Halter Moss Point - Executive Summary
Halter Moss Point respectfully submits this Risk Management Plan (RMP) to meet the requirements of the Clean Air Act Section 112(r). This Halter Moss Point site is located at 5801 Elder Ferry Road,Moss Point, MS. 39567-8767 with geographic coordinates of 088 31' 40" longitude and 030 25' 30" latitude. Daily operational activities of this facility include the manufacture, fabrication, and repair of barges and marine vessels. Fabrication processes include steel plate processing, welding, painting, blasting and pipe fitting. The facility is regulated under the provisions of SARA Title III. Halter Moss Point is registered with a SIC code of 3731, and NAICS codes of 33661 and 336611. Halter Maine Group, Inc. acts as the corporate parent of Halter Moss Point. Halter Moss Point prides itself on being a vibrant member of the Moss point economy, providing jobs and products for economic expansion.
Halter Moss Point incorporates a comprehensive safety program in all standard o
perational procedures, which emphasizes individual responsibility. Each facility maintains a full time Safety / Environmental Manager to insure successful implementation of the program. A corporate Environmental Coordinator is responsible for directing company policy in a manner which emphasizes a firm commitment to the highest standards of safety for the regular employees, contract employees, subcontractors, visitors, and the surrounding population. While the corporate safety program covers many of the processes involved in shipbuilding, only the propane process on-site meets the threshold quantity (310000 pounds) requiring an EPA risk management plan under the Clean Air Act, section 112(r).
The propane is filled, serviced, and maintained by Blossman Gas, Inc., located at 2315 Telephone Road, Pascagoula, MS. Blossman Gas Inc. employees perform visually based safety inspections before each delivery. Each employee is trained based on experience and information from monthly training
sessions. The frequencies of the deliveries are variable, averaging about two per month. Company representative, Don Singleton, is responsible for administration of all documentation regarding tank maintenance. Maintenance is on an as needed basis, which is determined by the delivery driver's inspection. A certified service technician provided by AmeriGas performs all tank maintenance. The service technician is specially trained in propane tanks and distribution systems. The tanks are ASME (American Society of Mechanical Engineers) certified, using brass valves that are kept in the open position; to minimize wear. Emergency response procedures are reinforced through monthly training exercises. The delivery truck's propane transfer process is designed with both manual emergency shutdown or through pressure feedback features, so that only the amount in the hose can be lost during a transfer mishap.
The properties of propane, which contribute to its usefulness as a fuel, also c
ontribute to the need for safety precautions. Propane possesses a CAS# of 74-98-6, a molecular structure of CH3CH2CH3, a NIOSH/OSHA exposure limit of 1000 ppm, a lower explosion limit (LEL) of 2100 ppm, and a boiling point of negative 44oF. This low boiling point allows for rapid expansion from liquid to vapor thus producing extremely cold temperatures and the possibility of frostbite. Propane is liquefied under pressure and is stored and transferred in its liquid state. Propane is a colorless, odorless gas with a vapor density 1.5 times greater than air. Therefore it has a tendency to settle in low areas when released to the atmosphere. Foul smelling compounds are added to facilitate human sensory sensitivity as a safety consideration.
The explosive nature and useful fuel properties of propane are the same, ignition with an oxidizer, most commonly ambient air. It is therefore paramount that there are no devices or equipment that, because of their modes of use or operation are
capable of providing sufficient thermal energy to ignite flammable propane/air mixtures. The National Fire Protection Association, in conjunction with the propane industry, has promulgated NFPA 58 as a standard for safe storage and handling of liquefied petroleum gases.
Worst Case Scenario
The worst case release scenario for the facility would be a simultaneous failure of all two tanks (considered a single process) on site, causing the release of 22100 pounds of propane, (assuming all tanks were 80% full.) Blossman Gas, Inc. policy limits the maximum filling capacity of this tank to 80% at 60oF to allow for liquid expansion. It is assumed that the entire contents find a source of ignition, with only a portion in the resulting vapor cloud explosion. The estimated distance to 1 psi overpressure is 0.2 miles (0.4 kilometers). Within this distance there is a small residential population. It is assumed that the atmospheric stability class is F, when solar radiation is relatively wea
k and air near the surface has less of a tendency to rise resulting in less turbulence. In this case, the atmosphere is considered stable or less turbulent with weak winds. A wind speed of 3.4 miles/hour (1.5 meters/second) and a temperature of 77oC (25oC) is used with this scenerio.
Alternative Release Scenario
The alternative release scenario would be a transfer hose release under slightly different environmental parameters. The transfer hose is 150 feet by 1 inch in diameter, thereby releasing 25.94 pounds of propane. The estimated distance to 1 psi overpressure is 0.1 miles (0.16 kilometers). There is no offsite population within this area. It is assumed that the atmospheric stability class is D, representing conditions of neutral stability or moderate turbulence. Neutral conditions are associated with relatively strong wind speeds and moderate solar radiation. A wind speed of 6.7 miles/hour (3 meters/second) and a temperature of 77oC (25oC) is assumed with this scenario.
Accident History and Emergency Response
During the past five years there have been no accidents associated with the storage and/or use of the propane process. The emergency response for a release would include evacuation of the area and contacting the Local Fire Department. Any improvement to the propane storage or manifold system will be suggested and implemented by Blossman Gas, Inc.