Triangle NoTES - August 2011

There are a lot of new things happening, which is the reason for this newsletter so closely following the last. I have also been requested to include a summary overview of the newsletter in the beginning for those who do not wish to get into the more technical aspects. This will be my first attempt to provide such a summary.

There have been some questions voiced over how to economically identify possible fire conditions in landfills. One state has proposed a determination of CO, with anything reported below a 100 ppm threshold being considered a non-concern. We have developed a possible method for reporting CO in this range as part of the typical Method 3-C analysis instead of the separate Method 10-B analysis or as part of the Method 25-C, where the reporting limits are higher. This is currently still an experimental method which will be reported separately until the studies to document the usage are completed.

We have the MDL study for the Modified Method 3-C completed, as well as an initial calibration that will cover up to the low percent levels of CO. Since LFG has to be diluted for shipping and for analysis, the specific range for any sample will vary. Given a sufficient sample volume of ~1.75 L with the normal dilutions for analysis, the lower reporting limit for CO would be ~75 ppm using this method. Of course, if the sample volume taken is larger or there is no requirement for a Method 25-C analysis from the same sample, this may be adjusted lower. There will be a second processing of the data and a separate section of the report for CO in the initial stages. This allows no confusion between the strict method and the modified method report for CO. There will be some questions the accreditation auditors and the regulatory advisors will have to answer before we make any changes to include CO in the standard report. Thus, there will be a slight charge for the additional labor aspects at least for a time. In any case, it should be more economical than the current means to report at that lower level.

We should also be able to add the reporting of CO to the GHG report in the future. As it stands, we would have to do a similar secondary report since the two procedures are so closely linked in our software. The major difference is the calibration range for the GHG analysis will be < 2000 ppm for most samples, but with a theoretical low range of ~10 ppm if the sample volume is sufficient and there is minimal dilution used. The same nominal cost for the modified Method 3-C would apply to this addition until we have more information on how the addition of CO would impact the acceptance of the Method 3-C report since it is a modification and may cause the entire report to be labeled as such. That might cause problems with the acceptance of the other un-modified analytes.

The MDL studies indicate a much lower range for both methods should be possible, but we do not feel comfortable with even the common multipliers generally this instance. For that reason, the lowest calibration level for the Method 3-C will probably determine the lowest concentration we report. The GHG method will most likely have too much interference from air to allow it to be used as effectively as the MDL would suggest. The Method 10-B will probably still be the better choice once all of the data is available.

Wayne Stollings

Triangle Environmental Services, Inc.