Petroleum cleanup levels

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. 

There are several reasons why the data for total petroleum hydrocarbons do not provide ideal information for investigating sites and establishing target cleanup criteria. For example, use of the term total petroleum hydrocarbons suggests that the analytical method measures the combined concentration of all petroleum-derived hydrocarbons, thereby giving an accurate indication of site contamination. But this is not always the case. Furthermore, target cleanup levels based on total petroleum hydrocarbons concentrations implicitly assume (1) that the data are an accurate measurement of petroleum-derived hydrocarbon concentration, and (2) the data also indicate the level of risk associated with the contamination. These assumptions are not correct due to many factors, including the nonspecificity of some of the methods used and the complex nature of petroleum hydrocarbons and their interaction with the environment over time. 

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 ... 

Table 32.3 summarizes the chemical analysis results for nine heaps at the end of 177 days. Two heaps were excluded from the assessment due to the presence of a mixed organic/inorganic pollution. Of special interest was TPH in C25-C35, which could not be remedied by microbiological methods. In all heaps, the different types of petroleum product responded to ECGO. TPH after 177 days of treatment was substantially below regulatory cleanup levels. As to PAH, the concentrations prior to the test were already below the cleanup levels and are reproduced only for purposes of completeness. 

Most investigations involving petrolenm hydrocarbons are regulated by various agencies that may require methodologies, action levels, and cleanup criteria that are different. Indeed, the complex chemical composition of petroleum and petroleum products can make it extremely difficult to select the most appropriate analytical test methods for evaluating environmental samples and to interpret and use the data accurately. 

There are two noncolumn cleanup methods, one of which uses acid partition (EPA SW-846 3650) to separate the base/neutral and acid components by adjusting pH. This method is often used before alumina column cleanup to remove acid components. The other method (EPA SW-846 3660) is used for sulfur removal and uses copper, mercury, and tetrabutylammonium sulfite as desulfurization compounds. Sulfur is a common interfering compound for petroleum hydrocarbon analysis, particularly for sediments. Sulfur-containing compounds are very common in crude oil and heavy fuel oil. Elemental sulfur is often present in anaerobically biodegraded fuels. Thus, abnormally high levels of sulfur may be... 

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... 

A common problem at public utilities is soil that becomes contaminated with PCBs near and around transformers. There still are a number of such sites with this problem in the United States. Table 9 gives data from a soil cleanup project from a site in New York State. The soil contained approximately 1200 ppm of PCB (Aroclor 1260) prior to treatment with SET . After treatment, the PCB level was reduced to 1.4 ppm (Table 9). Aroclor 1260 is particularly hard to bioremediate, so this result is significant. Small quantities of PAHs (pyrene and phenanthrene) were also remediated. The total petroleum hydrocarbons increased, which is what should be expected because the initial... 

In recent several years, many EPA and ASTM methods have been modified (such as the modified EPA method 8015, 8260 and 8270 and the modified ASTM methods 3328-90, 5037-90 and 5739-95) to improve specificity and sensitivity for measuring spilled oil and petroleum products in soils and waters by environmental chemists. For example, EPA Method 8270 has been modified to increase analytical sensitivity and to expand the analyte list to include petroleum specific compounds such as the alkylated PAHs, sulfur, and nitrogen containing PAHs, and biomarker triterpane and sterane compounds. The principal modification to EPA Method 8270 is the use of the high resolution GC-MS selected ion mode (SIM) analysis that olfers increased sensitivity relative to the full scan mode. Many environmental laboratories have used the modified EPA Method 8270, combined with column cleanup and rigorous QA measures, to identify and quantify low levels of hydrocarbons. 

Universal across-the-board cleanup criteria are not commonly used as end points for soil and groundwater cleanup, because of the wide range of risks found at these sites. However, two classes of contaminants have been subject to universal action levels for cleanup petroleum and polychlorinated biphenyls (PCBs). Most petroleum hydrocarbon action levels are regulated by state and local agencies the parameters used and their corresponding action levels vary widely from state to state. The specific petroleum parameters that are regulated include total petroleum hydrocarbon— gasoline fraction (TPH-G) total petroleum hydrocarbon—diesel component (TPH-D) ... 

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