Coalition for Responsible Waste Incineration

RCRA Information Center
Office of Solid Waste (5305G)
USEPA HQ
401 M Street, SW
Washington, DC 20460

RE: Docket F-1999-SLRA-FFFFF

The Coalition for Responsible Waste Incineration (CRWI) is pleased to submit comments on the Screening Level Ecological Risk Assessment Protocol for Hazardous Waste Combustion Facilities (EPA530-D-99-001A, August 1999). CRWI represents ten companies that operate hazardous waste combustion units and eight other companies with interests in hazardous waste combustion. 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. Since its inception, CRWI has encouraged its members to reduce the generation of hazardous waste. However, for certain hazardous waste streams, CRWI believes that combustion is a safe and effective method of treatment, reducing both the volume and toxicity of the waste treated. CRWI seeks to help its member companies both to improve their operations and to provide lawmakers and regulators helpful data and comments.

CRWI is concerned about three aspects of the current use of site-specific risk assessments. First, if site-specific risk assessments are to be required for all hazardous waste combustors, CRWI believes that EPA has to promulgate a rule requiring them. This has to be a formal rulemaking that follows all the requirements of the Administrative Procedures Act. It cannot be done as part of a strategy document, guidance, policy, or by memo. Second, if site-specific risk assessments will not be required for all hazardous waste combustors, CRWI believes that EPA should develop detailed criteria (with supporting documentation) to base decisions on which facilities will be required to develop a site-specific risk assessment and which will not. Without these criteria, the choice of developing a risk assessment for a facility can be arbitrarily made. Third, all the site-specific risk assessments that have been completed on hazardous waste combustors have shown that the facilities are protective of human health and the environment. CRWI believes that past results should influence future decisions on the need for site-specific risk assessments. Risk assessments are expensive endeavors whose use, if not needed, should be minimized.

In addition, CRWI is concerned about how site-specific risk assessments will be used now that the hazardous waste combustor MACT rules have been promulgated. EPA performed risk assessments for approximately 40 incinerators and the MACT standards were shown to be protective by those risk assessments, even with excessively conservative assumptions. CRWI believes this large number of risk assessments adequately demonstrate that the current MACT standard are protective of human health and the environment.

CRWI believes that realistic risk assessments can be used as a tool to reassure the regulating agencies and the public that their hazardous waste operation is safe and protective. However, CRWI does not believe that risk assessments should be used to set individual permit limits that are more stringent than the current standards except under unusual conditions. These standards have already been shown to be protective of human health and the environment. The only circumstance where CRWI can envision using risk assessments to further restrict permit conditions is where a realistic risk assessment shows an unacceptable risk and an omnibus determination can clearly be documented. In addition, CRWI does not believe that risk assessments should be routinely used as permitting tools unless the risk assessment protocols are subjected to the rigors of validation.

In an effort to develop more realistic ecological risk assessments, CRWI offers the following comments on the draft guidance document. In reviewing the document, Four general concerns were found. They are:

1. CRWI is very concerned that portions of this model have little or no theoretical basis. For example, in Chapter 5, a bioconcentration factor (BCF) for daphnia is developed using three chemicals. The guidance then takes this BCF and applies it to all chemicals and to a number of aquatic and non-aquatic invertebrates. This type of extrapolation has no basis in science. Pathways where there are no bioaccumulation data should not be included in the model until additional research can be conducted establishing appropriate bioconcentration factors. CRWI strongly suggests that these pathways be removed until additional data can be developed. Additional examples will be identified in the specific comments (attached).
2. CRWI is concerned about the lack of validation for all parts of this model. While parts of the model (the air dispersion portion) have been in use for a number of years and continually gets refined, the Agency has yet to rigorously validate any of the models in this guidance. CRWI believes that until a model is validated against actual data, all model calculations should be viewed with suspicion. While a non-validated model can be used for sensitivity analysis, it should never be used to estimate actual risk. The Science Advisory Board (SAB) has made this suggestion to EPA at least two times in the past. CRWI agrees with the SAB and suggests that the Agency make a concerted effort to validate as much of these models as possible prior to their use as a permitting tools.

3. CRWI is concerned with the way "upset conditions" are used in the model. EPA makes the assumption that "upset conditions" will result in increased emissions. This assumption has no basis in fact. CRWI presents data in these comments to show that in at least one case, "upset conditions" do not result in increased emissions. CRWI believes that any use of "upset conditions" should be confined to the uncertainty section of the risk analysis until data shows otherwise. CRWI also believes that the use of upset factors to scale-up emissions should be dropped until data can be produced to prove that such scale-up factors are appropriate.
4. CRWI is concerned about the internal consistency within the guidance document. The Agency, on one hand, does not allow any soil degradation despite having the same substances taken up by plants, eaten by animals, and ending up in the water supply through runoff and erosion. CRWI believes that this violates conservation of mass and is concerned that this may lead to double counting of those substances. Our specific comments address a number of these points. CRWI suggests that EPA carefully examine all the equations to ensure that the principles of conservation of mass are kept intact and that the terms and equations are used in a consistent manner throughout the guidance document.

Sincerely yours,

Melvin E. Keener, Ph.D.
Executive Director

NOTE: The attachment to this letter can be obtained by contacting CRWI.

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