Off-Site Consequence Analyses
Risk Management Program (RMP) provisions require an owner or operator of each stationary source subject to the 40 CFR 68 requirements to develop a Risk Management Plan. Risk Management Plan must be prepared following the standard format developed by U.S. Environmental Protection Agency (EPA). Plans must include Worst-case and Alternative Off-site Consequence Analyses (OCA) for all or selected representative Regulated Processes. The number of OCA’s included in each Plan depend on the type of RMP-regulated chemicals handled at the stationary source (i.e., toxic or flammable substances) and the number of chemicals of each type contained in Program 1, Program2, and/or Program 3 TRI-regulated processes.
In addition, all OCA assumptions and calculations are to be documented per the 40 CFR 68 provisions, and the documentation is to be kept on-site.
Sage Environmental personnel have extensive experience in preparation of Risk Management Plans for stationary sources containing from one to dozens of PRM-regulated processes and in completion of simple and complex Off-site Consequence Analyses.
The RMP regulation is necessarily complex and often confusing. The areas that require significant time and accuracy duringthe preparation of a Risk Management Plan include development and proper documentation of the worst-case and alternative OCA's for the minimal required number of scenarios for toxic and/or flammable substances. The endpoint distance for each RMP-regulated process defines the Prevention Program level of the process. Overestimated endpoint distances may result in triggering Prevention Program 2 or Program 3 requirements, enhances attention to the process operations from public, and unnecessary increase in environmental liability in case of an accident resulting in a release of the RMP-regulated substance(s).
EPA and commercial and non-commercial organizations provide multiple tools for completion of OCA’s. Examples of such tools include a simplified RMP*Comp software developed by U.S. EPA and most often used by plan preparers and complex air dispersion models that more accurately estimate endpoint distances for specific release scenarios (e.g., release of a toxic liquid in a pool with following evaporation) and specific characteristics of released materials (e.g., dense gases).
Sage personnel have extensive experience in completion of simple and complex Off-site Consequence Analyses using RMP*Comp, Aloha, DEGADIS, SLAB, and other computer models. The personnel have thoroughly studied the EPA’s “OCA Guidance” and often use equations provided in the guidance in lieu of simplified but often unnecessarily conservative computerized calculations.
For a complex Stationary Source that potentially contains multiple RMP-regulated processes (e.g., a petroleum refinery), Sage typically starts OCA’s from a review of the existing plan and interviewing the on-site personnel. The primary goal at this step is to ensure that all toxic and flammable RMP-regulated materials are identified and that the amount of each applicable material is appropriately estimated for each largest vessel or piping segment in each process. Subtasks if this task may include:
- establish process boundaries within the stationary Source;
- create a list of all significant process vessels, including vessel volumes;
- document regulated substances, including flammable mixtures, in each vessel;
- document applicable material component concentration ranges;
- document theoperating parameters (e.g., the maximum controlled liquid level, temperature, and pressure);
- calculate the maximum quantity of each RMP-regulated substance in a single vessel.
Completion of OCA for each process is then completed for each process to define whether the process in Subject to RMP Program 1 or Program 2/3 requirements. The worst-case and alternative release scenarios assumptions and calculations are documented. A simplified RMP*Comp software developed by U.S. EPA is most often used by plan preparers to estimate the end-point distances. Sometimes, refined modeling using more sophisticated programs may benefit the Stationary Source. If such occasion is identified, Sage Environmental completes refined modeling upon consultation with the client.
Sage Environmental personnel completed dozensof RMPlan documentation and submission projects. References are available upon request.