The Gillette Company - Executive Summary |
|
Executive Summary For The City of Clarksville, TN Wastewater Treatment Plant In general, accidental release of chlorine is prevented through the education and training of plant personnel from their date at this facility. This is accomplished specifically with training in the following areas that includes, but is not limited to 1) proper handling of 1 ton chlorine cylinders (during loading and unloading of vendor conveyance) as well as elevated transit of containers to and from our chlorine storage/usage area, 2) proper installation and removal of valves and lines that convey chlorine gas from the chlorine vessel(s) to primary regulators, check units, and manifold assemblies, 3) service, maintenance, and calibration of chlorine leak detection and monitoring systems, 4) manual leak detection procedures (aqueous ammonia vapor application) at the container valves themselves, and 5) training in the proper use of the Self-Contained Breathing Apparatus (SCBA), 2 sets of which are maintai ned at the facility proper. This facility is a 15 MGD (maximum capacity) wastewater treatment plant which currently averages approximately 9 MGD. Wastewater at this site undergoes three major types of treatment carried out in a particular order to improve effluent quality. They are Mechanical, Biological, and Chemical in nature and are applied to achieve an acceptable end product to be released into our receiving stream. Disinfection is achieved through the use of chlorine gas injected into the effluent at the end of the process prior to being released to the effluent line (one mile in length) to subsequently empties into the receiving stream. Current inventory (stored in 1 ton cylinders) averages 8 full cylinders for a total of approximately 16,000 pounds of gaseous chlorine. For the purposes of this report, our worst-case scenario consists of a gas release resulting from a breach in the skin of a 1 ton cylinder (approximately 2,000 lbs. of gaseous chlorine). The release rate i s approximately 200 pounds per minute and the release lasts for about 10 minutes resulting in the release, to the environment of the entire vessel's capacity. Using the EPA's RMP Guidance for Waste Water Treatment Plants Reference Tables or Equations, it was determined that in an urban area with an Atmospheric Stability Class of F, and a wind speed of 1.5 meters per second, the distance to endpoint is 1.30 miles. The estimated residential population within this area is 4,385. This model, though thought to be accurate, does not take into account the mitigating effects of the enclosure which houses the chlorine vessels or a dike (primarily for flood control) around the entire facility. It is assumed that the enclosure would slow the release of the chlorine to the environment and the dike could serve to contain it somewhat, though the amount of mitigation has not been determined at this time. The alternative release scenario consists of a gas release resulting from pipe failure adj acent to the valves on a 1 ton cylinder (approximately 2000 lbs. of gaseous chlorine). The release rate is approximately 9.0 pounds per minute and lasts for 60 minutes. This results in a release of approximately 540 lbs. of chlorine gas to the environment. Again, using the EPA's RMP Guidance for Waste Water Treatment Plant Reference Tables or Equations it was determined that in this area with an Atmospheric Stability Class of D, and a wind speed of 3.0 meters per second, the distance to endpoint is 0.08 miles. The estimated residential population within this area is 17. Again, the mitigating effects of the enclosure or the dike are not factored into this scenario. Our accidental release prevention program is a model one. We pride ourselves on the caution and skill with which we undertake all activities related to chlorine use and maintenance. In light of the amounts we deal with this is not only a necessity, but smart. We are pro-active about chlorine handling safety and maint ain a "one in, one out" protocol whereby one man is within the enclosure connecting and disconnecting chlorine cylinders while another waits outside (with SCBA equipment at the ready) to be of assistance in the unlikely event of an accidental release. We are currently in compliance with state-delegated OSHA requirements including the PSM portions as well as those of 29 CFR 1910.38. In addition, we have electronic chlorine leak detectors within the chlorine room (enclosure) and the chlorinator room (site of rotameters, chlorine analyzer, etc.) as well. The Clarksville Wastewater Treatment Plant has been extremely fortunate in that there have been no accidental chlorine releases in over 20 years. However, our emergency response programs are in place and ready should the need arise. There are several HAZMAT teams within the city to respond to such incidents. Some of these are comprised of teams organic to the fire department and others are based at the Montgomery County Emergency M anagement Association. Public notification of a hazardous release would be accomplished through the local television and radio media organizations. Persons in the hazard area could also be notified through neighborhood or house to house alerting. Recent training received by plant personnel has included on-site demonstration of Computer Aided Modeling of Emergency Operations (C.A.M.E.O.) and Area Locations and Hazardous Atmospheres (A.L.O.H.A.) software systems currently in use by local HAZMAT teams. Changes that are foreseen in the area of safety include increased training in scenario modeling to allow plant and emergency responders to become familiar with the most likely scenarios for accidental chlorine release based on the most frequent direction of prevailing winds at the plant. A much safer and more practical method of chlorine-related procedures monitoring is also in the planning stages. In this method, members of a nearby fire station would actually be standing by on-site during tank connecting/disconnecting procedures. Their expertise would no doubt greatly enhance operator safety and confidence during the previously mentioned and potentially hazardous procedures. In closing, we wish to plainly state that our facility, its managers, and employees are making, and will continue to make every effort to ensure the continued safety of all those who live, work, or play around our facility. 1.0 SOURCE The Gillette Company (Gillette) in St. Paul, Minnesota is subject to the USEPAs Risk Management Program (RMP) for Accidental Chemical Release regulations (40 CFR 68) because the facility has quantities of propane, isobutane and butane mixtures greater than the threshold quantity (10,000 pounds) (CAS Numbers 74-98-6, 75-28-5 and 106-97-8). The propane, isobutane and n-butane mixtures are used as propellants for cans of hair products. There are two storage tanks within a tank farm that contain the regulated flammables. One tank is 40,000 gallons in size and another is 12,000 gallons in size. 2.0 POTENTIAL RELEASE SCENARIOS As required by the RMP rule requirements, two specifically defined release scenarios (a worst-case and an alternative-case release) were analyzed. The release scenarios were analyzed based upon the guidance contained in the USEPAs Risk Management Program Guidance for Propane Storage Facilities (the Propane Guidance), dated October 1998, and USEPAs Offsite Consequence Analysis Guidance (OCAG), dated May 1996. 2.1 WORST-CASE RELEASE For the worst-case release, the facility must assume that the entire contents of the largest vessel are released, a vapor cloud forms, and a detonation occurs. The distance to the endpoint (EP) is defined as the distance an explosion from an accidental release will travel before dissipating to the point that serious injuries from short-term exposures will no longer occur. For flammable gases, the EP is an overpressure of 1 psi (at 1 psi, windows will break). The calculated distance to the endpoint for a worst case release of approximately 184,900 pounds of the propane, n-butane mixture is 0.46 miles. Within this worst-case release, there are apartments and houses with a total population of 1981, recreation areas and commercial/industrial areas. There are no environmental receptors within this worst-case release. Although the worst-case consequence analysis is required by the RMP, it should be considered a highly unlikely event. Design, construction, and operation of the storage tanks is such that catastrophic failure is extremely remote. The storage tank was designed and constructed in accordance with the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Section VIII), and was certified and stamped in compliance with the National Board of Pressure Vessel Inspectors (National Board). The worst-case release scenario is unlikely for the following additional reasons: ? The facility has a preventive maintenance program in pla ce to maintain the ongoing integrity of the vessels; ? The facility has a training program designed to ensure that the system is operated by qualified personnel; ? The area is fenced and locked to prevent tampering. 2.2 ALTERNATIVE-CASE RELEASE The alternative scenario is considered to be a release of flammable gases that is more likely to occur than the worst-case scenario, and reaches an endpoint offsite. One of the release scenarios outlined in the Propane Guidance was chosen for analysis, which involves a tank truck driver who fails to remove the hoses between the storage tank and the transfer vehicle before moving the vehicle. In this case, the analysis considers the failure of a 25 foot length of unloading hose, 4 in diameter. The active mitigation devices are assumed to work as designed, limiting the release to the contents of the hose. The distance from the explosion where overpressure exceeds 1 psi is 175 feet. No public or environmental receptors would be affected by this alternative-case release. The alternative release scenario is unlikely for the following reasons: ? The facility has a preventive maintenance program in place to maintain the ongoing integrity of the system; and ? The facility has a training program designed to ensure that the system is operated by qualified personnel, especially during transfer operations. 3.0 PREVENTION PROGRAM The facility has carefully considered the potential for accidental releases of the flammable gases. To minimize the probability and severity of these mixtures releasing, a prevention program that satisfies the Occupational Safety and Health Administration (OSHA), Process Safety Management (PSM) of Highly Hazardous Chemicals (29 CFR 1910.119) has been implemented. The key components of the prevention program are summarized below: ? The development and documentation of critical process safety information regarding the hazards of flammable gases, the design basis of the system, and the equipment . ? The performance of a formal process hazard analysis (PHA) on the propellant system using a "What-If" Analysis. A team with expertise in engineering, operations, maintenance, and safety evaluated the existing propellant system in depth and developed recommendations to improve the safety and operability of the system. ? Standard operating procedures (SOPs) are used to provide the basis for proper and safe operation of the critical system components. ? System operators are fully trained in safe operating procedures before they work in each area. The training content is based on the process safety information and operating procedures. The training program ensures that the operators understand the nature and causes of problems arising from system operations and serves to increase awareness with respect to the hazards particular to the flammables in the process. ? Contractors that are hired to work on, or adjacent to, the covered processes are pre-qualified based on their knowledge of the chemicals, understanding of applicable codes and standards, and their demonstrated ability to work safely. In addition, these contractors are periodically evaluated to ensure that they continue to work safely. ? A computerized preventative maintenance program is utilized at the facility. This includes regular inspection and calibration of liquid level sensors, temperature and pressure instruments, switches and shutdown devices that have safety implications. ? Formal authorization systems (i.e., management of change procedures, pre-startup safety reviews) are utilized to ensure that system changes or expansions are as safe as the original design and that an independent recheck confirms that the changes are consistent with the engineering design and in a condition to be safely operated prior to startup. ? Events that might cause an accidental or unexpected release of the flammables are subjected to a formal investigation. The objective of the investigation is to correct deficie ncies in such a way as to prevent recurrence. ? Prior to the performance of any hot work (i.e., spark or flame producing operations such as welding, cutting, brazing, grinding), management must approve the work by executing a written hot work authorization permit to verify that precautions to prevent fire have been implemented. ? Planning with the local fire department is conducted to ensure a rapid response to potential incidents with the system or external events, such as floods or tornadoes. ? Prevention program compliance audits are performed every three years to verify that the appropriate management systems are in place and are being properly implemented. Any deficiencies found in an audit is addressed. 4.0 ACCIDENT HISTORY There have been no accidental releases of the flammable gases at the Gillette facility in the last five years that have resulted in death, injury, or significant property damage on site or off-site death, injury, evacuation, sheltering in place, property dama ge, or environmental damage. 5.0 EMERGENCY RESPONSE PROGRAM The Gillette facility has implemented a detailed written Emergency Response Plan (ERP). The ERP is intended to address all emergencies at the facility, including incidents related to a release of flammable gases. |