NORTH CAROLINA PROTOCOL FOR PERFORMING INDIRECT EXPOSURE RISK ASSESSMENTS FOR HAZARDOUS WASTE COMBUSTION UNITS--JANUARY 1997

The "North Carolina Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units--January 1997" (the "NC Protocol") has been developed as a guidance document to assist facilities that are undertaking an indirect risk assessment as part of the hazardous waste combustion permitting process. This document is intended to provide a consistent methodology for all combustion permit applicants to use when considering the appropriate indirect pathways, scenarios and parameters for their particular facility. The NC Protocol is intended as a nonbinding interpretative statement and is not subject to rulemaking in accordance with G.S. 150B-2(8a)c.

The requirement for hazardous waste combustion facilities to conduct an indirect risk assessment as part of the permitting process originated in the draft Hazardous Waste Minimization and Combustion Strategy issued by Carol Browner in 1993. In this strategy, which was finalized in 1994, EPA set a policy for including indirect risk assessment considerations in final permit decisions for combustion facilities, especially the boiler and industrial furnace (BIF) facilities that have not yet been permitted. North Carolina contracted with Research Triangle Institute to develop the NC Protocol to help clarify the indirect risk assessment issue. Combustion facilities may use the NC Protocol as a guideline for this evaluation, or they may develop their own protocol, which will then be reviewed as part of the permit application.

EPA has implemented the indirect risk assessment requirement through 40 CFR 270.32(b)(2), also known as the "omnibus authority." This rule states that as a part of the permitting process, the Director can request any information required to assure the protection of human health and the environment. North Carolina also has authority per 15A NCAC 13A .0109(r)(1) & (2), which states that the Department will consider the risks posed by a hazardous waste management facility on "population centers" and "water supplies," as well as requiring protective measures to avoid unreasonable risks posed by "potential air emissions." The language in this rule clearly indicates that North Carolina must consider all routes of exposure to the surrounding community from air emissions, not just inhalation (or direct) exposure.

North Carolina expects the hazardous waste combustion facilities who must consider indirect exposures as a part of the permitting process to implement the indirect risk assessment process in much the same way as the direct risk assessment has been implemented in the past. Consideration of both the direct and indirect exposures must be reflected in the trial burn plan and demonstrated in the trial burn. Data from the trial burn will then be used to conduct the direct and indirect risk assessment to help establish safe and reasonable permit limits for the combustion unit. The indirect risk assessment procedure should be conducted in close consultation with the individual permit writers, in much the same way that the direct risk assessment and trial burn plan preparation is currently conducted.

As the document is used to develop indirect risk assessments, it is anticipated that the information gathered during that process will lead to continuing revisions of the January 1997 version of the NC Protocol. North Carolina will strive to keep the NC Protocol an "evergreen" and current document in order to provide the most useful tool to aid in the complicated indirect risk assessment process. Therefore, any comments a regulated entity or a member of the public has at any point in the permitting process for these combustion facilities will be considered and, if appropriate, included in the NC Protocol.

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