U.S. EPA Contaminated Site Cleanup Information (CLU-IN)


U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

Dense Nonaqueous Phase Liquids (DNAPLs)

Detection and Site Characterization

Multi-Component Waste

This section highlights technologies that are specific to creosotes, coal tars, and heavy oils. As is shown in the Chemistry and Behavior section of the DNAPL pages, each of these substances contains individual compounds with a wide range of solubilities, and their dissolved-phase plumes will reflect this range. The physics of large volume releases combined with lower viscosity compounds should dictate more movement on the part of creosote. Many broad-based analytical methods and groundwater profiling tools can be useful in helping to find and characterize these substances.

Multi-Component Waste
Creosotes
Coal Tars
Heavy Oils

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Characterization | Standard Laboratory Methods | Field Screening Methods


Characterization

For depths under 100 feet, subsurface characterization of DNAPLs is generally accomplished by direct push (DP) equipment. Dual-tube rigs can provide continuous soil cores that can be examined immediately for evidence of NAPL. When using these tools, care should be taken not to penetrate confining layers and cause cross-contamination. They also provide exact lithological and contaminant location information. DP rigs can be equipped with tools that provide relative contaminant data. For example, induced fluorescence probes (discussed below in Field Screening Methods) are useful for profiling relative concentrations of these substances through a soil column, as are membrane interface probes and GeoVis.

For coal tars associated with manufactured gas plants (MGPs), geophysical techniques should be considered for the initial characterization phase to aid in locating the numerous subsurface structures often found at these sites.

Adobe PDF LogoHeavy Oil Detection (Prototypes) Final Report
Hansen, K.A., M. Fitzpatrick, P.R. Herring, and M. VanHaverbeke.
Report No. CG-D-08-09, 74 pp, July 2009

This report describes an assessment of detection techniques using sonar, laser fluorometry, real-time mass spectrometry, and in situ fluorometry to locate oil sitting on the sea floor. . This report contains the results of the tests and provides recommendations in Appendix E for federal on-scene coordinators when responding to spills of heavy oil.

Adobe PDF LogoTools and Techniques for Expediting Site Characterization
Chapter 4 in A Resource for MGP Site Characterization and Remediation: Expedited Site Characterization and Source Remediation at Former Manufactured Gas Plant Sites, EPA 542-R-99-005, 72 pp, 1999

This chapter provides a discussion of different technologies that can be used to characterize coal tars and associated chemicals found at MGP sites.

Standard Laboratory Methods

The dissolved fraction of these mixtures will often contain monoaromatics (benzene, toluene, ethyl benzene, and xylenes) and lighter polycyclic aromatic compounds, such as anthracene, naphthalene, and phenanthrene. Creosotes may have phenols associated with them. An actual sample of the substance will contain hundreds of individual chemical species, including the carcinogenic polycyclic aromatic compounds, such as benzo(a)pyrene.

For a general discussion of laboratory methods used for creosotes and coal tars, see the Analytical Methods sectionAdobe PDF Logo of the creosote toxicological profile developed by the Agency for Toxic Substances and Disease Registry.

EPA Method 8260B (aromatics, among other chemicals), 8270C (semivolatiles, including phenols and polycyclic aromatics), and OLM04.2: Organics Analysis Multi-Media, Multi-Concentration are described on the Detection and Site Characterization introductory page because they are applicable to many DNAPL chemicals. Note that gas chromatography (GC) and GC/mass spectroscopy (MS) equipment are field deployable, and methods using these instruments are equally valid in the field.

Adobe PDF LogoMethod 8021B: Aromatic and Halogenated Volatiles by Gas Chromatography Using Photoionization and/or Electrolytic Conductivity Detectors (ECD)

Method 8021 is used to determine volatile organic compounds in a variety of solid waste matrices. This method is applicable to nearly all types of samples, regardless of water content, including groundwater, aqueous sludges, caustic liquors, acid liquors, waste solvents, oily wastes, mousses, tars, fibrous wastes, polymeric emulsions, filter cakes, spent carbons, spent catalysts, soils, and sediments. If the GC used does not employ two columns with different retention characteristics, the chemical identification will be tentative unless the site contains only the chemical of interest. The photoionization detector (PID) is preferred when aromatic chemicals are of interest.

Adobe PDF LogoMethod 8041: Phenols by Gas Chromatography

Method 8041 describes open-tubular, capillary column GC procedures for the analysis of phenols, using both single-column and dual-column/dual-detector approaches. If the GC does not employ two columns with different retention characteristics, the chemical identification will be tentative unless the site contains only the chemical of interest.

Adobe PDF LogoMethod 8100: Polynuclear Aromatic Hydrocarbons

Method 8100 is used to determine the concentration of certain polycyclic aromatic hydrocarbons (PAHs). The packed-column GC method described here cannot adequately resolve the following four pairs of compounds: anthracene and phenanthrene; chrysene and benzo(a)anthracene; benzo(b)fluoranthene and benzo(k)fluoranthene; and dibenzo(a,h)anthracene and indeno(1,2,3-cd)pyrene. The use of a capillary column instead of the packed column, also described in this method, may adequately resolve these PAHs; however, unless the purpose of the analysis can be served by reporting a quantitative sum for an unresolved PAH pair, either liquid chromatography (Method 8310) or GC/MS (Method 8270) should be used for these compounds.

Adobe PDF LogoMethod 8310: Polynuclear Aromatic Hydrocarbons

Method 8310 is used to determine the concentration of certain PAHs in groundwater and wastes. Use of Method 8310 presupposes a high expectation of finding the specific compounds of interest. If the purpose is to screen samples for PAHs, independent protocols for the verification of identity must be developed.

Field Screening Methods

Geophysics

Adobe PDF LogoElectromagnetic Induction and Measurements for GPR Creosote Contaminant Investigation
E.D. Guy, J.J. Daniels, J. Holt, S.J. Radzevicius, and M.A. Vendl.
Journal of Environmental and Engineering Geophysics, Vol 5 No 2, p 11-19, 2000

Geophysical surveys were conducted to assist in the characterization of a former industrial site prior to its remediation. After many years of wood treating operations at the site, the clay-rich surficial soils contained high concentrations of creosote. Data from multifrequency electromagnetic induction and ground penetrating radar parallel dipole (co-pole) and orthogonal dipole (crosspole) surveys revealed the approximate extent of contamination at the site and the locations of several contaminant-filled structures. The information thus obtained provided the basis for a comprehensive and cost-effective site remediation plan. The geophysical data interpretations were confirmed through exploratory trenching and soil sampling.

Adobe PDF LogoTwo-Dimensional Resistivity Investigation of the North Cavalcade Street Site, Houston, Texas, August 2003
W.H. Kress and A.P. Teeple.
U.S. Geological Survey, Scientific Investigations Report 2005-5205, 34 pp, 2003

During August 2003, the U.S. Geological Survey and U.S. EPA conducted a two-dimensional (2D) resistivity investigation at the North Cavalcade Street site to provide additional characterization of the DNAPLs and the lithologies that can influence contaminant migration. The 2D resistivity investigation used a capacitively coupled (CC) resistivity method as a reconnaissance tool to locate geophysical anomalies that could be associated with possible areas of creosote contamination. The inversion results of the CC resistivity survey identified resistive anomalies in the subsurface near the eastern and western contaminated source areas. A direct-current (DC) resistivity survey conducted near the CC resistivity survey confirmed the occurrence of subsurface resistive anomalies. The inversion results of the DC resistivity survey were used to define the subsurface distribution of resistivity at each line.

More Information Within DNAPLS Section of Contaminant Focus on This Topic
Induced Fluorescence

Mono and polycyclic aromatic hydrocarbons will fluoresce when exposed to ultraviolet light. The intensity of the fluorescence of the individual compound depends upon the frequency of the excitation light. The individual compounds also have characteristic excitation frequencies. Downhole instrumentation has been developed that takes advantage of these two properties. These instruments can detect the presence of various types of aromatic mixtures as well as estimate their relative concentrations. The systems typically use either a laser or a mercury vapor lamp for a light source. Calcite and several other minerals also fluoresce, so background levels should always be determined to ensure proper readings.

Immunoassay

Enzyme immunoassays are biochemical procedures that utilize the binding of specific chemicals in a sample (with an enzyme-labeled version of the chemical) to antibodies provided with a test kit. Immunoassay test kits have not been designed to detect creosotes, coal tars, or heavy oils directly; however, kits are available that can be used to determine the level of PAH concentrations in a soil sample. CLU-IN hosts a page that provides a discussion of how immunoassays work.

Adobe PDF LogoMethod 4035: Soil Screening for Polynuclear Aromatic Hydrocarbons by Immunoassay

Method 4035 is a procedure for screening soils to determine when total PAHs are present at concentrations above 1 mg/kg. Method 4035 provides an estimate for the concentration of PAHs by comparison with a PAH standard.



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