GCI TECH NOTES ©
by David L. Constans and David Gossman
Last month's GCI Tech Notes listed the various standards that must be met under EPA's proposed MACT Rule for Hazardous Waste Combustors. That GCI Tech Notes also included the proposed MACT standards for the non-hazardous waste burning cement kilns.
Now that the final standard is looming, do you have enough data on your combustor or kiln to determine compliance? Hopefully you do, but you probably don't. This GCI Tech Notes will hopefully provide you with some timely advise in making this determination.
How Good is the Data You Already Have?
One of the recurrent problems GCI encounters is questionable data quality, especially for the dioxin sampling and analytical method (USEPA Method 23) and the trace metals sampling and analytical method (USEPA Method 29). The dioxin emissions sampling and analysis method is especially prone to errors in execution that compromise the quality of the data. GCI has performed data quality reviews of a number of these tests and found numerous errors in the following areas: lab errors, calculation errors and sample contamination
Similarly, trace metals emissions test values may be suspect as well. These problems are generally due to errors in: lab errors, methodology errors and sample contamination.
Once the quality of the data has been established, a comparison of this data and the standard will quickly point out if your facility complies with the standard or if additional testing is required.
Preparing for the Emissions Tests
Performing the emissions tests should be straight forward, right? Just call up a stack emissions testing firm and schedule a date for a test. It=s not that easy.
First, you will need to look at the sampling location. Is it the best location for determining stack emissions? Does it conform to the standards set forth in the EPA methods? Are the ports large enough and properly located? Can the sample ports be accessed by the sampling firm with all of the equipment they'll need? Is there a reliable power source for the sampling firm's equipment? The best way to address these questions is to arrange for the sampling firm's technical service representative to visit the facility.
Next, you need to look at the conditions that should exist during the test. For hazardous waste combustors (HWC) where operating limits must be established, "sources will likely want to operate during the test at the edge of the operating envelope" (FR 61, page 17444). This is not dissimilar from a BIF test or a Trial Burn. For non-HWCs, the performance test requirements are less rigorous however. As an example, a maximum APCD inlet temperature may have to be established but not a maximum production rate. The language of the final ruling may be different from the proposed ruling, so be sure to determine the performance test operating requirements before you plan your test!
EPA's requirements for the semi-volatile metals (Cd and Pb) and the low volatile metals (As, Be, Cr and Sb) may allow for some adjustment due to their presence in the raw feed. To do this would require the determination of a system removal efficiency (SRE). SRE determination would require collection and analysis of feed and product samples. Even then, however, the analytical results must be above the lower detection limit, or the SRE values will likely be useless. Despite what the EPA has said, spiking may still be required for some metals (or an approved surrogate) to establish a "representative system removal efficiency." Again, this provision mildly advanced in the proposed regulation, might not be available in the final ruling. In any event, each facility should have a good idea of the SRE for each metal. This will help avoid surprises from subsequent non-compliant emission rates due to a source change for coal or raw materials. The trace metals mass balance used to determine the SREs is also a good way to check the quality of the metals emissions data.
Now that it has been determined which emissions are to be sampled, how and where the stack is to be sampled, and how and where process samples will be collected, an analytical laboratory (sometimes more than one), has to be selected. Be sure to pick those that are experienced with the sample matrix. Also, be certain that a full QA/QC data package is included as part of the analysis. Additionally, get a firm commitment on sample turnaround: the time from receipt of sample to analytical report. This turnaround time may end up being more important in setting the date for the test than any other factor.
Performing the Emissions Test
If you have planned properly, the execution of the test is relatively straight forward. Since the system must operate at the "edge of the operating envelope", a series of practice runs at these operating parameters are highly recommended. Maintaining these conditions over the required sampling periods can be difficult. Even for the non-HWC facilities operating at the desired APCD maximum inlet temperature may be difficult to sustain. Consequently, it is well worth your while to execute the test runs as expeditiously as possible. Many stack sampling firms like to schedule only two runs a day, or only provide enough manpower to operate one or two sampling trains. This may be less expensive, as far as the cost of collecting the stack samples is concerned, but it stretches the test period out leaving more time for problems to develop. This also increases run to run variability.
In addition, the facility should have an experienced supervisor in charge during the test, someone who can anticipate operating problems and head them off before these problems impact the test. It is also best to have your environmental compliance manager keeping tabs on the sampling contractor and comparing what the contractor is measuring as stack gas flow rates, temperatures, moisture, etc. versus what the facility operating conditions deem these to be. Clearly, large discrepancies would indicate a problem with one or the other. Murphy's Law respects neither your planning nor the expense of a retest.
Post Test Activities
Evaluate the analysis and sampling contractor's data for quality. Look for such things as:
GCI is experienced in writing stack emission test plans and managing emission testing. GCI has also evaluated emissions test data for major corporations. If you require assistance in performing your MACT testing, please contact us.