Contaminated soil, cleanup methods

Accordingly, the total petroleum hydrocarbons at a gasoline spill site will be comprised of mostly Cs to Cu compounds, while total petroleum hydrocarbons at an older site where the fuel has weathered will likely measure mostly Cg to Cn compounds. Because of this inherent variability in the method and the analyte, it is currently not possible to directly relate potential enviromnental or health risks with concentrations of total petroleum hydrocarbons. The relative mobility or toxicity of contaminants represented by total petroleum hydrocarbons analyses at one site may be completely different from that of another site (e.g., Ce to Cn compared to Cio to C25). There is no easy way to determine if total petroleum hydrocarbons from the former site will represent the same level of risk as an equal measure of the total petroleum hydrocarbons from the latter. For these reasons it is clear that the total petroleum hydrocarbons value offers limited benefits as an indicator measure for cleanup criteria. Its current widespread use as a soil cleanup criterion is a function of a lack of understanding of its proper application and... 

Until very recently, explosives-contaminated soils have been remediated by incineration, a process whose high cost has stimulated the search for a more economical cleanup method (Roberts et al., 1993). Microbially mediated degradation of explosives is a promising technology. Many researchers have studied microbial consortia and various pure cultures for their ability to degrade TNT and other nitroaromatic compounds (for a review see Crawford, 1995), bringing about the development of bioremediation processes that can remove TNT and other explosives from contaminated soil and water (Funk etal., 1995 Williams a/., 1992). 

Petroleum hydrocarbons are a mixture of many substances. The results of petroleum analysis depend as much on the analytical method as the petroleum. As long as everyone works to a common definition there is no problem. The Total Petroleum Hydrocarbon Criteria Working Group (TPHCWG) convened in 1993 to develop scientifically defensible information for establishing soil cleanup levels that are protective of human health at petroleum contaminated sites. The TPHCWG compiled their data and analytical efforts into five volumes that can be accessed at http //www.aehs.com/publications/catalog/ contents/tph.htm ... 

Soil contaminated with levels of TCDD up to 9 ppm are subject to immediate response. About 2,000 m of such soil will be excavated and placed into an interim storage area upon approval by the Hamburg authorities. These contaminated soils will be stored until a destruction method becomes available. Such a method will be proposed upon conclusion of the drilling test program. Soil decontamination methods must also take account of the building and equipment cleanup procedures. 

If the soil is polluted, another cleanup method may be required to remediate contaminated ground. Thus, the coupled electrokinetic permeable reactive barrier system (EK-PRB) system should be effective to clean up polluted groundwater by the PRB system as well as to remediate contaminated ground by the EK system. The following section describes the investigations on a feasible field application of the EK remediation coupled with the PRB system to remediate contaminated ground of low-permeability soils. 

Solid-phase extraction (SPE) using small, disposable cartridges, columns, or disks is employed for isolation and cleanup of pesticides from water and other samples prior to TLC analysis, especially using reversed-phase (RP) octa-decyl (C-18) bonded silica gel phases. Microwave-assisted extraction (MAE) is a time- and solvent-saving method for removing residues from samples such as soils. Supercritical fluid extraction (SEE) has been used for sample preparation in the screening of pesticide-contaminated soil by conventional TLC and automated multiple development (AMD). Ultrasonic solvent extraction (USE) and videodensitometry have been combined for quantification of pesticides in sod. Matrix solid-phase dispersion (MSPD) with TLC and GC has been used to determine diazinon and ethion in nuts. 

Regulations for contaminated-site cleanup. Contains standards and methods for establishing cleanup levels groundwater, surface water, soil, and air emissions. 

Traditional environmental cleanup methods include approaches such as excavation and incineration of contaminated soil or pumping and aboveground treatment of groundwater. These techniques are both expensive and politically unpopular. Affordable, innovative technologies are needed by the environmental restoration industry. Bioremediation is such a technology. 

Morgan P, RJ Watkinson (1989b) Microbiological methods for the cleanup of soil and ground water contaminated with halogenated organic compounds. FEMS Microbiol Revs 63 277-300. 

With the recent Increase In activity at hazardous waste sites where cleanup and remedial action are underway, there has emerged a need for rapid analytical methods for assessing contamination in water, sediment, and soil. Of special Interest, because of widespread use and disposal. Is the group of materials known as PCB s (polychlorinated biphenyls). 

A number of techniques have been developed to directly volatilize soil components and contaminants and introduce them into the carrier gas of a gas chromatograph. Such procedures avoid the time and cost of extraction, cleanup, and concentration and also avoid the introduction of contaminants during the extraction process. However, these methods are not universally applicable and caution must be used when applying new or untested analyses or analytical procedures [2-5],... 

The analysis for the total petroleum hydrocarbons (TPHs) in a sample as a means of evaluating petroleum-contaminated sites is also an analytical method in common use. The data are used to establish target cleanup levels for soil or water by regulatory agencies in the United States and in many other countries. 

A coastal beach in California is polluted with heavy metals. Since it is a protected wildlife habitat, a minimally intrusive electrochemical method is selected for cleanup. Assume that a constant current density of 125 pA cm-2 in a 40 x 6-foot cross section is used in the contaminant pit, which is 40 x 20 x 6 feet deep, (a) What is the total current and voltage required if the pore fluid conductivity is 21.9 mS cm-1 (approx, equivalent to 0.2 M KC1) (b) If the soil is saturated and approx. 50% pore fluid and 50% solids by volume, how long would it take to pass a charge equivalent to the ionic content of the pore fluid (c) How much acid should be added to depolarize the cathode in this time in order to ensure reaction (A) below, instead of water electrolysis, reaction (B) ... 

Supercritical fluid extraction with carbon dioxide has long been proposed as a method for the cleanup of soils, sediments and sludges that are contaminated Avith toxic substances. An attractive feature of this process is that very little solvent residue remains in the processed... 

In some applications, the waste material may directly contain dioxins and furans, or it may contain halogens that could lead to the formation of dioxins and furans. Many of the U.S. Superfund cleanup sites contain soil that has been contaminated with halogenated compounds. One common method to clean the soil is to process it through an incinerator which reduces the contaminants to trace levels (see Chapter 8). 

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