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Data Reporting Questions

Test Methods:  Frequently Asked Questions

Reporting Forms, Qualifier Flags, and Reporting Units

Question: Where can I find the SW-846 data reporting forms?

Answer: The short answer is that there are no longer any data reporting forms in the SW-846 manual.

Early versions of the manual included copies of data reporting forms that were used as part of the contractual statements of work for the Superfund Contract Laboratory Program (CLP) in the early 1980s. However, those forms did not include a majority of the analytes of interest (e.g, regulated) under RCRA and they also assumed that the quality control checks used in the CLP applied to methods used for other purposes and other EPA programs. In addition, beginning in 1986, the forms used in the CLP changed significantly from those that were once shown in SW-846.

OSW (renamed Office of Resource Conservation and Recovery, ORCR, on January 18, 2009) considers data reporting to be a project-specific issue and as a result, there is not a one-size-fits-all approach to data reporting. Therefore, in 1994, when Update II to the 3rd Edition was promulgated, the outdated CLP forms were removed from the manual and not replaced.

Data reporting should be addressed in the QA plan or the sampling and analysis plan for a given project, or in the contract with the laboratory. Those documents should address what data are to be reported, the level of detail that is required, and the format (paper, electronic, or both) in which the data should be presented. There are several commercially-available software packages available to laboratories that can be used to generate data reporting forms and formats and that will accommodate analytes in SW-846 methods.

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Question: Where can I get a list of data qualifier flags?

Answer: As noted above, ORCR considers data reporting to be a project-specific issue. Therefore, data reporting forms and qualifiers are not described in the SW-846 manual. If you have a data report from a laboratory that does not include the definitions of the qualifiers that they used, then you should contact that laboratory and request that information.

Lists of qualifiers used in other EPA programs (e.g., CLP, NPDES) may be available from those programs, but they are not part of SW-846.

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Question: How do I convert results in parts per million to milligrams per kilogram (or vice versa)?

Answer: The two units are equivalent. A milligram (mg) is one-thousandth of a gram (g), which in turn is one-thousandth of a kilogram (kg). Therefore, a milligram is one one-millionth of a kilogram and 1 milligram per kilogram (mg/kg) equals 1 part per million parts, or 1 ppm.

A similar relationship exists for aqueous samples because 1 liter of water weighs approximately 1 kilogram, if you ignore the small density differences between pure water and the majority of environmental samples. Thus, 1 mg/L is equivalent to 1 ppm.

Similarly, 1 microgram per liter (ug/L) or 1 microgram per kilogram (ug/kg) is equivalent to 1 part per billion parts, or 1 ppb.

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Question: I sent a solid sample to the laboratory for TCLP and they sent back results in units of milligrams per liter (mg/L). How can a solid sample have a concentration in terms of its volume in liters?

Answer: The TCLP is a leaching procedure that is used to evaluate a sample to see if it exhibits the RCRA characteristic of toxicity, as defined in 40 CFR 261.24. As part of the TCLP process, the sample is leached with a specific acidic solution and the resulting liquid leachate is subsequently analyzed. Since the leachate is a liquid, the results from its analysis are reported in units of milligrams per liter, even though the original sample was a solid.

Because the regulatory limits used in the toxicity characteristic apply to the leachate, the units are also expressed in units of milligrams per liter (mg/L). As a result, you do not need to convert the units for these results and you can simply compare the results to the numerical limits for the toxicity characteristic shown in 40 CFR 261.24.

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Blank Subtraction

Question: Does the Office of Resource Conservation and Recovery support the use of blank subtraction when reporting sample results? We had to dilute some Method 8260B volatile samples by a factor of 10,000:1 for analysis and now we need to explain the low level contamination in the method blank.

Answer: ORCR does NOT support blank subtraction when reporting sample results. Data can easily be misinterpreted if improperly corrected for the blank contribution or not clearly explained in the data report. General guidelines on the interpretation of method blank results were added in Section 8.2.6 of Method 8000B, including guidance indicating that data should not be corrected for the blank contribution. Providing a table of sample results, blank results, and blank results multiplied by the dilution factor may help clarify the data reports.

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Levels of Data Reporting

Question: Where can I find a definition of "Tier III" data reporting?

Answer: ORCR has not defined tiers or levels of data reporting because data reporting is project-specific issue. At one time, the Superfund Program defined tiered levels of data reporting or data quality. However, those levels were never part of SW-846.

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