, reducing it to sulfide (H₂S). SRBs play an important role in natural attenuation and can contribute to reductive dechlorination at some sites. IET's ferric iron-activated persulfate technology generates sulfate that supports SRB activity for sustained long-term bioremediation after ISCO treatment.

T

TCE (Trichloroethylene / Trichloroethene): A common chlorinated solvent (CHCl=CCl₂) widely used as a metal degreaser and in dry cleaning. TCE is one of the most prevalent groundwater contaminants in the United States, listed as a probable human carcinogen. The MCL is 5 µg/L. IET remediates TCE-contaminated sites using ISCO (ferric iron-activated persulfate, permanganate), ERD bioremediation, ISCR (ZVI), and EZVI for DNAPL zones.; See also:Chlorinated Solvents ISCO Services
Terminal Electron Acceptor (TEA): In microbial metabolism, the compound that accepts electrons at the end of the electron transport chain, enabling energy generation. In aerobic environments, oxygen is the TEA. Under anaerobic conditions, microorganisms use nitrate, iron, sulfate, and carbon dioxide as TEAs in sequence. In enhanced bioremediation, understanding TEA availability is critical for predicting degradation rates and selecting electron donor amendments.
Total Petroleum Hydrocarbons (TPH): A broad measure of the concentration of a range of petroleum-derived hydrocarbon compounds in soil or groundwater, expressed as a sum. TPH encompasses hundreds of individual compounds including BTEX, alkanes, cycloalkanes, and PAHs. TPH measurements are used to characterize petroleum release sites and track remediation performance.; See also:Petroleum Treatment

V

Vadose Zone: The unsaturated zone of soil above the water table, where pore spaces contain both air and water. Contaminants released at the surface migrate through the vadose zone before reaching groundwater. NAPL in the vadose zone can serve as a continuing source of groundwater contamination. Soil vapor extraction (SVE) and bioventing are common vadose zone treatment technologies.
Vapor Intrusion: The migration of volatile organic compounds (VOCs) from contaminated soil or groundwater through the vadose zone and building foundation into indoor air. Vapor intrusion can create health risks for building occupants at concentrations far below those that would affect groundwater users. IET investigates vapor intrusion pathways using soil vapor probes and direct push sampling.; See also:Geoprobe Services
Vinyl Chloride (VC): A chlorinated solvent (CH₂=CHCl) and known human carcinogen that is an intermediate daughter product of PCE/TCE reductive dechlorination. Vinyl chloride is more toxic than its parent compounds and has an MCL of 2 µg/L. VC accumulation ("VC stall") at a site indicates incomplete dechlorination. IET addresses VC stall through bioaugmentation with Dehalococcoides cultures or ISCO for direct destruction.; See also:Bioremediation

Z

Zero-Valent Iron (ZVI): Elemental iron (Fe⁰) used in both ISCR and EZVI remediation technologies. ZVI reacts with chlorinated solvents through reductive dechlorination: Fe⁰ + RCl + H⁺ → Fe²⁺ + RH + Cl⁻. ZVI also generates hydrogen gas that supports anaerobic dechlorinating bacteria. IET uses ZVI in ISCR injection programs, permeable reactive barriers, and as the active ingredient in EZVI emulsions for DNAPL treatment.; See also:ISCR Services EZVI Technology

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