Coalition for Responsible Waste Incineration

April 23, 2001

Program Evaluation, Records, & Information Services Branch
1600 Clifton Road
Atlanta, GA 30333

Dear Sir/Madam:

The Coalition for Responsible Waste Incineration (CRWI) is pleased to submit comments on the draft document Public Health Reviews of Hazardous Waste Thermal Treatment Technologies (66 FR 16248, March 23, 2001). CRWI represents twenty two companies with hazardous waste combustion interests. These companies account for a significant portion of the U.S. capacity for hazardous waste combustion. In addition, CRWI is advised by a number of academic members with research interests in hazardous waste combustion. As such, CRWI is a unique technical resource on combustion. CRWI seeks to help its member companies both to improve their combustion operations and to work constructively with lawmakers and regulators to develop effective and workable policies and rules that ensure protection of public health and the environment.

For the most part, CRWI believes that the document is well written and contains important information that public health officials should consider when reviewing the use of incinerators or thermal desorbers to destroy hazardous waste or decontaminate soil or debris. However, there are a several areas where we believe the report can be improved. CRWI believes the utility of the report could be greatly increased by adding an Executive Summary. Another problem is that one of the most useful parts, the case studies, are placed at the back of the report and are not significantly discussed or referenced in the body of the text. We suggest that the document can be significantly improved by adding an Executive Summary and including a summary table of the case studies in that Executive Summary. To this end, we have included a draft summary table in specific comment 12. While we did not attempt to fill in the table for all the case studies, we did develop a draft for the first two studies. Hopefully, this will give the agency sufficient guidance to fill in the information for the other case studies. By adding an Executive Summary and using a table such as the one suggested, we believe that the reader will more easily understand the general concepts developed in the document.

Specific comments are as follows:

  1. 3.1 (page 9 of 95). ATSDR makes the statement that it believes that a properly designed and operated thermal treatment technologies can effectively and safely destroy or decontaminate certain types of hazardous waste. CRWI agrees. In fact, the information in most of the case studies also agrees. We suggest that the agency use this as a place to reference the case studies. This would tie these two portions of the guidance closer together and place a reference to one of the more important parts of the document close to the beginning of the document.
  2., second bullet (page 23 of 95). The meaning of this bullet is difficult to understand. Emissions from hazardous waste combustors are controlled in a number of ways (e.g., operation parameters, CEMs, feed rate controls, etc). Once limits have been established based on the results of testing, it is not necessary to set automatic waste feed shut off trigger limits "well below" those limits. This defeats the very purpose of using tests to set these limits. Perhaps we have misunderstood the purpose of this bullet and suggest that this bullet be clarified.
  3. (page 29 of 95). ATSDR states that "performance tests should be run at the middle-to-end of the carbon adsorption units change-out cycle." CRWI believes that there are fundamental flaws in this logic. First, this requirement is impossible to accomplish upon startup since it is normally not possible to start the first time at the middle or end of a carbon change-out. Second, the newly promulgated hazardous waste combustor (HWC) MACT rule (September 30, 1999, Part 63, subpart EEE) creates a series of tests for carbon systems that will be used to define the life of each system. In this rule, carbon systems will be tested at least every 2.5 years, some more often, depending upon the design of the system. Third, this statement assumes that the efficiency of carbon absorption units deteriorates over time. Carbon injection systems continually inject fresh carbon. Thus, the capture efficiency of these systems should not be impacted by time. Carbon beds are designed and built to maintain their capture efficiency at a stable level until all the absorption sites are filled. When this happens, then a "break through" of pollutants occurs. Incinerators must show 99.99% destruction of organic materials before they can operate. Thus, the organic loading on carbon beds for incinerators is low and their theoretical life can be as long as hundreds of years (Note that this portion of the comments only applies to incinerators. Thermal desorbers may have a lower destruction efficiency and may have a significantly shorter theoretical life). The limiting factor for these carbon beds will be plugging of the initial stages by particulate matter. This will occur long before the theoretical "break through" point is reached. When the system starts to get plugged, as evidenced by the difficulty of forcing air though the carbon bed, the system is shut down, cleaned and new carbon is added. Since new carbon has just been added, the time to "break through" starts back at zero. Based on this information, CRWI suggests that ATSDR modify this section to allow for the carbon bed age to be determined based on site-specific conditions.
  4. (page 30 of 95). The first sentence suggests that facilities whose risk assessment show a potential for release of contaminants to the atmosphere at concentrations which may cause adverse health effects should be required to have an ambient air sampling and monitoring plan. CRWI suggests that this may not be appropriate in all cases. First, it should be noted that if a risk assessment shows a potential for a release to the atmosphere that would be harmful, a permit would not be issued. Without the permit, that facility cannot operate and there would be no need for an ambient air sampling and monitoring program. Second, previous work has suggested that the contributions from HWCs to ambient concentrations are very small. WTI (East Liverpool, OH) has been one of the most studied hazardous waste combustors. This facility conducted a number of ambient air tests and attempted to develop a correlation with stack emissions. Based on worst case dispersion models from stack concentrations, the contribution from this facility to the ambient air concentration of chromium and manganese was less than 0.5% and 0.03%, respectively. While ambient air concentrations have to have a source of the contaminants, the contribution from most hazardous waste combustors is likely to be so small that a meaningful correlation cannot be developed. There are simply too many other, larger sources for HWCs to be a significant contributor to ambient air concentrations. Therefore, CRWI suggests that the language be modified to recognize that ambient air monitoring decisions should be made on a site-specific basis.
  5. (page 35 of 95). ATSDR strongly recommends that both CO and HC CEMs be on the stack during testing. In the newly promulgated HWC MACT rule, the only time both instruments are required is during DRE (destruction and removal efficiency) testing. Having both CEMs on the stack during metals test runs would not add useful information to the test data. CRWI suggests that ATSDR modify this requirement to match the current requirement in Part 63, subpart EEE (both CO and HC CEMs required during DRE testing only).
  6. 6.2.3 (page 37 of 95). ATSDR appears to recommend that CERCLA and new RCRA facilities not be allowed to operate until the results of the performance test are reviewed and final operating parameters are established. CRWI strongly opposes this recommendation. This is not necessary or desirable and is not consistent with current RCRA practice. HWCs have shown in the past that they can safely operate using conservative operating conditions. In addition, RCRA permits can take years to obtain (the current record is 15 years operating in interim status). Using the results from the case studies included in this report, one could conclude that even a poorly operated incinerator would pose little or no health risk to the public. Thus, operating an incinerator under conservative operating conditions would pose even less risk to the public. This requirement could add months to the time it takes to clean up a site. The relative risk for leaving a site contaminated while waiting for approvals and a permit is much greater than initiating cleanup and operating a HWC under conservative operating conditions. CRWI suggests that ATSDR remove this recommendation from the report.
  7. (page 41 of 95). CRWI disagrees with the exact language of this section concerning ambient air measurement data and air sampling data. We agree that the measurements taken over a protracted period are more reliable for assessing the "total" exposure of a hypothetical individual located near the monitor (for the specific chemicals measured--which, though obvious, should be stated). However, unless that data are correlated and/or analyzed in conjunction with meteorological data and emissions data for the same time period from particular sources, the ambient data is weak for evaluating relationships between the exposures and the possible sources. CRWI suggests that this paragraph be reworked to clarify the need for precision in matching measurements to objectives for studies.
  8. Chapter 7 (page 41 of 95). The third bullet mentions RCRA combustion regulations. The regulations cited are Clean Air Act regulations, not RCRA regulations. CRWI suggests changing this language to reflect the citation (hazardous waste combustor MACT).
  9. Chapter 7 (page 42 of 95). The sixth bullet suggests using a declining DRE during a TRV event. CRWI is not aware of any data on which to base such an assumption. If the agency has data for this, CRWI suggests that a reference to that data be added to the document. If not, CRWI suggests that any change in the DRE during a TRV event will depend upon a number of site-specific design criteria (e.g., how fast the unit cools, how much draft the TRV allows, etc). CRWI suggests that either this sentence be deleted or that any reference to changes in DRE during a TRV event be decided on a site-specific basis.
  10. 8.1.4 (page 51 of 95). There are a number of errors in the description of the Times Beach incinerator. The unit was "direct-fired" not "indirect-fired," the emergency vent was between the primary and secondary combustion chambers and not after the secondary combustion chamber, and the scrubber was "hydrosonic" not "ultrasonic." CRWI suggests correcting these errors and recommends that the facility descriptions for the other case studies be checked.
  11. Table 7 (page 85 of 95) shows a mercury removal efficiency of electrostatic precipitators (ESP) of 0%. One member (Lafarge) has trial burn data that shows mercury removal efficiency for an ESP of 50 to 60%. While ESPs are not specifically designed for this purpose, some systems do remove significant amounts of mercury. CRWI does not suggest changing the table but does suggest adding a footnote that states that some sources may have appreciable mercury removal from their ESP.
  12. Example Summary Table for Executive Summary of ATSDR Report.
Section Location(date) Source Type Initial Concern Study Design Overview of Conclusions
8.1.1 Caldwell Co. SC HW Incinerator Worker and Neighbor Exposure Retrospective Cross-sectional;Symptom and Disease Prevalence Increases in self-reported symptoms; NSD for self-reported and physician-diagnosed disease
8.1.2 Caldwell Co. SC HW incinerator Worker and Neighbor Exposure-Follow-up Study Retrospective Cross-sectional; Symptom and Disease Prevalence Some increases in phlegm prod. And wheezing; NSD in pulmonary function tests, nor immune assay tests

Thank you again for the opportunity to comment on this document. If you have questions about these comments, please contact me (202-775-9869 or

Sincerely yours,

Melvin Keener, Ph.D.
Executive Director

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