St. Clair Underground Storage/MFP - Executive Summary
Executive Summary |
1.Accident Release Prevention Program and Emergency Response Policy
St. Clair Underground Storage d/b/a/ Marysville Underground Storage Terminal (MUST) and Marysville Fractionation Partnership (MFP) are committed to employee and public safety. It is our policy to implement the requirements of this Risk Management Program (RMP) in accordance with the USEPA regulations under 40 CFR Part 68 and with the corresponding regulations under OSHA's Process Safety Management (PSM) program and adhere to applicable federal, state, and local laws. This commitment is demonstrated by the resources invested in accident prevention such as the training of personnel and consideration of safety in the design, installation, operation, and maintenance of our processes. Our policy is to prevent releases of substances. If a release does occur, the operator's personnel, supplemented by local fire department will respond to control the effects of the release and to evacuate potentially af
fected personnel if needed.
2.Description of the Stationary Source and Regulated Substances
CMS Energy, with corporate office in Dearborn Michigan, is the principal partner for MUST and MFP located in Marysville, Michigan. Marysville Gas Liquids Company (a CMS Energy subsidiary) is responsible for the continuing operation and maintenance of the facility. MUST consists of ten underground caverns for storage of liquid hydrocarbon. Inbound and outbound deliveries are accomplished by tank truck, rail car and connections to nine liquid product pipelines. Various LPG, natural gas liquids and refinery liquid streams can be processed into five commercial products (i.e., HD-5 propane, normal butane, iso-butane, C5 - C6 fuel and C7 + fuel) through the fractionation process. The materials processed at Marysville are highly flammable and a sufficient quantity is present such that the requirements of 40 CFR Part 68 (RMP) apply. In addition, ethyl mercaptan, which is added to the propane as
an odorant is stored in quantities exceeding the threshold quantity. In certain cases toxic compounds (i.e., hydrogen sulphide, methyl mercaptan) are present as contaminants in either the feedstock or the products but none of the toxics exceed the threshold quantity. Therefore, two processes (pentane storage and LPG material storage and handling) with flammable substances are subject to RMP requirements.
3. Worst-Case and Alternative-Release Scenarios
There are two processes subject to RMP; Pentane plus storage and Flammable liquid (propane) handling and storage. Both processes are evaluated to determine the worst case scenario.
a.Flammable Liquid (Pentane)
In May 1999, EPA issued a direct final rule revising the worst-case release scenario analysis methods for regulated flammable substances. The most recent changes allow the facility to consider passive mitigation (i.e., containment) for flammable liquids at ambient temperature. Pentane is normally liquid at ambient temper
ature. Therefore, it is assumed that the entire quantity in the vessel is spilled instantaneously to form a liquid pool. The release rate to the air is the volatilization rate from a pool that spreads out into a diked area. The total quantity that becomes vapor in the first ten minutes is reported as the quantity released that is available for a vapor cloud explosion. Other assumptions for the worst-case analysis included: 10% of the flammable vapor in the cloud is assumed to participate in the explosion (i.e., the yield factor is 0.10). Mathematical algorithms were used to determine the distance to endpoint at an overpressure level of one pound per square inch (psi), with a wind speed of 1.5 meters/sec and the atmospheric stability being classified as F (stable). The nearfield dispersion environment was determined to be "urban" in accordance with the requirements of 40CFR 68.22(e). The results of the assessment for the pentane storage tank show that the 1 psi overpressure endpo
int occurs at a distance of 0.42 miles from the release point. There are public receptors within the distance to the endpoint.
b. Flammable Gases (Propane)
According to EPA's RMP guidance for facilities storing and processing flammable substances that are normally gases at ambient temperature, the worst-case release scenario is failure of the largest storage tank when filled to the greatest amount allowed (88% at 60F for propane), which then results in a vapor cloud explosion. The entire contents of the cloud is assumed to be within the flammability limits, and the cloud is assumed to explode. For the worst-case analysis, 10% of the flammable vapor in the cloud is assumed to participate in the explosion (i.e., the yield factor is 0.10). Consequence analysis algorithms were used to determine the distance to the endpoint at an overpressure level of one pound per square inch (psi). Other assumptions for the worst-case analysis included: the storage vessel is not diked; no passive
mitigation system is in place; the nearfield dispersion environment is characterized as urban; the wind speed is 1.5 meters/sec and the atmospheric stability is classified as F (stable). The results of the worst-case assessment for the propane bullet tank show that the 1 psi overpressure endpoint occurs at a distance of 0.56 miles from the release point. There are public receptors within the distance to the endpoint.
The selected alternative-release scenario for the facility is a release that occurs as a result of a leak in the propane dryer. To estimate the impact distance for this alternative-release scenario, a vapor cloud fire was assumed to occur. The distance to the Lower Flammability Limit (LFL) represents the maximum distance at which the radiant heat effects of a fire might have serious consequences. The LFL for propane is 36 mg/L (EPA guidance document). ENSR assumed that propane is a dense gas and that the nearfield dispersion environment is determined to be urban.
There are public receptors within the distance to the calculated endpoint (0.1 miles).
4. General Accidental Release Prevention Program and Chemical Specific Prevention Steps
The processes are subject to the OSHA PSM standard. Therefore, they are subject to Program 3 of 40 CFR Part 68. This requires planning and facility activities intended to prevent a release of hazardous material, or if a release inadvertently occurs, to minimize the consequences of a release to the employees of the facility, the public and to the environment.
The facility is governed by a set of federal and state regulations that require planning and facility activities intended to prevent a release of hazardous material, or if a release inadvertently occurs, to minimize the consequences of a release to the employees of the facility, the public and to the environment. These regulations include:
? 29 CFR Part 119, Process Safety Management
? 40 CFR Part 68, Chemical Accident Prevention Provision
Fire Protection Association 58
? API Recommended Practice 750
? 40 CFR Part 112, Spill Prevention, Control and Countermeasure
? 40 CFR Part 264, Hazardous Waste Contingency Plan
? 49 CFR Part 195, Transportation of Hazardous Liquids by Pipelines
Employee participation in the release prevention program is encouraged and supported by Marysville Gas Liquids management. Key personnel are responsible for conducting and implementing the findings from the Process Hazard Analysis (PHA).
MUST/MFP's policy is to construct all new equipment, systems, and facilities in accordance with the most current building and safety codes. This ensures the appropriate safety and release prevention systems are included from the beginning of each project. A computerized program of maintenance activities is in place to ensure that key systems are maintained appropriately to minimize the risk of a release.
Marysville Gas Liquids is committed to providing appropriate training to all employees regarding safet
y procedures. New employees are provided comprehensive safety training during their initial orientation for the facility. In addition, Marysville Gas Liquids conducts regularly scheduled safety training for all employees each year. Additional training is provided to maintenance personnel for the systems they are responsible for.
5. Five Year Accident History
Marysville Gas Liquids has not had a release of flammable substances from regulated processes that has affected the public or the environment. Therefore, there have not been any releases that meet the reporting criteria specified by 40 CFR 68.42 (a).
6.Emergency Response Program
Marysville Gas Liquids has personnel trained in emergency procedures at the facility 24 hours per day, seven days per week. An emergency response program has been developed and updated as necessary to reflect the current operations at the Marysville facility. In addition, the facility's emergency response program is incorporated into the St. Clai
r County Emergency Management Response Plan.