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Site Type: Manufactured gas plants and coal gasification
Manufactured gas has been produced as a fuel source from coal and oil since the early 1800s. Typically, coal or oil is heated and the resulting volatilized gases are distilled to produce natural gas. Depending on the process design, various by-products can be recovered, including anthracene, benzene, cresol, naphthalene, paraffin, phenol, toluene, and xylenes. Waste products from manufactured gas operations include coal fines, coal tar, cyanide salts, hydrogen sulfide gas, ammonia, and wastewater. Leakage and spillage from storage drums or tanks may contaminate surface and subsurface soils, sediments, surface water, and groundwater.
Contaminant groups that are associated with this site type are listed below.
Fuels
Fuels are a general class of chemicals created by refining and manufacturing petroleum or natural gas for use in combustion processes to generate heat or other energy. Fuels include nonhalogenated VOCs, nonhalogenated SVOCs, or both. Sites where fuel contamination may be found include aircraft, storage and service areas, burn pits, chemical disposal areas, contaminated marine sediments, disposal wells and leach fields, firefighting training areas, hangars and aircraft maintenance areas, landfills and burial pits, leaking storage tanks, solvent degreasing areas, surface impoundments, and vehicle maintenance areas.
Typical Contaminants
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Metals and metalloids
Metals are one of the three groups of elements distinguished by their ionization and bonding properties, along with metalloids and nonmetals. Metals have certain characteristic physical properties: they are usually shiny, have a high density, are ductile and malleable, usually have a high melting point, are usually hard, and conduct electricity and heat well. Metalloids have properties that are intermediate between those of metals and nonmetals. There is no unique way of distinguishing a metalloid from a true metal, but the most common way is that metalloids are usually semiconductors rather than conductors. Locations where metals and metalloids may be found include artillery and small arms impact areas, battery disposal areas, burn pits, chemical disposal areas, contaminated marine sediments, disposal wells and leach fields, electroplating and metal finishing shops, firefighting training areas, landfills and burial pits, leaking storage tanks, radioactive and mixed waste disposal areas, oxidation ponds and lagoons, paint stripping and spray booth areas, sand blasting areas, surface impoundments, and vehicle maintenance areas.
Typical Contaminants
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Nonhalogenated SVOCs
No halogen (fluorine, chlorine, bromine, or iodine) is attached to a nonhalogenated SVOC. Locations where nonhalogenated SVOCs may be found include burn pits, chemical manufacturing plants and disposal areas, contaminated marine sediments, disposal wells and leach fields, electroplating and metal finishing shops, firefighting training areas, hangars and aircraft maintenance areas, landfills and burial pits, leaking storage tanks, radioactive and mixed waste disposal areas, oxidation ponds and lagoons, pesticide and herbicide mixing areas, solvent degreasing areas, surface impoundments, and vehicle maintenance areas, and wood preservation sites.
Typical Contaminants
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Nonhalogenated VOCs
No halogen (fluorine, chlorine, bromine, or iodine) is attached to a nonhalogenated VOC. Locations where nonhalogenated VOCs may be found include burn pits, chemical manufacturing plants and disposal areas, contaminated marine sediments, disposal wells and leach fields, electroplating and metal finishing shops, firefighting training areas, hangars and aircraft maintenance areas, landfills and burial pits, leaking storage tanks, radioactive and mixed waste disposal areas, oxidation ponds and lagoons, paint stripping and spray booth areas, pesticide and herbicide mixing areas, solvent degreasing areas, surface impoundments, and vehicle maintenance areas.
Typical Contaminants
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Investigation technologies associated with this site type are listed below. Click on the name of the technology to view details.
Amperometric and Galvanic Cell Sensor
Amperometric and galvanic cell sensors involve ambient air quality monitoring of VOCs. Amperometric and galvanic cell sensors measure an electrochemical response when the sensor comes into contact with the analyte of interest. An internal pump draws an air sample into the analyzer. Each probe contains a sensor that is specifically sensitive to a particular gas or vapor. These sensors typically consist of electrodes in contact with an electrolyte-saturated insulator. Selective membranes allow the gas of interest to enter the insulator, and redox reaction on the sensing-electrode surface generates a current that is proportional to the analyte concentration. When an analyte is present, it will absorb to the thin-film sensor, which undergoes a change in electrical resistance proportional to the mass of analyte absorbed onto its surface. This change is measured and converted to a vapor concentration that is displayed on the readout of the analyzer. (Learn more ...)
Anodic Stripping Voltammetry
Anodic stripping voltammetry (ASV) is an electrochemical technique in which information about an analyte is derived from measurement of current as a function of applied potential. The measurement is performed in an electrochemical cell under polarizing conditions on a working electrode, which is normally a mercury or gold film-coated, glassy carbon electrode. Analysis involves a two-step process consisting of electrolysis and stripping. The analyte of interest is reduced and collected at the working electrode and then stripped off and measured. The reduction step is much longer than the stripping step, and the increase in the signal to noise allows low-concentration solutions to be measured. The advantage of ASV is the ability to distinguish between different oxidation states of the same metal. Anodic stripping voltammetry, along with similar potentiometric techniques (including constant current stripping voltammetry and cathodic stripping voltammetry), has been used for measurement of trace levels of a variety of metals. (Learn more ...)
Atomic Absorption Spectroscopy
Atomic absorption (AA) spectroscopy involves the absorption of radiant energy by neutral atoms in the gaseous state. Since samples are usually liquids or solids, the atoms or ions in the analyte must be vaporized in a flame or graphite furnace. The atoms absorb ultraviolet or visible light and make transitions to higher electronic energy levels. The analyte concentration is measured from the amount of absorption. More sophisticated instruments can have more than one channel for simultaneous measurement of more than one element. Multi-element sequential instruments can be programmed to automatically determine chosen elements sequentially. (Learn more ...)
Catalytic Surface Oxidation
Catalytic surface oxidation is a combustible gas indicator. Instruments can be used in the immediate environment or can draw samples from remote areas through sampling lines or probes. Catalytic surface oxidation devices operate in similar fashion to explosimeters. (Learn more ...)
Chemical Colorimetric Kits
Chemical colorimetric kits are self-contained portable kits for analyzing soil or water samples for the presence of a variety of inorganic and organic compounds. These tests require no instrumentation and can be performed in the field with minimal training. They should only be used as an indication or screening device and are safe for thermally sensitive compounds. Colorimetry involves mixing of reagents of known concentrations with a test solution in specified amounts that result in chemical reactions in which the absorption of radiant energy (color of the solution) is a function of the concentration of the analyte of interest. At the simplest level, concentrations can be estimated with visual comparators. (Learn more ...)
Cone Penetrometer Testing
Cone Penetrometer Testing (CPT) is a direct-push technology that uses hydraulic pressure to advance sampling devices and geotechnical and analytical sensors into the subsurface. Used for approximately the last 50 years for geotechnical applications, its use for site characterization is relatively new. (Learn more ...)
Detector Tubes
Detector tubes contain a reagent located on absorbing material that is specifically sensitive to a particular vapor or gas. Operation generally involves inserting the tube into a hand-held pump. As the handle of the pump is pulled, ambient air is drawn inside the tube where it contacts the reagent and the reagent then changes color. The color will move up the tube to indicate the concentration (indicated by a calibration mark on the tube). (Learn more ...)
Electrical Conductivity Probe
An Electrical Conductivity (EC) Probe is a direct-push technology that measures electrical properties in soil to determine relative vertical variations in lithology. (Learn more ...)
Electromagnetic Conductivity
Electromagnetic Conductivity (EM) is a surface geophysics technology that measures the conductivity of the subsurface, which includes soil, groundwater, rock, and objects buried in the ground. (Learn more ...)
Explosimeter
Explosimeters are used to verify flammable gas concentration in the atmosphere. Instruments can be used in the immediate environment or can draw samples from remote areas through sampling lines or probes. The instrument operates by the catalytic action of a heated filament in contact with combustible gases. The filament is heated to operating temperature by passage of an electrical current. When the gas sample contacts the heated filament, combustion on the surface raises the temperature in proportion to the quantity of combustibles in the sample. A sensor measures the change in electrical resistance caused by the temperature increases. A signal is processed and displayed as the percentage of the combustible gas present to the total required to reach the lower explosive limit (LEL) or the percent combustible gas by volume. (Learn more ...)
Fiber Optic Chemical Sensors
Fiber optic chemical sensors (FOCS) operate by transporting light by wavelength or intensity to provide information about analytes in the environment surrounding the sensor. The environment surrounding a FOCS is usually air or water. FOCS can be categorized as intrinsic or extrinsic. Extrinsic FOCS simply use an optical fiber to transport light. An example is the laser induced fluorescence (LIF) cone penetrometer. The optical fiber is only a conduit for the laser induced fluorescence to be transported to an uphole detector. In contrast, intrinsic FOCS use the fiber directly as the detector. A portion of the optical fiber cladding is removed and replaced with a chemically selective layer. The sensor is then placed directly into the medium to be analyzed. Interaction of the analyte with the chemically selective layer creates a change in absorbance, reflectance, fluorescence, or light polarization. The optical change is then detected by measuring changes in the light characteristic carried by the optical fiber. (Learn more ...)
Field Bioassessment
Field bioassessments provide an indication of the potential for ecological risk (or lack of) that can be used to: (1) estimate the likelihood that ecological risk exists; (2) identify the need for site-specific data collection efforts; and (3) focus site-specific ecological risk assessments where warranted. Initial screening-level assessments are not designed or intended to provide definitive estimates of actual risk or generate cleanup goals, and are not based on site-specific assumptions. Rather, their purpose is to assess the need to conduct a detailed ecological risk assessment for a particular site. (Learn more ...)
Field-Portable X-Ray Fluorescence
Field portable X-ray fluorescence (FPXRF) is a hand-held device for simultaneously measuring a number of metals in various media. FPXRF units that run on battery power and use a radioactive source were developed for use in analysis for lead-based paint and now are accepted as a stand-alone technique for analysis of lead. In response to the growing need for field analysis of metals at hazardous waste sites, many of these FPXRF units have been adapted for use in the environmental field. The field-rugged units use analytical techniques that have been developed for analysis of numerous environmental contaminants in soils. They provide data in the field that can be used to identify and characterize contaminated sites and guide remedial work, among other applications. In addition, FPXRF units are now manufactured with non-radioactive sources, making them available for use nationwide without having to address radioactive source use permitting requirements. (Learn more ...)
Flame Ionization Detector
Portable flame ionization detector (FID) instruments detect compounds by using a sampling pump to feed air into a mixing chamber. The mixture is ignited as it passes over a pure hydrogen flame that breaks down the organic molecules and produces ions (atoms or molecules that have gained or lost electrons and thus have a net positive or negative charge). The ions gather on a collection plate, where a current is generated as a result of the high voltage applied across the detector and the organic ions and electrons present in the gas. The magnitude of the current is proportional to the concentration of organic vapors in the gas. FIDs are also commonly used as detectors in portable gas chromatographs and have several advantages over photoionization detectors (PIDs), including a wider measuring range and response to all hydrocarbons and methane. In addition, FIDs do not give false positive readings to water vapor. (Learn more ...)
Fluorescence Spectrophotometry
Spectrophotometry encompasses a number of techniques involving measurement of the absorption spectra of narrow band widths of radiation. A simple spectrophotometer consists of (1) a radiation source; (2) a monochromator, containing a prism or grating that disperses the light so that only a limited wavelength or frequency range is allowed to irradiate the sample; and (3) a detector that measures the amount of light transmitted by the sample. (Learn more ...)
Fourier Transform Infrared Spectroscopy
Fourier transform infrared (FTIR) spectroscopy measures the absorption caused by infrared active molecules. This technique involves generation of a light beam over a range of wavelengths in the near-infrared (IR) portion of the spectrum. The beam passes through a parcel of atmosphere in which chemical species absorb IR radiation at characteristic wavelengths. The beam is reflected directly back on itself to the receiver/transmitter. The received spectrum is compared with a library spectrum for each chemical compound of interest so that the compounds present can be identified and qualified. Data are analyzed using a computer and a software package. (Learn more ...)
Free Product Sensors
Free product sensors are designed to give an accurate measurement of liquids lighter than water. A 1.5-inch (38-millimeter) diameter probe includes a highly visible light with an audible signal to indicate the presence of water and light immiscible liquids. (Learn more ...)
Fuel Fluorescence Detector
A Fuel Fluorescence Detector (FFD) is a direct push ultraviolet fluorescence (UVF) probe that is used primarily for investigating fuel impacts. The probe contains a UV lamp that causes polycyclic aromatic hydrocarbons (PAHs) in fuels to fluoresce. Fluorescence is captured by the probe and converted to an electronic signal which corresponds to concentration. (Learn more ...)
Gas Chromatography/ Mass Spectrometry
Coupling mass spectrometers with gas chromatography (GC) systems allows separation and subsequent determination of components of highly complex mixtures with a high degree of certainty. Similar compounds may be retained for different lengths of time on the GC column, allowing separate identification and quantitation, even if the two compounds, or fragments of compounds, have similar mass to charge ratios. Retention time thus provides a secondary source of identification. Recently, manufacturers of mass spectrometers, particularly spectrometers coupled with GC systems, have significantly reduced their overall size and have increased durability. These changes allow what was once a laboratory bench-top instrument to be portable (or transportable), and sufficiently rugged to perform field analysis. (Learn more ...)
Ground Penetrating Radar
Ground penetrating radar (GPR) is most commonly used for locating buried objects (such as tanks, pipes, and drums); mapping the depth of the shallow water table; identifying soil horizons and bedrock subsurface; mapping trench boundaries; delineating karst features and the physical integrity of manmade earthen structures; and selecting locations for installation of suction samplers in the vadose zone. (Learn more ...)
Hydraulic Profiling Tool
The Hydraulic Profiling Tool (HPT) is a probe that measures the relative hydraulic properties of unconsolidated subsurface deposits. (Learn more ...)
Immunoassay Colorimetric Kits
Immunoassay (IA) colorimetric kits involve field screening of individual contaminants. IA technology relies on an antibody that is developed to have a high degree of sensitivity to the target compound. This antibody's high specificity is coupled within a sensitive colorimetric reaction that provides a visual result. The intensity of the color formed is inversely proportional to the concentration of the target analyte in the sample. The absence or presence is determined by comparing the color developed by a sample of unknown concentration with the color formed with the standard containing the analyte at a known concentration. (Learn more ...)
Inductively Coupled Plasma-Atomic Emission Spectroscopy
Atomic emission spectroscopy (AES) measures the optical emission from excited atoms to measure the analyte concentration. Analyte atoms in solution are aspirated into the excitation region where they are desolvated, vaporized, and atomized by a flame, discharge, or plasma. High-temperature atomization sources are used to promote the atoms into high energy levels causing them to decay back to lower levels by emitting light. Inductively coupled plasma (ICP) is a very high temperature (7,000 to 8,000 °K) excitation source that efficiently desolvates, vaporizes, excites, and ionizes atoms. The standard ICP-AES instrument is a radial configuration. Recently introduced models have an axial configuration, which can achieve lower detection limits. Each configuration has advantages and disadvantages; radial configurations have a proven track record but higher detection limits, while axial configurations have lower detection limits but may not be able to reproduce results as consistently. (Learn more ...)
Infrared Spectroscopy
Infrared (IR) spectroscopy has been an established bench-top laboratory analytical technique for many years. It identifies and quantitates compounds through the use of their IR absorption spectra. Another use of the IR spectra is found with recently developed video cameras. These cameras use IR absorption to image the absorbing compounds on a video tape. The image appears as a cloud on the video and is used to monitor vapor behavior, but the instrument does not identify or quantitate the individual compounds. (Learn more ...)
Ion Chromatography
Ion chromatography is a form of liquid chromatography that uses ion-exchange resins to separate atomic or molecular ions based on their interaction with the resin. Its greatest utility is for analysis of anions when there are no other rapid analytical methods. Most ion-exchange separations are done with pumps and nonmetallic columns. The column packing for ion chromatography consists of ion-exchange resins bonded to inert polymeric particles (typically 10 millimeter diameter). The cation-exchange resin for cation separation is usually a sulfonic or carboxylic acid. The anion-exchange resin for anion separation is usually a quaternary ammonium group. Most ion chromatography instruments use two mobile phase reservoirs containing buffers of different pH, and a programmable pump that can change the pH of the mobile phase during the separation. Ions in solution can be detected by measuring the conductivity of the solution. In ion chromatography, the mobile phase contains ions that create background conductivity, making it difficult to measure the conductivity caused only by the analyte ions as they exit the column. This problem can be greatly reduced by selectively removing the mobile phase ions after the analytical column and before the detector. Converting the mobile phase ions to a neutral form or removing them with an eluent suppressor, which consists of an ion-exchange column or membrane, alleviates this problem. (Learn more ...)
Ion Mobility Spectrometer
Ion mobility spectrometry (IMS) is a technique used to detect and characterize organic vapors in air. Ion mobility spectrometry analysis is based on analyte separations resulting from ionic mobilities rather than ionic masses. A sampling pump draws air through a semipermeable membrane, which is selected to exclude or attenuate possible interferents. The sample is ionized in a reaction region through interaction with a weak plasma of positive and negative ions produced by a radioactive source. A shutter grid allows periodic introduction of the ions into a drift tube, where they separate based on charge, mass, and shape with the arrival time recorded by a detector. The identity of the molecules is determined using a computer to match the signals to IMS signatures held in memory. If the IMS signature is known, it is also possible to program the instrument to detect specific compounds of interest. IMS operates at atmospheric pressure, a characteristic that has practical advantages over mass spectrometry, including smaller size, lower power requirements, less weight, and ease of use. (Learn more ...)
Ion Trap Mass Spectrometry
Ion trap mass spectrometry determines the masses of atoms or molecules found in a solid, liquid, or gas, particularly VOCs. It uses three electrodes to trap ions in a small volume. The mass analyzer consists of a ring electrode separating two hemispherical electrodes. A mass spectrum is obtained by changing the electrode voltages to eject the ions from the trap. The advantages of the ion trap mass spectrometer include compact size and the ability to trap and accumulate ions to increase the signal-to-noise ratio of a measurement. (Learn more ...)
Laser-Induced Fluorescence (LIF) Probe (UVOST, ROST, TarGOST)
Laser-induced Fluorescence (LIF) is a method for real-time, in situ, field screening of hydrocarbons in subsurface soils and groundwater. The technology is intended to provide highly detailed, qualitative to semi-quantitative information about the distribution of subsurface petroleum contamination. LIF sensors are deployed as part of integrated, mobile CPT systems that are operated by highly trained technicians familiar with the technology and its application. Examples of LIF probes include UltraViolet Optical Screening Tools (UVOST), Rapid Optical Screening Tools (ROST), and Tar Specific Green Optical Screening Tools (TarGOST). (Learn more ...)
Magnetometry
Magnetometry is a surface geophysics technology that is used for locating subsurface iron, nickel, cobalt and their alloys, which are typically referred to as ferrous materials. (Learn more ...)
Membrane Interface Probe with Electron Capture Detectors (ECD)
A membrane interface probe (MIP) is a semi-quantitative, field-screening device that can detect VOCs in vadose and saturated soils. It is used in conjunction with a direct-push technology (DPT) platform, such as a CPT rig or a rig that uses a hydraulic or pneumatic hammer to drive the MIP to the depth of interest to collect samples of vaporized compounds. The probe captures the vapor sample, and a carrier gas transports the sample to the surface for analysis by a variety of field or laboratory analytical methods. The ECD is used to detect chlorinated VOCs such as tetrachloroethene (PCE) and trichloroethene (TCE). (Learn more ...)
Membrane Interface Probe with Flame Ionization Detector (FID)
An MIP is a semi-quantitative, field-screening device that can detect VOCs in vadose and saturated soils. It is used in conjunction with a DPT platform, such as a CPT rig or a rig that uses a hydraulic or pneumatic hammer to drive the MIP to the depth of interest to collect samples of vaporized compounds. The probe captures the vapor sample, and a carrier gas transports the sample to the surface for analysis by a variety of field or laboratory analytical methods. The FID is used to detect straight chained hydrocarbons such as methane and butane. (Learn more ...)
Membrane Interface Probe with Photoionization Detector (PID)
An MIP is a semi-quantitative, field-screening device that can detect VOCs in vadose and saturated soils. It is used in conjunction with a DPT platform, such as a CPT rig or a rig that uses a hydraulic or pneumatic hammer to drive the MIP to the depth of interest to collect samples of vaporized compounds. The probe captures the vapor sample, and a carrier gas transports the sample to the surface for analysis by a variety of field or laboratory analytical methods. The PID is used to detect aromatic hydrocarbons, such as BTEX compounds. (Learn more ...)
Near Infrared Reflectance/ Transmittance Spectroscopy
Near infrared reflectance/transmittance spectroscopy involves airborne remote sensing identification of subsurface VOC contamination. It uses reflectance signals resulting from bending and stretching vibrations in molecular bonds between carbon, nitrogen, hydrogen, and oxygen. Calibration is required to correlate the spectral response of each sample at individual wavelengths to known chemical concentrations from laboratory analysis. (Learn more ...)
Photoionization Detector (PID)
The portable hand-held PID is composed of an ultraviolet lamp that emits photons (a quantum unit of light energy) that are absorbed by the analyte in an ionization chamber. Ions produced during this process are collected by electrodes. The current generated provides a measure of the analyte concentration. PIDs are commonly used as detectors in portable gas chromatographs (GCs, which separate the specific analyte types). Because only a small fraction of the analyte molecules are actually ionized, this method is considered nondestructive, allowing it to be used in conjunction with another detector to confirm analysis results. Confirmation is easily accomplished by connecting the exhaust port of the PID to a FID or ECD. (Learn more ...)
Piezoelectric Sensors
Piezoelectric sensors screen for chlorinated hydrocarbons and other VOC gases. Sensors using piezoelectric materials develop an electrical response to changes in pressure. Typically, oscillating materials are used as sensitive gravimetric detectors. Selective coatings allow specific organic solvent vapors to be sorbed on the crystal. The increased mass of the crystal resulting from sorption changes the frequency of oscillation, which can be correlated with concentration. (Learn more ...)
Raman Spectroscopy/ Surface-Enhanced Raman Scattering (SERS)
Raman spectroscopy encompasses a variety of techniques that involve detection and analysis of the scattering of radiation. Raman spectroscopy is the measurement of the wavelength and intensity of inelastically scattered light from molecules. When electromagnetic radiation passes through matter, most of the radiation continues in its original direction but a small fraction is scattered in other directions. (Learn more ...)
Room-Temperature Phosphorimetry
Room-temperature phosphorimetry is based on detecting the phosphorescence emitted from organic compounds absorbed on solid substrates at ambient temperatures. (Conventional phosphorimetry requires cryogenic [low temperature] equipment.) Instrument design is similar to fluorescence techniques. (Learn more ...)
Scattering/Absorption LIDAR
Light detection and ranging (LIDAR) measurements of atmospheric trace gases have historically employed two basic techniques: elastic scattering differential absorption LIDAR (DIAL) and inelastic scattering Raman LIDAR. (Learn more ...)
Semiconductor Sensors
Semiconductor sensors screen for chlorinated hydrocarbons in water and gas samples. Semiconductor sensors are designed to respond electrically to the substance of interest. (Learn more ...)
Soil-Gas Analyzer Systems
Soil-gas sampling systems have been developed as part of multiple-use sampling tools. The Simulprobe soil sampler can be used in its "drive and sniff" mode, allowing soil gases to be continuously collected while the sampler is advanced into the subsurface. Based on the field screening of the soil gas sample, a collocated soil sample can be immediately collected. Similarly, the ConeSipper can be used to collect soil gas samples in the vadose zone, and then collect groundwater samples as the tool advances below the water table. Finally, most dual-tube sampling systems can be used for alternating soil and soil gas sampling. (Learn more ...)
Solid/Porous Fiber Optic
Fiber optics is a technique that transmits light through long, thin, flexible fibers of glass, plastic, or other transparent material. Parallel fibers bundled together can be used to transmit complete images. The most common fiber-optic sensors send an excitation signal from a light source that is transmitted down the cable to a sensor. The sensor fluoresces and provides a constant-intensity light source that is transmitted back up the cable and detected as the return signal. The intensity of the return signal is reduced if the target contaminant is present. (The intensity of the light that is recorded by the detector is inversely proportional to the concentration.) The configuration of a fiber-optic sensor system requires a simple light source, a detector, and simple optics to focus and guide light into and out of the fiber-optic conduit. The same fiber can be used to transmit the probe beam to the sensor, as well as to carry the modulated signal back to the detector. At the proximal end of the fiber is a small calculator-size box of optics and electronics that contains both the light source and the signal detection equipment. (Generally, the fiber optic cable is attached to a spectrophotometer or a fluorometer, which contains both a light source and a detector.) The electronics box is configured to a small central processing unit or a lap-top computer that collects and analyzes the sensor signals and provides useful information on the analyte concentration. At the distal and working end of the fiber is the sensor, normally encased in a protective metal shield to prevent damage. (Learn more ...)
Synchronous Luminescence/ Fluorescence
Synchronous luminescence/fluorescence involves semi-quantitative analysis of PAHs and field screening of BTEX. Synchronous luminescence/fluorescence involves the use of both emission and excitation monochromators to record the luminescence signal, which allows greater selectivity in the analysis of environmental samples. Instruments use a sweeping motion, similar to using a metal detector, to scan the site. During this operation, light of a narrow wavelength is projected from the detector head onto the surface being inspected, causing excitation fluorescence of the targeted materials. Low-level light energy released from the excited material's fluorescence is: (1) filtered to reject unwanted wavelengths of reflected and ambient light, (2) amplified, (3) converted to a video signal, and (4) relayed to the monitor. Light areas displayed on the monitor's darker background indicate the presence of contamination to the operator. (Learn more ...)
Thin-Layer Chromatography
Thin-layer chromatography consists of a stationary phase immobilized on a glass or plastic plate and a solvent. The sample, either liquid or dissolved in a volatile solvent (n-butanol and cellulose acetate), is deposited as a spot on the stationary phase. The constituents of a sample can be identified by simultaneously running standards with the unknown. One edge of the plate is then placed in a solvent reservoir and the solvent moves up the plate by capillary action. When the solvent front reaches the other edge of the stationary phase, the plate is removed from the solvent reservoir. The separated spots are visualized with ultraviolet light or by placing the plate in iodine vapor. The different components in the mixture move up the plate at different rates as a result of differences in their partitioning behavior between the mobile liquid phase and the stationary phase. (Learn more ...)
Titrimetry Kits
Titrimetry kits are used for analyzing samples contaminated with heavy metals. Titrimetry is a wet chemistry procedure by which a solution of known concentration is added to a water sample or soil-solute extract with an unknown concentration of the analyte of interest until the chemical reaction between the two solutions is complete (the equivalence point of titration). Titrimetry requires an abrupt change in some property of the solution at the equivalence point, which is typically produced by a change in color produced by an added dye, or by monitoring changes in pH with a meter. (Learn more ...)
Toxicity Tests
Toxicity tests use specific aquatic and terrestrial organisms or microorganisms to measure biological response to specific contaminants or mixtures of contaminants. The toxicity test consists of luminescent microorganisms that emit light as a normal consequence of respiration and a temperature controlled illuminometer that reads the bacterial light output. Chemicals or chemical mixtures that are toxic to the bacteria cause a reduction in light output proportional to the strength of the toxin. A computer is linked to the system to provide data processing and storage capabilities. (Learn more ...)
Ultraviolet Fluorescence
UV fluorescence has been used in a number of applications for field screening including: (1) semi-quantitative analysis of solvent extracted PAHs, (2) in conjunction with fiber optic sensors, and (3) as a surface contamination detector, in which a non-fluorescing substance sprayed on the ground surface reacts chemically with the contaminant of interest to form a substance that fluoresces with UV excitation. (Learn more ...)
Ultraviolet Visible Spectrophotometry
Ultraviolet Visible Spectrophotometry is used to detect transition metal ions, highly conjugated organic compounds, and biological macromolecules. It encompasses a number of techniques involving measurement of the absorption spectra of narrow band widths of radiation. Visible spectrometry covers the range of 380 to 780 nano-meters (nm) and uses tungsten lamps as the radiation source, glass or quartz prisms in the monochromators, and photo-multiplier cells as the detector. UV spectrometers cover the region from 200 to 400 nm and usually use a hydrogen lamp as a radiation source, a quartz prism in the monochromator, and a photo-multiplier tube as the detector. (Learn more ...)
Waterloo Advanced Profiling System
The Waterloo Advanced Profiling Systems (WaterlooAPS) is a direct-push groundwater sampling technology used to collect discrete interval samples in a continuous vertical profile. In addition to groundwater sample collection, the system provides measurements of other physiochemical data, including a continuous real-time read-out of an Index of Hydraulic Conductivity (Ik), hydraulic head, specific conductance (SC), dissolved oxygen (DO), pH, oxidation-reduction potential (ORP), and temperature. The stainless-steel profiling tip has 16 ports arranged in four rows with an open sampling interval approximately 2.5 inches in length. Port screens can be changed to reduce turbidity or optimize sampling productivity. To minimize sorption of contaminants to system materials, stainless steel tubing conveys groundwater from the profiling tip to the sample collection apparatus at the surface. A sacrificial profiling tip allows retraction grouting of completed profiling boreholes. Groundwater samples are collected using either a peristaltic or a downhole nitrogen gas-drive pump, depending on depth to the water table. Samples are collected directly into glass, zero-headspace, in-line sample containers that prevents sample contact with system materials and ambient air. The containers are located on the suction side of the peristaltic pump to prevent contact with pump head tubing. (Learn more ...)
Treatment technologies that are associated with this site type are listed below. Click on the name of the technology to view details.
G - Groundwater, leachate, and surface water
S - Soils, sediments, and sludges
| Technology | Fuels | Metals and Metalloids | Nonhalogenated SVOCs | Nonhalogenated VOCs |
|---|---|---|---|---|
| Air Sparging | G | G | ||
| Bioremediation | G/S | G/S | G/S | |
| Chemical Treatment | G/S | G/S | G/S | G/S |
| Electrokinetics | G/S | G/S | G/S | |
| Flushing | G/S | G/S | G/S | G/S |
| Incineration | S | S | S | |
| In-Well Air Stripping | G | |||
| Multi-Phase Extraction | G/S | G/S | G/S | |
| Nanoremediation | G/S | G/S | G/S | G/S |
| Permeable Reactive Barrier | G | G | G | G |
| Physical Separation | S | S | ||
| Phytoremediation | G/S | G/S | G/S | G/S |
| Pump and Treat | G | G | G | G |
| Soil Amendments | S | S | S | |
| Soil Vapor Extraction | S | S | ||
| Soil Washing | S | S | S | S |
| Solidification/Stabilization | S | S | S | S |
| Solvent Extraction | S | S | S | S |
| Thermal Desorption | S | S | S | |
| Thermal Treatment (in situ) | G/S | G/S | G/S | |
| Vitrification | S | S | S | S |
Air Sparging
Air sparging involves injection of air or oxygen into a contaminated aquifer. Injected air traverses horizontally and vertically in channels through the soil column, creating an underground stripper that removes volatile and semivolatile organic contaminants by volatilization. The injected air helps to flush the contaminants into the unsaturated zone. Soil Vapor Extraction (SVE) usually is implemented in conjunction with air sparging to remove the generated vapor-phase contamination from the vadose zone. Oxygen added to the contaminated groundwater and vadose zone soils also can enhance biodegradation of contaminants below and above the water table. (Learn more ...)
Bioremediation
Bioremediation involves use of microorganisms to degrade organic contaminants in soil, sludge, solids, and groundwater either in situ or ex situ. It can also be used to make metals or metalloids less toxic or mobile. When organic contaminants are being treated, the microorganisms break down contaminants by using them as a food source or by cometabolizing them with a food source. Aerobic processes require an oxygen source, and the end products typically are carbon dioxide and water. Anaerobic processes are conducted in the absence of oxygen, and the end products can include methane, hydrogen gas, sulfide, elemental sulfur, and nitrogen gas. Bioremediation techniques stimulate and create a favorable environment for microorganisms to grow and use contaminants as a food and energy source or to cometabolize them. Generally, this process involves providing some combination of oxygen (for aerobic processes only), food, nutrients, and moisture and controlling the temperature and pH. Microorganisms that have been adapted for degradation of specific contaminants are sometimes added to enhance the process. The process for treatment of metals and metalloids involves biological activity that promotes formation of less toxic or mobile species by creating ambient conditions that will cause these species to form or by acting directly on the contaminant. The treatment may result in oxidation, reduction, precipitation, coprecipitation, or another transformation of the contaminant. (Learn more ...)
Chemical Treatment
Chemical treatment, also known as chemical reduction/oxidation (redox), typically involves redox reactions that chemically convert hazardous contaminants into compounds that are nonhazardous, less toxic, more stable, less mobile, or inert. Redox reactions involve the transfer of electrons from one compound to another. Specifically, one reactant is oxidized (loses electrons) and one reactant is reduced (gains electrons). The oxidizing agents used for treatment of hazardous contaminants in soil include ozone, hydrogen peroxide, hypochlorites, potassium permanganate, Fentons reagent (hydrogen peroxide and iron), chlorine, and chlorine dioxide. This method may be applied in situ or ex situ to soils, sludges, sediments, and other solids, and may also be applied to groundwater in situ or ex situ chemical treatment using pump and treat technology. Pump and treat chemical treatment may also include use of ultraviolet (UV) light in a process known as UV oxidation. (Learn more ...)
Electrokinetics
Electrokinetics is based on the theory that a low-density current will mobilize contaminants in the form of charged species. A current passed between electrodes is intended to cause aqueous media, ions, and particulates to move through soil, waste, and water. Contaminants arriving at the electrodes can be removed by means of electroplating or electrodeposition, precipitation or coprecipitation, adsorption, complexing with ion exchange resins, or pumping water (or other fluid) near the electrodes. (Learn more ...)
Flushing
For flushing, a solution of water, surfactants, or cosolvents is applied to soil or injected into the subsurface to treat contaminated soil or groundwater. When soil is treated, the injection is often designed to raise the water table into the contaminated soil zone. Injected water and treatment agents are recovered together with flushed contaminants. (Learn more ...)
Incineration
Both on-site and off-site incineration involves use of high temperatures (870 to 1,200°C or 1,600 to 2,200°F) to volatilize and combust (in the presence of oxygen) organic compounds in hazardous wastes. Auxiliary fuels are often used to initiate and sustain combustion. The destruction and removal efficiency of properly operated incinerators exceeds the 99.99 percent requirement for hazardous waste and can meet the 99.9999 percent requirement for PCBs and dioxins. Off-gases and combustion residuals generally require treatment. On-site incineration is typically a transportable unit. Waste is transported to a central facility for off-site incineration. (Learn more ...)
In-Well Air Stripping
For in-well air stripping, air is injected into a double-screened well, causing the VOCs in the contaminated groundwater to be transferred from the dissolved phase to the vapor phase in air bubbles. As the air bubbles rise to the surface of the water, the vapors are drawn off and treated by an SVE system. (Learn more ...)
Multi-Phase Extraction
Multi-phase extraction involves use of a vacuum system to remove various combinations of contaminated groundwater, separate-phase petroleum product, and vapors from the subsurface. The system typically lowers the water table around a well, exposing more of the formation. Contaminants in the newly exposed vadose zone are then accessible for vapor extraction. Once above ground, the extracted vapors or liquid-phase organics and groundwater are separated and treated. (Learn more ...)
Nanoremediation
Nanoremediation is a relatively new technology for environmental remediation. Nanotechnology is the understanding and control of matter at dimensions between approximately 1 and 100 nanometers, where unique phenomena enable novel applications (National Nanotechnology Initiative [NNI] 2008). Nanoparticles can be highly reactive because of their large surface area to volume ratio and the presence of a greater number of reactive sites. These features allows for increased contact with contaminants, thereby resulting in rapid reduction of contaminant concentrations. (Learn more ...)
Permeable Reactive Barrier
Permeable reactive barriers (PRB), also known as passive treatment walls, are installed across the flow path of a contaminated groundwater plume, allowing the water portion of the plume to flow through the wall. These barriers allow passage of water while prohibiting movement of contaminants by means of treatment agents within the wall such as zero-valent metals (usually zero-valent iron), chelators, sorbents, compost, and microbes. The contaminants are either degraded or retained in a concentrated form by the barrier material, which may need to be replaced periodically. (Learn more ...)
Physical Separation
Physical separation processes use physical properties to separate contaminated and uncontaminated media or to separate different types of media. For example, different-sized sieves and screens can be used to separate contaminated soil from relatively uncontaminated debris. Another application of physical separation is dewatering sediments or sludge. (Learn more ...)
Phytoremediation
Phytoremediation is a process in which plants are used to remove, transfer, stabilize, or destroy contaminants in soil, sediment, or groundwater. The mechanisms of phytoremediation include enhanced rhizosphere biodegradation (which takes place in soil or groundwater immediately around plant roots), phytoextraction (also known as phytoaccumulation, the uptake of contaminants by plant roots and the translocation and accumulation of contaminants into plant shoots and leaves), phytodegradation (metabolism of contaminants within plant tissues), and phytostabilization (production of chemical compounds by plants to immobilize contaminants at the interface of roots and soil). Phytoremediation applies to all biological, chemical, and physical processes that are influenced by plants (including the rhizosphere) and that aid in the cleanup of contaminated substances. Phytoremediation may be applied in situ or ex situ to soils, sludges, sediments, other solids, or groundwater. (Learn more ...)
Pump and Treat
Pump and treat involves extraction of groundwater from an aquifer and treatment of the water above the ground. The extraction step is usually conducted by pumping groundwater from a well or trench. The treatment step can involve a variety of technologies such as adsorption, air stripping, bioremediation, chemical treatment, filtration, ion exchange, metal precipitation, and membrane filtration. (Learn more ...)
Soil Amendments
Many soils, particularly those found in urban, industrial, mining, and other disturbed areas, suffer from a range of physical, chemical, and biological limitations. They include soil toxicity, too high or too low pH, lack of sufficient organic matter, reduced water-holding capacity, reduced microbial communities, and compaction. Appropriate soil amendments may be inorganic (such as liming materials), organic (for example, composts) or mixtures (such as lime-stabilized biosolids). When specified and applied properly, these beneficial soil amendments limit many of the exposure pathways and reduce soil phytotoxicity. Soil amendments also can restore appropriate soil conditions for plant growth by balancing pH, adding organic matter, restoring soil microbial activity, increasing moisture retention, and reducing compaction. Soil amendments can reduce the bioavailability of a wide range of contaminants while simultaneously enhancing success of revegetation and, thereby, protecting against off-site movement of contaminants by wind and water. As such, they can be used in situations ranging from time-critical contaminant removal actions to long-term ecological revitalization projects. Using these residual materials (industrial byproducts) offers the potential for significant cost savings compared with traditional alternatives. In addition, land revitalization using soil amendments has significant ecological benefits, including benefits for the hydrosphere and atmosphere. (Learn more ...)
Soil Vapor Extraction
Soil vapor extraction (SVE) is used to remediate unsaturated (vadose) zone soil. A vacuum is applied to the soil in order to induce a controlled flow of air and remove volatile and some semivolatile organic contaminants from the soil. SVE usually is performed in situ; however, in some cases, it can be used as an ex situ technology. (Learn more ...)
Soil Washing
For Soil washing, contaminants sorbed onto fine soil particles are separated from bulk soil in a water-based system based on particle size. The wash water may be augmented with a basic leaching agent, surfactant, or chelating agent or by adjusting pH to help remove contaminants. Soils and wash water are mixed ex situ in a tank or other treatment unit. The wash water and various soil fractions are usually separated by means of gravity settling. (Learn more ...)
Solidification/Stabilization
Solidification/stabilization (S/S) reduces the mobility of hazardous substances and contaminants in the environment through both physical and chemical means. The S/S process physically binds or encloses contaminants within a stabilized mass. S/S can be performed both ex situ and in situ. Ex situ S/S requires excavation of the material to be treated, and the treated material must be disposed of. In situ S/S involves use of auger or caisson systems and injector head systems to add binders to contaminated soil or waste without excavation, and the treated material is left in place. (Learn more ...)
Solvent Extraction
Solvent extraction involves use of an organic solvent as an extractant to separate contaminants from soil. The organic solvent is mixed with contaminated soil in an extraction unit. The extracted solution is then passed through a separator, where the contaminants and extractant are separated from the soil. (Learn more ...)
Thermal Desorption
For thermal desorption, wastes are heated so that organic contaminants and water volatilize. Typically, a carrier gas or vacuum system transports the volatilized organic compounds and water to a gas treatment system, usually a thermal oxidation or recovery system. Based on the operating temperature of the desorber, thermal desorption processes can be categorized in two groups: high-temperature thermal desorption (320 to 560°C or 600 to 1,000°F) and low-temperature thermal desorption (90 to 320°C or 200 to 600°F). Thermal desorption is an ex situ treatment process. (Learn more ...)
Thermal Treatment (in situ)
In situ thermal treatment is a treatment process that uses heat to facilitate contaminant extraction through volatilization and other mechanisms or to destroy contaminants in situ. Volatilized contaminants are typically removed from the vadose zone using SVE. Specific types of in situ thermal treatment include conductive heating, electrical resistive heating (ERH), radio frequency heating (RFH), hot air injection, hot water injection, and steam-enhanced extraction. In situ thermal treatment is usually applied to a contaminated source area but may also be applied to a groundwater plume. (Learn more ...)
Vitrification
Vitrification involves use of an electric current to melt contaminated soil at elevated temperatures (1,600 to 2,000°C or 2,900 to 3,650°F). When it cools, the vitrification product is a chemically stable, leach-resistant glass and crystalline material similar to obsidian or basalt rock. The high-temperature component of the process destroys or removes organic materials. Radionuclides and heavy metals are retained within the vitrified product. Vitrification may be conducted in situ or ex situ. (Learn more ...)
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