Black Lake Gas Plant - Executive Summary |
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Executive Summary HLP Engineering, Inc. has developed this Risk Management Plan for Exco Resources, Inc.'s Black Lake Gas Plant in accordance with 40 CFR part 68. The facility is subject to the requirements of this program due to the production and storage of natural gas liquids (NGL) containing over 10,000 lbs. of regulated flammable substances. The facility is located in a remote section of Natchitoches Parish approximately 6 miles southwesterly of Goldonna, LA. Public access to the facility is restricted. Surrounding property is privately owned timberland. The facility processes crude oil and natural gas from nearby field tank batteries and produces NGL from the natural gas stream. Wet field gas is first treated to remove acid gas components and is then routed to a refrigeration unit. The low temperature of the refrigeration unit causes the NGL to separate from the gas stream. The liquids are then routed to a three phase cold separator and demethanizer for further p rocessing. Finally, the NGL mixture is stored in a 4000 BBL pressurized surge tank and sold by pipeline. The threshold quantity for all flammable substances under 40 CFR part 68 is 10,000 lbs. The total amount of NGL in the cold separator, demethanizer and surge tank is approximately 19,644 lbs. The NGL contains a mixture of methane, ethane, propane, butane, pentane and other heavier hydrocarbons. An analysis of the product shows that the concentration of regulated substances in the mixture is greater than 1 percent by weight therefore the entire quantity of NGL was included in the threshold determination. A worst-case release scenario involves a tank failure due to a 1-psi overpressure resulting in a vapor cloud explosion. The scenario assumes failure of all safety devices and a release of the product within the tank as well as in the connecting vessels. The distance to the endpoint for an explosion of 19,644 lbs. of NGL is 0.2 mile. According to USGS maps and operator kno wledge of the area there are no public or environmental receptors within a 0.2-mile radius of the facility. The closest receptor is a private residence located 0.4 mile from the facility. The residential population within the worst-case circle is estimated to be zero. The 4000 BBL NGL surge tank is equipped with a relief valve that vents to a closed-loop burning flare and automatically operates according to preset pressure specifications. Also, a low-level alarm system is installed on the tank that activates when the level in the tank drops to approximately one-third of the total tank capacity. An alternative release scenario involves the activation of the low-level alarm due to either a faulty relief valve, pipe breakout, or pump seal/packing leak. Once this alarm sounds it could take facility personnel 2 to 5 minutes to respond by manually closing a valve that shuts-off the flow from the demethanizer to the surge tank. In this event it is possible that the entire volume of t he surge tank (15,364 lbs. of NGL) would be released. The distance to the endpoint for a release of this amount of NGL is also 0.2 mile. The facility has not experienced a release that caused on or off site injury, death or property damage within the past five years. This facility qualifies as a Program 3 facility because it is subject to the OSHA Process Safety Management regulations in 29 CFR 1910.119. Exco Resources, Inc. has developed and continuously implements the prevention program required by OSHA. All documents that verify compliance with the OSHA and RMP requirements are maintained within the Black Lake Gas Plant field office. Exco Resources, Inc. has developed and implemented an emergency response plan for the Black Lake Gas Plant. This plan is located on-site and is coordinated with the Natchitoches Parish Sheriff's Office and the Goldonna volunteer fire department. |