Aqualon - Kenedy, Texas Plant - Executive Summary |
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RMP EXECUTIVE SUMMARY SCOPE Hercules, the Kenedy, Texas plant has established a Risk Management Program (RMP) covering the safe use of propylene oxide and measures to take if propylene oxide were to be released. The following Executive Summary briefly describes our policies regarding Responsible Care issues directed toward safe handling and use of chemicals, the Bulk Chemical Unloading and storage area which is the only covered process on site, the worst case and alternative case scenario, 5 year accident history as it relates to propylene oxide releases, the accidental release prevention program, the emergency response program, and planned changes to improve the safety of the propylene oxide bulk chemical unloading and storage system. POLICIES Hercules Incorporated is dedicated to providing a safe and healthful environment for our employees, customers, and communities. To do this, we are dedicated to and working towar d continuous improvement in our operations to prevent pollution, to reduce risk: and to enhance safety, health and environmental performance. In accomplishing these goals, Hercules, Incorporated has maintained membership with the Chemical Manufacturer's Association and practices Responsible Care at all facilities including Kenedy, Texas. All management practices associated with Responsible Care Program compliance are reviewed annually to assure all provisions are in place and operational. STATIONARY SOURCE Propylene oxide is handled in one process above the threshold quantity at the Kenedy, Texas plant. This area is named the bulk chemical storage and unlaoding area. Typically, propylene oxide is delivered to our plant biweekly in tanker trucks which carry approximately 44, 000 pounds each. The truck is parked in the unloading area using procedures that assure the chemical holding portion of the truck is within the protected area. The protected area has a trench around the peri meter which is intended to catch any releases of propylene oxide. The trench drains to a concrete lined neutralization pit where it can be pumped to another container or otherwise controlled. The truck is hooked up to our unloading system using dry disconnect, 2 inch, stainless steel wire wrapped, flex hoses. Dry disconnect hoses prevent the release of chemical as the hoses are conneced or disconnected. Propylene oxide is pumped from the truck to the holding tank through stainless steel pipe. All vapor associated with the unloading procedure is vented back to the truck with no releases to the atmosphere. The storage vessel holds approximately 120,000 pounds of propylene oxide. The tank sits withing a concrete containment dike which is inspected annually to assure the containment will not leak if propylene oxide is spilled. Specific propylene oxide unloading procedures are in place to assure all emergency equipment is functional prior to unloading and that the pumps and system are leak free. Specific carriers are hired that have dedicated propylene oxide trailers that have manual shut off valves, excess flow valves that stop the flow if the flow exceeds a normal amount, and hydraulic lines that can be tripped on the way out of the area to stop the flow. The hydraulic line is in front of the trailer and once tripped, the internal valve in the unloading line closes shuting off chemical flow. All operators are certified in the unloading operation and are required to stay within 25 feet of the truck while unloading is taking place. WORST CASE SCENARIO The worst case scenario is to have a castrophic failure of the storage tank while the tank is full (120,000 pounds). This type of an occurrence has a very low likelihood of actually happening; however, following EPA requirements for calculating the worst case scenario, the full contents of the tank would be released in a 2100 square foot containment pad in a 10 minute period. A temperature of 107 f. and a wi nd speed of 1.5 meters per second were used in the calculations of vapor dispersion. Because of the 2100 square foot area of the spill, propylene oxide is released (vaporizes) at a rate of 155 pounds per minute. The EPA toxic endpoint for propylene oxide is 0.59 milligrams/liter or 250 parts per million (ppm). The Immediately Dangerous to Life and Health (IDLH) is 400 ppm which allows 30 minutes to leave the area without risk of permanent health effects. The 250 ppm allows approximately 1 hour to leave the contaminated area or to lessen the exposure by "sheltering in place". Dispersion modeling was completed using SLAB software. SLAB was developed by Lawrence Livermore National Laboratory and is capable of handling vertical or horizontal jet releases or ground level evaporating pool or passive area source releases. Results of the worst case scenario indicate vapor from evaporating propylene oxide would migrate off site to an end point 0.44 miles from the spill area. It is antic ipated off site consequences could occur. ALTERNATIVE CASE SCENARIO An alternative case scenario was developed as a more tangible occurrence although the likelihood of occurring is still very low. Mechanical integrity, materials of construction, preventative maintenance, hazard analysis, operator training, management of change, permit to work programs and other such programs developed and instituted at the Kenedy Plant limit the potential of any such occurrence. The alternative case release consists of a 2 inch truck unloading line break in a contained area. All material is captured in a trench which then drains to a neutralization pit. The release is stopped by an onsite HAZMAT trained emergency response team in 10 minutes. It is anticipated that in an actual incident, the operator would shut off the flow from a leak by any one of the three shut off devices located on the trailer on his way out of the area which would limit the spill to less than 10 minutes, but for this scenar io, a 10 minute time is used. The spilled propylene oxide is released at a rate of 613 pounds per minute. We see a larger rate of release from this scenario than the worst case scenario because the spill would cover a larger surface area, exposing more surface area of propylene oxide to heat would cause more propylene oxide to evaoprate. Average local temperature (77 f.) and wiind speed (4.34 m/s) are used in the SLAB calculations for vapor dispersion modeling. The resulting model indicates vapor migrating to a 250 ppm endpoint 0.094 miles (approximately 500 feet) from the spill location. Based on this information, offsite consequences could occur. ACCIDENTAL RELEASE PREVENTION It is important to note that unloading hoses are not pressurized, other than to equalize pressure between the tank and the truck during the unloading process. Pumps are located after the hoses and therefore, draw propylene oxide through the hoses rather than pressuring through the hoses. Hoses are check ed for leaks before each unloading both by visual inspecting and pressure testing. Additionally, certified operators are trained to use the emergency hydraulic shut off system associated with dedicated propylene oxide trucks which would stop the discharge within a few minutes of the occurrence. If this procedure fails, the operator is in direct radio contact with safety personnel on site who would then turn in an emergency page to the trained emergency response unit. Immediate response to the situation would occure using Incident Command procedures. 5 YEAR ACCIDENT HISTORY Hercules Kenedy has not had a reportable propylene oxide spill in the last 5 years. PLANNED MODIFICATIONS Present projects to improve the safety of the bulk chemical storage and unlaoding area call for the installation of excess flow valves at the tank distribution line, automatic cutoff valves at the tank for remote or sensor activated shut down, sensors to detect leaks in the system with remote and area alarms , and replacement of diaphragm pumps with centrifugal pumps. |